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RC General Buying Decisions

veh1Radio controlled vehicles/craft can be fairly cleanly divided into two categories, toy and hobby-level. The toy type are what most people think of when you mention “RC” — buy-and-drive playthings that you can purchase from a toy or electronics store. These are made strictly for the sake of fun. Then there are the more sophisticated and capable models targeted towards hobbyists who want to go faster, tinker with settings and upgrades, and perhaps participate in one of the many levels of established competitive events. Neither class of RC is necessarily “better” — they each have their positive and negative qualities. However, when you’re first starting out, it’s very worthwhile to choose which way you want to go up front, long before you pull out your credit card. This article presents the most important facts that can help you make an informed decision.                                                                                                                                            

Cost

Toy R/C cars & trucks that you can buy at places like Toys R Us or Walmart start at $20-25 USD, and the most extreme ones top out around $150. Toy R/C planes start at around $30. When you step up to the hobby level, you’ll be hard pressed to find something complete for under $130. It’s very easy to spend $400-500 on a 1/10th scale car or truck that will last awhile, and a fully upgraded rig can easily shoot up to $2,000-3,000 USD.

Speed

In most cases, there’s really no comparison between the performance of toy and hobby-level RCs. Most toy cars & trucks will go anywhere from 5mph to 15mph, with the fastest few doing 20-24mph. Hobby-level RCs generally start at 15-25mph for electrics and 25-35mph for nitro versions. You can get monster trucks that will do over 40mph out of the box, and low-slung street cars that will do over 60 with no upgrades or modifications. In planes, the toys generally go around 5-15mph, while there are hobby-class craft that will do 30, 50, even 80mph in factory stock form. The most extreme speed differences are in boats. The toys often putt and crawl along at 1-5mph, while the hottest hobby-level racing boats will skim the surface at over 100mph

Durability

Mostly because they’re slow, toy RCs tend to handle more abuse than their more expensive cousins. The most common things to break are bumpers and body trim. The land and water-borne vehicles are built with a lot more material than is necessary, while aircraft tend to be constructed of foam and flexible plastics that bounce back after being bent. However…

When they break…

Repairing a toy RC is sometimes not worth the time & effort. Nearly all use multifunction circuit boards that combine several major functions, so if something goes electrically wrong, you have to change out the whole thing. Most manufacturers don’t have a factory service program, so you have to do the work yourself. Many don’t even offer a way to order new parts. Nikko is a notable exception. You can call them, tell them exactly what vehicle you have, describe the problem, and order precisely the part(s) you need. Many RC’s available at Radio Shack are actually from Nikko and are covered by this same level of support, with the additional convenience of being able to go back to the store and special-order your parts in person.

Fixing hobby-level RCs is, in most cases, a completely different affair. You can disassemble anything yourself. With most popular brands there are manuals and exploded views. There are service departments that handle returns of defective components. Electronics are, with rare exception, separated by function so that you don’t have to change your speed controller if your radio receiver crystal goes bad. Parts are available at brick-and-mortar hobby shops and dozens of trusted, popular web sites. There are online forums (message boards) where you can ask other hobbyists for advice and learn from their experience. veh2

Upgradability

These days, ever more toy RCs have upgrades available for purchase from the original manufacturer, particularly amongst the smaller “micro” cars and trucks. These upgrades can range from different body kits to stickier tires to faster motors. They’re generally very easy to install, requiring at most a small screwdriver (which is often included) and 15 minutes, and can dramatically change the look or performance of the vehicle. They’re also great fun to install and let the owner add a bit of their own personality.

The most popular hobby RCs may have literally hundreds of upgrades available from many different aftermarket sources (companies other than the original manufacturer). Among the available upgrades may be anything from scale-realistic wheels to anodized aluminum struts in various colors to larger motors/engines to total conversion kits that fundamentally change the vehicle. Many hobby-level RC parts are reusable from one vehicle to another, especially electronic components and motors/engines. Popular RC models come with the support of other owners nationwide or around the world who share their experiences, tips, and home-grown modifications freely on the Internet.

Controllability

Toy radio systems traditionally give you forward/reverse (or up/down) and left/right direction control. A growing number of cars & trucks these days now have “digital proportional” steering to boot, which gives you a number of steps between neutral and full turning, depending upon how far you turn the wheel or push the stick on the radio transmitter. Some, though, only let you go straight forward or to turn one pre-set direction in reverse. Toy helicopters are what you have to watch out for the most, as these sometimes give you only one axis of control — go straight up, or come straight down. Most toy RC’s are still only available on two frequencies (e.g., 27mhz and 49mhz in the US), with a few now offering 3 to 6 possibilities. This limits the number of vehicles that can run at one time, but more unfortunately it reduces the possibility of even being able to run two random vehicles together.

Hobby-class radio systems give you 64 to 256 (or more) steps of control in each direction for what feels like perfectly smooth turning & throttle control. These systems can also be easily changed between anywhere from 6 to 30 different frequencies, so even if the one person you want to race against or fly with has an absolutely identical radio setup, for around $20 and with a one-minute part swap, you’re both in the clear. Still better, the most recent generation of radio systems, while expensive, operate on an extremely high frequency and use small computer chips to automatically search for and lock onto an open channel, ensuring that you’ll never have a frequency conflict.

Raceability

Toy RCs can be raced between siblings or friends around the neighborhood, but there’s generally no sanctioned racing. Hobby-level RCs are raced around the world in local, regional, national, and even international events, even including multi-track tours.

Ownership

When all is said and done, the purchase decision between toy & hobby-level RCs should always come down to who the purchase is being made for. You don’t want to buy a $390, 45mph nitro-powered car for a 6-year-old. Likewise, a 16-year-old who wants to get into RC racing for sport wouldn’t be well-served by a $39 toy. What’s really interesting is the 26-year-old with a $25 micro-sized monster truck who would derive hours of fun from chasing his/her cat around the kitchen floor or gingerly driving around a makeshift desktop obstacle course during lunchtime at work. Before you buy an RC, know who you’re buying it for and do a little research. That extra time spent up front could make the difference between tremendous fun and awkward disappointment. Credits: http://www.beginningrc.com/ http://

Aerodynamics

  • IntroductionAerodynamics is the study of forces and motion of objects through the air.

     

    Basic knowledge of theaero1
    aerodynamic principles
    is highly recommended
    before getting involved
    in building and/or flying
    model aircraft.
    • A model aircraft that is hanging still in air during strong winds may be subject
      to the same aerodynamic forces as a model aircraft that is flying fast during
      calm weather.
      The aerodynamic forces depend much on the air density.

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  • For example, if a glider glides 25 meters
    from a given altitude during low air density
    it may glide 40 meters during high density.


    The air density depends on the atmospheric pressure and on the air temperature.
    The air density increases with decreasing of the air temperature and/or with
    increasing of the atmospheric pressure.
    The air density decreases with increasing of the air temperature and/or with
    decreasing of the atmospheric pressure.
    A flying aircraft is subject to a pressure depending on the airspeed and the
    air density.
    This pressure increases exponentially with increasing of the airspeed.
    The aircraft’s resistance to the airflow (drag) depends on the shape of the
    fuselage and flying surfaces.
    An aircraft that is intended to fly fast has a thinner and different wing profile
    than one that is intended to fly slower.
    That’s why many aircraft change their wings’ profiles on landing approach
    by lowering the flaps located at the wings’ trailing edge and the slats at the
    leading edge in order to keep enough lifting force during the much lower
    landing speed.

    The wings’ profile of an aircraft is usually asymmetric, which makes the
    pressure on the wings’ upper side lower than the underside, causing the air on
    the wings upper side to accelerate downwards, thereby a lift force is created.

    The air always flows away from areas of higher pressure toward areas of lower
    pressure, thus the air over the wing top accelerates as it enters the lower
    pressure region (where the air curves toward the wing), whereas the air under
    the wing slows down as it enters the higher pressure region.
    So, one may also say that the wings create lift by reacting against the air flow,
    driving it downwards, producing downwash.
    The top of the wing is often the major lift contributor, usually producing twice as
    much lift as the bottom of the wing.

    The lift force of a symmetric profile is based on the airspeed and on a positive
    angle of attack to the airflow, which makes the air react as it was asymmetric.

    The following picture shows the airflow through two wing profiles.

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  • The uppermost profile has a lower angle of attack than the lowest one.
    When the air flows evenly through the surface is called a laminar flow.
    A too high angle of attack causes turbulence on the upper surface, which
    dramatically increases the air resistance (drag), this may cause the flow
    to separate from the upper surface resulting in an abrut reduction in lift,
    known as stall.Summarising:
    The aircraft generates lift by moving through the air.
    The wings have airfoil shaped profiles that create a pressure difference
    between upper and lower wing surfaces, with a high pressure region
    underneath and a low pressure region on top.
    The lift produced will be proportional to the size of the wings, the square
    of airspeed, the density of the surrounding air and the wing’s angle of
    attack to on-coming flow before reaching the stall angle.

    How does a glider generate the velocity needed for flight?
    The simple answer is that a glider trades altitude for velocity.
    It trades the potential energy difference from a higher altitude to a lower
    altitude to produce kinetic energy, which means velocity.
    Gliders are always descending relative to the air in which they are flying.

    How do gliders stay aloft for hours if they constantly descend?
    The gliders are designed to descend very slowly.
    If the pilot can locate a pocket of air that is rising faster than the
    glider is descending, the glider can actually gain altitude, increasing
    its potential energy.

    Pockets of rising air are called updrafts.
    Updrafts are found when the wind blowing at a hill or mountain rises to
    climb over it. (However, there may be a downdraft on the other side!)
    Updrafts can also be found over dark land masses that absorb more
    heat from the sun than light land masses.
    The heat from the ground heats the surrounding air, which causes the
    air to rise. The rising pockets of hot air are called thermals.

    Large gliding birds, such as owls and hawks, are often seen circling
    inside a thermal to gain altitude without flapping their wings.
    Gliders can do exactly the same thing.

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  • Wing Geometry Definitions
    A vertical cut through the wing parallel to flight’s direction (plan view) will show
    the cross-section of the wing.
    This side view (profile) is called Airfoil, and it has some geometry definitions
    of its own as shown on the picture below.

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      The longest straight line that can be drawn from the Airfoil’s leading edge to
      trailing edge is called the

Chord Line

      .
      The Chord Line cuts the airfoil into an upper surface and a lower surface.
      If we plot the points that lie halfway between the upper and lower surfaces,
      we obtain a curve called the

Mean Camber Line

      .
      For a symmetric airfoil (upper surface the same shape as the lower surface)
      the Mean Camber Line will fall on top of the Chord Line.
      But for an asymmetric airfoil, these are two separate lines. The maximum
      distance between these two lines is called the

Camber

      , which is a measure
      of the curvature of the airfoil (high camber means high curvature).
      Asymmetric airfoils are also known as cambered airfoils.
      The maximum distance between the upper and lower surfaces is called the

Thickness

      .
    Both Thickness and Camber are expressed as a percentage of Chord.

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      Airfoils can come with all kinds of combinations of camber and thickness
      distributions. They are designed for the condictions under which the plane is
      likely to be flown most of the time.
      NACA (the precursor of NASA) established a method of designating classes
      of airfoils and then wind tunnel tested the airfoils in order to provide
      lift coefficients and drag coefficients for designers.

Aspect Ratio

      is a measure of how long and slender a wing is from tip to tip.
      The Aspect Ratio of a wing is defined to be the square of the span divided
      by the wing area and is given the symbol

AR

      .
      The formula is simplified for a rectangular wing, as being the ratio of the span
    to the chord length as shown on the figure below.

aero7

      Wing

Dihedral

      refers to the angle of wing panels as seen in the aircraft’s
      front view.
      Dihedral is added to the wings for roll stability; a wing with some Dihedral
      will naturally return to its original position if it is subject to a briefly slight
      roll displacement.
      Most large airliner wings are designed with Dihedral.
      On the contrary the highly maneuverable fighter planes have no Dihedral.
      In fact, some fighter aircraft have the wing tips lower than the roots, giving
      the aircraft a high roll rate.
    A negative Dihedral angle is called Anhedral.

  • Forces in FlightGravity, Lift, Thrust and Drag.

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  • Gravity is a force that is always directed toward the centre of the earth.
    The magnitude of the force depends on the mass of all the aircraft parts.
    The gravity is also called weight and is distributed throughout the aircraft.
    But we can think of it as collected and acting through a single point called
    the centre of gravity.
    In flight, the aircraft rotates about its centre of gravity, but the direction of the
    weight force always remains toward the centre of the earth.Lift is the force generated in order to overcome the weight, which makes the
    aircraft fly.
    This force is obtained by the motion of the aircraft through the air.

    Factors that affect lift:

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  • Lift force is therefore dependent on the density of the air r, the airspeed V,
    the type of airfoil and on the wing’s area according to the formula below:Lift Force = 0.5 * r * V2 * Wing’s Lift Coefficient * Wing Area

    Where the Lift Force is in Newton, Wing Area in m2 and the airspeed in m/s.
    The standard density of the air is 1.225kg/m3.

    The wing’s lift coefficient is a dimensionless number that depends on the airfoil
    type, the wings aspect ratio (AR), Reynolds Number and is proportional to the
    angle of attack (AoA) before reaching the stall angle.

    Thrust is the force generated by some kind of propulsion system.
    The magnitude of the thrust depends on many factors associated with the
    propulsion system used:

    – type of engine
    – number of engines
    – throttle setting
    – speed

    The direction of the force depends on how the engines are attached to
    the aircraft.

    The glider, however, has no engine to generate thrust. It uses the potential
    energy difference from a higher altitude to a lower altitude to produce kinetic
    energy, which means velocity.
    Gliders are always descending relative to the air in which they are flying.

    Drag is the aerodynamic force that opposes an aircraft’s motion through the air.

    Drag is generated by every part of the aircraft (even the engines).

    There are several sources of drag:

    One of them is the skin friction between the molecules of the air and the
    surface of the aircraft.
    The skin friction causes the air near the wing’s surface to slow down.
    This slowed down layer of air is called the boundary layer.
    The boundary layer builds up thicker when moving from the front of the airfoil
    toward the wing trailing edge.
    Another factor is called the Reynolds effect, which means that the slower we
    fly, the thicker the boundary layer becomes.

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  • Form drag is another source of drag.
    This one depends on the shape of the aircraft.
    As the air flows around the surfaces, the local airspeed and pressure changes.
    The component of the aerodynamic force on the wing that is opposed
    to the motion is the wing’s drag, while the component perpendicular to the
    motion is the wing’s lift.Induced drag is a sort of drag caused by the wing’s generation of lift.
    One cause of this drag is the flow near the wing tips being distorted as a result
    of the pressure difference between the top and the bottom of the wing, which in
    turn results in swirling vortices being formed at the wing tips.
    The induced drag is an indication of the amount of energy lost to the tip vortices.
    The swirling vortices cause downwash near the wing tips, which reduces the
    overall lift coefficient of the wing.

aero11

  • The picture below shows the downwash caused by an aircraft.

aero12

  • The Cessna Citation has just flown through a cloud.
    The downwash from the wing has pushed a trough into the cloud deck.
    The swirling flow from the tip vortices is also evident.The wing geometry (aspect ratio AR) also affects the amount of induced drag:
    Long wing with a small chord (high AR) has low induced drag, whereas a short
    wing with a large chord (low AR) has high-induced drag.
    For the same chord, the wing with a high AR has higher lift coefficient, but stalls
    at lower angle of attack (AoA) than the wing with a low AR.
    Also, aircraft with high AR wings are more sensitive to elevator control.

    The induced drag increases with increasing of the wing’s actual lift coefficient
    being generated and it’s proportional to the square of the angle of attack.
    And since a slower airspeed requires a higher angle of attack (AoA) to produce
    the same lift, the slower the airspeed is, the greater the induced drag will be.
    So, the induced drag is also inversely proportional to the square of the airspeed.

    In order to minimise tip vortices some designers design a special shape for
    the wing tips.
    With drooped or raised wing tips, the vortex is forced further out.

aero13 

  • However, this method will cause an increase in weight since they need to be
    added to the wing tip.An easier and lighter method is by cutting the wing tip at 45-degrees.
    With a small radius at the bottom and a relatively sharp top corner, the air from
    the secondary flow travels around the rounded bottom but can’t go around the
    sharp top corner and is pushed outward.

aero14

  • There’s also the Interference drag, which is generated by the mixing of
    streamlines between one or more components, it accounts for 5 to 10%
    of the drag on an airplane.
    It can be reduced by proper fairing and filleting which allows the streamlines
    to meet gradually rather than abruptly.All drag that is not associated with the production of lift is defined as
    Parasitic drag.

    The graph below shows the induced and the parasitic drag versus airspeed.
    Total drag is the induced drag plus the parasitic drag.

aero15

  • Since during constant speed and level flight the thrust is equal to the total drag
    the graph also shows how much thrust is needed at different level flight speeds.At take-off (just above the stall speed), a high AoA is needed to get enough lift
    which increases the total drag and also the thrust needed.
    As the speed increases, the AoA needed to get the same lift decreases and so
    does the total drag until the minimum drag speed is reached, above which the
    total drag starts increasing exponentially (and so does the thrust needed).
    The plane’s max level speed will be limited by the prop’s pitch speed or by the
    max thrust available, which altogether means by the max power available.

 

  • Stability ConceptsThe aircraft’s response to momentary disturbance is associated with its
    inherent degree of stability built in by the designer, in each of the three axes,
    and occurring without any reaction from the pilot.

    There is another condition affecting flight, which is the aircraft’s state of trim
    or equilibrium (where the net sum of all forces equals zero).
    Some aircraft can be trimmed by the pilot to fly ‘hands off’ for straight and
    level flight, for climb or for descent.

    Free flight models generally have to rely on the state of trim built in by the
    designer and adjusted by the rigger, while the remote controlled models have
    some form of trim devices which are adjustable during the flight.

    An aircraft’s stability is expressed in relation to each axis:
    lateral stability (stability in roll), directional stability (stability in yaw)
    and longitudinal stability (stability in pitch).
    Lateral and directional stabilities are inter-dependent.

aero16

  • Stability may be defined as follows:
    – Positive stability: tends to return to original condition after a disturbance.
    – Negative stability: tends to increase the disturbance.
    – Neutral stability: remains at the new condition.
    Static stability: refers to the aircraft’s initial response to a disturbance.
    A statically unstable aircraft will uniformly depart from a condition of equilibrium.

    Dynamic stability: refers to the aircraft’s ability to damp out oscillations, which
    depends on how fast or how slow it responds to a disturbance.
    A dynamically unstable aircraft will (after a disturbance) start oscillating with
    increasing amplitude.
    A dynamically neutrally stable aircraft will continue oscillating after a disturbance
    but the amplitude of the oscillations will not change.

    So, a statically stable aircraft may be dynamically unstable.
    Dynamic instability may be prevented by an even distribution of weight inside the
    fuselage, avoiding too much weight concentration at the extremities or at the CG.
    Also, control surfaces’ max throws may affect the flight stability, since a too much
    control throw may cause instability, e.g. Pilot Induced Oscillations (PIO).

    Static stability is proportional to the stabiliser area and the tail moment.
    You get double static stability if you double the tail area or double the tail moment.
    Dynamic stability is also proportional to the stabiliser area but increases with the
    square of the tail moment, which means that you get four times the dynamic stability
    if you double the tail arm length.

    However, making the tail arm longer or encreasing the stabiliser area will move
    the mass of the aircraft towards the rear, which may also mean the need to make
    the nose longer in order to minimize the weight required to balance the aircraft…

    A totally stable aircraft will return, more or less immediately, to its trimmed state
    without pilot intervention.
    However, such an aircraft is rare and not much desirable. We usually want an
    aircraft just to be reasonably stable so it is easy to fly.
    If it is too stable, it tends to be sluggish in manoeuvring, exhibiting too slow
    response on the controls.

    Too much instability is also an undesirable characteristic, except where an
    extremely manoeuvrable aircraft is needed and the instability can be continually
    corrected by on-board ‘fly-by-wire’ computers rather than the pilot, such as a
    supersonic air superiority fighter.

    Lateral stability is achieved through dihedral, sweepback, keel effect and
    proper distribution of weight.
    The dihedral angle is the angle that each wing makes with the horizontal (see
    Wing Geometry).
    If a disturbance causes one wing to drop, the lower wing will receive more lift
    and the aircraft will roll back into the horizontal level.

    A sweptback wing is one in which the leading edge slopes backward.
    When a disturbance causes an aircraft with sweepback to slip or drop a wing,
    the low wing presents its leading edge at an angle more perpendicular to the
    relative airflow. As a result, the low wing acquires more lift and rises, restoring
    the aircraft to its original flight attitude.

    The keel effect occurs with high wing aircraft. These are laterally stable simply
    because the wings are attached in a high position on the fuselage, making the
    fuselage behave like a keel.
    When the aircraft is disturbed and one wing dips, the fuselage weight acts like
    a pendulum returning the aircraft to the horizontal level.

    The tail fin determines the directional stability.
    If a gust of wind strikes the aircraft from the right it will be in a slip and the fin
    will get an angle of attack causing the aircraft to yaw until the slip is eliminated.

aero17aero18

  • Longitudinal stability depends on the location of the centre of gravity, the
    stabiliser area and how far the stabiliser is placed from the main wing.
    Most aircraft would be completely unstable without the horizontal stabiliser.
    Non-symmetrical cambered airfoils have a higher lift coefficient, but they also
    have a negative pitching moment (Cm) tending to pitch nose-down, and thus
    being statically unstable, which requires the counter moment produced by the
    horizontal stabiliser to get adequate longitudinal stability.
    The stabiliser provides the same function in longitudinal stability as the fin does
    in directional stability.

    Symmetrical (zero camber) airfoils have normally a zero pitching moment,
    resulting in neutral stability, which means the aircraft goes wherever you point it.
    Reflexed airfoils (with trailing edge bent up) have a positive pitching moment
    making them naturally stable, they are often used with flying wings (without the
    horizontal stabiliser).

    It is of crucial importance that the aircraft’s Centre of Gravity (CG) is located
    at the right point, so that a stable and controllable flight can be achieved.
    In order to achieve a good longitudinal stability, the CG should be ahead of the
    Neutral Point (NP), which is the Aerodynamic Centre of the whole aircraft.
    NP is the position through which all the net lift increments act for a change in
    angle of attack.
    The major contributors are the main wing, stabiliser surfaces and fuselage.

    The bigger the stabiliser area in relationship to the wing area and the longer
    the tail moment arm relative to the wing chord, the farther aft the NP will be and
    the farther aft the CG may be, provided it’s kept ahead of the NP for stability.

aero19

  • The angle of the fuselage to the direction of flight affects its drag, but has little
    effect on the pitch trim unless both the projected area of the fuselage and its
    angle to the direction of flight are quite large.
    A tail-heavy aircraft will be more unstable and susceptible to stall at low speed
    e. g. during the landing approach.
    A nose-heavy aircraft will be more difficult to takeoff from the ground and to
    gain altitude and will tend to drop its nose when the throttle is reduced. It also
    requires higher speed in order to land safely.

    The angle between the wing chord line and the stabiliser chord line is called
    the Longitudinal Dihedral (LD) or decalage.
    For a given centre of gravity, there is a LD angle that results in a certain
    trimmed flight speed and pitch attitude.
    If the LD angle is increased the plane will take on a more nose up pitch attitude,
    whereas with a decreased LD angle the plane will take on a more nose down
    pitch attitude.
    There is also the Angle of Incidence, which is the angle of a flying surface
    related to a common reference line drawn by the designer along the fuselage.
    The designer might want this reference line to be level when the plane is flying
    at level flight or when the fuselage is in it’s lowest drag position.
    The purpose of the reference line is to make it easier to set up the relationships
    among the thrust, the wing and the stabiliser incidence angles.
    Thus, the Longitudinal Dihedral and the Angle of Incidence are interdependent.

    Longitudinal stability is also improved if the stabiliser is situated so that it lies
    outside the influence of the main wing downwash.
    Stabilisers are therefore often staggered and mounted at a different height in
    order to improve their stabilising effectiveness.

    It has been found both experimentally and theoretically that, if the aerodynamic
    force is applied at a location 1/4 from the leading edge of a rectangular wing
    at subsonic speed, the magnitude of the aerodynamic moment remains nearly
    constant even when the angle of attack changes.
    This location is called the wing’s Aerodynamic Centre AC.
    (At supersonic speed, the aerodynamic centre is near 1/2 of the chord).

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  • In order to obtain a good Longitudinal Stability the Centre of Gravity CG
    should be close to the main wings’ Aerodynamic Centre AC.
    For wings with other than rectangular form (such as triangular, trapezoidal,
    compound, etc.) we have to find the Mean Aerodynamic Chord – MAC,
    which is the average for the whole wing.
    The MAC calculation requires rather complicated mathematics, so a simpler
    method called ‘Geometric Mean Chord’ GMC or ‘Standard Mean Chord’ SMC
    may be used as shown on the drawings below.
    MAC is only slightly bigger than GMC except for sharply tapered wings.
    Taper ratio = tip chord/root chord.

aero21

  • To calculate MAC of a tapered wing, the following simplified equation
    may be used:
    MAC = root chord * 2/3 * ((1+T+T2)/(1+T))
    Where T is the wing’s taper ratio.
    The MAC distance from the center line may be calculated as follows:
    distance = half span * (1+2*T)/(3+3*T)

aero22

  • For a delta wing the CG should be located 10% ahead of the geometrically
    calculated AC point as shown above.

aero23

  • The MAC of an elliptical wing is 85% of the root chord and is located at 42.4% of
    the half wingspan from the root chord.
    Elliptical wing’s area = pi * wingspan * root chord/4
    The AC location for biplanes with positive stagger (top wing ahead of the bottom
    wing), is found according to the drawing below.

aero24

  • For conventional designs (with main wing and horizontal stab) the CG location
    range is usually between 28% and 33% from the leading edge of the main
    wing’s MAC, which means between about 5% and 15% ahead of the aircraft’s
    Neutral Point NP.
    This is called the Static Margin, which is expressed as a percentage of MAC.
    When the static margin is zero (CG coincident with NP) the aircraft is considered
    “neutrally stable”.
    However, for conventional designs the static margin should be between 5% and
    15% of the MAC ahead of the NP.
    The CG location as described above is pretty close to the wing’s Aerodynamic
    Center AC because the lift due to the horizontal stab has only a slightly effect on
    the conventional R/C models.

    However, those figures may vary with other designs, as the NP location depends
    on the size of the main wing vs. the stab size and the distance between the main
    wing’s AC and the stab’s AC.
    The simplest way of locating the aircraft’s NP is by using the areas of the two
    horizontal lifting surfaces (main wing and stab) and locate the NP proportionately
    along the distance between the main wing’s AC point and the stab’s AC point.
    For example, the NP distance to the main wing’s AC point would be:
    D = L · (stab area) / (main wing area + stab area) as shown on the picture below:

aero25

  • There are other factors, however, that make the simple formula above inaccurate.
    In case the two wings have different aspect ratios (different dCL/d-alpha) the NP
    will be closer to the one that has higher aspect ratio.
    Also, since the stab operates in disturbed air, the NP will be more forward than
    the simple formula predicts.
    The figure below shows a somewhat more complex formula to locate the NP but
    would give a more accurate result using the so called Tail Volume Ratio, Vbar.
    This formula gives the NP position as a percentage (%) of the wing’s MAC aft of
    the wing’s AC point.

aero26

  • For those who are not so keen on formulas and calculations there is the
    Aircraft Center of Gravity Calculator, which automatically calculates the CG
    location as well as other usuful parameters based on the formula above.
    For Canards check the link below:
    Canard Center of Gravity Calculator

    For further equations on how to find the proper CG location with different wing
    shapes and design configurations including Canards, check here.

  • Stall and SpinOne of the first questions a pilot might ask, when converting to a new aircraft
    type, is “What’s the stall speed?”
    The reason for the enquiry is that usually, but not always, the approach speed
    chosen for landing is 1.3 times the stall speed.
    Stall is an undesirable phenomenon in which the aircraft wings produce an
    increased air resistance and decreased lift, which may cause an aircraft
    to crash.

    The stall occurs when the airflow separates from the upper wing surface.
    It happens when a plane is under too great an Angle of Attack (AoA).
    For light aircraft, without high-lift devices, the critical angle is usually around 16°.
    The picture below shows a stalled airfoil:

aero27

  • Geometric Angle of Attack is the angle between the airfoil chord line and the
    direction of flight. The Angle of Attack is also known as Alpha.
    The angle of attack measured relative to zero coefficient of lift is called the
    Absolute Angle of Attack (Absolute AoA).
    There’s also the Pitch Angle, which is measured with respect to the horizon.
    For symmetric airfoils the Absolute AoA is equal to the Geometric AoA,
    whereas for asymmetric (cambered) airfoils these two angles are different, since
    these airfoils still produce lift at zero Geometric Angle of Attack as shown below.

aero28

  • For airfoils of one family the symmetric airfoil stalls at a higher Geometric AoA
    compared with the cambered airfoil, however the cambered airfoil has higher
    lift coefficient and stalls at a higher Absolute AoA.
    As mentioned in the chapter Forces in Flight, the lift force is proportional to the
    density of the air r, the square of the airspeed V, the type of airfoil and to the
    wing’s area according to the formula:

    Lift force = 0.5 * r * V2 * wing’s lift coefficient * wing area

    Since lift coefficient is proportional to the angle of attack, the lower the airspeed
    the higher the angle of attack has to be in order to produce the same lift.

    Thus, stall may occur during take-off or landing, just when the airspeed is low:
    To keep altitude at low airspeed, the wing’s lift coefficient has to increase, and if
    a non-experienced pilot tries to lift the aircraft’s nose at a too low airspeed, it may
    exceed the critical angle of attack and stall occurs.
    If you’re flying near the stall speed and make a steep turn, the aircraft will stall.
    That’s because, if the aircraft stalls for instance at 20 knots in straight level flight,
    it will stall at 28.2 knots in a 60 degree banked turn.
    The rapid reduction in speed after passing the critical angle of attack means
    the wing is now unable to provide sufficient lift to totally balance weight and,
    in a normal stall, the aircraft starts to sink, but if one wing stalls before the
    other, that wing will drop, the plane falls out of the air. The ground waits below.

    Stalls may also occur at high airspeeds. If at max airspeed and full throttle the
    pilot suddenly applies excessive up elevator, the aircraft will rotate upwards,
    however, due to aircraft’s inertia, it may continue flying in the same direction
    but with the wings at an angle of attack that may exceed the stall angle.
    See an example here

    Stalling at high-speed gives a more dramatic effect than at low speed.
    This because the strong propeller wash causes one of the wings to stall first
    that combined with the high speed produces a snaproll followed by a spiral dive.
    This happens very fast causing the aircraft to dive at full throttle and unless
    there’s enough height for recovery, the crash will be inevitable.

    An aircraft with relatively low wing loading has a lower stall speed.
    (wing loading is the aircraft’s weight divided by the wing area)
    Since the airfoil also affects the stall speed and the max angle of attack, many
    aircraft are equipped with flaps (on the wing trailing edge), and some designs
    use slats (on the wing leading edge).
    Flaps increase the wing’s lift coefficient, but the simple ones may reduce the stall
    angle. Slats, on the other hand, increase the stall angle.

    Aircraft that are designed for Short Take-Off and Landing (STOL) use slots
    on the wing’s leading edge together with flaps on the trailing edge, which gives
    high lift coefficient and remarkable slow flying capabilities by allowing greater
    angle of attack without stalling.

aero29

  •  Cruise                     Climb
    

    The leading edge slots may prevent the stall up to approximately 30 deg. angle
    of attack by picking up a lot of air from below, accelerating the air in the funnel
    shaped slot (venturi effect) and forcing the air around the leading edge onto the
    upper wing surface.

    The disadvantage of the slots and flaps is that they produce higher drag.
    Since the high lift coefficient is only needed when flying slowly (take-off, initial
    climb, final approach and landing) some designs use retractable devices,
    which closes at higher speeds to reduce drag.

aero30

  • Such devices are seldom used in model aircraft (especially the smaller ones),
    mainly due to its complexity and also the increasing of wing loading, which
    may counter-act the increased lift obtained.
    The wing’s aspect ratio (AR) also affects the overall lif coefficient of the wing.
    For a given Re, the wing with higher AR (with long wingspan and small chord)
    reaches higher lift coefficient, but stalls at a lower angle of attack than the wing
    with low AR as shown below:

aero31

  • However, for a given wing area, increasing the aspect ratio may result in a too
    small wing chord with a too low Re number, which may significantly reduce the lift
    coefficient. This is likely to occur with small indoor planes.
    Another method to improve an aircraft’s stall characteristics is by using wing
    washout, which refers to wings designed so that the outboard sections
    have a lower angle of attack than the inboard sections in all flight conditions.

aero32

  • The outboard sections (toward the wing tips) will reach the stalling angle
    after the inboard sections, thus allowing effective aileron control as the stall
    progresses. This is usually achieved by building a twist into the wing structure
    or by using a different airfoil in the outboard section.
    A similar effect is achieved by the use of flaps.
    The aileron drag is a further factor that may cause an aircraft to stall.
    When the pilot applies aileron to roll upright during low speed, the downward
    movement of the aileron on the lower wing might take an angle on that part of
    the wing past the critical stall angle. Thus that section of wing, rather than
    increasing lift and making the wing rise, will stall, lose lift and the aircraft
    instead of straightening up, will roll into a steeper bank and descend quickly.

    Also the wing with the down aileron often produces a larger drag, which may
    create a yaw motion in the opposite direction of the roll.
    This yaw motion partially counteracts the desired roll motion and is called
    the adverse yaw.

    Following configurations are often used to reduce aileron drag:
    – Differential ailerons where the down-going aileron moves through a smaller
    angle than the up-going.
    – Frise ailerons, where the leading edge of the up-going aileron protrudes
    below the wing’s under surface, increasing the drag on the down-going wing.
    – And the wing washout.

    Stall due to aileron drag is more likely to occur with flat bottom wings.
    Since differential ailerons will have the opposite effect when flying inverted,
    some aircraft with symmetrical airfoils designed for aerobatics don’t use
    this system.
    The picture below illustrates an example of a Frise aileron combined with
    differential up/down movement.

aero33

  • Another factor that affects the aircraft’s stall characteristics is the location of
    its centre of gravity CG.
    A tail-heavy aircraft is likely to be more unstable and susceptible to stall at low
    speed, e. g. during the landing approach.
    Downwind stall:
    For instance, a powered plane flying north with airspeed of 30 knots against a
    30 knots headwind has zero ground speed.
    If you turn 90 deg. left (west), the plane’s airspeed still is 30 knots but is now
    drifting 30 knots to the south resulting in 42 knots ground speed to the southwest.
    If the plane keeps turning south, the drift due to the wind is still 30 knots but now
    the ground speed becomes 30+30 = 60 knots, while the airspeed still is 30 knots.

    The pilot on the ground will see the ground speed but not the airspeed, and since
    the plane seems to move much faster flying downwind, the pilot may instinctively
    slow down the plane below the stall speed.
    This results in a pilot-induced stall due to the optical illusion of the plane’s higher
    ground speed when flying downwind.

    Recovering from a stall:

    In order to recover from a stall, the pilot has to reduce the angle of attack
    back to a low value. Despite the aircraft is already falling toward the ground,
    the pilot has to push the stick forward to get the nose even further down.
    This reduces the angle of attack and the drag, which increases the speed.

    After the aircraft gained speed and the airflow incidence on the wing becomes
    favourable, the pilot may pull back on his stick to increase the angle of attack
    again (within allowable range) restoring the lift.
    Since recovering from a stall involves some loss of height, the stall is most
    dangerous at low altitudes.

    Engine power can help reduce the loss of height, by increasing the velocity
    more quickly and also by helping to reattach the flow over the wing.
    How difficult it is to recover from a stall depends on the plane. Some full-size
    aircraft that are difficult to recover have stick shakers: the shaking stick alerts
    the pilot that a stall is imminent.

    Spin

    A worse version of a stall is called spin, in which the plane spirals down.
    A stall can develop into a spin through the exertion of a sidewise moment.
    Depending on the plane, (and where its CG is located) it may be more difficult
    or impossible to recover from a spin.
    Recovery requires good efficiency from the tail surfaces of the plane; typically
    recovery involves the use of the rudder to stop the spinning motion, in addition
    to the elevator to break the stall. However the wings might block the airflow to
    the tail.
    If the centre of gravity of the plane is too far back, it tends to make recovery
    much more difficult.

    Another circumstance that may cause loss of control is when a hinged control
    surface starts to flutter.
    Such flutter is harmless if it just vibrates slightly at certain airspeed (possibly
    giving a kind of buzzing sound), but ceases as soon as the airspeed drops.
    In some cases however, the flutter increases rapidly so that the model is no
    longer controllable.
    The pilot may not be aware of the cause and suspect radio interference instead.
    To reduce the flutter, the control linkages should not be loosely fitted and the
    push rods should be stiff.
    Long unbraced push rods can create flutter as vibration whips them around.
    In some difficult cases the control surface has to be balanced, so that its centre
    of mass (gravity) is ahead of the hinge line. It should be located at about 60-65%
    of the length of the control surface from its inner end:

aero34                                                                                                            Credits: http://adamone.rchomepage.com/  http:// 

RC Sailboating 101

A Basic Guide to Wind-Powered Boating                                                                    For anyone who might be interested in RC sailing it can sometimes be difficult to determine such things as what kind of sailboat to start out with, how to set it up and then how to best enjoy it on the water. Only a small percentage of hobby dealers are RC sailing savvy; so, this article will focus-on giving the novice sailor all of the information required to choose his/her’s first wind-powered marine craft.

SIZE/TRANSPORT NOTES
Since RC sail craft are available in many shapes that feature different mast/keel layouts, the beginner will need to first figure-out what size yacht will fit his/her lifestyle. If you have a small vehicle and limited storage space at home, a 20 to 30-inch long hull with an easily detachable mast/sails and a detachable lower keel may best suit your needs. If you choose a larger hull with an equally long mast and keel, it will take-up a lot more vehicle trunk volume; plus, more pre-sail assembly at the lake. Now if your local sailing location has any amount of submerged vegetation, a hull with a shorter-length lower keel will help prevent any weed buildup problems on the underside of the boat. As for the mast/sail layouts available, most kit/RTR boats use a two-piece mast to ease transport and the lower keel mounts in a recess in the hull bottom and it’s retained by a single thumb nut on the deck of the hull.sail1     KIT VS. RTR
Until recently the only way to start out in RC sailing would involve building a kit boat made-up from either a wood, fiberglass or molded plastic hull. Today both plastic and fiberglass RTR yachts are commonplace; so, you can now choose between constructing your first sail craft from a kit or by going with an almost-ready-to-run sailboat. If you’ve had some previous RC car/aircraft experience and have enough workspace, a sailboat kit from such companies as Victor Model Products, Thunder Tiger, Kyosho and Graupner can be built using regular hobby tools, adhesives and paints. To complete the majority of these kits you’ll only need to roundup a stick-style, two-channel surface radio with two servos, one of which will need to be a high-torque model to control the movement of the jib/main sails on the mast.servo1In the event you decide to go with a RTR sailboat, Pro Boat, AquaCraft and several of the kit makers listed above all sell preassembled yachts that are suitable for the novice sailor. In most cases, these RTR boats come from their boxes with only the need to install the pre-rigged mast and sails, attach the keel unit and assemble the hull’s support stand. Adding some batteries to the boat’s radio system will finish-up the yacht’s basic buildup as you can then check/trim the rudder and sail movements on the prepped hull. Once rigged at lakeside, you’ll want to make sure that all of the vessel’s mast and sail control lines are properly attached and tensioned as indicated in the owner’s manual. Then make a quick range check of the powered-up radio system to make sure that the sails and rudder run through their full range of motions. At this juncture you can launch your new sailboat and the fun of learning how to use the wind to “power” your hull can begin.                                                                     servo2A typical yacht’s onboard radio compartment will contain two servos, one of which will only need to be a regular-output unit for rudder control while the other will be a more high-torque servo to properly manage the movement of the sails.    First runs: Depending on the wind’s direction across the water you’ll find that by letting out the sails (moving the left stick on the transmitter upwards) will “catch” the air and this is what’s called running downwind or with the wind. To sail in the opposite direction (towards the wind) you’ll have to steer the hull at an angle to the air which is “tacking” and this technique will have less sail extension than the downwind transmitter stick settings. If you steer the boat’s bow directly into the wind it’ll likely just sit there which is to put the yacht “in irons” and the sailor will have to let the bow swing to one side to again get air in the sails. An important factor to sailing in either wind condition is that you must have enough forward hull speed to maintain the flow of water past the rudder blade as this will allow you to turn the hull whenever needed. It will take some time to master the balance between wind speed, sail settings and hull angles to the wind; but, in only a short time the novice will be able to maneuver his/her yacht no matter which direction the air is moving.                                                                                                   sail2Should you decide to put your yacht in competition, many sailboat clubs include kit and RTR hull classes in their race programs and with their sometimes tight rule packages you’ll have close racing like this in your future.              Sail support: Like all RC activities model sailing is more fun with a group of boaters and it’s not hard to locate other sailing enthusiasts that might reside near your home. The American Model Yachting Association’s website features a nice club directory to help you pinpoint and contact fellow sailors in your area and you can also use the site to help look for any yacht hardware or racing rules that apply to your brand boat. Custom sails, servos, etc. are all found in the suppliers listing while the rules guidelines section will tell just what modifications on your hull should you decide to try your hand at sailboat racing. Many current RTR and kitted sailing hulls regularly compete throughout the country and the sport sailor can learn a lot of useful running tips from those who race the very same sail craft as the one bought by the beginner. The adaptability of most RC yachts make them fun because both the sport and competitive sailor alike can upgrade their hull’s setup to improve the boat’s on water performance and do it for only a small outlay from their RC budget.sail3 When running your boat against the wind, moving the left stick downward on the transmitter will move the sails closer to the center of the hull and by combining this action with running the vessel sideways to the wind you’ll “tack” the sailboat until you’re ready to swing downwind again.                                                                                                                                                                             

SAIL POINTS
• Always apply a drop of CA glue to each rigging cord knot to prevent any mast/sail spillage in breezy conditions.

• When rigging the hull lakeside, keep the boat out of direct winds or simply lay it on the grass to avoid a blow over.

• Remember, a setup sailboat doesn’t like to be anywhere near a running ceiling fan.

• Braided fishing line (with the same outside diameter) can be used to repair/replace any mast or sail lines.

• Be sure to take a folding chair to the lake because the average yacht can sail for a minimum of two hours.

• Since most of a sailboat’s weight is in the keel, carrying it by the lower keel will be the most stress-free way to launch/retrieve it at the lake.                                                                                                                         WRAP UP
Equally suited to anyone looking for a quiet way to unwind from work or to experience a new style of RC boat racing, today’s selection of RTR/kit yachts can easily fit the requirements of the first-time sailor. Capable of conforming to any boater’s storage, transport and local sailing conditions a RC sail craft will only demand a simple cleanup and battery recharging between trips to the lake to enjoy some more wind-driven boating fun.trans1A regular two-stick surface transmitter is used to control sailboats with the left stick being used for sail movement while the right stick sends commands to the hull’s rudder blade.                                                     Credits: Tony Phalen and http://www.rcboatmag.com/  http:// http://

How to Start off With Flying RC Helicopters

Have you ever wanted to fly radio controlled helicopters, but never known how to start? This article contains everything you’ll need to know about flying an RC helicopter. It’s quite easy and fun once you get the hang of it. Read on to see how!                                                    

1

Start off with a 3 channel helicopter. These should be easy to fly and some can be flown inside. Most of these helicopters will be pretty small so do not fly them outside in the wind or else you can end up breaking your helicopter or someone else’s stuff or hurting someone. copter20

2

Don’t fly far away on your first flight and try to have a fair idea of the range.Before purchasing an RC helicopter model or toy make sure that you can use the frequency and that it won’t interfere with anything else or get interfered with. If this happens you can end up not being able to control your helicopter and it will do what it wants (which is most likely to crash without your knowledge). You can avoid this by buying a helicopter with a 2.4GHz radio, which does not suffer from interference by other sources.  copter21

3

Try to avoid buying a tiny little micro helicopter as the tail motors tend to wear out quickly and the batteries don’t last long.                                                                                                      copter22                                                                                                                      

4

Once you have mastered flying a 2 channel or a 3 channel you can upgrade by purchasing a 4 channel type helicopter.

    

RC Tank Wars

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tank3

 

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How to Fly a Quadcopter – The Ultimate Guide

How-to-Fly-a-Quadcopter-The-Ultimate-Guide-Cover-Image

This guide will show you how to fly a quadcopter, step-by-step.

Everyone goes through different struggles when piloting a quadcopter for the first time. UAV flying definitely has a learning curve.

So if you’re having trouble flying your quad, you’re just getting started, or you’re looking to hone your skills — don’t worry.

You’re in the right place.

No matter your quadcopter model, this guide will help you prepare for your first flight, stay safe, get airborne, and learn some basic and advanced quadcopter flying techniques.

Our goal is to give you a guide that will take out all of the guess work – from going through a pre-flight checklist, learning the controls, controlling your quadcopter’s flight pattern, and even some advanced techniques. Have fun!

Definitions

General terms:

Line of site – The pilot can see their quadcopter during flight.

FPV (First Person View) — The pilot can see where they’re flying through the UAV’s camera.

Parts:

Transmitter/Remote Control – The hand-held device that allows you to maneuver the quadcopter and adjust its settings.

Propellers – They spin according to the manual controls of the pilot. The intensity of the spin correlates to the intensity of the quadcopter’s movement.

Camera – Many quadcopters either come with a camera or allow the pilot to attach a camera to them. This is how pilots practice aerial videography and photography. (A camera came in second place when we interviewed UAV experts about their favorite drone accessory.)

(Note: For simplicity’s sake, this article assumes that the left stick controls yaw and throttle, and the right stick controls roll and pitch. Some transmitters allow the pilot to switch these controls based on what’s most comfortable.)

Roll – Done by pushing the right stick to the left or right. Literally rolls the quadcopter, which maneuvers the quadcopter left or right.

Pitch – Done by pushing the right stick forwards or backwards. Tilts the quadcopter, which maneuvers the quadcopter forwards or backwards.

Yaw – Done by pushing the left stick to the left or to the right. Rotates the quadcopter left or right. Points the front of the copter different directions and helps with changing directions while flying.

Throttle – Engaged by pushing the left stick forwards. Disengaged by pulling the left stick backwards. This adjusts the altitude, or height, of the quadcopter.

Trim – Buttons on the remote control that help you adjust roll, pitch, yaw, and throttle if they are off balance.

The Rudder – You might hear this term thrown around, but it’s the same as the left stick. However, it relates directly to controlling yaw (as opposed to the throttle).

Aileron – Same as the right stick. However, it relates directly to controlling roll (left and right movement).

The Elevator – Same as the right stick. However, it relates directly to controlling pitch (forwards and backwards movement).

Maneuvering:

Bank turn – A consistent circular turn in either the clockwise or counterclockwise direction.

Hovering – Staying in the same position while airborne. Done by controlling the throttle.

Figure 8 – Flying in a “figure 8” pattern.

Flight modes:

(Flight modes can typically be adjusted with certain buttons on your remote control/transmitter.)

Manual – Similar to flying a helicopter. Once you tilt the quadcopter (roll) it will not auto-level itself back to its original position. Even if you let go of the stick and it returns to the middle, the quadcopter will stay tilted.

Attitude (Auto-level) – Once the sticks are centered, the copter will level itself out.

GPS Hold – Returns the quadcopter’s position once the sticks have been centered. The same as attitude mode (auto-level) but using a GPS.

Quadcopter Controls

When learning how to fly a quadcopter, the controls will become your bread and butter.

They will become second nature once you know how they act individually and how they interact together to form a complete flying experience.

With any of these controls, the harder you push the stick, the stronger your quadcopter will move in either direction.

When you first start out, push the sticks very gently so the quadcopter performs slight movements.

As you get more comfortable, you can make sharper movements.

There are four main quadcopter controls:

  • Roll
  • Pitch
  • Yaw
  • Throttle

Roll, Pitch, Yaw, and Throttle of a Quadcopter - Image 1

Simple sketch of roll, pitch, yaw, and throttle on a transmitter (left image) and quadcopter (right image).

(Image source: Quadcopters Are Fun)

Let’s go through each of them.

Roll

Roll moves your quadcopter left or right. It’s done by pushing the right stick on your transmitter to the left or to the right.

It’s called “roll” because it literally rolls the quadcopter.

For example, as you push the right stick to the right, the quadcopter will angle diagonally downwards to the right.

Explaining a Quadcopter's Roll - Image 2

Example of a quadcopter rolling left and right. Notice the tilt of the quadcopter and the angle of the propellers.

(Image source: Best Quadcopter Spot)

Here, the bottom of the propellers will be facing to the left. This pushes air to the left, forcing the quadcopter to fly to the right.

The same thing happens when you push the stick to the left, except now the propellers will be pushing air to the right, forcing the copter to fly to the left.

Pitch

Pitch is done by pushing the right stick on your transmitter forwards or backwards. This will tilt the quadcopter, resulting in forwards or backwards movement.

Explaining a Quadcopter's Pitch - Image 3

Example of a quadcopter pitching forwards and backwards. Note that this view is from the left side.

Yaw

Yaw was a little bit confusing for me in the beginning. Essentially, it rotates the quadcopter clockwise or counterclockwise.

This is done by pushing the left stick to the left or to the right.

Check out the video below for an example.

(Watch from 3:00 to 3:40 and pay attention to how he adjusts the sticks.)

 

Yaw is typically used at the same time as throttle during continuous flight. This allows the pilot to make circles and patterns. It also allows videographers and photographers to follow objects that might be changing directions.

Throttle

Throttle gives the propellers on your quadcopter enough power to get airborne. When flying, you will have the throttle engaged constantly.

 

To engage the throttle, push the left stick forwards. To disengage, pull it backwards.

Make sure not to disengage completely until you’re a couple inches away from the ground. Otherwise, you might damage the quadcopter, and your training will be cut short.

Important note:

When the quadcopter is facing you (instead of facing away from you) the controls are all switched.

This makes intuitive sense…

  • Pushing the right stick to the right moves the quadcopter to the right (roll)
  • Pushing the right stick forward moves the quadcopter forward (pitch)
  • Pushing the right stick backward moves the quadcopter backward (pitch)
  • And so on.

So pay attention to that as you start changing directions. Always be thinking in terms of how the quadcopter will move, rather than how the copter is oriented towards you.

Getting to Know Your Remote Control/Transmitter

A transmitter is a hand-held controller that lets you pilot your quadcopter and control its flight pattern. When you make an adjustment with the sticks, it sends a signal to your copter telling it what to do next.

Check out this picture describing each part of the transmitter:
How-to-Fly-a-Quadcopter-Trasmitter-Labels-Image

(Image source: Alibaba)

Right Stick

The right stick controls roll and pitch.

In other words, it moves your quadcopter left/right and backwards/forwards.

Left Stick

The left stick controls yaw and throttle.

In other words, it rotates your quadcopter clockwise or counterclockwise, and it adjusts the height at which you are flying.

Trim Buttons

Each control has its own trim button, as you can see from the image below.

Trim Buttons on a Transmitter - Image

(Image source: Quadcopter 101)

When you first push your throttle to get your quadcopter off the ground, you may notice that the UAV automatically tilts and flies to one direction (or multiple).

This happens when the controls are unbalanced. To balance them out, certain controls need to be trimmed.

Check out the beginning of this video, where the pilot trims a few of his controls:

(Watch from 0:47 to 1:07)

 

If this happens, you can use the corresponding trim button to adjust the control’s natural intensity. This will stabilize the copter when pushing the throttle.

An Overview of the Main Quadcopter Parts

When learning how to fly a quadcopter, it’s important to understand the machine you’re commanding.

If something goes wrong, you want to be able to diagnose and fix the issue. You also want to understand the capabilities of each part and how they play into flying a quadcopter.

Here are the main parts of a quadcopter:

  • The frame
  • Motors
  • Electronic Speed Control (ESC)
  • Flight Control Board
  • Radio Transmitter and Receiver
  • Propellers
  • Battery and Charger

The frame connects all of the other components. For a quadcopter, it’s shaped in either an X or a + shape.

If you’re building your own quadcopter, you want to consider the size and weight of the frame and how it will affect your flying experience.

The motors spin the propellers. A quadcopter needs four motors, because one motor powers a single propeller.

The higher the kV, the faster the motor will spin. Kv is often quoted in RPM per volt, which means that a 1000 Kv motor on a 10V supply will rotate just under 10,000 rpm at no load.

Electric Speed Controls (ESCs) are wired components that connect the motors and the battery. They relay a signal to the motors that tells them how fast to spin.

At any one time, each of your motors could be spinning at different speeds. This is what lets you maneuver and change direction. It’s all conducted by the Electronic Speed Controls, so they’re very important.

The Flight Control Board is the “commander of operations”. It controls the accelerometer and gyroscopes, which control how fast each motor spins.

The radio transmitter is your remote control, and the receiver is the antenna on the copter that talks to the remote control. When you make an adjustment on the transmitter, the receiver is what understands that adjustment and sends it to the rest of the quadcopter system.

A quadcopter has 4 propellers, and each one helps determine which direction the quadcopter flies or whether it hovers in place.

The battery is the power source for the whole quadcopter. This needs to be charged and recharged, because without a battery, you cannot fly your quadcopter.

The charger charges your battery so you can take multiple flights.

(Pro tip: We recommend buying multiple batteries. This way, you won’t have to wait for the first battery to charge in order to take more flights. You can charge the first battery while you insert the second, third, fourth one, etc.)

The Pre-Flight Checklist (Do NOT Skip This)

Going through a pre-flight checklist will keep you and your copter safe.

It will also make sure you don’t waste time fixing components and getting things ready, when you could be having a blast flying your quad.

Here’s a checklist you can use before each flight:

  • If you have a camera, check that you have your micro SD card inserted.
  • Make sure the transmitter battery is charged.
  • Make sure the quadcopter battery is charged.
  • Insert the battery.
  • Make sure the battery is inserted securely.
  • Make sure each propeller is secure.
  • Check that there are no loose parts on the quadcopter.
  • Check for missing or loose screws.
  • Turn on the transmitter.
  • If your copter needs to calibrate and get satellite lock, wait until it finishes.
  • Make sure there is enough room for launch and flight.
  • Make sure the throttle (left stick) is all the way down.
  • Turn on the transmitter.
  • Back away 3 or 4 steps (or to a safe distance).
  • Keep facing the quadcopter the entire time.
  • Keep a direct line of site at all times when flying, so you can always see your quadcopter. You want to keep a direct line of site so you know when you’re about to crash. Also, sometimes, quadcopters can fly out of the range of the transmitter’s signal, which can cause your copter to fly off on its own (bye bye quadcopter). Keep the transmitter’s range in mind, and don’t let your quadcopter fly out of that range.

How to Fly a Quadcopter – Choosing a Place to Learn

Any UAV pilot will tell you that learning to pilot a quadcopter in an enclosed space is asking for something to go wrong – either with you, your belongings, or the drone itself.

As you get more experienced, and your control becomes natural, flying in tight spaces will be a cinch.

But as a beginner, choose a place that will minimize the impact any mistakes might have.

We suggest starting out in a large, open space, such as a park or a field. Many people prefer to learn on grassy ground, so if the quadcopter needs to make a crash landing, it will at least have some sort of cushion.

Next, stay away from people or animals. Any crashes could cause serious injury.

And finally, wind can be your worst enemy when learning the nuances of flying. To reduce the chance of flying in the wind, try to fly in the morning.

Important Safety Precautions

Quadcopters are basically flying lawnmowers.

They can be dangerous if not operated carefully.

Here are some quadcopter safety precautions to keep in mind:

  • If you’re about to crash into something, turn the throttle down to zero, so you don’t potentially destroy your quadcopter, injure somebody, or injure yourself.
  • Keep your fingers away from the propellers when they’re moving.
  • Unplug/take out the battery of the quad before doing any work on it. If it turns on accidentally and the propellers start spinning, you might have a tough time doing future flights with missing fingers.
  • If you’re a beginner learning to fly indoors, tie the quadcopter down or surround it by a cage.

    How to Get Your Quadcopter Off the Ground

    Alright! Now that you understand the controls and you’ve taken all of the right safety precautions, you’re ready to fly.

    To get your quadcopter in the air, the only control you need is the throttle.

    Push the throttle (left stick) up very slowly, just to get the propellers going. Then stop.

    Repeat this multiple times and until you’re comfortable with the throttle’s sensitivity.

    Slowly push the throttle further than before, until the copter lifts off the ground. Then pull the throttle back down to zero and let the quadcopter land.                                                                               (Watch from 1:15 to 1:40)

     

    Repeat this 3-5 times. Notice whether the copter is trying to rotate left or right (yaw), move left or right (roll), or move backwards or forwards (pitch).

    If you notice any movements happening without you making them happen, use the corresponding trim button to balance them out.

    For example, if you notice the copter moving to the left when you push the throttle, adjust the “roll” trim button next to the right stick.

    Keep adjusting the trims until you get a relatively stable hover off the ground by only using the throttle.

    Congrats! You know how to get your quadcopter airborne.

    Now, let’s learn how to hover in mid-air.

    How to Hover in Mid-Air and Land

    To hover, you will use the throttle to get airborne. You will then use small adjustments of the right stick to keep the quadcopter hovering in place.

    You may also need to adjust the left stick (yaw) slightly, to keep it from turning.

    Use the throttle to get the copter about a foot to a foot-and-a-half off the ground.

    Make tiny adjustments with the right stick (and the left, if necessary) to keep the copter hovering in position.

    When you’re ready to land, cut back the throttle slowly.

    When the quadcopter is an inch or two off the ground, go ahead and cut the throttle completely and let the UAV drop to the ground.

    Repeat this until you get comfortable hovering off the ground and landing gently.

    Flying Left/Right and Forwards/Backwards

    To fly a quadcopter left, right, forwards, and backwards, you will need to hold the throttle at a steady rate to keep it airborne. You will then use the right stick to maneuver the quadcopter in the direction you want it to go.

    First, bring your copter to a hover.

    Push the right stick forward to fly it a couple feet forward.

    Pull the right stick back to bring it back to its original position.

    Now, move it further backwards a couple feet, and return it to its original position.

    Push the right stick to the left to move your copter a couple feet to the left.

    Move it back to its original position, then fly it a couple feet to the right.

    If it starts to rotate (yaw), adjust the left stick to the left or right to keep the copter facing the same direction.

    (Pro tip: When you move in either direction, you will probably notice the quadcopter dropping in altitude. To keep the copter at the same altitude, push the throttle and give it more power whenever you turn or move.)

    How to Pilot Your Quadcopter in a Square Pattern

    You’ve gotten off the ground, and you know how to fly a quadcopter in the four basic directions.

    Now, it’s time to combine these skills and start flying in patterns. This will help you get a feel for simultaneously engaging the controls.

    To fly in a square pattern, keep the quadcopter facing away from you the entire time.

    Push the right stick forward (pitch) and fly forward a couple feet. Then, return the right stick to the middle and hover in place.

    Then push the right stick to the right (roll) and fly to the right a couple feet. Then, hover in place for a few seconds.

     

    Pull the right stick backwards and fly backwards a couple feet. Then, hover in place for a few seconds, and push the right stick to the left and return the quadcopter to its original position.

    You’ve just flown in a square! Keep doing this until you get comfortable with it, and then move on to our next pattern – flying in a circle.

    How to Fly a Quadcopter in a Circle

    This is where you will hone your simultaneous control skills.

    To fly a quadcopter in a circle, you will use pitch, roll, and throttle at the same time.

    As usual, use the throttle to get airborne. Then, decide whether you want to fly clockwise or counterclockwise.

    For this example, we’ll assume you’re flying clockwise (to the right).

    Keep the quadcopter facing away from you, and push the right stick diagonally up and to the right. This will engage both pitch and roll at the same time, and start flyinging the quadcopter in a circle to the right.

    After a couple feet, start rotating the right stick more to the right, so you engage more roll. This will start maneuvering your quadcopter to the right.

    After a few more feet, start rotating the right stick diagonally to the bottom right, and continue to circle the right stick around until the copter returns to its original position.

    Try changing directions, and slowly rotating the right stick to fly in a circle. If you notice the quadcopter starting to rotate and face different directions, adjust the quadcopter’s yaw by pushing the left stick to the left or right.

    How to Rotate (Yaw) Your Quadcopter

    To rotate your quadcopter, use the throttle to get airborne.

    Once at a comfortable hover, push the left stick in either direction. This will rotate the quadcopter in place.

    Rotate it 360 degrees. Then push the left stick in the opposite direction and rotate it 360 degrees the other way.

    Keep doing this until you’re comfortable with it.

    Flying a Quadcopter Continuously

    Flying a quadcopter continuously requires you to rotate and change directions simultaneously.

    This will take some getting used to, because the quadcopter will be facing different angles in relation to how you’re facing, so you will need to pay close attention to how each movement of the sticks will affect the quadcopter’s flight.

    First, take off and hover.

    Rotate (yaw) your copter to a slight angle.

    Use the right stick to fly it left/right and forwards/backwards. Get comfortable flying the quadcopter while it faces a different direction.

    Rotate it to another angle, and use the right stick to maneuver it again.

    Keep doing this until you’re comfortable flying at different angles.

    To fly continuously, slowly push the right stick forward.

    As you’re pushing the right stick forward, push the right stick slightly to the left or to the right at the same time.

    Fly in different directions by pushing the right stick forward (pitch) and adjusting it left and right, and using the left stick (yaw) to change the direction the copter is facing.

 

Then, try adjusting the quadcopter’s height by moving the left stick forward and backward (throttle).

Congrats! Now you know how to fly a quadcopter with continuous movement.

Keep practicing until you can direct your quadcopter at will. Then, move on to the next section, where we’ll discuss different milestones for you to shoot for.

Different Milestones to Pass

Use these milestones to keep you organized during the learning process.

They will help you gauge where you’re at and what you should be going for next.

  • Learn how the four main quadcopter controls – roll, pitch, yaw, and throttle – affect a quadcopter’s movement.
  • Understand the parts of your quadcopter and what each of them does.
  • Prepare a pre-flight checklist and go through it before each take off.
  • Understand the safety precautions.
  • Use the throttle to get airborne, and make any necessary adjustments using the trim buttons.
  • Get comfortable hovering in mid-air and gently landing your quadcopter.
  • Take off to an altitude of 3 feet and land in the same position.
  • Take off to an altitude of 3 feet and spin the UAV around 180 degrees.
  • Get comfortable flying your quadcopter left/right and forwards/backwards.
  • Learn how to fly a quadcopter in a square pattern.
  • Learn how to fly a quadcopter in a circle.
  • Learn how to rotate (yaw) a quadcopter.
  • Learn how to fly a quadcopter continuously.
  • Do all of the above, but at an altitude of 25 feet.

Beginner’s Quadcopter Flying Techniques

Here are some beginner flying techniques for you to master:

  1. Hover in place.
  2. Hover and rotate the quadcopter.
  3. Rotate the quadcopter to different angles, and fly it left/right and forwards/backwards until you’re comfortable flying a quadcopter without it facing the same direction as you.
  4. Fly your quadcopter in a square pattern.
  5. Fly your quadcopter in a circle.
  6. Fly at different heights.
  7. Pick two targets on the ground, and repeatedly land, fly, and land on each one.

Check out this video for an example of #7:

(Watch from 4:33 to 4:57)

And if you’re still struggling to get the hang of it, Korey Smith from My First Drone put together a useful bank turns video as well.

Next Steps

Congrats on finishing our “How to Fly a Quadcopter” drone pilot training guide! We hope it gets you on your way to flying a quadcopter like a pro.                                                                                                               Credits: http://uavcoach.com/  http:// http://

Owning And Operating A Nitro Powered Radio Controlled Car Or Truck

Nitro RC Cars

by :nitro1Owning and operating a nitro powered radio controlled car or truck adds an element of excitement and realism to this hobby above and beyond that provided by the electric RC counterparts. Unfortunately, it also poses some unique challenges. The one question that is posed to me the most often is ‘how do I start a gas powered RC car’?

Well, first of all, you need to assemble a few necessary items. These can be obtained either individually, or purchased as a package with or without your radio controlled car or truck. You will need the correct nitro fuel, a glow igniter, batteries for your radio transmitter and receiver, and a small screwdriver.

Have your glow igniter fully charged and ready to use. Make sure you have installed batteries in your controller (transmitter) and the car’s on board receiver. Verify that they are functioning properly by operating the steering, throttle and brake. After all, you want to be able to control your RC car once it is running! Fill the car’s fuel tank with the proper nitro fuel. Be careful  fuel is extremely flammable and toxic! Check with your engine’s manufacturer or your local hobby shop to make sure you are using the recommended nitro mix. 20% is the most popular. OK? Now we are ready to fire her up.

Clip the glow igniter to the glow plug located in the top of the engine cylinder head. Rotate the engine by whatever means your car or truck uses such as manual pull recoil, on board electric starter, drill operated shaft starter, or portable starter box. You may have to ‘choke’ the engine to initially supply fuel to the carburetor. You can easily do this by placing a finger over the exhaust outlet. Watch for fuel movement through the fuel hose so you know when fuel has reached the carburetor. You don’t want to flood the engine!

Once the engine has started and is running smoothly, you can remove the glow igniter. Drive easy for a few minutes until the engine warms up a little. After warm up you may find it necessary to adjust the carburetor high speed needle, low speed needle, or idle speed set screw to maximize performance.

This might all seem intimidating to you, but it really isn’t hard to learn with a little practice and patience. The sound of that high performance nitro engine springing to life makes it well worth the effort!
sources www.hobbiedown.com and actionvillage.com

Step 1: how to drive you Gas RC car.                                                   nitro2nitro3                      I no most people think its easy to drive but most do not.
Step1
Realize that your controller works just like the steering wheel on your regular car. When you move it to the left, your RC car moves to the left and when you push the controller to the right, your car moves to the right.
Step2
Drive as fast as you can the first few times you take your RC car onto a new track. This will help you get a feel for the track without worrying too much about making a mistake.
Step3
Stick to the middle of the track instead of trying to hug the edges. Your lap times might not be as good, but at least you won’t drive your RC car right into one of the track barriers.
Step4
Look for lines or the areas of the track where more experienced racers drive their cars. This should give you an idea on how to lower your lap times.
Step5
Draft with other cars just as you would if you were racing NASCAR instead of driving an RC car. Not only can you increase your speed, but you can also see where other cars are running and what spots drivers are avoiding.
Step6
Be consistent any time you drive your RC car. The more time you spend racing and practicing, the better you’ll get.
ive but most dont.

Step 2: gas rc car safey                                                                              nitro4nitro5nitro6Safety Issues and Rules for Responsible RC Car & Truck Operation
Be a safe, courteous, and responsible RC car or truck owner and operator. Protect yourself, those around you, and your RC vehicles by using common sense and following certain guidelines for safe use of radio controlled cars, trucks, motorcycles, tanks, bulldozers, and other RC ground vehicles.
Control Your Controller
Before you run your RC: Controller on first, vehicle on second. After you run your RC: Vehicle off first, controller off second.
Choose a Safe Area to Operate Your RC
Choose a safe, open area to operate your radio controlled vehicle. Avoid people and busy streets.
Check Your Frequency
Check your frequency and make sure no one in your operating area is using the same frequency at the same time you are.
Check for Obstacles Before Operating Your RC
Survey the area that you will be driving in and make sure it is clear of undesired obstacles… i.e. stumps, large rocks, puddles of water, or other obstructions.
Avoid Spinning Wheels
Do not pick up your vehicle while the tires are still moving.
Handle and Store Nitro Fuel Safely
Nitro fuel is highly flammable. Avoid open flames — including smoking — around nitro containers. Mark your container for identification.

Step 3: Nitro RC Operation And Maintenance                               nitro7Nitro RC Operation and Maintenance
A nitro RC has many more parts than most electrics. There are also specific operational and maintenance requirements from engine tuning, to break-in, to after-run maintenance. Learn how to keep your nitro RC glow engine at peak performance levels. And when your nitro engine won’t run, do some troubleshooting to isolate and fix the problem.
Nitro Troubleshooting @
Nitro Engine Break-in Procedure
Proper nitro engine break-in is critical for long-lasting performance of your RC. Every new nitro engine should undergo a break-in procedure. If you do nitro engine break-in properly, the up-keep on your RC vehicle is less costly than if the procedure is done hastly and incorrectly. Be patient.
Adding After-Burn Oil
After running your RC for a while you have to perform after-run maintenance. Part of that after-run maintenance includes lubricating the pistons and all the internal parts by adding after-burn oil to the engine cylinder head.

Step 4: Carb ajusting.nitro9nitro8                  How does the carburetor work and how do I adjust it?

We got the theory part of the engine under control. We can’t really tune a piston or adjust a crank-shaft, at least not in your every-day engine maintenance and adjustment. So without further delays lets dive into the 2nd phase of this project& The Carburetor. What good is a 1.2 HP engine if you can’t keep the dam thing running? That’s exactly my point, it does not matter how little horse power your engine has, if it can stay running for the entire duration of the main then you will have a real good change to at least get one of the top three positions. They say that before you can win a race -first you must finish. The first part of finishing a race it to have a well tuned engine. In this article we will go over how a carburetor works and how to adjust it. Without any further delays lets get busy!

Carburetor Theory

The carburetor has one main function, to regulate engine speed. It accomplishes this by metering the amount of air and fuel as required, to sustain combustion per the input of the throttle servo. Thus for a low-speed idle you would have a small amount of air and fuel entering the engine. This would in effect lower the chemical energy entering the combustion chamber and thus lessen engine power and subsequently lower the RPM. As we open the throttle the carb will allow more air and fuel into the combustion chamber, thus increasing engine power and RPM’s (revolutions per minute). Now that we know what the carb. has to do lets explore the underlining fluid mechanic properties that allow the carb to function effectively at different throttle settings.

The Venturi-Effect

What allows the carb to pull fuel from the fuel tank is the venturi-effect. This states that in a converging funnel the entering fluid velocity increases as it passes through a reduction in the funnels throat diameter. This increase in fluid velocity decreases the localized pressure at the venturi throat to below atmospheric pressure. This low pressure region is precisely where fuel enters the carburetor throat. This is what allows the engine to “suck” fuel from the gas tank. The truth is that the venturi-effect is all that is needed for the engine to get fuel. Pressurizing the fuel tank is really only done to decrease the effects of fuel level on the mixture setting of the carburetor.

Fuel Metering Devices

The venturi-effect draws fuel from the tank but does little to regulate it’s flow. It’s true that as the engine accelerates the amount of air that moves through the engine increases. The increase in air velocity also increases fuel flow into the induction port, this helps the engine self regulate the fuel up to a certain point.

This is not the only means for the carburetor to meter air and fuel. Engines need a metering device to help regulate the amount of fuel that enters the carburetor. This is accomplished with an adjustable orifice, typically we call them needles or jets. Most engines have a second adjustable needle that helps regulate fuel at low throttle settings. By adjusting these two needles we can control the transition from low to high speed operation of the engine.

How do we adjust a carburetor?

The carburetor is typically adjusted with a long flat-head screw-driver. Carb adjustments are then done by rotating the needled in, our out of the needle seat. The idle speed is adjusted by a screw at the base of the carburetor. This allows the throttle barrel to only close to a preset position.

The carb has three main adjustments that allow you to set the following:

1. Set the idle speed.

2. Set the mixture at idle (Adjustable on 2-needle carbs only).

3. Set the high speed needle mixture and control engine temp

How to make carburetion adjustments:

Idle Speed:

The throttle stop screw or idle-speed screw (same thing) determines how far the carb barrel will be able to close when the servo is in the neutral position. Typically you set the servo/throttle linkage so that the carb will go from fully open when the trigger is fully pressed to fully closed when the trigger is in neutral. Then you would adjust the idle-stop/speed screw so that there is a 1-2 mm gap when the servo is in the neutral position. You might need to readjust the spring collars on the throttle linkage to force the throttle arm against the idle speed screw.

Tip#1: If you completely mess up the carb setting and you want to go back to the factory recommended needle setting then you must have the carb fully (Yes I mean fully closed) before you can set the low-speed needle to whatever turns the engine manufacturer suggests. Before you close the carb fully back the low-speed needle a bit to make sure you wont put un-needed stress on the needle seat.

Tip#2: There should be no speed change whatsoever when the car is in idle and when you hit the brakes. If the engine’s RPM drop either your linkage isn’t set right or the idle-speed screw is set too loose. Tighten clockwise until the carb barrel doesn’t move when you go from neutral to full brakes.

Tip#3: Some RTR kits have servo horns that are too small. There is not enough servo throw to open the carb barrel, if you use servo trim to be able to open the carb fully, then when you go to neutral the carb doesn’t close enough. To compensate for this the novice engine tuner opens up the low speed needle to drop the engine RPM so the car will stay still when at idle… The drawbacks of correcting the linkage problem with the mixture control is that now the low-speed is too rich and the car won’t idle for more than a couple of seconds before the engine sputters and dies.

To fix this problem you need to get an after market servo horn that is larger yet still fits your particular servo brand. Now you can go from fully open to fully closed, without using trim. Now you wont have to compromise the carb settings because of lack of servo throw.

Low-Speed Needle:

At this point you would start the engine warm it up and commence tuning. Adjust the low-speed needle clock-wise until the engine doesn’t sputter when at idle. You want a fast idle, if the car wants to move forward a lot, then turn the idle-speed screw counter clock wise to lower RPM until the engine just barely want to engage the clutch. It may take a little time to get the settings right.

Remember you want the fastest idle you can get away with. It will make the engine more stall proof. Some engine will overheat if the idle isn’t rich enough, you need to experiment to determine what’s the right setting for your particular engine. When every thing is set right the engine will be able to idle through an entire tank without missing a beat.

High-Speed Needle:

The high speed needle will control fuel flow into the carb from 1/2 to full throttle. Typically the high speed needle is set to allow the engine to reach it’s peak power point, then you open the needle slightly and go racing. On very hot and humid days you will probably have to make a compromise in the tuning department. For most this will mean you will richen up the high-speed needle to lower engine temperatures to acceptable levels. Everyone has their own interpretation of what an acceptable engine temperature is, for me anything under 260 is acceptable. Going higher will typically mean shorter engine life-span and less reliability.

Step 5: Glow Engine tuning basics                                                      nitro10nitro11                        Understanding Your Engine
The first and foremost consideration when attempting to tune your glow engine is understanding the basic parts and their functions. By understanding the fundamentals, you can better tune your engine for maximum performance while at the same time, expanding the life of your engine.

Carburetor
The carburetor is the mechanism that mixes fuel and air in very specific proportions and passes it on to the engine through the vacuum intake. The natural operation of the engines causes of flow of gases to pass through the engine (through the carburetor) and out the exhaust manifold and on to the pipe or muffler. The exact mechanism for this is unimportant for the scope of this tutorial, however it is important to realize that air and fuel pass into the engine by this vacuum method. Depending on how you adjust your carburetor, you can either adjust how much of this gas/air mixture reaches the engine and to what proportion of gas to air passes on to the engine. By reducing the amount of fuel per volume of air, you are making the mixture “lean” and by increasing the amount of fuel, you are making the mixture “rich”.

The two types of carburetors are slide and barrel. The old-style barrel carburetors still dominate the market because of their simplicity in design and because of the tendency for designers to hang on to legacy design. These have been around since the beginning of glow-fuel planes. They control gas/air flow by rotating a barrel with a hole cut in either side that allows varying amounts of gas/air mixture to flow through the carburetor as the hole opening enlarges to the venturi (air shaft down the center of the carb body).

Idle-Speed Adjustment
This is the most basic and easy to understand part of tuning your carburetor. This spring-tensioned screw limits the closure of the barrel aperture. Although this doesn’t affect the mixture of the fuel it does affect the idle speed. The more closed the aperture is, the slower the idle, the larger the aperture, the faster. As you close this aperture up and the idle speed decreases, you will eventually (sooner than later) stall the engine out. In order for the engine to run, it must have enough inertial energy built up in the engine and flywheel to carry it through the entire ignition cycle. Generally speaking, you want to adjust this down to the slowest idle, just before it begins to stall.

Low-End Mixture Adjustment
This adjusts the fuel mixture at or near idle. Some engines lack this low-end mixture valve for reasons of simplicity, however this makes accurate tuning difficult.

For barrel carbs, this mixture valve is generally found where the throttle-arm pivots. Some are countersunk, others are clearly visible from the outside. On slide carbs, they are generally found on the opposite side of the carb from the throttle slide shaft (has an accordion billow type rubber boot over it) next to, but below the fuel-inlet and high-end mixture valve.

High-End Mixture Adjustment
Also known as the Main Needle adjustment, this is the primary fuel mixture adjustment. This is generally found on the top end of the engine, typically next to where the fuel line goes into the engine. Some are flat-head screws like the low-end mixture, others are hand adjustable valves.

Tuning Basics

It’s important to understand that there is a reputation for glow-engines to be difficult to tune. This is a common error in thinking. With a little bit of know-how, tuning a glow engine can really be a simple, pain-free process. People that don’t properly understand the basics can easily become frustrated by what should be a simple, straightforward process. Here’s how you do it:

Dialing it In
For the purpose of this tutorial we are going to make some basic assumptions. First, we’re going to assume that the rest of your car or truck is properly functioning and that you have everything ready to go. Second, we’re going to assume that you are able to start your engine and that it at least runs for a second or so.

The first place to start with dialing in your engine is to make sure that you have your idle-speed properly adjusted. Your engine manual should give you specific instructions on setting the aperture gap to the minimum size. It’s important that we get this resolved before continuing on. If your engine can’t get enough air/gas flow then it won’t start/run. A clockwise rotation opens the aperture and increases the idle RPMs, a counterclockwise slows it down.

Second, you should tune the low-end mixture valve. This is done before the high-end (main needle) adjustment because an improperly adjusted low-end can affect the high-end performance. Like most mixture valves, clockwise rotation will “lean” the mixture and a counterclockwise will “richen” the mixture.

To determine whether the low-end mixture requires tuning, allow the engine to warm up completely, and then allow it to idle, uninterrupted for one full minute. If the engine continues to run after the minute is up then your low-end mixture is correct and you’re ready for the high-end adjustment. If it dies on you then there are two possibilities; either you are running too rich or too lean. To determine which is the case you must listen for how the engine dies in its idle test.

If the engine’s RPM’s rev up at the last second and then the engine dies than you are running too lean. To correct this, turn the low-end mixture screw counterclockwise (out) 1/8 of a turn (always make adjustments in 1/8 turn) and retry the idle test.

If, on the other hand, it begins to wind down and you notice a change in how the exhaust sounds in the last few seconds, then your engine is running too rich. To correct this, turn the low-end mixture screw clockwise (in) 1/8 of a turn and then retry the idle test.

Once you have passed the idle test and are able to idle for one full minute (after first warming the engine up, of course) you are ready to continue on. You may have to repeat the above process a few times until it is properly set. Remember, only adjust the screw 1/8 of a turn. It’s far too easy to go too far with the adjustment. Setting changes don’t always take effect immediately. You may have to run your engine for a few minutes for the full effect to take place.

Now that you have dialed in your low end, any carb mixture problems can be isolated to the high-end (main) mixture adjustment.

Acceleration is the tell-tale sign of how to tune your high end. If you hit the throttle and it takes off suddenly but then suddenly dies or loses power then you have your main mixture set too lean. Try backing (counterclockwise) the main mixture needle out 1/8 of a turn and retry. If it bogs immediately when you hit the throttle (sounds like it’s choking), then it’s most likely running too rich. Try leaning the mixture out by screwing the main mixture valve in (clockwise) 1/8 of a turn.

The more accurate way of really dialing in the top-end is to take the engine’s temperature. A properly tuned engine should run between 210� and 220� Fahrenheit. This can only really be ascertained by using and infra-red thermometer such as the type used by automotive mechanics. On-board or direct-transfer types that measure the heat from the head are inaccurate because, assuming the head is properly dissipating heat, it would reflect a lower than accurate temperature as a majority of the heat energy would be dissipated from the exposed surface of the head. By “looking” at the temperature near the core (actually, area immediately surrounding the glow plug) the temperature can be more accurately read.

The cheap but easy alternative would be to drop a bead of water down the head on the glow-plug and see whether it boils off. If it slowly simmers than it probably is running right around 212�. If it boils to quickly then it’s probably too lean and needs to be richened. If it just sits there and doesn’t boil at all, then its running too rich and needs to be leaned out.

An engine that is running too lean will run hotter and exceed the 220� degree limit. This can significantly reduce the life of your engine. Although it may be tempting to run your engine as lean as possible (does give a short-lived performance boost), this should only be done if you are very wealthy and like swapping engines out every race. There is no quicker way to kill and engine, honest. This is simply because as you lean the engine out, it gets less fuel to the engine, and more importantly, less lubricant. Since glow fuel is the only means of lubrication for your engine, the lack of it means certain death to your powerplant.

A few final do’s and don’ts…

    • Give your adjustments time to take affect. Remember that most adjustments won’t be immediately noticeable. You need to drive your engine through it’s full range for at least a minute. Make sure you make adjustments in 1/8 turn adjustments only!
    • Always run on the rich side. It’s far better to take a slight performance hit than to turn your engine into a paper weight. Running too lean may give you a temporary thrill, but it’s short lived. Your engine must get the proper amount of lubrication at all times.
    • Changes in temperature affect your tuning! Whenever the outside temperature changes you will most likely need to re-adjust your engine. Warmer temperatures require a leaner setting where colder temperatures require a richer setting.

 

I hope that this info gets you on the right track. If all fails, it’s always a good idea to get expert advice from the vets down at your local track. However, be aware of the guy that’s too eager to give you advice on how to get that extra performance boost out of your engine. Unless he or she plans on buying your next engine, I would be weary of any such advice.

Good luck!

Step 6: Engine Maintenance.                                                                nitro10nitro11                         day-to-Day Maintenance

There are three basic steps one should take on a day-to-day basis to ensure you continue getting the most from your engine:

1. Keep your engine clean on both the inside and outside. By keeping pariticles of dirt out of the workings of your engine, the operating surfaces will remain smooth and therefore less wear and better performance will result. Always use a fuel filter between your tank and the engine to catch any particles in the fuel. When operating in dusty conditions, use an air filter on your carb to keep particles out of your air intake. When done for the day, use a motor spray to clean off the dirt from the outside of the engine, especially the carb and linkages.

2. Use an after run at the end of the day. Since fuel contains elements that are hydroscopic (they abosrb water), any fuel left in an engine will attract moisture and therefore contribute to rust. It is important that you run the engine dry after your last flight or run to remove the last of the raw fuel. This can be done by simply pulling the fuel line from the engine and letting the engine run out. Apply several drops of after run oil into your carb and turn the engine over to ensure the oil gets distributed throughout the inner workings, coating the metal and protecting it from rust.

3. Ensure all of your nuts and bolts are tight. Between flying or running sessions, check that all of your bolts, such as the head bolts, backplate bolts, muffler bolts, engine mounting bolts, and carb mounting screws, are tight. Also, check that prop nut to ensure you won’t be launching a spinning prop on your next flight. An over revved engine, particularly a four stroke, can cause damage without the load of a prop or flywheel.

End of Season Maintenance

When the flying season is over, a small amount of engine care can ensure a successful beginning to the following season.

Clean Engine with Motor SprayRemove your engine from the model and give it a visual checkessentially perform the same checks you would do at the end of a day. Make sure that all bolts are in place and tight. It is not necessary to disassemble the engine unless you feel that there is internal damage or that the bearings require replacing. Replace any stripped bolts or rough running bearings. Clean the entire engine with motor spray to remove all dirt. Finally, load up the engine with after run oil, turning it over to ensure that all moving internal parts are covered. This will go a long way to reducing the chance of your engine rusting in the off season. Store the engine in a baggie to keep the dirt out and the oil in!
Beginning of the Season

The first thing to do before re-installing your engine is to replace the plumbing in your model. Remove the fuel tank and take out the rubber stopper and all brass and silicone tubing. There are components in the fuel that break down brass over time and if left, the tubing will eventually crumble or at the least allow air to enter the line. Clean the residue from the tank itself with a bit of isopropyl alcohol and then install a new rubber stopper assembly with new brass and silicone tubing. Reinstall your tank.

Take your engine from its baggie and use spray motor cleaner to get the after run off the outside of the casing. Re-install your engine to the model. When you are ready to run your engine, remove the glow plug and flush fresh fuel through the engine, turning it over with your thumb over the carb. This will clear out the storage oil. Replace the plug and start your engine as normal. http://  http://Amazon.com – Read eBooks using the FREE Kindle Reading App on Most Devices

Off-Road RC Car Tuning Guide

Need More Steering?
• Batteries – Move batteries towards the front of the vehicle.
• Front Shock Mounting – Move the lower shock mount towards the outside
• Front Camber Link – Longer camber links increase steering
• Front Ride Height – Lower the front ride height
• Rear Ride Height – Raise rear ride height for more high speed steering
• Rear Shock Mounting – Move upper mount towards outside
• Wheelbase – Lengthen the wheelbase for more steering
• Rear Toe-in – Decrease rear toe-in
• Ackerman – Use less Ackerman for more sensitive steering                                                                               offroad1                                                                                                             Need More Traction?
• Batteries – Move batteries towards the rear of the vehicle
• Rear Ride Height – Lower rear ride height
• Rear Camber – Less camber (0 -1 deg.)
• Camber Link – Longer camber links
• Rear Shock Mounting – Move upper mount towards the inside
• Wheelbase – Shorten the wheelbase
• Rear Toe-in – Increase rear toe-in
• Slipper – Loosen slipper so wheels don’t spin as much                                                                                             offroad2                                                                                                                 Need Better Jumping?
• Shock Oil – If bouncing too much or bottoms out over jumps, use heavier oil
• Shock Pistons – If bottoming out over jumps, use smaller hole pistons
• Rear Shock Mounting – If bottoming out over jumps move upper mount towards he outside
• Battery Position – If nose high during jumps, move battery forward, move rearward if nose is down during jumps
• Weight – Add weight to nose if it’s too high during jumps                                                                                     offroad3                                                                                                                              Need More High Speed Steering?
• Front Toe – More toe-in gives you more steering coming out of the corners
• Front Caster – Less caster gives you more steering exiting corners
• Rear Ride Height – Raise rear ride height for more high speed steering                                                            offroad4                                                                                                                    More Stable Over Rough Tracks?
• Anti-squat – Less anti-squat allows better acceleration on rough tracks
• Rear Camber – More negative camber is more stable on bumpy tracks
• Rear Camber Link – Shorter camber links is more stable on bumpy tracks
• Front Shock Mounting – Move lower shock mount inside for bumpy tracks
• Battery Mounting – Place in the middle for most stable on all tracks                                                                 offroad5                                                                                                                   Credits: rcracingusa.net  http://     

RC Boating Basics

       While RC airplanes and cars tend to get the majority of modelers’ attention, there is another area of RC that can be just as much, if not even more fun than both. RC boats provide a totally different experience than flying a plane or driving a car on many different levels. There are boats for everyone from performance enthusiasts, casual sailing fans, those who love the detailed runabouts of years gone by and more. Besides the aesthetics of individual boats, there are other considerations to think about such as battery or fuel power, to build or buy a Ready-To-Run boat and more.

Hull Styles:
When talking about the performance and handling of a particular boat, the configuration of the hull will have enormous impact on the overall performance and handling of a boat on the water. When talking about the different types of hulls there are several different configurations commonly used in RC boats that we’re going to discuss. They are, in no particular order Deep-Vs, catamarans, sailboats and Minis.boat14        Deep-Vs are one of the most popular hull style for boats and are capable of tremendously high speeds. A Deep-V gets its name after the look and profile of the hull’s distinctive V-shape. This hull configuration relies on hull strakes for improved stability and cornering ability, and its Deep-V design helps the boat absorb the impact of bigger waves on rough water. In addition, the V-shape causes the boat to bank in the turns to assist turning. When you jump on the throttle with a Deep-V, the nose will typically come out of the water and as the boat gets on plane, it will ride on the rear 1/3 of the hull. boat15       Catamarans have been modeled after off-shore race boats and, due to their wider hull footprint acting as 2 sponsons, provide additional positive stability when compared to a Deep-V. The additional hull surface in the water provides the handling improvements and increased stability. While it is more stable, the fact that a catamaran has more of its hull in the water translates into increased drag and slightly reduced top speed.  boat16       For the best in relaxation, sailboats offer the lowest maintenance and are very fulfilling in regards to boat-handling skills. With no power other than the wind, skills must be honed to learn how to adjust the sails to take best advantage of wind currents. There is nothing like tacking into the wind, seemingly defying the wind direction.                                                            boat17       When you want to drive a boat but you don’t have access to a huge piece of open water, a mini boat is the perfect option. Minis are smaller than other boats, but they feature similar handling and performance characteristics of their larger cousins. Minis are available as RTRs that require very little preparation time to get on the water and provide an inexpensive and economical way for someone to get their feet wet in the world of RC boating. Some mini boats can even be driven in swimming pools if you need to get your boating fix in a snap.                                                          boat18       While fuel-powered boats used to rule the roost recent advancements in motor and battery technology has swung the pendulum in favor of electric boats. Electric boats also provide simple, plug-and-play operation. When you want to drive your boat, all you need to do is charge up the battery pack, plug it in, and you’re ready to go. There are two different electric power types that a boat can use, brushed or brushless. Brushed motor systems provide a good place for people to get their feet wet in RC boating, so-to-speak, without breaking the bank. Brushed motor systems are a little slower and less expensive but still provide decent power and runtimes. Brushless motor systems provide more power, requires less maintenance than brushed motors and can handle a higher voltage level. With brushless motor systems you’ll see an increase in acceleration and top speed while also being more efficient than their brushed counterparts. With some brushless motor systems they can handle over 22-volts! Now that’s some serious power!                                                            boat19       Gasoline-powered boats use basically the same gasoline that your full-size car uses, making refueling relatively inexpensive and easy. There is one difference between what your car runs on and what an RC boat utilizes for fuel. RC boats run off of a gasoline and oil mixture, very similar to what you might use in a gas leaf blower or string trimmer. Boats that run off of gasoline engines are larger and use a larger displacement engine than their nitro-powered cousins. Regardless of whether you decide to go with a nitro- or gasoline-powered boat, you will find that, generally speaking, fuel-powered boats offer extended run times when compared to battery-powered boats. Fuel-powered boats also offer the intangible sensation of the realistic sound produced by the engine as it rips across the water’s surface, adding to the experience and excitement. The engine noise could possibly eliminate some ponds and streams from consideration as areas to drive in.                              boat20       Much like the advancements to the power systems we’ve seen some solid improvements in the realm of RC transmitters and receivers. 27Mhz and 75Mhz radio systems have, for the most part, been replaced with 2.4GHz systems. With 2.4GHz systems you will be less prone to interference from other sources and you don’t need to worry about frequency conflicts like in years past. Spektrum’s 2.4GHz Marine Technology also adds in the extra safety of an integrated cut-off to prevent runaways.                                                                                                                                              boat21       As with all mechanical devices, inevitably some maintenance or repairs must occur. There are several key tools that you should have on hand at all times in case you need to perform basic maintenance, repairs and tuning. Whether it’s a kit, ARR, or RTR, there should be a small plastic baggie that includes a basic assortment of tools and Allen wrenches. These tools tend to work for a while, but the metal they’re made out of is relatively soft. After several uses, the heads of the wrenches can round off, making getting a good bite on a screw head a real pain. Invest in a good hobby-grade set of Allen wrenches and nut drivers. You’ll realize their value the first time you use them. Dynamite carries a wide variety of hand tools to make these jobs go as smoothly as possible. These sets come in the most popular sizes used in RC and are as durable as they are affordable. From Allen wrenches and nut drivers to glow drivers and accessories, Dynamite has the right tools for the job. Other key tools for your box should include things such as a tuning screwdriver for making needle adjustments on your engine, needle-nose pliers, fuel bottle, glow igniter (also known as a glow driver) and extra glow plugs.                                                                                                                                                                               boat22       Both electric and nitro boats can make use of a battery charger. Obviously electrics will need to have their main batteries charged, but rechargeable batteries are used in nitro boats too. From the batteries for hand-held starters to receiver packs, having a good charger can make it easier to run your boat. Timer chargers will save you money, but don’t provide quite as complete of a charge. Peak detection chargers cost a little more but feature circuitry to ensure your battery pack is brought to a complete charge safely.
If you are planning on purchasing an electric-powered boat, some RTRs may require you to purchase a battery pack and a battery charger. You may even need to purchase these items for a nitro boat as well, especially if your nitro boat includes some sort of electric or hand starter. There are several things to consider when purchasing a battery pack. One of the biggest things to consider is the type of battery you will use, be it LiPo or NiMH. NiMH batteries are less expensive and provide solid performance. NiMH packs do tend to have a sharper discharge curve, meaning the speed and performance difference between the start and end of a run tends to be greater. You also have performance declines from one run to another in a day commonly. Another option would be to go with LiPo battery packs. LiPo batteries are lighter weight than NiMH packs and have a flatter discharge curve, meaning the performance from start to finish is more consistent. LiPo batteries also don’t have performance degradation issues like NiMH packs have.
Another consideration with LiPo battery packs is what is called the “C” rating. The C-rating of a battery refers to the amperage discharge capability of a particular battery. The higher the C-rating of a pack the more load it can handle without issue. You can always go with a higher C-rated battery for a boat but you never want to go with a lower C-Rating. For most boats a 30C rating or higher is sufficient.
Finally you’ll want to consider the capacity of your battery. Capacity refers to the amount of run time per charge each type of pack is capable of. A higher milliamp rating, or mAh, will translate into a long time between charges. For example a 3300mAh battery would run out of power before a 4200mAh battery pack. You can adjust the capacity up or down without issue, the only difference would be how long the battery runs before it needs to be recharged.                                                                                            Credits: proboatmodels.com and 

6/7/2012 by

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Water Drop Effect — Proline How to Paint series

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