Tagged: RC Airplane Batteries

F4U-1D Corsair 60cc ARF 85.5″

Designed to operate from aircraft carriers and/or land-based facilities, the F4U-1D Corsair was a force to be reckoned with to the Japanese during WWII. With its gull wing design, impressive looks and power, the Corsair was one of the most recognizable WWII aircraft.                                                                                                            The Hangar 9® F4U-1D Corsair is a giant-scale masterpiece for 60cc power plants that delivers scale details worthy of being called competition grade. Its scale outline, impressive scale appearance, and Hangar 9 performance, make this an exciting warbird to show off at the field. The construction is primarily wood with fully balsa-sheeted areas, but the outer wing panels and control surfaces (except the three-panel flaps) feature exposed ribs like was done with the full-scale fighter.                                                                                                                                            The three-piece wing features a robust fiberglass structure in the center which houses the custom main retracts built by Robart Mfg. (sold separately). A retractable tail wheel option is available from Hangar 9 as well as aluminum spoke wheels that set off this amazing model in an inspirational way.                                                                                                                                                                       Out of the box, it comes finished in genuine UltraCote® covering, fiberglass cowling and wing center section that are painted to match. You also get scale details like a full depth cockpit, hidden tail and flap control linkages, scale rib detail, scale 3-panel flaps, dummy radial engine, sliding canopy and so much more. Optional scale accessories include scale tail wheel, main wheels and retracts that operate with pneumatic or electric mechanisms, droppable bombs or fuel tanks, scale 3-blade display prop and optional navigation lights.                                                                                                                                                                                                A wide range of choices are available for power; there’s the ease and economy of a 50–60cc two-stroke gas engine, sound and torque of a twin-cylinder 57cc four-stroke, or the realism of an Evolution 777 four-stroke radial. The hardware package included is very high-quality and complete as possible no matter power system you favor so you can get to flying this magnificent warbird quickly.                                                                                                                                                   Few World War II fighters inspired awe in both friend and foe like the F4U-1A Corsair. This impressive scale giant offers top gun scale looks, while delivering the Hangar 9 design reputation for superior flying performance.    

 

Product description

Key Features

5 CH BlitzRCWorks VTOL V-22 Osprey RC Warbird Airplane

  Boeing is apparently working on a large passenger aircraft with vertical takeoff and landing features. The company received a patent for a tilt-rotor design that has room for at least 100 passengers, according to a Business Insider report Thursday. The VTOL plane has potential for both civilian and military use, according to the report. It seems to be inspired in part by the famous two-engine V-22 Osprey, which Boeing and Bell Helicopters developed for the U.S. military in the 1980s, the first of its kind designed for use by the Marines and Air Force. The patent for the unnamed aircraft includes potential uses for commercial flights, military missions or personal transport, according to the report. Its design includes four engines mounted on two fixed wings along with two large rotors attached on the tips for vertical takeoffs and landings.

The company hasn’t revealed details of its intentions for the VTOL design, but a civilian passenger plane with such capabilities will likely raise speculation about the potential for off-airport commercial transportation. “Boeing files tons of patents so this might not even come to fruition,” a Boeing spokesman told Business Insider. “I’m not saying it won’t.” The patented design also calls for lower wings on the airframe compared to the V-22 to allow for passenger exits as well as simpler maintenance, a Seattle Times report notes.                                                                                                                    

                                                                                                                                                       Do you know what VTOL means? Aside from vertical takeoff and landing, it means taking off and landing can be done in a multitude of different terrains. No runway necessary. This model was in the making for about 3 years, with countless hours of development and testing. There were a lot of hurdles in the way, but it’s finally here.                                                                               A market-first, and ground-breaking scale V-22 Osprey with full VTOL and forward flight capabilities. This beauty is built with a high-precision stabilization board, quality electronics, and of course, EPO foam. With its 3-point propulsion system, it manages to fly with unrivaled stability. Plus, the transition to forward flight seamlessly blends with the overall flying experience, making it easier on the pilot.                                                                           Currently there’s nothing like it in the scale and performance department, making this a one of a kind model. Did we mention, no runway necessary? Take it for a spin today!                                                                                                            

Feature:
  • 5 operable channels (aileron, elevator, throttle, rudder and forward flight actuation)

  • Professional high-precision stabilization board

  • 3-point propulsion system for stability

  • Simple and easy to assemble

  • Built with high-grade EPO foam

  • Reliable dual 17g metal-gear servo system for forward flight actuation

  • Detachable main wings for ease of transportation

  • Spacious battery compartment for a variety of battery options

  • Scale appearance

  • High-performance propulsion system

  • Stable forward flight transition

Credits: https://www.avweb.com/  By Elaine Kauh | October 27, 2016     http://

FMS F4U Corsair RC Airplane 6CH 1700mm (66.9″) Wingspan Blue with Flaps LED Retracts PNP Warbird

The FMS Corsair airframe features a removable 2 piece wing that is simplistic in attachment and connection, the new FMS ‘multi-pin plugs’ mean that the complex wiring is now just a single connection per wing and not the usual plate full of spaghetti normally seen in lesser airframes.                                                                       The large cockpit is adorned with the full complement of dials and levers and the hand painted pilot finishes the effect. The chrome spinner and reinforced nylon four blade propeller really does give a purposeful look and assist in giving rise to the knick name of the ‘whistling death’.                                                                                           As you would expect, the huge brushless out- runner motor is mated with a top quality ESC enabling stunning flight performance.                                                                                                     New metal gear servos handle all the control surfaces and are fast with great centering performance. The resulting flight performance gives a finesse unseen in a model in this class. Order the 1700 Series F4U Corsair today and steal the limelight at your airfield.                                                                  

Manufacturer FMS
Wingspan 1700mm/66.9in
Overall Length 1,480mm/52.2in
Flying Weight Around 4,700g
Motor Size Brushless 5060-KV300
ESC 85A with 8A SBEC
Servo 3 x 9g analog,5 x 17g metal digital,5 x 25g metal
Radio 6 Channel
CG (center of gravity) 90mm (From Leading Edge)
Prop Size 17*10
Recommended Battery Li-Po 22.2V 3300-4000mAh 25C
Aileron Yes
Elevator Yes
Rudder Yes
Flaps Yes
Retracts Yes
Approx. Flying Duration 6 minutes
Minimum Age Recommendation 14+
Experience Level Intermediate
Recommended Environment Outdoor
Assembly Time 1.5 hours
Is Assembly Required Yes
Material Durable EPO
Package Options PNP
Requires PNP Requires Radio System, Battery and Charger

Flyzone DHC-2 Beaver Select Ready to Fly Aircraft

The original DHC-2 Beaver is one of the most widely used bush planes in the world. The original model by Flyzone is one of the most popular and sought after remote controlled aircraft on the market. Now, experience the ease and versatility of the original Beaver in the Island Wings Beaver with a sleek trim scheme modeled on a real Alaskan bush plane!                                                                                           “Lady Esther” – the full-scale de Havilland Beaver that inspired this model – is piloted by self-described “flight junkie” Michelle Masden. Owner of Island Wings Air Service®, Masden uses the aircraft to take visitors on sightseeing tours of the Alaskan wilds. Learn more about Masden and the Lady Esther at islandwings.com!

    • conventional landing gear and floats with water rudders

    • working navigation and landing lights

    • no-glue assembly

 

  • brushless outrunner motor and 40A ESC                                                                                                                      Includes floats for water takeoffs and landings. And big, tundra-style tires on the conventional gear.                                                                                                                                                                                          A hatch on the bottom of the fuselage provides easy access to the battery compartment.

    Battery shown not included                                                                                                                                                                                                Working navigation and landing lights add exceptional realism.                                                                                                                  

    The ailerons and flaps feature drop hinges and authentic corrugation.

     The new DHC-2 is as fun and easy to fly as the original! It includes an authentic new trim scheme, larger bush tires on the conventional landing gear and, of course, floats with water rudders. “Lady Esther” — the full-scale de Havilland Beaver that inspired this model — is piloted by self-described “flight junkie” Michelle Masden. Owner of Island Wings Air Service® , Masden uses the aircraft to take visitors on sightseeing tours of the Alaskan wilds. Learn more about Masden and the Lady Esther at islandwings.com! FLZA4024 Wingspan: 59.5 in (1510 mm) Length: 38.5 in (980 mm) Weight: 48-52 oz (1360-1470 g) Requires: 5+ channel transmitter & receiver, 11.1V 1800mAh LiPo battery & LiPo charger Includes: Conventional landing gear and floats with water rudders, working navigation and landing lights, no-glue assembly, brushless outrunner motor and 40A ESC.                                                                   http://

                                                                                         

Upgraded HSD Gray Fighting Falcon 7CH F-16 F16 105mm 12S 150A RC EDF Jet

PAYA LEBAR AIR BASE, Singapore — An F-16 Fighting Falcon from the 36th Fighter Squadron at Osan Air Base, South Korea, lands here after a mission during Commando Sling 04-3. U.S. and Singaporean Airmen trained together using realistic dissimilar aircraft air-to-air combat tactics. (U.S. Air Force photo by Master Sgt. Val Gempis)                                                                                                                                                                                     Mission
The F-16 Fighting Falcon is a compact, multi-role fighter aircraft. It is highly maneuverable and has proven itself in air-to-air combat and air-to-surface attack. It provides a relatively low-cost, high-performance weapon system for the United States and allied nations.

Features
In an air combat role, the F-16’s maneuverability and combat radius (distance it can fly to enter air combat, stay, fight and return) exceed that of all potential threat fighter aircraft. It can locate targets in all weather conditions and detect low flying aircraft in radar ground clutter. In an air-to-surface role, the F-16 can fly more than 500 miles (860 kilometers), deliver its weapons with superior accuracy, defend itself against enemy aircraft, and return to its starting point. An all-weather capability allows it to accurately deliver ordnance during non-visual bombing conditions.

In designing the F-16, advanced aerospace science and proven reliable systems from other aircraft such as the F-15 and F-111 were selected. These were combined to simplify the airplane and reduce its size, purchase price, maintenance costs and weight. The light weight of the fuselage is achieved without reducing its strength. With a full load of internal fuel, the F-16 can withstand up to nine G’s — nine times the force of gravity — which exceeds the capability of other current fighter aircraft.

The cockpit and its bubble canopy give the pilot unobstructed forward and upward vision, and greatly improved vision over the side and to the rear. The seat-back angle was expanded from the usual 13 degrees to 30 degrees, increasing pilot comfort and gravity force tolerance. The pilot has excellent flight control of the F-16 through its “fly-by-wire” system. Electrical wires relay commands, replacing the usual cables and linkage controls. For easy and accurate control of the aircraft during high G-force combat maneuvers, a side stick controller is used instead of the conventional center-mounted stick. Hand pressure on the side stick controller sends electrical signals to actuators of flight control surfaces such as ailerons and rudder.

Avionics systems include a highly accurate enhanced global positioning and inertial navigation systems, or EGI, in which computers provide steering information to the pilot. The plane has UHF and VHF radios plus an instrument landing system. It also has a warning system and modular countermeasure pods to be used against airborne or surface electronic threats. The fuselage has space for additional avionics systems.

Background
The F-16A, a single-seat model, first flew in December 1976. The first operational F-16A was delivered in January 1979 to the 388th Tactical Fighter Wing at Hill Air Force Base, Utah.

The F-16B, a two-seat model, has tandem cockpits that are about the same size as the one in the A model. Its bubble canopy extends to cover the second cockpit. To make room for the second cockpit, the forward fuselage fuel tank and avionics growth space were reduced. During training, the forward cockpit is used by a student pilot with an instructor pilot in the rear cockpit.

All F-16s delivered since November 1981 have built-in structural and wiring provisions and systems architecture that permit expansion of the multirole flexibility to perform precision strike, night attack and beyond-visual-range interception missions. This improvement program led to the F-16C and F-16D aircraft, which are the single- and two-place counterparts to the F-16A/B, and incorporate the latest cockpit control and display technology. All active units and many Air National Guard and Air Force Reserve units have converted to the F-16C/D.

The F-16 was built under an unusual agreement creating a consortium between the United States and four NATO countries: Belgium, Denmark, the Netherlands and Norway. These countries jointly produced with the United States an initial 348 F-16s for their air forces. Final airframe assembly lines were located in Belgium and the Netherlands. The consortium’s F-16s are assembled from components manufactured in all five countries. Belgium also provides final assembly of the F100 engine used in the European F-16s. Recently, Portugal joined the consortium. The long-term benefits of this program will be technology transfer among the nations producing the F-16, and a common-use aircraft for NATO nations. This program increases the supply and availability of repair parts in Europe and improves the F-16’s combat readiness.

U.S. Air Force F-16 multirole fighters were deployed to the Persian Gulf in 1991 in support of Operation Desert Storm, where more sorties were flown than with any other aircraft. These fighters were used to attack airfields, military production facilities, Scud missiles sites and a variety of other targets.

During Operation Allied Force, U.S. Air Force F-16 multirole fighters flew a variety of missions to include suppression of enemy air defense, offensive counter air, defensive counter air, close air support and forward air controller missions. Mission results were outstanding as these fighters destroyed radar sites, vehicles, tanks, MiGs and buildings.

Since Sept. 11, 2001, the F-16 has been a major component of the combat forces committed to the war on terrorism flying thousands of sorties in support of operations Noble Eagle (Homeland Defense), Enduring Freedom in Afghanistan and Iraqi Freedom

General characteristics
Primary function: multirole fighter
Contractor: Lockheed Martin Corp.
Power plant: F-16C/D: one Pratt and Whitney F100-PW-200/220/229 or General Electric F110-GE-100/129
Thrust: F-16C/D, 27,000 pounds
Wingspan: 32 feet, 8 inches (9.8 meters)
Length: 49 feet, 5 inches (14.8 meters)
Height: 16 feet (4.8 meters)
Weight: 19,700 pounds without fuel (8,936 kilograms)
Maximum takeoff weight: 37,500 pounds (16,875 kilograms)
Fuel capacity: 7,000 pounds internal (3,175 kilograms); typical capacity, 12,000 pounds with two external tanks (5443 kilograms)
Payload: two 2,000-pound bombs, two AIM-9, two AIM-120 and two 2400-pound external fuel tanks
Speed: 1,500 mph (Mach 2 at altitude)
Range: more than 2,002 miles ferry range (1,740 nautical miles)
Ceiling: above 50,000 feet (15 kilometers)
Armament: one M-61A1 20mm multibarrel cannon with 500 rounds; external stations can carry up to six air-to-air missiles, conventional air-to-air and air-to-surface munitions and electronic countermeasure pods
Crew: F-16C, one; F-16D, one or two
Unit cost: F-16A/B , $14.6 million (fiscal 98 constant dollars); F-16C/D,$18.8 million (fiscal 98 constant dollars)
Initial operating capability: F-16A, January 1979; F-16C/D Block 25-32, 1981;  F-16C/D Block 40-42, 1989; and F-16C/D Block 50-52, 1994
Inventory: total force, F-16C/D, 1017                                                                                                                             Credits:http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104505/f-16-fighting-falcon.aspx           RLRC Toys   

Beginner RC Planes – What Makes the Best Beginner RC Plane

What Makes the Best Beginner RC Plane                                                                                                       When getting started in rc flying you’re going to have to make the decision of what’s going to be your very first plane. Being a beginner pilot you are going to want a beginner plane. Let’s take a look at some of the attributes that make a good beginner plane.                                                                                                   1. Electric powered. Electric powered planes are much cheaper and easier to use than gas powered. You turn them on and they are ready to go. Gas powered motors need a special fuel and then you have to tune them. It’s a lot more work. Also electric planes are much cheaper than gas powered. Most beginner electric planes come with everything you need to fly. For a gas powered plane you need to purchase everything separate.
plane23plane24                                                       2. Top Wing design. This is a plane that has the wing on top of the plane. Having the wing on top of the plane gives it more lift. Lift helps keep the plane floating in the air. As a beginner you are going to want a plane that floats by itself, especially if you run into trouble.
plane25                                                                                                              3. Large wingspan. A large wingspan will also add more lift to the plane.

plane26                                                                                                         4. 2 or 3 channels. 2-channel planes allow you to control the up/down and side to side (turning) movement of the plane. A 3-channel will allow you to do the same, but also allows you to control the speed of the motor. This allows you to control the pitch of the plane. A 4-channel plane is too much for a beginner. The 4th channel is used to control the ailerons which are used in more advanced flying.
plane27plane28plane29

5. Anti Crash Technology (ACT). This is not found in very many planes, but if you find one that uses it this technology is great. These planes use sensors to check the direction of the plane. If they sense that the plane is going into a dive they take over control of the plane and adjust its altitude giving you more time to react and avoid a crash.

Following these guidelines will help you find a great beginner rc plane, one that you will enjoy flying for a long time. Good luck and happy flying.

Josh Elkins is an avid rc plane fan and wants to help those who are interested in the hobby. You can find more information about beginner rc planes at www.squidoo.com/BeginnerRcPlanes

Article Source: http://EzineArticles.com/expert/Josh_Elkins/168881  http:// Shop Amazon – All-New Fire TV, Now with 4K

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.

aero2

  • 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.

aero3

  • 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.

aero4                                                                                                            

  • 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.

aero6

      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.

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

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  • 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.

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  • 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.

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  • 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).

aero20

  • 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:// 

Know the Different Battery Types for Electric RC Vehicles

Various RC vehicles run on different power sources. Among these, RC cars or boats that run on electricity are the easiest to operate. With electric remote control cars or boats, there is no need for sophisticated technical knowledge or the need for glow plugs or fuel.

The only requirements are to charge the batteries and to ensure correct wiring. That’s pretty much it!

Rechargeable battery packs for RC vehicles can be typically either one of the following: NiCd, NiMH, or Li-Po cells. Following are more information on RC batteries.

Know your batteries

Read more »