Radio-controlled glider
They are able to sustain continuous flight by exploiting the lift produced by slopes and thermals, controlled remotely from the ground with a transmitter.
They can be constructed from a variety of materials, including wood, plastic, polymer foams, and composites, and can vary in wing loading from very light to relatively heavy, depending on their intended use.
International radio-controlled glider competitions are regulated by the Fédération Aéronautique Internationale (FAI) although many countries have their own national classes.
Depending on craft design and the conditions at launch—the pilot or an assistant need only to gently 'throw' it into the wind, at an angle deemed best suited, usually between horizontal and 45 degrees of zenith.
In this method another person runs along the ground pulling a 50-to-150-metre (160 to 490 ft) line with the glider attached to the end, while the pilot steers it.
A variation of this is used in F3J competition when two tow men run with the pulley to generate much faster launches (although the models have to be sufficiently strong to handle the loads placed upon them by this method) which allows the model to use the energy to "zoom" (the model is pointed downwards briefly to convert the stored energy in the stretched monofilament line into airspeed, and once the airspeed exceeds the towline speed the line is released, before being rotated into a nose high attitude and the speed being converted back into additional height).
The running person is replaced by a combined length of elastic cord or rubber tubing and line which is attached to the ground upwind of the pilot, often using a 'corkscrew' dog stake.
Although this method is spectacular, it requires an experienced pilot to steer the carrier aircraft as the addition of the glider can significantly affect the handling of their model.
Although DLGs are a fairly new type of model glider, they are gaining popularity due to their ease of launching and efficient flight characteristics.
[3] A parachute is used (pulled shut by the launch tension) to assist in preventing the winch spool overrunning when the model is released.
The F3F is one of many competition categories for model and full scale aircraft that are defined by the Fédération Aéronautique Internationale (FAI).
There is also a wide appeal in owning an inexpensive glider that is also a stand-off scale model, particularly of favorite World War II fighters, e.g. the Spitfire/Seafire, P-51 Mustang and P-47 Thunderbolt.
Model EPP jet fighter slope soarers have become extremely popular, usually either 1950s and some 1960s designs e.g. the MiG-15, the P-80 Shooting Star, and the F-86 Sabre, and the Northrop F-5 and F-20.
Dynamic soaring is a relatively new style of flying model gliders whereby the windshear just downwind of certain slopes can be used to create high speeds.
These gliders typically using airfoils that allow identical upright and inverted performance, as well as unique fuselage shapes that permit some amount of sustained knife edge flight.
Most gliders feature three axes of control (aileron, elevator, and rudder), and often use flaperons to extend the capabilities of the airfoils for maximum aerobatic performance.
Some of the most advanced slope aerobatics gliders feature all-moving elevators and rudders capable of 180* rotation, allowing them to perform "flips" around the pitch or yaw axis, respectively.
Airframes are constructed of any material, with wood, fiberglass and/or carbon fiber being preferred for gliders intended for precision aerobatics, and EPP (expanded polypropylene) being popular for low altitude aerobatics where interactions with the ground - like wingtip and/or inverted fin drags, or touch-and-goes off of obstacles - are commonly performed and desired.
Thermal soaring gliders are normally launched with a bungee cord catapult, a winch or towed by a powered model aircraft.
This has produced a new term, "slermal", to describe the mixture of both slope lift and thermal activity coming up the hill face.
F3J is one of many competition categories for model and full scale aircraft that are defined by the Fédération Aéronautique Internationale (FAI).
The models have evolved into predominantly all composite gliders of 3.4–4 m wingspan with full span flaps and ailerons, sufficiently strong to take a two-man tow in a wind of up to 20 mph.
It must be flown very slowly to achieve the duration time and create high lift to maximize launch altitude off the winch.
Advances in composites and micro radio equipment have enabled these gliders to increase performance dramatically over their historical javelin style hand launched siblings.
Well-built gliders will typically survive head-on collisions with combined speeds exceeding 50 mph (80 km/h) with little to no damage to either plane.
This provides the glider with lower air resistance and reduces overall drag which would be present if the propeller was to remain in its open or natural state.
