A hangmotor is a powered hang glider harness with a motor and propeller attached. An ordinary hang glider is used for the wing and the pilot can foot-launch from flat ground, needing an area of about the size of a football field to get airborne (less if there's oncoming breeze). It is also called a "powered harness" or FLPHG (foot-launched powered hang glider).
The first commercially available foot-launched powered hang glider harness, The Mosquito, was designed and produced commercially by Swedish inventor Johan Åhling. Johan’s first commercial powered harness flew in 1987, but it had only 10 horsepower and a few bugs had to be worked out. Its appeal grew first amongst European and Australian hang glider pilots, and recently it has started to become popular in North America. The improved Mosquito design is now called NRG, and various similar designs are now being produced by other manufacturers, with names such as: DoodleBug, Raven, Wasp, X1, Booster and Explorer.
Configurations
Current powered harnesses weigh 50 to 70 pounds (22-32 Kg) without a parachute, and fold neatly into a 5-foot long harness bag with a handle that allows it to be carried like luggage. Currently, there are two harness configurations: prone (face down) and supine (sitting). Both configurations allow the pilot to take-off and land on his/her feet.
Training
It is essential that a new powered harness pilot first take lessons in an unpowered glider at a certified school and achieve at least 30 to 50 hours of solo flight time before transitioning to a foot-launched powered harness. Basic aerodynamics, safety, meteorology, local regulations and procedures must also be learned during training.
Flying
Foot-launched powered harnesses (hangmotor) have limited power and thrust and are best used to achieve enough height to find a rising air thermal and soar. The hilights below are not meant to replace a comprehensive certified training course but to give the prospective powered HG pilot an idea of the skill development required and of the general control input.
* Launch - A successful take off with a powered harness depends mostly on precise control of the nose angle, especially in calm winds or at altitudes above sea level. Too low and the glider will simply not fly. If it is too high it will create excessive drag and will never get the speed it needs.
The pilot remains upright throughout the run, allowing forward acceleration to be provided by the push of the engine. The pilot does not use his legs to accelerate but only to carry the weight of himself and the glider. Acceleration is smooth with a light touch on the control bar, allowing the glider to fly itself at its trim position. The pilot runs as long as necessary, taking strides of ever increasing length (“moon walking”), During the last steps most of the pilot’s weight will be carried by the glider. There must be no noticeable change in pitch angle, and the pilot will have stopped running only after the last steps no longer touch the ground.
During the take off run, the harness' thrust must be transmitted to the glider through the hang strap and not through the pilot's hands to the control frame. By the time the glider comes off the pilot's shoulders, he must immediately pull in more and move forward through the control frame so that the hang loop becomes tight and is angled slightly forward so that the harness is pulling the glider forward by the hang strap. Because the thrust force enters the glider right at the CG, it now only requires of a light touch to control the pitch. Allow the glider to find its own pitch angle, and fly it on ground effect as long as possible - The glider will climb on its own once it has the speed to do so. Whatever you do, do not push out.
* Turns - Even very experienced hang glider pilots will need to learn some new tricks when it comes to turning under power. Most pilots were taught to 'lead with our feet' in making turns. This is effective for un-powered flight, but adding weight and thrust to our feet changes things. Yawing our bodies also changes the thrust line and helps engage a turn. Some pilots find it better to keep their body (and thrust line) parallel with the keel; Some pilots use a combination of both weight-shift and thrust line to turn effortlesly while under power.
The DoodleBug is a supine unit that uses the limit lines to keep the prop relatively stationary. As the pilot moves to one side, this arrangement moves the thrust line so that it actually opposes the turn direction. It is evident that this setup is beneficial in helping to create a more stable turn. Some pilots flying prone configuration units like the freedom of being able to control the direction of thrust as it gives them another way to fine tune a turn.
Once the glider gains a comfortable altitude the pilot may choose to reduce the throttle for easier control, especially in turns. Zipping up the harness also retract the rear skids, which are then clipped into clamps on the side of the harness. If the pilot finds lift he may wish to shut off the engine and soar normally but it will take some time getting used to the extra weight behind the feet.
* Landing - Landings are easy - wait till you feel the harness legs dragging, wait a half second, and flare mildly. Your forward position and extra mass give you more flare authority than you are used to. But the mass of the motor still wants to continue forward - expect a feeling like a nudge from behind after you have landed, and be prepared to take a step or two.
Construction
Getting into the harness requires passing both legs through padded straps and wearing the harness like a vest, with a zipper and/or clips at the front. Powered foot-launched hang glider harnesses are built around a light metal frame with the engine mounted on the rear.
Most powered harnesses in production are equipped with the light weight Radne Raket two stroke 120cc engine, producing l4hp at 8800 RPM and a 1:3.5 reduction drive. Pilots living and operating at higher than 5000 feet altitude, an 18hp harness is recommended. The motor is supported on the ground by two retractable landing gear tubes with skids, making for no extra weight for the pilot to carry, apart from the 4 litre aerodynamic gasoline tank attached to the top of the control bar frame. Flight autonomy with one gallon of fuel depends on throttle settings, but it ranges between 60 and 90 minutes of continuous engine use.
Getting into the harness requires passing both legs through padded straps and wearing the harness like a vest, with a zipper and/or clips at the front.
The throttle is activated during take-off by means of a mouth-throttle; in order to have both hands free for proper weight-shift control. Once airborne, a foot throttle, thumb throttle or cruise control can be used.
A folding propeller is often preferred by pilots who enjoy optimum soaring with the engine off on rising air thermals. The whole aircraft is easily maneuvered on the ground into takeoff position with the pilot buckled into the harness and ready to start the unit by themselves, either with a pull-start or electric starter.
External links
- Wind-drifter, technical details, links and articles.
- Mosquito America manufacturer
- DoodleBug manufacturer
- X1 manufacturer
- Wasp manufacturer
- Raven manufacturer
- US Hang gliding association