Hi all, (I'm new to this list, my apologies if this is the wrong forum for my questions.)
I am a paraglider pilot who have been toying with the idea of modelling a paraglider in a flight simulator. I made a model in X-Plane first, but had to give up because X-Plane was too limited to be able to model the controls of a paraglider. (And because my model preferred spinning wildly out of control to actual flying...) I hope that the project can be done in FlightGear. At least it seams so, based on what I've read in the FAQs and docs. I have decent C++ programming experience, but only rudimentary 3D graphics knowledge. Just so that we are all clear on the subject: A lot of people confuse paragliders, parachutes and hanggliders. This is a paraglider (large image): http://mail.egroup.no/HLSK/Galleriet.nsf/0/E13D5199716A1920C1256BD6004D5F15/$FILE/EPSN0072.jpg In text, a paraglider is a ram-air inflated, flexible fabric wing, differing from a hangglider in that it has no spars, and from a square parachute in its higher aspect ratio and better glide angle. The pilot hangs suspended below the wing. It can be a glider or powered by a light engine. Do you think it can be done? Some challenges / more information: Take off and landing is usually done by foot, but a trike can be used (must be used for the simulation). Pendulum effect: The pilot, who weighs 10-18 times as much as the wing, is situated 8 meters below the wing. This means that the center of gravity is about 7 meters below the center of lift. Result: Extreme stability. You can let go of the controls in almost any situation, and the wing will soon fly straight. However, the pendulum effect can be used for various acrobatic manouvers: wing-overs, spiral dive, flat spin, SAT, etc., even loops. (The wing can never dive in a straight line, though.) If flightgear has a "real" physics engine, then this should be possible to simulate. Making a turn is radically different from a normal plane: A turn to the left is done by pulling down the trailing edge on the left side of the wing. This increases the lift on the left side, which first causes a roll to the right. However, the increased lift gives more drag, which causes a yaw force to the left, and as the wing turns the pendulum effect then causes a roll to the left. Weight shift is also used for turning. This counteracts the "wrong" roll at the beginning of a turn. The wing can be steered by weight shift alone, but the turn rate is less. Speed controll: To brake, pull down both sides of the wing equal amounts, thus increasing AOA. To speed up, there is a pulley system that pitches the wing profile down, decreasing AOA. Glide ratio control: To get a steeper glide, the wing tips can be folded backwards, which reduces wing area and aspect ratio. (This should be possible with flightgear too, I guess, by a little programming.) Other controlled wing deformations are also possible. Collapses: A paraglider will collapse if negative AOA occurs. This will be the most difficult property to model, I think. Collapses can be symmetric or assymetric, and of various sizes. A good simulation of collapse and recovery will be next to impossible, but it should be possible to do some crude approximations. Extreme terrain detail: To give a reasonably good flight experince the terrain detail must be a lot higher than in normal flight sims. Paragliders fly low and slow. Terrain resolution down to 1 meter, with textures down to maybe 10 pixels/meter, would be great. Also, trees would improve the feel a lot. This would of course require that only the closest terrain is modeled at this accuracy, and the areas that are further away use progressively less detail. Thermals and rigde lift for soaring would be great, is this supported? Some standard glider specs, for whom it may concern: Weight: 6 kg (wing) 10-15 kg (harness) 70-130 kg (with pilot) Speed: 20-50 (60) km/h Min. sink rate: 1 m/s (continous, can be 0 when flaring) Max. sink rate (in spiral dive): 20 m/s Best glide ratio: 7-9 Flat area: 25-35 sqm Flat wingspan: 11-13 m Flat aspect ratio: 4.5-6.5 Projected wingspan: 9-10 m Some other questions: Which FDM should I use? I'm thinking YASim but I'm not sure. Is the 3D-model mini-howto from 2002 still up to date? http://www.flightgear.org/Docs/fgfs-model-howto.html best regards, -- Gunnstein Lye Systems engineer [EMAIL PROTECTED] | eZ systems | ez.no _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
