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= Generic Hang Glider =
= for FlightGear with LaRCsim and the UIUC Aeromodel =
= =
= Flight model by: =
= Michael Selig, et al. (m-selig@uiuc.edu) =
= http://www.aae.uiuc.edu/m-selig/apasim.html =
= =
= External model by: =
= Captain Slug (captainslg@aol.com) =
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To run, try:
fgfs --aircraft=airwaveXtreme150-v1-nl-uiuc
Files and directory structure required in $FG_ROOT/Aircraft/ to fly the
model:
airwaveXtreme150-v1-nl-uiuc-set.xml
airwaveXtreme150/Sounds/uiuc/airwaveXtreme150-sound.xml
UIUC/airwaveXtreme150-v1-nl/aircraft.dat
UIUC/airwaveXtreme150-v1-nl/CDfade.dat
UIUC/airwaveXtreme150-v1-nl/CLfade.dat
UIUC/airwaveXtreme150-v1-nl/Cmfade.dat
UIUC/airwaveXtreme150-v1-nl/README.airwaveXtreme150.html
airwaveXtreme150/Models/uiuc/hgldr-cs/hgldr_cs.0af
airwaveXtreme150/Models/uiuc/hgldr-cs/hgldr_cs.1af
airwaveXtreme150/Models/uiuc/hgldr-cs/hgldr_cs.mdl
airwaveXtreme150/Models/uiuc/hgldr-cs/hgldr-cs-model.xml
These files above come with the FlightGear base package.
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Model description and updates:
11/8/2002 - External model files added.
* Permission granted to use and release these with FlightGear under
the GNU GPL. Thanks go to Captain Slug (captainslg@aol.com)!
5/25/2002 - First release: v1-nl
* Despite its namesake, this is not intended to be a model of the
Airwave Xtreme hang glider. However, this hang glider has relatively
high performance with a max L/D of approximately 12, which is in
line with the Airwave Xtreme 150.
* Lift, drag and pitching moment is modeled from -180 to +180 deg.
* In longitudinal flight, moving the control bar fore and aft does two
things simultaneously. It changes the c.g. of the hang glider as well
as the angle of attack of the wing. This changes the lift, drag and
moment about the c.g. These effects are properly modeled. The
c.g. shift is not modeled for lateral directional flight, however.
Instead a typical aileron is modeled for roll control. Thus joystick
position controls the fore/aft c.g. for pitch and "aileron" deflection
for roll.
* Apparent mass effects are modeled, and this together w/ the c.g. shift
both produce the characteristics hang glider landing dynamics -- big
flares.
* Full aft c.g. (aft joystick) will put the hang glider in a vertical
stable descent. On average, the pitching moment characteristics of a
hang glider lead to stable flight at near 90 deg angle of attack
(vertical descent). In real life unsteady vortex shedding would
prevent stable flight in this regime. This unsteadiness might be
modeled in later versions.
* The aerodynamics are modeled after experimental data taken by
Ormiston, R.A., "Wing Tunnel Tests of Four Flexible Wing Ultralight
Gliders," NASA CP 2085, Part II, March 1979, pp 557-589. These
gliders are "vintage" hang gliders with more or less poor performance
relative to modern hang gliders. To better model current day hang
gliders, some adjustments were made to the pitching moment and drag
polar. With the adjustment to the drag polar, the maximum L/D is now
approximate 12. Pitching moment data is discussed more below.
* Because a hang glider controls pitch with c.g. shift, the pitching
moment curves are anything but linear. This produces interesting
aerodynamic control effects. Most notably, at low speeds, it is
relatively easy to pitch up the glider; whereas, at high speeds, the
pitch up is slower. Low speeds are experienced during landing, in
particular the exaggerated flare. High speeds can be had in a
vertical dive. Some adjustments were made to the experimental
pitching moment data to more closely model the better handling of
current hang gliders. (If I can find a 3D model of an older
lower-performance hang glider (1970 vintage), I will put back in the
scary characteristics that led to many early hang glider accidents.)
* The hang glider simulation starts on the ground, and in real life
there is no engine. Because this is not real life, one of two things
can be done to reach altitude. Ctrl-U can be used to jump up in
1000-ft increments. Alternatively, an engine is included; add
throttle and the hang glider will climb.
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**************************************************
Prof. Michael S. Selig
Dept. of Aerospace Engineering
University of Illinois at Urbana-Champaign
306 Talbot Laboratory
104 South Wright Street
Urbana, IL 61801-2935
(217) 244-5757 (o), (509) 691-1373 (fax)
m-selig@uiuc.edu
http://www.aae.uiuc.edu/m-selig
**************************************************