My experience in flying full scale sailplanes leads me to believe there will
be inertial lag problems in BOTH airspeed and variometer. In a dynamic
situation, like circling in a thermal with gusts and varying bank angles,
chasing airspeed with pitot pressure and altitude pressure sensing would be
akin to chasing your tail. In a full scale, attempting to fly by watching
the airspeed and vario will cause you to be in out-of-control in pitch in
just a few seconds. A full scale sailplane pilot makes the short term pitch
attitude adjustments by watching the horizon "automatically" in his
peripheral vision. Aircraft pitch attitude coarse adjustments are made with
"glances" at the ASI (air speed indicator) to check the general speed trend.
It is similar to driving a car on the highway. You don't stare at the
speedometer and adjust the gas pedal force, and a cruise control has a very
"soft" target speed point to avoid speed osscilations.
A solution used in full scale aircraft would be to track angle of attack
with a streaming vane, and couple with inputs from airspeed. Gusts would be
corrected for instantly, and the correct speed would be maintained
regardless of bank angle and ballasting/wing loading.
Maybe some techno-wizards will have more input on this subject of "stability
and control augumentation".
Dan deVries
DEVRIES DESIGN, Inc.
Product Design --+-- Patent/Litigation Graphics
_______
_____________ |_______________
0
[EMAIL PROTECTED]
>My single engine land flight instructors always told me to "control my
>airspeed with my elevator, and control my altitude with my throttle".
>
>For any aircraft, especially gliders, maintaining a constant airspeed is
>important in order to get the best performance. Sink can be minimized
>by maintaining the airspeed where lowest sink occurs. There is another
>airspeed for best glide ratio, and others apply when flaps are deployed,
>etc.
>
>I would like to know if anyone has any comments on the practicality of
>using an airspeed controller, like the one shown at
>http://members.aol.com/uavnav/pdc25.html , to optimize glider
>performance.
>This would allow the pilot to dial in an airspeed and then simply steer
>the glider so long as he is in smooth air. He could get by with a more
>rearward CG, which would lead to better performance also.
>
>If he is also using a vario, there would be no error due to conversion
>of altitude (potential energy) into airspeed (kinetic energy), since
>airspeed would be constant.
>
>What do you think? Is it worth a try?
>
>Thanks,
>
>Jimmy
>RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
>
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
