all sailplanes

general handling
adverse yaw
spiral stability/yaw-roll couple
lift slope/stall
controls

specific sailplanes

schleicher ASW27
genesis 2
ventus B

I have flown quite a few high performance gliders and can tell you first hand that just about all of them are unstable.
...
I want to make it clear that the handling of a high performance glass Glider is very different to a wooden Glider used for training like the K13.

The adverse yaw IS strong and almost all glass gliders run out of rudder before ailerons are at full deflection, but this is speed dependant, adverse yaw is worse the nearer to the stall you get.

If you put in and hold full rudder then the glider will roll into a spiral dive, suprisingly quickly in some.

High aspect ratio wings (as Gliders have) have a steep lift slope, therefore the elevator is more sensitive, and the stall happens at quite a low AoA, 10-15 degrees.

One last point, Gliders fitted with flaps, the flaps are raised above the TE for high speed flight and lowed below the TE for slow flight/landing, (not including Blaniks off cause).

Controls: Spoilers

When releasing the spoilers [in Max's Grob Astir model in fs9] the nose goes down significantly, and, eventually, you need to pull to maintain speed. All gliders I know from reality (but not the CS) does the opposite, at least you need to push to maintain the speed.

The Vne is definitely in true airspeed. If you use IAS the Vne is to be decreased as a function of the altitude

For my ASW 27 the flight manual gives the following values:

<3000m   280 km/h
<5000m   247 km/h
<7000m   221 km/h
<9000m   197 km/h
<11000m  172 km/h
<12000m  159 km/h 

I have flown the full size Genesis 2 and found the glider different to fly, it's very light on the elevator due to the size and distance from the wing. The leading edge is very sharp and I think it had a better performance than the Discus 2 above 80 kts.

I measured the decent rate at Parowan decsending from 16K to 6K with gear out, full flaps and full dive brakes at 70 kias straight ahead flight from the log file and recall that it was in excess of 2000 fpm.

home | flight dynamics

Copyright © 2004 Kris Feldmann