Aeros Discus 12, Owner'S Manual

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Warning: It is important that you do not take off with VG on more then ½ length of VG rope. The glider with VG
more than ½ on becomes easier to stall and the roll response gets longer. With low speed during take off it can lead
to unintended stall.
SPEED TO FLY
The range of trim speed for the Discus with VG off is 33 - 35 km/h (21-22 mph). The speedbar position in front of the pilots
face corresponds to this range.
The range of the stall speed for the Discus is 29 –30 km/h (18-19 mph). The glider is stable at the beginning of stall. While
pushing out the basebar, the bar pressure is progressive.
The Discus speeds up to 80 km/h (50 mph), being essentially roll neutral, with no tendency to yaw. The bar pressure is
mild, but progressive and consistent.
With the VG on the trim speed range for the Discus is 33 – 37 km/h (21-23 mph). The basebar position opposite the pilot’s
neck corresponds to this range. The pitch bar pressure decreases with the VG on. The handling of the Discus with VG on
becomes stiffer, but within permitted limits.
AEROTOWING
Special care must be taken in any form of towing.
We recommend that the VG be set to off prior to launch. This provides the best qualitative flight characteristics for flying in
formation with the tug at normal aerotow speeds.
If you choose to launch with some VG on, fix the excess VG rope on the control frame so it will not interfere with
the construction of the cart during take off. Make sure that all the harness ropes are hidden inside the harness and
will not get tangled on the cart during take off.
If possible, it is best to adjust the keel cradle on the cart to re-set the glider to the proper angle of attack. For Discus the
best angle of the keel tube in relation to horizon is approx. 18 - 20 deg.
If it is not possible to re-adjust the cart, recognize the launch will be more demanding, and more dangerous, as the glider
will have an increased tendency to leave the cart at a lower speed, where lateral control is reduced, and the tendency to
come off the cart with one wing low is increased. To some degree, this can be compensated for by pulling forward through
the control bar to position the basebar below your shoulders, and holding tight to the hold down rope. This will cause the
glider to raise the keel as it begins to develop enough lift to lift out of the cart. At that point, and not before that point, you can
release the rope and ease your weight aft to fly the glider off of the cart. Be prepared to pull in once clear of the cart if
necessary so as not to climb more quickly than the tug.
Once clear of the cart and in the position behind the tug, use firm lateral movements of short duration for roll and directional
control in order to stay in the position behind the tug. Do not move to one side of the bar and wait for the glider to respond -
this will lead to over control and being out of position, and may lead to roll / yaw oscillations. It is better to "bump" the glider
firmly in the direction of the desired correction and then return to center. If you need more correction, bump again. In pitch,
stay on top of the situation and be as aggressive as necessary to keep the tug on the horizon.
Get appropriate training for aerotowing!
TRIMMING YOUR GLIDER IN PITCH
You will find that the pitch trim of the Discus, as well as the basebar position at trim, changes with VG setting. At VG loose,
the Discus will normally be trimmed closer to stall, than with the VG tight. The bar position at trim at VG loose will be
relatively far out. As you set the VG tighter, the trim speed will normally increase and the trim bar position will move back.
At tighter VG settings, the amount of pitch pressure felt as you move away from trim also decreases.
At VG loose, the pitch is very well defined, and the pitch force increases quickly as you pull in from trim speed. At tighter
VG settings, the "pitch well" becomes more "shallow," and the pitch force increases much less as you pull in from trim speed.
Overall pitch trim is affected by several factors. Among the most significant is the location along the keel of your hang point.
The farther forward your hang point is, the faster the glider will trim, the less effort will be required to fly fast, and the more
effort will be required to fly slow. If the glider's trim is too slow, it will make the glider more difficult to control in roll, especially
in turbulent air and when the nose pitches up on entering a strong thermal.
On the Discus, hang loop fore and aft position is adjusted by repositioning the kingpost on the keel.