Just a quick disclaimer: the following statements and procedures were tested in an ArrowCopter. I expect they will also apply to MTOs, Calidus, Cavalon, Xenon, ELA, etc. They definitely don't apply to gyros like Magnis, which can leave the prerotator engaged during the take-off roll. I don't recommend you try them unless you have already done them before. Go and get an instructor to teach you first, because there is the real danger that you will flap the blades and bang up your beautiful gyro.
Usually when people want to do a short-field take-off they prerotate as high as possible and do a more or less normal take-off procedure.
I already posted in an earlier thread that anything above about 190 rrpm on the prerotator is not going to get you off any quicker. So there really is no point to strain your gear and prerotate to 240 or even more. You will not clear the imaginary 50 ft tree any sooner.
There is, however, one thing you CAN do which may get you into biiiig trouble if you don't do it properly. That's why I put the word "advanced" in the procedure's name. If you haven't donw it before, don't try it on your own. Get an instructor to show you first.
If you really need to get off the ground and over the 50 ft tree in the shortest possible distance, here is what you can do:
1) Prerotate as high as possible. And this time I really do mean it and it does make a difference.
2) Keep the stick at the FORWARD stop and go to full throttle. You will be accelerating much more quickly than with the stick held back. However, your rotor rpm will also decline. If it falls below 200 rrpm you have to abort the take-off!
3) About 10-15 km/h before reaching Vx pull the stick back (my Vx is at 85 km/h, so I pull the stick back at about 65-70 km/h). Don't yank it back but bring it back snugly over the course of about 1-2 seconds.
4) You will lift off immediately, therefore watch out to maintain a suitable pitch attitude to continue climbing at Vx.
The other day I was curious as to how much this technique is shortening the ground roll and the distance over a 50 ft obstacle. I did 9 standard take-offs and 5 advanced take-offs. The upshot is that the advanced technique shortens ground roll by about 12% and total take-off distance by about 7%. So it doubles as an advanced soft/rough field take-off technique as well.
Thought you might be interested in that.
-- Chris.
Usually when people want to do a short-field take-off they prerotate as high as possible and do a more or less normal take-off procedure.
I already posted in an earlier thread that anything above about 190 rrpm on the prerotator is not going to get you off any quicker. So there really is no point to strain your gear and prerotate to 240 or even more. You will not clear the imaginary 50 ft tree any sooner.
There is, however, one thing you CAN do which may get you into biiiig trouble if you don't do it properly. That's why I put the word "advanced" in the procedure's name. If you haven't donw it before, don't try it on your own. Get an instructor to show you first.
If you really need to get off the ground and over the 50 ft tree in the shortest possible distance, here is what you can do:
1) Prerotate as high as possible. And this time I really do mean it and it does make a difference.
2) Keep the stick at the FORWARD stop and go to full throttle. You will be accelerating much more quickly than with the stick held back. However, your rotor rpm will also decline. If it falls below 200 rrpm you have to abort the take-off!
3) About 10-15 km/h before reaching Vx pull the stick back (my Vx is at 85 km/h, so I pull the stick back at about 65-70 km/h). Don't yank it back but bring it back snugly over the course of about 1-2 seconds.
4) You will lift off immediately, therefore watch out to maintain a suitable pitch attitude to continue climbing at Vx.
The other day I was curious as to how much this technique is shortening the ground roll and the distance over a 50 ft obstacle. I did 9 standard take-offs and 5 advanced take-offs. The upshot is that the advanced technique shortens ground roll by about 12% and total take-off distance by about 7%. So it doubles as an advanced soft/rough field take-off technique as well.
Thought you might be interested in that.
-- Chris.
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