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Power launch


AndyB
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With the help of Dan, who I fly with, I think I have got power launch working well now. I have settled on about half power. On one launch I had too much power and my thumb was pushed through the A triangle link and got stuck! 

I've found the best way for me is to be set up with A's just held taught, Then lean forward enough so that the prop blast does not hit the wing. Put throttle to half power. Then start to run and straighten up at the same time so the prop blast now launches the wing. Video below yesterday.

 

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3 hours ago, MagMen said:

That’s the way people end up busting props Andy. Don’t lean forward at all, lean back and let the power do all the work.

 

I don't understand your comment. Even the video you post shows the guy running the engine up with it angled such that the prop blast does NOT hit the wing. 

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Ok, I was confused by your initial text as you talk about leaning forward. Constant power or continuously increasing power through a power launch but as the motor is supposed to be doing all the effort you really don’t want to be coming off power unless aborting.

Edited by MagMen
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Hi, thanks. What I have found is that it it can be quite difficult to put just the right amount of power on and hold it there. By directing the prop blast above the wing to start with I can select half throttle, hold it there, then launch by standing up straight and starting the run all in one go.

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I always power launch using thrust to bring up wing. I dont worry about directing prop blast away from wing...there is no need to do that.

If you wing is having problems coming up through propellor wash then i would suggest one of two things

1. Ensure you fly a reflex glider....i have found they are better for power launching up through prop wash than standard paragliders (just my experiences)

2. Dont rev engine so much initially whilst wing is coming up. Because of the .oving airflow created by prop,you actually dont need much to get the wing coming up. Think of how little wind is needed to reverse launch and kite a paraglider these days. 

 

When foot power launching, the initial thrust is only a small amount to get wing up. As the wing passes 11 O'Clock, then begin to further open the throttle, increasing to take off thrust as you run forward (i can usually feel in my body the right time to open throttle more but i still regularly stuff the timing when i havent flown much).

Too much power launch thrust too early will see the wing surge far too quickly then your body wont be able to get moving fast enough to keep up with it. Essentially it will lose its energy above your head and very quickly begin to settle back down to the ground again (at the worst possible time). Your efforts to then get moving will suddenly become very very difficult as the wing is then a big parachute because its not flying anymore. And thus is when i find im in danger of getting a line tangle around prop. If wing settles back to ground there are 2 things i try to do to hopefully avoid tangle

1. Dont turn around if wing is already behind me settling to ground (keep facing forwards

2. If possible try to encourage wing to fall evenly back down level (not so easy as wings not flying almost always immediately go offline to side)

3. Immediately shut down engine (actually this is the first thing one should do...i should have it first in list)

Its a matter of experimentation until you find the right amount of thrust needed.

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You are absolutely correct!

And since a reflex have better pitch stability then a regular profile it helps to not overshot as aggressive as a regular wing might do.

When doing the mistake with too much power the risk of a collapse over your head is big! You just have a very short time to respond with the kill switch and hope for the best as the wing comes down. If it is high and you feel the collapse, don't try to correct it you just waste time as it will fall lower behind your back. Kill, rotate and step away, this will save the wing and lines. Correction can be done if you have wind, but in nil wind it will require so much forward speed.
If you don't start to turn around fast enough, then do what Adam suggests, try to get the wing down evenly, hands out and follow it down. Nerve-racking to let if fall down when you have a propeller that might still be spinning, but higher chance to save your lines.

Just a little thrust is needed for the wing to fly nice, then full thrust right after to move yourself as quick as possible. With the right instructions like this it should be possible for a beginner with little risk of damaging your gear. When looking at trike launches they just keep pushing forward, compared to foot launch where the pilot not necessary run as fast as needed. And we also lose balance easier where a trike can force it's way forward and recover the collapse much easier. They also have it easier to pull hard brake to stop the wing from surging forward. Compared with foot launch where we have to struggle with the running and the fast shifting from A riser to brake pull. So conclusion, right amount of thrust and it's almost as easy as any forward lanuch.

There is also a method to do a power reverse running launch, where you step to the side and hold your risers low, add thrust to create the air stream, then rotate sideways and side step forward as the wing goes up, always done to the opposite side of your throttle to keep it clear if something goes wrong. Exemple: left hand throttle, hold risers with even distance in right hand, pick A risers with the left and pull. When doing this you can complete the rotation ones the wing is on it's way up and then keep running. You can safety practice this in light wind without any power, and it gives full visual of the wing. Very few pilots do this (looks sketchy :P). Try it with just a harness in nil wind and you see that it's actually easy to do a running reverse, but much harder with weight on your back. 

This is also an interesting topic if someone considers pros and cons with clutched engines. When we talk about the benefit of clutch for a regular forward take off. Then it's very clear that it's a huge disadvantage for forward power launches if something goes wrong. But know that we know how to do it right, then it shouldn't be any problems :)

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