can it be done? slope soar a helicopter

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27 May 2014 16:25 #16 by Quorneng
Replied by Quorneng on topic can it be done? slope soar a helicopter
Keith T
Surely if you hold a helicopter nose high into the wind with negative pitch on the blades they will rotate just as does any autogyro.
Once sufficient rotor head speed has been obtained it will also fly just like an autogyro except it will have a functioning tail rotor rather than a rudder.
So provided the angle of the wind up the slope exceeds the speed & glide angle of the gliding helicopter it will stay up.
The best glide angle for a full size helicopter is about 4:1 but I would expect models to be rather worse so compared to the average slope soarer the wind would have to be pretty strong and the slope pretty steep! ;)

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27 May 2014 16:50 - 27 May 2014 16:54 #17 by Keith T
Replied by Keith T on topic can it be done? slope soar a helicopter
The wind would have to be insanely strong indeed :ohmy:
So strong, the pilot wouldn't be able to stand up in it - top or bottom of the slope :woohoo: lol
And we are talking something around 1200 rpm headspeed - not something you'd want to hand launch TBH!
I've no idea as to the actual equation, but any auto-rotation uses the model's weight to force the air over the (-ve pitch) rotors and therefore keep them spinning, during what is a controlled free fall, but this is with the rotors starting at perhaps 1700 rpm on a big model. Once on the way down, a complex mix of zero/positive & negative pitch allows the helicopter to 'float' down, but the pilot has to keep enough energy in reserve to allow the free-fall to be temporarily stopped through the use of positive pitch, just before the crash. That's obviously the first really hard bit; the ground is the second! Get the attitude even slightly wrong and the heli will plunge. Once that starts, it's unstoppable without the return of power. No need to ask me how I know!
The application of positive very quickly dissipates the inertia of even big blades and you generally only get one shot at it.
Flybarless systems have even less hang time than the old flybars and regularly cause 'white face syndrome' :S
Don't forget, the pilot also needs enough energy to pick up all the bits afterwards too :whistle:
Tee hee!
Keith

With sufficient thrust, pigs will fly!
Last edit: 27 May 2014 16:54 by Keith T.

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28 May 2014 06:31 - 28 May 2014 06:33 #18 by locky
Replied by locky on topic can it be done? slope soar a helicopter


OF course it can b done . the principles of slope work different to normal field flying . for a start lift is already present once blades are spining .
Last edit: 28 May 2014 06:33 by locky.
Thanks: blue123

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28 May 2014 06:41 #19 by bogbeagle
Replied by bogbeagle on topic can it be done? slope soar a helicopter
Great video. Not sure that it ended too well.

OK, your task is to produce a PSS heli ... should slope pretty well, if it's properly thought out.

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28 May 2014 08:57 #20 by locky
Replied by locky on topic can it be done? slope soar a helicopter
HA no problem . the point being is on the slope a heli is more autogyro . think of it like this and it all makes sense.
Wind thru the rotors is from slope lift and forward movent is just the downward momentum until climb lift speed of rotors is obtained .then they become rotor wings and fly on the slope lift . easy . ..

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28 May 2014 09:16 #21 by Keith T
Replied by Keith T on topic can it be done? slope soar a helicopter
Clearly should have googled it :oops:
The guy holding it has more nerve than I would and the look on the pilots face at the end, is strangely familiar :S
Great video, thanks for clearing it up.
Keith

With sufficient thrust, pigs will fly!

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