Joined: Jun 07, 2007 Posts: 34 Location: Nr Sheffield, South Yorkshire
Posted: Sat Jun 23, 2007 12:04 pm Post subject: Flying inverted?!!
Can anyone settle an arguement with regards to full size helicopters flying inverted (upside down). I know it is possible with model R/C helicopters which are set up for 3D flight, but there seems to be a great difference in opinion as to, if and what full size heli is capable to do this!
Joined: Oct 24, 2005 Posts: 70 Location: oop north
Posted: Sat Jun 23, 2007 2:26 pm Post subject:
flying upside down or hovering?
models can do either for several reasons , power to weight is much larger than full size, model blades are much stiffer than full size so do not cone nearly as much , pitch amounts are greater - a model can have a pitch range of -10 to +10 degrees of pitch quite easily so can hover inverted using its negative pitch.
some full size helis can 'fly' inverted in as much as loop and roll but not for sustained periods , indeed loops are generally not a true loop more an 'e' shape as the aircraft is falling when inverted also in a roll
hope it helps, short answer is models can full size cant _________________ R22, H269, R44, B206, EC120, AS350,
it is all up and down in this job...........
I am sure that several of you have seen the Blue Eagles. The Lynx AH.7 displays a complete loop. During the display they also make some sort of loop. Don't know the right name (backlid??) for it, sorry. But the pilot pulls the Lynx backwards and makes a loop without losing altitude actually. Amazing to see. Have to dig for some photographs...
Joined: Feb 20, 2005 Posts: 62 Location: Bristol/Bath
Posted: Sun Jul 29, 2007 7:21 pm Post subject:
Anyone who was fortunate enough to be at the Red Bull Air race in London today, would also have been witness to some fantastic inverted chopper flying from a Lynx and one of the Red Bull Team heli's - absolutely spectacular - loops and rolls !
Joined: Aug 23, 2005 Posts: 266 Location: On a course.... golf course
Posted: Tue Jul 31, 2007 7:36 am Post subject:
Full-size helicopters cannot maintain inverted flight. There is no facility for negative pitch in flight (some navy helos have negative pitch for when they are on a ship's deck), which you would need, and the aircraft is statically and dynamically unstable.
Inverted flight is possible during loops, barrel rolls etc while positive G is held.
Bolkow heads and some military machines are able to withstand negative G, down to -1, during push-overs and hammerheads, but that is not sustained flight.
Most helos hang below the hub, giving static stability, and like a bucket on a chain, can be moved around. But try to get a bucket on a chain to stand upright inverted. Doesn't work.
Other reasons are:
* Engines for helos don't have inverted flight sumps, so you would rapidly run out of oil.
* Before that happened, you run out of fuel, for the same reason.
* Your brain couldn't cope fast enough with the reversed inputs required to stay on top of the rotor
* You would be killed by the blade entering the cockpit before the engine flammed out or the transmission seized.
The Red Bull helicopter was the headliner at this years Vertical Challenge Helicopter Air Show. Chuck Aaron, the pilot, and the entire Red Bull team were wonderful to work with. Their show was awesome.
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