RC India

How Flat Wing Foam Planes develop Lift without airfoil? :headscratch:

My answer attempt....

Some one I know had a pretty interesting analogy/explanation. "It is just a heli going sideways"  8-) 

There is no "lift", just a prop keeping on carrying it forward, just like a paper plane floating in the air ONLY WHEN it is thrown with sufficient force and its shape (or angle of attack, rather) is conducive to such "skidding" through the air.

just like any other airfoil...but then they are really inefficient ones and produce a lot of drag. That is why you see them mostly in foamies which are always over powered and fly on prop rather than on wings. you will never see it on a plane with thrust to weight ratio less than 1...or you'll not see the plane any longer in air.

(even a barn door can act like a airfoil when at an angle of attack...but it also produces a lot of drag)

How does a flat bottom trainer with dihedral fly inverted? The "LIFT' should push the plane downward. but by changing the angle of attack using the elevator, one does manage to fly it inverted.
Avijit

I had seen a few non-coaxial helis without a tail rotor. How/Why is it possible ?

I haven't seen RC ones yet (didn't investigate yet), but I see full size helis all the time like that. The air-ambulance helis used in Qatar are these types, and have seen them up close when they land on highways here to pick up accident victims.  Was quite intrigued initially by the lack of a tail rotor.

They way they work (I guess this is one of the multiple possible designs) is that they have a jet of air which is generated somewhere near the main engine itself, and this jet is pushed through a hollow tail boom. Finally a vertically placed control surface at the end of the tail moves to direct the exhaust of that jet of air, determining the tail movement.

http://en.wikipedia.org/wiki/NOTAR

What Qatar uses seem to be the MD600N. One the contract pilots for the same used to fly RC helis with us, but left after completion of contract.  He is still remembered in the field for the canopies of the Trex 450 helis which he himself used to paint with some kind of illuminated paint (it was bright orange with a black canopy area)....  super visible even when these small helis are pretty far away.

This video (already posted here before) talks about single rotor RC helis without any tail rotor. 

http://www.youtube.com/watch?v=kvP_bZt65d0

I did not quite understand how they work (did not dig deep into them yet), but Kyosho used to make production models like these.

Is it really possible to perform, the extreme maneuvers expert RC Heli Flyers do, with real life full size Helicopters? 

Not really, there are machine limitations and human limitations. The BO 105 is probably as exciting as it gets with real helis. Real helis are not built with the intention of flying inverted or with high piro rates. No real heli has enough negative pitch for holding inverted, at least in my knowledge.

I have seen a video where some one measured the g forces on an rc heli. It routinely exceeded 20G.  A fighter pilot experiences maximum of 9G that too for a very short duration. This is generally considered the limit of endurance for a very fit human that too with the help of g suits. Most people will black out before that. And the piro rates like in a rc heli will make any pilot dizzy.

what i know about g forces is that any normal human[fighter pilots don't fall under this  category as they are given necessary training to make it suitable] would only SAFELY withstand less than 5g force
force >5g is dangerous

also if u fly inverted in a real heli then wil be "sitting on the roof" so u may[if not properly pre-equipped ] fall down[rare chance] nut however u can put ur life to  a serious risk.

source: info entertainment shows talking about g-forces/planes/helis etc
and my "weak" gk