What good does it do to keep rotating the disc after you have stowed the blades?

http://www.vranek.ch/dragonfly.htm

I'm profoundly irritated that the mirror ball and strobe lights were omitted from the final design at the last moment.

This happens every time I go on vacation.

as to how a rotating solid disk can generate lift.

it's called bs aerodynamics and it will target the aerobatic clown-copters niche. the rotating disc in this case is used to create a crash tendency in the copter, thus providing a few moments of quality entertainment.

Forget silly little helicopters with a spinning disk.

My 'invention' is an airplane wing that would consist of two sections, upper and lower flight surfaces, each like a conveyor belt in the cross section of the lifting shape of a wing. The two belts would emerge from the trailing edge, move against the air as if the airplane was moving, and then disappear together into the leading edge. Turn on the belt motors, and the airplane should go straight up even with zero forward velocity. The wing upper and lower surfaces move instead of the air. It's all relative; right?

Since it is such a ludicrous idea, I hereby place it into the public domain.

Frisbees for example?

Unless you start sticking your disk-wing underneath (which would mean a reduction in rotary lift due to the fuselage) the pilot will have really poor view back and above, which is to say the "critical six" which helicopter pilots are taught to shoot down through to kill another chopper. However, having said that, it looks like the disk will be a lot smaller than the span of the equivalent ordinary main rotor, so should be better for getting into small and tight areas.

Someone's been smoking quality Jamican.

I'd be /really/ interested to know how a rotating disc can magically assume an aerofoil shape.

"......put a wig over the inner part......"

Being a Disco 'copter it won't need a wig. A combover will be just as effective and cheaper too.

I'm not convinced by the lift properties of a circular disc either. Plus if it was any good, or for that matter no good but possible, Great Britain would have had a prototype flying in the 1950s, like much of the stuff the US is still trying to 'invent' (e.g. Rotordyne).

A helicopter gets lift and thrust by varying the angle of the blades, both across the blade to give lift (pitch via the collective control - normally to the pilot's left) and by tilting the ends up and down using the cyclic (the 'normal' joystick) to tip the direction of lift slightly off vertical - basically the heli moves its own definition of 'up' to include the direction it wants to travel in.

Once this thing pulls the blades in it will need some other method to push it forward as the disc will not be able to generate enough lift to keep it flying without something else to provide thrust to get the speed necessary to get the lift... and the inertia from the whole disc spinning one way is gonna need one hellova tailr rotor to counteract the torque...

Frisbees 'fly' because they catch a pocket of air which they ride on for a very short time - they are only marginally more efficient than a flat piece of wood compared to a 'proper' aerofoil. They are more like hovercraft - they only fly as long as their cushion is there, and they have sufficient forward momentum to maintain it - if you put a frisbee on a spinner, it doesn't take off on its own.

Oh and one final thing - other than publicity stunts, what other shape would a disc be except round??

If you're correct, and they have decent forward propulsion, this could work very well- a spinning disc that works as an aerofoil would provide lift while also providing massive stability thanks to the gyroscopic effect. The back rotor would provide a further stabalising system, meaning that when travelling at a constant speed this would probably be a good, stable platform.

So you've got a quick, highly stable VTOL platform. Sounds exactly what the DOD would be interested in!

I wonder what its radar profile would be like?

Look at the cross-section of an aircraft wing, or a helicopter blade - it's an asymmetric profile. That's the aerofoil shape. This means that even when the blade or wing is aimed level, it still generates lift.

Now look at the spinning disc, and tell me how that can assume the same shape. It can't, since it rotates. It can only generate lift by tilting the entire disc away from the direction of travel.

"Just wondered how much air-to-air chopper combat there has actually been?"

AFAIK, none, apart from exercises.

But the humble chopper *is* a fearsome weapons platform. Fixed-wing pilots are advised that the chopper's air-to-air misslies will be pointed at them 100% of the time. Heli's can hide right down on the deck, lose themselves in terrain, urban clutter or peek over the horizon with their sneeky radar/optronics masts and turn much faster to acquire a target

In all 1-on-1 fixed vs. rotary wing exercises, the fighter / ground attack pilot gets spanked He/she never even lnows what killed 'em.

Chopper vs. chopper would be much more... ...intersting.

S&K, 'cos heli's are deadly.

This could be the next Internet. We could all be flying round in giant frisbees if this thing takes off.

Yes I do remember streethawk, the bike was a road machine when on the road and magically changed into a motocross as soon as it's wheels hit grass or dirt. Amazing!