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Actually gyrocopter rotors and helicopter rotors use exactly the same types of airfoils. The only difference is that a helicopter can use an engine to turn the rotor, while the gyrocopter uses the airflow through the rotor to turn it. Helicopters do exactly the same thing when we glide with the engine shut down/disconnected. There are many different designs, but generally speaking gyrocopter and helicopter rotors are identical except that helicopters may use an engine to power the rotor.

If you want to check out a couple links on my helicopter website that discuss this:

http://www.copters.com/helo_ae...
http://www.copters.com/aero/au...

Actually gyrocopter rotors and helicopter rotors use exactly the same types of airfoils. The only difference is that a helicopter can use an engine to turn the rotor, while the gyrocopter uses the airflow through the rotor to turn it. Helicopters do exactly the same thing when we glide with the engine shut down/disconnected. There are many different designs, but generally speaking gyrocopter and helicopter rotors are identical except that helicopters may use an engine to power the rotor.

If you want to check out a couple links on my helicopter website that discuss this:

http://www.copters.com/helo_ae...
http://www.copters.com/aero/au...

It's 1/2 rotor diameter...
http://www.copters.com/aero/ground_effect.html

To be a real helicopter, it needs to be able to fly out of ground effect.
This would be at least a height equal to the diameter of the propellor, or 40 meters height about with the current prop.

Under this height, it gains significant advantage from being next to the ground - it's behaving like a hovercraft, not a helicopter.

See the nice graph at http://www.copters.com/aero/ground_effect.html - two thirds of the way down.
At 1/4 (10m altitude for the above device) the thrust is 20% better than at altitude.
You could in principle make a free-flight helicopter by bolting two http://en.wikipedia.org/wiki/MIT_Daedalus 's to a light spar, so it's in principle possible.

Like other people are saying: digital has film beat for low light work. I did a project which I first tried to shoot on film. Couldn't do it - available film wasn't sensitive enough. The Nikon D3 allowed me to take these: http://photos.copters.com/p404438907

... or the stupid plane V22, ... that boondongle from Fort Worth, V22 Osprey.

Why the animosity against the V22? Is it Bell's execution of the design, or the design itself?

Granted, making the V22's rotor large enough to support hovering leads to a vastly over sized propeller in forward flight. Other than that, it sure seems to me, executed properly, a tilt-rotor truly gives you the best of both worlds. A VTOL aircraft with the speed of a fixed wing has long been a dream of aviation, especially the military.

I'm curious about your strong opinion because my brother-in-law worked on the Osprey project, but couldn't ever talk much about it due to the military angle...

Back on topic, autorotation in helicopters isn't an easily understood mechanism. I suspect this design would have something similar, as a combined lift+drag vector forward of the shaft-to-wing vector on part of the circuit could keep the main shaft spinning just like it does a helicopter's rotor... Granted, the glide angle is probably pretty abysmal, but it is in helicopters too. All that's needed is to get you close to the ground so you can use up the remaining rotor momentum in the flare.

There's also the possibility of stopping the rotor and gliding down as a fixed wing, but that's not as easy as others might make it sound... There would be issues maintaining lift during the transition, controlling the individual airfoils' AoA, plus you wouldn't normally have ailerons or elevators, so basic control could be difficult.

BTW, IAAHP

Don't know about reserve tanks, but helos have another option to get down in a somewhat controlled fashion if the engine goes out. It's called autorotation.

The torsion created by each set of rotors balance out, preventing the need for a tail rotor to prevent spinngin. It was one of the upper rotors that hit the lower rotors in this case, which is thought to be due in part to heat and humidity (probably since the top rotors were longer, the heat and humidity caused them to bow, and they didn't generate enough lift to pull themselves out of the way of the smaller lower rotors as they lifted up).

Some more info here

Ground effect does not apply to this type of aircraft.

For an airplane, "ground effect" is the term applied to the tendency of a wing to exhibit increased aerodynamic efficiency (basically more lift and less drag) when it's within roughly a half-wingspan of the ground. It's caused, at least in layman's terms, by a cushion of air forming beneath the wing and the ground, and by the reduction of a drag-inducing wingtip vortex.

This vehicle has no horizontal wing flying thru the air. So we can eliminate the obvious cushion of air.

Now, a helicopter demonstrates ground effect for the same basic reason as an airplane, within half a rotor-disc-diameter or so of the ground, and also because for a hovering vehicle, the downwash tends to bounce back up again to provide a additional cushion. Here's a primer on helo ground effect. As you can see, the ground effect is largely produced by the ground limiting development of a tip vortex.

Just for completeness, we can also address ground effect for a hovering jet, like the Harrier Jump Jet. In that case, the downwash bouncing up certainly provides a cushion, and the Harrier has strakes under the fuselage designed exclusively to capture that cushion of air and enhance it - kind of like a hovercraft. But for a hovering jet, you have an additional problem - the exhaust gases also tend to get reingested by the engine, lowering the engine efficiency. One of the most vexing problems for the Harrier, and also for the newer Joint Strike Fighter designs, is "hot gas reingestion". In fact, if you hover these aircraft pointing downwind, you can snuff out the engine due to lack of oxygen. (This issue is probably not a big problem for the high-bypass arrangement of the SoloTrek, where very little exhaust gas is produced.)

Now to address this vehicle. The lift is provided by ducted fans. Therefore there is no tip vortex, because the duct prevents one from forming. In fact, the duct itself provides the same effect as ground effect, by eliminating the efficiency loss due to the vortex. The only relevant part of the "ground effect" here is therefore the bouncing cushion of air. But the fans on this vehicle are mounted so high above the ground (about 7 feet), and the total thrust is so low, that a fairly minimal ground effect cushion can be developed. In fact, in the pictures on Ebay, at least one of the photos shows the thing high enough up (the fans are at least 12 feet off the ground) that any ground effect that might exist would be almost totally eliminated.

So it's extremely unlikely that this vehicle's performance would change significantly with climbing away from the ground.