Another Look at 1930's Cyclogyro Plane Design

trogador writes to mention that a group of researchers is taking another swing at the idea of a cyclogyro design for a UAV. Even though the cyclogyro design was invented in the 1930's there are no records of a successful flight. "Cyclogyros have the potential to be highly maneuverable flying robots due to their method of operation, making them potentially more suitable for complex tasks than helicopters and other micro air vehicles (MAVs) with less maneuverability. The biggest challenge in designing the cyclogyros is varying the angle of attack of the rotating wings. This ability would enable the plan to change altitude, hover, and fly in reverse. To achieve this quick angle variation, the researchers introduced an eccentric (rotational) point in addition to a rotational point connected to a motor."

Same fuel consumption as helicopters

[140Mandak262Jamuna]

In a fixed wing aircraft the engines develop enough thrust to overcome the drag. Typical Lift to drag ratio is between 10 and 12 for commercial jets. Some sail planes and gliders have achieved L/D ratio of 30 and 40. In any hovering aircraft, be it helicopter or vectored thrust machines like the Harrier, or the stupid plane V22, the engines must develop enough thrust to overcome the weight. (Weight = Lift). Thus they develop between 10 and 12 time more thrust and thus they consume that much more fuel. That can not be avoided.

Changing the angle of attack of each foil in the wing for this aircraft is no doubt complex, but even helicopters have this quite complex cyclic pitch/total pitch changing mechanisms. Given the advancement in materials and electrical actuators, it is possible that the time has come for a horizontal axis rotating wing aircraft.

May be this craft will transition from hover to flight with locked wings more easily and more stably than that boondongle from Fort Worth, V22 Osprey. Thus for the long haul you get the speed and efficiency of the fixed wing aircraft. But you get hover ability too. The price you pay is to haul a larger powerplant all the while. But still it might beat V22.

Re:Goldberg to the Rescue...

[Rorschach1]

Yeah, as I recall, one of the drawbacks of this design is that it can't glide like a plane or autorotate like a helicopter. If it loses power, it's coming DOWN. For a UAV that's not a big problem, I suppose.. though I wouldn't want to be underneath it.

For that matter, a large-scale model would be a little scary to be around during takeoff and landing. I've done hover loads on a Huey (climbing in while it's hovering about 3 feet off the ground) and it still feels like the rotor's about to take your head off. Not to mention how it blows dust and gravel everywhere. This thing would be like a whirling death machine.

Still, for a small, agile robotic observation platform, I can see where it'd be useful. But with several decades of experience with helicopters behind us, I doubt it's going to happen unless there are some VERY compelling performance differences.

Re:Seeing as the link to TFA is dead ...

[colourmyeyes]

http://www.networkmirror.com/fDZs3ol_RaN_NoOY/www.robotworldnews.com/100194.htm [networkmirror.com]

and here's another, a mirror of the original article.

Re:Seeing as the link to TFA is dead ...

[fewnorms]

Dammit, posting the actual link would have helped here. Anyways, for the rebound:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/cyclogyro/cyclogyro.htm [pipex.com]

Re:Like a helicopter?

[140Mandak262Jamuna]

Yes, helicopters do it too. The advancing blade meets the air at aircraft velocity PLUS velocity due to the spinning of the blades. The retreating blade meets the air at rotational velocity Minus aircraft forward speed. Thus to produce the same lift, it has to have a higher angle of attack. This is done by the cyclic pitch control. Depending on the total lift needed the angle of attack has to be increased for all the blades by equal amount. That is called the total pitch. It does make the hub mechanism of the helicopter blades very complex.

A different link with Video!

[Xoltri]

http://serve.me.nus.edu.sg/cyclocopter/ [nus.edu.sg]

Re:Gyroplanes today.

[querist]

There is a difference between the cyclogyro and the autogyro (gyroplane). The cyclogyro uses powered rotating wings to generate the lift. The engine actively turnes those rotating wings, which rotate along the sides of the aircraft.

An autogyro, however, uses a propeller, just like a fixed-winged prop-driven aircraft, to generate thrust. The rotary wings are on the top of the craft and are _not_ driven by the engine. They are in "autorotation", which means they rotate because of the other stuff going on around them (movement relative to air d/t thrust, etc). This autorotation (one-directional clutch) generates lift.

They are very different aircraft. The autogyro / gyroplane is well known and understood. The cyclogyro, OTOH, is a bit of an odd design. It would be interesting to see one work.

Re:Like a helicopter?

[140Mandak262Jamuna]

The tail rotor is needed to "anchor" the engine. If you clamp the shaft of a motor, the motor would spin in the opposite direction. Infact most ceiling fans have a fixed shaft and the motor spinning in the opposite direction. Most other applications of the electric motor has the motor bolted down and the shaft spinning. In a helicopter, how do you "bolt" down the engine? To the airframe? The whole airframe will spin in the opposite direction. That is why you need a tail rotor to provide a counter moment to keep the aircraft from spinning. You can avoid tail rotor if you have two main rotors like in a chinook, or two counter rotating main rotors. You could create a small jet using the gasturbine's exhaust and use it instead of the tail rotor.

Why does it not generate lift in all directions? The Lift is always perpendicular to the blade/wing surface that is true. But the magnitude of the Lift depends on the angle of attack. So when the blade is in a position where you don't want lift, you can change the angle of attack and make it zero. You do it while you are swimming. Imagine the breast stroke. To move forward you have the palm pushing water back. Then you move your arms and bring it forward, but keep the palm cutting through the water without creating any force by pushing water forward. Same thing but you need to do it using a mechanism to keep the angle of attack the precisely right.

Re:Same fuel consumption as helicopters

[Rakishi]

Basically, its current incarnation lacks both the defensive survivability (autorotate on failure)

Can't it glide, somewhat, like an airplane?

offensive armament of helicopters (all it has is a small machine gun, pointing backwards, that you have to OPEN THE DOOR to fire),

Yeah because the average CH-47 Chinook or C-130 Hercules are such massive gun ships, always used to shoot at the enemy. God forbid someone just wanted to move cargo or people with a helicopter or airplane. If it doesn't have enough firepower to level a small town it's useless period.

The current V-22 is a cargo plane more or less, it's designed to quickly and efficiently drop people or cargo where needed. It's not supposed to stay around and shoot at the enemy, most likely trying to fight back will just make it a much better target (and helicopters in general are easy target).

trading both for a slightly higher top speed.

And longer range likely.

Re:Flying through its own downwash = bad.

[billybob_jcv]

So... I'll pull rank back - my degree *is* in aeronautical engineering. Lift is generated by an airfoil by the pressure differential between the upper and lower surfaces of the wing. The pressure differential is caused by the higher velocity of the air molecules over the curved upper surface of the wing as compared to the lower surface. A symmetrical, uncambered airfoil at zero angle of attack generates *zero* lift because the velocity above & below the wing (and therefore the pressures) are identical. That relationship between mass flow and pressure differential *is* the Bernoulli principle. Now, a pressure differential does result in a net force - that's the lift being generated. There is also a downward deflection of the airflow that results from a airfoil when it is cambered or at a positive angle of attack. However, "downwash" is exactly what the other poster described - it is the result of air spilling from the upper to the lower surface at the tip of the wing causing a vortex at each wingtip. The wingtip vortices create the "downwash" effect that causes problems for airplanes that fly too closely behind large planes. http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html [nasa.gov]