A thought?

[craig]

I have long had the idea for a new way of generating lift and wonder if it has ever been tried before?

My idea is similar to the cylinder type fans which you may have seen in heaters etc. They have fixed blades, can lie in any orientation and essentially just move air.

However what if the blades were able to pitch so the force was able to be directed to the same hemisphere no matter what point of rotation

If you imagine the cylinder in cross section (through its axis of rotation), it is a circle.

Now consider the cross section at 4 points of rotation. For simplicity lets call them North, East, South and West. Assuming clockwise rotation. The blades would be able to pitch through neutral so as to be producing no force at West and East positions. As the blade moved from the West position (neutral) to North it would gradually increase its positive angle of attack reaching a maximum at the North position, then gradually back to neutral as it passed through East. The blade would then pitch through neutral, reaching a maximum negative angle of attack at the South position. The blade angle would then again gradually reduce to be neutral at the west position.

Over all the total effect would be a force in a Northerly direction.....

[lumpy]

Sounds very similar to the way helicopter rotor heads work ?

[snaphead]

there used to be a toy kite which operated on the same principal.

[craig]

Dec 14, 2013 8:30:24 GMT 12 lumpy said:

Sounds very similar to the way helicopter rotor heads work ?

Yes similar in the sense that it has advancing and retreating blades. But of coarse the blades have different orientation arranged lengthwise along the outside of the cylinder.

I envisage these cylinders could be used in banks arranged to support whatever platform was required. They could be inclined to create forward thrust and level of lift could be manipulated by speed of cylinder rotation more rpm more lift.
Definite down side would be no auto rotation option. So would need ballistic recovery chute.

But would the theory work???

[ryand]

To me the theory is good aside from one rather large downside. A helicopters rotor disc produces lift over its entire area, obviously in a hover it is equal and in forward flight there is the off dissymetery of lift and retreating blade stall etc etc, but the point is all blades are providing lift for flight. To me it sounds like with your theory, only one blade of the four would actually be able to produce lift at a time. This could well work but it would have to be an enormous blade to provide the lift required. Times the weight by 4 for the number of blades and you have a large rotational mass, requiring a massive amount of energy to turn it. Sounds very inefficient?

I may be entirely wrong/not have explained myself very well. If anyone can clarify what i'm trying to say that would be great and if you have thought of a way to counter these problems i'd love to hear it. Cheers

[Bruce]

A bit of research suggests that it may just work - A Korean University has a flying model already:



I can't quite see the mechanism that gives a positive thrust vector, but I assume it has some kind of cam follower arrangement to give neautral thrust on the vertical sectors and positive on the horizontal.

[Bruce]

en.wikipedia.org/wiki/Cyclogyro

[ryand]

I stand corrected,very cool

[craig]

Thanks Bruce..... Back to the think tank!

[suthg]

Hmmm four drums with four fan blades each - must have given it the equilibrium it needed - fore and aft and sideways variability and control. There is a fascinating video of a quad copter around - totally computer controlled and balanced.

Oh here...




Watch it with a wine glass of water sitting on top of the quadcopter (at 5:30 >) and the sharp movements it does without spilling a drop!