Ultra low head speed Helicopter design- what will happen?

I found some people on similar idea here:

http://hoytstearns.com/AHSpresentation/

using cross flow fans to drive the rotor. I believe the owner of two patents is registrered on this forum

his patents nr are: 4,702,437 and 4,720,059

and his forum name is:hstearnsjr's

Kalle

Kalle,

You may wish to compare the efficiency of the Fanwing to that of the Cyclogyro, since the two have some commonality; at least from a fixed wing perspective they do.

The bottom of this page has links to outside sources of information on the Cyclogyro.


Dave

the efficiency of the cyclo gyro is poor besides the utter complex structur of it.

structure faitgue is a donkey we have to deal with ,

If it is a electricmotor+propeller that is going to drive the rotor, it better be very small compared to the 33ft rotor. A propeller diamter shoudnt be more than 12". A high speed steep angle 12" is efficient, that is. But, 12" could still produce very unfavourable gyro effects. A smaller 8" would be nice but that prop would be a screamer and inefficient.

Hmm Il have to choose between efficiency but danger of a bigger prop, and guranteed safety but horrible efficiency, Il choose the latter... perhaps...



There is aproblem rearely and never discussed anywhere about tip driven helicopters

We need a "flexible/ rotatable electrical cable joint" that goes through the rotating mast

The D'Ascanio helicopter

The D'Ascanio helicopter

D'Ascanio helicopter

Here is the low rpm helicopter I wrote about. I still havent found the video yet, seems like an impossible thing to find
http://www.aviastar.org/helicopters_eng/askanio.php

Engine: 95hp
Weight 800kg


From the video the rpm seemed low, as one can follow the blades with sight albeit a little bit fast for the eye. No, it wasnt camera frequency-synchronisation

Here is the video


http://www.facebook.com/pages/Alexa..._2392950137#!/video/video.php?v=1142097082366

I always wondered how the kamov-26 keeps its blades from striking each other. They dont look very rigid and the gap isnt big either

http://en.wikipedia.org/wiki/File:Peenemuende_museum_04.jpg

Leviterande

In theory I suppose you could bolt Cessna wings on a shaft and rotate them to get lift. They are stiff enough and if they could see 60 mph average airspeed you might get off the ground. Lots of drag, poor gyroscopic stability , and the thick chord required for internal stiffness are all disadvantages. Not to mention the heavy controls required to move them.

For those and other reasons most rotors are small and turn at higher rpm. Centrifugal force becomes your friend because it supplies the stiffness required in a slender lightweight blade. Gyroscopic stability and cyclic control are very good. Control forces are light.

Because of the higher air speeds (of the small blades) a different set of problems emerge but it has been the mainstay of the helicopter industry for years.

On the other hand I think it was Ray Prouty who said that said the most efficient rotor blade would be infinitely long and would turn infinitely slow so your thinking is not entirely wrong.

Stanley Hiller built a co-axial with very stiff rotors (picture below)

He also built a crane with long slow turning blades. I do not have the book handy but from memory they turned at less than 100 rpm (I think it would fly at 70 rpm but I am going by memory and could be wrong) (picture below)

EDIT: I looked it up and the crane rotors turned at only 60 rpm. Tip speed is still what counts most.

Good luck with your experiments.

Arnie.

Sikorsky's X2 and Eurocopter's X3

Sikorsky's X2 and Eurocopter's X3

Arnie,

Your picture of the Hiller X-2-235 with its rigid rotors causes one to wonder if rotor-craft is a Mature Industry.


Today's experimental X2, with it's rigid rotors and "Advancing Blade Concept"


is fundamentally the same as the Hiller XH-44, from 65 years ago.



~ and ~


Today's experimental X3, with its side mounted propulsors


is fundamentally the same as the Flettner FL 185, from 70 years ago.



leviterande,

What we need is a new idea.

How about a recreational version of this proposal by Stepniewski

How about a electric helicopter.


Dave

Rotor Rooter said:

Arnie,

Your picture of the Hiller X-2-235 with its rigid rotors causes one to wonder if rotor-craft is a Mature Industry.


Today's experimental X2, with it's rigid rotors and "Advancing Blade Concept"

is fundamentally the same as the Hiller XH-44, from 65 years ago.

~ and ~


Today's experimental X3, with its side mounted propulsors

is fundamentally the same as the Flettner FL 185, from 70 years ago.

leviterande,

What we need is a new idea.

How about a recreational version of this proposal by Stepniewski

How about a electric helicopter.


Dave

Click to expand...

Dave,

I am with you when it comes to an electric helicopter. There are many advantages of using simple reliable electric brushless motors in a heli.

If I ever build and fly an electric heli, it would be equiped with a generator.


But still my question is not answered:sorry: How does the kamov- 26 do it? its blades are obviously far from rigid as you can see. I know that rigidness is a solution. But many kamov coaxials arnt rigid at all.

See that pic I attached to
Kalle

Kalle

Centrifugal force.

You might find this Kamov interesting also. Coaxial - Kamov - Ka 56

Dave

Is there any formula or general rule that one can follow to know this? to know how much stiff the blades need to be to not come in contact with each other in relation to the vertical separation? From what it looks like the kamov 26 has a vertical gap of
0.1 Diameter which is rather tight. If Centrifugal force hold them apart why are there rigid rotors(I know because other advantages) but I mean isnt there a risk of the rotors to clash in a strong gust of wind or in a manouvre or even at some forward speed.

D'Ascanio let his helicopter have a gererous vertical gap, hmmm why? because of clash risk or because of gaining efficiency. I find this subject a tricky matter.

http://www.facebook.com/video/video.php?v=1142097082366


Anyway Arnie, it is as you said, the tip speed is what counts! so we can have large rotor diameter with a lighter discloading as a start point. I am not looking for any high speed ships.

Some theoretical example
A single 10meter rotor installed on a light testship of say a Gross weight 250kg should take off at an optimum tipspeed of 350fts i.e 200rpm. power required should be around 24-30hp? The power required is dependent on the coefficient of lift of the blade. The chord width is a factor as well. Predicting the results is more usual then not harder. Many factors are in the game, chord, airfoil, tipspeed, coning, etc