New anti-torque concept

tsheten8 · Veteran Member - Level 2

New anti-torque concept

Stingray · Administrator

tsheten8 wrote:
I have here a new concept I developed myself a long time back

:twiportal: :portalflank:

Would this be an example of contradiction?

Just kidding. biggrin

In all seriousness, this is a fascinating concept. Though, issues with stability and efficiency come to mind when I think of utilizing the configuration in forward flight.

Wish I had a better engineering point of view so I could give more helpful feedback.

Best of luck...

davh12 · Veteran Member - Level 3

Tsheton,

I've only seen this in small RC scale helicopters. Back in the 1990s there was a RC helicopter called a "Hyperfly". Same concept as your drawing, but it needed a head wind because the yaw control surface was smaller. The control surface on your drawing is larger, but just build it in small scale and see if it crashes or if it will fly. The man who designed the hyperfly still designs for certain RC helicopter fabricators. He has a you tube channel, but I cannot remember his name. Last video that I seen of him he was working on a single blade flying prototype. I've only seen the single blade in tail rotors. The hub has one rotor blade with a counter weight on the opposite end of the hub. He was flying it if I remember correctly. You tube has another video with an rc helicopter flying with not tail rotor and used a paper plate as a yaw/anti torque control surface. May be the same guy.

Dave

Flyboy · Veteran Member - Level 2

Isn't this concept basically just a variation of the NOTAR?

EDIT: Hmm, I just checked out the Wikipedia article for NOTAR and it's different from one drawing I've seen. In the article it states that there is a fan involved (which would explain what NOTAR helicopters have such a fat tailboom), but the drawing I've seen suggested that it was purely the downwash from the main rotor, funneled into a hollow tailboom and then vented out the side. And I remember correctly because at the time I remember thinking, "but surely in such a case you would need to have constantly high main rotor RPM in order to keep headed in one direction".

So I apologize if it's not like the NOTAR system, but I still feel it's worth mentioning.

tsheten8 · Veteran Member - Level 2

Thanks for the attention friends...yes,certain unknown issues pertaining to stability and efficiency during forward flight persists...but only time will tell...got to do some research and device some experiments...hey,what about getting an RC heli and experimenting the concept on it?...all I would need is some aerodynamics concept from you all...I think I should first calculate the main rotor downwash from the RC heli
in hover and forward flight...depending on the required anti torque force,I should design an aerofoil which can produce lift in all variations of magnitude of downwash...need some help...

tsheten8 · Veteran Member - Level 2

Here are some images of hyperfly Dave mentioned about...It's basically a single bladed rotor helo with a counter weight on the opposite side the hub...In my concept,I have more than a blade...

-- Edited by tsheten8 on Wednesday 15th of February 2012 07:47:28 PM

tsheten8 · Veteran Member - Level 2

Hi Stingray,I think this thread should fall under the forum Technical Research,rite?....Maybe I just started it on the inappropriate forum....sorry for that....

...

Stingray · Administrator

Tp be honest this seems more approprtiate in Builders section, that is if you plan to build concept one day.

tsheten8 · Veteran Member - Level 2

Oh!....so I see Stingray.....and yes,I am going to materialize this concept one day....

Hell(i)Master · Veteran Member - Level 1

Sorry to dissapoint You tsheten8, but Hafner experimented with this concept back in 1932. It was Hafner Revoplane RII.

-- Edited by Hell(i)Master on Friday 16th of March 2012 10:38:37 PM

Stingray · Administrator

"Feasible", maybe not. Here's some info I found here:

http://www.gyroplanepassion.com/HafnerARIIIGyroplane.html

Outside of some somewhat brief tethered flight, the design was not successful in achieving free flight.

tsheten8 · Veteran Member - Level 2

Thanks for the info Hell(i)Master...I thought that this concept I was taliking about is a new one...but it appears in the photo that the main rotor has only one rotor blade...

I am really happy that this concept is feasible...I was thinking of using this concept on my helicopter...and yes,thanks for the images....

Regards
Tsheten8

tsheten8 · Veteran Member - Level 2

Hi Stingray,thanks for the info...but can't we try to develop this concept further?...in the past,this concept wasn't possible...I am thinking of taking this concept to another extreme...

.....

Regards
Tsheten8

Kryptid · Member

I'm wondering if there would be pitch-up problems associated with it? The downwash impinging on the tail would tend to push it down and therefore lift the nose up, yes? You might be able to counter that by moving the center of gravity, I suppose. Perhaps if the tail were shaped like an airfoil with a control surface on it, it could minimize the pitching effects and better control yaw.

EDIT: Nevermind. I forgot about Newton's action-reaction law. It wouldn't make it pitch down the way I thought.

I had my own idea once for torque control; channel the exhaust thrust produced by the turbines in the turboshafts down a duct that leads to the tip of the tail. Then use a vectoring nozzle to direct the thrust in the appropriate direction to counter torque. Vary the angle of deflection to produce larger moments or smaller moments.

-- Edited by Kryptid on Friday 23rd of March 2012 01:39:51 AM

tsheten8 · Veteran Member - Level 2

Hi sir,thanks for checking on this topic...yes,the downwash would pitch the nose up...but only if the anti-torque device is laid flat in the direction of the downwash...the leading edge of the device will be pointed upwards against the downwash...profile drag of the device may induce a pitch up...but to a lesser extent...may be,not at all...

And will you please be more elaborate on ''Perhaps if the tail were shaped like an airfoil with a control surface on it,it could minimize the pitching effects and better yaw control.''....it sounds quite interesting I believe...

...

Regards
Tsheten8

Stingray · Administrator

wink

https://sites.google.com/site/stingrayslistofrotorcraft/tsheten-dorji-rotorwash-deflection-aircraft

Kryptid · Member

I meant that the tail would probably be more efficient if it were actually shaped like an airfoil relative to the direction of the rotor downwash. That way you'd have less boundary layer seperation than if the tail were simply a flat plate canted at an angle. The "elevator" could control the amount of deflection and therefore the amount of force produced by the tail in yaw.

tsheten8 · Veteran Member - Level 2

Wow,that's a fascinating idea...thanks for the attachment sir...

Regards
Tsheten8

Kryptid · Member

You're quite welcome!

tsheten8 · Veteran Member - Level 2

I had been doing some research on the feasibility of completely replacing tail rotor on single main rotor helicopters with anti-torque surfaces..there's a research carried out by CAL in the late 60s..according to the research,to completely replace a tail rotor in all flight regimes,the surface area of the anti-torque surfaes should be around 35% of the main rotor disc area..such a huge area of surface mounted on the tail is impractical...but I thought what if the surface comprises of multiple number of small surfaces(the summation of whose areas yielding upto 35% of main rotor disc area) functioning as a unit to counteract the main rotor torque???..it was stated and explained the research that the direction of induced velocity becomes parallel to the disc plane with increasing forward flight..to overcome this problem,we could use vertical stabilizers mounted on the end of the anti-torque surface like it's being used on the NOTAR helicopter...

regards,
Tsheten

Hell(i)Master · Veteran Member - Level 1

Interesting!!! Can You give me a link to this research?

This picture is from 1999 russian magazine, they stated that tail area must be 17...21% of main rotor area. This system could suffer from wind gusts and may have problems in ground effect.

Hell(i)Master · Veteran Member - Level 1

Russians took it one step further.

tsheten8 · Veteran Member - Level 2

hmmm...those are only pictures i believe..did anything get built?..

Hell(i)Master · Veteran Member - Level 1

They experimented with models, there are some calculations and descriptions, but it is all in Russian. Maybe it is uderstedable with Google translater. Just let Me know if somone is interested.

tsheten8 · Veteran Member - Level 2

Umm..I would like to have it friend..))..I have a Russian friend..I'll get help from him..

kindest regards

tsheten8 · Veteran Member - Level 2

Well,with my gyro project on the way I was also thinking on improving the current design of the helicopter anti torque configuration..I am thinking what if we could also use sideways lift producing cycloidal rotors,along with deflection panels, placed at the end of the tail boom and let it rotate under the downwash wind in a hover..in forward flight,the fins on the cycloidal rotors will be pre-oriented in such a way that the craft's relative wind will rotate the rotors..

This principle is something similar to the arrow feathers of a composite bow..as the arrow is released by an archer it rotates ,by virtue of air flowing past its feathers,to gain gyroscopic stability but also gets deflected slightly sideways..this proves the presence of a sideways acting lift on the arrow..

Any comments would be appreciated..

regards
tsheten8

Eolo · New User

Tsheten8,
I was searching info on a similar idea on the web when I found your post. I truly believe in this concept. Have you been able to find out more on this principle? Any idea why this simple concept has not been used ?
Around 30% of the rotor surface does not seem so impracticle when using multiple surfaces?
The only similar concept I have seen is an RC "flying ball" - single rotor, but very large anti torque surfaces relative to the rotor surface:
www.youtube.com/watch
Regards,
Eolo

Eolo · New User

An other interesting forum on this topic:

http://www.eng-tips.com/viewthread.cfm?qid=137831

Eolo

tsheten8 · Veteran Member - Level 2

Hmm...thanks for the links friend))..the korean spherical flying machine is interesting..and I think the concept of donwash deflection or impingement is not used in the real world maybe because things have not been tested and refined on full size machines..like you say, I deeply believe in this concept too..and I have not researched further on this concept..but I have been refining it myself..like uaing cycloidal rotors along with deflecting surfaces..

Any other idea from you would be greatly appreciated...

Kindest regards