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Post Info TOPIC: New anti-torque concept


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Date: Feb 8, 2012
New anti-torque concept
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Hi everybody,I have here a new concept I developed myself a long time back,when I was in high school, for the elimination of tail rotor in a single main rotor helicopter and replacing it with a vertically mounted lift producing surface...The advantage of this setup is that we've all the power,excluding the losses due to transmission,going to the main rotor...

Currently,I am working on this design concept but haven't concluded anything yet..Hope that it will prove applicable in the real world..One thing I can say for sure is that it'll work in a hover mode where we'll have high velocity downwash from the main rotor acting on the surface to produce anti-torque effect...As the heli gradually advances into forward flight,we'll have to depend on the increased mass of air,rather than high velocity downwash, for the torque effect to sustain...One major problem facing this concept is that in forward flight,there will be two different types of airflow acting on the surface...One will be the downwash from the main rotor acting perpendicular to the leading edge of the surface and the other the aircraft relative wind acting parallel to it...I've attached a drawing of the concept in this post...

Give me some ideas...

Regards

Tsheten8



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Date: Feb 8, 2012
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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...



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Date: Feb 9, 2012
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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

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Date: Feb 9, 2012
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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.

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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...

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Date: Feb 15, 2012
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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

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Date: Mar 5, 2012
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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.......

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Date: Mar 5, 2012
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Tp be honest this seems more approprtiate in Builders section, that is if you plan to build concept one day.



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Veteran Member - Level 2

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Date: Mar 5, 2012
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Oh!....so I see Stingray.....and yes,I am going to materialize this concept one day....

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Date: Mar 13, 2012
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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

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Date: Mar 17, 2012
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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

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Date: Mar 17, 2012
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"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.



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Date: Mar 20, 2012
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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

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Date: Mar 22, 2012
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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

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Date: Mar 23, 2012
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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

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Date: Mar 23, 2012
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wink

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



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Member

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Date: Mar 23, 2012
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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.



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Date: Mar 23, 2012
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Wow,that's a fascinating idea...thanks for the attachment sir...

Regards
Tsheten8

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You're quite welcome!

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Date: Feb 6, 2013
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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


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Date: Feb 18, 2013
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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.



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Date: Apr 27, 2013
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Russians took it one step further.



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Date: Apr 30, 2013
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hmmm...those are only pictures i believe..did anything get built?..

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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.

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

kindest regards

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Date: Oct 9, 2013
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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

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Date: Dec 29, 2013
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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

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Date: Dec 29, 2013
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An other interesting forum on this topic:

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

 

Eolo



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Date: Feb 14, 2014
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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

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