TAIL ROTORS

Thread View: sci.aeronautics

3 messages

[T] Back to Threads [V] Tree View [G] Group Articles

3 total messages Started by Trevor German Tue, 15 Dec 1992 14:19

#619

Author: Trevor German
Date: Tue, 15 Dec 1992 14:19

38 lines
2175 bytes

	I am an engineer and think I understand all the reasons why helos
	have tail rotors, however, it seems to me that they may not be 
	as nessecary as they appear. 

	I remember seeing a real low speed film of a dragonfly in flight
	and watching with fascination how the beast uses a pair or weighted
	pendulums behind the wings that swing in anti-phase to the main wings
	counteracting the up and down forces on the critters body caused by 
	the wing beats. Why can't a similar thing be done in helocopters.


	The problem, as I understand it, is that the torque of the engine 
	driving the rotor is balanced by the tail rotor pushing the other
	way. By adjusting the pitch of this rotor the balance is modified
	to swing the tail in either direction.  

	My question is why not put the torque adjusting in line with the
	main rotor. Granted there are counter-rotating rotor machines but
	these are complicated and expensive. Why not have a higher RPM 
	ducted vertical fan driven through a gearbox on the main shaft 
	pumping air down under the craft. The design of the fan should be
	done in a way that makes it very viscous, that is, a lot of torque
	required to move air.  The speed of the fan would 
	obviosly be greater than that of the main rotor. The pitch of the 
	fan would again be adjustable, or maybe just a damper in the airflow
	could suffice.

	This may have already been tried, or maybe I am missing something
	fundemental, but I am intrested in any comments or knowledge of
	similar schemes that have been tried.



--
       >|  "Only average people            | Trevor J German BSc    |<
       >|        never make mistakes."     | NCR, Waterloo, Ontario |<
       >| tjgerman@53iss6.Waterloo.NCR.COM | Canada.                |<

Re: TAIL ROTORS

#620

Author: Teresa Kline
Date: Tue, 15 Dec 1992 18:09

21 lines
1397 bytes

In article <10299@ncrwat.Waterloo.NCR.COM>, tjgerman@53iss6.Waterloo.NCR.COM (Trevor German) writes...
> 
>       Why not have a higher RPM 
>	ducted vertical fan driven through a gearbox on the main shaft 
>	pumping air down under the craft. The design of the fan should be
>	done in a way that makes it very viscous, that is, a lot of torque
>	required to move air.  The speed of the fan would 
>	obviosly be greater than that of the main rotor. The pitch of the 
>	fan would again be adjustable, or maybe just a damper in the airflow
>	could suffice.
> 
>	This may have already been tried, or maybe I am missing something
>	fundemental, but I am intrested in any comments or knowledge of
>	similar schemes that have been tried.
> 

It has been tried.  See any AvWeek or similar journal and look for the 
NOTAR (no tail rotor).
-- Teresa

		Life -- just for the FUN of it!!!!

Re: TAIL ROTORS

#642

Author: Peter Gale
Date: Thu, 17 Dec 1992 04:32

25 lines
1502 bytes

tjgerman@53iss6.Waterloo.NCR.COM (Trevor German) writes:


>	I am an engineer and think I understand all the reasons why helos
>	have tail rotors, however, it seems to me that they may not be 
>	as nessecary as they appear. 

	Try the Sikorsky ABC aircraft, Kaman's, Russian machines,
	MDHC's MDX Explorer (1st flight this week?)...

>	these are complicated and expensive. Why not have a higher RPM 
>	ducted vertical fan driven through a gearbox on the main shaft 
>	pumping air down under the craft. The design of the fan should be
>	done in a way that makes it very viscous, that is, a lot of torque
>	required to move air.  

	In otherwords a power plant just to generate drag?...

>	This may have already been tried, or maybe I am missing something
	Then again maybe just hold the aircraft up with a skyhook. :-)
--
Peter Gale                        | Ph: 61 2 330-1686    | Sydney
Senior Systems Programmer         | gale@socs.uts.edu.au | Australia
School of Computing Sciences      | Fax: 61 2 330-1807   | ---------
University of Technology, Sydney  | --------------------------------

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads