Military History | How To Make War | Wars Around the World Rules of Use How to Behave on an Internet Forum
Fighters, Bombers and Recon Discussion Board
   Return to Topic Page
Subject: Coaxial Rotors? Advantages v. Disadvantages
kc_scout    4/7/2011 2:30:24 AM
I've been reading up on coaxial rotor designs lately, and I was wondering if anyone had any opinions on it? A few of the advantages that I've come across include greater stability and the design is less vulnerable to combat damage, given there's no long drive shaft running to the tail rotor. It is, however, more mechanically complex. I'm just an enthusiast so my knowledge of aerodynamics is extremely limited. But how do coaxial designs fair in high altitude environments like Afghanistan? Should/would the U.S. ever adopt such a design? Perhaps for the CSAR-X requirement?
 
Quote    Reply

Show Only Poster Name and Title     Newest to Oldest
AThousandYoung       4/7/2011 12:47:51 PM
All I know is that the Russians seem to like them.
 
Quote    Reply

violentnuke       4/12/2011 7:01:24 PM
Coax are heavy and do not take advantage of the long tail to counter torque as a useful aerodynamic feature - the way the Apache does it, not needing a tail rotor power above 90 knots.
They have, however, as a result, very quick yaw rates since the cockpit can be resized at will with little angular momentum.
 
The coax is thus a much more modular concept, and that is why the Russians can easily modify their Hokum/shark series to any kind of navy or transport craft.
 
For high velocity I would use a NOTAR system, use retreating blade for thrust, advancing blades for lift (indian swim style), and place the NOTAR thruster assymetricaly behind the retreating blades for lift and additional thrust.
 
Quote    Reply

gf0012-aust       4/12/2011 9:24:10 PM

All I know is that the Russians seem to like them.

they're more or less the experts on co-ax rotors.

technically I'd think that the way that they manage torque via contras makes them better for hover missions such as ASW and precision insertion.
 
Quote    Reply

45-Shooter       4/13/2011 12:58:14 AM

Coax are heavy and do not take advantage of the long tail to counter torque as a useful aerodynamic feature - the way the Apache does it, not needing a tail rotor power above 90 knots.


They have, however, as a result, very quick yaw rates since the cockpit can be resized at will with little angular momentum.

 

The coax is thus a much more modular concept, and that is why the Russians can easily modify their Hokum/shark series to any kind of navy or transport craft.

 

For high velocity I would use a NOTAR system, use retreating blade for thrust, advancing blades for lift (indian swim style), and place the NOTAR thruster assymetricaly behind the retreating blades for lift and additional thrust.

The big push for co-axial rotors is two fold! First high speed! The faster you go, the less lift is produced by the retreating blade until asymmetric lift overwhelms the control forces. The second aspect is size reduction for ship board use. Other wise CR rotors are losers! They never quite make up in extra lift what they give away in extra weight!
 
Quote    Reply



 Latest
 News 		  Most
 Read 		  Most
 Commented		  Hot
 Topics