View Full Version : Servo Flap Rotor Control
I am curious as to why the servo flap rotor control system used in Kaman helicopters is not used by other helicopter manufacturers.
I have searched previous threads but not found much.
Would anyone care to share their views on this?
Dave_Jackson
6th Jan 2005, 19:54
From Aerospace Daily & Defense Report; ~ 06/11/2004
"Jointly managed by DARPA and the Army, the $500 million UCAR program is attempting to develop a highly autonomous unmanned combat helicopter ......
Teams led by Northrop Grumman and Lockheed Martin are competing in Phase II of the UCAR effort, working on preliminary designs for their respective systems. Northrop Grumman's UCAR is a tailless concept featuring twin intermeshing rotors to overcome torque, while Lockheed Martin is offering a compound helicopter featuring small wings and an auxiliary propulsion system."
DARPA was scheduled to choose in September a single team to move into Phase III and build two flying demonstrator aircraft.
It is reported that the Northrop Grumman's entrant utilizes servo-flaps. These flaps will work slightly differently from those of the Kaman helicopters. Sikorsky is involved in this project and Nick L. may be able to provide additional information.
Dave J.
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Edit
Opps! Forget the above.
From Aerospace Daily & Defense Report ~ 12/27/2004
DARPA Cancels Third Phase Of UCAR Program (http://www.aviationnow.com/avnow/news/channel_aerospacedaily_story.jsp?id=news/UCAR12274.xml)
NickLappos
6th Jan 2005, 20:06
On-blade control is the ideal, the old Kaman system was mechanically complex, but new technologies make it possible to do without linkages.
It is possible to do away with the swashplate and servos if the concept comes to fruition!
Dave, here is some undeserved salt in your wounds, I can across it this morning. Dr. Gordon Leishman on coax vs tandem vs single rotor:
http://www.enae.umd.edu/AGRC/Aero/merits.html
Dave_Jackson
7th Jan 2005, 01:24
Nick, thanks for mentioning the web page.
There has to be wound for the salt to hurt. :D
On the serious side, I agree that 'there's no free lunch'.
It would be very difficult for anyone to question Leishman's knowledge of rotor aerodynamics. However, his comparison between the single main rotor and twin main rotor configurations presents some points that are valid and some that are not.
You, nor I, nor anyone else reading this thread wants to dissect each of his points, but the following single comment may represent an overview. He says "To describe the relative merits of the single-rotor versus twin-rotor configurations, ....". He then discusses "tandems and coaxials" without any significant mention of latterly located twin main rotors.
The following might be of value, since Sikorsky has shown interest in Reverse Velocity Utilization for large transport requirements. Three of his main points are; download on the fuselage, twin-rotor interference, and blade vortex interaction. I humbly suggest that the interleaf (http://www.synchrolite.com/B263.html#Interleaving_Rotors) configuration with rotors turning outside-forward and cruising at high speed will greatly overcome these three concerns, while offering other strong advantages.
A little elaboration on this can be found at; Rotor Concept - Improved L/D Ratio - Reverse Velocity Utilization ~ Interleaf Configuration (http://www.synchrolite.com/1108.html#Interleaf)