blkhawk16 Posted July 24, 2007 Report Share Posted July 24, 2007 I was wandering why there is a difference between helicopters in the placement of the pitch horn on main rotor blades. I know for the R-22 it is 78 degrees. Gyroscopic precession takes place 90 degrees later, so why are pitch horns not placed at 90 dgrees from the blade. Does it have to do with the number of blades? Maybe control input response time? Any input would be appreciated Thank-you,blkhawk16 Quote Link to comment Share on other sites More sharing options...
joker Posted July 24, 2007 Report Share Posted July 24, 2007 blkhawk16, Good observation. The 90-degrees we are taught is a theoretical value for gyroscopic precession. In reality, due to those things you mentioned the 'phase angle' adjustment (Gamma) means that for different helicopters the pitch horns will be offset from 90-degrees. Yes, the R22 is 78; the S76 its 57 I believe. Other factors which will vary this value must be then RPM, blade chord, aircraft speed etc..etc..\ Joker Quote Link to comment Share on other sites More sharing options...
FauxZ Posted July 24, 2007 Report Share Posted July 24, 2007 The frequency of the blades flapping also plays a role, correct? As in, we have to allow time for the blade to fly to it's new position. Now we know the offset for rotation is 78°, but what is the delta 3 angle for the MR on the R22? Quote Link to comment Share on other sites More sharing options...
joker Posted July 24, 2007 Report Share Posted July 24, 2007 18 degrees isn't it? Quote Link to comment Share on other sites More sharing options...
FauxZ Posted July 25, 2007 Report Share Posted July 25, 2007 18 degrees isn't it? That sounds right, but I don't have the reference with me. Quote Link to comment Share on other sites More sharing options...
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