Guest Maximinious Posted November 15, 2010 Report Share Posted November 15, 2010 (edited) ... Edited July 30, 2011 by Maximinious 1 Quote Link to comment Share on other sites More sharing options...
AStarB3 Posted November 15, 2010 Report Share Posted November 15, 2010 2) If you read carefully it is 8degrees of pitch twist. This means that from the rotor mast if you measured the pitch angle of the rotor right at the hub and then measured the pitch angel at the tip of the rotor there would be a difference of -8 degreed. This is because the rotor is moving slower at the center of the disk so a greater pitch angle is required Quote Link to comment Share on other sites More sharing options...
Shaun Posted November 15, 2010 Report Share Posted November 15, 2010 I like the term wash-out rather then negative pitch. Quote Link to comment Share on other sites More sharing options...
AeronauticallyInclined Posted November 15, 2010 Report Share Posted November 15, 2010 I have two questions about the R-22 that I am hoping someone can answer. 1.)Question about rotor droop: When you get rotor droop (at high density altitude), do the the blades actually droop down? I thought that because of the reduction in centrifugal force the blades would start to flex up. I was under the impression that the term "rotor droop" was referring to the rotor rpms "drooping down" when there isn't enough power to sustain the amount of pitch you are pulling. No, the blades won't droop down, "rotor droop" like you said refers to drop in rotor rpm. As a matter of fact when experiencing rotor droop (reduction in RPM) in order to provide the same amount of lift the blades would actually cone up more. Quote Link to comment Share on other sites More sharing options...
NorCalHeliKid Posted November 15, 2010 Report Share Posted November 15, 2010 No, the blades won't droop down, "rotor droop" like you said refers to drop in rotor rpm. As a matter of fact when experiencing rotor droop (reduction in RPM) in order to provide the same amount of lift the blades would actually cone up more. What he said, but Ill add this Army Def: Rotor Droop is defined as the decrease in engine RPM which occurs between the time a demand for power is made and the time power is delivered. Droop can occur during normal flight maneuvers when a rapid demand for power is made.(ie rapid pedal input or collective increase) Quote Link to comment Share on other sites More sharing options...
Eric Hunt Posted November 16, 2010 Report Share Posted November 16, 2010 Terminology, Bloggs... Remember there is Transient Droop (immediately during a power demand), Static Droop (what you get after the power has stabilised) and the droop (sag) of the blades when shut down, when they rest against the Droop Stops. Cornfusing....... Quote Link to comment Share on other sites More sharing options...
Guest Maximinious Posted November 16, 2010 Report Share Posted November 16, 2010 (edited) ... Edited July 30, 2011 by Maximinious Quote Link to comment Share on other sites More sharing options...
Eric Hunt Posted November 17, 2010 Report Share Posted November 17, 2010 Except in some Navy helicopters, the blade is still developing positive lift with collective fully down. Yes, the hub has positive pitch, and the tip may be a little negative, but overall the blade has positive lift, so it cones up. Watch the R22 blades go from sagging down to being level as they spin up - partly through centrifugal effects, partly through lift developed. Some Navy helos have the ability to go into negative pitch, when permitted to by the weight-on-wheels switch, and push themselves down onto the heaving deck. It can only be done on the ground, and cannot be done in flight. Quote Link to comment Share on other sites More sharing options...
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