Lu WROTE: "The reason I am starting to make sense is summed up in the story of the young man that thought his father was so stupid, and when the boy reached 21 years of age, he was amazed at how smart his father got in six years."
- NONSENSE you are just learning, without anyone realising how little you knew...
- The Pilots job in setting a Cyclic dissymetry to counter aerodynamic dissymetries to ensure equal lift around the disc ... you have clearly just understood!
Shame you are taking so long to understand what you mean by Gyroscopic Precession:
GP: More pitch on ONE side will cause the blades of that side to flap (a process) up, the process of flapping up causes the Angle of Attack to be reduced. Result: the 'lift' stays the same but only because the blade is now RISING - this RISING (or Flapping Up) will finnish at the END of the half where there was extra pitch, ie. APPROXIMATELY 90degrees after point of MAX Pitch.
It is very convienient not to have to explain this, so the term 'Gyroscopic Precession' is used since it BLINDLY predicts approximately the same behaviour.
You must try to understand this - otherwise you miss the true 'elegance' of the helicopter.
Lu:"How do you reconcile the differences in aerodynamic and physical laws as taught in the US and the UK?" - Simplification for Americans... of course!
On reading Lu more carefully it is apparent that his use of English is often what causes the misunderstandings.
Allow me to illustrate Lu's ENGLISH being 90Deg 'out of phase':
Lu: "When you push the cyclic forward on most Bell helicopters the swashplate will tilt down at the 12:00 position with the blades disposed over the 3:00 and 9:00 positions. With the blade in this position the pitch horns are at the 12:00 and 6:00 positions. That means that the blades have the maximum pitch change relative to their collective pitch angles. The advancing blade will have less pitch and the retreating blade has more pitch and some "unknown force" will cause the blade disc"
In this paragraph the phrase: "blades have the maximum pitch change" implies that the rate of change of pitch is a max - whereas I'm sure he means the pitch (ammount, quantity or value) is a Maximum (or minimum). Pitch Change implies a rate, the max rate of which obviously occurs at 12&6 o'clock.
I'm sure CRAB is just getting HIS TERMINOLOGY 90deg out from our understanding in the same way, since he does at least appear to UNDERSTAND the process:
A blade at 3 has it's Pitch Link at 12 (approx), therefore to run min blade pitch at 3 the swash plate must be 'tilted down' at 12. The Max Rate of Pitch Change occurrs at 12(blade at 12, pitch link at 9) requiring upward Force on swash plate at 9 hence righthand stick force(not movement, just force) requirement. Right CRAB?
Lu: I guess the simplest way to get accross the concept you call GP is to think of the pitch variations flying the blades to a new plane of rotation - does that help?
(and/or likewise ...preventing changes in plane of rotation)
Lu you are clearly still 'screwed up' over things like 'Blow Back' - to us this is more violent version of 'Flap Back' - do you use that term? Retreating blade stall and Diss of Lift - similar ? - well yes ... but only in-as-much as that IS how a rotor system works!
Lu:"The culprit (are you ready for this?) is gyroscopic precession." - no! Again: A Falling blade (flappING down) will be low at the END of the half in which it is FALLING. .. getting it yet?
CRAB (and other mil-bible die hards)... just a side question : Do the military still teach (wrongly) that recirculation at cliffs results in attitude change TOWARDS the cliff? (worth a (see)new topic(s)... I think)
[This message has been edited by JoePilot (edited 21 January 2001).]