Crab,
Thank you for your reply to my post. Here's a few of my thoughts which may clarify one or two things for you:
Jellycopter - most helicopter horizontal stabilisers are upside down wings designed to produce a downward force to keep the fuselage attitude more level in forward flight - the direction the air is coming from eg from the front or the back is immaterial and a tailwind would not produce more downforce than a headwind, especially at the low airspeeds we are talking about in the hover.
You're absolutely right about the upside down wing bit, but when you state "the direction the air is coming from eg from the front or the back is immaterial" you are sir, quite wrong! It's the angle of attack of the aerofoil which dictates how much lift (or down force) it produces. You'll note that many fixed geometry horizontal stabs are rigged at a negative incidence angle ('Rigger's Angle') to assist in their main role....to keep the fuselage at the optimum attitude for cruise flight (not necessarily level by the way). These stabilisers can be cambered (eg. Bell 206) to improve their effeciency and stalling characteristics at the generally low airspeeds and diverse alphas they operate at. Such a Riggers Angle can, and often does, produce the opposite effect to what is normally required when subjected to a tail wind. Hence the B206 et al running out of aft cyclic with moderate tail-winds due to undemanded nose-down pitching moments generated by the horizontal 'de-stabiliser' (?). When the stab lifts the tail up, it must be producing lift; ergo, it must reduce the hover power, albeit small and arguably immeasurable.
The strake on the Sea King is designed to disrupt lift on the port side of the tail boom and only affects pedal position and thus hover power in a crosswind - the old girl used to run out of left pedal in a right crosswind because the tail boom was creating lift horizontally to the left and more left pedal was needed to counteract it.
Not being qualified on the SK, I must accept what you say regarding the purpose of the strake. Nonetheless, does the strake not also have a secondary effect of generally reducing hover power in the same way it does on the Squirrel B2/B3?
I am particularly amused that so many pilots with a fraction of the knowledge and experience of Nick Lappos insist on rubbishing his explanations just because they go against what they were taught at flight school. Just because your instructor knew how to teach you to hover doesn't qualify him/her as a TP - they are regurgitating the same lessons and opinions that were taught to them - Nick is trying to highlight that knowledge of helicopter aerodynamics has moved on and the old wives tales from the past are mainly fallacies.
Crab. You and I were both taught at Shawbury, and we both probably taught there too (Don't know your identity so don't know for sure). Although the P of F served it's purpose, you and I both know it left many gaping holes. Notwithstanding this, I find your 'amusement' at posts disagreeing with Nick the 'Test Pilot' to be interesting. I have the greatest respect for Nick, and for many of his ilk and Rotorheads would be a much poorer place without his (and indeed your own) contributions. Neverthless, he's human and even TPs have been known to make mistakes once in a while. (Not that I have disagreed with anything he's posted on this thread by the way!) To trust a TP implicitly would be like beleiving the Eurocopter TPs when they insist the Gazelle can't get Fenestron Stall/LTE/Yaw Divergence when, after bitter experience, many of us know it can. Therefore the Robbo jocks who see 2" MP rise when they hover downwind aren't necessarily making it up just because Nick reckons it shouldn't be so. When instructing on the R22, I've seen the same effects myself, but on an equal number of occasions, I also saw the MAP drop. Why...... That's the whole point of this thread. I've just highlighted some potential contributary factors.
J
Edited for p@~s poor spellign