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Old 07-08-2009, 12:05 PM   #26 (permalink)
Pinecone
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Quote:
Originally Posted by Finless View Post
OK so that makes sense now. Is it that they CANT do vertical and if not why? If they had negative available then I don't see why not?

Then I have to ask what happens in a real heli if you are in a 900 foot hover and the engine quits? To get forward momentum you would have to use energy from the rotor and change the angle of attach of the rotor to forward. In doing so wont you dump head speed without having negative to compensate?

Bob
You dump collective to maintain rotor RPM, then push forward to get airspeed and then you enter a normal auto with forward motion.

From 900 feet, not a big deal.

Great fun from 200 feet or so. In an R-22 you want about 60 knots forward speed, IIRC. Basically the top of the H-V chart at 0 airspeed gives you just enough altitude to get the needed airspeed and to flare for the landing. But the H-V chart is based on a "normal" pilot with a 2 second reaction time.

But a real helo cannot do a straight vertical auto, from above about 15 feet (for a helicopter with good rotor energy). An R-22 will hit pretty hard with a 15 foot hovering auto.
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