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>Some factory clarification here would be welcome.
Regards, Bill Hogarty<
Good request but regardless of the factory answer it is worth
understanding--
If you rotate to a pitch attitude and then wait till the aircraft flies off
you are asking for trouble. Here's just one of many reasons why:
Let's assume you like to rotate to a pitch attitude of 8 degrees and wait
till the aircraft flies off. This may work nicely at low density altitude
airports and results in the desired climb IAS. However if you rotate to
the 8 degrees attitude at a high density altitude airport, your AOA may be
so high (and close to the critical AOA -- stall-- ) that the aircraft will
take longer to accelerate and fly out of ground effect. In this scenario,
even light turbulence or vortices could spell disaster! This is called
taking off way behind the power curve, speed stability curve, reverse
command or as I like to call it "ON THE DARK SIDE."
When I taught mountain flying, it was an emphasis item to rotate to a lower
pitch attitude on T/O at high density altitude airports as compared to the
lower density altitude airports we usually depart. We always want to
rotate to the same AOA which does not equate to the same pitch attitude.
The folks like Bill, Brent and others, that think in terms of a Vr that
increases with increasing GWs and a rotation attitude that lowers with
increasing density altitudes are the safer flyers. Early rotations are a
high risk maneuver and are used on soft field T/Os only. This issue is a
technical one, but I do go over it briefly in our "Flying safe with AOA"
forums given at Oshkosh and Sun'n Fun.
There are as many T/O techniques as there are instructiors, but only a few
are based on sound aerodynamics. I'm very aware of the poor T/O techniques
taught by one former Lancair IV approved instructor. If your technique
includes the early rotation, as fun as it is, keep in mind it is a higher
risk maneuver with no advantages excepting soft field departures.
James B. Frantz
Proprietary Software Systems, Inc.
www.angle-of-attack.com
LFrantz@compuserve.com
(952) 474-4154
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