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From: mmallory@netcom.com (Mark Mallory)
Subject: Re: g forces and trim (again)
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Date: Sun, 10 Jan 1999 05:11:50 GMT
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Mackfly (mackfly@aol.com) wrote:
: Nope---prop blast and power on / off has little to do with it.  Try it in a
: sailplane.   Is it not a matter of the planes speed?  The horz. tail download
: does not come from prop blast.  You don't think that T tail is flying without a
: download on it do you?

The download on a T-tail is the same as on a conventional tail.  But the
conventional tail, being in the prop blast, sees an INCREASED downforce
with increasing prop blast; this must be compensated for by retrimming. 
The retrimming is not necessary with a T-tail because (for a given
airspeed) the airflow doesn't change with changes in power. 

This is actually one of the few *nice* characteristics of the Tomahawk: if 
it's trimmed to climb with full power at 70 knots, if the power is pulled 
back to idle without changing trim it will DESCEND at nearly 70 kts as 
well.  On the other hand, a '152 will descend power-off 15-20 kts 
faster than it's full-power climb speed with no trim change.

