Mailing List flyrotary@lancaironline.net Message #9730
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: New Scoop
Date: Wed, 14 Jul 2004 14:43:22 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Sorry to harp on this Steve. I just have a feeling that you're working
hard
to get the temps lower than they really need to be. If you want minimum
drag
at cruise, then the temps SHOULD be marginal on a hot day take off and
climb. So... get the gear up and back off the throttle till you get in
cooler air at cruise speeds. If necessary give it a rest half way up, or
use
the technique of doing a long approach to cool off before climbing that
someone described. If it'll cool ok at full power at cruise height, then
you're in good shape. My 2c.

John


Steve, I have to agree with John on his main point.  Any cooling system is
going to be a compromise.  If you design and tailored your cooling system
for cooling in a steep climb on a hot day, you will have excessive cooling
capacity at cruise (read - more cooling drag) than is necessary.  On the
other hand if you do optimize for cooling at cruise (min cooling drag) which
is the way a lot of Canard types do as that is one of the reasons for their
choice of aircraft type - high cruise speed, then you will be somewhat short
of cooling capacity needed for take-off/climb.  Things like cowl flaps can
help in some cases, but like everything else with an aircraft has benefits
and draw backs - its all a flying compromise.

So as suggested you can moderate power and/or  airspeed during the climb
portion to get through that heat gauntlet and then be set up for lowest
cooling drag at cruise.

Also, keep in mind, you are probably flying in the hottest time of the year,
so if it will cool adequately now, it will be fine the rest of the time.

However, if that does not fit with your comfort zone, then you will simple
need to keep plugging away until you get the conditions you are comfortable
with.

Ed  Anderson


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