Mike,

    Not a dumb question - but, part of the answer may be as you suggested.
There is a lot of work to installing a rotary power plant and cowl work is
one more thing.  Plus, the GM cores used behind the standard duct openings
have proven inexpensive and that they work just fine.  Also, I suspect some
folks just want to retain the original cowl profile.

Powersport had an arrangement similar to what you suggest - took them a long
while to overcome cooling problems with it.  Don't know what the problem was
(Powersport has never been very forthcoming about any problems), but I think
it was placing their rad too close to the firewall.    Also there is a
person who sells such a cowl for the RV ( I think he originally made them
for PowerSport).

There is no reason such an arrangement could not be made to work, one
individual in Arizona also uses a similar arrangement (rad below the engine)
and  had cooling problems (he may have them sorted out by now)  - but, then
he is in Arizona which would stress the capability of any cooling system
{:>).  I do not know of anyone's example to follow, so perhaps you will be
the first.

Ed

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From: "Wynn, Mike" <mike.wynn@spectra-physics.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, June 16, 2004 1:43 AM
Subject: [FlyRotary] Cooling airflow


> Dear All,
>
> I have been reading with interest for a long time and wanted to ask what
> maybe a dumb question...
>
> Everywhere I have looked people use the standard `Lyc.' type cowls with
> cheek openings and place the A/C `radiators' either side of the PSRU
behind
> suitable ducts.  I assume this is because it is easier to adapt the
existing
> rather than to build a new cowl.  However, would it not allow a straighter
> and less draggy cooling setup if one were to design a cowl with a single
> opening under the prop (a bit like, but much smaller than, a P40) and then
> use a single duct to expand the area into the rads (placed under the
> engine), and then continue straight out under the cockpit - perhaps with
> some augmented airflow from the exhaust???  Surely this would allow a more
> efficient airflow and enable smaller intake area and avoid the air having
to
> fight its way round the engine bay to get out?
>
> Is it just the fiberglass work people are avoiding, is it the avoidance of
> the unknown (surely Rusty will have a go here???)
> What am I missing?
>
> Thanks
> Mike
>
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