|
Agreed, assuming proper execution, and
that's what Ross claims. But he still has the original cowl, with
both inlets and outlet(s), and the area around/above his new duct
inlet looks like a mess, with the original cowl exit hanging down
in front of where the boundary layer splitter should be.
He claims net zero cooling drag, but there are no hard numbers
showing fuel flow/speed/weight to give us some way to do a sanity
check.
Charlie
On 5/6/2015 11:34 AM, Bobby J. Hughes wrote:
Charlie,
If
you have a turbine type cowl then moving the inlets to the
belly duct should not increase the flat plate area. At
least that’s my theory.
Bobby
Hughes
N416AS
RV10 223 hrs
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
Sent: Wednesday, May 06, 2015 10:35 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Return to Flight
On 5/6/2015 8:01 AM, Tom Mann wrote:
Mind
you, my rotary is not flying yet and I have a Canard
design but I often wonder why the RV guys don’t
relocate the radiator and use a P-51 style scoop?
I’ve
seen many that have the radiator almost
perpendicular to the direction of the inflow.
I
would think that a radiator mounted just behind the
seats would give you the distance to properly expand
the air and recover the pressure more efficiently.
Just
thinking out loud ......
I agree, a perfect P-51 style setup would be better, but....
Ross Farnham in Canada has done it (sort of).
http://www.sdsefi.com/air9.html
http://www.sdsefi.com/rv17.htm
http://www.youtube.com/watch?v=QT8njoirTkU
http://www.youtube.com/watch?v=gPpWHvr1kJw
He won't publish hard numbers, but has vaguely hinted at a 6-8
knot speed gain over his old cooling system, which was pretty
convoluted (multiple air inlets/outlets in random places for
multiple random heat exchangers), so it was probably a net 0
gain over a well done under-cowl setup.
It's pretty complicated to run the plumbing, and since a
complete rotary installation that's built with careful
attention to weight can come in lighter than a Lyc (I put my
entire FWF on a scale: 310 lbs, dry), moving the heat
exchangers aft is likely to adversely affect the CG. Ross got
away with it because he's running a turbo Subaru, which is
pretty heavy. The P-51 rad is partially submerged in the
fuselage. Submerging the rad in the aft fuselage sounds great,
but even if you can deal with the CG issues, with a metal
fuselage you have to be very careful what & where you cut
to get the air in & out. And the scoop itself is extra
weight (the cowl is already there for the outside of the
'scoop').
Water cooled engines beg for an airframe designed around them,
just as air cooled engines have planes designed around them.
Charlie
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
|