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Whats the plan for exit air... If I remember right you had retro
style armpits AND naca's. twice the needed inlet area. One armpit
went to the intake. The other armpit? to the oil cooler? exiting
into the cowl?
Where is your intercooler airflow coming from (you did a turbo,
right)... where is it exiting to? (inside the cowl, right?)... Your
NACA's.. they are going to a plenum in front of the firewall... that
houses the radiators.. and clearly exits into the cowled space. Does
that NACA fed plenum have separation from the armpit scoops or is it
one big common plenum? If so, ram air in the armpit is likely
running out the top through the naca's...
All this air is coming into the cowl and how is it leaving? When I
was involved in your build I had thought of using a short tailpipe
and having an augmenter-style exhaust on that side to help suck air
out, venturi style. I even bought a twin cessna augmenter tube off
ebay to serve as a template for making one on your plane. Its 6"
diameter and a couple feet long, and planned on cutting it down to
size if we went that way. If your exhaust is blocking most of the
passenger side cowl exit, then EVERYTHING has to try and cram though
the pilot side cowl opening.
Thats two NACA's and one armpit (the armpit not dedicated to intake
air) trying to go out one single hole. I suspect that your in-cowl
area is one giant high pressure zone. Simply putting a belly scoop
on the bottom wont fix that..
If I'm wrong please prove it, please put pics up of your install..
cowled and not.. and let some of these guys give some feed back...
You may not like the idea of cowl flaps but it may be necessary... A
simper idea would just to put some exit vents into the cowl (they
sell vented plates at the boat shop.. rivet em in, add microbubble
to fair the edges, paint.. voila.. Very low drag elegant solution to
depressurize the cowl... two of em on the upper sides of the upper
cowl might be a SIMPLE and quick fix (the upper side of the plane is
a low pressure zone compared to the bottom)... Use physics to help
you out.
When dealing with airflow the EXIT is just as important if not more
important as the intake... The belly scoop might work... but... if
it doesn't address the underlying problem (and I suspect there IS
one) then you will still have cooling problems.
Dave S
Dave
On 5/13/2012 12:34 PM, Chris Barber wrote:
Not very well. I was using the factory NACA. I had hoped,
unwisely that it would push enough air through the heat
exchangers to do the job. Alas, no joy. I wasn't surprised but I
wanted to give it a shot. I even modified the NACA's with some
baffles but still no go.
I am currently doing as I likely should have already done and
placing the rad and oil cooler under the engine with a big ol'
ram scoop. Depending on testing I will make the scoop smaller if
warranted.
I moved the a/c condenser and turbo intercooler to the front
of the engine (where the rad/oil cooler was) to be fed from the
top NACA. Those items are not as critical and I suspect the
NACA's will handle their need.
We shall see.
Sent from my iPhone 4
Chris,
How does
cooling air get to your heat exchangers? Do you
have any pictures of your install?
B2
From:
Rotary motors in
aircraft
[mailto:flyrotary@lancaironline.net]
On Behalf Of Chris Barber
Sent:
Saturday, May 05, 2012 11:04 AM
To: Rotary motors in aircraft
Subject:
[FlyRotary] Re: Twin Velocity
I want to but I am
having some serious cooling issues on high speed
taxi, up to over 250 degrees for a few minutes
(yikes). I tried something with modified NACA's
based on Velocity Inc reducing cooling issues when
they changed from armpit scoops to top NACA's,
however, that is not working so I am going to a
more direct ram air with a P-51 scoop. I hope to
start the conversion later today. The process may
have intimidated me years ago, but, hey,
the Gov'ment says I be a "Repairman" ;-)
Chris
Are you
ready to take advantage of that transition
training? When is the first flight? :>)
Bill B
From:
Rotary motors in
aircraft
[mailto:flyrotary@lancaironline.net]
On
Behalf Of Chris Barber
Sent:
Saturday, May 05, 2012 10:06 AM
To:
Rotary motors in
aircraft
Subject:
[FlyRotary] Re: Twin Velocity
It's
a kewl plane. I got to see it when I was
at the factory last month for transition
training.
Chris
Sent from my iPhone 4
This thing is just begging for two 13B
or Renesis Rotary engines
!!..........................<:)
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