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
!!..........................<:)