REFLECTOR: A/C (was Re: GRT Displays overheating - Anyone elseseethis?)

[Alex Balic]

We just had an air show here at Denton, airport (TX) they had an A-10 on
display, it had a targeting pod attached under the starboard wing, in the
back of the pod, you could see it had a 134A air conditioning compressor and
radiator that must be used to keep the IR system cold. The compressor looked
like a fairly standard Nippondenso unit- hard to tell through the screen...

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brian Michalk
Sent: Wednesday, July 11, 2012 10:01 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: A/C (was Re: GRT Displays overheating - Anyone
elseseethis?)

It was almost certainly bleed air.  For military purposes, it's light and
simple.

One of my previous jobs, we built electronics to fly in externally mounted
pods.  Heat rejection was our biggest enemy.  Keep power consumption low,
and it gets easier.  There's some crazy stuff out there with the extreme
being water cooled blade mounted VME or PCI cpu boards.  That stuff is
insanely expensive because the military is the only customer, and most
things are in quantity 1 to 10.  How about a 3" 
muffin fan that costs $400?  I thought we were getting ripped off, but after
seeing the testing that goes into it, and the performance parameters it
makes more sense.  Most times we had no choice either.  
The customer states the requirements and we had to engineer to them.

On 07/11/2012 09:42 AM, Mark Magee wrote:
> Funny the cabin A/C issue just won't die in the midst of this La Nina
heatwave. I was discussing the glass cockpit in an AH 64 Apache Longbow last
summer with the pilot displaying his bird at a local festival. The nacelles
on the port and starboard are all electronics for fire control, targeting
etc. etc. He allowed that one turbine was started and the A/C(s) were
started before the the other engine was started or the rotors clutched in.
This was purely to cool the cabins holding the electronics, and that on a
hot day it could take a few minutes before the electronics cabins were cool
enough for the electronics suites to begin powering up. All the while he and
the gunner would wait to engage the rotors because they weren't going
anywhere until all the electronics reported OPS NORMAL. At the core of it
all was multiple A/C units: I didn't cover with him if it was bleed air A/C
or what.
> I think cabin A/C is a good idea for many reasons, but as we are beginning
to see the old steam gauges could handle high cabin temps better than
current glass.
>

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