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

Mark Magee edjonesbrady at gmail.com
Wed Jul 11 10:09:56 CDT 2012


Sorry all hit Send inadvertently... Trying again:
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 Velo cabin A/C is a good idea for many reasons, as we are beginning to see the old steam gauges (punintended) could handle high cabin temps better than current glass panels.
I pulled apart a small roll around 4,000 BTU A/C that pulls 4 amps on the AC I Used camping with the kids. I think 4000 BTU's of A/C would marginally cool an XL cabin on a 100F OAT day. The good part is the whole unit can be run on an inexpensive 1000W sine wave inverter that factoring in 8% efficiency loss it would still only pull about 50 amps on the 12V. I'm hoping a second alternator, possibly a  supplenator would fit the bill and double as a back up alternator. As well I might install some 110V outlets for use in flight after the A/C was shut down in the cool air.
I think the whole arrangement with alternator might add 12 lbs. 
Chris I'll see you in Houston and look at yours: I really would like my bird to have A/C if it makes sense.


Mark B. Magee
Sent from IPhone 4

On Jul 11, 2012, at 8:20 AM, Chris Barber <cbarber at texasattorney.net> wrote:

> Thanks Scott,
> 
> Yeah, I know.  Blaine used my plane to get a general idea for the layouts. I think I am the one who put Blaine in touch with Velocity years ago.  I know I made a call or two. Blaine Streeter, Pres of Seamech, has become a close friend of mine over the last several years.  He is a great guy and has a passion for aviation.  We have helped each other work on our planes.  I have his RV cowling in my hangar now doing some finishing after we modified it for the Subaru.  Funny, RV guys don't like working with fiberglass much;-)
> 
> I spent a week vacation at Hawker/Beech back in March assisting him finalize some production line procedures on the Bonanza and Baron installs.  Ok, my input was minor but I am a pretty good gopher.  Yes, I am such a geek at times that this is how I spent a week of vacation...cold, wet Kansas. :-)  I also got to fly his Bonanza up there and around Houston to prepare for my transitional training.  BTW, the transitional training may be the best $1500 (ok, plus meals, rental and Capt Hirams) that I have spent on my project...uh, check that, my plane.  It really helped me to feel a "bit less nervous" for first flight.
> 
> Chris
> 
> ________________________________________
> From: reflector-bounces at tvbf.org[reflector-bounces at tvbf.org] on behalf of Scott Baker [scottb33333 at gmail.com]
> Sent: Wednesday, July 11, 2012 8:07 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: A/C (was Re: GRT Displays overheating - Anyone elseseethis?)
> 
> Chris,
> The Seamech company developed several air conditioning systems for Velocity XL models; one with a Lycoming IO-540 and the other with a TCM IO-550.
> Scott B.
> 
> Scott Baker
> 
> On Jul 11, 2012, at 8:53 AM, Chris Barber <cbarber at texasattorney.net> wrote:
> 
>> I just sent a text to the owner of Seamech asking for some detail.  I know he has considered sales to individuals but has not focused on it.  My plane was kinda his prototype for a Velocity/Canard.  He is building a RV-7 with a Soob with his A/C
>> 
>> Chris
>> 
>> ________________________________________
>> From: reflector-bounces at tvbf.org [reflector-bounces at tvbf.org] on behalf of Lawrence Epstein [ljepstein at hotmail.com]
>> Sent: Wednesday, July 11, 2012 6:27 AM
>> To: Velocity Aircraft Owners and Builders list
>> Subject: REFLECTOR: A/C (was Re: GRT Displays overheating - Anyone else seethis?)
>> 
>> Can you give specs/cost info on your A/C (the Seamech website is light on details).
>> 
>> Larry E.
>> 
>> On Jul 9, 2012, at 9:51 AM, Chris Barber <cbarber at texasattorney.net> wrote:
>> 
>>> Interesting you mention the A/C Mark. My first three flights were without A/C....well, on the third I turned it on while taxiing back to the hangar.  The guy who supplied me with the A/C (owner of SeaMech Environmental Systems...provider of A/C to Beechcraft, Cirrus, Cessna) is wanting me to use the A/C now that I think I have my cooling under control and I think I will on my next flight.  The certified models he installs are rated for use at takeoff.  I am still just flying around the airport.
>>> 
>>> It is ridiculously hot...but of course it is Houston in July...what would I expect.  As I have stated, if I am gonna fly in the heat, I need to test in the heat.
>>> 
>>> Chris Barber
>>> Phase One Testing
>>> 
>>> ________________________________________
>>> From: reflector-bounces at tvbf.org [reflector-bounces at tvbf.org] on behalf of Mark Magee [edjonesbrady at gmail.com]
>>> Sent: Sunday, July 08, 2012 10:45 PM
>>> To: Brett Ferrell; Velocity Aircraft Owners and Builders list
>>> Cc: reflector
>>> Subject: Re: REFLECTOR: GRT Displays overheating - Anyone else see this?
>>> 
>>> Hi Brett,
>>> You guys all laughed at me and my longings toward cabin A/C... We closed out that thread. I agree with GRT on the vents except I'd consider some 12V pc power supply fans, one port one starboard, blowing up on the windscreen. This would double as winter defogger/deicer. With the doors open until after run-up you should be getting a fresh flow of 100F air on a hotter day. If you can get aloft into cooler air I'd think you'd have a shot at keeping the Glass out of over temp. Pretty simple fix, two holesaw cuts on your glare shield and mount the fans and grab 12V from same circuit powering the GRT's: those fans pull very little power.
>>> Frankly I'd even consider laying a Blue Ice pack or two below my Glass displays secured somehow for summer work until this confounded La Nina weather pattern subsides.
>>> Or install A/C: I'm game!
>>> My $.02 USD.
>>> 
>>> Mark B. Magee
>>> N34XL
>>> Sent from IPhone 4
>>> 
>>> On Jul 8, 2012, at 9:36 PM, "Brett Ferrell" <reflector at velocityxl.com> wrote:
>>> 
>>>> We've had quite a string of hot weather here in SW Ohio as of late, and on the last couple of flights we've had issues with our GRT HX screens overheating and shutting down in flight.  We've got backup dial gauges, but needless to say, it's disappointing when you lose the fancy readouts, and though we've been planning to fly to Airventure we will likely won't if we can't quickly find a solution to the issue.  Has anyone else seen this behavior?  If so, how did you resolve it?
>>>> 
>>>> GRT tell me that the screens should run 'about 30 degrees' above ambient.  They will shut down at 160 F, and you can see the internal temperature by going to setup menu (Display Maint, Analog Input page).  It's been right at 100 F here for the last few days, and I can confirm that on the ground they warm right up to 130.  We went around the pattern and in less than two passes they were shutting down!  I went to the setup page, and sure enough, they were reporting in the mid 150s.
>>>> 
>>>> GRT believes that if I add vents to my glaresheild the issue will resolve itself, but I have already tried a large (68 cfm) computer fan aimed at the back of the displays, which only relieved about 1 degree F of temperature, and tried routing cooling air from the nose fresh air vent to the back of the displays to no effect (the screens still shutdown in flight).  I believe my situation is unique because I mounted a second oil cooler in the nose for winter recirculating air usage (rather than  cold outside air), and have checked this cooler is, in fact, getting quite hot.  On my last flight it was over 200 F even though the one on the nose NACA was below 180, so I think this cooler is just filling the nose area with hot air.  Net, I'm going to pull that cooler, and at some point put vents in the glaresheild, but that's a fair amount of effort the way I have it mounted.
>>>> 
>>>> Brett
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>> 
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> 
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Mark B. Magee
Sent from IPhone 4
> 
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