[ARC5] [Milsurplus] ARB Canvas Cover

[Taigh Ramey]

A couple of observations:

Please don't think that these aircraft were all sealed up and water tight because they were not. The gun turrets leaked like crazy and most if not all installations had rain gutters and drain tubes. The PB4Y-2 had two Martin 250CE turrets/leakers on the top of the fuselage not far from the radios

From my research and experience freshly sealed glazing was often not water tight either. I have heard from WWII C-47 pilots that it was normal to carry extra charts to cover their legs during heavy rain as there was a waterfall coming from the top of the windshield. Zinc chromate tape was the typical sealant for glass at the time and it is definitely temperature sensitive.

Sliding canopies on all of the Fighter, Torpedo, Scout and Patrol aircraft will easily leak especially when the water was helped by 150+ knots of wind.

Speaking of warm and cozy I would wager that the covers could very well have been used to keep the heat inside and even throughout the radio. There are many examples of electrically heated covers used in aircraft primarily on the sensitive equipment such as bombsights and their associated autopilot components. The need was to help maintain functioning tolerances in the electro-mechanical components. Even machine guns had electrical and in some cases small gas fired heaters to keep them from freezing up at altitude or simply the cold climates encountered in theatre. Imagine the lessons learned in the Aleutian campaign?

These aircraft operated at extreme temperatures and environments so maybe it was a combination of keeping the water out and it's subsequent freezing at altitude?

WWII equipment had to pass testing for temp extremes and there was a spec for this. The Army Air Force had painted green or yellow dots on gear that meant it would function in specified temp ranges. Maybe the cover was used to help meet this spec? I have seen these dots on everything from electronics to brakes and hydraulic components mostly Army gear though. 

Somewhere I have a reference for the temp ranges for the different colors. As I recall the yellow was -40c to 100c but I am not too certain of this.

Taigh



Sent from my iPad

On Mar 2, 2013, at 10:47 AM, "J. Forster" <jfor at quikus.com> wrote:

> It seems they were not used in-flight or pulled pre-flight..
> Storage seems unlikely because of the exposed connectors.
> 
> What about land-mobile? For example, in the back of a Jeep or something?
> 
> -John
> 
> ===============
> 
> 
> 
> 
>> On Sat, Mar 2, 2013 at 11:34 AM, Mike Hanz <aaf-radio-1 at aafradio.org>
>> wrote:
>> 
>>> On 3/2/2013 11:10 AM, J. Forster wrote:
>>> 
>>>> The ARB cover I have here does not cover the connectors, electrical ot
>>>> spline.
>>> 
>>> True.  Nor did the ARMN photo mention covering the set (an ARC-5
>>> transmitter rack) with anything - just covering the connectors with Dow
>>> Corning Ignition Sealing Compound.  As I said, we're just speculating
>>> here.
>>> No real smoking gun to give you, sadly.
>> 
>> Then there's the RAX-1. Was recently flipping through the manual and saw
>> that it includes a set of 3 canvas covers, one for each set. The front is
>> totally open, and from the little I've learned and seen (primarily on the
>> aafradio pages, I admit), these receivers seem to have predominantly
>> been installed in the belly of much larger, land-based aircraft like the
>> PB4Y where they would be less-exposed, if at all.
>> 
>> One would guess that some covers were meant for storage and others for use
>> in flight. Perhaps the RAX-1 covers were meant to keep them warm and comfy
>> so they'd yield good info? (o:
>> 
>> ~ Todd,  KA1KAQ/4
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