Machine Gun Cooling Oil?

[Ducked]

This came up in another thread. Allegedly the Long Range Desert Group used hypoid oil in the cooling jackets of their Vickers machine guns, to conserve water.

http://www.lrdg.de/vehicles4.htm

Assuming this is true, why hypoid? Its obviously not wear-related.

I think the normal water-cooling relies mostly on the latent heat of vaporisation of the water in sustained fire, since the water boils and is bled off to a condenser.

Presumably this isn't an option using oil, and so they are relying on the specific heat.

Does hypoid gear oil have a higher specific heat than engine oil?

Specific heat capacity MAY have been adequate because the LRDG didn't expect to need sustained fire, and perhaps didn't have enough ammunition for it, bullets being heavy things.

But in that case they wouldn't need much water either. Hmm...Not sure I believe it.

 

[Jetronic]

I think they used hypoid oil because that's what they had... oil for the rear differentials.

 

[HerrStig]

We won't mention what the Marines did in WWII when the water cooled Brownings ran dry.

 

[Jetronic]

when you gotta go, you gotta go?

 

[user52165]

Originally Posted By: HerrStig
We won't mention what the Marines did in WWII when the water cooled Brownings ran dry.


That's nothing. When I was at Ft. Benning, part of the training was to do this on a soldier who had severe over heating. Never saw it happen but it was in the manual if no other liquid was available.

 

[Ducked]

Originally Posted By: Jetronic
I think they used hypoid oil because that's what they had... oil for the rear differentials.


Of course, but they also had motor oil, petrol, water and urine, all in limited supply.

Petrol would probably work fine. It'd be a bit dangerous, but then machine guns are dangerous. I always used to cut myself on the Bren.

Water and urine, of course, would work best, though urine might cause corrosion.

Doesn't seem that oil would work very well at all, and I'm wondering why they chose it over water, and why they chose hypoid over motor oil.

(I've seen it claimed somewhere that British troops used the Vickers to make tea, so the water would still be available for drinking in extremis. This was probably a tactical limitation, urine-wise, though.)

 

[Jetronic]

if you don't drink much, you don't urinate much. so you could run out of urine, which would mean you needed to top off with water, or drink more.

the hypoid oil was likely surplus, ie they had an abundance. and it wouldn't need topping off for the entire trip so no need to carry extra.

 

[Ducked]

Originally Posted By: Jetronic
if you don't drink much, you don't urinate much. so you could run out of urine, which would mean you needed to top off with water, or drink more.

the hypoid oil was likely surplus, ie they had an abundance. and it wouldn't need topping off for the entire trip so no need to carry extra.


You aren't going to run out of anything because of the gun, unless you fire it.

If you have to fire it, you probably want it to work. I doubt oil is effective for sustained firing, and I guess it'd coke up, overheat, and possibly explode.

If you aren't indulging in sustained firing, which for the LRDG is likely, then you aren't going to consume much water so you may as well use it, since, as the designed coolant, it'll work best, and at base you'll have an abundance.

So this fix doesn't make much sense to me and I wonder if its true, though without experience I can't be sure that it isn't.

 

[Shannow]

It would be better than nothing at stopping the barrel getting too hot and distorting.

But the water provided a latent heat process that the Aussie diggers then ran a hose into a kero can and used as a condenser to recycle the water.

 

[MolaKule]

If I had a machine gun that needed fluid cooling this is what I would use:

http://www.schaefferoil.com/281s-heat-transfer-fluid.html

 

[HerrStig]

Originally Posted By: user52165
Originally Posted By: HerrStig
We won't mention what the Marines did in WWII when the water cooled Brownings ran dry.


That's nothing. When I was at Ft. Benning, part of the training was to do this on a soldier who had severe over heating. Never saw it happen but it was in the manual if no other liquid was available.
I don't know many Marines who would miss an opportunity to do that to a doggy.

 

[Ducked]

Originally Posted By: MolaKule
If I had a machine gun that needed fluid cooling this is what I would use:

http://www.schaefferoil.com/281s-heat-transfer-fluid.html


Thermally stable, but low evaporation, so no latent heat cooling, so still inferior to water.

And the 1941 QM store might not have had any in stock.

 

[Shannow]

Yep, the big thing was boiling around the barrel to remove vast quantities of heat versus straight convection.

 

[BULLDOG221]

We urinated on a 4.2" mortar tube when we had a misfire and the tube was hot.

 

[bubbatime]

Maybe since they were fighting in the desert, and didn't want to die of thirst, they conserved the water for drinking, and used oil instead to cool off the guns. I cant blame them.