Browning .50 Aircraft gun barrel cooling jackets

[Rick Lowe]

Hi All

I am experiencing some confusion over these.

We all know and love (or we should! ) the standard Aircraft-style 'fifty', with the full-length, perforated jacket.
As a result of knowing what they 'should' look like, I have for decades been moaning about the 'orrible broomhandles that the various kit makers give us for their aircraft turrets.

Just recently I was completing a 1/72 A-20G, and spotted that the turret guns of the example in the Squadron book do NOT have perforations... they are a solid tube.

Thinking about it, I realised I have seen examples of planes such as the A-26 and B-25H where the nose gun jackets are also solid.

Does anyone know of the reasons for this? Was it to do with the altitude/theatre they were serving in? Or the position of the gun on the aircraft in question?
Or was it like the Sherman Turret Pistol Port, and depended on the date of manufacture (I have seen late ground-mount fifties that have slots in the cooling jacket, not round holes)?

Can anyone enlighten this rather dazed and confused 'fifty spotter'?

Cheers

Rick

[rickshaw]

There are three types of cooling on the Browning .50cal HMG. 

The water-cooled jacket - primarily used on AA weapons, which required a higher ROF and which necessitated better cooling of the barrel to prevent rounds cooking off in the chamber.   I've never seen one of these on an aircraft but they were common on tripods and on naval craft.

The perforated cooling jacket - primarily used where a flow of air through the jacket cooled the barrel.  Lower ROF than the previous one and the perforated jacket was primarily designed to protect users' hands from coming into contact with the hot barrel.  It could also, in the case of aircraft allow cool air easy access to the weapon as well as hot air to exit.

The plain, heavy barrel - primarily used on ground mounts and vehicles where a lower ROF was considered acceptable.  Relied primarily on the thickness of the barrel walls to absorb and radiate heat, out to the surrounding air.   A similar but actually lighter barrel more than likely would have been used in the pictures you saw, relying on the flow of air over the barrel in flight to cool the barrel quickly.

In each case, it depended upon how the weapon was to be employed, as to which cooling system was employed.  Behind the barrel, all the weapons were essentially identical (although the feed systems might be different as well).

The Browning .50cal was a good weapon.  Solid, reliable but not necessarily a great performer.  It's ROF was lower than comparable weapons.  Its round was slightly more powerful than German and Japanese rounds of comparable calibre.  Its muzzle velocity IIRC was also higher.   The Soviet 12.7mm guns OTOH were star performers, particularly the ones used in aircraft just before and during WWII.   High ROF, high muzzle velocities and very reliable.

[Rick Lowe]

Thanks, I am aware of all three varieties you mentioned.  
These, however, look to be the standard aircraft flexible/turret gun, with the only difference between them and ones having the 'proper', fully-perforated cooling jacket being the complete absence of cooling holes.

... hang on half a mo' though, I have had another d'oh! thought - maybe they were DUMMIES, in a mock-up turret, asa prototype/proof of concept thingy... that sounds more like it...

Rick, hanging head and doing the Walk Of Shame...

[Aircav]

Hi, I found this pic on the net and haven't been able to find out anymore yet but I do have a couple of old Gun books and I'll have a look through them at the weekend for you.
Steve

ps. just found a M2HB forum, they should be able to help
http://www.m2hb.net/m2phpBB3/index.php

[Logan Hartke]

Yeah, the actual ones used had the perforated jackets.  Here's a shot from my trip this year.



Cheers,

Logan

[CANSO]

Just recently I was completing a 1/72 A-20G, and spotted that the turret guns of the example in the Squadron book do NOT have perforations...

Is this the photo you mentioned above?

It obviously shows the national insignia with the red border, used for a brief period (June-August/September 1943). The a/c has no visible code letters (usually placed on both sides of the insignia). Could this be some test/experimental a/c?
It's interesting, but the barrels appear to me rather thick - compare with the same Martin-turret (on a Canadian Lanc), having guns with cooling jackets.

[Rick Lowe]

Yeah, I think that's what it is - a mockup gun in a prototype turret... d'oh!
So I'm not going (that) crazy after all... some consolation at least.

Cheers all

Rick