Why Gun Tractor Shape

[chrisgrove]

OK, I'm only a modeller (but with 30 years in the army behind me). Everything I have read says that the sloping back to the various gun tractors were designed to make it easier to decontaminate the vehicles in the case (which seemed quite likely at times) of chemical warfare. Once chemical warfare seemed to be less likely, square back FATs were produced.

In addition, a limber beside the gun was a lot less conspicuous than a gun tractor. If the gun line came under enemy fire, it would seem safer for the gun tractor to be some distance away at the wagon lines and thus less likely to be targetted.
Chris

[Lang]

Chris

My two cents worth is the sloping back/chemical warfare theory does not hold water. The back only makes up about a third of the horizontal surface area and a flat roof would be just as easy to wash down.

Guns can only be inconspicuous until the first shot is fired then they are immediately the subject of counter battery fire. A relatively large percentage of all artillery resources are solely dedicated to this task. If the object is aerial surveillance camouflage before firing then the trucks will certainly be in the hiding plan.

The truck "wagon line" will always be very close (less than 100 metres usually from the guns) if they are not co-located. The driver is a gun-number and must run back from parking the truck when they come into action. If it is open country you may as well leave the trucks behind the guns. If there are a few trees it is wise to take advantage of them.

All the crew gear is also carried in the truck and they must have their living arrangements very close to the guns to come into action within a couple of minutes day or night.

None of this seems to have any bearing on the sloping back design. The 18 pounder ring theory still gets my vote from those offered so far.

Lang

[Owen Evans]

Thought these photos of supposedly prototype Morris and Guy Ant gun tractors might be of interest. Also, the CDSW gun tractor here: http://www.mapleleafup.net/forums/showthread.php?t=6333 also has the sloping back...sort of.

What's the framework on the back of the Guy GT 'prototype'?

Owen.

[Lang]

After 300 years of towing guns maybe the gunners wanted to keep looking at something that resembled a horse's a.....?

[David Herbert]

Just to throw something else into the discussion, quite a lot of modern Humvees have a sloping back. There is no practical reason for it that I know of but at least early on that was the default rear body design.

The two 'prototypes' in post #18 were obviously only intended to be tractors to directly replace horses. The fact that they could easily be used to carry stuff seems to have not yet been noticed.

David

[rob love]

It's almost like they took the guy ant prototype and simply made it bigger. It looks like the rear deck has brackets that are holding legs similar to that used on mortar tripods. I can't place what artillery equipment used those legs.

Re the HHMWVs, they sloping back is on the "slantback" hardtop only. I suspect the slantback was simply so the gunner in the turret ring had an unobstructed view to the rear if he wanted it, or that the hatchback simply gave a little protected cargo room than a flat cargo bed. Kind of the same reason they made car trunks into hatchbacks.

[Ed Landstrom]

To confirm the theory that the sloping back on a Humvee was to give the gunner an unrestricted view to the rear, I was told the same thing by a Humvee driver, so it was what they were being told in training. Specifically, it was designed so that the gunner could fire over the rear with the vehicle parked nose-down on the reverse slope of a berm, using the berm for cover, with the rear of the vehicle facing the enemy. It seems like a rather infrequent use to base a vehicle design on, unless American forward bases are designed with protective berms that would fit this use.

[Hanno Spoelstra]

Originally Posted by Lang

None of this seems to have any bearing on the sloping back design. The 18 pounder ring theory still gets my vote from those offered so far.

I think this subject is being beaten to death. The sloping back was designed to accommodate the gun's mounting base. Period.

Note: when the design and use of field guns evolved, the design and manufacture of Field Artillery Tractors apparently had to catch up later. Also, don't forget that it is often more effective to keep manufacturing a proven design, rather than disrupt mass production of an otherwise adequate vehicle. This is what helped to win the war: while the Germans were designing new tanks, the North American arsenal of democracy mass-produced an adequate medium tank.

HTH,
Hanno

[David Herbert]

A Sherman has a sloping back too.....

David

[Lynn Eades]

....And you know why, David. A completely different reason to the FAT, Hummer etc.