Why Gun Tractor Shape

[Mike Cecil]

Lang,

To be fair, the AWM were not the originator of the furphy about the shape being for gas decontamination, but made the error of quoting an otherwise reputable source without checking or thinking about it. The origin, as far as I can make out, was as indicated by this post in another MLU thread:

"Reference to the design shape is contained in a Mechanisation Board minute featured in Ventham and Fletcher’s Moving the Guns : the Mechanisation of the Royal Artillery, 1854-1939, p81...."

And I agree with you: just because an individual is in the employ of the AWM (or any other military oriented museum) does not mean he or she has a sound knowledge of military matters or history.

Mike

[Hanno Spoelstra]

Originally Posted by Mike Cecil

The origin, as far as I can make out, was as indicated by this post in another MLU thread:

"Reference to the design shape is contained in a Mechanisation Board minute featured in Ventham and Fletcher’s Moving the Guns : the Mechanisation of the Royal Artillery, 1854-1939, p81...."

Here is a cross link to the relevant posting in the thread AWM acquisition?.

Thanks for bringing that source up again, Mike.

HTH,
Hanno

[rob love]

Reading that link, I would say it is a mis-interpretation by the author. Here I have copied the relevant part:

A clue to the origin of the curious "beetle shape of the guy ant, and other quads, is contained in the Mechanization Board report for 1939 which states:
"To permit decontamination, an all metal body to the Chief Superintendent of Design's was fitted, involving an increase of weight of 17cwts"

Thus, the characteristic shape of these vehicles was born of the need to be able to wash down the vehicles to rid them of chemical contamination......

Now if you take away the author's interpretation of that, here is the actual line from the Mechanization board report:

"To permit decontamination, an all metal body to the Chief Superintendent of Design's was fitted, involving an increase of weight of 17cwts"

My un-learned view of that line was that they previously had wood in the Chief Superintendent's design of the body, or that the Chief Superintendent of Design has changed the design to get rid of the wood. Note that in the photo of an early Guy Ant on the previous page, the body was made of wood. Wood, being porous, does not lend itself well to decontamination, so they instead changed the design to all metal, which made the bodies heavier.

The author of that book, I believe, has made a mistake in his interpretation, and that interpretation has been blindly repeated and accepted for fact. Using the word "thus" in his leap does not make it fact.

[Hanno Spoelstra]

Originally Posted by rob love

Reading that link, I would say it is a mis-interpretation by the author. Here I have copied the relevant part:

Now if you take away the author's interpretation of that, here is the actual line from the Mechanization board report:

"To permit decontamination, an all metal body to the Chief Superintendent of Design's was fitted, involving an increase of weight of 17cwts"

My un-learned view of that line was that they previously had wood in the Chief Superintendent's design of the body, or that the Chief Superintendent of Design has changed the design to get rid of the wood. Note that in the photo of an early Guy Ant on the previous page, the body was made of wood. Wood, being porous, does not lend itself well to decontamination, so they instead changed the design to all metal, which made the bodies heavier.

The author of that book, I believe, has made a mistake in his interpretation, and that interpretation has been blindly repeated and accepted for fact. Using the word "thus" in his leap does not make it fact.

Rob, I fully agree with your line of reasoning!

H.

[rob love]

Further to my last, note the excerpt mentions an increase of weight of 17cwt (roughly 1904 pounds in today's measurement). Sloping the back of a box would reduce weight, not increase it. Changing a wooden box to steel , however, could well increase the weight. Thus , ( ) this supports my reading of the sentence as to mean it was referring to the conversion of the previous wood design over to an all-metal design.

[Bruce Parker (RIP)]

Originally Posted by rob love

Further to my last, note the excerpt mentions an increase of weight of 17cwt (roughly 1904 pounds in today's measurement). Sloping the back of a box would reduce weight, not increase it. Changing a wooden box to steel , however, could well increase the weight. Thus , ( ) this supports my reading of the sentence as to mean it was referring to the conversion of the previous wood design over to an all-metal design.

Rob, I think you've just added forensic linguist to you resume.

[Mike Cecil]

Well done Rob, I think your interpretation is spot on: a mis-reading of the original intent of the quote.

I cannot say every fact in my books is 100% correct, either (or any technical history book, for that matter): blunders like that by authors are bound to occur, but we all do our best to bring other enthusiasts the fruits of our original research. I did a book review for SMH recently about the Aust WW1 Centennial History, and felt I had to point out a significant error by a well-respected historian, so it can happen to the best researchers/authors as well.

Thanks Hanno - my ability with cross linking etc is non-existent!

Mike

[Phil Waterman]

Hi All


Personally, I think the sloped rear of the Gun Tractor was one of the following reason:

• The original designer was the father of the designer who thought tail fins would look good on cars.

• The original designer was look for a design which would have an Iconic shape to form the desires of a generation of young boys, so they would love CMPs

• The reason is now lost in the mists of time, we should have thought to ask this at the CMP Conference back in 1984.

Cheers Phil

[Mike Cecil]

Phil,

You didn't add: the designer just wanted to keep generations of vehicle enthusiasts puzzling over/debating the matter!!

Mike

[Bruce Parker (RIP)]

Originally Posted by Mike Cecil

Phil,

You didn't add: the designer just wanted to keep generations of vehicle enthusiasts puzzling over/debating the matter!!

Mike

You're all missing the obvious answer. "Shortest on the left, tallest on the right...size". After that the tallest gun crew members sit up front and shortest sit in the back.

It's funny how you read things. The description for Chev HUW's is that they had steel panels in the rear windows. For years I thought this meant steel panels in the rear door windows which puzzled me as I'd only ever seen glass. Then I figured out what they were talking about. It refers to having steel panels replace the upper rear body plastic windows on HUPs which is 100% correct.

[Tom Millward]

Hello guys,

Just a thought from a tank designer’s perspective, the sloping back would have given the gun No1 (the commander who stands out of the top hatch) a good view over the back of the gun tractor and allowed him to see the top of the limber, which may have helped the driver in maneuvering the awkward combination, particularly reversing. In the later Morris gun tractors the roof is squared off. Much better for stowing kit, but the rear view is obscured.

[Niels V]

I stumbled across this statement today will discussing Morris FAT designs:” while early Quads had the distinctive "beetle-back" shape, from 1944, the final model, the Mark 5, moved away from this characteristic shape as it was realised that it was too readily recognisable from the air, and therefore instantly indicated the position of an artillery unit. The Mark 5 was therefore given a more square body with a canvas-covered cargo space at the rear which made the vehicle resemble an ordinary cargo truck.”
From https://m.ww2db.com/vehicle_spec.php?q=O515 ,
Has anyone heard of this before

[m606paz]

Hi Niels
I have not heard that before, but it can be an answer as simple as it is effective. Sometimes we tend to complicate the answers.

[m606paz]

Originally Posted by rob love

They did. From the AEDB Design Records:"Reports from the field, however, indicated that the 7b2 -FAT did not full-fill all the requirements that had been anticipated, in that the payload was restricted, due to the design of the body. It was decided, therefore, to pilot a new FAT using the same chassis as heretofore, but considerably modifying the body. The sloping after deck was eliminated, and an all steel, open roof body, with superstructure and tarpaulin, was pilotted, the spare tire being housed in a compartment at the rear of the body. Considerably more stowage space was provided, particularly for ammunition which was for either the 17pdr or 25 pdr, role, and more room was available inside the body for the personal and their kits. This was the 7b3 body, and proved to be quite satisfactory."

A pity that the 7B3 body was never used during the war.

[rob love]

Originally Posted by m606paz

A pity that the 7B3 body was never used during the war.

The real pity is that they all seem to have been exported and few to none remain in Canada.

Also odd that being this late in the war, they used POW cans in the racks instead of the 5 gallon jerry-can.

[m606paz]

Hi Rob
It is true, that in Canada there is none.
Here in Argentina 2 survive in very good running condition and another 10 with many missing, according to my records.

Those racks are prepared to mount 3 pow or one Jerrycan. Very well designed.