Landships II

Well the designers of the British Mks I to VII managed to get the best of both worlds as the curve along the bottom of the rhomboid gives exactly the same ground contact as the big wheel project would have. This gave exactly the same trench crossing capability and turning circle as the big wheel would have without creating an enormous target for enemy artillery. When this curve was lost (as in the Tadpole Tail and the Mk V* and some designs by other countries) then steering became much more difficult and considerable strain was put on the frame when turning (too much for the Tadpole for example). The upward curve at the front is based on the rearward curve of the Killen Strait track and gives a  good ability to climb over things. All in all for its specific purpose as a 'shelled area' tank the rhomboid was a good if not the best solution. (Its worth noting that in the final weeks of WW1 when fighting had moved away from the heavily cratered and trenched areas the St Chamond actual became reasonably effective as an assault weapon). When the going is hard and relatively flat the rhomboid looses some of its advantages and in fact a wheeled vehicle could do better than tracks of any design. It wouldn't have to be big wheel though. However in the majority of wartime conditions the going is arely hard and flat.

The most telling point against the big wheel is its size and thus vulnerability to enemy fire. A big wheel machine is also much heavier than the equivalent tracked vehicle that can cross similar trenches. Also, how do you transport a big wheel machine (or, worse, a whole fleet of them) to the Front? You could drive them, but most roads would have been too small, and ditto for bridges.

Centurion, I'm afraid that I have to disagree with you about the track profile of Mother being that of a big wheel. This claim, which I have seen made in various places (even Glanfield), is, as far as I am aware, a canard. There is simply no need for it to follow the curvature of any particular wheel (and I've seen the size of the wheel it supposedly emulates quoted as anything from 16 feet to 45 feet to 60 feet). I don't have any primary sources, but here are a couple of secondary sources that state that Wilson himself denied the myth:

It was Wilson who first drew out the shape of a slightly deformed rhomboid but both men [Wilson & Tritton] spotted at once the possibility that they had found what they were seeking... It is commonly said, even by Stern, that the underside was deliberately made as the arc of a 16 foot [sic] wheel. Wilson says flatly that this is nonsense. First mention of it comes in Williams-Ellis' 'The Tank Corps' published in 1919. Wilson was very cross, for professional engineers would see the absurdity of the proposition and blame him. As the book was quasi-official, he wrote a protest 'but without result'. (Smithers: A New Excalibur, p.55)

Wilson had seen that in order to meet the required trench-crossing performance, the track frames would have to be much larger than the hull they supported. He found that a sort of rhomboidal lozenge shape suited best... Various claims have since been put forward concerning the inspiration of this idea, the most pervasive being that the shape was derived from the curvature of a 60 foot wheel, a suggestion which, it should be noted, was always rejected by Wilson himself. In actual fact, the lower run of the track is not a continuous curve, but rather a subtle mixture of shallow curves and short straights, an evolutionary extension of the Little Willie track design. (David Fletcher & Dick Harley: 'British Tanks of the Great War', Tankette, Vol.16, no.5, p.3)

However, I completely agree with your other comments. It must be remembered that the first British tanks were designed for very specific conditions, i.e. the shell-cratered mud of the Western Front. Features such as, for example, the lack of suspension were accepted as a trade-off against designing tracks and frames that could withstand crossing trenches and climbing high parapets without the risk of the tracks shedding (a perennial problem with the commercial tracks of the day). Take the tanks away from that environment and they don't fare so well, but this is not a flaw as they weren't designed for other environments.

-- Edited by Roger Todd at 13:58, 2005-12-30

I'm sorry for misinterpreting what you said, Centurion. However, I still feel that what you did write is tantamount to saying the same thing anyway, in that you're saying the shape of the track frames was related to a big wheel in some fashion, when I don't believe that to have been the case as I've never read anything that would corroborate it. I'd be happy to be proven wrong (and learn a new thing) if you've got some evidence handy, though.

Well, Stern, admirable organiser he may have been, wasn't an engineer, whereas Wilson was (and a brilliant one at that). In technical matters I'd therefore tend to regard Wilson as more reliable. Williams-Ellis's book may have been semi-official, but Wilson disputed that too. The others you mention merely quote Williams-Ellis. All in all, from what I've seen so far, I'd tend to go with Wilson and disregard an explicit connection with big wheels.

The track solution was best for the time and ever since, otherwise we'd have seen big wheel machines in action. As it is, other than the odd early experiment such as the Tsar Tank (conspicuous by its failure) and aberrant one-offs such as the odd machine the Germans built in WW2 for clearing mines (can't recall the name), no-one has actually pursued the concept. Once the need for trench-crossers passed and the high rhomboids became obsolete, a low profile was the order of the day, and that's one thing you will never get with big wheels.

As for the FT-17, the big wheel at the front is merely a large idler (and it only looks so large because it's on a small machine), it doesn't function as a 'big wheel' in any way. On the whole, it's just a development of the Holt or Bullock type suspension.

Gentlemen I seek further enlightenment. The following is an extract from Tanks and other Armoured Fighting Vehicles 1900-1918 by B T White.

In this machine, known as ‘Big Willie’, the famous lozenge shaped profile with tracks running round the top of the hull was introduced for the first time. It was said that the lower curve of the track was derived from a section of the perimeter of a big wheel of a diameter sufficient to cross a trench width stipulated by the War Office. This data may conceivably have dictated the height of the front idler machine and the overall length of the machine, but the use of an upturned track profile for crossing obstacles has already been demonstrated in the Killen Strait tractor and in the design of the Nesfield Mc Fie landship, a model of which was submitted to the Admiralty in June 1915.

Can someone tell me what the Nesfield Mc Fie landship was?

The enclosed site is worth a look - some familiar big wheel stuff but also some new (at least to me)

http://grognard.com/zines/ga/g3a.txt

Interesting stuff, Centurion, thanks - and happy new year to you (and everyone!) too.

However, at the risk of sounding picky, only a small part of the arc of that circle coincides with a small part of the track frame profile. The argument now seems to be progressively weakening from 'the track frame followed the curvature of a 16 ft wheel' (not your words I know, Centurion, but nevertheless what others have written) to 'the track frame provided the same ground contact as a 16 ft wheel' to 'a small part of the track frame profile followed a small part of a 16 ft wheel arc'.

Below I provide a section of Dick Harley's drawing of Mother (from Tankette), which I believe to be very accurate, with an arc from a 16 ft circle superimposed. There is very little coincidence between the two. Given that the curve of Mother's track frame was not continuous but, rather, made up of several curves of different arcs in combination with straight lines, one could draw a circle of almost any size and find that part of the arc roughly coincides with a part of Mother's track frame. Such an exercise would be meaningless, however.

In my opinion (my opinion only, I must stress), it would take a great leap of faith, or imagination, to claim that there is any meaningful relationship between the 16 ft wheel and the track profile of Mother.

Others may, of course, disagree.

-- Edited by Roger Todd at 16:31, 2006-01-01

Nope, the wheel is definitely a scale 16 ft in relation to Mother in the drawing.

I take your point about the 'complex series of curves and straights' (which, IIRC, is how David Fletcher describes it, and he may be referring to the overall shape of the frames, not just the lower edge, although there it is clear there is more than one curve). And yes, clearly there were deliberate design decisions made in developing it. There could be various reasons, obvious ones being the parameters of width of trench and height of parapet to be crossed and scaled, but also, perhaps, including such matters as an assessment of how well the unsprung suspension would take to impacts against rough ground, I simply don't know for sure. As for difficulty in manufacture, I disagree. Surely once the initial drawings are made it's a simple matter to transfer the shapes to full-size templates? After all, warship designers had to contend with producing far more complex shapes in the form of hull plates with compound curves which had to fit tightly together, a vastly more intricate job than the flat plates involved in tank production.

I note your comment about the centre of the circle on your drawing - it appears to be directly over the point at which the 'foot' of the track frame begins to rise. But that still doesn't address the fact that only a tiny fraction of the wheel arc follows the track frame. I have to say that I have yet to be convinced!

As for the division of design responsibilities, I get the impression that Wilson designed the shape of the track frames, with Tritton more involved with track design (I haven't looked into engine and transmission issues as they're irrelevant to the issue at hand).

On the Lemon Wheel - from Glanfield, 'The Devil's Chariots': 'Lemon's Wheel and Rotating machine' produced disconcerting results. In October 1915 the Trench Warfare Department at the MoM (Ministry of Munitions) conducted experiments with a motorised rig which was designed to rotate a heavy wheel at up to 100mph before releasing it at a hostile trench along a short launching board. The spinning missile carrying a powerful explosive charge would hurtle into the enemy wire, through which Mr Lemon expected to flay a path for the following infantry, before it exploded above the trench. The experimental wheel duly tore through the wire before hitting the dummy trench parapet and taking off to land in a second trench 50yd beyond. Unfortunately the wire entanglement immediately sprang back, and as there was no means of controlling the detonation of the explosive, the project got no further.

It sounds a bit like the Grand Panjamdrum of the Second World War - and about as hazardous, too!

-- Edited by Roger Todd at 21:01, 2006-01-01

Centurion wrote:

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The reason why I'm wondering if Tritton played a part in the detailed design is the he was certainly something of a big wheel man and the fact that the points of congruity with the sixteen foot wheel are at the balancing point (probably the wrong term and not implying centre of gravity - rocking point perhaps) of the lower part of the frames might be his last gasp at continuing something of the old concept. It would certainly explain the various references to there being a vestigal wheel component in the design. Wilson may well have thought this inappropriate or not good engineering (he certainly didn't always agree with Tritton) hence his subsequent disavowel. It s all theory so far of course unless there is some contemporary material actually describing how the shape was actually arrived at.

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Actually, that is an interesting point, and you may well be onto something there.

Certainly, in respect to your other points, I would agree that it would make sense for Wilson to have concentrated on the transmission - as you say, he was an expert in the field. However, I suspect that in the early phase, his remit was wider. The transmission for Mother would have been child's play for him to design (it wasn't until sometime later that he designed the complex and highly regarded epicyclic transmission, I believe). Plus, the engine and main gearbox were the same as in Little Willie, with only the addition of another set of intermediate gears because of Mother's greater weight, another reason why designing the transmission would have taken Wilson no time at all. However, like you I have not seen any detailed breakdown of who did what. I will see if anything turns up in my researches.

Also, I agree that whenever possible, engineers will prefer straight lines to curves. However, if one looks at Little Willie, one is struck at how curved the lower part of the track frames are. Again, there is no single, simple curve. It seems to carry the 'fish belly' modifications to the Lincoln Machine's Bullock tracks a stage further, and Mother seems, to me, to be yet a further development of Little Willie's curved frames, carried to the nth degree, up and over.

Regarding Tritton's knighthood, Glanfield makes the interesting point that, quite apart from his important design involvement, Tritton voluntarily relinquished the £45 per engine commission he personally stood to earn as a result of a prewar agreement between Daimler and Foster's on sales to third parties of the 105hp engine (which Foster's had co-designed with Daimler). By the war's end, this would have been worth to Tritton alone £115,000 (at 1918 values)! Instead, it went to the Treasury. Maybe this played a part?

I know its WW2 but I thought you all might like to see that big wheels went on rolling

Actually its a mine destroyer.

Roger Todd wrote:

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I'd also add that if only for his work on devising the new tracks for Mother, Tritton deserved a knighthood. After all, she wouldn't have been possible without them. Anyway, on the subject of who did what, A J Smithers provides some useful information. It can be boiled down basically to this: Around August 1915, knowing that Lincoln Machine No 1/ Little Willie was totally unsuitable, Wilson suggested to Tritton 'a quasi-rhomboidal shape with tracks running outside'. On 24 August, Tritton submitted a sketch (either his or Wilson's is not clear; Wilson is said to have first sketched the 'deformed rhomboid', but as an engineer Tritton may very well have made his own) to d'Eyncourt who approved and told him to get on with it. However, it wasn't until 22 September that Stern received Tritton's telegram announcing successful tests of the new tracks, and work on designing Mother could begin in earnest. Wilson and Tritton retired to the White Hart in Lincoln to work on the designs, with all sketches and other sensitive material at the end of each day consigned to the fireplace. Wilson worked on the transmission which, contra my earlier, rather flippant, remarks, 'took much time' (Smithers). Due to the machine's height, a turret would have reduced stability. It was d'Eyncourt, the naval constructor, who provided a fittingly naval solution: sponsons. He made the suggestion to Stern, who made a rough sketch which he sent to Tritton who developed an exact drawing. So although Wilson first suggested, and sketched, the rhomboid, it was likely Tritton who did the detailed design, whilst Wilson concentrated on the engine and transmission.

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Isn't one of the great things about historical research that throwing light on one thing usually reaveals even more puzzles? There seems to be a number of apparent date inconsistencies in various accounts. One account  (supported by the commemorative plaque in the White Hart) states that Wilson "in conference with Tritton (in the White Hart) siezed a piece of hotel notepaper and said 'what about this?' The account then states that he drew a rhomboid. This is supposed to have taken place "in the month of September 1915"  This is recounted in John Foley's book The Boiler plate War. Foley was an old Tank Regiment  soldier (from 1936) and in his forward states that he interviewed Wilson about the events surounding the birth of the tank. However this doesn't make sense if Tritton had already come up with a Rhomboid design in August (unless there was a complete lack of communication between the two men which doesn't seem likely). Fosters booklet on the Tank published in 1920 states that design work on Big Willy started on 24th August 1915 and the wooden mockup was completed by 25th September, shipped to Wembley and shown the the landship Committee on the 29th September resulting in Stern writing to Fosters on the following day " I am instructed by the Director of Naval Construction to confirm his verbal orders to your Mr Tritton yesterday to carry out with all possible speed the construction of the machine as approved by him" This suggests that the general shape must have been decided before the track issue had been resolved. (Little Willy did not test the new tracks until  December 1915). Indeed given that the September trials of Little Willy in its No 1 Limcoln machine guise did not prove the unsuitability of the Bullock tracks until 19th September it must be clear that the Rhomboid preceded the  design of the new tracks and that Tritton must have been considering his track design even before the No 1 Lincoln was even completed. In general it suggests that quite a number of design decisions must have been taken before 22nd of September

The bulk of this is more in line with Smithers account than any other but none of the accounts is completely consistent. One wonders if Tritton had alrady had a number of ideas (especially relating to track) quite some time earlier but needed things such as the failure of the Bata tests and the No 1 Machine trials to give him the ammunition to support his own solution.

Roger Todd wrote:

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Marvellous! Rather like the German Minenraumer Eugene reminded me of earlier. Interesting that the only big wheelers built after the advent of the tank were built as mine clearers, I suspect because their huge mass makes them eminently suitable for the job. Incidentally, the Germans also built (or at least designed, I'm not sure how far they got) a prototype articulated big wheel minenraumer, of which this is a model: Shades of Tritton's machine...

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And here is the soviet successor to the Tsar tank.

http://www.tankmuseum.ru/images/fp1.jpg 

Another mine destroyer - it is a tricycle but you can't see the trail in this view. Incidentally the T 10 mine destroyer in my ealier posting also has a Tritton echo, before they put an M4 tank on top to drive and steer it  it was electrically driven by cables from a generator (in another tank) from a distance rather like one of Trittons big wheel proposals.

Roger Todd wrote:

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I have had a dig around in the Stern archives, and found a copy of Stern's 'Log Book of a Pioneer' with annotations by Walter Wilson himself (they are photocopies, as the originals are in an archive in Wales; Wilson was clearly serious about his notes, as they are extensive and typewritten). On page 31 of ‘Log Book of a Pioneer’, Stern claimed that in response to the War Office specifications for a machine capable of crossing a 5 foot trench and surmounting a 4 foot 6 inch parapet, Wilson and Tritton had said that such a performance would require a 60 foot wheel, and that the new machine upon which they commenced work had the profile, at the front, which was ‘more or less’ that of a 60 foot wheel.  Wilson has annotated the text thus (punctuation etc. are Wilson's): ‘On August 24th. Mr. Tritton submitted a sketch of this Machine to Mr. d’Eyncourt and he told Mr. Tritton to proceed with it at once. Mr. Tritton returned to Lincoln and there apologised to Lieut. Wilson for having put forward his idea without his permission, and perhaps prematurely, however, they agreed that come what may, they would find a solution to the mechanical difficulties… The reference on Page 31 [of Stern’s book] to a 60 foot wheel is only accurate in that assuming the same co-efficient of adhesion, it would require a 60 foot wheel to mount what the Wilson machine [Mother] would mount, but this is the only connection as the rear end of the Wilson Machine is almost flat and it is this and the position of the centre of gravity that is quite as important as the shape of the front and it can in no way be compared with a wheel of any diameter.’ Now, given this, and given that depending on who one reads the size of the big wheel which supposedly influenced the shape of Mother's track frames is anything from 16 feet to 60 feet, as far as I'm concerned the issue is settled - it is a canard, a myth.

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I think we may need to draw this discussion to end , at least within the forum (if only to avoid boring the pants off some of the other readers although it still interests me). So I’ll post my last comments and then shut my turret hatch on this one.

 

I think that Wilson’s notes are somewhat disingenuous (why, who knows, for he deserved full credit for the overall design). As anyone who has worked in the tyre industry as I have (3 years at Fort Dunlop) can testify adhesion is largely a coefficient of ground contact (which is why many modern tyre designs produce tyres whose curves flatten out as the wheel turns to increase ground contact and thus adhesion and traction. Maximum contact and adhesion etc is achieved with a smooth tyre on a perfectly smooth and dry surface but treads must compromise this to deal with wet etc)* In essence Wilson’s qualifying notes are saying that the front end of the tank had effectively the same ground contact as a big wheel (which is basically what I said at the beginning of the thread) but he is wrapping it up in engineering terminology. This is perfectly consistent with what Stern reports that Tritton and Wilson said to him. Why Wilson should wish to obfuscate this is probably lost within the mists of time as it is perfectly sound engineering. Was there some disagreement with Tritton (possibly over the merits of the Medium B and C designs) that might have caused him to wish to play down any inheritance from the latter’s big wheel work? We’ll never know.

 

Well there we are.  We may have to agree to disagree but I think I’ll go hull down on this one now.

 

* of course too much adhesion can then compromise turning ability which is why so much abstruse calculation and computer modelling now goes into designing tyres and why the Mk V* had steering problems.