Crusader with 25 Pdr

[William Marshall]

Came across a Tech report (1944) stating that a Crusader had been mounted with a 25 Pdr and handed to the School of Art for trails. Does anyone have more details of this, drawings, pictures, info, etc would be much appreciated.

 

Regards

 

William

 

 

Edited January 7, 2019 by William Marshall
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[Kingsman]

One might suppose that it used the Gun Tractor superstructure as a starting point. As discussed on this site in the past, Argentina converted some Crusader gun tractors post-war into 105mm SPG like this.  It could perhaps be speculated that they got the idea from the alleged 25pdr experiment/prototype, if it existed.  Maybe they got it and cloned it?  There are pics and drawings around of a 5.5" SPH on the Crusader, but nothing on a 25-pdr as you say.  There was a 25-pdr Archer prototype too.  Everyone seemed to be looking at ways of making 25pdr SPs: Australia converted a small number of M3 Lee or Grant post-war into substitute Sexton, called the Yeramba.

[Kingsman]

Ah.  The document just displayed as a link when I first looked.

 

Obviously not a Gun Tractor conversion, then.  It all sounds very Heath Robinson and the report itself is very scathing about the practicality and reliability of the conversion.  I'm not sure it even qualiifies as a prototype, but having said that the first workshop lash-up 17pdr on a Sherman at Lulworth became the Firefly once Chertsey and Vickers became involved.

 

Even from that brief description I think we can deduce what it did look like, at least in principle.   Enough to have a go at making it: without pictures or drawings it can't be held to be wrong as long as it makes mechanical sense.

• Your Crusader kit would need the turret ring opened out to the correct diameter as a starting point. 
• And you obviously need a MkII 25 pdr.  I believe that Dragon's is OOP.  Bronco?
• If the shield is square then the framework must have supported a square floor. But we don't know if it was open over the turret ring.  I suspect not as that might have impeded serving the gun and there would be no room for anyone to work below e.g. passing ammunition.  And ejected charge cases would fall through.
• We also don't know what its height was relative to the gun trail, but as the 25 pdr was normally served from standing on the ground it must be below the trail,
• This means that the precise detail of the framework will be hidden under the solid "turret" floor and need not be a huge concern for correctness as it will not be seen.   However, there will need to be brackets of some sort to secure the trail to the framework, and we have no idea what these were like nor anything to copy from.
• I wonder if a Crusader AA Mk1 with the Bofors mounting might be a better starting point than a gun tank?  The turret base might be a useful staring point, and you get a spare Bofors gun, sans mounting.  Indeed, might the "designers" have looked to the AA Mk1 turret for inspiration?  It was around in 1944.
• We know the height of the shield, but not the side length. 
• We know it was square in plan view, and can reasonably assume it didn't overhang the tank's sides as a max width - and therefore length.
• We might assume that the corners did not extend beyond the tank width at 45 degrees traverse, but that's a stretch and I suspect would make the working compartment too small for the immediate gun crew of 3-4.
• As a size guide, the Bishop's rectangular turret was only long enough for 4 men to work with the rear doors open for the loaders, who sat on the door lip.
• There would be a sighting slot to the left of the gun.
• With no on-vehicle ammunition stowage we might assume a drop-down flap in the rear plate to facilitate passing ammunition from the engine deck for trials - but there is no evidence, it's just logical.  Bishop stowed ammunition on the turret walls, but it is unlikely that this would be done for this "prototype".
• We know that "removed wheels" are mentioned but not the axles.  These bolted on underneath the trail, which made them easily removed to leave a flat underside.  So they may have been removed.  But the Bishop installation compromised elevation so it would have been necessary to keep the trail in roughly the same attitude as on its wheels, sloping down to the rear at about 15 degrees with the spade dug in.  Tipping it level will take out that much elevation: not good.  Keeping the axles and perhaps fitting them into some sort of bracket or stirrup would help keep the right attitude.  That's what was done with the SIG33 on the Sturmpanzer 1 Bison.
• We know that the trail was cut down, but exactly where is a function of the turret length.  It is also a function of keeping the trail reasonably at the same angle as when on its wheels.  I think it is fair to assume that it would have been kept as long as possible to distribute the recoil forces mentioned in the document.
• No sand shelds to save weight.
• Probably slightly nose-down supension attitude compared to normal.
• Hull colour most likely Khaki Green 3 or KG3 and Green 5.  Possibly SCC2 but production ceased at about the time of the change so this is very unlikely.  Conceivably the conversion was repainted in SCC15.

[Kingsman]

I know we're not talking about the Archer conversion here, but I found a couple of photos of it so here they are FYI.  25pdr Mk1 gun: no muzzle brake.  Still not a simple conversion as the 17pdr on Archer was the tank version with inboard recoil system rather than the field version with under-barrel recuperator.  But the structure would certainly be capable of absorbing the lesser recoil forces.  An easier kit conversion prospect.  Didn't find any interior pics.

 

 

I don't think this one is genuine colour.  I think it just has a sepia tint.  Same vehicle, same place - so probably taken at the same time.

[William Marshall]

If I look at the suspension this seems to be a A10 Cruiser tank mod! Very interesting all the same! Thanks very much for the pictures!

Edited January 8, 2019 by William Marshall

[Andrew Jones]

3 hours ago, William Marshall said:

If I look at the suspension this seems to be a A10 Cruiser tank mod! Very interesting all the same! Thanks very much for the pictures!

Based on the Archer , so a Valentine chassis not A10

[Kingsman]

Valentine of course inherited the same basic suspension from A10 and A9, with some wheel differences across the Marks and different tracks.  The 25pdr SP is definitely a Valentine-based Archer.

[William Marshall]

The pics you supplied does not seem to match the description, as the 25 Pdr mounted would have a 360 deg ability to traverse, the pictures show a fixed type of turret.

[Kingsman]

2 different vehicles.  There are no known pictures of the original Crusader conversion.

 

The Archer conversion photos are just for interest while we're talking about 25pdr conversions that went nowhere.

[William Marshall]

Interesting all the same!

 

[Seahawk]

The SP 25 pdr designs on both the Crusader and Archer hulls sound like exercises in futility in that they don't seem to offer any advantages over the perfectly adequate Sexton.  The Crusader design sounds like a lash-up which MIGHT have looked a bit like a regunned Bofors Crusader AA tank.  But it was probably a less completely fatuous design than the SP 5.5" gun on Crusader chassis  (for which one can at least see a business case) where the driver sat in the rear corner of the fighting compartment behind a completely unshielded 5.5" gun: impractical for driving, impractical for operating the gun in action.  What was the point?  (Photographs are available of that one.)

[Kingsman]

Er, hang on a mo here guys..........  Re-reading the tech report it says Cruiser Mk IV.  We've all missed the fact that the Cruiser Mk IV was in fact the A13 MkII !!.  The Crusader (A15) was the Cruiser Mk VI.

 

No wonder the report is worried about overload on that 4-roadwheel chassis.  It was that element that made me look back, thinking that Crusader's weight can't have been so borderline that +1 ton would represent a problem overload.   By 1944 the A13 was well obsolete. 

 

While I can understand the possible thinking behind a Crusader SPG in 1944 - bearing in mind its then-current use as an AA SP - using an A13 chassis surely falls into the category of "faintly ridiculous desperation".  It would have been a better prospect on some of the 500 or so otherwise-useless A24 Cavaliers (Cruiser Mk VII), of which a few were used as RA OP tanks in NWE.  Cavalier at least had the benefit of the 410 BHP version of the still-unreliable Liberty engine.  While there were 4,000-odd A27L Centaurs (Cruiser MkVIII) kicking around that tank reverted to the little-less-unreliable 340 BHP engine version and needed a weight-reduced hull with weaker suspension as a result: so weight and recoil force might still have been a problem.

 

The Archer conversion actually makes a lot more sense than anything on a Cruiser chassis as the relatively high speed of the Cruiser wasn't really necessary for an SPG and, as can be seen, was a relatively much more straightforward prospect.  Assuming that it might have been intended more as an assault gun, an Infantry Tank chassis made more sense - although the jury is still out on whether the Valentine really was an infantry tank.  And in that role the Cromwell Mk VI CS and Churchill Mk VIII CS seemed adequate.  The 95mm howitzer was larger calibre, although it still fired a 25lb HE shell, and there was HEAT ammunition for it.

 

I can't find any photos online of an A13 25pdr conversion and I don't ever remember seeing any anywhere in the past.

Edited January 13, 2019 by Das Abteilung
correction