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Super Aereo

Spitfire Vb Underwing 250lbs Bomb Carriers?

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No, that's definitely (there I go again...) a 'b' wing. There had been talk about introducing belt feed, but Joe Smith/Supermarine convinced the authorities that the "Universal" wing (which was developed for belt-fed from the beginning) was the way to do that, not have yet another variation in between. Aside from the cannon placement, there's the gear leg angle and (if you can make it out) the position of the .303, since that moved out one rib bay on the 'c' to make room for cannon ammunition.

The question of muzzle brake is interesting. I'll see if I can find any comment in the Spit V manual that gives a hint. It may be as 'simple' as a different strength spring being required, which I would think would be a replaceable item. I do remember some comment while testing installations about strength of spring (or whatever they called it) and its effect on reliability. EDIT: Only comment seen on first pass is that Vc can use either Mk.I or Mk.II Hispano.

Alas, I haven't had a chance to go searching for info on wing bombs on Vbs, nor have I fortuitously stumbled upon information while looking for something else, which is how it usually works!

bob

Edited by gingerbob

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Let's just say I missed my friends.

Good to see you back Edgar.

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No, that's definitely (there I go again...) a 'b' wing. There had been talk about introducing belt feed, but Joe Smith/Supermarine convinced the authorities that the "Universal" wing (which was developed for belt-fed from the beginning) was the way to do that, not have yet another variation in between. Aside from the cannon placement, there's the gear leg angle and (if you can make it out) the position of the .303, since that moved out one rib bay on the 'c' to make room for cannon ammunition.

The question of muzzle brake is interesting. I'll see if I can find any comment in the Spit V manual that gives a hint. It may be as 'simple' as a different strength spring being required, which I would think would be a replaceable item. I do remember some comment while testing installations about strength of spring (or whatever they called it) and its effect on reliability. EDIT: Only comment seen on first pass is that Vc can use either Mk.I or Mk.II Hispano.

Alas, I haven't had a chance to go searching for info on wing bombs on Vbs, nor have I fortuitously stumbled upon information while looking for something else, which is how it usually works!

bob

That Hispano comment might just answer your question as the main difference between the Hispano MkI and MkII was that the Mk I was drum fed and the Mk II was belt fed!

Selwyn

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That's not right. I don't remember the differences offhand, but it is clear that either Mark of Hispano could use the belt. There's a different linkage or bracket to fit (and the alternate had a place to live in the gun bay). No doubt the Mk.I Hispano was originally designed to use the drum.

bob

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IIRC, the Mk.I Hispano was pretty much the original version of the weapon as used on Spitfires Mk.Ib and Westland Whirlwinds (among others), while the Mk.II was the first production version adapted to British manufacturing practices and the first one to use the belt feed mechanism produced by Molins.

From what I read in G. F. Wallace's book, the belt feed mechanism necessitated more than just loosening the spring, hence the removal of the muzzle brake.

Incidentally, it seems quite difficult to find accurate information on the various versions of the Hispano 20mm.

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Many thanks for the fantastic drawings, Edgar! Amongst other things it shows a type of recoil spring I was unaware of!

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This still leaves the conundrum of the Mk.Vb with bomb carriers in the photos above: was it a one-off experiment? Or was it a modification that could have been used operationally..? So far I haven't been able to find anything on the subject.

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My grandfather was at Gzria in Malta and appears to have fitted three bomb kits on spitfires. I have his inspection book. I will post the serial numbers when I get home.

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According to Prosser Hanks, the only Malta Spitfires converted to carry bombs were Vc, using the outer 20mm cannon stubs for cannon, with the so-called bomb racks fitted where the inner guns were normally housed.

The only visible sign, once the bombs were dropped, was a strip of metal about 1" deep. The "sway braces" were nothing more than steel rods fitted into holes drilled partway into the bombs, then into the wings themselves. The rods left when the bombs left.

Park complained about the policy of cutting off the outer cannon stubs, to make the leading edge smoother, because it was stopping him turning the Vc into bombers.

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Do you have a list of "mods" for the Spit, as my grandad lists a few as local, the others with a number. Such as Mod xxx.

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I've copied the entire Vickers Spitfire/Seafire modifications ledger, which the RAF Museum's library holds. If it's a genuine modification, I should be able to find its reference.

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What do you mean by genuine. What a great way to put someone of sharing.

I shouldn't read too much into it. I assume by 'genuine' Edgar meant 'Supermarine approved'. Presumably any ad-hoc local mods would not have made it onto the list Edgar has seen.

I for one would be interested to hear of the local mods your grandfather noted.

Regards,

J.

Edited by JasonC

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What do you mean by genuine. What a great way to put someone of sharing.

And so is a response like that. Jason has it right.

bob

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Ok, let's start again.

He was stationed initially at kalafrana, then Gzira. The book is quite confusing, I find his writing hard, and lots of technical terms. I also don't know what unit he was in.

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What do you mean by genuine.

Genuine = Air Ministry approved; Malta's bomb conversion wasn't, so it wasn't, and looking for a number will be a waste of time. Other bomb-carrying mods were approved, and (as so often happens in the research world) it would be tempting to tie them all together.

Every mod had to go before the Local Technical Committee for approval, or otherwise, and this is something, in today's more relaxed atmosphere, that modellers often have great difficulty in understanding.

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How do you post photos?

There are walk through guides in the FAQ section here and depending on the photo hosting site you use, the 'how to' will vary.

Trevor

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Genuine = Air Ministry approved; Malta's bomb conversion wasn't, so it wasn't, and looking for a number will be a waste of time. Other bomb-carrying mods were approved, and (as so often happens in the research world) it would be tempting to tie them all together.

Every mod had to go before the Local Technical Committee for approval, or otherwise, and this is something, in today's more relaxed atmosphere, that modellers often have great difficulty in understanding.

When one reads about the work of W/Cdr Louks on Malta, the very last impression one gets is of stubborn, hide-bound, hierarchical unresponsiveness, but rather of vision, innovation, improvisation, tremendous flexibility and very rapid implementation, all backed by huge engineering expertise.

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So it reads

"Local Mod for Spit .V.

All a/c not fitted with new type cockpit hood incorporating spring retaining device for hood jettison bars.

Title Fitting of retaining device to hood jettison bars to prevent loss of hood due to jettison bars v/u????ty out of poss."

He then outlines 9 steps to make devices out of steel and elastic.

Stuart

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Trying to decipher is this a description of part of the Malta Bomb Mod? or something else.

See https://plus.google.com/+StuartBeanCaptAhab/posts/TNmLJi4TKrRfor image

Sequence of operation of Mod

Remove aileron SBD

remove inner and outer flap SBD

first lower flap and joggle retaining slug of return jack.

Remove 1/4 bolt and SBD riser and ???? rod aileron. Remove B????? Remover aileron flap.

Drill hole 5/8 3" Rear of second electrical fitting F/U. Remover seat

Pass cable through F/U through rear of electrical cable.

Drill holes 1/2" 9" from F/U rear and clear gun heater pipes at root end M/P.

Pass cable through lightning holes and drill holes through solid riffiles?

Pass cable through rear eigty? hole under jack flap and affix bracket over top of control aileron cables and through small lightning holes end of flap. Recover out to size?

Use rubber on all holes made.

Use of clips to tails? of slack cable round to no 12 rib.

Between guns Remove two panels for ease.

Cover plate and attachment plate supplied.

Cut out to size holes, affix bracket use two paddy pliers?. Use wooden block for position of bolt holes for mast holes made in Plate? case? for position of block?

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