field modified SAAF blenheims

[beppe]

Does someone have pictures/drawings  of field modified SAAF blenheims mk IV with 20 mm hispano gun ?

 

 

Cheers,

 

Joseph

 

[brewerjerry]

Hi

    Some info here 

http://forum.12oclockhigh.net/showthread.php?t=38475

   cheers

      jerry

[tonyot]

Here is one;

Don`t forget to add the gun pack below the belly too, with cartridge chutes added and the reinforcement blast plate above the muzzles.

 

Cheers

             Tony 

[beppe]

Thanks Jerry and Tony,

 

I guess the gun was drum fed.

 

[Graham Boak]

That's a curious combination, pointing to the local (theatre rather than unit, I suspect) nature of the change.  The gun pack on the Mk.IV didn't need those blast protectors, because it was deeper.  This one is a gunpack from (or for) a Mk.I.

[tonyot]

The cannon in the nose was indeed a drum fed 20mm gun taken from a Hurricane. ` Sqn SAAF had removed 2 cannons from their Hurricane Mk.IIc`s so there some spares going around!  I think that they had light stores carriers fitted under the rea fuselage too.

 

You are right about the gun pack Graham,....... I did bring this up in a discussion some time ago that some Mk.IV`s had the smaller style gun pack fitted,.......but I was shot down in flames, so I retired gracefully from the scene and left the experts to it.

 

Cheers

              Tony

 

 

[beppe]

Thanks Tony, 

 

I wonder if latched or welded to the floor.

 

About the gun pack, i thought the size depended on the amount of ammunition carried.

 

 

[tonyot]

3 minutes ago, beppe said:

Thanks Tony, 

 

I wonder if latched or welded to the floor.

 

About the gun pack, i thought the size depended on the amount of ammunition carried.

 

 

I would say that it was fitted to the floor in a removable mounting,.......they wouldn`t weld a gun to the floor, there would be quite a lot of recoil. 

Wasn`t the ammo for the belly guns carried inside the bomb bay? 

 

Cheers

            Tony

[beppe]

sounds right indeed

 

[Graham Boak]

I don't know about any other examples, but that one surely does.  The gun pack was a modification (the parts being built in Southern Railway workshops) that required the removal of the bomb-bay doors, the structure supporting the gunpack was attached to the roof of the bomb bay.  Presumably (sensibly, anyway) it attached to the same strong points as the bomb carriers.  Aircraft could be converted from bomber to fighter and vice versa in a short time on the unit - although quite how the blast protectors were attached I don't know.  Maybe once fitted they were retained?

 

The pack fitted to the Mk.I was as small as could be achieved, in the interest of low drag, but this did result in damage to the forward fuselage skins so the blast protectors were fitted.  The deeper gunpack of the Mk.IV was reputedly to clear the reshaped nose of the Mk.IV but placed the guns low enough for there to be no blast damage.  As here we have a Mk.IV with the smaller pack, it seems that the tale of "deeper to avoid reshaped nose" doesn't prove necessary.

 

Is it only fighters that were fitted with the 20mm cannon?

[tonyot]

Maybe the guns in the smaller gunpacks were fitted slightly depressed downwards to help clear the slight droop in the nose of the Mk.IV? As the cannon armed aircraft were primarily `strafers' then it makes sense to have a gunpack fitted too and I`ve only ever seen the cannon fitted to `fighters',..... plus the cannon would take up the room of the bomb sight too I presume? 

 

If the guns were slightly depressed downwards it would not matter as long as the gunsight was hamonised or `zeroed in' with them. 

 

Cheers

            Tony

[Charlie Hugo]

Here is another picture

http://fjexpeditions.com/desert/history/GJMostert/slideshow.htm?105

[Graham Boak]

In principle yes, though given the tightness of the package it isn't clear just how much adjustment could be available.  Not just for rotating the guns to a different fixed position but finding and fitting new feed routes.  Little adjustment beyond that needed for calibration would be designed in because downward sloping guns would not be desirable in air-to-air work,which is the design purpose.  It might work, for strafing, just to turn everything to maximum tolerance downwards, but you might get undesirable spread even in that role.  

 

Having downward firing guns for strafing is an idea that comes up time and again, particularly in Russian thinking, but it rarely seems to be widely adopted.  Presumably because of the difficulty in aiming at other than small angles (which would apply here anyway).

[tonyot]

I didn`t mean drastically pointing them downwards Graham,.....just enough to clear the very slight dip of the nose,...which would no doubt be able to be done via the calibration movement of the mounting. And their main role was for ground strafing, not air to air anyway.

Cheers

           Tony

[Graham Boak]

The air-to-air comment was directed at the original design requirements not this fit.  

 

Just how drastic is drastic?  I wasn't thinking of 45 degs or thereabouts either, just any more than was built in already.  I'm unsure that the very minor adjustments available for calibration would have been sufficient, but then I've not seen the values for that nor schematics for any additional projection of the new nose into the spread of fire of the original mounting.  I think this is the kind of discussion that requires more precise information on such details.  I have an opinion, which is that getting the guns lower to avoid blast effect was much more important, but that is only an opinion because it is not the reason usually given.

[beppe]

4 hours ago, Charlie Hugo said:

Here is another picture

http://fjexpeditions.com/desert/history/GJMostert/slideshow.htm?105

Nice picture, thanks a bunch

Joseph

[Garry c]

If the were using "spare" cannons, might they also be using spare Mk I gun packs? Not ideal but readily available.

 

Garry c

[Drift]

Some very useful info here. Thanks guys. 

[Graham Boak]

4 hours ago, Garry c said:

If the were using "spare" cannons, might they also be using spare Mk I gun packs? Not ideal but readily available.

 

Yes, where else would they get them from?  Presumably there were no Mk.IV gunpacks in theatre.  The question remains why, if this was possible, there was a different gunpack for the Mk.IV in the first place?  A common statement is the need to clear the new nose, but were this true then fitting Mk.I packs would be a very bad idea.  I've seen comment that, even with the blast protectors, the Mk.I fighters suffered structural damage - loose rivets etc).  Either this wasn't known in theatre, or a decision was made to accept such damage for the operational value.  The more cynical might suggest that with high loss rates any incremental damage would not accumulate to important levels before the aircraft was lost anyway.

[Seahawk]

We last discussed 20mm-armed Blenheims here:

 

No help on gunpacks but may be useful regarding other aspects.

[brewerjerry]

Hi

    Not sure if anyone has seen this

  could it be the only 1940's gun pack left ?  

   maybe a Bm'r may visit it with a tape measure one day 

http://pierrekosmidis.blogspot.ca/2015/11/found-salvaged-and-restored-blenheim.html?m=1

   cheers

      jerry

[Selwyn]

12 hours ago, Graham Boak said:

 

Yes, where else would they get them from?  Presumably there were no Mk.IV gunpacks in theatre.  The question remains why, if this was possible, there was a different gunpack for the Mk.IV in the first place?  A common statement is the need to clear the new nose, but were this true then fitting Mk.I packs would be a very bad idea.  I've seen comment that, even with the blast protectors, the Mk.I fighters suffered structural damage - loose rivets etc).  Either this wasn't known in theatre, or a decision was made to accept such damage for the operational value.  The more cynical might suggest that with high loss rates any incremental damage would not accumulate to important levels before the aircraft was lost anyway.

Remember this was wartime and everything was in short supply. You don't stop using equipment on ops  just because it did a bit of skin damage when fired.

The shallow mk 1 gunpack had its faults causing blast damage, but it wasn't dangerous to the blenheim when fired, and they designed the supplementary  panel to minimise blast effects which was probably a short term quick fix solution whilst they sorted out the problem. The Mk 2 gunpack was designed and put in production, being  deeper and more rounded at the front with the guns set lower to minimise blast  damage, but it appears that some  Mk IV aircraft with themk 1 gunpack blast panel fitted with the retained it in place as well. I possibly  both types of pack were used on some IVF units and were interchanged as required?

 

Selwyn

 

I have also seen drawings of a gunpack somewhere with a double angled front panel. Was there a third type of gunpack out there, or was it somebody's artistic licence?

 

Selwyn

[dogsbody]

No. 404 Squadron had Blenheim IV's with gunpacks and blast protectors.

 

 

 

 

 

Chris

[DaveCromie]

Chris

 

Those are great pictures, thanks for sharing! I particularly like the last one as is also shows the hedgehog exhausts that when combined with the gun pack and blast protector would make a very intersting model.

 

Thanks again

 

DC

[Graham Boak]

12 hours ago, Selwyn said:

Remember this was wartime and everything was in short supply. You don't stop using equipment on ops  just because it did a bit of skin damage when fired.

 

I have also seen drawings of a gunpack somewhere with a double angled front panel. Was there a third type of gunpack out there, or was it somebody's artistic licence?

 

The damage was considered important enough to create a new design that avoided the problem.  On the other hand, not important enough to insist upon a modification programme for the existing packs.  Given that the Mk.IF was still in use in December 1941, that's quite late enough for such a modification programme to have been effective, had it existed.  I don't know about this third variant, and suspect someone's misunderstanding, but it could have been just such a modification to the earlier packs.