CANNON..The Second World War Aircraft Gun

Nice to put a face on Martin Bull. Honestly thought he was a WW2 vet living in a home. ..Glad to see he should be with us for a long time. Cheers Mr Bull.
Did the Molins have a feed problem when flying anything but straight and level?...There was some good info regarding that somewhere here. ..Feel a little dirty looking at a naked 57mm.

 

Hey - I feel pretty cool.......

Er....suddenly I don't.......

 

Pardon me. Never meant any disrespect. Love the Bull.

 

The Germans came up with an flak gun in the basic caliber range that you people are talking about. It was set up to have negligible recoil. The piece was the 5.5cm Grerat 58. To keep the gun from tearing its mount it was designed with a differential recoil system. The idea behind it was that the gun was cranked back to the limit of its recoil and then held there. When the gun was fired the barrel shot forward. Just before the barrel reached its forward limit the gun went off. The recoil shoved the barrel back to the rearward limit where it was held there again. The force of the barrel going forward counteracted the recoil of the gun being fired. The USA used this system in the Vietnam war in our "Spooky" cargo planes converted to gun ships. It enabled us to fire a 105 howitzer out the side of the airplane without really even moving the ship about. This type of system would have been great in a Mossie or B-25! I guess the concept has been around since WW1. I wonder why no one thought of it?

 

The concept was thought about and incorporated in some mountain guns even before WW1. I understand a similar recoil system is used in the 75mm M6 in the B25 and M24 Chaffe. The British were not enamoured of this system for other reasons. What happens in the event of a hang fire? GOK where the round might land! The Molins 6 pdr worked well enough in the Mosquito without a differential recoil. I suspect the reason why aircraft mounted artillery fell out of favour in WW2 in comparison to FFR was because a cannon needed to be used within the range of low level AAA, whereas rockets could be launched from further away. Yes the C130 gunship uses a 105mm, but would not be used against the kind of AAA possessed by the Wehrmacht flak arm.

 

The problem with unguided rockets is that they are unguided. The reason I believe they were used was lack of recoil, but cannon are much more accurate. I don't think that rockets, used beyond light AAA would be all that effective. All I've got to go on is gun camera footage, but those seem to show attacks on German shipping well within 20mm range. Actually, cannon can be fired accurately from quite high up. Trajectory is computed on horizontal distance, not vertical. So, the steeper the dive, the less you have to worry about the projectiles dropping. Also I believe a hang-fire would be an equal problem no matter what cannon system was used.

As an aside, the Ju 87 with the 37mm cannon was quite effective against Soviet armor despite the Soviets having a lot of light AA.

 

Hey - I was only kidding ! No disrespect meant and none taken - in fact, I had quite a laugh.......

 

The channel 4 doc "the Plane that Saved Britain" (still available to watch online @ 4OD) has footage from the mosquito museum with the cannon Mr Bull is standing beside in case anyone is interested. The Boys Own style is a bit annoying (they use one of the novels to illustrate an attack at one point) but they have an interview with a pilot who used this in anger. He says at one point that the recoil zeroed all his instruments for a moment.

 

What this says to me is that if you fired this weapon in a mosquito and weren't going at full speed, then you risked stalling out at low level! I wonder how many rounds the mossie could take before structural failure?

 

IIRC (and i may well not) *i think* he said there weren't ANY....did i get enough qualifiers in there?
Ill see if i can double check and get a few more details. I was only really watching it out of the corner of my eye but i was struck by the size of the thing, and then seeing this thread i thought id poke it in passing.

Edit 6.06pm GMT:
Just rewatched that section again as i was doubting what i remembered.

From: "The Plane That Saved Britain"

EdIt 2 (sorry) Just reread Martin Bull's post so to bring it full circle ill quote him:

 

To be fair, the Molins guns' designed use was strictly offensive, not defensive. Therefore any firing would be expected to be at high speed. The hesitation due to recoil was noiceable but momentary. As for structural damage, the normal Mossie FBVI carried 4 x .303 and 4 x 20mm in the nose which when let loose imparted a lot of recoil forces into the airframe........

 

Amazing!!

 

Great reading. Voted.