Gun turret safety

[Synthetic]

I was wondering whether there was any mechanism that stopped turret mounted guns hitting their own aeroplane? The Stirling came to mind particularly where the fin/rudder presents a large target to the mid upper turret.

[stepwilk]

The short answer is yes. I'm no expert by any means, but I think the simplest form of safety is cams and ramps on the gun-tracking mechanism that simply won't permit it to be pointed at any part of its airframe. And of course it's a simple matter to put more sophisticated electrical interrupters in place. In any case, I don't think it was possible for a WWII turret to shoot itself down...

[avionic type]

The answer is on Brtish bombers of WW2 they had a collar fitted round the mid upper turret called a gun deflector blister which deflected the gunbarrels over the tail plane and the Navigators dome at the front, postwar aircraft that had electric turrets had an electrical cut out fitted , there was a insulated outline of the tail ect on a drum that did the same thing except it didn't deflect the guns just stopped the guns firing.:ok::ok:

[Genghis the Engineer]

An interruptor cam is certainly still used on shipboard guns such as goalkeeper. I always assumed that the technology went back to WW2 - being pretty obvious and robust.

On ships there have been a few "incidents" over the years where something (say a new radome) was added to the ship but nobody changed the shape of the interruptor cams. I am aware of this happening on an RN Frigate in the early 90s during some modified goalkeeper trials where nobody allowed in the cam design for the shape of a large camera cluster bolted onto the side of the bridge to film the trial. The bridge was, technically, left unharmed -if a lot of high speed bits of disintegrating camera cluster is a technicality that you can overlook.

G

[Lightning Mate]

Typical navy.........

[Peter-RB]

Whilst watching the History Channel last nght I saw a B17 top turret swinging from Port to Starboard and upon reaching the center line the two cannons automatically seemed to raise and then lower as the Fire line swept thru the sect that would contain the tail fin, .

Peter R-B
Lancashire

[sisemen]

Lancaster mid-upper turret:

http://www.lancaster-archive.com/lanc-turret-mu.jpg

http://www.lancaster-archive.com/lanc-turret-mu1.jpg

The operating levers (aka Tabo arms) tracked along the top of the Cam Ring. As the arm rose a gun interrupter mechanism engaged and prevented the guns from firing. Which in turn stopped the gunner from shooting off the tail, Rudder or into the fuselage.

[Noyade]

The workings of the interrupter gear for the Beaufort...

http://img705.imageshack.us/img705/4376/img457d.jpg (http://img705.imageshack.us/i/img457d.jpg/)
http://img638.imageshack.us/img638/8646/img458o.jpg (http://img638.imageshack.us/i/img458o.jpg/)

[India Four Two]

Lancaster mid-upper turret:


sisemen,

That's fascinating. I had always assumed the fairing had an aerodynamic purpose. It never occurred to me that it was an interrupter cam!

[hunterboy]

Probably a stupid question, but is that a reason, that enemy fighters would try to attack from directly behind the tail?

[jimgriff]

....and face four guns from the rear turret? :D

[ZH875]

....and face four guns from the rear turret? :D

four pea shooters against twin 20mm Cannon - No Contest....

[45-Shooter]

Attack from the rear is so deadly to the fighter, which presents ZERO deflection and aim off, which is not the same thing, as to allow one B-17 tail gunner to shoot down an entire squadron of Me-109s! Their instructor and the 11 recruits who followed him!
Also, the front of the fighter with a liquid cooled engine is it's most vulnerable quadrant! One little tiny .30 cal bullet in the Radiator, Oil Cooler, Engine cooling jacket, gear case below the oil level line, oil pan below the level line, etc... Needless to say, a single .50 caliber would certainly hit more than one of those things! While some of those hits were not instantly disabling, they all forced a landing one way or the other. The Spit had two radiators under the wings with a cut out that prevented either one, but not both from downing the plane. The P-51 protected the radiator and cooler with the shape of the duct leading to them, but the engine was still a single bullet kill. The P-38 and 40 were even worse! They had extra coolers to hit! Only radial engined fighters could attack from the front WO too much concern.
The Nazis kept score of those sorts of things and determined that B-17s shot down more fighters than any other type of Allied plane! ( 12-13K IIRC!) B-24s were in second place, (7-8K, again IIRC!) with a huge gap until the distant third place fighter! Can you guess which one?

[stepwilk]

Spoken like a true gamer.

[QuePee]

No matter how good the systems were there was always the chance of a failure. I have no idea what type of preventative system was fitted to the Warwick but attached are a few photos of what happens when an armourer accidently fires one round through the tail of the Warwick from the mid upper turret. Even though it was only one round, of course it had to be an incendiary. The results speak for themselves.

http://i40.tinypic.com/elkax.jpg

http://i40.tinypic.com/33n95xg.jpg

http://i39.tinypic.com/29co2tl.jpg

For the record the aircraft was Warwick BV455 of 293 Squadron and the photos were taken by my late father at RAF Pomigliano.


QP

[RedhillPhil]

I 'spect it was one of ZH 875's peashooters.............

[Grob Queen]

Ghengis and chums,

This is something which I can speak from a knowledge base on as i'm a 20th C Military historian by profession!

You're absolutely correct, we did of course have interrupter gear on aircraft during WW2. But perhaps you may not know that it went back to WW1 - namely 1915. During WW1, the development of fighting aircraft was huge. Triple Alliance and triple Entente each developing their technologies to be one up on the enemy.

Germany were the first to use interrupter gear. In May 1915, the Germans produced a new and fast Fokker which was equipped with the new interrupter gear which enabled the gun to fire through the orbit of the revolving prop without the risk of hitting the blades. The Germans were therefore able to inflict heavy casualties on Allied aircraft and regained air superiority.

If in doubt, ask a specialist historian ;) ...you may all be able to out gun me on the Private Flying forum... :E but I can come into my own on this one :p

GQ

[Synthetic]

Thank you for all your replies.

I thought there had to be something or else it would be just to easy while tracking a fighter with the guns to get an "own goal".

[Genghis the Engineer]

Ghengis and chums,

This is something which I can speak from a knowledge base on as i'm a 20th C Military historian by profession!

You're absolutely correct, we did of course have interrupter gear on aircraft during WW2. But perhaps you may not know that it went back to WW1 - namely 1915. During WW1, the development of fighting aircraft was huge. Triple Alliance and triple Entente each developing their technologies to be one up on the enemy.

Germany were the first to use interrupter gear. In May 1915, the Germans produced a new and fast Fokker which was equipped with the new interrupter gear which enabled the gun to fire through the orbit of the revolving prop without the risk of hitting the blades. The Germans were therefore able to inflict heavy casualties on Allied aircraft and regained air superiority.

If in doubt, ask a specialist historian ;) ...you may all be able to out gun me on the Private Flying forum... :E but I can come into my own on this one :p

GQ

Sorry Grob Queen, but to a large extent you've given the right answer to the wrong question.

Fokker indeed invented the interruptor gear, I think around 1912 - and both the British and Germans knew how to do it by 1914, but it wasn't a viable piece of technology until about 1915 when the consistency of firing times of ammunition became good enough that the interruptor gear had a chance of working. The German amunition manufacturing technology was better, earlier. Prior to that, either the gun was placed well away from the propeller, or the propeller was fitted with deflector plates or wedges. I can only imagine what it felt like to fire through a propeller and feel the response through the airframe as bullets hit the propeller deflector wedges and the ability to actually use interruptor gear must have been revolutionary.

However, we're not talking about WW1-style interruptor gear, we're talking about either an interruptor cam (which prevents firing when a gun tracks across a piece of ship structure) and is used, for example, on goalkeeper, which is a system use to "stop" incoming missiles on Royal Navy ships, or we're talking about a deflector cam, which was used around bomber gun turrets to simply stop the gun pointing at bits of the aeroplane.

Three quite different solutions. Interruptor gear is only relevant to not hitting a regular moving target (a propeller), not a target that is stationary relative to the gun (a ship or an aeroplane). [Let's gloss over for a moment that the term "interruptor gear", which I'd argue only really applies to WW1 technology, got re-used for different technology during WW2.]


Take care historian. In your BA you will have covered a a moderate amount of information and a moderate amount of analysis about some discrete periods of history, whilst on your PhD you'll have done a lot more information an a very high degree of analysis about a very narrow topic. You should not underestimate the massive breadth and depth of knowledge held by a great many amateur historians. Your skill as a historian should be in adding the analysis, and being good at weighing likely conflicting sources of information. As you'll recall, a PhD is really just a research licence that teaches you those very important skills, and a BA was really no more than a primer.

Take care of amateur historians, they may well trump you regularly on their detailed knowledge. Also in a forum like this, you'll find a lot of people who have actually used this kit, providing direct personal knowledge that as a historian you can tap into, but are unlikely to have through your book-learning. You can hopefully play a role in turning some of these recollections into published history.

G