Gun Chatter

[zoomzoom 2]

Was wondering if anyone here knew what the standard was for synchronisation of the mahcine guns on WWI fighters, namely the Albatros series. My question isn't regarding the sync between the guns and the prop, but in fact rather, with each other. I know there were two thumb triggers on the cyclic, so that would indicate to me that if you didn't hit them at precisely the same time you might get that, "what I call" dual gun stuttering that you hear very distinctly in films like the Blue Max, where you can tell both guns are firing, but sometimes in sync, and at others " out of sync" with each other. Anyone have any info on this, as I am playing with some more realistic sound byte attempts, and am deciding if this might be something to reproduce.

 

TIA

 

ZZ.

[Flyby PC 23]

I confess I don't know the firing mechanisms of WW1 guns, but I do know you can adjust the rate of fire with modern weapons by adjusting the gas port. A machine gun on sustained fire roll, (perched on a tripod or vehicle) typically has a much faster rate of fire than a weapon carried by an infantryman. Depending on the setting, two outwardly identical guns might not be synchronised to fire in time with each other.

 

The big difference for WW1 aircraft comes with guns synchronised to fire through a propellor. The mechanism regulating the firing would not let guns fire in and out of sync, or else one or other gun would also fall out of sync with the propellor.

 

I haven't read up on it, but its my guess your guns would remain perfectly synchronised, but your rate of fire would vary with engine speed.

 

That's my tuppenceworth anyway.

Edited February 17, 2010 by Flyby PC

[zoomzoom 2]

Thanks Flyby, thats a start. My suspicion is a bit different though....that being that they were ONLY synched to the prop, and not each other. Thats why if you had one gun jam, say the left, you could still fire till your belts were empty with the right. Also, I am not aware of any mechanism installed that would thereby connect and synch the two guns with each other....why would this even be necessary? And the weight would be inefficient in an aircraft. Its my hunch, and I'm hoping for more accurate infor to prove it right or wrong, that if you hit the triggers one after the other (ie not exactly simultaneously) you get a faster sounding rate of fire because one is firing in the "gaps" of the other. Also, because the propellor is passing each at a slightly different time, the interuption would also cause the "ragged" stuttering in extended firing. So, a more accurate gunfire sound would be periods of simultaneous fire, mixed with periods of more rapids sounding "out of phase" or "non synched fire" somewhat alternating.

 

ZZ.

[Flyby PC 23]

Might be my mistake, but being synchronised doesn't mean firing at the same time ie simultaneously. The bullets from either gun have to hit the gap between the propellor blades, so I would guess one gun would fire a little before the other to fit the revolution of the blade, but the rate of fire for both guns would be governed by the propellor speed.

 

Regarding jams, I suspect the most common jam would be more of a stoppage rather than an actual jam. - By stoppage, I mean a round becomming stuck in the breech, requiring a manual re-cocking of the weapon to expell the dud round, load a new round into the breech, and draw back the firing pin ready to fire again. If it's like a modern gun, it's the gases behind the exploding bullet which forces back the firing mechanism to 're-cock' the weapon, and spring forward again to fire the next bullet, so one dud round breaks the chain of events and will cause a stoppage. Re-cock the weapon and you're firing again.

 

A 'jam' proper would I suspect involve some breakdown of the gun mechanism itself, perhaps damage from incomming rounds or shrapnel, and I don't think the pilot would be able to fix that. Thats a job for the armourer back on the ground.

 

With a stoppage, the gun mechanism (and interruptor mechanism) will not be damaged, just need the weapon to be re-cocked. With a jam, or damage to the weapon, I doubt the interruptor gear would drive the firing mechanism, so while the damaged gun might be dysfuntional, I don't think that would jam the moving parts of the interruptor mechanism of the other gun. It would be a bad bit of design if it did.

 

What is worth a read was a thread by RAFlouvert - about the fluid mechanic scientist and the British Captain who recognised the application for the scientists experiments. The British had a hydraulic fire control mechanism. I wouldn't even try to explain it, but I'll try to find the link. It's a good read if you're interested. (You reading this Lou? - help!)

[zoomzoom 2]

"A 'jam' proper would I suspect involve some breakdown of the gun mechanism itself, perhaps damage from incomming rounds or shrapnel, and I don't think the pilot would be able to fix that. Thats a job for the armourer back on the ground.

 

With a stoppage, the gun mechanism (and interruptor mechanism) will not be damaged, just need the weapon to be re-cocked. With a jam, or damage to the weapon, I doubt the interruptor gear would drive the firing mechanism, so while the damaged gun might be dysfuntional, I don't think that would jam the moving parts of the interruptor mechanism of the other gun. It would be a bad bit of design if it did. "

 

 

Correct, in essence, if the mechanism were damaged, there wasn't much one could do. If a round fouled or got jammed from the belt feed though, cycling through the rounds via the cocking levers could clear it and put it back in action....if you are lucky. And sometimes the hammer worked or didnt when rounds jammed in the breach. As far as accuracy is concerned though, I think we are overating the innacuracy....well...in that deflection shooting would be impossible. This just isn't so...nomatter how bouncy the vibrations of the guns firing atop of a humming engine may be. Thats why there were tracers...you can guide that fire-hose stream of lead right onto target...we aren't sniping here at a miles distance after all.

 

But back to what you said Flyby..about them not synching to each other. I have not yet seen that this was done..in other words both barrels popping at the exact same time when fired...and like you mentioned, due to propellor timing, as well as two different triggers, I think (barring other factual unknowns) that a sometimes in sync, sometimes out of sync variance would be heard with these guns.

 

ZZ.

 

 

 

So...in essence you would hear while firing : pop.....pop.....pop.....pop......pa..da..pa..da..pa..da..pa..da..pop....pop...pop

 

The "pop's" of course, being when in synch with each other...and the "pa-da's" sounding faster and when they are out of synch.

 

Sorry....I'm also a drummer, and this is how we talk sometimes.

Edited February 18, 2010 by zoomzoom

[Flyby PC 23]

http://fluid.power.net/fpn/const/

 

It's not Lou's link, but thats the scientist....

[zoomzoom 2]

Very interesting link Flyby. Much more technically svelte than the German geared design.

 

ZZ.

 

 

[Flyby PC 23]

I understand you Zoom Zoom, but think about it from the other direction. The gap for the bullet to pass through rotates at a constant speed, so both guns would need to fire at the same rate to hit the gap as it passed by the muzzle. If one or other gun fired faster or slower, it wouldn't coincide with the gap and hit the blade.

[zoomzoom 2]

I see your point, but if you look at the overall arc of the propellor, the blades actually take up only a very small portion. Granted they are revolving insanely quickly, thus reducing the window of opportunity....but I still am not convinced that due to this fact, an in and out of sync stutter wouldn't occur.

 

ZZ.