Interrupter or Syncroniser?

Dolphin with Lewis guns on lower wing

This picture is from page 104 of “The British Fighter since 1912” by Francis K Mason and shows an 87 Sqn Dolphin D3775 with a Lewis gun mounted on the lower wing. (RAF Museum Negative no. P011343)

“”In No 87 Squadron the guns were transferred to fixed mountings on the lower wings, somewhat inboard of the inner pairs of interplane struts, where they fired outside the airscrew arc.

Hope this helps.
Andy”

That sounds about right Andy,cheers. Unfortunately I can’t check it up as I can’t get my hands on that issue of Aeroplane-I’ve moved quite recently and I’ve only got a small number of back issues with me at my new place,all the rest being in ‘deep store’ back in London.

Belt- or drum-fed? I almost dread to hear the answer…

Steve
if you’re refering to my post above. They were Lewis guns and therefore drum-fed. The RFC came up with a ninety seven round Lewis drum as opposed to the 47 round drum as used by the infantry.
As the Lewis gun had such a propensity for jamming I can’t imagine the whole 97 rounds were ever fired off without a hitch.
I think the 97 round drum was an invention by another NCO armourer, anyone got his name??
Cheers
Andy

Belt- or drum-fed? I almost dread to hear the answer…

Dolphin.

Ant
The Sopwith Dolphin.

This is taken from ‘Armament Of British Aircraft 1909-1939’ by H.F. King. (Putnams 1971)

“In No 87 Squadron the guns were transferred to fixed mountings on the lower wings, somewhat inboard of the inner pairs of interplane struts, where they fired outside the airscrew arc.

Hope this helps.
Andy

Funny you should mention guns strapped to struts/wings etc on WW1 biplanes. I’ve just been playing “Wings of War” on the PC (WW1-based flight-sim of sorts) and when you receive a gun upgrade, they are usually stuck to the interplane struts.

I wondered whether this was just the programmers way of solving the problem, but now I’m not so sure…! 🙂

I’m sure I also saw an SE5a with TWO Vickers guns in the fuselage, side-by-side, but cannot recall where, or why 🙁

Thanks for the info guys,especially Whalebone. I have to admit I’m surprised that a hydraulic system was used,I’d always thought they were either mechanical or electrical devices. Thanks for your personal anecdotes Whalebone,as Steve Y says it brings the history back to life.

“John C-Did anyone actually fit guns to the wings? If not why not? Were the wings not strong enough or was the drag penalty too great (as the wings weren’t thick enough to take a Lewis or Vickers internally)?”

IIRC,an Australian squadron on the Western Front lashed Vickers or Lewis guns to the outer wing struts on thier Sopwith Dolphins,and apparently had quite a bit of success with them. I don’t know how they were triggered,or what the stoppage rate was like though. It was mentioned in Aeroplane’s Database on the Dolphin a couple of years ago,I’ll try and dig the issue out and look it up.

Thanks again folks. 🙂

Technology…

Whalebone
I think if some sort of measurement of technological progress could be arrived at, you would also find that technology advanced as quickly between 1914-1918 as it did between 1939-45.

As Melv always points out The Great war lasted only 51 Months and in that time aircraft went from looking like The Bristol Boxkite to the HP V/1500 and Martinsyde Buzzard.
Quite some progress.
Andy

Like the Spitfire IX – mix a Merlin 61 (originally intended for bombers) into a Spitfire V airframe, bring to the boil, et voila! A headache for the Focke-Wulf 190! 😀

Quite right James, I think that things technologically always move at great pace as a matter of necessity during wartime. Lots of cleaver heads come up with all sorts of ideas and the best are adopted in rapid order and this continues to be the case.
If you go back just to the Falklands look how quickly the inflight refuelling C130’s came into being, the Vulcan got anti radar missiles and sidewinders were bolted onto Nimrods (all in a matter of weeks) and in the first Gulf war Jaguars suddenly sprouted overwing pylons to give some air to air capabilty.

We have a crisis, we need something to perform a task it was not designed for and we need it yesterday…… history tells us to leave it to the folks at the sharp end to come up with the answer and they generally do.

In peacetime new technology and solutions to problems such as these would have taken years to be implemented.

Victor Yeates

Everyone with an interest in the RFC in The Great War should read ‘Winged Victory’ by Victor Yeates.
It’s a novel but Yeates served on 46 Sqn. RFC and was an ace on Camels.
The book is written as a novel with the names changed to protect the innocent (and perhaps the guilty) but the reader can tell from page one that the author was really there.

There’s a lot of detail in the book about operating rotary engines and Vickers guns. Yeates mentions ‘charging handles’ several times and the problems with interrupter gear.
This book is a must–it is the best book written about The Great War.
Go out today, buy it and spend this weekend reading it!
You’ll join Cross And Cockade by Tuesday and spend the rest of the time between now and Christmas studying the first war in the air.
Yes, I like it very much. 🙂 🙂
Cheers
Andy

That’s fascinating Whalebone.

Much of my info was started by the world-famous Biggles books. As everybode kno, Bigges was a Camel pilot in W.W.I first, but what a lot of people don’t realise was that W.E. Johns (2nd Lt, never Capt) was a very sucessful DH-4 pilot in the crack day bomber 55 Sqn – and knew a lot of the W.W.I stuff at first hand – as you can tell by reading the books. IIRC, there’s a bit about Biggles discussing “a new fusee spring which would speed up the fire of the Vickers several hundred round a minute.” – which ties back to the efforts of the chaps at Sqn level, as per your story WB! Scarff being another innivotive RFC man, inventing the Scarff ring.

Cheers

Grandfathers claim to fame as it were, was that he managed to resolve what was causing the problem and design a modification that prevented it happening which could be easily done ‘in the field’ by any competent armourer.
It was somethings as simple as altering a valve seat here, change this spring and drill a hole there etc but whatever it was it worked a treat, was evaluated at Enfield with apparently astounding results and then rapidly implemented on all aircraft fitted with Constantinesco gear.

The family used to have his original documentation and drawings, a cut away ‘gizmo’, the evaluation report, a copy of the implementation order and a very fancy medal awarded to him by the French for his efforts. These were all presented to 56 Sqn at Wattisham on the occasion of their 75th anniversary bash.
I have some photo’s somewhere, I must dig them out.

It’s stories like this that keep on bringing history back to life. What a fascinating tale Phil, thanks for sharing it. 🙂

Sadly Andy by the time my interest in aviation had become established the old boy had rather ‘lost it’ and although he lived on to a ripe old age his stories were held inside and went with him.The snippets of him I put on the forum come from my father and uncles.
The electrical system that you mention Distiller was I guess a natural progression as technology advanced.

What the hydraulic system did was in effect turn a fully automatic machine gun into a very rapid firing single shot device, with that single shot fired at exactly the right time and repeated several hundred times a minute.

One of the big problems with the early Constantinesco gear was pressure loss and leaks from the gizmo at the base of the joystick.
From memory of what my eldest uncle told me ( and he is not here to ask anymore either ) the system had to intially be primed and then kept charged by the pilot squeezing a lever on the control column.
This filled a pressure reserviour that allowed the sytem to operate.
However, when the guns were fired there was a degree of fluid ‘kick back’ from the gun mechanism and if this met an new ‘incoming’ triggering pulse from the engine side of the system the two collided inside the gizmo at the base of the joystick.
This extra unwanted pressure bled past the various flaps and valves and eventually used up all the ‘operating pressure reserve’
This resulted, in very rapid order, a failure of syncronisation followed by a slowing of rate of fire and then the guns stopping altogether.
In the heat of battle the pilot therefore had remember to keep the system up to pressure or if he forgot, to rapidly pump the system back up before he could fire the guns again.

Grandfathers claim to fame as it were, was that he managed to resolve what was causing the problem and design a modification that prevented it happening which could be easily done ‘in the field’ by any competent armourer.
It was somethings as simple as altering a valve seat here, change this spring and drill a hole there etc but whatever it was it worked a treat, was evaluated at Enfield with apparently astounding results and then rapidly implemented on all aircraft fitted with Constantinesco gear.

The family used to have his original documentation and drawings, a cut away ‘gizmo’, the evaluation report, a copy of the implementation order and a very fancy medal awarded to him by the French for his efforts. These were all presented to 56 Sqn at Wattisham on the occasion of their 75th anniversary bash.
I have some photo’s somewhere, I must dig them out.

Some pilots carried a hammer to clear stoppages, and experienced pilots would load their own ammo belts, removing bulged or misshapen cartridges.

The sequence of activity was as follows: Pushers with forward firing MG, then there were angled guns firing outside the prop arc (Bristol Scout was one) then Roland Garros fitted deflector plates to his Nieuport – they were fat metal triangles with groves on the two edges facing the gun barrel and bolted to the prop in line with the bullet track. They’d then divert the bullets off in other directions. The repeated hammer blows can’t have done the prop and engine much good! Garros was forced down over the German side, and Anthony Fokker was shown the wreck and asked to copy it. He decided to do something better and (he claimed) came up with a mechanical interupter for the Fokker Eindekker, which went on to make some of the first dogfighting aces. It’s almost certain that Fokker got an existing design and adapted it. The principle, and some early versions existed before the war, and as well as declining Dutchman Fokker’s services the British also turned down a useable interupter – not sure if it was the Consentinescu version or not.

The same question was discussed on PPrune in June here .

The Canadian Aviation Museum has a gun, engine and prop setup to show how it all worked.

Cheers!

Good stuff. I never knew of the hydraulic system. I still find it amazing that SE5a pilots used to change the Lewis drum on the upper mainplane in flight. That idea was certainly thought up by a non flyer IMHO… The mental judo applied to overcoming the problem of forward firing armament is quite amazing – look at the FE pushers for instance. Did anyone actually fit guns to the wings? If not why not? Were the wings not strong enough or was the drag penalty too great (as the wings weren’t thick enough to take a Lewis or Vickers internally)?

Hi
The Lewis gun mounting on the SE5 and 5A was known as a Foster Mount. It was devised by Sergeant R.G. Foster of 11 Sqn. RFC in 1916. It allowed the pilot to pull down the Lewis gun on a quadrant rail to change the ammunition drum.
I think the Lewis was tensioned with bungee cords to overcome gravity when pushing it back into position.
The Lewis was fired via a Bowden cable from the cockpit.
It was first installed on RFC Nieuport machines in that year, but was later used on other types, the SE5 family being the most well known.
Albert Ball certainly developed his own method with the Foster Lewis, he would pull it down on the rail and fire it upwards into the belly of an enemy aircraft while flying underneath it.

Aircraft guns were grouped together close to the fuselage on early aircraft for several reasons.
Firstly I would think they needed to be close to the centre of gravity, second the wings of early aircraft were never going to be strong enough to withstand the stresses involved with gun mountings and thirdly a crew member needed to be able to reach the gun to clear stoppages as early aircraft machine guns were so unreliable.
This practice was continued in Britain until the Hurricane was introduced. The previous RAF fighter the Gloster Gladiator still had two of it’s four guns located in such a way that the pilot could reach the breeches.
Hope this helps.
Cheers
Andy

Good stuff. I never knew of the hydraulic system. I still find it amazing that SE5a pilots used to change the Lewis drum on the upper mainplane in flight. That idea was certainly thought up by a non flyer IMHO… The mental judo applied to overcoming the problem of forward firing armament is quite amazing – look at the FE pushers for instance. Did anyone actually fit guns to the wings? If not why not? Were the wings not strong enough or was the drag penalty too great (as the wings weren’t thick enough to take a Lewis or Vickers internally)?

So what system was used on later aircraft, such as Bf109’s etc?

JC

Not sure about it, but: Wasn’t the “synchronizer” type developed in line with electrically fired ammo during the mid 1930s’? Like the Rheinmetall-Borsig MG17 and MG131?

Whalebone
despite an interest in Great War aviation stretching back many years, that’s the first (and best) description of what sounds like Constantinesco sycronisation gear I’ve heard.
Did you get the information from your Grandfather or have you found it since.
If you got it from a book, which book as I’d like to have a read about the details of the system myself.
Thanks for posting.
Andy

PS Got any stories from your Grandfather?

Very cool! Thanks Whalebone. Man…..just walking up to the plane and seeing oil on the ground would start giving me the willie’s, as in a completely depressurized/leaky firing mechanism….