I wonder why development never moved forward quickly enough in WW1, to try and attempt to mount guns on the Wings?....I mean, the SE5 had a wing mounted gun...but if Fokker hadn't cracked the Sync Gear needed..would the whole of the airwar have been fought with no forward firing Machine Gun I wonder?....I suspect, a top mounted gun (like the SE5) would have been the only alternative

One main problem must have been the load. MGs and ammo weight are heavy.
Six wing guns incl. ammo like in WW2 planes would have weighed too much.
Twin guns seemed the perfect maximum.
Now, with only max. 2 guns, and not too much ammo, you want to make sure you hit the opponent.
And the best aiming and hitting should be possible with guns on the nose, or in the prop axis.
Had Fokker not found the interrupter gear, someone else would have - maybe a British engineer.
They were all very close in developing new things, and they all had similar goals.

PS: the interrupter gear was not even invented by Fokker.
It was a German patent, but was made for a different use.
Fokker was only keen on everything he could use for his aircraft, he heard of that patent,
and he was smart enough to understand, what this device could do for him and the fighter pilots.

How's this for overkill on the guns? 2 on the fuselage and 2 on the wing.

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Actually Olham, there were both German and French patents for the system in place before 1914. Raymond Saulnier developed an interrupter gear in 1913, however the French powers-that-be saw no use for it as aeroplanes were meant for reconnaissance, not fighting. There was also the fact that Saulnier’s design relied upon the heavy and eratic firing, water-cooled Hotchkiss. If the French War Ministrey would have considered using the air-cooled Lewis instead France may well have had the first interrupter gear in use in the War.

WM, to your topic, there was also the problem of creating a wing structure in the WWI kites that would have stood up to the recoil shock of the MG's. With everything to be considered the simple solution was to mount the guns as close to the longitudinal center of the plane as possible.

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Sweet photo Jarhead. I've a hunch that kite was set up for trench strafing.

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Don't forget the Dolphin.

Standard armament was 2 Lewis and 2 Vickers mgs.
But most operated with either 2 Vickers + 1 Lewis
or just 2 Vickers.

There is a photo in Profile No 169 of a
Dolphin III with a Lewis on each lower wing, but
I think these had been beefed-up a bit.

Engine power, or rather the lack of it, was definitely a major factor when those early fighter aircraft were armed with more than two machine guns. Later in the war there were better engines available, but nevertheless the two gun setup seems to have been the optimal solution for maximizing firepower, speed and manoeuverability. It's easy to forget just how light-weight even the heaviest of WW1 fighters were compared to their WW2 counterparts. For example, a fully loaded SPAD XIII weighs something like 850 kg, easily four or five times less than a typical WW2 fighter aircraft.

SPAD XIII = full operational weight: 820 kg

Hawker Hurricane Mk. IIB = full operational weight: 3740 kg

I chose the Hurricane, because it's tail was partially wood and canvas.

Yes, that's correct and makes sense! BTW, there was case that kinda proved this which was the Sopwith Tripe which had a standard armament was One Vickers machine gun but later on some where equiped with Two Vickers machine gun but sometime after this Two machine gun armament was changed again to the previous One machine gun configuration because the weight of the extra machine gun and ammo impacted considerably on the aircraft's performance (despite adding extra firepower).

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Perhaps I've missed something here Gents, but I did not read that WM was pondering on why there weren't more guns on the WWI kites but rather why the two they had were not mounted on the wings. Am I in error on this?

That's correct Lou

Irrespective of engine power limits and wing strength, Mg's simply were not reliable enough for use on wings, always being prone to jamming. If a cowl mounted Mg jammed, the pilot could reach out with a hammer to try and 'knock' the jammed round free. If it was the top mounted Lewis, again the pilot could reach the gun to attempt to clear the jam.

Rather risky to do o when the Mg is wing mounted.

Good point

Actually, the aft was aluminum tubing with fabric covering on the Hurricane. The early models only used sheet aluminum on the forward fuselage. Later it was used on the forward fuselage, wings, and the fin, and stabilizers, with fabric covering the fuselage aft of the cockpit, and the control surfaces.

One thing too, about WWI arms, is the way guns jammed. Guns mounted away from the pilot were dead with one jam. With them mounted in front of the pilot, if a jam occurred, the pilot had a chance to clear the jam. In WWII planes, with wing mounted guns, once jammed, they were jammed. The early 4 gunned P-51 sufferred from this problem. Plus the guns have to be charged before firing, and then in the cold skies over Europe, how do you keep the guns from freezing? Especially in the cooler times of the year.

Wing construction too was a big issue. As was powerplants for aviation. Most of those old aero engines didn't use ringed pistons. They used pistons that had oilgrooves for lubrication, which effects the power output. Also, the size of the pistons were huge for the horsepower they developed. Pison rings allow for higher compression, but with higher compression, now you need a higher octane fuel, or the engine will knock itself apart over time. Like the P-38 the Italians captured. They insisted on flying it regularly, but because they used a lower octance avgas, compared to the Americans, and the British, the engines didn't last long.

There is a lot of other factors too, but I need to go and finish planting corn and beans out in the back acre.

Probably too many nagging issues in a WW1 craft for them to cope with at the time.

High drag and loss of lift with it fitted on the wing anywhere but in the middle - the wings were often thin so embedding inside the wing would likely be impossible.

There are other issues like reloading mid flight, fixing gun jams as mentioned above, and feeding the ammo - drum based would be best if on the wing, inside the wing belt-fed would need ammo storage, feeding mechanism adding more weight in the wing. Also poor access for maintenance, reloading on the ground and so on.

One main issue of the time I'd think is the extra weight, and even more weight from making the wings stronger to hold the guns and ammo.

No idea if this was the case but seems likely thinking about issues in WW1 craft already there.

The Austrians in 1916 Had an aircraft with a Vickers Type Machine Gun with its ammo, mounted on the upper wing in it's own nacelle, that might have knocked out the problem of drag. But It wouldn't help with the weight, there's just no way to get around that one. At least until more powerful engines came along, but by then the War was over

Using 20-20 Hindsight, that setup would allow incindary ammo early on