I was just watching a Hanna Barbarra cartoon. The evil Snidely Whiplash and his sort-of evil snickering dog Mutley are in a batwinged bi-plane persuing Captain Cave Man (whos flying a boulder and log bi-plane, explain the aerodynamics of that!), anyway Snidely Whiplash gets tha Cap’n in his crosshairs, fires his machine gun and promptly saws his propeller blades off.
It occured to me that probably really was a problem during WWI. Fast as the propeller may spin, you’ll still probably hit it occasionally. The props were too big to place the guns ABOVE them and still accurately fire them, right? Did they just keep an awful lot of replacement props?
Actually shooting off your own propeller was a bit of an issue. That’s why early guns were fitted on the top of the wing, but as one would suspect they weren’t as accurate. The key development was hooking a cam to the propellor that would provide the energy to fire the gun. The cam could then be synchronized to fire the gun only when the propellor blades were out of the way.
originally, the planes could not fire forwards - they were just used for observation, or had a gun for the observer to shoot (not very accurately). In fact, I think in the very early days of the war, they even just dropped rocks over the side of the plane.
the first step to more satisfying aerial carnage was some bright daredevil who put a metal plate on the propellor, strong enough to deflect the bullets that happened to hit the prop. this was pretty risky, what with the chance for ricochets, plus the strain it would place on the prop. i believe he was captured somehow, but it put the fear of god into other pilots for a while.
then came the interrupter - the prop and the machine gun were synchronized, so that the machine gun’s fire was interupted at the moments in the cycle when the bullets would hit the prop - given the high rpm of the prop and the high rate of speed of the gun, this was technically difficult, but do-able. I think the Germans came up with it first, but it was quickly copied, and the dog-fights were on.
(can’t give you any cites for the above, as I read it in high school - would defer to anyone with more detailed/reliable knowledge.)
It seems to me that the first such biplane machinegun was called the Louis gun (named after the inventor). The machine gun and propeller were linked/timed as others have posted. It really wasn’t that complex. The machinegun was only able to fire when the propeller was in particular positions (actually, it was prevented from firing when the propeller was in particular positions. IIRC, it worked by the propeller “turbine” hitting little switches).
I tried doing a search in another window, but I am getting really lagged. I’ll try later and if I find a site I’ll post it.
What more could you expect from somebody who lets people kick him to the head?
Roland Garros came up with the idea of putting steel wedges on the backs of propellers. (He used soft-nosed ammo to make it easier to dissipate the force of the bullet hitting the prop.)
Having shot down 5 planes in about two weeks, he cleared the German observer aircraft from the skies in his section of the front. So then he was sent to bomb a railroad yard far behind German lines. His bombs were hand-held, small, and innacurate. More importantly, his engine quit during the bombing run and he had to coast in for an emergency landing–at which point he was captured.
The Germans showed the plane to the Tony Fokker, Dutch guy who was building their best planes, and ordered him to fit his planes the same way. As an engineer, Fokker was put off by the inelegance of Garros’s trick, thought it over, and invented the interrupter gear.
(Two years later, Garros escaped from his POW camp and made it back to France. Ignoring the fact that the planes had improved in speed by more than 80% and that agility and tactics had followed suit, he talked someone into letting him take a plane back into the action–and was promptly shot down by a (trained) German beginner.)
BTW, the wedges Garros put on his propeller do not seem to have been used by anyone else (which is why the Nieuports and early Sopwiths had the top wing-mounted gun). No one is sure whether the French (and English) simply didn’t know exactly what he had done (it was a field modification that he had done, personally) or whether they feared he had a patent on the idea!
Garros was not the first one to arm a plane. Several “pusher” types (with the engine behind the cockpit) had swivel-mount machine guns for the observer that could fire forward. Garros’s invention, hover, allowed the pilot to aim the whole plane, improving accuracy to a lethal level.
Not exactly.
The Lewis gun was the standard British machine gun in the early part of the war. It was cranky and subject to jamming with an ammo drum that was very difficult to change while flying.
Eventually, the British high command gave up and actually ordered the far superior Vickers machine gun.
The French used Lewis and (before the British) the Vickers. They also had some (American-designed) Hotchkiss guns, but I don’t think they were used, much. (Garros had used a Hotchkiss for his experiment.)
The Germans, of course, used the very reliable Spandaus.
FrankDs got a point, The real Snidely Whiplash wasn’t Hanna Barbarra, but this charactor had a real Snidely vibe about him. Anybody got the poop on him? He always flew with muttley in the “Laff-O-lypics”?
For more on Roland Garros, aviator and national hero in France. The page is from the French Open web site, which has its final played at Roland Garros Stadium.
You guys have pretty much answered this question, but I’d like to add an interesting bit of trivia. The sort of coughing sound you here sometimes in dogfights is specific to synchronized machineguns. The gunfire is cut off every now and then, and starts up almost immediately. If the guns were wing mounted, it should be a steady beat or buzz.
I was reading about Anthony Fokker. Apparently after he designed an interruptor the Germans wanted him to test it out in combat, not caring that, as a Dutchman, Fokker’s participation in the war would be a crime (neutrals aren’t supposed to shoot people). Fokker took the device up in a plane, lined up a French plane in his sights, and thought the better of it. He was willing to design planes for the Kaiser, but not pull the trigger.
There’s also a bit of myth about the actual design of the synchronization gear. One side of the camp claims that Fokker saw Garros’ plane, retired to his room, and had an interruptor gear designed the next morning. The other group claims that Fokker already had the design prepared.
Few people have pointed out that the first machine guns designed by Gatling are based on the very premise of an interruptor. They have multiple barrels that are turned into position by a crank. When the barrel is lined up correctly with the breach, the gun is automatically fired. Fokker’s design is not too terribly different. It lines up a firing notch on the propeller shaft (or sometimes on the engine itself if the motor spun) and allows the firing mechanism to activate only when the shaft is in a particular position, just like the crank on a Gat.
In re synchronized propellors: For old Mad fans (of its early comic-book format), consult the story “Black and Blue Hawks!” to see what happened when Boss Hawk tried to fire the blunderbuss mounted on the sputtering biplane piloted by “Chop Chop Chop.” (I leave it to others among the Teeming Millions to divulge the outcome of this.)