"Fokker interruptors and patents": revisited

Hi all,

I'm back from vacation, and would like to address some of the postings that pertain to me. Instead of posting on the old thread, I thought I would "fire it up" again.

First of all, I want to apologize to Ed who began the thread. I don't know of Fokker taking his patent out in Holland. To the best of my knowledge his patents were made in Germany.

There has been confirmation to what "J." posted regarding "Fokker's" development of the synchronizer based on work done by Schneider and further improved by Engineer Heinrich Lubbe in the employment of Fokker. At this time, I think it would be more correct to say the synchronizer was a development of the Fokker firm, based on developmental work done by Schneider from the Euler aircraft firm, rather than the accepted "fact" that Fokker developed it on his own without assistance.

There was another synchronizer system developed by Werkmeister Hedtke at Albatroswerke, termed Hedtkesteuerung and utilized in Albatros aircraft. There is an surviving example of this system on display with two Spandaus at the Imperial War Museum.

Best,
Dave

Hi again,

In response to "John L", "J L", alias "J." concerning the question of, interrupter versus synchronizer, I think we have to remember that there are two major systems that we are talking about. I'll try to keep this simple.

I thank Mark P. for his endorsement of my work, but I don't claim to be an "expert" on all WWI machine guns, but I am very familiar with the LMG 08/15 Spandau and the "synchronizer" systems employed with them. I have not had the opportunity to personally inspect LMG 08 Spandaus and their "interrupter" systems, other than through photographs.

The first system is the Gestangesteuerung system that we commonly see illustrated in books showing a gun shooting through the prop via a linkage with a finger riding on a lobe behind the prop blades "interrupting" the firing of the gun. Actually, the gun is only being activated when the "finger" drops down off the lobes behind the prop blades. The term "interrupter" system is fitting with this system.

(A note on this first system. I am not certain if there were two things the pilot had to do to fire the gun. If there were two steps involved in shooting the gun, the first would be to engage the system of linkages with the finger contacting the lobed cam behind the prop blades, and then pull the trigger in the cockpit on the joy stick and engage the machine gun. I have studied photos of the early system and for certain I can state that when the pilot pushed the trigger in the cockpit, he was inserting the final key, of an already moving linkage system, causing the firing of the machine gun. If there weren't two steps invloved and the linkage system with the finger riding on the cam was always operating the wear would have been tremendous. I also speculate that increased motor speed may have had a detrimental effect on the operation of the machine gun by the finger being more apt to float on the lobes at high speed. This may explain some of the shooting off of props on early Fokker eindeckers.)

The latter system, termed Centralsteuerung, is totally different. Instead of the prop having a cam that interrupts the firing of the gun, the gun is activated by a gear box, (on a Mercedes, it is mounted on the back of the cam shaft housing with the tachometer drive output in the center). With this system, when the pilot pulled the trigger in the cockpit, he would engage a clutch on the gearbox on the back of the camshaft, that would drive flexible drives back to "synchronizers" on the bottom of the machine guns that would activate the trigger in the gun. (The same system was utilized in Dr.Is with rotary power plants.) By fine adjustments on the "synchronizers" the system could be set to miss the prop. I would term this system as a true synchronizer system and not a interrupter system.

I have an article that I have put together on the LMG Spandau guns that I can offer to anyone for the asking. Just send me a request, and your snail mail address.

Best,
Dave

In response to "V Bates" who wanted to know if I was in legal possession and in compliance with laws concerning machine guns, I am a class III dealer with a license to export. I have been dealing in WWI aviation guns for about twelve years. I have sold a number of them. More recently, I exported one to the Berlin Transportation Museum and a pair to Michael Carlson in Sweden for his nearly completed D.VII project. His plane will be seen in a future coming motion picture involving Göring and his post war D.VII in Sweden. I am presently in possession of eight "live shooter" Spandaus. If anyone is interested and passing through Indianaplois, drop me a line, and I'll be more than glad to give you a look. If anyone is looking for a gun, Lewis, Vickers, Marlin, Spandau, Schwarzlose, or Parabellum I can try to help out.

Best,
Dave

In response to "V Bates" who wanted to know if I was in legal possession and in compliance with laws concerning machine guns, I am a class III dealer with a license to export. I have been dealing in WWI aviation guns for about twelve years. I have sold a number of them. More recently, I exported one to the Berlin Transportation Museum and a pair to Michael Carlson in Sweden for his nearly completed D.VII project. His plane will be seen in a future upcoming motion picture involving Göring and his post war D.VII in Sweden. I am presently in possession of eight "live shooter" Spandaus. If anyone is interested and passing through Indianaplois, drop me a line, and I'll be more than glad to give you a look. If anyone is looking for a gun, Lewis, Vickers, Marlin, Spandau, Schwarzlose, or Parabellum I can try to help out.

Best,
Dave

There is a literate, but less technical explanation of the synchronizer for students at:
http://www,spartacusschoolnet.co.uk/fwwsynchronizing.
Actually, I found the site by searching "Royal Flying Corps" on the www. I am somewhat astounded that this kind of information is available to students in the U.K.
You did not address the original question of possible patent infringement that the first poster asked. Heck, I never woulda thought that a guy like Stone Cold Tony Fokker, who intimated that inventions by Reinhold Platz were his own, would have jumped somebody else's patent and claimed all of the credit; not in a million years.

Some generalities re. the issue of patents as we've recently discussed: The U. S. Government assumed the liability for any action taken by Mauser vs. Sprngfield (as re. the '03s) in the course of asking S. to ignore any patent rights of Mauser and just go ahead and tool up and manufacture the "action". The World Court levied substantial penalties against S. for which S. was reimbursed by the U.S. Government. The World Court again found against the German Navy, after WWI on behalf of (I believe) Electric Boat or whoever held many of the patents dating back to the Holland boats. I saw at one time the figures on the amount remitted by Mauser, to I belive, Vickers, after WWI as re. the number of cartridges manufacture by M. on license from Vickers. Said cartridges having been expended in a large part against British armed forces. Gives a different slant on the "What Price Glory" theme doesn't it? LEB

And don't forget that the Vickers and Spandau guns were variations of the Maxim patents.
Even the Luger Pistol and the Parabellum machine gun were based on Maxim's toggle joint breech lock.

[leo]

The Austro-Hungarian AF was late to adopt a synchronizer or interrupter system, using the baby coffin above the upper wing to house a single mg. Did the Schwarzelose present special problems in developing such a system or was this a tough technical nut for AH to solve?