# The Synchronized Machine Gun.



## jerryw (Jan 11, 2009)

I read a copy of the book, "Flying Dutchman" by Anthony Fokker (1931) in which he devotes an entire chapter to, "I Invent The Synchronized Machine Gun".
However, I understand that Fokker's claim has been disputed in recent times. Are there any known references or discussion on this matter?


----------



## proton45 (Jan 11, 2009)

I have never heard this before...where did you hear about this?


----------



## HoHun (Jan 12, 2009)

Hi Jerryw,

>However, I understand that Fokker's claim has been disputed in recent times. Are there any known references or discussion on this matter?

He had just not been disputed in recent times, but even back in WW1.

This thread shows a 1913 patent on interrupter gear:

http://www.ww2aircraft.net/forum/weapons-systems-tech/raf-guns-ammunition-15659.html

However, the lawsuit against Fokker failed, possibly because his interrupter system would not only interrupt the burst when a propeller blade was in the way, but also continue it when the line of fire was clear again.

Fokker did however have to pay license fees to August Euler, who had patented the method of mounting a fixed gun parallel to the line of flight and aim it by flying the plane.

The designer of Fokker's interrupter gear was his employee Heinrich Lübbe, like Fokker one of the original Johannisthal aviation pioneers who was a assdious inventor whose main interest was aircraft armament (which had been the reason for Fokker to hire him).

I'd be interested in the account Fokker gives of this invention ... "Arado" by Kranzhoff has one photograph with Lübbe and Fokker standing over the cockpit of an Eindecker conducting shooting trials, and another one with Lübbe in front of an Eindecker, explaining the system to a group of aviation officers that includes Oswald Boelcke.

Regards,

Henning (HoHun)


----------



## jerryw (Jan 12, 2009)

Proton45,
Copies of "Flying Dutchman" by Fokker Gould are readily available from the the ABE BOOKS website.
The book has been reprinted many times, including paperback versions.
The 1931 editions have quite a few photos in them.


----------



## jerryw (Jan 12, 2009)

Fokker's account (see below) is extraordinarily at odds with any description of his receiving help from anyone else! He is adamant that he did the whole job on his own and in very short time!

P.S. The Patent by Franz Schneider was lodged in England in July 1913 as *No. 191316,726.* It only runs to three pages and can be downloaded free from the Espacenet website. It is written in English.


----------



## HoHun (Jan 13, 2009)

Hi Jerryw,

>Fokker's account (see below) is extraordinarily at odds with any description of his receiving help from anyone else! He is adamant that he did the whole job on his own and in very short time!

Interesting ... however, Lübbe was clearly Fokker's armament man, being made director of the Fokker-Waffenfabrik in Berlin in 1916, and he certainly was an innovative designer as he came up with a 12-barrel Gatling gun for aircraft use in 1918, and a 20 mm aircraft cannon in the early 1930s. He also held many patents on military and civilian inventions in the inter-war period.

Kranzhoff notes "The share in the remarkable profits from the production of about 42000 sets of synchronizers made it possible for him [Lübbe] to found the 'Versuchsanstalt für Waffen- und Maschinenbau' in Berlin, Potsdamerstraße 27 b in 1919". Unfortunately, he does not note if that was the inventor's share or if Lübbe had a share in the profits due to his management position at the factory producing the synchronizers.

Below the picture from Kranzhoff's book ... the German subtitle (obviously written by Lübbe's coworker Hebe) is "Fokker, Lübbe and me at the first test". It does at least suggest some close cooperation 

>P.S. The Patent by Franz Schneider was lodged in England in July 1913 as *No. 191316,726.* It only runs to three pages and can be downloaded free from the Espacenet website. It is written in English.

Thanks, I'll check it out!

Regards,

Henning (HoHun)


----------



## Marcel (Jan 13, 2009)

> Fokker's account (see below) is extraordinarily at odds with any description of his receiving help from anyone else! He is adamant that he did the whole job on his own and in very short time!



Remember, Anthony Fokker was known for his sheer arrogance and saw no trouble in using others for his own credit!


----------



## jerryw (Jan 13, 2009)

Memo to Henning,
Can you resize that photo of Fokker and Lubbe A.S.A.P., please. It is far too big for the screen! If you reduce it to about 3.5 inches, it should fit.


----------



## jerryw (Jan 13, 2009)

Below is an abbreviated version of the Schneider patent concerning a synchronized gun on an aircraft.
It is very hard to see how the Fokker "invention" differs, in principle, from this patent.
The other question is, if Fokker had thought he had invented a significant interrupter mechanism, why didn't he file a patent for it? By 1915, he was an experienced designer and manufacturer. He must have been aware of the possible wide-spread use of the device and therefore, the importance of protecting his rights by patent.
Also worth noting that Schneider's patent lists his location as "Johannisthal near Berlin", the same place that Fokker spent a lot of time during his early flying days.


----------



## Marcel (Feb 2, 2009)

This is what happens if the system fails. A propeller from a Fokker D.XVI in the Dutch Airforce museum, Soesterberg


----------



## HoHun (Feb 2, 2009)

Hi Marcel,

>This is what happens if the system fails. A propeller from a Fokker D.XVI in the Dutch Airforce museum, Soesterberg

Great illustration, thanks a lot! 

One version of Immelmann's death is that his aircraft crashed after a malfunctioning synchronizer gear shot up his propeller, so it seems that this was a realistic danger. (I presume the worst case would be one blade being torn off, as the resulting imbalance would probably destroy the aircraft.)

Regards,

Henning (HoHun)


----------



## Ferdinand Foch (Feb 3, 2009)

Whoa, thanks for the picture Marcel, I would have hate to have been the pilot for that aircraft. Dumb question, though, how (or if they did at all) did the Allies learn to use the syncronized machine gun themselves. Did they invent it on their own, or did they design theirs off of machine guns from captured German planes. Just curious.


----------



## Marcel (Feb 4, 2009)

Well, I think the pilot was incredible fortunate not to shoot his prop off. I think it was a very short burst 
I thought I read somewhere that they copied it from a captured E.III


----------



## Avn-Tech (Feb 7, 2009)

Group,

I am sure that several people working independently on a problem would come to about the same conclusion. Hence more then one person could rightfully clain to have invented the interrupter gear and be legimite claim.

Remember that when Folker claimed to have invented the gear, WW I was going on and the government probably seized the rights for their use (So no patents).

Also remember that information did not travel as fast in early 1900's as it does today. So an invention in Europe may not reach america for a while.

When I first went into the Air Force, I had a Squadron Commander whose father invented the Cleco. He received no compensation since it was wartime, and then country need the invention.

Laterrrrrr
Avn-Tech


----------



## Deanimator (Jun 30, 2009)

There were several synchronization systems which predated Fokker. Their problems were that they were usually coupled with guns that were difficult or impossible to synchronize by ANY system. The book "Flying Guns" goes into extensive detail on synchronization systems and why some failed and others succeeded. 

Basically, closed bolt, short recoil operated guns are easy to synchronize because the timing of the firing cycle is highly predictable and consistent. Open bolt, delayed blowback, and similar guns are hard to synchronize because of inherent firing delays caused by lock time and bolt travel before a round is fired.

Easy to Synchronize:
Maxim based systems (MG08, MG08/15, Vickers, Russian Maxims, etc.)
Browning/Marlin
Browning M1919

Hard or Impossible to Synchronize:
Schwarzlose
Revelli
Lewis
Hotchkiss


----------



## siznaudin (Jul 13, 2009)

At Le Bourget (their WW1 section is superb!)


----------



## Marcel (Jul 14, 2009)

Great pictures, siznaudin. Were those the propellors used by Roland Garros?


----------



## siznaudin (Jul 14, 2009)

Marcel said:


> Great pictures, siznaudin. Were those the propellors used by Roland Garros?



I can't recall that there was an explanatory plaque of any type, let alone a claim that it came from Roland Garros' aircraft. Perhaps it was of the type which was used by Garros? No doubt if such an item went to public auction the claim for that might well be made


----------



## Milosh (Oct 31, 2009)

HoHun said:


> Hi Jerryw,
> 
> 
> 
> ...



A motor driven rotary 12 barrel mg of the Fokker Waffenfabrick directed by Lubbe,






edit. from Arado: History of an Aircraft Comapny ISBN 0-7643-0293-0


----------



## The PIPE (Dec 13, 2009)

Dear JerryW HoHun:

The PIPE Here again...and where I'm interested in eventually, and VERY accurately (for the very first time, anywhere), as an RC Giant (1/4th sized) Scale flying model, replicating Leutnant Kurt Wintgens' Fokker M.5K/MG, with IdFlieg serial number *E.5/15*, the very first aircraft to ever score a victory with a synchronized machine gun on July 1, 1915, I've taken a HUUGE interest in how the idea of the synchronized machine gun got started, and its very first successful engagements.

I've been a LONG time member of Leo Opdycke's WW I AERO, and a number of issues of that fine magazine in the past had a three-part article in them authored by the late Canadian aviation author, Hank Volker, that concisely detailed the whole history of forwards-firing automatic weapons on fighter aircraft.

The articles can be found in these back issues of WW I AERO...

*WW1 Aero No.137 (August 1992) pgs. 42-61 Part I Synchronizers: firing through the prop: origins - a historical survey

WW1 Aero No.138 (November 1992) pgs. 74-83 Part II Synchronizers: firing through the prop: machine-gun synchronizers and "interrupters"

WW1 Aero No.142 (November 1993) pgs. 47-62 Part III Synchronizers. Firing through the prop: automatic guns for synchronizers. *

I've found my copies of issues 137 138, but a GOOD bit of cleanup around my house needs to be done before I'm likely to find my copy of issue No.142 !!!

Hank mentions the roles of August Euler, as being THE person to first patent the idea of a forward-firing machine gun of any sort on an aircraft, of Franz Schneider, and even the Siemens-Schuckert firm, who apparently pioneered the idea of using an electrical link to do the gun synchronization with.

Tha article series also covers Garros' armored, "wedged" propeller, and why the Kaiser's military couldn't get it to work for their needs.

If one also wishes to get an even MORE complete picture of how the whole deal unfolded over time, the Windsock Datafile No.91, on the Fokker E I and E II aircraft, also has even more info on the details of how the gun synchronizer got into service with the Luftstreitkräfte, and mentions prminently how one Leutnant *Otto Parschau* was a critical personage in its development, as well as Kurt Wintgens, the first pilot to ever get a victory with it.

The Osprey "Aircraft of the Aces"-No.73, "Early German Aces of World War I", has some of the same info, but also has other items not mentioned in the Datafile...taken together, along with Hank Volker's articles (for which some of the historical info IS "updated" by the Datafile and Osprey books) would seem to provide about the clearest "picture" ever seen to date on HOW Fokker's _Stangensteuerung_ pioneering gun synchronizer got into service in the first half of 1915, and how things got going for the Kaiser's fliers in starting the "Fokker Scourge" that the Nieuport Bébé and Airco D.H.2 started to overcome as 1916 wore on.

Yours Sincerely,

The PIPE!


----------



## bruno_ (Dec 26, 2009)

Hi Pipe,

I'm interested in some technical aspects related to WWI Aircrafts synchronizers.

What I'm looking for, are two basic data: 1) How many firing pulses per propeller turn and 2) the amplitude of the "percussion" angle", the different devices featured. Of course, the easiest to find out should be the first one, while the second parameter is something that had to/could be adjusted within a certain range, depending on the actal application and, usually, is far more difficult to retrieve. Anyway, while the meaning of the first number is "sel explainining, the secondo parameter described how large the firing angle (refferred to the propeller disc) linked to the single firing pulse was. That is, if the percussion angle was, say 20°, the shot enabled by the firing pulse (provided the weapon was again ready to fire) could be fired within this angular interval.
As to the number of firing pulses, since the synchronizer could be driven by the propeller (direclty or, i.e., via a couple of gears) or by some other device belonging/driven/linked to the engine (camshaft or something like),the number of pulses associated to the synchronizer could be refferred to the propeller turns or to the engine turns or to something different (i.e,its own dirving shaft), depending on the actual device operating and connecting mode. Anyway, by knowing the actual ratio between the propeller turns and the turns of the device driving the synchronizer, it is (was) possible to get anyway how many firing pulses per propeller turn the device was able to generate. In the same way, it is possible to get the number of fiiring pulses per engine turn.

Both parameters were fudamental in onder to get the actual synchronized rate of fire as a function of the engine speed, to set up the device with respect to the prop blades and to state the engine speed range for a safe shooting. Of course, all this stuff, in combination with the knowledge about weapon/cartridge(s) techincal and ballistic features and the actual mounting of the weapon with respect to the propeller "disc".

But coming back to historically relevant devices, one of the most interesting device (at least for me) is the Alkan-Hamy since, as far as I know, this was the device employed on Ni17 and (maybe) on the Hanriot HD1. It would be nice to get at least the info about the firing pulses per prop turn since, if I'm not wrong, the cam(s) driving the device was (were) placed on the rotary engine (i.e. the propeller shaft) so that their number should give immediately the info I'm looking for. What would actually be interersting is to know if the magci number was just 1 firning pulse per prop turn or just the double of it or, maybe, early version featured 1 and later versions had two cams rahter than just one.

Have you the info I'm looking for about this device, in particular, and or to some other of the many synch gears pioneering the era of firing through the propeller disc? Or at least, could tell me where to search for?
Up to now I wasn't able to find anything "sure" about this device, in sipte of my long lasting search on books and/or internet sites.

Thnaks in advance (to you and or to everybody could give me useful data on this subject)


----------



## The PIPE (Dec 26, 2009)

Dear Bruno:

The PIPE Here again...happy holidays, by the way, as a BIIG sporting event in my neck of the woods takes place on New Year's Day, as mentioned at 2010 Bridgestone NHL Winter Classic - Flyers v. Bruins , with my favorite sports team taking part against a huuge rival of theirs from Philly...and it's one that's FAR better than any of the college sports taking place that day, IMHO...

...I'd thought I'd start this reply by stating, where machine guns HAVE been described as "VERY deadly single-stroke engines", as a type of "internal combustion engine", getting the internal combustion engine that spins the prop to "synch-up" with the single-stroke "fatality engine" that is mounted on the fighter, to get it to do ITS main job, is the whole _raison d'etre_ for the gun synchronizer's existence in the first place.

Right now, I've got my copy of WW I AERO issue no. 138 right in front of me as I'm tyiping this text, and from section 2.5, entitled "Description of a Typical Synchronizer" from part 2 of Mr. Volker's article, I quote Mr. Volker, with my additions for clarification in [brackets] within the text, as I always do in such a situation:

"In a Maxim-type machine gun, such as the 7.92mm calibre lMG 08 [machine gun], with each firing of a round the lock assembly inside the gun traveled rearward, carrying the trigger mechanism, including the trigger arm and the firing pin with it. It then returns forward to complete the cycle of operations. Therefore, the pulsating output-end of the synchronization could act on the trigger arm on the lock assembly only when it had returned to the firing position; that is, when it was held against the breech face of the gun barrel with the firing pin cocked. The rate of fire generated and controlled by the synchronizer and the gun [it controlled] in this manner varied with propeller speed, [which draws out a sawtooth curve when graphed with the horizontal axis showing prop speed, and the vertical axis showing the rate of synchronized fire]. Since a [machine] gun operating in conjunction with a synchronizer was capable of producing single shots only, in response to impulses generated by the synchronizer, it was actually made to function as a semi-automatic gun, also known as a self-loader, instead of a fully-automatic machine gun".

So "there you have it" from Mr. Volker himself...generally only ONE bullet got fired from a Fokker E.I's single Spandau gun from a single complete rotation of the propeller and its "umlaufmotor" ("rotary engine" im Deutsch).

I suppose a synchronizer COULD be driven off any rotating component of the engine that was essentially operating at the same exact speed of the prop, or at a proper "whole number integral" speed in relation to the prop (like an inline engine's camshaft, rotating at 1/2 the speed of the crankshaft). With a rotary engine-powered aircraft like the Eindecker, the rear end of its umlaufmotor's spinning crankcase is where the synchronizer's trigger cam would have been mounted.

And, if using the original _Stangensteuerung_ system format from the Eindecker, one cam per machine gun would most likely be needed for twin-gun installations. The Albatros firm came up with their own system, initially, for their D-series fighters, as one example of a non-Fokker synchronizer showing up at the Front, with the Allies' Vickers-Challenger system being a first step for the eventual winning side, as the Constantinesco unit became the most-widely used synchronizer during WW I for the Allies, if my mind serves me properly.

You CAN get reprints of the Hank Volker three-part article from WW I AERO, just by contacting them though their page for it at World War 1 Aeroplanes, Inc.-Contact Us ...I'd strongly suggest you get a copy of the entire three-part article for yourself, so then you can understand the whole issue of gun synchronization quite a bit better.

The Osprey and Windsock Datafiles are also good references to use alongside the article by Mr. Volker...so those might be a good idea to get, to look at the WHOLE picture of how the gun synchronizer began to evolve almost a century ago.

Hope you can get copies of that complete article from WW I AERO...

Yours Sincerely,

The PIPE!


----------



## bruno_ (Dec 26, 2009)

Dear The Pipe,
thanks a lot for quickly anwering my post . I've appreciated your analogy between the internal combustion engine and a rifle or a machine gun! The ICE too is a semi-automatc system once the injection and ignition system are properly synchronized wth piston etc stuff.
For sure I'll follow your hint to get in touch with people you suggested. Getting the papers on the subject is anyway a good idea especially if I will find there data I'm looking for.
But, in order to make more clear and possibly more fruitful my search, please, allow me to explain that the "principia" behind the synchronization are clear to me (at least so they seem to me) and, indeed, once I get the two parameters I spoke about in my previous post, it would be easy to produce Rate of Fire vs engine speed graphs for any aircraft (engine+prop)/weapon/cartridge set. Clearly, once some few other basic info about the trio are known.
The "sawthoot" aspect of such graphs is the basic "ideal" "universal" form and, for an ideal enabiling (possibly firing) pulse, it is also the "exact" form in any engine (propeller) speed range, provided the enabling angle (the percussion angle) tends to zero. In this case, the linear growth and the sudden down aspect, repeated whenever the frequency of enabling pulses is equal to or is an exact multiple of the weapon "natural" (unsynchronized) rate of fire is quite straightforward to get. The graph shows a vertical drop from the "full" natural rate of fire to a local minimum that increases as the order of multiplicity increases according to the N/(N+1) law, where N is the order of multiplicity between the frequency of enabling pulse and the gun natural rate of fire. Engine speeds (critical speeds) corresponding to these "situations" are easily calculated once some basic parameters are known.I.e: the number of firing pulses per prop turn and the ratio between prop and engine speed (but this is not the only way to get the same results). Same reasoning for the link between Rate of fire and prop speed.
Things are a little bit more puzzling if the amplitude (in terms of angle and, consequently,of time) of the enabling pulse is different from zero, as usually happened in actual systems. Basically the sawthoot aspect is still there but in the area of the crritical speeds, the drop of the rate fo fire will be no more vertical. Its behavior will be more complicated. The reason why I'd like to get info about percussion angle too (i.e. to produce more accurate graphs) should be more clear now and I really hope to get a better insight into the "raw" data" of the synchronization systems of WWI aircrafts so to complete my quantitative understanding about their behavior.
Finally let me explain why I'm so interested in Alkan-Hamy gear: Ni 17 and Hanriot HD1 equipped a lot of squadriglie of the Italian Air Force during the WWI and Italy is my Country 
Thanks again!


----------



## beaupower32 (Dec 29, 2009)

Intresting read guys, I have always wondered how these guns work. Thanks for sharing.


----------

