Planes and Choppers Photos - Pictures of Aircraft and Helicopters

Picture No:

1333

Courtesy of:

Jorge A. Dietsch, "Wings Photo Images"

Year:

2006

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WW I Triplane Fokker Dr.1

Photo of N113PC Fokker Dr.1, 1982, "Dreidecker", (Replica). Photo @ Chino AP, CA. May 19-2006.
Picture Added on 11 January 2007.

Comments

It's weird to see the guns mounted. I hope that they didn't shoot their own propeller off :-).
Added by Mars. on 13 January 2007.

There is no mystery about a machine gun firing through a propeller without hitting the blades. Nearly everyone understands the principle by which the valves of a gasoline motor are timed so as to open and close at a given point in the revolution of the engine. In the same way a machine hgun may be timed to shoot. On the end of the cam shaft of the motor is plaved an additional cam. Next to this is a rod connected with the breech block of the gun. When the gun is not being fired the rod is held away from the cam by a spring. pressing the trigger brings the two in contact, and each time the cam revolves it strikes the rod which in turn trips the hammer of the gun and causes it to fire. The cam is regulated so that it comes in contact with the rod just as each blade has passed the muzzle of the gun which can therefore fire at this time only. The engine revolves at least 1, 000 turns per minute and as there are two chances for the gun to fire for each revolution, this would allow the gun to fire 2, 000 shots per minute. The rate of fire of a machine gun varies from about 400 to 1, 000 shots per minute according to the type of gun and the way in which it is rigged. The gun therefore has many more oppurtunities to fire between the blades of the propeller than its rate of fire will permit it to make use of. Consequently, the gun can work at full speed regardless of ordinary variations in the number of revolutions of the engine.

source: www.militaryphotos.net/forums/showthread.php?t=109581
Added by Arthur van Gansewinkel on 22 August 2008.

Interesting thank you, confused still.
All the best Andrew.
Added by Andrew Wright on 26 August 2008.

Put a different way, the gun is prevented from firing each time a propeller blade passes in front of it. This is achieved by a mechanical linkage between the engine cam shaft and the gun. The gun therefore "knows" via the engine when a propeller blade is in front of its barrel, and stops firing for that fraction of a second.
Added by Peter John Langsdale on 26 August 2008.

Very advanced really for the time these aircraft where designed and built, who were the first to achieve this?
Andrew.
Added by Andrew Wright on 26 August 2008.

No matter the speed of the props.
In fact, it is a rather simple solution to a seemingly difficult matter.
Added by Arthur van Gansewinkel on 26 August 2008.

Andrew,
Please have a look at the following links.
Hope it will help you.
Greetz, Arthur
www.greatwar.co.uk/westfront/ypsalient/secondypres/prelude/garros.htm
www.chara.gsu.edu/~lewis/bard/vera/vera0005.html
www.militaryphotos.net/forums/showthread.php?t=109581

Added by Arthur van Gansewinkel on 27 August 2008.