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Odin_Part_2
04-23-2008, 04:08 PM
Don't you ever think to yourself:

"I Sure Hope I Don't Shoot Away My Prop Blades As I Shoot These Machine Guns That Are Mounted in My Fuselage"

I remember reading how they did that in World War I, when this first got started, about the Sychronisation of the Engines Variable Pitch & the way that the bullets came out and zipped past these little chutes that were placed on either side of the Prop Blades or something like that.

Would anyone care to explain this to me in more detail where a lot of big words are not used so I can understand just what it is that you are trying to explain to me & others who might also wonder about the same thing from time to time?

Odin_Part_2
04-23-2008, 04:08 PM
Don't you ever think to yourself:

"I Sure Hope I Don't Shoot Away My Prop Blades As I Shoot These Machine Guns That Are Mounted in My Fuselage"

I remember reading how they did that in World War I, when this first got started, about the Sychronisation of the Engines Variable Pitch & the way that the bullets came out and zipped past these little chutes that were placed on either side of the Prop Blades or something like that.

Would anyone care to explain this to me in more detail where a lot of big words are not used so I can understand just what it is that you are trying to explain to me & others who might also wonder about the same thing from time to time?

VW-IceFire
04-23-2008, 04:12 PM
I always thought the WWI mechanism was simple. The trigger on the machine gun(s) was fitted to a cutoff system and the cutoff system spun with the prop. So if the prop was in the way of the machine guns then the interrupter cut off the trigger and the gun stopped firing.

I think it got a little more sophisticated in WWII. Some German planes had electrically fired guns (FW190?) and the interruption system was also electronic. Not sure of the specific details ...would be interesting to know more.

ImMoreBetter
04-23-2008, 04:31 PM
http://upload.wikimedia.org/wikipedia/commons/archive/1/19/20050325063512!Interrupter_gear_diagram.png

That little bump on the cam wheel interrupts the gun. The bump is timed so that the gun is interrupted as the prop goes by.

Stoner_109
04-23-2008, 04:39 PM
Shouldn't there be 3 bumps then?

PF_Coastie
04-23-2008, 04:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Stoner_109:
Shouldn't there be 3 bumps then? </div></BLOCKQUOTE>

No, it just rotates once for each blade.

ImMoreBetter
04-23-2008, 04:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Stoner_109:
Shouldn't there be 3 bumps then? </div></BLOCKQUOTE>

Yes, as many as there are prop blades. It's just not illustrated by the diagram.

DIRTY-MAC
04-23-2008, 05:15 PM
tha first wersion, just had a metal plate at the back of each blade, and the bullets would just ricochette off them


Garros, a pre war aviator, brought the next advancement in militarized aeronautics. Garros had heard of attempts to attach a machine gun to the speedy single-seater N monoplane. He devised a scheme in which he would place a metal deflector plate on the propeller in front of a Hotchkiss (fig. 1) machine gun. Thus he would be able to fire a machine gun through the propeller without damage to his machine, "because the gun was close to the pilot he could fire, reload, and fix jams very easily" (Ricken). All of this plus the fact that the gun was attached to speedy plane able to maneuver with ease unlike the slower less maneuverable two passenger planes. Garros had great success with his invention getting his first kill in February of 1915 (Funderbunk). Garros made air combat possible in better suited planes allowing him to gain an advantage over the Germans.

Tony Fokker, an aviator and plane builder for the Germans, took over where Garros left off after Garros was captured behind enemy lines. Once Garros's plane was captured, it was sent to Fokker to be analyzed and replicated. The Germans wanted a plane that could fire through the propeller as well. However, Fokker found that Garros's method was very ineffective and that the only way to gain an advantage would be to have a gun and propeller synchronized. Thus no longer needing the deflectors on the propeller, because the gun would only fire in the gaps of the propeller. The "Fokker Scourge" began in 1915 because of the superiority of the new synchronized machine gun attached to the Fokker Eindecker (Reynolds). The Allied side took heavy losses for the next few months because they were without Fokker's ingenious technology.

Odin_Part_2
04-23-2008, 05:27 PM
I really hate to say this, but I still don't get it.

The Props on my Fw-190 are rotating at 9,000,000 revolutions a second, so how in the freaking hell do my machine gun bullets NOT chew the hell out of my Prop Blades?

Unless of course you're saying that the speed of the blades rotating is faster than the speed of the bullets coming out of the machine......

Now wait, that doesn't make any sense either.

It doesn't matter if my guns are stationary or if I'm standing in the Cockpit spraying from side to side with a Schmeiser, I'm still gonna hit the blades, right?

halfcool
04-23-2008, 05:35 PM
Sorry, but I thought you said that your propeller blades go 9 million revolutions in one second. Pardon me for asking, but what kind of plane are you flying?

Lurch1962
04-23-2008, 05:43 PM
Even without the interrupter only some 1 in 6-ish bullets would strike the prop. (Compare the ratio of prop width to gap between blades at the radius at which bullets pass.)

Furthermore, compare the linear speed of a bullet vs. prop circular velocity, and you'll find that the bullet is faster. So from the bullet's point of view, the prop is moving relatively more slowly.

As is obvious, it only remains to block the firing of those 1 in 6 which would otherwise hit, and that's not a difficult engineering problem at all.

Odin_Part_2
04-23-2008, 06:09 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by halfcool:
Sorry, but I thought you said that your propeller blades go 9 million revolutions in one second. Pardon me for asking, but what kind of plane are you flying? </div></BLOCKQUOTE>

An Fw-190, remember?

Doode, that was an exagerated example to go with my question.

Odin_Part_2
04-23-2008, 06:11 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Lurch1962:
Even without the interrupter only some 1 in 6-ish bullets would strike the prop. (Compare the ratio of prop width to gap between blades at the radius at which bullets pass.)

Furthermore, compare the linear speed of a bullet vs. prop circular velocity, and you'll find that the bullet is faster. So from the bullet's point of view, the prop is moving relatively more slowly.

As is obvious, it only remains to block the firing of those 1 in 6 which would otherwise hit, and that's not a difficult engineering problem at all. </div></BLOCKQUOTE>

That's easy for you to say.

I think I'm gonna stick to shooting you guys down with My 88mm Anti-Aircraft Guns.

Arrowhead2k6
04-23-2008, 09:09 PM
It's amazing how ingenious people can be when there's some killing to be done. -_-

bhunter2112
04-24-2008, 12:14 AM
What about a hang fire?

luftluuver
04-24-2008, 01:21 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Odin_Part_2:
I remember reading how they did that in World War I, when this first got started, about the Sychronisation of the Engines Variable Pitch & the way that the bullets came out and zipped past these little chutes that were placed on either side of the Prop Blades or something like that. </div></BLOCKQUOTE>

What is this <span class="ev_code_YELLOW">Engines Variable Pitch</span>?

Google is your friend

Major Charles J. Biddle, described the principle of the synchronized machine gun.

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.
http://www.wwiaviation.com/early_dev.html

ImMoreBetter, the Canadian Aviation Museum has an operating display (no bullets) of your diagram.

Odin_Part_2
04-24-2008, 06:29 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by luftluuver:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Odin_Part_2:
I remember reading how they did that in World War I, when this first got started, about the Sychronisation of the Engines Variable Pitch & the way that the bullets came out and zipped past these little chutes that were placed on either side of the Prop Blades or something like that. </div></BLOCKQUOTE>

What is this <span class="ev_code_YELLOW">Engines Variable Pitch</span>?

Google is your friend

Major Charles J. Biddle, described the principle of the synchronized machine gun.

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.
http://www.wwiaviation.com/early_dev.html

ImMoreBetter, the Canadian Aviation Museum has an operating display (no bullets) of your diagram. </div></BLOCKQUOTE>

It was nothing, don't worry about it, just me trying to remember what I read when I was like 8 or something.

I'm surpirsed I even knew how to spell those words at the age of 8.

It's still too complicated for me to aprehend.

An extra cam with a bump on it that triggers this bar that pulls the trigger allowing the machine Guns to shoot between 400 & 2,000 rounds in a minute with the props spinning at 1,000 revolutions per minute, guns shoot, props turn, guns, props, props, guns, ARRGGHHHHHHH, I'm going down in flames, I shot myself down again!!!!!!!!!!!!!!!

AND I DIDN'T REMEMBER TO BRING A PARACHUTE THIS TIME EITHER!!!!!!!!!!!!!!!!

Why didn't I listen to my mother & just stick with the Anti-Aircraft Artillery?

Daiichidoku
04-24-2008, 06:45 AM
from wiki, on Garros's deflector plates:


Experimentation with gun synchronization had been underway in France and Germany before the First World War but the engineers involved received little support or encouragement from the military who disregarded the need for armed aircraft, believing them solely useful for reconnaissance. Swiss engineer Franz Schneider, working for LVG, designed and patented a synchronizer in 1913. French aircraft designer Raymond Saulnier built and patented a practical gun synchronizer in April 1914, having borrowed a machine gun from the army for testing. No design was developed to the point of being operational in the field, one significant problem being the inconsistency of ammunition propellant resulting in hang fire rounds.

Saulnier pursued a simpler method using armoured propeller blades. In December 1914, French pilot Roland Garros approached Saulnier to arrange for this device to be installed on his aeroplane but it was not until March 1915 that he took to the air with a forward-firing Hotchkiss 8 mm (.323 in) machine gun mounted on his Morane-Saulnier Type L. In addition to the armoured blades, Garros's mechanic, Jules Hue, attached deflector wedges to the blades. While this reduced the chance of a dangerous ricochet, the wedges diminished the propeller's efficiency. On 18 April 1915, having shot down three German aircraft, Garros' plane was forced down in German territory. Before he could burn his aircraft, he was captured and the gun and propeller were sent for evaluation by the Inspektion der Fliegertruppen (Idflieg) at Döberitz near Berlin.



oh, and Fokker's a Fokker

Popular accounts claim that Dutch aircraft designer Anthony Fokker was then asked to reproduce Saulnier's deflectors and proceeded to invent the synchronization system in a matter of days "” according to some accounts,[attribution needed] Fokker was given the problem on a Tuesday evening and presented a working system on Friday. However, Fokker's team, including engineer Heinrich Lübbe, had been working on a synchronization mechanism since late 1914, probably based on Schneider's patent. Indeed in 1916 LVG and Schneider sued Fokker for patent infringement "” the battle continued until 1933 and though the courts repeatedly found in Schneider's favour, Fokker refused to acknowledge the rulings.



dont forget CC gear , also

superior hydraulic Constantinesco synchronization gear (or "CC" gear, invented by Romanian engineer George Constantinesco) which used impulses transmitted by a column of liquid instead of a mechanical system of linkages. This was not only inherently more reliable, but delivered firing impulses at a much higher rate, so that a synchronised gun now fired at more or less the same rate as a normal machine gun, regardless of engine revolutions. The gear could also be easily fitted to any type of aircraft instead of having to have type-specific linkages designed. The Constantinesco gear remained in use with the Royal Air Force until the Second World War, the Gloster Gladiator being the last British fighter to be equipped with it.

Col.BBQ
04-24-2008, 04:44 PM
Quite simple, Odin. Next time you fly your Fw-190, keep the engine shut off, on the ground preferably, and look how much space there is in the arc between the blades. All the electrical interrupter in the Fw-190 had to do is to be timed for the bullets to shoot into that huge space. Although it wasn't uncommon to see planes returning to base with damaged props due to misaligned or faulty interrupters.