New member - basis questions

[Harold]

Hello. I've taken a strong interest in fighter planes due to watching the recent "Dogfights" programs on the History Channel. I've got some questions about the planes that I haven't been able to find answers to:

* What is the difference between a machine gun and a cannon on a fighter plane? Is it just the caliber of the shot? Does a cannon always fire an explosive shell, while a machine gun never would?

* Is there a general rule as to which type of gun (machine gun or cannon) would be mounted in a fixed position and which type would be able to swivel? I know a machine gun would have to be able to pivot. Otherwise the pilot would seem to be very limited as to when he could shoot.

* Its seems, from watching the TV programs, that the big danger in dogfights was having the enemy get on your tail where you are most vulnerable. Were there any fighter planes in WW11 or other wars which had a co-pilot sitting behind the pilot facing backwards in a plane that had guns facing backwards as well. The co-pilot would have a back window to look of. A plane wouldn't seem to be such a sitting duck if it could fire at an enemy directly behind it.

Thanks to anyone who cares to comment. Harold.

[syscom3]

* What is the difference between a machine gun and a cannon on a fighter plane? Is it just the caliber of the shot? Does a cannon always fire an explosive shell, while a machine gun never would?

Generally, a cannon shell is explosive in nature and is larger than a MG bullet. It is considered to be more destructive than a MG, but that is at the expense of a slower rate of fire and a slower muzzle velocity.

* Is there a general rule as to which type of gun (machine gun or cannon) would be mounted in a fixed position and which type would be able to swivel? I know a machine gun would have to be able to pivot. Otherwise the pilot would seem to be very limited as to when he could shoot.

Theres always exceptions, but usually the MG's could be swivel mounted while the cannons turret or fixed mounted. Swivel mounted weapons were almost always employed on bombers.

* Its seems, from watching the TV programs, that the big danger in dogfights was having the enemy get on your tail where you are most vulnerable. Were there any fighter planes in WW11 or other wars which had a co-pilot sitting behind the pilot facing backwards in a plane that had guns facing backwards as well. The co-pilot would have a back window to look of. A plane wouldn't seem to be such a sitting duck if it could fire at an enemy directly behind it.

The Brits had a two man fighter that did have a turret that could shoot backwards. But it failed miserably. When you add a second man, you start adding weight which hurts speed and maneuverability.

The Germans also had their Me-110 that had a man in the back with a MG, but even that type of aircraft was a sitting duck.

[Soren]

Incase you're talking fighters only Harold, the guns don't swivel.

And like Syscom3 said, no good two seat fighter ever appeared during WWII, they were all pretty much sitting ducks for the single seat fighters.

[the lancaster kicks ass]

Generally, a cannon shell is explosive in nature and is larger than a MG bullet. It is considered to be more destructive than a MG, but that is at the expense of a slower rate of fire and a slower muzzle velocity

in the westernw orld i've always believed it that any gun of calibre 15mm or greater is considdered a cannon?

and soren's right, almost all small single seat fighter's had fixed, forward firing guns, you aim the guns by moving the entire plane............

[exec228]

MG 131 and Berezin used HE bullets with 1.4g and 1.8g of explosive and they are still machineguns.
BK 7.5 and Vickers Type "S" used mostly AP shells without explosive and they are still cannons.
classification is subjective and depends on country.
for example, in Germany 44800kg Pz.Kpfw.V Ausf. A (Panther) is classified medium tank, while IS-2 46000kg is heavy in Soviets.

[DerAdlerIstGelandet]

Generally Cannons were explosive and MG not however both types of rounds can be of several different types such as Ball, High Explosive or Armoured Piercing.

[the lancaster kicks ass]

i thought it was done more on calibre like i was saying, 15mm and above being cannon?

[DerAdlerIstGelandet]

I was just talking about the rounds that they fired.

[the lancaster kicks ass]

so am i technically

[exec228]

initial classification of ShVAK is machinegun with 12.7 calibre, especially since it is derived from ShKAS. later the barrel was changed to 20mm.
on the other hand, soviets later developed a tank machinegun KPVT with 14.5mm calibre.
imho it would be logical to consider MG 151/15 as a machinegun, and MG 151/20 as a cannon. interesting that this weapon has an abbrev Maschinengewehrwaffe, not Maschinenkanone as MK 103 or MK 108.
however, opinion of Mauser Werke AG is domiant in this question.

[Harold]

Thanks everyone for the discussion. I am not at the knowledge level where I can draw any final conclusions of this topic. It seems that the manufacturers designation of a gun as an MG or a cannon is what one goes by. There does not seem to be any efforts by anyone to dispute the manufacturer designations.

Being new to this forum, I am hesitant to point out information that other readers may already be very much aware of. But from my earlier research on this topic I found an interesting article at : CANNON OR MACHINE GUN

The article also explains why the Americans made relatively little use of the cannon in WW11. American fighters planes didn't go up against heavily armored bombers, like the Germans did. As for the Japanese, neither their fighters or dive bombers had adequate armor.

Lastly, I'd like to recommend the the History Channel's "Dogfights" program to anyone who is interested in WW11 fighters. The program uses computer animation to show dogfight tactics, and has interviews with the now much older pilots who did the flying.

I reviewed one of the "Dogfight" videos on Guadalcanal last night, having watched it once about a month ago, and was surprised to notice that the Japanese Zero was using 7.7mm MGs and a 20 mm cannon during these battles. A 20 mm MG was also in existence at the time, I understand, but it would be classified as a "heavy" MG. Also, I noticed that the Japanese were using two planes, the VAL and the PETE, which had a rear facing tail gunner. But these planes were dive bombers.

I hope to participate in future discussions on this forum. Harold.

[Tony Williams]

Originally Posted by Harold

But from my earlier research on this topic I found an interesting article at : CANNON OR MACHINE GUN

Yep, that's one of mine.

There wasn't any agreement over the distinction between cannon and machine guns in WW2. This is how I explained it in my book Rapid Fire: the Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces

"This book is concerned with heavy machine guns (HMGs) and automatic cannon. The current usage of these terms has only become generally accepted since the Second World War. Before then, the term "machine gun" was used to describe a relatively small-calibre weapon normally firing solid projectiles while larger weapons were called "automatic guns". The name "cannon" was in English usage an obsolete term for artillery, which by that time were known as guns or howitzers depending on their function. The situation changed in British practice with the selection for the RAF of the French Hispano moteur-canon in the late 1930s. Anglicised as "cannon", the name became adopted for the Hispano and subsequently for all other automatic shell-firing guns of 20mm or more calibre.

Different nations had different practices; in Germany, automatic weapons of up to and including 20mm were known as machine guns (Maschinengewehr) with larger calibres being known as cannon (Maschinenkanonen), leading to the MG and MK prefixes. In addition, designations based on function were used for particular applications, whether or not the weapons were automatic. A gun intended for the anti-aircraft role was called Fliegerabwehrkanone (sometimes given as Flugzeugabwehrkanone or Flugabwehrkanone), for the anti-tank role Panzerabwehrkanone and for mounting in armoured fighting vehicles Kampfwagenkanone; FlaK, PaK and KwK for short. The BK (Bordkanone) designation was used for very large calibre (37+mm) airborne cannon intended for ground attack.

Nomenclature also varied between services. In Sweden, the Air Force called their m/39 12.7mm and 13.2mm guns automatkanon, presumably because they were larger than usual for aircraft guns at the time, while their Navy called the m/32 25mm a kulspruta, (which translates as machine gun), presumably because this was a small weapon by naval standards.

Since the war the definition of a cannon as any fast-firing automatic weapon of 20mm or more has become generally accepted, at least in NATO. The term heavy machine gun has also seen some changes. At one time it was literally used to describe a gun which weighed a lot, of the sturdily-built sort which might be used to defend fortifications, even if it was of rifle calibre. Such weapons have long gone, however, all current rifle calibre machine guns (RCMGs) being relatively light by previous standards, so the term HMG has come to be used for a class of weapon which fits in between RCMGs and cannon. By some form of convergent evolution, the calibre of virtually all HMGs to see service has fallen within the range 12.7-15mm."

Tony Williams: Military gun and ammunition website and discussion forum

[Harold]

Thank you Tony Williams. I regard your explanation as being conclusive.

[syscom3]

Good info Tony.

Harold.... not to confuse you, but at the beginning of WW2, the USN had 1.1 inch MG's as a shipboard AA weapon.

1.1" = 28mm.

As events showed, this was a crappy weapon that was quickly replaced by the popular 20mm Oerlikon.

[Nonskimmer]

Originally Posted by syscom3

Good info Tony.

Yes indeed, it certainly is.
I'd never seen your article "Cannon or Machine Gun" until now either. Excellent.