Favorite gun armament of WWII aircraft

[Fokker D21]

He HoHun

I just read your website HoHun's Air Warrior 3 Site (Main Page)

I noticed that you have some missing data. Even if you don't entirely agree with my formula (or agree at all), my website still gives a lot of technical data about projectile weight (not cartidge weight), muzzle velocity, rate of fire, ammunition make up, gun weight, types of guns used per fighter and ammunition supply.

I also noticed that according to both your and my calculations the MK 108 is the most efficient weapon used during world war two.

 

[HoHun]

Hi Fokker,

>I just read your website HoHun's Air Warrior 3 Site (Main Page)

Oh, that's ancient stuff I only keep online for reasons of nostalgia Note that I have calculated only the mass output there, which seriously underestimates explosive (and incendiary) rounds.

Here is a more recent table listing total firepower for a number of batteries of roughly equivalent firepower and accurately equivalent ammunition supply.

 1x MK 108           -  87 rpg - 111 kg - 221% firepower - firepower per weight: 900%
 1x MK 103           -  75 rpg - 210 kg - 180% firepower - firepower per weight: 387%
 2x MG 151/20 (MX)   - 187 rpg - 164 kg - 124% firepower - firepower per weight: 342%
 2x MG 151/20        - 207 rpg - 172 kg - 112% firepower - firepower per weight: 294%
 2x Hispano V        - 212 rpg - 188 kg - 109% firepower - firepower per weight: 262%
 2x Hispano II       - 206 rpg - 201 kg -  94% firepower - firepower per weight: 211%
 3x MG-FF            - 149 rpg - 235 kg - 103% firepower - firepower per weight: 198%
 5x MG 151           - 239 rpg - 428 kg -  97% firepower - firepower per weight: 102%
10x MG 131           - 311 rpg - 413 kg -  93% firepower - firepower per weight: 102%
 8x .50 Browning M2  - 250 rpg - 452 kg - 100% firepower - firepower per weight: 100%
25x Browning .303    - 399 rpg - 549 kg -  96% firepower - firepower per weight:  79%
25x MG 17            - 406 rpg - 596 kg -  95% firepower - firepower per weight:  72%

I think that's pretty close to your type of evaluation, except that I don't assign arbitrary factors based on projectile type, but only add up the total kinetic and chemical energy.

>projectile weight (not cartidge weight)

Cartridge and belting/magazine weight appears to be the most difficult parameter to find.

Here is a list of the guns that are already in my list, but can't be added to the above comparison because I haven't found data on the cartridge/belting weight:

MK 213/30
VYa-23
NS-37
20mm Type 99-1
20mm Type 99-2
Ho-1 / Ho-2
12,7mm UB
Berezin B-20
37mm M4
20mm Ho-5
20mm ShVAK
12,7mm Scotti
Breda-SAFAT
Ho-103

Even if you could point out the data for just one of these, that would already help me

>I also noticed that according to both your and my calculations the MK 108 is the most efficient weapon used during world war two.

Absolutely, and the advantage actually increases if you don't look at mass output but at total power output. Of course, this advantage is paid for with a low muzzle velocity, but Luftwaffe trials showed that the high rate of fire and the low dispersion of the weapon made it more effective against bomber targets than the MK103.

I don't like the somewhat vague term "effective range", but if you consider "point blank range" the maximum distance at which you can put the crosshairs directly on the target without accounting for drop and still have the centre of the pattern on a fighter-sized target, the MK108 as sighted in the Me 109 comes out with a point-blank range of 500 m.

For comparison, the P-38 with its 12.7 mm Browning has a point-blank range of 700 to 800 m.

(Of course, this range is relevant only against a non-manoeuvering fighter, but it's meant as an improvement on the "effective range" term which doesn't specify the target behaviour either.)

Regards,

Henning (HoHun)

 

[Fokker D21]

HoHun, I'm slightly confused about your requested data.


The website WORLD WAR 2 FIGHTER GUN EFFECTIVENESS mentions energy calculations that are made by you?

The same website also gives the round weight (= cartridge weight) for several rounds. As a matter of fact, the only one missing is the 30x85B cartridge for the MK 213 (= MG 213C).

This round will problaby weigh slightly less than the 30x90RB round for the MK108 (at 480 grams). It has the same 330 grams projectile weight.

As far as the effective range is considered, I agree with you. In World War two however, fighters would mostly engage at ranges below 300 meters. The MK 108 against bombers was often fired at ranges even below 50 meters and sometimes even below 10 meters. That gives a whole other meaning to being on top of the target. You can practically stick your arms out of the cockpit and touch what you are shooting at.

 

[HoHun]

Hi Fokker,

>The same website also gives the round weight (= cartridge weight) for several rounds.

Roger, but the figures on Tony's site unfortunately don't listithe total weight including belting which determines the actual weight of the weapons system.

The difference to the "naked" cartridge usually is large enough to care about it.

>You can practically stick your arms out of the cockpit and touch what you are shooting at.

Remember to keep your arm movement synchronised with the propeller, though

Regards,

Henning (HoHun)

 

[Tony Williams]

Some other articles on my website relevant to this discussion are:

CANNON OR MACHINE GUN

IDEAL WW2 FIGHTER ARMAMENT

and

ANOTHER MISSED OPPORTUNITY: THE OERLIKON FFL CANNON

 

[krieghund]

There's nothing like jumping in a Spit MkI and defending Pearl on dec 7th. When you hit the IJN aircraft its like a 12 gauge in full bore on the skeet range...nothing but dust.

I use it in MS CFS II but don't dogfight the zeros.


Loose the dogs!!!

 

[HoHun]

Hi Fokker,

>In World War two however, fighters would mostly engage at ranges below 300 meters.

Quoting "No Guts, No Glory":

"Contrary to much that has been published, the Fighter Pilots [in Korea] who shot down an occassional Mig or two, got them around 122-366 meters just like they did in Europe and the Southwest Pacific during World War II."

In fact, it's interesting to note that while the permissible deflection increases (approximately) linearly with muzzle velocity, the target "area" (actually, the two-dimensional angle) decreases with the square of the range.

That's one reason the "search for high velocity" did not result in an operational high-velocity aircraft gun - firing range was not as important as destructiveness in actual combat. After all, it was relatively easy to get closer to a target in air combat (unless, as "No Guts, No Glory" points out, one's aircraft was seriously outperformed and one had to take "desparation shots").

The other reason high velocity was of limited value was that high-velocity guns suffered from barrel vibrations that increased the size of the pattern considerably. Instead of hitting the aim point accurately, high-velocity guns would shower the general area of the target with projectiles, which made it difficult to achieve the concentration of fire necessary to actually knock down the target.

Thus the 122 - 366 meter figure m provided by "Boots" Blesse.

Regards,

Henning (HoHun)

 

[Fokker D21]

Mr Williams, I think your book "Flying Guns of WW2" is clarifying and well written. I love to read books wich are written based on decent historical research.

Especially stories that contradict populair belief have my intrest. For instance the USA failing in every attempt to get a 20 mm gun in service. Or the Soviets having the most efficient guns but not being able to take full advantage of them because of the limited guns per fighter. And there are many others.

I took the challenge to come up with a gun power formula of my own (see my website) based on kinetic and chemical damage. I also took the liberty to redo your calculations a little bit more accurate and fore more guns. Please let me know what you think of it.

One thing is interesting tough. The end result is very close to your formula.
To make the cartridge power figures more accurate, I multiplied your cartridge power values with the factor 3, otherwise all rifle calibre machine guns would get the figure 1.

 

[Fokker D21]

I have a question. Does anyone know how many rounds the wing root MG 17's in the Focke Wulf Fw 190 A1 had. No German manual or document I found gives any information about this. Furthermore there is some contradicting info on the amount of ammo for the engine mounted MG 17's which is sometimes 850 and othertimes 900 rounds per gun. And last but not least is it the A5 version that switched the 60 rounds drums for the outboard MG FF/M's for 90 rounds?

 

[Tony Williams]

Mr Williams, I think your book "Flying Guns of WW2" is clarifying and well written. I love to read books wich are written based on decent historical research.

Especially stories that contradict populair belief have my intrest. For instance the USA failing in every attempt to get a 20 mm gun in service. Or the Soviets having the most efficient guns but not being able to take full advantage of them because of the limited guns per fighter. And there are many others.

I took the challenge to come up with a gun power formula of my own (see my website) based on kinetic and chemical damage. I also took the liberty to redo your calculations a little bit more accurate and fore more guns. Please let me know what you think of it.

One thing is interesting tough. The end result is very close to your formula.
To make the cartridge power figures more accurate, I multiplied your cartridge power values with the factor 3, otherwise all rifle calibre machine guns would get the figure 1.

I'm pleased you enjoyed the book (if anyone's interested, it has sold out but the publishers are printing another 500 this month - with a few minor amendments, I hope).

It's always possible to amend the factors in any firepower formula (Henning made some suggestions which are included at the end of the article on my website). However, the variables involved are so huge in terms of exactly where the bullet or shell hits and the path it takes, that there is a limit to the degree of precision which it is worth having. And as you point out, at the end of the day the gun comparison results turn out to be much the same.

 

[Denniss]

The A-5/A-6 manual lists 900 rounds 7.92 mm as maximum for the engine MG 17.

 

[KrazyKraut]

Sorry to revive this thread but I have to voice my opinion

When I think perfect armament I somehow always end up at the longnosed 190s:

D-9: Perfect multi-role armament with a bias towards anti-fighter work. 2 20mm and 2 13mm placed reasonably close together and close to the ReVi-sight. Not as unforgiving as the 109s all-centered armament, though. No wing mounted cannons that jam, no flexing, no adverse effect on roll-rates.

Another option that'd be interesting is to replace the 13mm MGs with a third MG151 firing through the spinner: That would reduce drag a bit (no bumps on the cowling) and make aiming more predictable as all guns would have roughly the same trajectory. Also you can't argue with a good engine cannon (assuming you can make one that is reliable), at least in theory it seems like the best place for a gun overall. I think they tried that armament on one of the Doras too.

D-13(???): Good allround armament, this time biased towards intercepting bombers: The centerline 30mm inflicts serious damage and the two 20mm do their part and provide more than self-defense against fighters.