Luftwaffe Cannons and Machineguns topic.

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It's kind of interesting to see that in the post-WWII era aircraft guns have largely converged to 25-30mm caliber ones, the USA being somewhat of an outlier with the 20mm Vulcan but that has been replaced by a 25mm gatling gun in the F-35. Of course jets are powerful enough that they can afford to carry a high-velocity gun (typically muzzle velocity is around 1000 m/s) with a high rate of fire (gatling or revolver cannon type), but they haven't gone up from 30mm either.

In the WWII era it seems a 30mm high velocity gun entailed too much compromise (see how massive the Mk103 is, and relatively low RoF). But maybe a high velocity 25mm gun could have been feasible for mounting in a typical WWII fighter?

As for the mechanism, yeah it seems the API blowback used by the MG/FF and Mk108 was somewhat of a dead end, and not really suitable for higher velocity guns. One sort of hybrid mechanism that supposedly achieves fairly high RoF and is usable for higher velocity guns as well is "gas-unlocked blowback", where instead of the mass of the bolt preventing the backwards movement in the initial stages after firing, the bolt is locked and there is a gas mechanism that unlocks the bolt and then the rest of the action happens by blowback.
 
The German's MG213 and MK213 was highly innovative, and were 20mm and 30mm respectively.

There is a certain point where the caliber of the weapon along with it's weight, has to be worth the effort to be used in an aircraft's armament.

With the exception of the GAU-8, which had an airframe built around it, most cannon have to be able to work within the aircraft's performance profile.
 
z42 said:
In the WWII era it seems a 30mm high velocity gun entailed too much compromise (see how massive the Mk103 is, and relatively low RoF). But maybe a high velocity 25mm gun could have been feasible for mounting in a typical WWII fighter?
Click to expand...
25mm guns were probably missed opportunities for Germany, japan and Soviet Union.
Soviets have gotten close with the VJa-23 (although it's usage on fighters was meager).


API blowback was also used on the high-velocity Oerlikon S gun.
API allowed for the cartridge to be fired before it is chambered, that in combination with mass of the bolt and it's supporting members, as well as the strength of the return spring was sufficient to keep everything safe. A way to improve the RoF on the API blowback guns was to lighten the recoiling members + stiffer main spring + installation of recoil buffers; Swiss (for the Oerlikon S that became the SS2 now) and Japanese (Type 99 Mod 5) did that by the end of the war.
See here.
Germans were increasing the RoF on the MK 108 from 600 to 850 rd/min when the war was ending.
 
The MG213 must rank as the premier air to air gun, for longevity, performance and widespread application.

Eng
 


And 40 rounds seems just for outer wing cannons. The wing root guns can pack more.

Why is the wing root installed MK 108 weaponry weight so much less than for the MG 151/20 in the same location (112 to 137 kg).
Because a single MK 108 weighs 58 kg and an MG 151/20 ca. 42 kg.
 
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'Advanced primer ignition' weapons have a soft recoil, so perhaps the mounting can be made of weaker and thinner material, and thus be lighter?

Wing root MK 108 will not work anyway, since these are the API system weapons (same as the Oerlikon S, L or FF, ias well as the Ikaria MG FF) - ignition times of API are too unpredictable for a synchronized weapon.
 
Former member HoHun argumented in detail on a German forum that the low MV of the MK 108 was not that much a problem as perceived for most air combat distances where direct shooting is involved.
Like the shallower drop of high velocity guns is offset by their greater dispersion.

Not sure if he also engaged in this topic in English somewhere.

I'm amazed the MK 108 offers even A LOT more bang per weight installed as thought than the MG 151/20.
 
The problem is not trajectory, very often over emphasized by authors and internet "experts". Just tilt the guns up a bit to keep them on target at the closer ranges.
What that does not do is solve the time of flight problem. At sea level in thick air the MK 108 Ausf A ammo took 0.696 seconds to reach 300 meters. The 13mm MG 131 ammo took .49 seconds. A 300mph (484kph) airplane moves 13.4 meters per 1/10 of a second.
The MG 151/20 117g HET round needs 0.477 to cover 300 meters.
Things get a lot worse at longer ranges and better at shorter ranges. The 30mm round lost 26% of it's velocity in the first 300 meters.
Now at 20,000ft (6000 meters) in thinner air the velocity loss is not so bad.
Against slow bombers things are not so bad, against fighters? Needing to aim 4-8 plane lengths ahead makes things rather difficult. If you can get close you need less lead.

High velocity guns work a lot better at defection shooting. Which is why most of the bomber attacks were from behind or from the front. Simplified the lead problem.

But the 30mm does have a limited range problem. It is more limited firing envelope (range estimation) than actual range.
 
The D-9 packed 250 rounds per MG 151/20. How much would the Anton versions pack? As much?

And are there stats for the MG 17 weight (gun, mount, ammo) installed in the A-6?
 
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