Alternative airborne guns 2.0

[Shortround6]

I am just saying you can't use Aden MK IV ballistics for an early 1940s gun. Not with a Aden MK IV size cartridges case.
You can get Aden MK IV ballistics early buy using a longer or fatter case or combination. But that affects rate of fire.

The Japanese 30mm type 2 is an interesting point. Scaled up Oerlikon.

• Caliber: 30 mm (1.2 in)
• Ammunition: 30 x 92RB[2]​
• Weight: 51 kg (112 lb)
• Rate of fire: 380 rounds/min
• Muzzle velocity: 710 m/s (2,330 ft/s)
• Shell weight: 273 grams.

I would note that a 220 gram non mine shell in a hypothetical 30mm cannon may not get you the desired results. 22-23 grams of HE?

One reason the MK 108 had such a short barrel is that it pretty much assured the pressure in the barrel had dropped before the breech opened up too much (Bolt hadn't traveled very far). If you are speeding up the bolt speed you are gambling on cartridge case quality. A substandard case can blow out releasing high pressure gas into the action, possible wrecking the gun.

 

[tomo pauk]

I am just saying you can't use Aden MK IV ballistics for an early 1940s gun.

Aden was many things, miracle of ballistics it was not (no need for it, same with DEFA or the post-war Soviet 23 and 37mm guns).
If anything, making a gun that shoots a 220g shell at ~800 m/s should be easier than making a gun that shoots a 440g shell at same MV, yet such guns were made in the early 1940s.

Not with a Aden MK IV size cartridges case.

That is a newly added game rule, isn't it?

I would note that a 220 gram non mine shell in a hypothetical 30mm cannon may not get you the desired results. 22-23 grams of HE?

Japanese (also the French?) were filling their 280g 25mm shells with 15g of HE, or just 10g in the shells that had the tracer element. So unless the shell is thin-walled (but still drilled), the 220 g 30mm shell will probably had well under 20g HE?
(one of the reasons the Japanese were eager to switch to 30mm?)

 

[Shortround6]

Aden was many things, miracle of ballistics it was not (no need for it, same with DEFA or the post-war Soviet 23 and 37mm guns).
If anything, making a gun that shoots a 220g shell at ~800 m/s should be easier than making a gun that shoots a 440g shell at same MV, yet such guns were made in the early 1940s.

It should be easier, if you are willing to make the trade-offs needed. Like a gun double the weight and 1/2 the rate of fire ; (MK 108 vs MK 101)
The trick is getting a light, fast firing gun with good ballistics. Two out of three is not that hard and 1 out of 3 is really easy.
Going to disposable guns helped with weight.

That is a newly added game rule, isn't it?

It may have been added by another poster in post #50
The 30 x 113 Aden may not have showed up until 1958 or after. The 30 x 86 Aden showed up in 1953-54.
Some of the Aden ammo with the 220 gram projectiles holds 50-55 grams of HE but needs a drawn thin wall shell body. The 'normal' 270-275 gram HE shell holds 30 grams of HE.

Japanese (also the French?) were filling their 280g 25mm shells with 15g of HE, or just 10g in the shells that had the tracer element. So unless the shell is thin-walled (but still drilled), the 220 g 30mm shell will probably had well under 20g HE?
(one of the reasons the Japanese were eager to switch to 30mm?)

Madsen gun got 17.5 grams into a 160gram 23mm shell.
Soviets had a little trouble and seemed to have had thicker walls.
Japanese had 10 grams in the shells going into their type 99 guns (either type)

so we have two 20mm guns at 38kg each (or a bit lighter) firing at 490rpm (980rpm total) at 750m/s for 160 grams per second of HE.
The type 2 single 30mm gun 51 grams firing at 400rpm at 710m/s for a total of 193 grams per second of HE (about 20% more)
The single gun is lighter but the firing rate is low and unless you change the feed 42 rounds even in a slow firing gun is not a lot of gun time. About as much time as a Hispano with a 60 round drum.
Please note that the US 37mm aircraft gun only had 45 grams in it's 608 gram shell so the Japanese are not doing to bad. The Germans are just way out in front of everybody else

 

[bf109xxl]

Soviets had a little trouble and seemed to have had thicker walls.

Just curious. Could you please tell a bit more details? Which troubles exactly? 23mm shell for VYa contained 15.6 g HE, for NS-/NR-23 11 g (early variant, shell weight 196 g) and 18 g (late variant - also for the AM-23, shell weight 174g) HE.

 

[z42]

Aden was many things, miracle of ballistics it was not (no need for it, same with DEFA or the post-war Soviet 23 and 37mm guns).

As I mentioned in Large gun Me 109 , the Aden shell is unusually short, which explains why it's so lightweight compared to many other 30mm shells. You could obviously get better ballistics by using a lower diameter but longer shell for the same weight, but perhaps an Aden style shell is good enough considering the short ranges used for aerial gun combat (particularly before radar gunsights and whatnot)? A short stubby shell and a relatively short, neckless cartridge gives other advantages like compactness, maybe easier feeding too? And higher HE ratio?

Japanese (also the French?) were filling their 280g 25mm shells with 15g of HE, or just 10g in the shells that had the tracer element. So unless the shell is thin-walled (but still drilled), the 220 g 30mm shell will probably had well under 20g HE?
(one of the reasons the Japanese were eager to switch to 30mm?)

Wiki mentions the 220g Aden shell has 52.5g HE, or 24%. Which pretty closely matches the mine shell used in the Mk 108, at 85/330g or 26%. Not sure how Aden HE shells are manufactured, are they drawn like the WWII German M-shells?

 

[z42]

It may have been added by another poster in post #50
The 30 x 113 Aden may not have showed up until 1958 or after. The 30 x 86 Aden showed up in 1953-54.
Some of the Aden ammo with the 220 gram projectiles holds 50-55 grams of HE but needs a drawn thin wall shell body. The 'normal' 270-275 gram HE shell holds 30 grams of HE.

To be clear, I wasn't specifying that we must have the exact Aden shell and cartridge. Just saying that IMHO a 220g shell at 800 m/s is quite close to the sweet spot for WWII. Now unless you're Germany and have the capability to manufacture drawn shells, 220g probably means something closer to 25mm rather than 30mm. And maybe we can drop the MV a little bit, 750 m/s should be enough and saves a bit in ammo and gun weight.

 

[z42]

It was done, at least in B-26s and P-51Ds. In the bombers moving heavy ammo from under the gunners feet up to the guns was a problem.

The B-26 and P-51Ds (and other bombers?) used electric servo motors and sprockets to move the linked ammo through the feed ways.

I recall seeing some picture from a bomber tail gunner position where the ammo boxes were located several meters behind the gunner for weight distribution reasons, and there was some electric drive system that helped pull the belts towards the guns.

 

[peceed]

Wiki mentions the 220g Aden shell has 52.5g HE, or 24%. Which pretty closely matches the mine shell used in the Mk 108, at 85/300g or 26%.

It is not just "an ADEN shell", but standardized 30x111 that can be used even by AH-64!
300g would give 28.3%, it is 330g, 25.8% vs. 23.9%.

You could obviously get better ballistics by using a lower diameter but longer shell

It creates disadvantages. Lower caliber decreases the volume of barrel per unit of length (longer barrel or worse propellant utilization), longer shell increases the length of cartridge reducing the rate of fire, and less compact ammunitions takes more space.

 

[tomo pauk]

It should be easier, if you are willing to make the trade-offs needed. Like a gun double the weight and 1/2 the rate of fire ; (MK 108 vs MK 101)
The trick is getting a light, fast firing gun with good ballistics. Two out of three is not that hard and 1 out of 3 is really easy.
Going to disposable guns helped with weight.

You know by now that I don't like 'perfect' stuff, and that I consider every design as a compromise. The better that compromise, the better the design.

Germans - and a few of other people - were fully capable of making an in-between gun. So instead of 100-120g of propellant (MK 101, 103) and 30g (MK 108), there was more than enough of elbow room for a ~100 kg 30mm gun that uses 50-60g of propellant. In a casing that is neither 138mm long, nor a 90mm long one, but something 110-115 mm long, a bit bottlenecked. Yes, the MV is sacrificed, but 650-700 m/s is still good for ww2.
If we want that gun sacrifices the shell weight (as in the case of ADEN 220h shell) by a 1/3rd, the MV will be just splendid for the ww2 aerial warfare.
There is no need to go with disposable guns, especially if the API is the working principle, although for the LW I'd suggest the 'baby 103' or the '151 on steroids' instead of the '108 magnum' so it can function when fit in the wing roots of the Fw 109, as well as a motor cannon on the Bf 109.
(similnar gun would've also made sense for the Soviets)

BTW - the VJa-23 was with better ballistics than the ADEN with 220g shell.

It may have been added by another poster in post #50
The 30 x 113 Aden may not have showed up until 1958 or after. The 30 x 86 Aden showed up in 1953-54.
Some of the Aden ammo with the 220 gram projectiles holds 50-55 grams of HE but needs a drawn thin wall shell body. The 'normal' 270-275 gram HE shell holds 30 grams of HE.

Okay, thanks for clarification.
The 30x86 Aden with 600+ m/s will not have the ballistics of the x113 Aden; perhaps the weaker Aden barely saw any use?

 

[z42]

It is not just "an ADEN shell", but standardized 30x111 that can be used even by AH-64!

Yes, I know, thank you very much. I just used "Aden shell" as a shorthand for "ADEN Mk4+, DEFA 552/3/4, M230, 30x113 etc etc", assuming readers could figure out what I meant.

300g would give 28.3%, it is 330g, 25.8% vs. 23.9%.

That was a typo, thanks for noticing. Fixed the post.

 

[peceed]

will not have the ballistics of the x113 Aden

Just for clarification - it is 30x111.
30x113 is a forward compatible cartridge created by Bushmaster. It uses cases made from light alloys - probably too weak to be used in the non-chain guns.

Germans - and a few of other people - were fully capable of making an in-between gun. So instead of 100-120g of propellant (MK 101, 103) and 30g (MK 108), there was more than enough of elbow room for a ~100 kg 30mm gun that uses 50-60g of propellant. In a casing that is neither 138mm long, nor a 90mm long one, but something 110-115 mm long, a bit bottlenecked. Yes, the MV is sacrificed, but 650-700 m/s is still good for ww2.

There is no point. The bigger gun will have a lower rate of fire, so there is no benefit. The only valid reasons to make (classical) guns heavier are to improve ballistics to get the superior range (mostly irrelevant for fighters) with better penetration or to create "one shot one kill" like in the case of 55 mm.

 

[tomo pauk]

Just for clarification - it is 30x111.
30x113 is a forward compatible cartridge created by Bushmaster. It uses cases made from light alloys - probably too weak to be used in the non-chain guns.

Okay.

There is no point. The bigger gun will have a lower rate of fire, so there is no benefit. The only valid reasons to make (classical) guns heavier are to improve ballistics to get the superior range (mostly irrelevant for fighters) with better penetration or to create "one shot one kill" like in the case of 55 mm.

The 'baby 103' means a gun that is smaller (and lighter) than the normal MK 103, with hopefully better RoF.

 

[z42]

Just for clarification - it is 30x111.
30x113 is a forward compatible cartridge created by Bushmaster.

At least the manufacturer of ADEN cannons calls it 30x113. https://aei-systems.com/wp-content/uploads/2019/08/ADEN-30.pdf

But given it's a neckless cartridge, it probably isn't that sensitive to the exact case length.

 

[ThomasP]

I may be wrong, but I think the 30mm ADEN Mk 1 thru 3 used the 30x111 case, while the ADEN Mk 4 and later variants (and the DEFA) use the 30x113 case.

??

 

[z42]

I may be wrong, but I think the 30mm ADEN Mk 1 thru 3 used the 30x111 case, while the ADEN Mk 4 and later variants (and the DEFA) use the 30x113 case.

??

No, the ADEN Mk 1-3 used a 30x86 cartridge. See picture I posted at Large gun Me 109

I'm not sure it saw much service, as it was replaced after just a few years by the common British/French 30x113 (or 30x111, as it may?) used in the subsequent ADEN Mk 4+ and DEFA 550 series cannons, and later in other applications as well.

 

[Shortround6]

I'm not sure it saw much service, as it was replaced after just a few years

True but in may have equipped ALL of the RAF Hawker Hunters as originally built. It may well have equipped most of the British fighters of the 1950s that had 30mm guns.

 

[z42]

Germans - and a few of other people - were fully capable of making an in-between gun. So instead of 100-120g of propellant (MK 101, 103) and 30g (MK 108), there was more than enough of elbow room for a ~100 kg 30mm gun that uses 50-60g of propellant. In a casing that is neither 138mm long, nor a 90mm long one, but something 110-115 mm long, a bit bottlenecked. Yes, the MV is sacrificed, but 650-700 m/s is still good for ww2.
If we want that gun sacrifices the shell weight (as in the case of ADEN 220h shell) by a 1/3rd, the MV will be just splendid for the ww2 aerial warfare.
There is no need to go with disposable guns, especially if the API is the working principle, although for the LW I'd suggest the 'baby 103' or the '151 on steroids' instead of the '108 magnum' so it can function when fit in the wing roots of the Fw 109, as well as a motor cannon on the Bf 109.

A 30mm gun able to fit as a motor cannon as well as wing mounted and a MV of, say, 700 m/s, probably needs to sacrifice some weight compared to the 330g M-shell they historically used. I think that would have been an acceptable tradeoff, in order to reach higher MV than the Mk 108. Ignoring propellant (because I'm too lazy to look up data and take that into account), the same shell momentum as the Mk 108 is reached with a 255g shell at 700 m/s. So maybe something in that ballpark?

 

[tomo pauk]

A 30mm gun able to fit as a motor cannon as well as wing mounted and a MV of, say, 700 m/s, probably needs to sacrifice some weight compared to the 330g M-shell they historically used. I think that would have been an acceptable tradeoff, in order to reach higher MV than the Mk 108. Ignoring propellant (because I'm too lazy to look up data and take that into account), the same shell momentum as the Mk 108 is reached with a 255g shell at 700 m/s. So maybe something in that ballpark?

A gun of about 100 kg weight that uses ammo with propellant weight of 50-60 kg already sacrificed the MV vs. the MK 103 that was ~140 kg heavy and used ammo with propellant weight of ~110g for the M-shell (the MK 103 used just 30g).
The MK 108 with a much lighter shell, somewhat longer barrel and a bit hotter loading woul've certainly be able to go above 600 m/s, and perhaps to 700 m/s. Quirk with using a much lighter shell is that the desired target effect that the 330g heavy M-shell provided before is no longer there - now perhaps 7-8 shells is required to down a 4-mot vs. just 5 for the 'normal' MK 108? Granted, a far better equation than with the 20mm guns with 20 shells required.

On the other hand - why not having both? Bf 109 has the 100 kg gun in the Vee, and two 60 kg guns preferably in the wing (no cowl MGs so at least some weight and drag increse is cancelled), while the Fw 190 has two 60 kg guns out of the prop arc and two 100 kg guns in the wing roots (also no cowl guns).
Three 100 kg guns on the Me 262. Two 60 kg guns on a 1-engined jet fighter (advantage of the lighter but faster shell is that it will make lower recoil than a heavy but slow shell).
Use the MK 108 with the shell close to the historical one on the night fighters.
Mate the lighter shell on the 100 kg ammo for a Flak usage.

 

[z42]

Quirk with using a much lighter shell is that the desired target effect that the 330g heavy M-shell provided before is no longer there - now perhaps 7-8 shells is required to down a 4-mot vs. just 5 for the 'normal' MK 108?

Yes, obviously. But as I mentioned, a sacrifice worth taking IMHO. Also with higher velocity and flatter trajectory it would be easier to hit the target in the first place, somewhat compensating for the lesser effect per hit.

On the other hand - why not having both?

I'm a fan of the logistical and shooting advantages of a uniform armament.

Bf 109 has the 100 kg gun in the Vee, and two 60 kg guns preferably in the wing (no cowl MGs so at least some weight and drag increse is cancelled), while the Fw 190 has two 60 kg guns out of the prop arc and two 100 kg guns in the wing roots (also no cowl guns).

That's, er, an awful lot of gun for a single engine fighter to carry. But hmm, if you can make your 100kg gun be reliable enough and have a decent RoF, maybe the 109 can be equipped with one of those in a motor cannon installation as the sole gun. That would work weight-wise. And two of those in the wing roots for the 190, again no other guns?

 

[tomo pauk]

Yes, obviously. But as I mentioned, a sacrifice worth taking IMHO. Also with higher velocity and flatter trajectory it would be easier to hit the target in the first place, somewhat compensating for the lesser effect per hit.

Agreed pretty much.
It would've also been a much better anti-fighter weapon than the MK 108 with the historical shell.

I'm a fan of the logistical and shooting advantages of a uniform armament.

The shooting of two different wepons that have the similar MV will still be there.
I have nothing against the logistical advantages of an uniform armament, but perhaps the ease of installation should take precedence? Ie. whatever is a good motor-cannon is perhaps not the best weapon to install in the wing outside the prop arc.

That's, er, an awful lot of gun for a single engine fighter to carry. But hmm, if you can make your 100kg gun be reliable enough and have a decent RoF, maybe the 109 can be equipped with one of those in a motor cannon installation as the sole gun. That would work weight-wise. And two of those in the wing roots for the 190, again no other guns?

Yes, quite the batteries I've suggested, even if we take in the account what the LW was trying to do (like two MK 103s under the 190's wings, or the three MK 108s + two MG 131s on the 109).
Granted, two 100 kg guns in the wing root of the Fw 190 are a very high firepower for the day. Adding two MK 108s in the wing is perhaps over-the-top.
As a less heavy alternative, both Fw 190 and the Bf 109 can take a belt-fed MG FFM in the outer wings (easier to do for the 109 than trying to install the MG 151s within the wings) - at just under 700 m/s with the M-shell, it still adds to the total firepower while being much lighter than the MK 108 set-sup. And less draggy, FWIW.