Alternative airborne guns

[tomo pauk]

This might not be much of an advantage.
For a give stage of fuse development you can't make the fuse lighter so that means you cut the body of shell and the HE capacity more than the 75-76% indicated.
The 30mm mine shell already lost velocity at a pretty alarming rate. A shorter, stumpier projectile will loose velocity even faster so you may not get much, if any, increase in practical range. That is much difference in time of flight to a given/desired range.

330g shell was supposed to loose 130 m/s from a still-standing muzzle to 300 m, as well as having the drop of 2.17m - both at sea level. Let's say, for sake of discussion, that 250 g shell looses the speed at 20% greater rate. That is about 155 m/s loss from muzzle to 300 m. Even if the MV is 600 m/s, that is still a faster shell to cover 300m, with benefits for any aspect of ballistics, thus increasing the hit probability.
Low density air at ETO altitudes where a hard-hitting cannon will lessen the rate of velocity loss.

 

[JuniorJarhead09]

Idea is that we 'design' better guns for different airforces for 1937-1945. Guns for different purposes - fixed installations for fighters (predominantly for air-to-air combat), guns for defensive fire, anti-tank guns etc. Slight modification(s) of guns 'borrowed' from countries', whether freindly or not, also count. Alternative suggestions - 'plan B's - are also okay. Ideally, suggestions should've been based on operating principles known and feasible in the era. Ditto for improved ammo.

(we can do better than just suggesting the .50 BMG for Spitfires and Hurricanes of 1939-40)

My question is I was told by flying guns of ww2 and rapid fire. They plenty of options and if Rheinmetal had designed a proper 25mm. they could've made it quite devastating.

I'm thinking and MG131s are pushed earlier.

Everyone always says mg213….. issue with 109 cowling doesn't allow 3…. And Poor Old Willy didn't think to incorporate space with landing gear. He had plenty of chances to. When he went from the E to the F and to the G or the K. He was okay with the gondolas.

 

[Shortround6]

Lots of questions.

My question is I was told by flying guns of ww2 and rapid fire. They plenty of options and if Rheinmetal had designed a proper 25mm. they could've made it quite devastating.

What is a proper 25MM?
The problem with larger guns is that the size of the gun and ammo go up with the cube of caliber, IF everything else is equal.
Basically a 25mm gun is going to be about double the weight of 20mm gun and the ammo is going to be about double the weight.
20mm guns caried from about 24 kg (Japanese type 99-1) to about 50+kg for the Hispano. Sort out shell weight, desired velocity and rate of fire.

I'm thinking and MG131s are pushed earlier.

It took 4-6 years depending on start of project. Not helped by developing two different ignition systems/primers. Conventional primers/firing pins for non synchronized mounts and electric primers and electric contacts on the face of the bolt for synchronized guns. Perhaps the conventional guns could be/were developed first. Might have been synchronized at slower rate of fire?
Problem for the Germans when using flexible guns is one MG 131 worth more or less than MG 81 or MG 81Z?

Everyone always says mg213

Everyone wants to ignore all of the problems of turning an "idea" into a working gun.
Americans, British, French and Russians took years, with the help of some of the German enginers and in the face of the atomic bomb threat to get revolver cannon to work.

ssue with 109 cowling doesn't allow 3…. And Poor Old Willy didn't think to incorporate space with landing gear. He had plenty of chances to. When he went from the E to the F and to the G or the K

I have no idea why Willy and the boys took the guns out of the wings of 109. They had an MG 17 in many of the 109 C & Ds and they had an MG 17 or 20mm MG/FF in the 109Es.
Putting a MG 131 in each wing should have been easy. Improvement in fire power over a 20mm is the problem. While the MG 131 is about twice as powerful as the MG17 it is about 1/4 as powerful as the MG 151/20. Assuming you can get the MG 151 to fit in the wing. (Japanese and Italians could not or had a lot of trouble). Using 3 different guns with 3 different times of flight is hardly a good solution even if it was done.

 

[JuniorJarhead09]

Lots of questions.

What is a proper 25MM?
The problem with larger guns is that the size of the gun and ammo go up with the cube of caliber, IF everything else is equal.
Basically a 25mm gun is going to be about double the weight of 20mm gun and the ammo is going to be about double the weight.
20mm guns caried from about 24 kg (Japanese type 99-1) to about 50+kg for the Hispano. Sort out shell weight, desired velocity and rate of fire.

It took 4-6 years depending on start of project. Not helped by developing two different ignition systems/primers. Conventional primers/firing pins for non synchronized mounts and electric primers and electric contacts on the face of the bolt for synchronized guns. Perhaps the conventional guns could be/were developed first. Might have been synchronized at slower rate of fire?
Problem for the Germans when using flexible guns is one MG 131 worth more or less than MG 81 or MG 81Z?

Everyone wants to ignore all of the problems of turning an "idea" into a working gun.
Americans, British, French and Russians took years, with the help of some of the German enginers and in the face of the atomic bomb threat to get revolver cannon to work.

I have no idea why Willy and the boys took the guns out of the wings of 109. They had an MG 17 in many of the 109 C & Ds and they had an MG 17 or 20mm MG/FF in the 109Es.
Putting a MG 131 in each wing should have been easy. Improvement in fire power over a 20mm is the problem. While the MG 131 is about twice as powerful as the MG17 it is about 1/4 as powerful as the MG 151/20. Assuming you can get the MG 151 to fit in the wing. (Japanese and Italians could not or had a lot of trouble). Using 3 different guns with 3 different times of flight is hardly a good solution even if it was done.

Please patient as I am not as smart or educated as you and my brain can't slow down: This is why I was a fan of 3- 20 mm grouped together in the nose and wing wing roots like the G-56 you can compensate…..
RM used I believe 25/26 mm cartridge with mk103 I haven't found the testing for ballistics.

Remember aerial combat is so quick and I-d rather shoot 3 20s with a tight spread vs a single 30mm that acts like a shot gun…. Japans 30mm type 5 cannon I think was a decent option if shared and developed.


I understandable the the whole 30mm but mg151/23 was already pushing the limits of the MG151…. 23mm I believe was for the APHE filler….. due to minengeschob.



This is why I was saying a 25mm vs a 30'm…

I'm more for smaller, simpler and feasibility.

3- mg151/20s…. Not really gonna be concerned about doing another pass.

Or go with 3-25mm in the nose of all-metal Pyörremyrsky (I've been working on a short novel; using period accurate information)

But the APHE in the mg151/23….. they wanted to increase the filler…. Standard 151/20 had 4 g…. MG151/23 was treated as a barrel/chamber modification


If average is 25 hits to take down b-17…


Also MK108 was developed in 1940….. you can't increase ballistics in that time period?
MK-103 entered 1943.


My brain: if you have 2 plot points already. Work your way to the best of middle ground. More ergonomic and less bs. 28 hands in a pack of 12 eggs doesn't work.


Some- 190A-6 did get mg151/23

Which is 23x115 vs standard 20 x 82 ……
made longer & necked up doubling the HE.

Side note MG131s had IAI and those were more effective than people think. They behaved like "mini-mineshell" round. Some pilots hated them and some loved them.

Having one gun simplifies training/logistics/shooting/predictability. 3-20mm is all about grouping…. Yeah I hit you but it's 3 at the same time….. it fires its rounds are fast enough for the following round to to in the same hole in some situations… I'm not hitting you with 18 grams now. It's 54 grams. That's a lot for a plane to take.

 

[MIflyer]

Now, if the firing rate was high enough.....

 

[JuniorJarhead09]

Now, if the firing rate was high enough.....

View attachment 887848

 

[Dimlee]

Now, if the firing rate was high enough.....

View attachment 887848

...to destroy the airframe...

 

[GTX]

Design study for F-16 with 20mm Vulcan cannon replaced with 30mm cannon:

 

[muskeg13]

...to destroy the airframe...

Speaking of cannon toting WW2 aircraft larger than 30mm:
Why? What targets are you hoping to effectively engage with a cannon? What is your definition of a successful engagement, and what structural damage and increased maintenance are you willing to accept?

I don't believe any of the really large caliber (40-102mm) cannon equipped WW2 aircraft proved effective, and these "good ideas" were eventually dropped. Rate of fire, ability to load and target with any repetitive accuracy, the effects on target when they got an occasional lucky hit, and self-inflicted structural damage led to the demise of aerial heavy cannon use. The ability to engage with cannons for one or two missions before having to write off or rebuild your aircraft isn't very cost effective.

Using the B-25 as an example, this great idea was only employed for a relatively short time before all of the cannon equipped aircraft were reconfigured to .50 Cal gunships. Why? Firing the 75mm cannon popped rivets and fractured structural members that required major repairs. The rate of fire was far too slow. The straight level run in to align the sight and fire made the aircraft more vulnerable to AA fire. The gun and ammo was heavy and ate into the capacity to carry more bombs that were more destructive on targets. Accuracy wasn't that good, and even when they hit, the cannon shells didn't prove that effective on any shipping larger than barges. Trying to hit small ground targets, like bunkers, was almost impossible under combat conditions, particularly when there was incoming ground fire. If the Japanese had many tanks to deal with, I'd think trying to take out a fast moving tank would be even worse.

No, bombs, rockets, .50 Cal and 20mm got the job done.

 

[GrauGeist]

The 75mm cannon armed B-25 used it primarily to destroy shipping in the PTO.

 

[Shortround6]

The 75mm cannon armed B-25 used it primarily to destroy shipping in the PTO.

True but 75mm gun installations were planned for the A-26, the P-38 and the P-58 and perhaps others.
What the intended uses were seems to have varied.

 

[GrauGeist]

True but 75mm gun installations were planned for the A-26, the P-38 and the P-58 and perhaps others.
What the intended uses were seems to have varied.

The trials on the B-18 led to the successful installation on the B-25. The structural damage to the B-18's frame was analyzed and the results used to create a better function to the B-25's airframe.
In regards to the P-58, it was never intended to have the 75mm cannon...perhaps you're thinking of Beech's A-38 "Grizzly"?

 

[muskeg13]

The trials on the B-18 led to the successful installation on the B-25. The structural damage to the B-18's frame was analyzed and the results used to create a better function to the B-25's airframe.
In regards to the P-58, it was never intended to have the 75mm cannon...perhaps you're thinking of Beech's A-38 "Grizzly"?

and it didn't effectively work in operation . Ever!

 

[GrauGeist]

and it didn't effectively work in operation . Ever!

Sorry, but I have to call this "opinion" as total bullsh!t.

Plenty of instances where the cannon armed B-25s raped Japanese shipping.

It's been discussed on this forum in several places and even a Google search will provide ample evidence.

 

[tomo pauk]

RM used I believe 25/26 mm cartridge with mk103 I haven't found the testing for ballistics.

I understandable the the whole 30mm but mg151/23 was already pushing the limits of the MG151…. 23mm I believe was for the APHE filler….. due to minengeschob.

These claims will need a motherlode of primary sources to be believed.

If average is 25 hits to take down b-17…


Also MK108 was developed in 1940…..

So will these.

Some- 190A-6 did get mg151/23

Which is 23x115 vs standard 20 x 82 ……
made longer & necked up doubling the HE.

Side note MG131s had IAI and those were more effective than people think. They behaved like "mini-mineshell" round. Some pilots hated them and some loved them.

Ditto.

 

[muskeg13]

Sorry, but I have to call this "opinion" as total bullsh!t.

Plenty of instances where the cannon armed B-25s raped Japanese shipping.

It's been discussed on this forum in several places and even a Google search will provide ample evidence.

Oh yeah, I guess that's why the 5th AF kept their cannon armed B-25s until the end of the war and didn't replace all of their 75mm Cannons with additional .50s. Google provides no solid evidence to prove the 75mm cannon was an effective shipping weapon except for one account of a cannon armed B-25 sinking a small destroyer and a few clips of hits against unescorted unarmed very small freighters.
They were useful in hunting barges, but .50 Cal gunships were better. There are multiple accounts of .50 Caliber aircraft managing to sink ships, including at least one account each by an F4F and a P-51, but the .50 isn't really seen as a ship killer. These lucky shots led to fatal fires caused by igniting exposed fuel and munitions. 5th AF B-25s were highly effective against Japanese shipping, but not by using the 75mm Cannon. They excelled at executing coordinated attacks using B-25 gunships for suppression of AA and sinking ships with 500 and 1000 lb bombs in mast height or skip bombing attacks. Later in the war, Japanese shipping was engaged with rockets, not cannon larger than 20mm.

 

[yulzari]

The twin 40mm S-Guns with HE on Hawker Hurricanes proved very accurate and effective in Burma. The 57mm automatic 6 Pounder gun on the De Havilland Mosquito also proved effective in its anti submarine rôle (and air to air on. Ju88).

In both cases they were superseded by x8 rockets (60 lb HE or 25 lb solid) which allowed the airframe to be more versatile in employment and eliminated the post firing weight of the guns. The Mosquito also was stress estimated and ground trialled with a 94mm 32 Pounder gun and the Australians trialled á Beaufighter with a 40mm Bofors Gun. In 1941 á Beaufighter in the UK was built with twin 40mm S Guns.

 

[Shortround6]

A few notes

Also MK108 was developed in 1940….. you can't increase ballistics in that time period?
MK-103 entered 1943.

Be very careful when stating "dates" for program start, development and entry into service.
Gun programs often took 3-6 years to go from "start" to service weapons in squadron service.
MK-101 was the first 'service' German 30mm but it was very heavy and slow firing so they didn't make many and they were looking for something better but not working very hard.
MK-103 used the same ammo as the MK-101 so that was a head start, They wanted a lighter, faster firing gun. They got it but it was still too heavy and didn't fire fast enough.

Which is 23x115 vs standard 20 x 82 ……
made longer & necked up doubling the HE.

Soviet 23X115 didn't show up until the end of war. It won't fit in a MG 151/20 gun but you could make a larger gun based on the MG 151 design. Gun will be larger and heavier. This assumes you build to German (or American/British) standards. Russians built very light weight guns but they accepted that such guns would wear out very quickly.
Germans may have played around with 22mm and 23mm calibers but didn't get very far.

Side note MG131s had IAI and those were more effective than people think. They behaved like "mini-mineshell" round. Some pilots hated them and some loved them.

The MG 131 could be more effective that some people think. But we have some confusion as to what is a "mini-mineshell" round.
They used a pretty much standard, although small, HE round. Due to scaling the HE content was small.
German "mineshells" used a different form of construction with the shell bodies drawn instead of bored out of solid bar stock. Due to the thinner walls they had much more space for HE. Germans never introduced into service such a drawn HE shell for the MG 131. Allies never used a "mineshell) until the 1950s?
German 13mm MG round held around 1.2 grams of HE compared to the American .50 cal (no HE) and the roughly 10 grams for most 20mm shells.
Now we run into a number of problems with shell design and use.
A normal HE shell holds more HE than an HE-T shell as you need space for the tracer and you have to separate the tracer section from the HE to keep it from exploding before you want it to.
An AP round often has no HE.
Using very small quantities of incendiary material sounded cool but it often didn't work. Germans tried putting 0.3 grams of incendiary into one version of the 13mm HE ammo.
Americans were using 2 grams in the M 8 .50 AP round. Americans were using pretty much only the M8 round from late 1943 on. German were using mixed belts of HET, incendiary and AP. A lot of success or failure was depending on which bullets hit where on the target aircraft.
MG131 had about the same time of flight as the German 7.9mm guns. It was more effective when it got there but it didn't have any extra range. The American .50 had a short time of flight and had a longer combat range. It also started with a lot more kinetic energy.
A lot of HE rounds had trouble penetrating inside the aircraft and exploded on the skin. This could be solved with time (better fuses) and cost.
What works on a fighter often does not work on a bomber.
Sometimes pilots could see the impact of small HE rounds and knew they were hitting and this was useful even if the HE shells were not getting inside the enemy aircraft.
German MG 131 was useful in part because it was small and light and faster firing than the Italian and Japanese 12.7mm guns of slightly more power.

 

[tomo pauk]

MK-101 was the first 'service' German 30mm but it was very heavy and slow firing so they didn't make many and they were looking for something better but not working very hard.
MK-103 used the same ammo as the MK-101 so that was a head start, They wanted a lighter, faster firing gun. They got it but it was still too heavy and didn't fire fast enough.

Both the 101 and 103 were about 140 kg without ammo and without the drum for the 101. While that is still heavy, it is not too heavy once the engine power was above 1300 HP, let alone above 1500 HP.
The MK 101 was at 180 kg with a loaded 30 rd drum.

Problem with the 103, and especially with the 101 was the bulk - neither will neatly fit within the confines of the standard German fighter of the day, be that Bf 109 or Fw 190. The belated motor-cannon modification of the MK 103 was supposed to cure that, for the needs of the Ta 152, Bf 109 and the central position of the Do 335, but how many bursts were fired by such 103s in anger is a big mistery (probably none, especially from the 109?). I'm also not sure that the synchronised installation for the Ta 152 ever managed beyond testing phase, if even to the testing itself.
Ammo size and weight is another problem.

Both MK 101 and 103 were very good as anti-tank airborne cannons when outfitted with cored shots, and would've been great as anti-aircraft guns. It would've also been a great fit on a high-performing 2-engined fighter, be that a piston-engined type or a jet, like the Me 262.

Soviet 23X115 didn't show up until the end of war. It won't fit in a MG 151/20 gun but you could make a larger gun based on the MG 151 design. Gun will be larger and heavier. This assumes you build to German (or American/British) standards. Russians built very light weight guns but they accepted that such guns would wear out very quickly.

Very true.

The MG 131 could be more effective that some people think. But we have some confusion as to what is a "mini-mineshell" round.
They used a pretty much standard, although small, HE round. Due to scaling the HE content was small.

FWIW, Germans were considering the MG 131/10 - a necked-down version with the much increased muzzle velocity so it can pierce the armor of then-modern aircraft. Pretty much shows how much they rated the HE abilities of the MG 131.

 

[Shortround6]

Both the 101 and 103 were about 140 kg without ammo and without the drum for the 101. While that is still heavy, it is not too heavy once the engine power was above 1300 HP, let alone above 1500 HP.
The MK 101 was at 180 kg with a loaded 30 rd drum.

Ammo size and weight is another problem.

The MK 101 & 103 guns were almost 3 times the weight of the Hispano guns. So the question is if the 103 gun was worth 3 times what the Hispano gun was. The 103 was certainly more powerful and longer ranged. but 7 shells a second compared to about 30 rounds per second from 3 Hispanos means possible destructive potential was very close. Extra range is hard to figure since Air to Air range depends on gunsights and aircraft steadiness and other factors. Percentage of times the extra range was useful?
For air to ground or ground to air the 103 has more it it's favor.

FWIW, Germans were considering the MG 131/10 - a necked-down version with the much increased muzzle velocity so it can pierce the armor of then-modern aircraft. Pretty much shows how much they rated the HE abilities of the MG 131.

Germans were obsessed with high velocity for armor penetration. Problem is that armor penetration is not the primary goal. Destroying what the armor is protecting is the goal.
Making very small holes in armor is not destroying things behind the armor.
The MG131 was a pretty good gun considering it's weight and size. Germans didn't use multiple installations (aside from twin cowl guns) until very late in the war. A missed opportunity?