Mig 15 armament
Discussion
Why did the Mig 15 have 2 x 23mm cannon and 1 x 37mm? Cannon and machine guns for different types of targets I could understand, but 3 x 23mm would normally carry enough punch for anything.
Was it a compromise between parties who couldn't agree? Was it actually possible to hit a target with both sizes of shell at the same time?
Was it a compromise between parties who couldn't agree? Was it actually possible to hit a target with both sizes of shell at the same time?
I can appreciate why they wanted heavy armament, In fact I read the only reason the US stuck with machine guns on the F86 was that they had so many warehouses full of 0.5 inch guns and ammo left over from WW2. It was just the mixture that seemed an odd complication? Were they fired separately? If so, would seem to nullify the benefit of heavy armament, if not, surely the 37mm shells would behave differently from the 23mm.
The 37mm rounds were big, heavy and flew quite slowly so were mainly used in the "anti-bomber" role while the 23mm cannons were more "anti-everything else".
Due to the ballistic differences it was rare to fire them both together, usually the better ballistics of the 23mm round meant it was more useful at longer ranges than the heavier 37mm rounds so an anti-bomber engagement would begin with the 23mm's until close range where the 37mm was used instead.
The slowness of the 37mm round also meant is was pretty useless against fast moving/nimble fighters so the 23mm was almost exclusively used in that role.
Due to the ballistic differences it was rare to fire them both together, usually the better ballistics of the 23mm round meant it was more useful at longer ranges than the heavier 37mm rounds so an anti-bomber engagement would begin with the 23mm's until close range where the 37mm was used instead.
The slowness of the 37mm round also meant is was pretty useless against fast moving/nimble fighters so the 23mm was almost exclusively used in that role.
Ginetta G15 Girl said:
One round from the German Rheinmetall?Borsig MK108 30mm cannon could knock a B17 out of the sky so I'm thinking the 37mm on the MiG would knock a B29 down.
Depends where it hits of course; my recollection is that several 30mm shells were usually needed - but yes, massively more effective than the smaller calibres.I didn't know that MiG 15s fought against B29s; the Korean war is very much a forgotten war.
Simpo Two said:
Ginetta G15 Girl said:
One round from the German Rheinmetall?Borsig MK108 30mm cannon could knock a B17 out of the sky so I'm thinking the 37mm on the MiG would knock a B29 down.
Depends where it hits of course; my recollection is that several 30mm shells were usually needed - but yes, massively more effective than the smaller calibres.I didn't know that MiG 15s fought against B29s; the Korean war is very much a forgotten war.
Dr Jekyll said:
I read years ago that somebody calculated that on average bringing down a B17 took 20 x 20mm hits or 3 x 30mm hits.
Yeah it's easy for people to mistakenly think that a 30mm shell must be 50% more powerful than 20mm as it's 50% bigger but it's not as simple as that as seen by things like that calculation.As an example using the Mig-15, each 23mm round weighed around 175g to 200g yet the 37mm round weighed 735 to 740g!!!
Edited by IanH755 on Sunday 4th March 16:06
IanH755 said:
Yeah it's easy for people to mistakenly think that a 30mm shell must be 50% more powerful than 20mm as it's 50% bigger but it's not as simple as that as seen by things like that calculation.
As an example using the Mig-15, each 23mm round weighed around 175g to 200g yet the 37mm round weighed 735 to 740g!!!
How fast did they go?As an example using the Mig-15, each 23mm round weighed around 175g to 200g yet the 37mm round weighed 735 to 740g!!!
IanH755 said:
Dr Jekyll said:
I read years ago that somebody calculated that on average bringing down a B17 took 20 x 20mm hits or 3 x 30mm hits.
Yeah it's easy for people to mistakenly think that a 30mm shell must be 50% more powerful than 20mm as it's 50% bigger but it's not as simple as that as seen by things like that calculation.As an example using the Mig-15, each 23mm round weighed around 175g to 200g yet the 37mm round weighed 735 to 740g!!!
Nanook said:
texaxile said:
Layman here, in my terms what kind of effect on flying a jet aircraft would releasing such ordnance have?. Surely the recoil would throw the lightweight aircraft around a bit?.
Copied and pasted from the wiki page for the GAU-8 Avenger, which is the cannon fitted to the A10:Recoil
Because the gun's recoil forces could push the entire plane off target during firing, the weapon itself is mounted laterally off-center, slightly to the port side of the fuselage centerline, with the actively "firing" barrel in the nine o'clock position (when viewed from the front of the aircraft), so that the firing barrel lies directly on the aircraft's centerline. The firing barrel also lies just below the aircraft's center of gravity, being bore-sighted along a line 2 degrees below the aircraft's line of flight. This arrangement accurately centers the recoil forces, preventing changes in aircraft pitch or yaw when fired. This configuration also leaves space for the front landing gear, which is mounted slightly off-center on the starboard side of the nose.[19]
The GAU-8/A utilizes recoil adapters. They are the interface between the gun housing and the gun mount. By absorbing (in compression) the recoil forces, they spread the time of the recoil impulse and counter recoil energy transmitted to the supporting structure when the gun is fired.
The A-10 engines were initially susceptible to flameout when subjected to gases generated in the firing of the gun. When the GAU-8 is being fired, the smoke from the gun can make the engines stop, and this did occur during initial flight testing.[4] Gun exhaust is essentially oxygen-free, and is certainly capable of causing flameouts of gas turbines. The A-10 engines now have a self-sustaining combustion section. When the gun is fired the igniters come on to reduce the possibility of a flameout.[20]
The average recoil force of the GAU-8/A is 10,000 pounds-force (45 kN),[5][21] which is slightly more than the output of each of the A-10's two TF34 engines of 9,065 lbf (40.3 kN).[22] While this recoil force is significant, in practice a cannon fire burst slows the aircraft only a few miles per hour in level flight.[20]
This is a pretty extreme example though.
I thought it meant in terms of the stability of the aircraft itself, but apparently the Hurricane isn't much more stable in aerodynamic terms than the Spitfire (obviously he flies both types). He was saying it was the stability of the gun installation itself (combined with the close grouping of the guns in each wing) that brought about that "fact". I wanted to ask him a bit more about that, but didn't get chance.
I guess it's like the P-51 often being quoted as having incredibly smooth wings becasue they were "laminar flow", when in fact it's the wing section itself that's classed as a laminar flow type.
Anyway, off-topic.
dr_gn said:
IanH755 said:
Dr Jekyll said:
I read years ago that somebody calculated that on average bringing down a B17 took 20 x 20mm hits or 3 x 30mm hits.
Yeah it's easy for people to mistakenly think that a 30mm shell must be 50% more powerful than 20mm as it's 50% bigger but it's not as simple as that as seen by things like that calculation.As an example using the Mig-15, each 23mm round weighed around 175g to 200g yet the 37mm round weighed 735 to 740g!!!
dr_gn said:
That's interesting: I was at a RAeS lecture a couple of weeks ago, and the presenter (Shuttleworth Collection's Chief Pilot) was saying that people often state that the Hawker Hurricane was a "stable gun platform" compared with the Spitfire, without actually knowing what it meant.. He was saying it was the stability of the gun installation itself (combined with the close grouping of the guns in each wing) that brought about that "fact". I wanted to ask him a bit more about that, but didn't get chance.
Seems fair. The wing of the Hurricane is fairly agricultural and strong compared to the Spitfire. .303s in a Spit wing would vibrate and produce a shotgun effect - made worse if the harmonisation wasn't right for the range. Galland recounted this was actually useful for pilots who weren't crack shots.Simpo Two said:
dr_gn said:
That's interesting: I was at a RAeS lecture a couple of weeks ago, and the presenter (Shuttleworth Collection's Chief Pilot) was saying that people often state that the Hawker Hurricane was a "stable gun platform" compared with the Spitfire, without actually knowing what it meant.. He was saying it was the stability of the gun installation itself (combined with the close grouping of the guns in each wing) that brought about that "fact". I wanted to ask him a bit more about that, but didn't get chance.
Seems fair. The wing of the Hurricane is fairly agricultural and strong compared to the Spitfire. .303s in a Spit wing would vibrate and produce a shotgun effect - made worse if the harmonisation wasn't right for the range. Galland recounted this was actually useful for pilots who weren't crack shots.dr_gn said:
Early Hurricanes had relatively flexible fabric covered wings. I’m not sure how many saw combat before being modified to the stronger stressed skin metal versions though.
Not the covering so much as the massive 12-sided spar that runs right through the middle I suspect - but metal skinning would have made it even more rigid.Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff