20mm cannon, best, worst, specs, comparison to LMG, HMG etc.

pinsog · Aug 1, 2011

merlin said:
pinsog said:

Yes, but why would anyone want to go hunting an elephant!? Best thing to 'shoot' an elephant with is a camera - so you've got something to remember what these magnificent animals look like after being 'butchered' for their ivory tusks by poachers.

Click to expand...

Way off topic, but.....Elephants have no natural enemies. If left alone they multiply until they destroy their own food supply, essentially like 6 ton locusts they move from area to area destroying entire eco-systems and then moving into areas populated by humans and wrecking their agriculture and crop production. The only way nature has to stop this is either disease or starvation, neither is a pleasant death for an elephant. African countries are very poor, hunting being a HUGE income for them. When a white hunter from America or Europe arrives and shells out $30,000 to $100,000 to hunt an elephant, it does 3 things: 1. It helps keep the population to a manageable level 2. It feeds the local tribes who have a very difficult time obtaining protein 3. It provides the government the cash it needs to add game officers to stop poaching

When elephants begin encroaching on human developments, the tribesmen begin paoching them to protect their crops, themselves and their families

Taking a picture is all sweet and lovable and makes a person feel all gooey inside, but, hunting is what gives the species a fighting chance at survival in the modern world.

RATSEL, if you have eaten a steak, a fish, chicken nuggets, or are wearing a leather belt or shoes, then you have harmed an animal, you just let someone else do the dirty work for you.

Now, lets get back on topic: Cannon and machine guns

Ratsel · Aug 1, 2011

just got back from McDonalds.. had two double big macs, fries a milkshake..... going to safeway later to buy some veal. yummmm!!!

anyways yes, back to cannons and guns.

post76 · Aug 2, 2011

Hah,

I happen to be at McDonalds in France, and strangely they don't carry coffee or hamburgers.

wierd huh??

Anyway...

Another way to look at it, i started thinking about the effectiveness of 7.7mm and 12.7mm.
Its plausible to say the 7.7mm probably has a similar effect at 100 yards as 12.7mm would at 500 yards, but the main difference is that more
bullets are going to hit at 100 yards than at 500 yards.
Realisticly an air to air shot isn't typically made beyond 300 yards anyhow, but there are examples where some pilots shot beyond 500 yards and as far as 1200 yards with results.

Since the typical shot isn't made beyond 300 yards, and probably more likely with in 200 yards, i would rate bullet velocity and trajectory as some what of a moot point. What seems to make a bigger difference is firing time since it puts more bullets in the air. Another way to add more bullets to the firing time is to add more guns.
Now take that same 12.7mm and see how it compares to a 7.7mm at 100 yards.
Its hard to figure. Speaking of the browning M2, its nearly twice as effective as the 303 at three times the range (200 vs 600yards)
At 100 yards both guns are likely to do severe damage to an aircraft, but my thought is that the 12.7mm is probably somewhere closer to 8 times more effective at 100 yards. Since neither explode on impact they probably would never compare to the damage caused by 20mm HE rounds at that range.
my thoughts anyway.

Bon Jorney

post76 · Aug 2, 2011

A flawed analogy. The "hunter" is allowed more "bursts" of the same duration using the smaller gauge gun. Against the aircraft the 20mm guns may require a shorter burst at times. The target plane is is seen to be smoking, on fire, or large pieces falling off in 2 seconds vs the (perhaps) 3 seconds needed by a .50 cal armed plane. The hunter with his shotgun cannot adjust his "bursts", he cannot fire only 2/3s of a shell.

[/quote]

No matter what gun, pilots likely fired their guns in similar burst patterns with the exception of some of the larger M108 and M103 type cannons.

Its about what lands on target not how many bullets are fired.

Range plus deflection and ammo load will make the difference.
Example. P-47 fires 100 rounds a second, a 2 second burst sends 200 rounds.
A P-51 fires 75 rounds a second, where 3 seconds sends 225 rounds.
Thats the entire ammo load of most 20mm equipt aircraft.
Is their a 20mm load out that even puts out 200 rounds in 2 or 3 seconds??
I'm thinking late war Hispano V seen on the Tempest and F4Us.
Thats less to the point, but what i was getting at was that a pilot will likely fire similar amounts of bullets just to line up his shot and score.
Although 20mm and 30mm being more effective on impact, they might expend similar amounts of "trigger time" just to score that shot.
If trigger time were considered beneficial, then also consider the roll of the ammo.
One is designed for long range attack fighters, the other carried on short range intercept type fighters.

Jabberwocky · Aug 2, 2011

Is their a 20mm load out that even puts out 200 rounds in 2 or 3 seconds??
[/QUOTE]

Four Mk V Hispanos or MG 151/20 (750 rpm) will put out about 50 rounds per second.

Four ShVAK or B-20s (800 rpm) would increase this to about 53 rounds per second.

Four Ho-5s (850 rpm) would increase this to about 57 rounds per second. The Ho-5 was basically a M2 firing 20 x 94 mm ammunition.

In an ideal world, Molins would have been allowed to produce its version of the Hispano, which was sped up to around 1,000 rpm. This would put out 67 rounds per second in a four gun configuration.

Shortround6 · Aug 2, 2011

No matter what gun, pilots likely fired their guns in similar burst patterns with the exception of some of the larger M108 and M103 type cannons.

Its about what lands on target not how many bullets are fired. [/QUOTE]

This is true.

Range plus deflection and ammo load will make the difference.
Example. P-47 fires 100 rounds a second, a 2 second burst sends 200 rounds.
A P-51 fires 75 rounds a second, where 3 seconds sends 225 rounds.
Thats the entire ammo load of most 20mm equipt aircraft.
Is their a 20mm load out that even puts out 200 rounds in 2 or 3 seconds??
I'm thinking late war Hispano V seen on the Tempest and F4Us.
Thats less to the point, but what i was getting at was that a pilot will likely fire similar amounts of bullets just to line up his shot and score.[/QUOTE]

There are two things that counter this theory. One is that the 20mm armed fighter does fire slower than the .50s as Jabberwocky has said. They are going to fire 80-180 rounds in 2 to 3 seconds. And as you have said, it is the rounds that land on target that count, every hit from a 20mm is worth 2-4 hits from a .50 cal. While a .50 cal armed fighter will fire 200-300 bullets in 2-3 seconds the 20mm armed fighter does not have to fire 200-plus rounds over 5-6 seconds in order to get on get on target, line up and score.
the 20mm armed fighter does not continue to fire after the target is destroyed or severely damaged ( large pieces falling off, large fire, etc) which happens with fewer hits than the .50 cal.

Allied night fighters favored 20mm cannon because they could the same damage (or more) in less time than a battery of .50 cal guns. Making comparisons that run counter to this (like claiming the 20mm need to fire 200rounds in two seconds) doesn't make sense.

Although 20mm and 30mm being more effective on impact, they might expend similar amounts of "trigger time" just to score that shot.
If trigger time were considered beneficial, then also consider the roll of the ammo.
One is designed for long range attack fighters, the other carried on short range intercept type fighters.[/QUOTE]

davparlr · Aug 2, 2011

pbfoot said:
IIRC There was a test flight of F86's using 20 mm flown by the USAF in the Korean War and that were mixed with standard equiped 86's they used the 50cal armed 86's as decoys and found the cannon armed version more destructive. I have the article somewhere but in the mess of stuff I have will be hard pressed to find it

It would be interesting to read that test and understand the conditions. Decoys mostly are non or slow maneuvering vehicles and thus significantly improves probability of hits, negating 50 cal advantages. Also, I am not sure what cannon the F-86s were using at that time. If it was the M39 cannon there is no comparison to its effectiveness superiority against the 50s.

pinsong said:
The problem with the .50 in Korea was that, air combat was done at such a high altitude, the incendiary ammo wouldn't set the Migs on fire, air was too thin. The fuel burned by the Mig was probably less flammable also. At least that it what I have read.

Fire is certainly affected by altitude. IIRC, one procedure for extinguishing an inextinguishable airborne fire was to climb. So, this seems to be a valid comment.

Jabberwocky said:
I think you're understating the case for the Hispano:

A 20 x 110 round weighed 128-167 g – that's 4.5 to 5.9 oz, not the 3 oz you are using. Typically, experts like Tony Williams or Emanuel Gustin use 130 g as a round number - 4.6 oz.
Throw weight should be on the order of 210-270 oz per sec, with a 'typical' weight of about 215 oz per sec - significantly better than the M3 set-up on the Sabre.

Well, including a dumb mistake in converting to the wrong ounce (how come that multimillion dollar probe crashed on Mars, oh, yeah, they computed feet/sec instead of meters/sec), this looks correct. However, in my research, it appears that the Navy in its 110 round used 110 grams, done to increase velocity, which would make the correct number of the throw weight for the F9F 183 ounces/sec, or roughly the same as the F-86.

I also believe you're mild overstating the RoF of the Browning and understating that of the Hispano, by about 50 rps in each case.

Getting RoF rates is very frustrating. For the Hispano, several sites show both higher and lower. A Spanish site shows 720 r/min. Even less is shown for the M3. I used the USAF Museum fact sheet, but other sites show a range, or just say around 1200 r/min.

Shortround6 said:
And that means what? That the 20mm guns fired into larger area at the same distance and were more likely to miss a fighter?
If four 20mm guns were expected to damage/destroy a bomber in less exposure time than six .50s why wouldn't they do the same thing to a fighter that needs fewer hits to bring down?

I think the explanation by the AF at the Fighter Convention will clarify why the Army used different criteria for their fighters than their night fighters. I briefly state what I think are significant areas. This is by Colonel Coats from Eglin taken from the Report of Joint Fighter Conference, dtd. 16-23 Oct., 1944

…we would like to have a lethal density pattern. The most bullets going across one place at a given instance. We would like to have the smallest caliber gun that can do the job. If it takes a 22-meter to tear a Messerschmitt or a Mitsubishi apart, we want 20's…

"Another thing that comes into this matter of sighting is the training of the personnel. I believe that with more guns, you can put out bigger density pattern for the training of your personnel. When we get sights to the point where we can pull the trigger just once and hit a fellow, then we can go to the bigger calibers. It is a matter of training of pilots. The Mark 14, the gyro sight, we found didn't increase our accuracy for our control gunner to any great extent. However, it did bring the people in the middle and lower brackets up as much as 5 or 6 times better than they had shot before. I think we in the aircraft game should be worrying about the people in the middle third or bottom half…"

I think the Army figured that aiming solutions for non-maneuvering aircraft was much more accurate, justifying larger calibers, and, I suspect, most likely had more experienced pilots in the night fighters.

I will add that the the six M3 .50s with 267 rpg ( 13.4 seconds of firing time) of the F-86 weighed 353 kg, while the four M3 20mm (not WW II M2s) of the F9F Panther with 190rpg (15.2 seconds firing time) for 363kg.

It appears that weight is similar. For some reason I thought that weight was an advantage for the 20mm.

Ignoring the HE power certainly skews things towards the .50 but hardly reflects reality.

I agree, but I wanted to show that the six M3 guns put out massive firepower with 25% more rounds/min than a M61 Vulcan cannon.

I think we can stop with the SUPER.50 stuff. While it was a fast as a speeding bullet, it was not more powerful than a locomotive and it could not leap tall buildings in a single bound.

Nobody is claiming the .50 cal is a super weapon.

The chances of a .50 cal making through the Fuselage skinn are better than some people claim but the chances of it going though substantial parts of the engine are a lot slimmer.

Maybe I stated that poorly. I meant to say that a single 50 cal bullet, striking the aircraft fuselage from the turbine location up to the pilot has a high probability of disabling or destroying the aircraft. It does not need to penetrate the engine and hit the pilot. It only needs to hit the turbine, or puncture the combustion chamber, or hit the compressor, or just about any other component in the engine to cause catastrophically critical damage the aircraft. I don't think you can state that the 50 cal could not do that. Including the pilot in the high probability is probably incorrect as he seems pretty well protected.

And of course an AP 20mm projectile could not do the same thing? Or a 20mm HE or AP projectile into the engine turbine wouldn't stop it?

Obviously the 20mm can do that. The big problem with the .50 vs 20 is the probability of kill once hit. It can be much higher for the 20. However for a jet, the probability of a one hit kill or cripple of a .50 is high for the engine section, which makes up about 25% of the Mig-15, and would be similar to the 20. Outside that area, probability of kill/hit goes to the 20. But at low probability shots, the chance of a 50 cal hit is much higher due to projectiles fired. It's all probability and it certainly is far more complex than I have desire to investigate.
My argument has never been that the 50 cal is a better weapon than the 20 for air-to-air combat, just that the 50 cal was an effective weapon and efficient weapon; such that there was no big desire to change in WWII. And I certainly believe that the six .50 M3 battery on the F-86, firing over 7500 rounds/min, is not something to dismiss lightly.

Shortround6 · Aug 2, 2011

There are reports of Migs returning to base with 40-50 .50 cal hits. Maybe they were not repairable and would be considered a loss but they did return to base. The USAAF figured it took 1,024 .50 cal rounds fired to destroy a Mig-15 and the F-86 carried 1,602 rounds. It also takes 8.5 seconds to fire 1,024 rounds even with six 1200rpm guns. Granted some pilots do better than others. 50 hits out of 1000 rounds fired is a 5% hit rate which is about 2 1/2 times the percentage the Luftwaffe figured their average pilots were good for in the later parts of WW II.

The Mig-15 armament was optimized for anti-bomber work. Had they fielded a version of the Mig using Four 23mm guns instead of the one 37mm and two 23mm guns the USAAF might have seen a higher loss ratio.

The .50 cal was effective, I have never denied that. wither it was efficient in terms of armament weight to damaged caused is different and measured in those terms the .50 cal is wanting.

tyrodtom · Aug 2, 2011

Shortround6 said:
There are reports of Migs returning to base with 40-50 .50 cal hits. Maybe they were not repairable and would be considered a loss but they did return to base. The USAAF figured it took 1,024 .50 cal rounds fired to destroy a Mig-15 and the F-86 carried 1,602 rounds. It also takes 8.5 seconds to fire 1,024 rounds even with six 1200rpm guns. Granted some pilots do better than others. 50 hits out of 1000 rounds fired is a 5% hit rate which is about 2 1/2 times the percentage the Luftwaffe figured their average pilots were good for in the later parts of WW II.

The Mig-15 armament was optimized for anti-bomber work. Had they fielded a version of the Mig using Four 23mm guns instead of the one 37mm and two 23mm guns the USAAF might have seen a higher loss ratio.

The .50 cal was effective, I have never denied that. wither it was efficient in terms of armament weight to damaged caused is different and measured in those terms the .50 cal is wanting.

What was the method that the USAF used to come up with the 1024 rounds per Mig kill. It's not likely they recovered any downed Migs, let alone downed Migs intact enough to count the holes. The gun camera photos are good enough to see bullets doing damage, but a long way from clear enough to count bullet strikes.
Did they take a caputure Mig. and fire at it until, they thought they had damaged it enough. 1020, not enough. 1025, overkill. 1024, Just right. I don't think so.

So about the only way they could have come up with that figure is divide rounds expended by Migs downed. A kind of meaningless figure that tells you nothing about how many hits it takes to down a Mig.

pinsog · Aug 2, 2011

Shortround6 said:
There are reports of Migs returning to base with 40-50 .50 cal hits. Maybe they were not repairable and would be considered a loss but they did return to base. The USAAF figured it took 1,024 .50 cal rounds fired to destroy a Mig-15 and the F-86 carried 1,602 rounds. It also takes 8.5 seconds to fire 1,024 rounds even with six 1200rpm guns. Granted some pilots do better than others. 50 hits out of 1000 rounds fired is a 5% hit rate which is about 2 1/2 times the percentage the Luftwaffe figured their average pilots were good for in the later parts of WW II.

The Mig-15 armament was optimized for anti-bomber work. Had they fielded a version of the Mig using Four 23mm guns instead of the one 37mm and two 23mm guns the USAAF might have seen a higher loss ratio.

The .50 cal was effective, I have never denied that. wither it was efficient in terms of armament weight to damaged caused is different and measured in those terms the .50 cal is wanting.

I would agree by Korea, the 50's time had passed. 4 20mm would have been my preference in a Sabre
I have also read many stories of how tough the Mig15 was. It was a very tough opponant. I can't remember where I read it, but I read that a Mig15 made it back to base with something like 70 rounds in the engine. Don't know if it's true, and I can't remember where I read that.
I would also say that 1000 50's to bring down a Mig15 sounds a bit rediculous to me.

Shortround6 · Aug 2, 2011

Please note that I wrote 1024 rounds FIREDnot hits. And while it doesn't tell how many hits it takes it does tell you what the "average" number of kills per flight would be (not counting 'shares' or help from wing man). It also gives the above mentioned 8.5 seconds of firing time on "average".

I would also note that of the 4 top scoring US aces in Korea, none shot down more than 2 Migs a single flight although they may have engaged and damaged a third aircraft. One pilot did shoot down 3 TU-2 propeller bombers and Mig in one flight.

tyrodtom · Aug 2, 2011

I think a lot of the members of this forum have at one time been a member of the military. And we all remember how they liked to collect data on everything.

I'll bet a lot of us can also remember some of the ridiculos conclusions they could sometime come to after digesting that data.

Some fighter pilots are at first "spray and pray" marksman, some if given a chanch will improve, some never will. Some start out better and get even better. There are so many varibles data just can't address.

Shortround6 · Aug 2, 2011

And the ridiculous conclusion in this case was the the .50 cal MG was no longer the be all / end all in aircraft fighter armament?

The military could (and can) come up with ridiculous conclusions after digesting data, or by refusing to digest data that is presented to them.

Does this mean they shouldn't collect data at all?

And base their conclusions/decisions on what ?

Jabberwocky · Aug 2, 2011

davparlr said:
Well, including a dumb mistake in converting to the wrong ounce (how come that multimillion dollar probe crashed on Mars, oh, yeah, they computed feet/sec instead of meters/sec), this looks correct. However, in my research, it appears that the Navy in its 110 round used 110 grams, done to increase velocity, which would make the correct number of the throw weight for the F9F 183 ounces/sec, or roughly the same as the F-86.

110 g seems VERY light. Which 20 x 110 round would that be? Have you got a designation number?

The USN used both the 20 x 110 Hispano and the 20 x 110RB Oerlikon. The 20 x 110RB was marginally lighter than the 20 x 110 Hispano.

As far as I know, the US used three primary types of 20 mm Hispano rounds:

HE-I: Mk I with point fuse and Mk I/II with super quick fuse, both weighing 132 grams,
AP-T: Weighing 169 grams
Ball: Weighing 129 grams

I can find no others listed in the 20 mm manuals I have from 1942-1946.

USN 20 x 110RB rounds vary from 117 g to 123 g in weight.

davparlr · Aug 2, 2011

Shortround6 said:
A massive "wall" of 120 projectiles in the time it takes for the target to travel 800-900ft.

I have cogitated on this for a while and I still don't know the price of tea in China.

I did run a few simple probability calculations on probability of number of strikes given the probability of a strike for 47 r/sec (F9F) vs.125 r/sec (F-86).

For 2% probability of a strike per projectile, out of 47 attempts gives a 24% probability of 2 or more rounds striking.
For the same probability of 2 or more rounds striking for the F9F (24%), the F-86 will have 4 or more rounds hitting (24%).

For 5% probability of a strike per projectile, out of 47 attempts gives a 69% probability of 2 or more rounds striking.
Again, for the same probability of 2 or more rounds striking for the F9F (69%), the F-86 will have 5 or more rounds hitting (75%).

For 10% probability of a strike per projectile, out of 47 attempts gives a 96% probability of 2 or more rounds striking.
For the same probability of 2 or more rounds striking for the F9F (96%), the F-86 will have 7 rounds hitting (97%).

Obviously, the more round fired the higher the probability of hits and, as shown here, for equal probability of hits, the F-86 will deliver more projectiles, from 2x at 2% probability of a hit to 3.5x at 10%. As the planes get closer, the advantage moves in the F-86 direction. As the planes move farther apart, the advantage moves to the 20mm. However, for any distance, the probability of a equal hits always falls in favor to the F-86. Certainly, as the difference approaches 2x and below, the 20mm if obviously superior, and maybe this is the normal.
Given the Navy analysis of one 20mm equal three .50s, at about 5% probability of strike (five projectiles hitting out of one hundred), the F9F and F-86 are roughly equal in fire power, below 5% probability of strike, the F9F delivers more damage, above that, the F-86 is more effective. At least according to probability. And you know what they say about statistics!

There are reports of Migs returning to base with 40-50 .50 cal hits.

Sounds like someone bragging about the toughness of the Mig and maybe stretching it a bit. But, seeing some aircraft with battle damage, I could believe this. Sometimes there is a lucky bullet for the firer and sometimes there are lots of lucky bullets for the one being fire on.

Maybe they were not repairable and would be considered a loss but they did return to base.

How many were reported shot down by only a handful of holes? I'll bet none and not because there were none.

The USAAF figured it took 1,024 .50 cal rounds fired to destroy a Mig-15 and the F-86 carried 1,602 rounds. It also takes 8.5 seconds to fire 1,024 rounds even with six 1200rpm guns.

I can believe this. Just one three second burst trying to get an out-of-range Mig would be nearly 500 rounds. In times of stress the fingers tend to tighten, like on a transmit button or a trigger and I am sure there is no higher stress than having someone shooting at you.

Granted some pilots do better than others. 50 hits out of 1000 rounds fired is a 5% hit rate which is about 2 1/2 times the percentage the Luftwaffe figured their average pilots were good for in the later parts of WW II.

See above. 5% hit rate would make the F-86 roughly equal to the F9F in firepower.

pinsong said:
I have also read many stories of how tough the Mig15 was. It was a very tough opponant. I can't remember where I read it, but I read that a Mig15 made it back to base with something like 70 rounds in the engine. Don't know if it's true, and I can't remember where I read that.

This is highly doubtful. If so, those rounds were fired from a long way away. The centrifugal compressor used in the Mig is a tough cookie compared to the axial flow compressor, but it spins at around 12,000 rpm at full power. Hitting this with bullet and watch the fireworks. You don't even have to hit the blade just dint the casing in a bit.

tyrodtom · Aug 2, 2011

Data can only tell you so much, and it ignores something that can't be quatified in numbers, the human component, and how even individuals can vary from day to day.
What does the 1024 rounds say?
You need to carry more rounds per aircraft ? That would require a redesign.
You need more guns per aircraft, to put out those 1024 faster ? Redesign also .
Bigger, faster firing guns, so you can shoot the aircraft down quicker. Redesign .
Redesign takes time maybe even a new aircraft.

Or more markmanship training, and better gunsight. Training takes time, and redesign gunsight takes time.

Or instruct pilots to get closer, so more rounds hit target. Instant results, but hard to enforce. Also might cause a higher number of your own aircraft down because of FOD damage or midair collisions.

Or ???

Ratsel · Aug 2, 2011

well as Erich Hartmann did, hold your fire until the enemy a/c fills your windscreen. then pull the trigger. guaranteed hits.

tyrodtom · Aug 2, 2011

Ratsel said:
well as Erich Hartmann did, hold your fire until the enemy a/c fills your windscreen. then pull the trigger. guaranteed hits.

I think some of the times he went down was due to colliding with debri from his victims. So getting closer isn't a cure all.

Ratsel · Aug 2, 2011

tyrodtom said:
I think some of the times he went down was due to colliding with debri from his victims. So getting closer isn't a cure all.

that was his style, and he got results. 300+ results.

tyrodtom · Aug 2, 2011

You can't argue with success. But what works for one pilot and situation might not work so good for another.
Data would probably indicate Erich Hartmann should have died several times, but .

20mm cannon, best, worst, specs, comparison to LMG, HMG etc.

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