P-51 Mustang w/50cal BMG...
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No4Mk1*
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Relative to ground the bullet has an extra ~600fps. The air pressure only affects the bullet in air, not muzzle velocity for all practical purposes
Hardtarget
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I don't know the answer to your question, but... you combined two of my favorites...the P-51 and big guns...great!
Some great fighter planes in WWII !
Mark
Some great fighter planes in WWII !
Mark
If that airborne Mustang's bullet strikes an enemy plane moving towards it at 400 mph, the bullet's impact velocity will be about 1200 fps faster than if both planes were parked on the ground facing each other.
Enemy plane going straight away at the same speed, well, you can figure that out the bullet's impact velocity pretty easy, now. Right?
Enemy plane going straight away at the same speed, well, you can figure that out the bullet's impact velocity pretty easy, now. Right?
My neighbor a while back was a B-17 pilot in WW II. He told me about his first encounter with the P-51. He said that, normally, they routinely picked up their fighter escort at a certain point on their mission. He never knew how many or what planes they would be. He said the fighters usually had to turn around for lack of fuel at the time they needed them most near the target. Sometimes the German fighters would try to harass them all the way in, but they mostly waited until they knew the fighters had left, then began their attacks.
On this particular day, my neighbor got a message from some spotters that over 40 German fighters were headed to intercept them. He said they knew this was going to be bad. After a while, he caught some glints of planes above and in front of him. He thought it was the German fighters, assuming that his own cover had left. Then, some German fighters appeared ahead of him, and those "glints" he had seen dove on the Germans and began shooting them to pieces. His co-pilot said, "What in the Hell is that?" My neighbor said, "I don't know, but I ain't complaining." It was P-51's. They lost no planes to fighters that day, and my neighbor said there is no telling how many Germans got shot down.
On this particular day, my neighbor got a message from some spotters that over 40 German fighters were headed to intercept them. He said they knew this was going to be bad. After a while, he caught some glints of planes above and in front of him. He thought it was the German fighters, assuming that his own cover had left. Then, some German fighters appeared ahead of him, and those "glints" he had seen dove on the Germans and began shooting them to pieces. His co-pilot said, "What in the Hell is that?" My neighbor said, "I don't know, but I ain't complaining." It was P-51's. They lost no planes to fighters that day, and my neighbor said there is no telling how many Germans got shot down.
ClickClickD'oh
Member
Watch out for fun and games while firing your guns in a steep dive..
Because you might shoot yourself down.
Because you might shoot yourself down.
My dad went to high school mid 50's in Los Angeles in the area where North American Aviation had one of their plants building P-51's. After jets started becoming commonplace NAA donated a pair of P-51's to my dads high school aviation mechanics program complete with working 50 cal's. Different times.
Sunray
Member
Physics says the bullet will start out at 400 MPH while in the belt then accelerate to MV 2,910 ft/s(about 586 mph.) for M33 ball.
However, there's this. "In extreme war emergency the airplane can be dived to a Mach number of 0.83 (400 m.p.h. Indicated Airspeed at 25,000 ft.), if a very gradual pull-out is made." Apparently from a Wright Field test.
However, there's this. "In extreme war emergency the airplane can be dived to a Mach number of 0.83 (400 m.p.h. Indicated Airspeed at 25,000 ft.), if a very gradual pull-out is made." Apparently from a Wright Field test.
MutinousDoug
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MV 2910 ft/s x 60 sec=174,600 ft/min x 60 min=10,476,000 ft/hr / 5280 ft=1994mph
Tinpig
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Very interesting link. Thanks
Tinpig
Back in the late 40s and early 50s they did testing with .50s and 20mm guns and found the .50s performed better at altitude. Unfortunately the reason they were testing was to arm the B-36 Peacemaker, which ended up with the inferior 20mm guns. I just finished a great book on the subject. I'll try and dredge it up.
tark
Member
Sunray, better double check your math. 2910 FPS translates to a lot more than 586MPH. The speed of sound at seal level is a bit under 1200 FPS, which translates to just over 700 MPH.
The whole nine yards.Speaking of P-51s and .50 cal, here is what they looked like before lifting off to protect our bombers.
L.W.
lysanderxiii
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The muzzle velocity would be unchanged...
lysanderxiii
Member
Performance of the machine gun or the terminal performance of the projectile?
Between the two, the terminal performance of a 20mm projectile, filled with HE is vastly superior to the terminal performance of a solid .50 cal slug (or an incendiary).
Until the advent of the M39 and later the M61, the US had trouble getting a reliable 20mm cannon. We never could get the Hispano-Suiza design to work reliably enough for our liking, not that we didn't try... the M1 20mm, the M2 20mm, the T31 20mm, the M3 20mm, the M24 20mm and the Navy's Mk 12.
From 1952 inwards (the year the M39 was introduced into service), the .50 caliber was never seen on new designs (the B-52 was the last design to use the venerable AN/M3 .50 cal. Part of the reason the .50 cal was still viable on the B-52 was the fire control radar, which tracked the bullet path and the target path, and given that if the target was in the firing cone behind the B-52, he was committed to thew tail chase and not likely to be able to maneuver enough to avoid being hit, or unaware of just how far back a .50 cal could reach. They could reach back almost as far as some heavier Soviet cannon could reach forward. Namely, because a .50 cal slug with half its muzzle velocity (about a mile back) hitting an aircraft going 600 mph is the same as a .50 caliber slug hitting a stationary target at 600 yards/
Neither the B-36 and the B-47, had the fire control nor the speed to make .50 caliber machine guns viable as defensive armament. Especially when you consider the Soviets were arming MiG-15s with a 37mm cannon in addition to two 23mm cannon.
The projectile performance at high altitude (above 40,000 feet). I have the book sitting here now, but I don't have time to go through it at this exact moment. The book is all about the B-36 development and deployment process and it goes into great detail on weapons testing at altitude. As originally built, the B-36 was intended to have .50s and they even proposed a 37mm armament before settling on the 20mm.
Testing was performed using radar to determine the ballistic performance of various cartridges at altitude.
Testing was performed using radar to determine the ballistic performance of various cartridges at altitude.
Kaeto
Member
How about 10 .50 cals and a 75 mm shooting at you?
Dain Bramage
Member
That's twelve .50 cals. There are two more blister guns on the other side.
I once (for a reason I now forget) described metal linked belts on aircraft guns to a co-worker, mentioning that in fighters the fired cases and links were dropped down a chute and out of the plane.
"But that would be dangerous, suppose they hit someone on the ground", said my modern "safety first" friend.
Jim
"But that would be dangerous, suppose they hit someone on the ground", said my modern "safety first" friend.
Jim
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