Strafing question

[Opsboi]

Rather an interesting bit of whimsy in one of the other chatrooms I occasionally take a quick half in - main topic Welsh rugby, but that's by the by - I'd be interested to see if there's an answer

Q - "When watching war films with planes shooting at say a column of people on a road the bullets from the plane always look like they hit the ground about 10 to 15 feet apart.
But that's just for effect shirley?
Anyone calculate the spacing on the ground of these bullets if say the plane is flying at 240mph and the m/c gun fires at say 420 rounds per minute?"

A -"Machine guns are designed and built to be inherently inaccurate in order to give a "cone of fire" instead of all the rounds landing in the one spot. The "cone of fire" gets larger the longer the range you're firing at. So I don't think it's possible to work this one out."

The original questioner conceded that he should have added the word "theoretical" somewhere, and I suggested he also needs a theoretical altitude

Any ideas, aviators?

[Boac]

Never thought about it! However, 240 mph =88 fps x4: 420 rounds per min =1/7 th of a second between rounds.

Thus between each round a/c has moved 4 * 88/7 ft. = 50 ft.

[Pontius Navigator]

(88*4)/(420/60)/n

Where n=number of guns.

[unifoxos]

Times cosine of angle of dive.

[Pinky the pilot]

the m/c gun fires at say 420 rounds per minute?"

Awfully slow firing MG at that rate.

The Colt Browning 303 fitted to the Hurricane and Spitfire fighters had a cyclic rate of somewhere near 1200 rounds per minute.

From memory, even the .50BMG fitted to the American a/c had a faster rate of fire.

[izod tester]

Canon fire and not machine guns, but the attached shows the fall of canon fire during an attack by Mosquitoes on a ship:

https://www.iwm.org.uk/collections/item ... hotographs

[Opsboi]

Thank you, all!

[AtomKraft]

A Vulcan 20mm fires 100 times a second in its first second.

[Pontius Navigator]

So typically 100 rounds over 800 feet.

[boing]

I'm not sure what you folks are getting at here.

With a modern gunsight that compensates for so many variables if the pilot could hold accurately on the target for a one second burst all of the rounds will go into the same small hole, there will be no dispersion. That's what sights are for. But, if he holds on to the target too long, target fixation, he will end up in the same hole as the projectiles. So, eventually he pulls out of the dive which will, if he has any ammunition left, cause the impacts to track along the ground.

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[Boac]

I understand to OP referred to one of the 'strafing' films along a column of people, not 'target shooting' to which you refer.

[TheGreenGoblin]

If you are going to do a bit of strafing, then you might as well be in one of these...

[TheGreenGoblin]

There is some amazing genuine WW2 strafing footage online...

[Pontius Navigator]

WW2 was essentially a black and white war so seeing it in colour is slightly surreal. Not only that, the pastoral scenes appear so peaceful in contrast to the film of bomb explosions and incendiary fires.

[ian16th]

WW2 was essentially a black and white war so seeing it in colour is slightly surreal. Not only that, the pastoral scenes appear so peaceful in contrast to the film of bomb explosions and incendiary fires.

Thanks to Agfa, there are more colour film archives from the German side that from the British.

Of course after Pearl Harbour, when Hollywood took an interest, there are plenty of 'Merican records.

[boing]

If you look carefully the films show exactly what I am talking about. There are what you could call "point" targets and "area" targets. Point targets would be railway engines, trucks or individual parked aircraft, for those you make a straight approach to be able to use the sights accurately and all of the rounds fired go into a relatively small area before you break off the attack. Area targets would be troop concentrations or dispersed targets such as a line of railway carriages on a length of track. These you would attack by choosing the best target first then adjusting the point of aim so that the rounds "walk" along the ground covering a larger area.

The technique used depends on the target and the munitions you are firing. For example, with the larger caliber cannons used against armoured targets and ships you do not have enough ammunition to waste it on dispersed targets, you must use aimed fire to be effective. If you are loaded with plenty of 0.303 rounds you can afford to spread them around and they will be effective against personnel and soft vehicles.

Wikipedia has quite a good basic explanation. https://en.wikipedia.org/wiki/Strafing

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