Author Topic: weapon comparison (velocities)  (Read 518 times)

Offline Toad

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weapon comparison (velocities)
« Reply #15 on: July 04, 2001, 10:36:00 PM »
Niklas,

All you need to figure ballistic coefficient is a "near velocity" (0 range) and the velocity at 200 yards (600 feet).

Do you have any of this for the Hispano HE or any of the MG 131, MG 151, Mg151/20?

If so we can get good trajectory/velocity/energy.
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Offline Vermillion

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weapon comparison (velocities)
« Reply #16 on: July 05, 2001, 07:31:00 AM »
I have original source data for most (if not all) the major American Ammunition types from WWII.

Here is a link to the 20mm information.
 http://www.vermin.net/temp/TM9-2200-20mm.pdf

For the American version of the Hispano ammunition the ballistic coefficent is

HEI : 0.452 lbs/sq inch
AP-T: 0.613 lbs/sq inch
Ball: 0.457 lbs/sq inch

I also have the same data for the .50's and .30's but its not scanned in. If your interested, send me an email and I'll look it up for you.

I've also acquired a large source of data on the German and Japanese Ammunition, but I haven't had time to look thru it, so I'm not quite sure what all I have.

Offline Toad

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weapon comparison (velocities)
« Reply #17 on: July 05, 2001, 08:37:00 AM »
Excellent stuff, Verm.

I'd really be interested in the BC's and velocities for the MG 131 and MG 151 (both calibers).

I'd love to run those through and finally see a good trajectory data for them.

I do like the way the calculator got .582 for the BC and your actual shows .613. Not bad for working backwards off charts that are hard to read.

Thanks!
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Offline Pyro

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weapon comparison (velocities)
« Reply #18 on: July 05, 2001, 09:19:00 AM »
Niklas,

I still don't see what you describe.  Here is the same test with the 36" M2 that's used in airplanes.

 

Offline Jigster

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weapon comparison (velocities)
« Reply #19 on: July 05, 2001, 04:18:00 PM »
Pyro I believe he's refering to what the tracers are doing, and apparently the tracer rounds aren't slowing (visually) down accordingly as time in flight progresses.

[ 07-05-2001: Message edited by: Jigster ]

Offline Naudet

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weapon comparison (velocities)
« Reply #20 on: July 05, 2001, 05:15:00 PM »
Jigster i doubt that tracer and rounds are calculated seperatly.

If u see a tracer hit the tgt it hits it in the game, this may accure at a higher visual speed as in real life, but hit/dmg data seems to refer to the correct speed it would have at this range.

But what really makes me wonder is the time the GE guns need to fly through sector one compared to the allied guns.
If u compare the data Niklas got, the MG151 needs about 2.2x the time for sector one than hispano/o.5 cal while MG131 needs about 2xtime of hisp./o.5 cal.

This is, sry, when i say it even at best not possible! OK the GE guns have a slower muszle velocity but they are far away from being 50% slower than the allied bullets.

Also the MG151 should be faster than the MG131 cause the muszle velocity of the MG151 if 750m/s compare to 730m/s of the MG131 if i remember right.

If we also assume that the hispano round is about 900m/s and the 0.5 cal 860m/s, the difference for sector one should more likely be MG131 1.3x the time of of hispano and MG151 1.2x time of hispano for sector 1.

Also this relative speed advantage of the allied guns increase to sector 4 in which MG151 is 3 times slower than hisp.

No wonder why any shoots beyond 400 yrds are only related to luck and why deflection shoots even within 400 yrds are real difficult to do. All assuming that Niklas data is right.

Now a few questions to Pyro, can u do the same "impact" test with the 4 weapons mentioned in Niklas test?

Are the tracer speeds directly linked to bullets calculation in AH?
 
If the impact tester shows 2000 ft/s impact speed, does the bullet actually travel at 2000 ft/s in the game, or is it possible that it is acutually slower or faster?