What aircraft gun round had the flattest trajectory?

DAVIDICUS · 03-08-2005, 10:59 PM

I understand that the .50 BMG was extremely flat shooting. Were there other cartridges that shot flatter?

delcyros · 03-09-2005, 03:23 PM

How about MG 131, MK 103 and MG 213B/20mm? They should come close if not better...

DAVIDICUS · 03-09-2005, 03:26 PM

I don't know. It depends on their muzzle velocity and ballistic coefficient (how easily they can slip through the air).

delcyros · 03-10-2005, 12:37 PM

Muzzle velocity was excellent on these guns but I think, I don´t have enoug datas to post a solution. Maybe Lunatic can help with that. (My books are still packed)

The Jug Rules! · 03-10-2005, 02:58 PM

I've never heard of an mg 213? Any info on it???

CharlesBronson · 03-10-2005, 04:41 PM

The MG-213 o Mk-213 is a revolver cannon wich was developed in the very late stage of war

It was available in 2 calibers one was the 20x135mm derived from 20mm flak, and 30x85B

The rate of fire was 1100-1300, the modern series of Aden, Defa, and Mauser BK-27 was derivated from it.

The Jug Rules! · 03-11-2005, 12:33 PM

If that had made it into the war, things could have really gotten messy...

03-24-2005, 12:15 PM

The MK213 did not make WWII, it was still a good ways off when the war ended.

The MG131 13mm had poor ballistics, its sectional density of 0.256 (grams/sq. mm) is one of the poorest of all HMG's/cannon of WWII, and its velocity less than 750 m/s was not great either. The API round would have a little better SD, but lower veloctiy. This gun did not have good ballistics, but they were well matched to the MG151/20.

In my opinion, the BK5 firing AP ammo probably had the flattest trajectory. At 50mm and weighing 1540 grams, the sectional density of this round was a wopping 0.785 (grams/square mm), over twice that of .50 BMG AP round. Combine with its initial velocity of 920 m/s and it was probably the flattest shooting, longest ranged round of WWII aircraft.

The Soviet NS37 was a close contender, with a sectional density of 0.696 and an initial velocity of 890 m/s. The US M9 was similar (though very slightly less velocity and SD).

Generally speaking, it is hard for a small round to compare to a large one, as the sectional density tends to be relatively low. The .50 BMG had a high sectional density (0.383) because the round is quite long for its caliber. The .50 had the best ballistic shape of any round in WWII, but this is overcome by the huge SD advantage of some of the larger rounds (but none in the 20mm class).

=S=

Lunatic

DAVIDICUS · 03-24-2005, 01:49 PM

Good info. Thanks.

I always suspected that the .50 BMG was a flatter shooter than the Hispano 20mm's.

03-24-2005, 01:57 PM

http://members.cox.net/rg_lunatic/gunpage/

The page is damaged (part of it is missing) but the table is still good.

=S=

Lunatic

DAVIDICUS · 03-24-2005, 02:21 PM

Outstanding collection of data.

delcyros · 03-22-2006, 06:03 PM

absolutely.
Excellent work, Lunatic. I only miss the soviet UKB and the german MG 151 with 15 mm AP cartridge. I expect both to have a somehow similar and/or better trajectory compared with the 0.50 cal BMG. And both are nearly around the same weight class.

Can You tell me more about the Baltraj software?
Keep up Your good work!

lesofprimus · 03-22-2006, 06:22 PM

Dude, u do know that the post above yours was from last year right???

delcyros · 03-22-2006, 06:39 PM

correct. But I had a refreshed interest in the matter. Esspecially for the interesting part of projectiles decelerating and the maths behind. The Ballitsic-link from Lun was a quantum leap for me...

book1182 · 03-22-2006, 08:35 PM

Quote:

Originally Posted by Anonymous

Generally speaking, it is hard for a small round to compare to a large one, as the sectional density tends to be relatively low. The .50 BMG had a high sectional density (0.383) because the round is quite long for its caliber. The .50 had the best ballistic shape of any round in WWII, but this is overcome by the huge SD advantage of some of the larger rounds (but none in the 20mm class).

=S=

Lunatic

Didn't they base the X-1 off of the shape of a .50cal bullet???