Author Topic: The American Hispano (Read 612 times)

Tony Williams · « **on:** February 09, 2003, 01:45:33 AM »

I have added an article to my website concerning the problems with the American 20 mm Hispano aircraft cannon in WW2, and why it didn't see more use. See: http://www.quarry.nildram.co.uk/US404.htm

Tony Williams: Military gun and ammunition website and Discussion forum

Karnak · « **Reply #1 on:** February 09, 2003, 02:38:28 AM »

Interesting read.

I don't think that the .50 cal vs. 20mm debate among WWII aviation buffs will ever go away and most of us are biased. I like your document, but given that I prefer the 20mm Hispano Mk II to the .50 calibre Browning that is not surprising. I'm sure that people who prefer the .50 calibre Browning over the 20mm Hispano Mk II will not view the document as favorably.

Of course, both reactions are the antithesis of good research.

(BTW, when is your aircraft gun book going to be published?)

brady · « **Reply #2 on:** February 09, 2003, 08:16:37 AM »

TY for posting that Tony I found it very ilumanating, I had always understood that US 20mm Hispaanos were unreliable but I had never fully appricated the extent to which the whole prodject was FUBARed by the US, it is almost laughfable, tradgical so. Man if they model Historical gun jams in the ToD the Hispano will be neuatered(at least the US one will).

So the early P38's used the unmodified M1's the ones with the larger chamber corect, thats why their reliabality was notoriously bad correct? Then I supose this problem presisted in the Later model P38's for the same reasion that the Navy guns had problems?

Also, So it is true that by far and large the British guns had no serious relialablity issuues? That is to say ones that the British made, How many if any US guns were sent to England and used in British planes?If they were did they suffer the same relaliblty issues?

") The ballistics of the projectile can stand much improvement. It is believed that ballistics similar to that of the Caliber .60 projectile can be closely approximated."

I find this particulary interesting, All Hispanos in AH preform prety much the same balisticaly, they are very consistant and relilable, they have a very flat tradjectory and have almost the same balistics as the 50cal Browning, so close in fact it hardely warents concern when they are used together.

Tony Williams · « **Reply #3 on:** February 09, 2003, 09:02:18 AM »

Brady, I have no information about the reliability of the Hispano in the P38. OTOH, I believe it did have a mechanical cocking handle which the pilot could operate to clear misfires, something the wing-mounted Navy guns couldn't have.

The reliability of the British guns was around one failure every 1,500 rounds, compared with one per 4,000 for the .50 Browning. However, I don't have a comparable figuire for the US Hispano.

The question of the British use of US-made guns is interesting. According to US stats, a large number of Hissos were made for export and its hard to imagine who else would have made much use of them, but the incompatibility of chamber size and ammo makes me wonder...

The poor ballistics of the Hisso were down to a very blunt shell shape. The last US (postwar) version had the lighter (102g instead of around 130g) and more pointed shell used in the M39/M61 ammo, and this was fired at 945 m/s.

Karnak, the book is supposed to be out next month. Watch this space

Tony Williams: Military gun and ammunition website and Discussion forum

brady · « **Reply #4 on:** February 09, 2003, 09:40:05 AM »

Could you be presuaded to elaborate further on the balistices of the 20mm M2 compared to the US 50 cal M2? you See in AH they are quiet simmilar, and corect me if I am wrong but it apears that from your post they may indead be quiet different.

For example the F4U-1C 20MM Hispano M2 ammo load out would of been...the 130Grain blunt nosed ammo corect? I am also curious as to the chain load out, i.e. AP HE, Tracer ect.

Further did P38 or P61 for that matter fire the same ammo as the Navy did.

F4UDOA · « **Reply #5 on:** February 09, 2003, 03:18:53 PM »

Tony,

I'm curious about a couple of things you said.

First you mentioned the SB-2C having more air kills than the F4U-1C. Do you have a breakdown of kills by type? I would be curious to see those numbers.

The other concerns your comment about the reliabity of the M-3. I read an artical by Guy P. Bordelon who was the only Navy Ace of Korea flying F4U-5N's. He mentions he was send to France to help the French adjust to the F4U's. He said that the French could never get the 20mill to fire because the weapon had somewhat tight tolerance and had many tourque sensative adjustments and that the French would just tighten everything as far as they could. He says that everytime he went up that the guns would work fine and then the French pilots could still not get them to fire. I believe the artical is in "F4U Warbird History".

Also note that the Honduran AF had no trouble with the M3 20mil in 1968 shooting down three Salvadoran birds with the same F4U-5.

F4UDOA · « **Reply #6 on:** February 09, 2003, 03:32:45 PM »

Tony,

Here is an excerpt from an artical on a test peformed in Korea by the AF and Marines.

For those uninitiated in the Korean War arguments over the difference between .50 caliber ammo the B-26s/F-84s used and the 20mm HEI that the Marines used, they scheduled a test in Taegu in the summer of 1951 between USAF F80 Shooting Star and F-84 Thunderjets with 30 rounds of 50 caliber per gun. The Marine F4U-5N had only 10 rounds of 20mm HEI. The F4U-5N was flown by Lt. Roland of the VMF(N)-513. USAF aircraft attacked their truck carrier targets with .50 caliber and caused the max damage of a "the kapok seat of one carrier began to smolder." The F4U-5N snapped the frame of the truck almost in half; blew one of the front wheels off; and destroyed the flatbed. On his second run, he hit the cab and snapped the steering column in half. Despite these tests, the USAF persisted in the use of .50 caliber ammo simply because there was a lot of it left over from World War II. Even today many people feel the USAF MiG kills would have been much higher if they had used 20mm HEI instead of .50 caliber as Soviet jets were literally riddled with holes from .50 caliber...but continued to fly and returned to base.

Here is the whole artical.

http://www.kalaniosullivan.com/KunsanAB/VMF513/Howitwasa1ac.html#Corsair:

Tony Williams · « **Reply #7 on:** February 10, 2003, 12:05:08 AM »

Quote

Originally posted by brady
Could you be presuaded to elaborate further on the balistices of the 20mm M2 compared to the US 50 cal M2? you See in AH they are quiet simmilar, and corect me if I am wrong but it apears that from your post they may indead be quiet different.

For example the F4U-1C 20MM Hispano M2 ammo load out would of been...the 130Grain blunt nosed ammo corect? I am also curious as to the chain load out, i.e. AP HE, Tracer ect.

Further did P38 or P61 for that matter fire the same ammo as the Navy did.

The muzzle velocities were very similar and up to 300m or so there would probably have been no significant difference, but the blunter shape of the 130 gram shell meant that it would have fallen further behind at longer ranges.

I don't know about the US ammo loadout. The British used 50:50 HEI:SAPI, but the US didn't use SAPI AFAIK.

Tony Williams: Military gun and ammunition website and Discussion forum

Tony Williams · « **Reply #8 on:** February 10, 2003, 12:06:57 AM »

Quote

Originally posted by F4UDOA
Tony,

I'm curious about a couple of things you said.

First you mentioned the SB-2C having more air kills than the F4U-1C. Do you have a breakdown of kills by type? I would be curious to see those numbers.

I didn't say that, Chinn did! Unfortunately he gave no further details. Thanks for the info about M3 use.

Tony Williams: Military gun and ammunition website and Discussion forum

Soulyss · « **Reply #9 on:** February 10, 2003, 12:38:38 AM »

Quote

the United States Navy was the only branch of the service actually placing Hispano Suiza cannon in planes in great numbers and demanding that aircraft designs of the future include 20-mm in lieu of lighter machine gun armament.

I find this ironic, since I figure it's probably safe to say that the .50 cal was much more effective against the Navy's principle oponents than the AAF's.

brady · « **Reply #10 on:** February 10, 2003, 08:57:59 AM »

TY Tony for being so helpfull in increasing my(and our) understanding of this issue. I have one last question if you dont mind:

Did the US Navy and The USAAF, use the same ammo?, the US Army Ordance Manuals I have looked at were not to specific on this point.

F4UDOA · « **Reply #11 on:** February 10, 2003, 09:24:54 AM »

Tony,

This is what I was refering to from your artical.

Quote

Statistics on enemy aircraft shot down in World War II credit the AN-M2 in SB-2C aircraft with destroying few enemy aircraft. The F4U-1C planes brought down an even smaller number. However, it must be remembered that the primary mission of the SB-2C was not to shoot down aircraft.

I was just wondering if you had the breakdown of kills by subtype?

Virage · « **Reply #12 on:** February 10, 2003, 10:06:32 AM »

Thnx for another interesting article.

Tony Williams · « **Reply #13 on:** February 10, 2003, 08:39:29 PM »

Quote

Originally posted by brady
TY Tony for being so helpfull in increasing my(and our) understanding of this issue. I have one last question if you dont mind:

Did the US Navy and The USAAF, use the same ammo?, the US Army Ordance Manuals I have looked at were not to specific on this point.

I don't know for sure, but I would say almost certainly yes. The AN-M2 Hisso was that rarity, a joint Army-Navy project (that's what the AN meant) so if the guns were common the ammunition was likely to be.

Tony Williams: Military gun and ammunition website and Discussion forum

Tony Williams · « **Reply #14 on:** February 10, 2003, 08:40:14 PM »

Quote

Originally posted by F4UDOA
Tony,

I was just wondering if you had the breakdown of kills by subtype?

No, the only reference I have is the article which I published.

Tony Williams: Military gun and ammunition website and Discussion forum