20 mm in action

[Pongo]

Take the blinders off Yeager.
Its the big three ordinance failures of WW2
The sherman tank
The Mk 6 magnetic exploder on sub and surface torpedoes
and not getting the 20mm worked out as fighter armament.

In the first two the troops payed in blood.
in the last we got lucky, even though it was the easiest to solve. The freaking pony was designed for 4 hispanos.

[Krusty]

in the last we got lucky, even though it was the easiest to solve. The freaking pony was designed for 4 hispanos.

That's a very simplistic view on the larger issue.

Oh, BTW, the P-51 was designed for the british, that's why it could take Hispanos. US never ordered any in that configuration despite taking posession of some of the Brit production queue.

Cannons were not necessary for US success in the air in WW2. 50cals did the job well, and continued to do so until after Korea. The M2 50cal machine gun is still in service TODAY. That tells you how dependable a weapon it is.

[Yeager]

Its the big three ordinance failures of WW2
The sherman tank
The Mk 6 magnetic exploder on sub and surface torpedoes
and not getting the 20mm worked out as fighter armament.

Yeah, I know about the Sherman.  Im a big fan of the M26 and wish many hundreds had been made available for the invasion of Hitlers Europe and the final push against Japan as they could have been if not for the near criminal bearacracy of the Army ordinance Dept.

As far as magnetic fuses on torpedoes goes.....been there, done that.  Volumes have been written about these things.....

But the great 20mm Hispano failure?  Im not well versed on that.  

I do know the Hispanos were installed on a limited number of F6Fs and F4Us with varying degrees of success.

Of course we all know about the P38 and her well performing single Hispano supported by <gasp> four M2s...

The P-61 seemed to do just fine with her quad set up of 20mm Hispanos.  

Yet the P51 with her 4 and 6 gun M2 packages seemed to do ok, and the P47 with her smashing package of 8 M2s did pretty fair work too.  

Thats all I know.....

[B3YT]

of interest about the cannon V 50cal load out . which would have been lighter for the P47 8 .50 cal with ammo (380 RPG?) or 6 20mm with 120 RPG? or even 4 with 120 RPG?   

those are roughly the equivalent in fire power . it's only hypothetical . because the hurri IIc , typhoon IIb , tempest , Whirlwind, and spit Vc seemed to do quite well with the 4 X 20mm (I'll also add the spit 21 there) , and mossie. Don't forget the A36 Apache for you Americans.

If the 20mm load out  would be lighter then it would have helped with roll rate as the weight would be moved inwards on the wing needing less energy to start the roll and to maintain it. 

[Krusty]

A single cannon is about the equivelant of a battery of 3 50cals. M2 Cannons are much heavier than 50cals.

On top of that, only one group of P-47Ds ever flew with "425 rpg" setup and that was for ground strafing. Most (Ds and Ns too) had the "267 rpg" setup (those are in quotes because I don't know the real terms -- combat vs overload vs special load, etc). P-47M never flew with the heavy load, and probably only ever flew with 6 guns and 267 rpg.

A 4x or 6x Hispano setup like you mention, with hundreds of rounds per gun, is going to weigh anywhere from 500lbs to 1000lbs. I seem to recall doing the math regarding Hurr2a, Hurr2B, and Hurr2Cs, and coming up with about 500 lbs and change for the quad hissos there, and that's with the minimalistic ammo loadout on hurr2cs.

[B3YT]

ok so say 60 rpg more than enough for a fighter.  and enough for ground attack .

[humble]

You have to put the "failure" label for the Sherman (which I don't disagree with) within the context of designed use. The US doctrine did not actually envision "tank on tank" combat. The US intended to engage enemy armor with its TD's while US tanks supported infantry operations. So initially the issues (1942/43) have to do with deployment in conflict with doctrine and the unexpected use of the 88mm dual purpose gun in a forward deployed role. The lack of a suitable gun tube is a greater failing then anything else. If you move forward to 1944 the change in doctrine resulting in the use of the 2 "heavy" divisions changed the nature of armored combat and really enabled US achievements (at an obviously very high sustained rate of attrition). However the Jumbos suffered minimal casualties even engaging tigers and the easy 8's were reasonably capable as well. No question the M26 should have been in production much sooner but the M4 wasn't a failure as much as a 1942 tank in front line service in 1944...like saying the F4F was a failure...

[Yeager]

good point.  Imagine 150-200 M26s during the Normandy breakout

[W7LPNRICK]

Warning! Not a hi-Jack...when I was in Korea a very young ignorant airman thought it would be cool to bring a live 21mm F-4D Gatling gun pod round to the barracks to show his non-ammo buddies. When he had walked on the carpet for 30-40ft and reached for the door-knob {Boom! } the static spark ignited the electronic primer and removed his hand and injured several bi-standers, one of which was trying to stop him.  Remember, It's real out there. 

[Yeager]

F4 gunpod 21mm?  Electronic primer?  Ouch!  munitions are designed to be lethal.  Treat them as such.

When I was a youngster our next door neighbor, a few years older than I, had an affection for all things containing two words "military explosive".  Since we lived near two different military installations he managed to find a live impact range and picked up two 40mm grenade duds and placed them in his coat pocket.  All it took was him jumping across a small depression in the landscape and they detonated.  Another neighbors mom was a nurse on duty at the base hospital and was part of the receiving team awaiting his mortal remains.  There was nothing could be done for the lad.  He was gutted from the sternum to the pelvis.

[thorsim]

one really good reason not to arm the USAAF fighters with cannons is the likelihood of FF caused by trying to kill an attacker ...

with the armor on the buffs it is unlikely that several stray .50s would ruin a bomber crew's day ...

OTOH several HE 20 or 30mm rounds likely would cause some serious problems to any aircraft ...

besides "iffin it aint broked donne feex (gon an brek) it" ...

[W7LPNRICK]

I'm not sure why the ammo guys called it a 21mm, all the books say 20mm. Matbe because it was distinctly different from the original 20mm anti-aircraft rounds...?

[Pongo]

We have indeed had some fun with this.

I can post numbers that show how much more effective pound for pound a hispano battery is then a 50 cal battery if we really want to discuss it.
Like I said earlier, it was just luck that allowed the 50 to get out of WW2 with people able to try and defend it as the primary battery of a fighter in 1944. Luck that all the enemy bombers where gone or not  able to be deployed.
The reason that the US ended up with primarily 50 cals is that they scored an epic fail at producing a good hispano, or mg 151 which they also played with. Much less matching the excellent russian 20mm.
There were many many many 1000s of unused hispanos in ware houses in the states because the army rightfully wouldnt trust it as an exclusive weapon on its fighters, but that trust is nothing to do with the hispano per say, its to do with the US version and its ammo.

As to the shermans, it is unfortunate that the Germans didnt play along with us doctrine from the battle of france time, but very fortunate that they let the British have a fully operational Tiger in 1942!!!
they used 88s in direct fire in 1940. And you dont need an 88 to easily kill a sherman, its totaly vulnerable to 75mm L48 fire. Its vulnerable to 50mm L60 fire!
Comparing the failure of the Sherman to the Wildcat is like saying the hellcat wasn't made. Not only was it made, it was designed made BEFORE its tiger showed up so to speak.
Similarly, its not that the Shermans Hellcat wasnt attempted, it was worked on in 1941. But the technical politics and infighting sabotaged it just like the hispano and the torpedo.

And it is mostly only tragic in comparison to the excellence of design and integration we see from so many US war fighting equipment.

To say the 50 was preferred as a fighter battery to any 20mm is like saying that the Dauntless was preferred to any dive bomber, just because it was preferred to the Helldiver.

I am not saying the 50 was a failure, it worked. Its deadly, but the development of a US 20mm fighter gun was a complete failure. And its not that it wasn't wanted or tried. And that is starting with a fully functional product!

[Karnak]

The US manufacturer of the Hispano built it to artillery tolerances because it was a "cannon" and that caused a lot of its problems.  They also refused to adopt the British solution to the jamming issue.  I recall reading the conclusion of a British report after testing the US made Hispanos.  They said the finish on it was much better than the British Hispanos, but that it suffered such a high stoppage rate as to be totally unsuitable for service, something like ten or twenty times the stoppage rate of British made Hispanos.

[Yeager]

As long as they work flawlessly in game I'm good with it