P-47/51 deflection shots into the belly of the German tanks,reality

On Wed, 13 Aug 2003, Paul J. Adam wrote:

In message , Kevin
Brooks writes
The fact is that the USN did not
switch to 20mm during WWII, ahead of the USAAF, as Paul stated with
his "difference between the Pacific and Euro theaters" comment.

How come the F8F Bearcat was designed and built with four 20mm guns,
then?

The original F8F-1 was armed with 4 x .50 cal mgs. The 20mm cannon were
introduced with the F8F-1B models.


Cheers,

"Paul J. Adam" wrote in message ...
In message , Kevin
Brooks writes
"Paul J. Adam" wrote in message
...
However, to maintain lethality it had a higher rate of fire, so it ate
that ammo faster.

I believe you'd go Winchester with the old 20mm in WWII era aircraft a
bit faster than the .50 cals did.

Checking, that's true - on the other hand, you did a lot more damage
with the 20mm guns. I recall a vivid account from a Hurricane pilot
flying night intruder over France, describing his firing pass on a
German bomber in a Hurricane IIC; and his startled surprise at how the
aircraft caught fire and went out of control almost at once, compared to
the long 'squirt' needed with machine-gun fire.

Yeah, and the .303's in the Hurricane were not .50 cals, were they? I
believe one can also find plenty of examples of MG fire quickly
destroying both german and Japanese aircraft during WWII (i.e., all of
those large deflection snap shots).


Wasn't that one of the reasons the
USAAF and USN stuck to the MG's during WWII?

I doubt it, or the RAF would have stuck with .303".

I do believe ammo volume was a concern for the USAAF; one has to
wonder if the 20mm was so invaluable, why did it get dumped from so
many aircraft? I belive a lot of P-38's dumped them, as did the B-29
in its tail armament (we went through this a while back--issue being
both weight *and* performance problems).


I think the reason was that the .50 (and the factories to make it and
its ammunition, and the ground crews trained to service it...) was
available, effective, and varied from adequate to excellent depending on
the task it was asked to do.

I belive you are correct, but I think you are also ignoring the fact
that there were other factors as well.


The USN switched to 20mm guns for its new-production fighters and
dive-bombers (the dive-bombers arrived before the end of the war, the
fighters mostly didn't) but the USAF didn't.

Partly correct. The USN "sort of" switched, as best I can figure; they
produced MG armed fighters to the very end of the war, I believe (even
the vast majority of the -4 series of Corsairs were MG armed). The
20mm did not come into large scale USN/USMC fighter use until after
the war, and even then they retained MG armed aircraft like the
Corsair through the Korean conflict.


Miss someone by a foot with a .50" bullet and you've got a crater. Miss
by a foot with a 20mm HE and you've got a good chance of a casualty.

Fact is that most gun runs were directed at equipment, and not
specific crunchies.

Burst effect is handy when strafing groups. It also ups lethality
against a lot of soft targets (using HEI) and harder targets like APCs
and self-propelled guns (using AP).

The 20mm of the day (not the same as todays more powerful charges,
both propellent and filler wise) was not the big hitter that you
apparently believe it was, IMO. Plenty of German vehicles, including
armored ones, were killed by the ol' .50 cal, too.


Another unassailable fact is that aircraft like
the P-47 were extremely effective strafers during WWII.

Not in question. But would the P-47 have done better with four or six
20mm vice eight .50s? (or twelve .30s, for that matter?)

I doubt it would have really been any more effective with the cannon
armament.


To take a different example, the US Army replaced the M-1 with the M-14.
Does that mean the M-1 was a flawed, ineffective weapon and a dangerous
liability to the troops carrying it? Don't think so, somehow.

Careful. By that approach, we went to the 5.56mm over the 7.62mm
because volume of fire became more important than hitting power--what
does that say about the .50 cal vs 20mm argument?


The P-51 wasn't much used for ground attack because of its vulnerable
cooling system ("stick a pin in a Mustang and it would boil to death in
five minutes").

I'd say it was not as prevalent in that role as the P-47, but it was
indeed used quite a bit in the air-to-ground role. As the Luftwaffe
became less of a factor over Germany, the Mustangs were often allowed
to go low and stike targets of opportunity on their return, according
to my reading.

That's not the same as dedicated strike; it's using fighters with useful
remaining fuel and ammo for targets of opportunity.

And while your point about the P-51's radiator is
valid, it did not stop the USAAF from using the Mustang in the
air-to-ground role; the A-36 ring a bell?

What's the relative numbers of A-36s and P-47s in USAAF service, and a
sortie count for each?

Hey, no argument that the P-47 was the better CAS/BAI platform--but
the P-51/A-36 was indeed used for ground attack during WWII, and in an
amount that IMO exceeds the "wasn't much used" that you have
attributed to it.


Not to mention the
air-to-ground use of the Mustang in Korea by the USAAF, RAAF, ROKAF,
etc.

Driven by the fact that they had F-51s available to reactivate rather
than a superiority for the mission.

Who cares what drove it--it was used in that role.


Say not "the .50 was the best", say rather "the .50 was a solid
performer and good enough that the improvement from a change was
outweighed by the cost and hassle involved".

Which was sort of my point--the 20mm was not a hands-down better
weapon than the .50 cal.

It was by war's end, but certainly not by enough to justify a retrofit
program.

And what great advances in the 20mm "by wars end" made it a hands-down
better weapon? Why was the F-86 so succesful when armed with MG's?


Cannon blow up more targets than ball ammo.

Come on, now. The amount of HE in the 20mm round of the day was not
that large,

Compared to how much in .50 ball?

When you consider the velocity and mass of the what, five or so .50
cal rounds that are hitting the target for every one old straight neck
20mm round?


and there are plenty of gun camera images of trucks,
trains, planes, etc., being blown to smithereens by .50 cal fires to
put that claim of yours to rest.

If I shoot you in the head with a .38 Special, you'll probably die. If I
shoot you in the head with a 120mm APFSDS round, you'll probably die.

Therefore .38 Special is just as good as 120mm.

Bad logic. A .38 can't kill a MBT. OTOH, .50 cals did kill everything
up to and including substantial warships (of the corvette size, IIRC),
and yes, they killed tanks as well (maybe not the Panther or Tiger,
but then again your 20mm would have been equally ineffective there as
well).



You keep leaping to the assumption that "an alternative might have been
better" means that "the existing weapon wasn't adequately lethal".

No, I am "leaping to the conclusion" that you cannot support your
earlier assertion that the 20mm was a hands-down better weapon for
strafing. Persoanally, I see advantages for both weapons, and figure
that they probably were around equally effective in the strafing role.
The effectiveness of the P-47 and MG-armed Corsair, the F6F, etc.,
prove that the .50 cal was a very effective weapon for strafe
missions; I have seen nothing that shows definitively that the
heavier, lower velocity, lower rate of fire, and more jam-prone 20mm
weapons of the day were demonstrably superior to them.


Of course, gun-camera film showing enemy vehicles motoring on through
the storm of tracers apparently undamaged doesn't get publicised much,
whoever was firing and whatever the calibre. (Try finding footage of LGB
misses, for instance)

Or can you show where the RAF
strafers were somehow more effective with their 20mm's than the USAAF
folks were?

I can point to the US Navy's decision sometime in 1943 or 1944 to
require new aircraft to be armed with cannon rather than guns, and to
the extinction of the .50 post-Korea (replaced, in aircraft like the
F-100 by... guess what, four 20mm cannon!)

Gee, are you gonna tell all those F6F pilots around during August 45
that their aircraft were underarmed? What about the MG armed Corsairs
of Korea? And that those MG armed F-86's racked up a much higher kill
ratio against those (I guess) superior armed Mig-15's? As another
poster has pointed out, the USAF went to the 20mm in-mass when the
later M39 became available--early efforts with the 20mm in that poor,
underarmed F-86F were unsuccessful.


To be really sarcastic, why is the A-10 built around a 30mm Gatling when
(by this tally) a noseful of .50s should be so lethal and effective?

Paul, you are truly stretching here. What does this have to do with
your complete inability to provide definitive proof that the .50 cal
was deficient in comparison to the 20mm's of the day in the ground
attack role? Can you show us where the Typhoon was so radically more
lethal than the P-47? No, you can't--which takes me back to my
original postion that you can not pronounce the 20mm of WWII a
hands-down better weapon than the .50 cal MG in the strafe attack.


The USN put 20mm rather than .50 in the Helldiver, and in later marks of
Corsair, and in the Bearcat and Tigercat. By Korea the Navy jets were
standardised on quadruple 20mm guns (F9F is the main example)

The Corsair of Korea fame was still toting the .50 cals, IIRC.

Mostly because the switch came late in the production run, and there was
no impetus to retrofit the gun-armed aircraft.

As were
the F6F's throughout WWII.

The F6F first flew in 1942 meaning the specifications were written too
early for direct lessons-learned, and certainly too early to be
influenced by (for example) the need to get rapid catastrophic kills on
Kamikazes.


I'll give you the Bearcat and Panther--but
the Corsair with MG's was probably conducting as many ground attack
runs in Korea as were those F9F's.

Was that a deliberate choice, or the USN using what it had?

Who cares? The fact is that the .50 cal was still being used in great
numbers by the USN years after you indicated the USN gave up on it
because it was not up to their needs.


And how about the USAAF during
WWII, with 20mm in the P-38 and some P-39's, and 37mm in other P-39's?

The 37mm seems to have been a very mixed bag (as it later was on the
MiG-15) - lethal if it hit, but too slow-firirng and lacking in velocity
to be likely to hit agile targets.

The 20mm was a good piece of kit, and seems to have succeeded well
enough to be retained on the P-38 (weren't early versions armed with
37mm?). Similarly, later Cobras went to 20mm rather than 37mm.

There are advantages to having a one-calibre battery: an example would
be the 2x50" + 1x20mm tail guns of some B-29s. Interestingly, the USAF
went to 20mm for defensive guns on the B-36 and later bombers; then back
to 4 x 50" for the B-52, until the -H model reverted to a 20mm Vulcan.

Confusing, huh?

The Navy switched wholesale to the 20mm late in WW2,

No, it did not.

Yes, they did, for all new designs and production. The results of that
decision mostly just missed the war.

The decision to change armament leads aircraft in combat by eighteen
months to two years. Which new USN fighter design from 1944 or 1945 used
machineguns rather than cannon?

Not during WWII it did not. Look at the original Corsair armament, and
how quickly that was upgraded to the six-.50 cal arrangement. Or the
B-17E/F/G gestation period.

The F4U night fighter variant did, IIRC, use the .50 MG's. And all of
the serving fighters which continued into production throught the end
of the war continued to retain the .50 cal, with the exception of some
400 copies of the -4 Corsair series.


The USAF stuck with the .50 well into
Korea, and then lurched towards the Mighty Mouse rocket rather than guns
for a while before switching back to the 4x20mm battery with the F-100.

Nope. The F-86 (E or F, can't recall which) was used in Korea with a
20mm armament, but did not pan out well (caused some compressor
stalls).

Not surprising - the Hunter and Swift both had major problems with gun
firings choking the engine.

http://home.att.net/~jbaugher1/p86_25.html

is interesting - sounds like they got the problems fixed pretty well.
They then put the de-bugged 20mm gun package into the F-86H, for ground
attack use... suggesting that it was considered more effective in that
role.

More than just debugged, I believe--they deleted part of the original
load, and I am not sure that the 20mm guns in the H were even the same
model as those tried out in the E/F trial. And yes, they were starting
to look at improving the hitting power--the newer cannon being more
reliable than the older 20mm's, and with the threat changing as
well--none of which has anything to do with the fact that the .50 cal
in the CAS/BAI role during WWII was not demonstrably less effective
than the 20mm.


I'm willing to be corrected, but I recall that the most-produced Sabre
was the D-model, gunless and armed with 24 x 2.75" rockets, and the
cannon-armed Sabres were mostly if not all foreign.

the USAF did introduce a cannon armed version, the H model (or
at least nearly 400 of them were armed with a more modest four cannon
fit), which had a long service record

About 5% of production, compared to 15% of Corsairs built with cannon?
Do I hear moving goalposts?

No. You hear a statement of fact--the latter US production run did
bring the 20mm into service, contrary to your claim that "mostly if
not all" cannon armed Sabres were foreign. The MG armed Sabres were
rplaced in active service by the F-100 and F-86H, with both later
replacing the earlier F-86's in the ANG in good time (not sure what
the history of the ANG F-86 early models was--did they have the .50
cals removed and replaced by 20mm?).


Not sure
on all the numbers, but my resource tells me that production of the
Sabre in all its guises totaled some 8500, and of that only about 2500
D's were built (and the later L's were all rebuilt D's, so take that
mod out of the running). I'd wager that the F model may have had a
larger run, being as it was the definitive Korean War model.

Doesn't seem to have managed it - I'm pretty sure the Sabre D was the
most-produced model. (Not the same as 'majority of those produced')

I stand corrected; the F production was only 1800 or so.

Brooks

"Keith Willshaw" wrote in message ...
"Kevin Brooks" wrote in message
om...


From a purely pragmatic point of view sticking with an established
gun design and logistics chain probably made sense but the reality
is that the 20mm cannon has superior penetration as it simply
has more KE and a larger explosive filling.

I say again, show me where the P-47 was ineffective with its .50 cals.
Or show me where the Typhoon was decidedly better (in which case I
wonder why the RAF was a P-47 user...).


Show me where I claimed it was ineffective ?

Are you defending Paul's assertion that the 20mm was a hands-down
better weapon in the strafe roll or not? I am just claiming rough
parity between the two weapons; if you are gonna claim one was
demonstrably better than the other, bring out the evidence.


The point is that the 20mm was MORE effective not that the .50
was useless , it clearly wasnt

Can you prove it was MORE effective? How so? You discount reliability,
rate of fire, ammo load, and velocity and reach that conclusion...how?



than the 20mm (and the USN agreed, as we saw with the armament that
was affiixed to the Hellcats and Corsairs through the end of the war,
and in the case of the Corsair through the Korean experience).


In point of fact the Corsair switched to cannon armament in
the F4U-4B and F4U-4C.

"Production included 2050 F4U-4s with six .50 guns, 297 F4U-4Bs or
F4U-4Cs with four 20mm cannon"


As I said

But I believe the .50 cals were still being produced upo to the very
end of the war?


Source: http://www.csd.uwo.ca/~pettypi/elevo...other/f4u.html

Come on, 15% of the aircraft manufactured were all that got the 20mm's
out of the -4 series.


The last 15%

Sure of that?



The AU-1 produced specifically for the marines during the Korean war
also had an all cannon armament

An even poorer example; only about 100 were produced during the war.
How many hundreds of older Corsairs were still flying with the .50 cal
during Korea? A photo from Vought's archive shows one with its six
MG's (see http://www.voughtaircraft.com/photos/data/planes8.htm).


The last Corsairs produced

And those poor deficiently armed older Corsairs were still slogging
along as well.





The USN switched to 20mm. the USAF didn't. Difference between
Pacific
and Europe, perhaps?

When did the USN switch to the 20mm during WWII, or for that
matter
during the Korean War? AFAIK, the standard remained the .50 cal in
both services until after the Korean conflict, when both began
shifting to the 20mm at roughly the same time (in the same general
timeframe that the A-1 was coming into major service with its
20mm,
the later F-86 variants were also gaining the heavier weapons,
IIRC,
as was the new F-100).

Brooks

The USN jets produced in the immediate post war period
were cannon armed. The Grumman F9F for example reached
the fleet in 1949 and had 4 20mm cannon as did the F2H
Banshee

The F9F-5 was indeed cannon armed. But, the USAF also had early
experience in cannon armament for fighters, roughly in the same
timeframe as what you describe. The P-38 offered a combined MG and
20mm cannon armament during WWII; the P-39 also sported cannon in both
the 20mm and 37mm guises. Likewise, the F-86 first sported 20mm during
the Korean conflict (though the initial experience was less than
satisfactory--it was not until the H model came along that the 20mm
appeared as the standard armament). The fact is that the USN did not
switch to 20mm during WWII, ahead of the USAAF, as Paul stated with
his "difference between the Pacific and Euro theaters" comment.

Brooks


Clearly it did since every fighter built after 1946 for the
USN was cannon armed.

Since when was 1946 "during WWII"??? Of the F4U-4 series. 85% were
produced with MG's; 100% of the F6F series was also MG armed. Vought
has a photo of a MG armed Corsair readying for takeoff in Korea. So
where in heck do you come up with the USN switching to the 20mm during
WWII?


Where did I claim this happened during WW2 ?

My words: "The fact is that the USN did not switch to 20mm during
WWII, ahead of the USAAF, as Paul stated with his "difference between
the Pacific and Euro theaters" comment."

Your response:

"Clearly it did since every fighter built after 1946 for the
USN was cannon armed."

That "clearly it did" refers to the "the USN did not switch to 20mm
during WWII...", right?


My words were 'after 1946' I believe

Show me where the 20mm strafer of WWII was more effective than the .50
cal strafer.

Brooks


Keith

"Kevin Brooks" wrote in message
om...
"Keith Willshaw" wrote in message
...
"Kevin Brooks" wrote in message
om...


From a purely pragmatic point of view sticking with an established
gun design and logistics chain probably made sense but the reality
is that the 20mm cannon has superior penetration as it simply
has more KE and a larger explosive filling.

I say again, show me where the P-47 was ineffective with its .50 cals.
Or show me where the Typhoon was decidedly better (in which case I
wonder why the RAF was a P-47 user...).


Show me where I claimed it was ineffective ?

Are you defending Paul's assertion that the 20mm was a hands-down
better weapon in the strafe roll or not? I am just claiming rough
parity between the two weapons; if you are gonna claim one was
demonstrably better than the other, bring out the evidence.


The fact that the USAF and USN did in fact both switch from
the .50 cal to the 20mm cannon would seem evidence enough


The point is that the 20mm was MORE effective not that the .50
was useless , it clearly wasnt

Can you prove it was MORE effective? How so? You discount reliability,
rate of fire, ammo load, and velocity and reach that conclusion...how?


Who says I discount those issues , presumably the USN and
USAF also considered them or they wouldnt have switched



than the 20mm (and the USN agreed, as we saw with the armament
that
was affiixed to the Hellcats and Corsairs through the end of the
war,
and in the case of the Corsair through the Korean experience).


In point of fact the Corsair switched to cannon armament in
the F4U-4B and F4U-4C.

"Production included 2050 F4U-4s with six .50 guns, 297 F4U-4Bs or
F4U-4Cs with four 20mm cannon"


As I said

But I believe the .50 cals were still being produced upo to the very
end of the war?


Quite so, mostly for the USAAF


Source: http://www.csd.uwo.ca/~pettypi/elevo...other/f4u.html

Come on, 15% of the aircraft manufactured were all that got the 20mm's
out of the -4 series.


The last 15%

Sure of that?



The AU-1 produced specifically for the marines during the Korean war
also had an all cannon armament

An even poorer example; only about 100 were produced during the war.
How many hundreds of older Corsairs were still flying with the .50 cal
during Korea? A photo from Vought's archive shows one with its six
MG's (see http://www.voughtaircraft.com/photos/data/planes8.htm).


The last Corsairs produced

And those poor deficiently armed older Corsairs were still slogging
along as well.


Well they were hardly going to leave them behind when there
was a war on were they ?

snip


Where did I claim this happened during WW2 ?

My words: "The fact is that the USN did not switch to 20mm during
WWII, ahead of the USAAF, as Paul stated with his "difference between
the Pacific and Euro theaters" comment."

Your response:

"Clearly it did since every fighter built after 1946 for the
USN was cannon armed."

That "clearly it did" refers to the "the USN did not switch to 20mm
during WWII...", right?


NO that clearly it did refers to the fact that almost every
USN aircraft manufactured from 1946 onwards used
cannon while the USAF continued building aircraft
armed with machine guns. Thus showing indisputably
that the USN did in fact switch to a strategy of using
cannon armed aircraft before the USAF.

That switch was clearly planned while the war was still
being waged, it does take a while to tool up production
when all is said and done.


My words were 'after 1946' I believe

Show me where the 20mm strafer of WWII was more effective than the .50
cal strafer.


Tony Williams & Emmanuel Gustin have a nice web page that
examines that very issue, they consider energy transferred
to the target , gun weight and rate of fire

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Keith

"Keith Willshaw" wrote in message ...
"Kevin Brooks" wrote in message
om...
"Keith Willshaw" wrote in message
...
"Kevin Brooks" wrote in message
om...


From a purely pragmatic point of view sticking with an established
gun design and logistics chain probably made sense but the reality
is that the 20mm cannon has superior penetration as it simply
has more KE and a larger explosive filling.

I say again, show me where the P-47 was ineffective with its .50 cals.
Or show me where the Typhoon was decidedly better (in which case I
wonder why the RAF was a P-47 user...).


Show me where I claimed it was ineffective ?

Are you defending Paul's assertion that the 20mm was a hands-down
better weapon in the strafe roll or not? I am just claiming rough
parity between the two weapons; if you are gonna claim one was
demonstrably better than the other, bring out the evidence.


The fact that the USAF and USN did in fact both switch from
the .50 cal to the 20mm cannon would seem evidence enough

Not really. They both found the .50 cal to be a good weapon throughout
the war; the USAF continued to use it until the "next generation" of
cannons became available, so to speak. Times changed, the threats
changed, capabilities changed--and the 20mm became the caliber of
choice. Again, if you are going to claim that the .50 cal was
demonstrably inferior to the 20mm during WWII, show some evidence--the
fact that both the USAF and USN continued to use .50 cal armament
throughout the Korean conflict would seem to contradict your theory.



The point is that the 20mm was MORE effective not that the .50
was useless , it clearly wasnt

Can you prove it was MORE effective? How so? You discount reliability,
rate of fire, ammo load, and velocity and reach that conclusion...how?


Who says I discount those issues , presumably the USN and
USAF also considered them or they wouldnt have switched

Read the response above.




than the 20mm (and the USN agreed, as we saw with the armament
that
was affiixed to the Hellcats and Corsairs through the end of the
war,
and in the case of the Corsair through the Korean experience).


In point of fact the Corsair switched to cannon armament in
the F4U-4B and F4U-4C.

"Production included 2050 F4U-4s with six .50 guns, 297 F4U-4Bs or
F4U-4Cs with four 20mm cannon"


As I said

But I believe the .50 cals were still being produced upo to the very
end of the war?


Quite so, mostly for the USAAF

Production of the MG armed F6F continued through November 45. I
believe -4 series Corsairs with MG armament were also still being
delivered when VJ Day came around. And you think this indicates the
..50 cal was demonstrably inferior?



Source: http://www.csd.uwo.ca/~pettypi/elevo...other/f4u.html

Come on, 15% of the aircraft manufactured were all that got the 20mm's
out of the -4 series.


The last 15%

Sure of that?



The AU-1 produced specifically for the marines during the Korean war
also had an all cannon armament

An even poorer example; only about 100 were produced during the war.
How many hundreds of older Corsairs were still flying with the .50 cal
during Korea? A photo from Vought's archive shows one with its six
MG's (see http://www.voughtaircraft.com/photos/data/planes8.htm).


The last Corsairs produced

And those poor deficiently armed older Corsairs were still slogging
along as well.


Well they were hardly going to leave them behind when there
was a war on were they?

Especially since, contrary to your indications, the USN did indeed
continue to procure MG armed fighters after the war was over (for
another three months, at least). And BTW, that F8F Bearcat? Well over
half of the Bearcat's produced (and production did not *start* until
Feb 45) were armed with...you guessed it, the ubiquitous .50 cal
MG's...



snip


Where did I claim this happened during WW2 ?

My words: "The fact is that the USN did not switch to 20mm during
WWII, ahead of the USAAF, as Paul stated with his "difference between
the Pacific and Euro theaters" comment."

Your response:

"Clearly it did since every fighter built after 1946 for the
USN was cannon armed."

That "clearly it did" refers to the "the USN did not switch to 20mm
during WWII...", right?


NO that clearly it did refers to the fact that almost every
USN aircraft manufactured from 1946 onwards used
cannon while the USAF continued building aircraft
armed with machine guns.

I thought you said the USAF also found the .50 cal inferior?

Thus showing indisputably
that the USN did in fact switch to a strategy of using
cannon armed aircraft before the USAF.

I'll buy that; I was incorrect in stating that both services switched
at the same general time.


That switch was clearly planned while the war was still
being waged, it does take a while to tool up production
when all is said and done.

I'd agree they started down that route before the war ended; but they
sure as heck did not, as another poster indicated, go "wholesale" to
the 20mm over the .50 cal, as the fact that they maintained production
of the MG armed F6F until after hostilities, along with the initial MG
armed F8F. The USN did not wake up one morning and say, "Gosh! We
gotta have 20mm's in our fighters because they are soooo much better
than the .50 cal!" If they found the .50 cal to be so puny in
comparison, one has to wonder why they did not plan rearming the F6F's
and go with an initial 20mm loadout for the F8F, which only entered
series production in the last six months of the war.




My words were 'after 1946' I believe

Show me where the 20mm strafer of WWII was more effective than the .50
cal strafer.


Tony Williams & Emmanuel Gustin have a nice web page that
examines that very issue, they consider energy transferred
to the target , gun weight and rate of fire

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Do they say that the .50 cal armed P-47 was inferior to the 20mm armed
Typhoon?

Brooks


Keith

In message , Kevin
Brooks writes
"Paul J. Adam" wrote in message
First flight in August 1942.

And standard carrier borne fighter throughout the latter part of the
war, when you are claiming the USN went "wholesale" to the 20mm?

When you change your procurement policy, it doesn't magically alter the
existing lines, nor those aircraft already in service.

First flight August 1944.

Wow. And that first aircraft was armed with.....50 cal MG's, right?

Same as the first Typhoon was armed with .303" MGs.

In both cases, it was considered worthwhile to expend effort, time and
money changing the design to an all-cannon armament.

The F4U-1C served in WW2 and the F4U-5 in Korea with a 20mm armament.

Look at the numbers; more .50 cal armed Corsairs served in both
conflicts.

That's because the change happened late, with a considerable production
already in place.

Remind me where I said their _use_ was wholesale?

Oh, pardon me. Just waht were you claiming as "wholesale"?

Adoption. Which USN fighter was procured with a machine-gun armament
after 1944?

I said that the USN switched its preferred armament from .50 to 20mm in
1944 or thereabouts, which is clearly reflected in subsequent design and
procurement decisions.

One wonders why .50 cal armed naval aircraft were still coming off the
lines at the end of the war?

Because the existing lines for older designs weren't modified.

The war ended before that decision filtered
through to the front line.

Gee, since they were still flying Corsairs with the .50 cal MG's in
Korea five and six years later, one wonders just how "wholesale" this
decision really was.

I wouldn't take Korea as a great example of logical procurement policy:
it was fought with what was available, not what was desired.

--
When you have to kill a man, it costs nothing to be polite.
W S Churchill

Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk

In message , Kevin
Brooks writes
"Paul J. Adam" wrote in message
...
Checking, that's true - on the other hand, you did a lot more damage
with the 20mm guns. I recall a vivid account from a Hurricane pilot
flying night intruder over France, describing his firing pass on a
German bomber in a Hurricane IIC; and his startled surprise at how the
aircraft caught fire and went out of control almost at once, compared to
the long 'squirt' needed with machine-gun fire.

Yeah, and the .303's in the Hurricane were not .50 cals, were they?

Nor were they 20mm.

I
believe one can also find plenty of examples of MG fire quickly
destroying both german and Japanese aircraft during WWII (i.e., all of
those large deflection snap shots).

And yet the USN felt a need to get 20mm into the Fleet, because it would
destroy Kamikazes more quickly and reliably.

I doubt it, or the RAF would have stuck with .303".

I do believe ammo volume was a concern for the USAAF; one has to
wonder if the 20mm was so invaluable, why did it get dumped from so
many aircraft? I belive a lot of P-38's dumped them, as did the B-29
in its tail armament (we went through this a while back--issue being
both weight *and* performance problems).

The B-29 often also dumped most of its turreted .50" guns other than the
tail pair - shall we assume that a shocking flaw was suddenly found with
the .50"?

The USN switched to 20mm guns for its new-production fighters and
dive-bombers (the dive-bombers arrived before the end of the war, the
fighters mostly didn't) but the USAF didn't.

Partly correct. The USN "sort of" switched, as best I can figure; they
produced MG armed fighters to the very end of the war, I believe (even
the vast majority of the -4 series of Corsairs were MG armed). The
20mm did not come into large scale USN/USMC fighter use until after
the war, and even then they retained MG armed aircraft like the
Corsair through the Korean conflict.

"Retained" because there wasn't much new production, rather than from
choice.

Burst effect is handy when strafing groups. It also ups lethality
against a lot of soft targets (using HEI) and harder targets like APCs
and self-propelled guns (using AP).

The 20mm of the day (not the same as todays more powerful charges,
both propellent and filler wise) was not the big hitter that you
apparently believe it was, IMO.

Not a "big hitter" but more powerful than .50".

Plenty of German vehicles, including
armored ones, were killed by the ol' .50 cal, too.

Plenty of German vehicles killed by .303" strafing, but that doesn't
make it a superior weapon. You keep waving this strawman that because
the 20mm was more lethal, I'm claiming that the 50" was somehow meant to
be ineffective, and that just isn't so.

Not in question. But would the P-47 have done better with four or six
20mm vice eight .50s? (or twelve .30s, for that matter?)

I doubt it would have really been any more effective with the cannon
armament.

Really? What's the basis for that analysis?

To take a different example, the US Army replaced the M-1 with the M-14.
Does that mean the M-1 was a flawed, ineffective weapon and a dangerous
liability to the troops carrying it? Don't think so, somehow.

Careful. By that approach, we went to the 5.56mm over the 7.62mm
because volume of fire became more important than hitting power--what
does that say about the .50 cal vs 20mm argument?

Given that a reason why the USAF abandoned the .50" was because it
visibly lacked lethality against the MiG-15 (many kills, but also many
recorded cases of 'lost kills' where MiGs were hit and still escaped) it
says quite a lot.

What's the relative numbers of A-36s and P-47s in USAAF service, and a
sortie count for each?

Hey, no argument that the P-47 was the better CAS/BAI platform--but
the P-51/A-36 was indeed used for ground attack during WWII, and in an
amount that IMO exceeds the "wasn't much used" that you have
attributed to it.

What's the relative sortie count?

What _is_ interesting is that the F-51 was forced into the role for
Korea, where the P-47 would definitely have been better suited to the
role.

Driven by the fact that they had F-51s available to reactivate rather
than a superiority for the mission.

Who cares what drove it--

I do.

it was used in that role.

And does that indicate that it was the best option possible for that
role? Or does it indicate that it was all that was available?

This is why the reasons are important.

It was by war's end, but certainly not by enough to justify a retrofit
program.

And what great advances in the 20mm "by wars end" made it a hands-down
better weapon?

Comparable rate of fire, considerably more destructive projectile.

Why was the F-86 so succesful when armed with MG's?

How many kills did it lose because the MGs weren't able to reliably kill
MiGs? Flicking through Jackson's "Air War over Korea" reveals as many
MiGs 'damaged' as confirmed killed by Sabres, because while the F-86
could get into firing position, and the .50" battery was accurate and
would get hits, it took an average of a thousand rounds of .50" to down
a MiG (which meant a Sabre carried only two stored kills on that
average).

Compared to how much in .50 ball?

When you consider the velocity and mass of the what, five or so .50
cal rounds that are hitting the target for every one old straight neck
20mm round?

Nope. Typical installation would be six .50" guns firing at ~750rpm, so
a one-second burst looses off 75 rounds of .50 ball. Compare that to
four Hispano V, also firing 750rpm - you're looking at sixty rounds of
mixed HE and AP, or seventy-five rounds of ball.

(The faster-firing M3 .50" was a post-war innovation, confined to the
USAF - that would get you 120 rounds in a one-second burst from six
guns, but they're still only ball rounds)

You keep leaping to the assumption that "an alternative might have been
better" means that "the existing weapon wasn't adequately lethal".

No, I am "leaping to the conclusion" that you cannot support your
earlier assertion that the 20mm was a hands-down better weapon for
strafing.

So, why is the A-10 armed with a 30mm cannon instead of a battery of
..50" guns? For that matter, why were the A-1, A-4, and A-7 all
cannon-armed rather than using machine-guns?

Persoanally, I see advantages for both weapons, and figure
that they probably were around equally effective in the strafing role.
The effectiveness of the P-47 and MG-armed Corsair, the F6F, etc.,
prove that the .50 cal was a very effective weapon for strafe
missions;

It proves nothing about how those missions might have gone, had they
been armed with something different.

I have seen nothing that shows definitively that the
heavier, lower velocity, lower rate of fire, and more jam-prone 20mm
weapons of the day were demonstrably superior to them.

Rate of fire? Nope, the Hispano V fired just as fast as the M2 Browning
(750rpm each)

Reliability? Many aircraft had problems with their gun installation
(including the P-51), typically with jamming caused by wing flex
distorting gun mounts or ammo feeds. Not a gun issue, a mounting issue.

Low muzzle velocity? 880m/s for a .50, 850m/s for a Hispano V (which had
a shortened barrel - 880m/s was typical for longer 20mm).

Heavier? 29kg for the .50" gun, 42kg for the Hispano - so six M2s end up
heavier than four Hispanos.


I can point to the US Navy's decision sometime in 1943 or 1944 to
require new aircraft to be armed with cannon rather than guns, and to
the extinction of the .50 post-Korea (replaced, in aircraft like the
F-100 by... guess what, four 20mm cannon!)

Gee, are you gonna tell all those F6F pilots around during August 45
that their aircraft were underarmed?

By war's end, yes. "Underarmed" is a relative term, of course: they had
an effective battery, but it was possible to do better.

What about the MG armed Corsairs
of Korea?

Likewise. The Corsairs weren't the aircraft of choice for Korea, they
were used because they were available.

And that those MG armed F-86's racked up a much higher kill
ratio against those (I guess) superior armed Mig-15's?

And yet the Sabre's MGs proved lacking in lethality... allowing many
MiGs to limp away, and driving a shift to heavier calibres.

As another
poster has pointed out, the USAF went to the 20mm in-mass when the
later M39 became available--early efforts with the 20mm in that poor,
underarmed F-86F were unsuccessful.

Due to gun gas ingestion, rather than any flaws in the weapon. (Similar
problems plagued the RAF's Hunter and Swift development - the 30mm ADEN
worked just fine, it was persuading the engine not to guzzle the muzzle
blast and stall that was a problem)

To be really sarcastic, why is the A-10 built around a 30mm Gatling when
(by this tally) a noseful of .50s should be so lethal and effective?

Paul, you are truly stretching here.

No, I'm asking why a unique, heavy and expensive weapon was chosen for
ground-attack in favour of a cheaper, lighter alternative.

What does this have to do with
your complete inability to provide definitive proof that the .50 cal
was deficient in comparison to the 20mm's of the day in the ground
attack role?

I'm giving you the data, you're ignoring it and insisting that I'm
"claiming it was deficient". It was at least adequate: it's just that
there were alternatives that were even better.

Can you show us where the Typhoon was so radically more
lethal than the P-47?

Neither used their guns as their primary air-to-ground armament, and
there was no radical difference in lethality between US and UK bombs and
rockets.

Was that a deliberate choice, or the USN using what it had?

Who cares?

It's significant because it drives the results.

The fact is that the .50 cal was still being used in great
numbers by the USN years after you indicated the USN gave up on it
because it was not up to their needs.

The USN didn't "give up on it", they elected to procure new aircraft
armed with 20mm rather than .50. That decision was affected by the end
of the war, the procurement slowdown, and the Korean malaise that
strength couldn't be diverted from Europe and so Korea was fought with
reserve stocks (the saga of F-84 deployment is a good example)

Yes, they did, for all new designs and production. The results of that
decision mostly just missed the war.

The decision to change armament leads aircraft in combat by eighteen
months to two years. Which new USN fighter design from 1944 or 1945 used
machineguns rather than cannon?

Not during WWII it did not.

Look at the F8F Bearcat: first flight in 1944, just missed combat
service in 1945. About eighteen months.

Or the
B-17E/F/G gestation period.

How about the B-29 gestation? Or the F-80? By war's end, it was taking
longer to get aircraft from concept to service.

The F4U night fighter variant did, IIRC, use the .50 MG's.

Was it new-build or a conversion?

And all of
the serving fighters which continued into production throught the end
of the war continued to retain the .50 cal, with the exception of some
400 copies of the -4 Corsair series.

"Retained" is not the same as "new designs armed with", of course.

Not surprising - the Hunter and Swift both had major problems with gun
firings choking the engine.

http://home.att.net/~jbaugher1/p86_25.html

is interesting - sounds like they got the problems fixed pretty well.
They then put the de-bugged 20mm gun package into the F-86H, for ground
attack use... suggesting that it was considered more effective in that
role.

More than just debugged, I believe--they deleted part of the original
load, and I am not sure that the 20mm guns in the H were even the same
model as those tried out in the E/F trial. And yes, they were starting
to look at improving the hitting power--the newer cannon being more
reliable than the older 20mm's, and with the threat changing as
well--none of which has anything to do with the fact that the .50 cal
in the CAS/BAI role during WWII was not demonstrably less effective
than the 20mm.

Basic OA indicates that it most definitely was. Same problems applied to
the AC-130's armament evolution, which started out with 4 x 7.62mm and 4
x 20mm guns, and rapidly jettisionned the 7.62mm and some 20s to add
40mm guns. Provided you could get hits, explosive shell was a lot more
lethal than ball.

About 5% of production, compared to 15% of Corsairs built with cannon?
Do I hear moving goalposts?

No. You hear a statement of fact--the latter US production run did
bring the 20mm into service, contrary to your claim that "mostly if
not all" cannon armed Sabres were foreign.

I'd call 95% "most" - what would your definition be, considering that
elsewhere 15% is "a small minority"?

The MG armed Sabres were
rplaced in active service by the F-100 and F-86H, with both later
replacing the earlier F-86's in the ANG in good time (not sure what
the history of the ANG F-86 early models was--did they have the .50
cals removed and replaced by 20mm?).

At that point, I'd guess the aircraft were left as-is until replaced.

--
When you have to kill a man, it costs nothing to be polite.
W S Churchill

Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk

"Kevin Brooks" wrote in message
om...
"Keith Willshaw" wrote in message
...
"Kevin Brooks" wrote in message
om...
"Keith Willshaw" wrote in message
...
"Kevin Brooks" wrote in message
om...


From a purely pragmatic point of view sticking with an
established
gun design and logistics chain probably made sense but the
reality
is that the 20mm cannon has superior penetration as it simply
has more KE and a larger explosive filling.

I say again, show me where the P-47 was ineffective with its .50
cals.
Or show me where the Typhoon was decidedly better (in which case I
wonder why the RAF was a P-47 user...).


Show me where I claimed it was ineffective ?

Are you defending Paul's assertion that the 20mm was a hands-down
better weapon in the strafe roll or not? I am just claiming rough
parity between the two weapons; if you are gonna claim one was
demonstrably better than the other, bring out the evidence.


The fact that the USAF and USN did in fact both switch from
the .50 cal to the 20mm cannon would seem evidence enough

Not really. They both found the .50 cal to be a good weapon throughout
the war; the USAF continued to use it until the "next generation" of
cannons became available, so to speak. Times changed, the threats
changed, capabilities changed--and the 20mm became the caliber of
choice. Again, if you are going to claim that the .50 cal was
demonstrably inferior to the 20mm during WWII, show some evidence--the
fact that both the USAF and USN continued to use .50 cal armament
throughout the Korean conflict would seem to contradict your theory.


The Korean war caught the US flatfooted, they had to use whatever
was available. The USAF used the P-51 in the ground attack
role because in the early part of the war its all they had.

The USAF also found to its chagrin that their sabre pilots
were having considerable difficulty inflicting lethal damage
on Mig-15's with .50 cal MG's



The point is that the 20mm was MORE effective not that the .50
was useless , it clearly wasnt

Can you prove it was MORE effective? How so? You discount reliability,
rate of fire, ammo load, and velocity and reach that conclusion...how?


Who says I discount those issues , presumably the USN and
USAF also considered them or they wouldnt have switched

Read the response above.




than the 20mm (and the USN agreed, as we saw with the armament
that
was affiixed to the Hellcats and Corsairs through the end of
the
war,
and in the case of the Corsair through the Korean experience).


In point of fact the Corsair switched to cannon armament in
the F4U-4B and F4U-4C.

"Production included 2050 F4U-4s with six .50 guns, 297 F4U-4Bs or
F4U-4Cs with four 20mm cannon"


As I said

But I believe the .50 cals were still being produced upo to the very
end of the war?


Quite so, mostly for the USAAF

Production of the MG armed F6F continued through November 45. I
believe -4 series Corsairs with MG armament were also still being
delivered when VJ Day came around. And you think this indicates the
.50 cal was demonstrably inferior?


The F4U from the 4C series onwards was fitted with cannon.
The first 300 of the production F4U-4Cs were assigned to Marine Air
Group 31 and were taken into the Battle for Okinawa aboard the escort
carriers Sitko Bay and Bereton.

Keith

Comments:
1) The MiG15 had a centrifugal comprerssor engine which is
considerably more resistant to battle damage tan an axial flow. Sveral
T33 (Allison J33 centrifugal engine) tow planes at Nellis took 50 cal
hits from clueless students getting sucked into deep six and still
firing at the banner tow target. This PO'd the tow pilot who would
jettison the banner into the shooter's face. But the T33 somehow
always got back home albeit with holes in the turbine disc. (Only two
guns were loaded in the 86s, and the students were poor shots.)
2) At high altitude hits in fuel tanks with 50 cal API did not result
in fires as would occur at lower altitudes.
3) Note that 50 cal API is considerably more effective than ball -
each strike results in a ball of fire about a foot in diameter. (Main
value in air to air for the shooter is that you can tell you're
getting hits).
4) Some of the 20m cannon were not very reliable - including the one
in the AD and the one in the F8. (OTH the M61 - although a different
breed of cat - is very reliable.)
5) The A10 was designed about a tank-killing gun - so the 50 vs 20
argument is not germane at all.

Walt BJ

(Corey C. Jordan) wrote in message .. .
On Wed, 13 Aug 2003 20:24:02 +0100, "Paul J. Adam"
wrote:

The USN put 20mm rather than .50 in the Helldiver, and in later marks of
Corsair, and in the Bearcat and Tigercat. By Korea the Navy jets were
standardised on quadruple 20mm guns (F9F is the main example)

Not to mention a considerable number of F6F-5N Hellcats were in service
with two 20mm cannon and four .50 caliber MGs as early as 1944.

F7F-2N Tigercats were armed with quad 20mm. They were in theater just prior to
Japan's surrender.

The USN wanted all night fighters fitted with 20mm cannon.

For the reasons why the 20mm was considered to be much more effective
than the .50", see: http://www.quarry.nildram.co.uk/WW2guneffect.htm

For the reasons why the USA made relatively little use of the 20mm
despite its considerable advantages, see:
http://www.quarry.nildram.co.uk/US404.htm

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/