AHC: P-51 Mustang even more prominent

How about maneuverability and range?

Also not quite clear on what you mean here.
Edit:
looking at the report the 2 cannon 20mph loss was because the RPM and BHP was considerably less.

The range would be barely decreased, manuverability and RoC, especially with early V-1710 and above ~13000 ft would've been nothing to write home about. Ditto for the rate of roll.
I'd stick with 4 HMGs at least until 2-stage engine is installed, and then continue with either 6 HMGs or 2 cannons + 2 HMGs.
 
I believe the postings that note that P-51 was primarily used against Japanese and German fighters are correct. Apparently six .50s were quite sufficient for this. 20 mm would have probably been more useful for bombers. Fighter engagements are fleeting and a lot of rounds into target are critical. Russians apparently did like the engine mounted 20 mm for the YAK-3.
 

Deleted member 1487

I believe the postings that note that P-51 was primarily used against Japanese and German fighters are correct. Apparently six .50s were quite sufficient for this. 20 mm would have probably been more useful for bombers. Fighter engagements are fleeting and a lot of rounds into target are critical. Russians apparently did like the engine mounted 20 mm for the YAK-3.
Entirely correct. Though the P-51 ended up being used for a lot of ground strafing when German fighters were wiped out, where 20mm cannons would have been better. But unless you're using AP shells or firing at longer range, the heavy long cannons (80 caliber lengths for the HS.404!) was unnecessary for that, but helpful for aircraft engagement. Something like the German MG FF with 'minengeschoss' shell would have been great for ground strafing and half the weight and barrel length.
https://en.wikipedia.org/wiki/MG_FF_cannon
https://en.wikipedia.org/wiki/Hispano-Suiza_HS.404
 
Looking a bit at history of the Merlinized P-40, the P-40F - British sent the Merlin to Curtiss, that 1st flew on June 30th, 1941. Thus it is not a long shot that British do the same for the Mustang, so we can see Merlin Mustang taking off some time in mid 1941. Granted, it will be the 1-stage supercharged engine in the nose, but it will still outpace any historical service-worthy Allison Mustang (those were good for up to 390-410+ mph, depending on the engine), especially above 20000 ft. After that, it might be a good idea that second source kicks in - say, Merlin Mustangs are produced in Dallas, Allison Mustangs in Inglewood as historically, preferably with drop tank facility.
Time for other versions - Twin Mustang (say, Fisher produces it?), Mustang with R-2800 (Bearcat capability, but 2 years earlier)?
 

hipper

Banned
Not sure the wings were set up to handle the HS.404, certainly not within the wings that is. If they could it would only be 1 per wing, which then leaves them with only 2 cannons and less overall firepower.

The US navy thought 1 20mm equaled 3 50 caliber Mgs so it's a wrap
 

Deleted member 1487

The US navy thought 1 20mm equaled 3 50 caliber Mgs so it's a wrap
To achieve what? In terms of destructive potential, but in terms of rate of fire, density of fire, ability to score hits, etc?
 

Deleted member 1487

Shooting things down
Right, in that case every rifleman should carry a .50 caliber rifle, right? Connect with it and you with put down whatever you're shooting at.
The problem, as with aircraft, is all the other stuff, like weight of the gun, ammo, density of fire, impact of the performance of the aircraft speed of the round, etc. Just like with military trials for small arms, they found smaller rounds fired with faster follow shots and at a higher speed would be much more likely to get hits and result vs. fewer numbers of heavier bullets. It is probably right that the destructive impact of 1x 20mm round is worth 3 hits with a .50 caliber round on an aircraft, the issue is getting the connection to get results. Against bombers a 20mm cannon in the minimum to get any result and probably not even enough, but against a small, maneuvering fighter 3x .50 caliber shots results in more chances to connect than 1x 20mm shot. The minimum necessary caliber to get a result on a fighter is substantially less than a bomber due to size. The HS404 round is over 2.5x the weight of the Browning .50 caliber, meaning you get a lot more ammo with even 2x .50 caliber MGs than 1x 20mm cannon, plus the rounds fly faster and the gun shoots faster.
 
Shooting things down
Bombers or fighters?

A hit with a 20mm cannon is worth roughly 3 times as much as a hit with a heavy machine gun. But you won't get the same rate of fire and you won't have as many guns. If you are fighting bombers or multi engine fighters you need the cannons do kill stuff. Remember the navy often fights big planes and needs to kill them before they can drop their ordinance.

Lets compare 4 cannons with 6 heavy machine guns.

The gun weight is similar.

The heavy machine guns will have roughly twice the rate of fire and in all fairness get twice the amount of hits.roughly 4k rpm for 6hmg combined compared with 2k rpm for the cannons.

The cannons shells weigh roughly three times as much as a heavy machine gun round.

So the 4 cannons has roughly 1.5 times as much throw weight but will get half as many hits.

The American usaaf believed that in fighter vs fighter engagements the fighter with the minimum armanent to damage the enemy plane would protect a bomber stream sufficiently. They also believed that the heavy machine gun did that damage so it was sufficient.

In carrier defense it was commonly believed you needed to kill a bigger plane as it came in. Cannons were considered essential for that purpose. Also battle of Britain you had to face fighters but you also had to face bigger bombers so you needed the bigger guns. You also needed to face bigger fighters so the cannons were useful there too.

I'd be more interested in a mustang with 8 heavy machine guns if possible in its long range escort role than trying to put cannons on there. If it goes for another role you can of course reconsider the armament.
 
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Why is the US Browning 0.5" machine gun, referred to as 50 cal? I can well remember 0.5" MGs mounted on AFVs in the Gulf war being referred to as such - what happened in the press it got transposed into 50mm!!
So, please can we have 0.5" or point-fives, or even half-inch, rather than 50cal.
 
Why is the US Browning 0.5" machine gun, referred to as 50 cal? I can well remember 0.5" MGs mounted on AFVs in the Gulf war being referred to as such - what happened in the press it got transposed into 50mm!!
So, please can we have 0.5" or point-fives, or even half-inch, rather than 50cal.
Edited
 
Bombers or fighters?

A hit with a 20mm cannon is worth roughly 3 times as much as a hit with a heavy machine gun. But you won't get the same rate of fire and you won't have as many guns. If you are fighting bombers or multi engine fighters you need the cannons do kill stuff. Remember the navy often fights big planes and needs to kill them before they can drop their ordinance.

Lets compare 4 cannons with 6 heavy machine guns.

The gun weight is similar.

The heavy machine guns will have roughly twice the rate of fire and in all fairness get twice the amount of hits.roughly 4k rpm for 6hmg combined compared with 2k rpm for the cannons.

The cannons shells weigh roughly three times as much as a heavy machine gun round.

So the 4 cannons has roughly 1.5 times as much throw weight but will get half as many hits.

The throw weight comparison asumes that each gun fires soild shot, and that was not the case. Explosive content that is found in cannons shells was there with a purpose. USN indeed judged that single Hispano was worth 3 .50 Brownings for air combat, at least going with what Tony Williams said. And that is after the .50 got increase in the RoF from 600 to 800 rpm ( in 1940), and after Americans copied the Soviet 12.7mm projectile (by ~1943 in production).
With that said, a more prominent Mustang needs, IMO:
1. (or 2.) beter engine(s) sooner
2. (or 1.) greater number produced
3. more fuel carried

Switch to cannon armament is probably a priority #4 or maybe even #5, after the improvement of rate of roll.

The American usaaf believed that in fighter vs fighter engagements the fighter with the minimum armanent to damage the enemy plane would protect a bomber stream sufficiently. They also believed that the heavy machine gun did that damage so it was sufficient.

In carrier defense it was commonly believed you needed to kill a bigger plane as it came in. Cannons were considered essential for that purpose. Also battle of Britain you had to face fighters but you also had to face bigger bombers so you needed the bigger guns. You also needed to face bigger fighters so the cannons were useful there too.

I'd be more interested in a mustang with 8 heavy machine guns if possible in its long range escort role than trying to put cannons on there. If it goes for another role you can of course reconsider the armament.

8 HMGs will severely reduce the number or rounds per gun on the Mustang, that already carried much less rounds per gun than P-47 or P-38.
What USAF believed was probably driven by 'hmm, our Hispanos are not really that reliable as what British, Germans or Soviets produce, so let's stick to what actually works against enemy fighters'.
 
More prominent? "Mustang" tends to be the first thing that leaps to people's minds if you say "World War 2 American Fighter Plane". You don't get more prominent then that.
 
Easy, just have the design initially use the Packard Merlin and the rest is history. It's utility then goes up and when the need for a long range escort emerges, it is easier to make that redesign happen.
Well.... That requires there BE a Packard Merlin in the first place. Which was a direct result of the improved performance of the British Merlin experimental version of the P51.

And it took quite a little while for Packard to sort out the redesign and manufacturing of the British Merlins to US production. Things like screw threads are different, just for starters, and in the UK Merlins were far more hand-built than US engines were, so ...

If Britain sees that war is inevitable when Hitler moves into (the rest of) Czechoslovakia in March 1939, and a study shows that Merlin engines are going to be in desperate short supply, and so they start talking with Packard by, say June 1939,
Maybe have the engines be 'built' in the Windsor Ontario plant (see, e.g. http://packardinfo.com/xoops/html/uploads/newbb/177_4d0b7473ad2b4.jpg)

If I remember correctly, there was an abortive attempt to have Ford build the Merlin first, and they just couldn't do it.

So. Start earlier. Go straight to Packard. Maybe you could have a Packard Merlin ready in time for the first P-51 (NA-91)s.
 

Deleted member 1487

Well.... That requires there BE a Packard Merlin in the first place. Which was a direct result of the improved performance of the British Merlin experimental version of the P51.

And it took quite a little while for Packard to sort out the redesign and manufacturing of the British Merlins to US production. Things like screw threads are different, just for starters, and in the UK Merlins were far more hand-built than US engines were, so ...

If Britain sees that war is inevitable when Hitler moves into (the rest of) Czechoslovakia in March 1939, and a study shows that Merlin engines are going to be in desperate short supply, and so they start talking with Packard by, say June 1939,
Maybe have the engines be 'built' in the Windsor Ontario plant (see, e.g. http://packardinfo.com/xoops/html/uploads/newbb/177_4d0b7473ad2b4.jpg)

If I remember correctly, there was an abortive attempt to have Ford build the Merlin first, and they just couldn't do it.

So. Start earlier. Go straight to Packard. Maybe you could have a Packard Merlin ready in time for the first P-51 (NA-91)s.
Got my TLs mixed up, thought the Packard Merlin came in 1940 the first P-51 prototype in 1941, it was the other way around. So yeah, that makes things quite a bit harder, but you could theoretically see the Packard Merlin be put into the P-51 earlier as soon as they work out the kinks in US production. I like your idea about the Ontario plant.
 
Lets compare 4 cannons with 6 heavy machine guns.

The gun weight is similar.

The heavy machine guns will have roughly twice the rate of fire and in all fairness get twice the amount of hits.roughly 4k rpm for 6hmg combined compared with 2k rpm for the cannons.

The cannons shells weigh roughly three times as much as a heavy machine gun round.

So the 4 cannons has roughly 1.5 times as much throw weight but will get half as many hits.

I think it'd be more accurate to say that six Brownings would have about 50% more rounds per minute, as the RoF of the Hispano and the Browning were roughly equal. The Mk II Hispano fired at 650-700 rpm (though RAF groundcrews often tweaked the gun to fire faster - in some cases up to 1000 rpm), while the Mk V fired at 800-850 rpm. The problem with the Brownings is that the nature of the target is not constant. Most aircraft shot down in WWII were taken by surprise, so for the first 0.5-1.0 seconds the attacking pilot is firing at a target that's basically just pootling along, but as soon as the victim becomes aware of the attacker he will begin to throw his aircraft all over the sky, which will make him a much harder target. The important thing in combat is the amount of firepower delivered in that first second, and the Hispanos simply do that so much better. Thus a single Browning would need to fire much longer than three seconds to inflict damage equal to a one-second burst from a Hispano, even though (on paper) the cannon is only three times as effective as the machine-gun.
 
Something I've tossed up years ago:

mustangBearcat.JPG


I think it'd be more accurate to say that six Brownings would have about 50% more rounds per minute, as the RoF of the Hispano and the Browning were roughly equal. The Mk II Hispano fired at 650-700 rpm (though RAF groundcrews often tweaked the gun to fire faster - in some cases up to 1000 rpm), while the Mk V fired at 800-850 rpm.

The Hisso II fired at 600 rpm, and Mk.V at 750 rpm, at least when reading what Tony Williams says. The .50 BMG was at 600 rpm until some time of 1940, when the RoF was increased to 800 rpm; all figures for non-synchronysed installation. Belgians advertised their versions of the BMG doing 1000-1200 rpm, before the ww2 started.
Could you please toss some creditable sources on RAF groundcrews tweaking the Mk.II doing up to 1000 rpm?

The problem with the Brownings is that the nature of the target is not constant. Most aircraft shot down in WWII were taken by surprise, so for the first 0.5-1.0 seconds the attacking pilot is firing at a target that's basically just pootling along, but as soon as the victim becomes aware of the attacker he will begin to throw his aircraft all over the sky, which will make him a much harder target. The important thing in combat is the amount of firepower delivered in that first second, and the Hispanos simply do that so much better. Thus a single Browning would need to fire much longer than three seconds to inflict damage equal to a one-second burst from a Hispano, even though (on paper) the cannon is only three times as effective as the machine-gun.

Agree that most of, at least fighters, were taken down due to surprise. Thus even the low MV versions of the Oerlikon FF were racking some serious kills.
 
More prominent? "Mustang" tends to be the first thing that leaps to people's minds if you say "World War 2 American Fighter Plane". You don't get more prominent then that.

You can, if the US took more interest in it earlier - rather than a NIH attitude, while the concentrated their future fighter effort into the P-47 & P-38.
 
Something I've tossed up years ago:

View attachment 342747



The Hisso II fired at 600 rpm, and Mk.V at 750 rpm, at least when reading what Tony Williams says. The .50 BMG was at 600 rpm until some time of 1940, when the RoF was increased to 800 rpm; all figures for non-synchronysed installation. Belgians advertised their versions of the BMG doing 1000-1200 rpm, before the ww2 started.
Could you please toss some creditable sources on RAF groundcrews tweaking the Mk.II doing up to 1000 rpm?



Agree that most of, at least fighters, were taken down due to surprise. Thus even the low MV versions of the Oerlikon FF were racking some serious kills.

Oddly enough I saw the reference to Hispanos being tweaked on Tony Williams' forum, but when I try to find it the search only goes back 3 months.

The 'one-second' rule is why there was a constant drive to improve firepower by increasing RoF and shell-weight, resulting (in WWII) in the excellent MG213, which fired very heavy 20mm rounds at a very high RoF, and post-war in the Vulcan.
 
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