Build an improved Gloster F5/34

[tomo pauk]

We keep falling into the displacement trap. It is possible to compensate for small displacement with RPM at the fundamental stage (initial design/development).
Just for fun a few simple numbers on liters per minute.
Allison/3000rpm....................42,000l/m
H-S 12Y/2400rpm..................43,200l/m
Jumo 211/2500rpm..............43,750l/m
DB 601A/2400rpm................40,680l/m
DB 601E/2600rpm.................44,070l/m
DB 605 AM/2800rpm...........49,980l/m
Merlin/3000rpm.....................40,500/m

People will fall into the displacement trap if they botch up something, or we compare an old engine with the new engine - this is how Merlin was kept in the race. It is indeed sometimes possible to compensate for the deficit in displacement, especially with an up-to-date S/C, but in general the greater displacement, the greater power (assuming engines of the same generation).
Multiplying displacement with RPM is what I favor. ~27 x 3000= 81000 (Merlin), ~28 x 3000 = 84000 (V-1710) vs. ~34 x 2400 = 81600 (DB 601A), vs. ~34 x 2700 = 91800 (DB 601E) -> the small engines running at 3000 rpm better have the up-to date S/Cs to compensate, and V-1710 didn't have them.
~34 x 2600 = 88400 - DB 601N that was in service by Autumn of 1940.

The HS 12Y does show a pitfall. It was 36 liters which makes it the largest engine (displacement wise) in the list. It is also the tied for last place in rpm with the early DB 601 and it is, by the far, the lightest engine on this list. This meant it could not stand up to making high power without breaking.

Yes, a heavier engine will make better power.

It isn't. But if you are trying to compare climbs to 15,000 or 20,000ft and light plane X is getting to 20,000ft 2-4 minutes quicker than fatty plane Y when plane Y is using "standard" power then WEP can equalize things a bit for the "enemy bombers spotted 9 minutes away from the air base" scenarios If you have 20 minutes warning then the slow climb aircraft can be at combat altitude when the raid gets there (F4F-4s couldn't climb for crap)

If the engine has a good/very good S/C, it still can use WEP as good as the engine that has a meh S/C (other things being equal). See Merlin XX & 45 vs. V-1710-39 and the like, as the three most common Allied fighter engines in 1941-42. WEP was allowed to the Merlins far earlier than for the V-1710s.
If the engine also has an extra S/C gear, it is better still. Again, V-1710 is worse than the Merlin 20 series here.
If the engine is a big one, and has a good/big 2-speed S/C, again the V-1710 comes off as a worse engine.
("V-1710" meaning here the engines installed on the P-40s, P-39s and P-51s)

This does vary a bit from Air Force to Air Force and over time. In 1942 and some of 1943 the US needed general purpose planes. They didn't have the men (flight crews/ground crews) and the number/size air bases they needed in some locations for specialized aircraft. Unless you consider using P-40s as 'top cover' for P-39s
Nowhere near enough P-38s to do all the top cover missions, which is why they used reverse lend lease Spitfires in NA. P-40Fs also sometimes flew top cover for the Allison P-40s and P-39s.

USAAF was flush with the 1st rate single-role aircraft in 1942-43. Talk 7 types of bombers, from the 1- to the 4-engined types? What was lacking was a high-performance fighter in big numbers. Discrepancy between the bombers' and fighters' numbers sometimes made ironical things to happen, like the A-36s flying the fighter cover for the B-25s.
The high-performance fighters were oftentimes the enablers, of force multipliers for the bombers to do their job. Sometimes the AAF was to blame for the lack of these fighters, sometimes the industry was too late on the ball, many times there was a dissonance between what the AAF think they needed vs. the capabilities and intents of the industry vs. the realities of the war.

Just because the P-40 was a good fighter bomber in 1943 does not mean that it was a top-crop fighter in 1941-42.

They had no time to develop any specialized versions aside from pulling out a few guns and a fuel tank.

There was no need to make a specialized version of a P-40. What was needed was the much improved engine in the nose - just like it was true for all the other fighters. No major upgrade of powerplant section as the war progresses = fighter becomes obsolete.

P-40F may not have been as good as was hoped, but the last part of 1942 they only other planes they had were Allison P-40s, P-39s and under a 150 P-38s a month.

All true.
Traces back to the Allison not making even a simple upgrade to the S/C drive (it took them about a full year to fix it to work as hoped?), as well as to the AAF for not jumping on the P-51 bandwagon in a timely manner. The P-47B fiasco contributed a lot here, same with the AAF not ordering the P-38 from a second source, while Lockheed took years to make P-38 into a combat aircraft.

The P-40 wasn't getting respect at the time, the planners wanted the "new" gee-whiz aircraft instead of the old P-40. P-40s were ordered when the new gee-whiz aircraft fell on their faces.

A perfect storm between AAF barking under the wrong tree, and industry many times not being able to deliver or being too late, including the Allison company?

 

[Shortround6]

USAAF was flush with the 1st rate single-role aircraft in 1942-43. Talk 7 types of bombers, from the 1- to the 4-engined types? What was lacking was a high-performance fighter in big numbers. Discrepancy between the bombers' and fighters' numbers sometimes made ironical things to happen, like the A-36s flying the fighter cover for the B-25s.
The high-performance fighters were oftentimes the enablers, of force multipliers for the bombers to do their job. Sometimes the AAF was to blame for the lack of these fighters, sometimes the industry was too late on the ball, many times there was a dissonance between what the AAF think they needed vs. the capabilities and intents of the industry vs. the realities of the war.

Trouble is that often took 1-2 years to get a plane into production in numbers, Ussually a lot closer to 2 years if we are looking at a "new" plane. Work on the B-24 started in Jan 1939.

Just because the P-40 was a good fighter bomber in 1943 does not mean that it was a top-crop fighter in 1941-42.

Again, timing. They flew the Merlin P-40 as a prototype on June 30th 1940, only 2 months behind the first production P-40D was delivered to the US Army. First production plane showed up in Jan 3rd 1942 but deliveries of Merlins to Curtiss were slow, very slow. It took until June to get a fighter group (3 squadrons) equipped with them in the US and about 2 months to get them to a combat area.

There was no need to make a specialized version of a P-40. What was needed was the much improved engine in the nose - just like it was true for all the other fighters. No major upgrade of powerplant section as the war progresses = fighter becomes obsolete.

And yet the Hurricane is somewhat noted for specialized versions. Spitfires are well noted for specialized versions, clip wing, extended wing, unarmed photo recon, cropped impeller low altitude versions and so on.
Granted the Allison P-40s were sort of cropped impeller planes to begin with

A perfect storm between AAF barking under the wrong tree, and industry many times not being able to deliver or being too late, including the Allison company?

Allison gets a lot of blame, not so much the USAAC. Maybe if the Army had paid it's bills in the late 30s ($900,000) Allison would have had more money for better superchargers and/or other improvements. Allison had to "forgive" the debt to get permission to export the engine to France and Britain. Which means they had to make the export engines in order to get paid to put back in the accounts to pay for the R&D on later/better engines.
Allison had made around 30-40 engines total from 1930 to Dec 1939. They made 14,900 engines in 1942.

Now as far as the Curtiss P-60 goes, that was a re-engined XP-53 when the Army's fair haired child (the Continental I-1430) was showing signs of never walking, let alone flying.
Army wanted a lot of stuff from Allison, all the while planning on replacing the Allison with Continental IV-1430 (they even built a new factory to make the IV-1430). Blaming Allison for not spreading out their design team even further in 1940-41-42 seems a little harsh. Please note that this was not helped when the Army decided they wanted the V-1710-C15 engines it be rated at 1090hp at 13,200ft instead of 1040hp at 14,300ft in the spring/summer of 1940. Which meant a whole new 150hr type test. And several failures, some of which were traced to problems in the test stand (too rigid, not enough vibration damping) which lead to Allison having to rebuild 288 (?) engines already built at Allison's expense and the rebuilds included new crankcases. This did lead to a stronger crankshaft and crankcase which was used to advantage in later models of the engine. But it means that the engineering team was scrambling just to stay in business, not looking 1-2 years into the Future.

Unfortunately for the US they had only 6 possible fighter engines in 1942.
And it was not a good selection in 1942. 1943 would be much better.

Curtiss had their own 9 cylinder radial, not a bad engine but not a first rate fighter engine in 1942.
Continental was working on (with army help) the IV-1430 but all that effort was wasted.
P&W had the R-1830 but it was too small and just barely survived against the Japanese in 1942.
P&W had the R-2800 but of the 1079 two stage mechanical engines built in 1942, 670 were built in the last 3 months which means no production planes made it to combat theaters win 1942. The Turbo R-2800 was also a no show in combat in 1942.
Which leaves the 3000 Possible Merlins which the US had contracted with Packard for (Packard delivered 7250 engine in 1942, The US was supposed to get 1/3)
and the Allison.
Going through the list for most of 1942 let alone 1941, the US had the choice of the Allison and the Allison and the...............Allison and the P&W R-1830s in the Wildcats.
Now do you want the 14,900 Allisons as delivered in 1942 or do you want a better Allison in 1942 but fewer of them?

 

[tomo pauk]

Trouble is that often took 1-2 years to get a plane into production in numbers, Ussually a lot closer to 2 years if we are looking at a "new" plane. Work on the B-24 started in Jan 1939.

Seven bomber types in the USAAF inventory 1942-43, from 1-engined attackers to the 4-engined heavy bombers:
A-24, A-36, A-20, B-25, B-26, B-17, B-24.
I haven't bothered with the types we usually don't associate as the real 1-st line assets of the AAF, like the B-18, Vengeance, Ventura, Hudson etc.

tl;dr - AAF was flushed with good/great bombers of any kind, while the fighters were not the 1st tier even if they were numerous

Again, timing. They flew the Merlin P-40 as a prototype on June 30th 1940, only 2 months behind the first production P-40D was delivered to the US Army. First production plane showed up in Jan 3rd 1942 but deliveries of Merlins to Curtiss were slow, very slow. It took until June to get a fighter group (3 squadrons) equipped with them in the US and about 2 months to get them to a combat area.

That is supposed to be June 30th 1941, not 1940.
Note that Merlin is the thing that keeps the P-40 in play - even for any part of 1942 it is still not as good as the best fighters in the world - reinforcing the point that V-1710 behind the curve.

And yet the Hurricane is somewhat noted for specialized versions. Spitfires are well noted for specialized versions, clip wing, extended wing, unarmed photo recon, cropped impeller low altitude versions and so on.
Granted the Allison P-40s were sort of cropped impeller planes to begin with

All of these fighters started out as the pure fighters. 1st job of the Hurricane, Spitfire and P-40 was to kill enemy aircraft, and Spitfire stands out there.
There was no high-altitude P-40, there was no unarmed photo recon version of note of the P-40, there was no great shakes when P-40s were combat tested against the Axis best - lack of a good/excellent engine played a good part there.

Allison gets a lot of blame, not so much the USAAC. Maybe if the Army had paid it's bills in the late 30s ($900,000) Allison would have had more money for better superchargers and/or other improvements. Allison had to "forgive" the debt to get permission to export the engine to France and Britain. Which means they had to make the export engines in order to get paid to put back in the accounts to pay for the R&D on later/better engines.
Allison had made around 30-40 engines total from 1930 to Dec 1939. They made 14,900 engines in 1942.

Army wanted a lot of stuff from Allison, all the while planning on replacing the Allison with Continental IV-1430 (they even built a new factory to make the IV-1430). Blaming Allison for not spreading out their design team even further in 1940-41-42 seems a little harsh.

Allison spread themselves thinly with the V-4320. The later engine was offered by the company to the AAF.
I'm not sure how any why 1940 is mentioned there, Allison started with the higher-geared S/C drive for the V-1710 by some time of Autumn of 1941. It took them more than a year to make the drive reliable.

I don't like the narrative that want's to have people believe that Allison company was never to blame for anything.

Now do you want the 14,900 Allisons as delivered in 1942 or do you want a better Allison in 1942 but fewer of them?

I'm willing to let go 10% or the production if the 9:60:1 drive for the S/C can be had by late 1941 instead of Autumn of 1942.
But the best bet would've been to kill the V-3420, and have both numbers of the V-1710s and the faster S/C drive.

 

[tomo pauk]

Now do you want the 14,900 Allisons as delivered in 1942 or do you want a better Allison in 1942 but fewer of them?

Another thing to add - with the higher speed S/C drive sorted out by winter of 1941/42, rest of 1942 can be used to make the S/C even better (and the V-1710 as whole). Talk a 2-stage S/C, or a big 1-stage S/C with either a fixed drive or a variable-speed drive. With or without the respective intercoolers.
Fuel injection, to put the intake problems to the ground once for all; combine with the increased valve overlap for the ~10% better power.

 

[Shortround6]

A-24, A-36, A-20, B-25, B-26, B-17, B-24.

The A-24 was not first rate, navy use aside it was not what the Army wanted. It was what was available.
Lack of training/doctrine hurt it in Army use. It was also the wrong plane for the area it was employed in to start.
The only Army A-24s to see combat use had the 1000hp engine, I don't know what level of protection (weight) they had.
Getting over the Own Stanley's and/or trying to fly the distances needed to go Island to Island were problems.
A-36 was ordered as a funding trick. Keep the NA production line open while they worked on the Merlin powered version.

I haven't bothered with the types we usually don't associate as the real 1-st line assets of the AAF, like the B-18, Vengeance, Ventura, Hudson etc.

Well the B-18 does make an interesting "what if"
If the war had started in 1937/38
Ventura gets a bit of a bum rap.
fighter escort was in it's infancy (same does apply to the A-24) but the Ventura/PV-1 seems to have preformed rather well in the Pacific.

That is supposed to be June 30th 1941, not 1940.

Yep, fat fingers strike again.

Note that Merlin is the thing that keeps the P-40 in play - even for any part of 1942 it is still not as good as the best fighters in the world - reinforcing the point that V-1710 behind the curve.

I am trying to divorce the airframe from the engine, at least somewhat. The Army wanted new airframes and considered the P-40 Obsolete. None of the New Airframes (Except the Xp-61 and P-63) made it into production (the P-51 dates from just before the Armies love fest with unconventional designs. The XP-52, XP-53, XP-54, XP-55, XP-56, XP-60 and a few others made it into production while sucking up a huge amount of resources in engineering time.
A little more time, in retrospect, with the existing P-40 might have paid dividends.
In 1939-40 a fair amount of interest was also going into the P&W X-1800 engine (think Sabre on it's side) and the earlier mentioned Continental. 1600hp with turbo at 15,000ft was intended in 1940-41 with a two speed supercharger or 1600hp at 25,000ft with a turbo.
Turns out the Allison could eventually reach 1600hp at 25,000ft with a turbo but not until 1944 (?)
The P-40F was doing very well indeed for the installed power considering it's size and weight. Not P-51 class but who else was more than just a few percent off of the P-40 considering it's size/weight? Bf 109 was both small and light.
as a Benchmark the XP-39E (XP-63 prototype?) managed around 386-393mph at 21,680-24,000ft (sources/tests vary) at about 8900lbs using the two stage supercharger. Granted the XP-39 was faster but exact features are hard to determine (guns or no guns and so on).

I don't like the narrative that want's to have people believe that Allison company was never to blame for anything.

Allison did make some mistakes, but again, Allison was rather small company, granted in had GM behind it but GM cars were not exactly leading edge engine wise

Fuel injection, to put the intake problems to the ground once for all;

Army wanted Allison to develop fuel injection in the late 30s.
Allison told them they could not work on all the projects the Army wanted. They didn't have enough engineers. Allison told the army to pick certain projects to get priority.
Army dropped the request for fuel injection.

Please note that Allison had done at least some calculations and/or drawings for the two stage supercharger in 1938 but the first army contract was placed Dec 2 1940.
Things did not go well, Original delivery date of Sept 1941 was pushed back to Feb 1943. A little thing like the war going on
They spent a lot of time in 1942 sorting out the drive to the Aux supercharger. Testbed engine/s were running in Feb 1942. Originally with a simple one speed drive and friction clutch.
Then a hydraulic drive, then a variable speed hydraulic drive.

The P-40 didn't get a "make-over" until the P-40Q. Which was rather late.

 

[tomo pauk]

A-36 was ordered as a funding trick. Keep the NA production line open while they worked on the Merlin powered version.

Too bad that trickery was not used so the AAF gets actual fighter P-51s instead. Make 'A-40s's or 'A-39s' for all I care.

None of the New Airframes (Except the Xp-61 and P-63) made it into production (the P-51 dates from just before the Armies love fest with unconventional designs. The XP-52, XP-53, XP-54, XP-55, XP-56, XP-60 and a few others made it into production while sucking up a huge amount of resources in engineering time.
A little more time, in retrospect, with the existing P-40 might have paid dividends.
In 1939-40 a fair amount of interest was also going into the P&W X-1800 engine (think Sabre on it's side) and the earlier mentioned Continental. 1600hp with turbo at 15,000ft was intended in 1940-41 with a two speed supercharger or 1600hp at 25,000ft with a turbo

Agreed all the way.

Turns out the Allison could eventually reach 1600hp at 25,000ft with a turbo but not until 1944 (?)

The only non-turbo V-1710 capable of such a feat would've probably been the one earmarked for the (X)P-51J, helped out by the intercooler and 3200 rpm operation, and that is well in 1945, best-case. In 1944, the best non-turbo V-1710 (the -121) was good for 1600 HP at 18000 ft (with a bit of ram helping out), or 1190 HP at 25000 ft - see here.

The P-40 didn't get a "make-over" until the P-40Q. Which was rather late.

Main part of the make-over was installation of the 2-stage engine.