wuzak
Captain
Wasn't 3,200 rpm the normal maximum rpm for late model V-1710s with 12 counterweight crankshaft? I.e., not overspeeding?
P40 Vs all other fighters in Europe
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Wasn't 3,200 rpm the normal maximum rpm for late model V-1710s with 12 counterweight crankshaft? I.e., not overspeeding?
The XP-40Q used about 1600 HP at 22000 ft to do 417 mph. Fw 190D-9 used ~1500 PS at 22000 ft for 405-410 mph.
Granted, there was no easy way to beat the P-51 in the "speed vs. HP used @ high altitude" metrics.
P-63's cooling system weighted 356-359 lbs. Lubrication system was 135-137 lbs. P-51B cooling system was 663 lbs (including the intercooling circuit?), lubricating system was at 101 lbs.
Supermarine squeezed the 2-stage Griffon on the Spitfire, FW hooked the long and heavy Jumo 213 and DB 603 engines on the small Fw 190 and Ta 152 fighters. IMO, the only problem with a 2-stage Griffon + P-40 was that there was no steady flow of these engines for wide use.
1-stage Griffon will meant a 400 mph P-40.
So the D-9 was quite a bit deficient in performance and not equal to the Spitfire Mk XIV and P-51 at all as often propageted?
Shortround6
Lieutenant General
The single stage Griffon went around 1790lbs
A two stage Griffon went over 2000lbs. Two stage needs a bigger intercooler than the Merlin.
You can get it in but it is going to need a lot of work.
The P-40 was a lot heavier than a Spitfire. A Spit MK XIV was about 400lbs lighter than the XP-40Q tested. The Spit had two 20mm and two .50 instead of four .50 cal (or ballast).
A MK XII was about the same weight as a MK IX. They were both lighter than a P-40N-1 (without electric starter and normal battery and without 3rd fuel tank) by about 300lbs.
Yes you could make a better P-40, but it was going to take a lot of work and it would NOT be better than a P-51 and any improvement to the Spitfire is debatable.
The "improved" P-40s all sacrificed armament (and ammo capacity).
A two stage Griffon went over 2000lbs. Two stage needs a bigger intercooler than the Merlin.
You can get it in but it is going to need a lot of work.
The P-40 was a lot heavier than a Spitfire. A Spit MK XIV was about 400lbs lighter than the XP-40Q tested. The Spit had two 20mm and two .50 instead of four .50 cal (or ballast).
A MK XII was about the same weight as a MK IX. They were both lighter than a P-40N-1 (without electric starter and normal battery and without 3rd fuel tank) by about 300lbs.
Yes you could make a better P-40, but it was going to take a lot of work and it would NOT be better than a P-51 and any improvement to the Spitfire is debatable.
The "improved" P-40s all sacrificed armament (and ammo capacity).
wuzak
Captain
And radiator.
Early Spitfire XIVs had 2 x 20mm and 4 x 0.303". The XIVe got the 2 x 20mm + 2 x 0.50", but I'm not sure how many of each type were built.
The early Spitfire XIV had the universal wing, which could accommodate 4 x 20mm if required. Only a few Mk Vs were so equipped.
The E-wing was modified from the universal C-wing, so, in theory, the XIV could have used 4 x 20mm.
There were so few Griffons available that they only built 100 Spitfire XIIs. Why would they use them to power P-40s when they had already determined that the Spitfire airframe was better for their purposes?
Above 20000 ft, the two Allied fighters were far better.
Between SL and 20000 ft, I'd say these were about equal, though the Spit 14 was the best climber between the 3 of them at any altitude. Push to install the 2-stage Jumo 213F on the later Ds was justified (so was the installation of the 213E or the DB 603L on the Ta 152), but it was also too late, the 213F starting to materialize some time in 1945.
Admiral Beez
Major
Could the supercharger used to make the Allison superlative on the P-38 have been used on the P-40 with similar, albeit single engined effect?
You need a different plane, to build in a set up like the P-47. This was a consideration when RR were thinking about the two stage Merlin, If they went down the supercharger route, it would go in a Wellington without a problem but what about a Spitfire Hurricane or other.
Shortround6
Lieutenant General
The is most of the extra stuff the P-38 supercharger needed. A few things, like oil coolers were common to both engine set ups.
This is a late model P-38 with the intercooler in the bottom of the Nacelle.
American Turbos just about always had a number of feet between the engine and the turbo, quite possibly to allow the exhaust gases to cool off just bit Some P-38s had pieces of armor plate to shield the cockpit from the exhaust turbine.
Now see this picture.
two oil coolers under the prop, the big opening is the intercooler. Now note the radiators in the back of the booms. If you are trying to cool engines making at 1425hp at 25,000ft you need a lot more airflow than using 1150hp at 15-16,000ft (P-40N engine) and even it you can use WER at 10,000ft of 14,000 you still can't cool the engine using the standard P-40 radiators .
It is the extra volume of the air ducts and intercoolers and the larger radiators that would cause such a problem with a turbo P-40. (that or do away with the intercooler and use a crap load of water-alcohol). It may be able to do it but the changes are play havoc with any back of the envelope estimates of speed/performance.
Admiral Beez
Major
Interesting. How much of that plumbing and cooling could they omit with a Merlin or Griffon powered Lightning? The DH Hornet seems very aerodynamically clean in comparison, with P-38 performance to boot.
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Shortround6
Lieutenant General
it was clean, but then they stuck the radiators and intercoolers in the wing leading edge.
It wasn't that the Merlins could do away with all the lumps and bumps. It was that the P-38 was designed several years earlier and it was designed for 1100hp engines. The intercoolers and radiators designed for 1100hp engines weren't big enough for 1425-1600hp engines and they had to just do minimum changes to get the engines to work.
The DH 103 not only used several years worth of radiator design work from the Mosquito it used a special version of the Merlin to make the engine as compact as possible much. Mostly by changing the layout of the accessories.
P-38 have had a number of details that were adding to drag and thus both robbing the speed and/or lowering the critical Mach number. The ram air intake was a draggy detail, Hornet had those designed better - in the wing leading edge outboard of engines (switch from updraft to downdraft carbs made that possible). Cooling air inlets for the turbines also added to the drag, so did the 'dirty' area around the turbines; there is probably no easy way around this?
Canopy was draggy, NACA sugested a more slanted front part of it as well as a more smooth and longer read end of the pod - those changes also improved the critical Mach number. They also suggested elongating the chord of the inboard portion of the wing by either 10 or 20% (makes the thickness-to-chord ratio lower, thus much improving the critical Mach there), in later case the coolant and oil radiators were to go in the extension to both keep CoG undisturbed and to lower the drag even further.
(another suggestion was to make the inner portion of the wing in a new laminar flow airfoil, but that would've required a wholesale change of that portion of the wing)
Unfortunately, these NACA suggestions never made it in the production P-38s.
After everything is said and done, retrofit of a 2-stage superchaged engine in place of an 1-stage S/Ced engine was a far easier thing to make.
Venturi
Airman
Overweight,
Or overbuilt?
How many Gs in multi-axes was say the Spitfire able to take (or even rated for) compared to the P40?
Increased airframe strength costs,
And that is in weight.
Additionally range costs weight,
And the P40 had much more than the Spit.
Compare it to the P51, and it is lighter.
More advanced Aerodynamics and two stage supercharger are what was lacking. But compared to fighters of similar design age, aerodynamics were fine. Maybe not as superlative aero as the Spitfire.
Or overbuilt?
How many Gs in multi-axes was say the Spitfire able to take (or even rated for) compared to the P40?
Increased airframe strength costs,
And that is in weight.
Additionally range costs weight,
And the P40 had much more than the Spit.
Compare it to the P51, and it is lighter.
More advanced Aerodynamics and two stage supercharger are what was lacking. But compared to fighters of similar design age, aerodynamics were fine. Maybe not as superlative aero as the Spitfire.
Shortround6
Lieutenant General
The P-40 got into action (and I mean just flying in squadron service) late after a long, long development. Counting the P-36 here.
However the P-40 was a large extent, all that was available in 1940/41/42.
The Allison engine also took too long to get into "world" standards.
The US Army didn't help with unrealistic expectations for armament.
From AHT.
Type...........total production by end 1942..............production in 1942 alone
P-38............................1687..........................................................1479
P-39............................2871..........................................................1982
P-40...........................6883...........................................................3854
P-47...........................533...............................................................532
P-51 (*)....................772................................................................634
F4F.............................1900...........................................................1470
F4U............................179................................................................178
F6F..............................10...................................................................10.
F-51 does not include A-36 production.
Allison did a heck of job building the Allison, especially for a engine company that had only built under 100 engines during the 1930.
But the Allison's of 1940 were NOT up to standards of either Britain or Germany. By the time Curtiss had built the first 100 P-40s the British were building Spitfires IIs with Merlin XIIs and the first Hurricane IIs with Merlin XXs were just leaving the factory. The P-40 would not see a Merlin XX for about one more year and would take another 6-9 months for production P-40s with Merlin engines to show up. Bf 109Gs were showing up in combat before the Merlin powered P-40s showed up. It took Allison about 1 year get the 1150hp rating up to 15-15,000ft over the 11,500hp attitude. This was over 1 1/2 years from even the Merlin 45.
Had Allison been able to get the 9.60 gears into production in Dec 1941 and had the P-40 been saddled with 300-400 less armament weight (and a bit less structural weight) then it might have been closer to it's adversaries.
With 1040-1150hp engines the idea that you could stick over 1000lbs of guns and ammo inside the wing the P-40 and not cripple the performance is a source of wonderment.
Granted it was not often (if ever?) used but how much of the weight increase of the wings (and other things) from the P-40C to P-40D was due to increase in armament weight.
Which cannot be taken back out as easily as just taking out guns and ammo.
However the P-40 was a large extent, all that was available in 1940/41/42.
The Allison engine also took too long to get into "world" standards.
The US Army didn't help with unrealistic expectations for armament.
From AHT.
Type...........total production by end 1942..............production in 1942 alone
P-38............................1687..........................................................1479
P-39............................2871..........................................................1982
P-40...........................6883...........................................................3854
P-47...........................533...............................................................532
P-51 (*)....................772................................................................634
F4F.............................1900...........................................................1470
F4U............................179................................................................178
F6F..............................10...................................................................10.
F-51 does not include A-36 production.
Allison did a heck of job building the Allison, especially for a engine company that had only built under 100 engines during the 1930.
But the Allison's of 1940 were NOT up to standards of either Britain or Germany. By the time Curtiss had built the first 100 P-40s the British were building Spitfires IIs with Merlin XIIs and the first Hurricane IIs with Merlin XXs were just leaving the factory. The P-40 would not see a Merlin XX for about one more year and would take another 6-9 months for production P-40s with Merlin engines to show up. Bf 109Gs were showing up in combat before the Merlin powered P-40s showed up. It took Allison about 1 year get the 1150hp rating up to 15-15,000ft over the 11,500hp attitude. This was over 1 1/2 years from even the Merlin 45.
Had Allison been able to get the 9.60 gears into production in Dec 1941 and had the P-40 been saddled with 300-400 less armament weight (and a bit less structural weight) then it might have been closer to it's adversaries.
With 1040-1150hp engines the idea that you could stick over 1000lbs of guns and ammo inside the wing the P-40 and not cripple the performance is a source of wonderment.
Granted it was not often (if ever?) used but how much of the weight increase of the wings (and other things) from the P-40C to P-40D was due to increase in armament weight.
Which cannot be taken back out as easily as just taking out guns and ammo.
drgondog
Major
I would argue the point "P-51D was not a good climber when compared to Fw 190 and Bf 109". It was, at 67" vs 1.42 ata for Bf 109G-6 and 1.42 ata vs Fw 190A-7 and A-8 at Combat Weight GW at T.O. Only (USAAF) the P-47M and P-38J with FULLY functional engines outclimbed the P-51B/D through 25K, After 25K the P-51B/D caught up and passed. With 75" the P-51B/D easily outclimbed the 109 as medium altitudes were reached with 1650-7 engine and continued to increase at higher altitudes. The Spit IX and XIV easily outclimbed every Mustang save XP-51F/G and P-51H.
In "Bastard Stepchild" II presented the comparative data and graphics at full combat gross weight (internal) and included wing racks for the P-51B/D. I had Kurfurst (Dr. Millei Adam) check my data to make sure I wasn't understating the 109 and 190 values. BTW the P-51D with new cleaner bomb racks at Same GW as P-51B outclimbed and out ran the P-51B at any Boost. Note - when I say 'Same' I mean both at 9600 pounds with 1650-7, 67", 3000 RPM. That P-51D TO was 500 pounds less than full internal loading of fuel, oil and ammo.
To the question of P-40 combined with 1650-3 or -7, it would certainly enabled better performance in both climb and straight away speed, climb comparable or better to P-51B/D due to lower W/L but the P-40 Parasite Drag was more than 30% greater than P-51B/D which would kill much of the speed potential to be gained with the heavier more powerful engine.
That said, Packard could not come close to production quantities committed for RAF/RCAF and the Mustang - which also impacted the projected spares commitment in 1944. Echols in a huge brainfart (malice?) approved a thousand 1650-1 spares (in Summer 1943) for Q1 1944, and if read between the lines - got his ass kicked because P-51B- airframes were complete save engines into August 1943. The ONLY hope for Curtiss to upgrade performance on P-40 airframe was the two stage Allison installed on the P-40Q.
The P-40 maxed out internal fuel at 161 gallons, with growth limitations in aft fuse 62 gal tank (CG), and further increases in wing storage due to landing gear and gun arrangements. That would have yielded perhaps 170 mi combat radius with external drop tanks under ETO escort planning guidelines
EDIT - The Brain Fairy was shacked up when I was calculating this - I can ony point to botched pacemeker op that I redo next week.
As Tomo pointed out, internal 161 gal with an external Combat tank would have been less than a P-51B (with 180 gal internal plus twox75s) but better than P-47 w/75 gal tank - at significanly lower altitude
In "Bastard Stepchild" II presented the comparative data and graphics at full combat gross weight (internal) and included wing racks for the P-51B/D. I had Kurfurst (Dr. Millei Adam) check my data to make sure I wasn't understating the 109 and 190 values. BTW the P-51D with new cleaner bomb racks at Same GW as P-51B outclimbed and out ran the P-51B at any Boost. Note - when I say 'Same' I mean both at 9600 pounds with 1650-7, 67", 3000 RPM. That P-51D TO was 500 pounds less than full internal loading of fuel, oil and ammo.
To the question of P-40 combined with 1650-3 or -7, it would certainly enabled better performance in both climb and straight away speed, climb comparable or better to P-51B/D due to lower W/L but the P-40 Parasite Drag was more than 30% greater than P-51B/D which would kill much of the speed potential to be gained with the heavier more powerful engine.
That said, Packard could not come close to production quantities committed for RAF/RCAF and the Mustang - which also impacted the projected spares commitment in 1944. Echols in a huge brainfart (malice?) approved a thousand 1650-1 spares (in Summer 1943) for Q1 1944, and if read between the lines - got his ass kicked because P-51B- airframes were complete save engines into August 1943. The ONLY hope for Curtiss to upgrade performance on P-40 airframe was the two stage Allison installed on the P-40Q.
The P-40 maxed out internal fuel at 161 gallons, with growth limitations in aft fuse 62 gal tank (CG), and further increases in wing storage due to landing gear and gun arrangements. That would have yielded perhaps 170 mi combat radius with external drop tanks under ETO escort planning guidelines
EDIT - The Brain Fairy was shacked up when I was calculating this - I can ony point to botched pacemeker op that I redo next week.
As Tomo pointed out, internal 161 gal with an external Combat tank would have been less than a P-51B (with 180 gal internal plus twox75s) but better than P-47 w/75 gal tank - at significanly lower altitude
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Yes, going with a 2-stage engine from Allison is the only plausible way.
I'm sure that a P-40 cannot fulfil the ETO escort planing guidelines, the engine as-is does not give enough of power for cruising at 310+- mph TAS at 25000 ft. The 2-stage V-1710 should be capable for that. I'd try and nick the drop tank from the P-38, but that's just me.
Bill - we'd probably get a lot more than 170 miles with 160 + 150 gals of fuel? P-51B was good for 460 mile radius with 180 + 150 gals under the 'ETO rules'.
drgondog
Major
All about GW compared to Design weight. ALL fighters grew in GW as missions dictated changes and new equipment. IIRC the Spit (original) was designed to 7G Limit and 10.5 G Ultimate to its original design GW. Comparably the P-40 original Empty Weight was 5367/Combat GW = 6807 designed to 8G Limit and 12G Ultimate. As Combat Weight of the P-40F was 7069 pounds, reducing Limit load to 7.7 G.
What you must do to compare is to a.) Understand Brit vs US structure limits standards, b.) the original Gross Weight of the aircraft for which the Design Limit Load existed, and c.) The growth of the GW overtime and how that reduced allowable Limit Loads.
drgondog
Major
Tomo - yes. Brainfart. It would have been comparable to P-38 with 300gal internal fuel and external 300 gals.
The Spitfire was around 2 years before the P-40 in development (based on first flights of prototype and production machines), I dont think there was any issue with what it could do as regards "G" forces in multi axes in flight was there? There were issues on landing loads. The late war Griffon versions were very heavy machines, but the wings were substantially modified, though they looked pretty similar.
Bill,
I understand the comparison of Combat GW between the planes, but how did the climbs compare when they met in battle? How about a Mustang with approx half gas, compared to the 109 / 190 both at half fuel load (weight)? I would think less 1/2 gas in a P-51 would result in a greater percentage of weight gone, and a much better climb rate.
Cheers,
Biff
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