How good was the soviet air force? (1 Viewer)

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Venomstick121 Venomstick121 , you might want to pay attention to pben's post. This is an important aeronautical detail that other sites frequently miss.
The Trinity test? Don't believe it. Someone tested balkenkreuzes on a Groundhog. It was too much for time space continuum to contain, resulting in a mighty cataclysm.
All forms of reality television have been traced back to that event. It may eventually end civilisation.
 
Corrected the minor historical detail.
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That is a photo shop job. The B Siebzehn fliegenschlossbetrieb flew too high and fast for any camera of the day to capture it on film. This is why it was used to escort V2 rockets, Not a lot of people know that, but you just read it on the net, so it is a FACT.

Rumors spread by the same crowd who always claim that the Germans lost the war, and that they had bad social policies.
 
I read the reports from the war. Many of them (too many!) pointed out that due to the poor manufacturing quality of the Yaks in mass production, their flight performance was deteriorating. For example, the maximum speed of mass-produced fighters ranged between 615-620 km/h, while polished airplanes on state tests got 650 km/h. This is not my fantasy. These are the REPORTS of the control tests.

This is common to most single seat fighters in WW2.

For instance, 1942 testing by the RAF of 10 production Spitfire Mk Vs in showed no aircraft was capable of making the same speed as the initial (production) examples tested. The best was 3 mph (5 kph) down, the worst was 20 mph (32 kph) slower. On average, they were 11 mph (18 kph) down on early production examples.

Similar story with the Mk IX. Testing of some in service aircraft in late 1943 showed a variation of as much as 25 mph compared to testing examples. A 1943 report from the RAE stated that Mk Vs could lose up to 40 mph (64 kph) and Mk IXs up to 30 mph (48 kph) due to a combination of fit, finish and equipment.

German fighters were the same. Messerschmitt testing of serial production 109 Gs at sea level in 1942 showed they were, on average, 8 kph slower than test examples. Later testing showed some aircraft were underperforming 'guaranteed' speeds by as much as 30 kph at full throttle altitude.

The RAAF reported something similar with it's P-40Es and P-40Ns. When their new P-40Ns showed up, maximum performance of was 352 mph - against a factory standard of 364 mph.
 
These things were also affected by various pieces added to the aircraft - antenna masts, bomb racks, rearview mirrors, in the case of Spitfires the external BP windscreen that some of them had, and also little things like whether the gun barrels were taped over.

For both US and British aircraft, when there was a big production run they often engaged multiple firms in the production. Some excelled, some lagged. It wasn't as bad as the problems the Soviets had especially in the first 18 months of the war, but it was certainly a problem.
 
Right, and by late 1942 the Russians, Australians, British, and US were all already using higher boost ratings of 56" or 60' for the V-1710-73.

US Specific Engine Flight Charts for 18 Dec 1942 has the V-1710-39 (P-40D, E, E1) rated at 56" and the V-1710-73 (P-40K) at 60". At least officially.


However, there's a 12 Dec 1942 memorandum from Allison's chief engineer to the Army Air Forces confirming reports that Australian pilots report operating at around 70" for "prolonged periods", while Allison representatives in the Middle East were "resetting boost controls" for the -F3R (the -39) and -F4R (the -73) engines to "66.

Allison was sort of gratified that it's engines were standing up to this, and sort of horrified as new engines with different supercharger blower ratios (9.6:1 vs 8.8:1) were more likely to fail at these sorts of pressures.

 
US Specific Engine Flight Charts for 18 Dec 1942 has the V-1710-39 (P-40D, E, E1) rated at 56" and the V-1710-73 (P-40K) at 60". At least officially.


However, there's a 12 Dec 1942 memorandum from Allison's chief engineer to the Army Air Forces confirming reports that Australian pilots report operating at around 70" for "prolonged periods", while Allison representatives in the Middle East were "resetting boost controls" for the -F3R (the -39) and -F4R (the -73) engines to "66.

Allison was sort of gratified that it's engines were standing up to this, and sort of horrified as new engines with different supercharger blower ratios (9.6:1 vs 8.8:1) were more likely to fail at these sorts of pressures.


Yeah that (Dec 1942) Allison memo is also here http://www.wwiiaircraftperformance.org/P-40/V-1710_Service_Use_of_High_Power_Outputs.pdf

There is another one to do with Allison engined P-51's in British use being pushed to 70" as well.

The situation described in that memo by the somewhat horrified Allison executives springs from the steep learning curve followed by the units using "Kittyhawk" / Hawk 87, which started with the RAF using P-40D / Kittyhawk I in North Africa at the end of 1941, and soon after went into action (with P-40E) briefly in the Philippines and Java, and then in Australia and New Guinea both by US (49th FG) and Australian (75, 76 RAAF) units. These people got the manuals with the lower (45" Hg) max engine settings, which they more or less threw out the window due to the extremely difficult tactical situation. By mid 1942 they had determined in the field that a 55-60" Hg maximum boost was acceptable, and this started a flurry of communication with War Department, Curtiss, and Allison, and Allison did some strengthening of crank shaft, crank case, and bearings to accommodate the harsher use.

The Allison memo at the end of 1942 corresponds with the updated flight manuals etc.

The Soviets clearly went through the same thing with the P-40 though we don't really know the details, except for a few comments made during pilot interviews. When they did their workup on the P-39 in early 1943, they already knew the (higher) safe limits.

As you noted, the 9.6:1 blowers, which were designed to give the P-40 a higher critical altitude, would not tolerate the 60" and higher boost, so the WEP setting became either 56 or 57" for most Allison versions. The Merlin engined variants, which were the most important US type in the Med, had a different history but also increased their boost ratings.
 
This came up in another thread, so good some articles on the Soviet use of the P-39 (sorry)




Some bullet points just from the first article -

First ~200 x P-39s (P-39D-2) came from Britain (as Airacobra I) starting in December 1941, along with some Hurricanes. (Via highly perilous northern route, 49 P-39s were lost with convoy PQ_17)
American deliveries started in Spring 1942

Of the types of planes (this was something debated in other threads recently): "At the beginning stage British deliveries favorably compared with American deliveries, which began to arrive significantly later, in early 1942. And if the positive aspects of British assistance were obvious only until July 1942 (later it began to fall behind by almost all measures), then the practice of designating for the USSR only second-rate combat equipment had a place throughout the entire war."
Also later:
"a significant portion of the Hurricanes and P-40Cs that had arrived earlier had been flown for some time in the RAF and had exhausted a significant percentage of their use life. Representatives of the military commission of the USSR in Great Britain had noted cases when new aircraft arriving from the USA were taken into the inventory of the Royal Air Force to replace other aircraft already in use. These aircraft underwent repair, were disassembled, packed in crates, and sent to the USSR. It is difficult to judge the British for this because the first aircraft we received were not from Lend-Lease but from those purchased for the RAF. Similar cases with aircraft of American production practically ceased to occur after the beginning of deliveries by Lend-Lease. We continued to receive "previously used" British aircraft until the end of the war, though not in great numbers."

Airacobra vs Spitfire "Returning to the Airacobra, it must be noted that the British somewhat underrated it. Soviet pilots preferred the Cobra despite its many shortcomings to any other aircraft received from the Allies, including the Spitifire VB, which the British deigned to give us only in 1943."

Why the Soviets liked it: "The Airacobra almost ideally corresponded to the nature of combat activities on the Soviet-German front. Here the struggle was not for absolute air superiority, but for superiority over specific areas of active combat activities. Dive bombers and close support aircraft, that is, aircraft directly supporting ground forces, operating at low altitude over the battlefield or at medium altitudes in the operational-tactical airspace, were the basis of both the Luftwaffe and the VVS Red Army. Correspondingly, the fighters had either to counter the enemy's fighters, or accompany one's own bombers at those same altitudes. Air battles rarely occurred at altitudes above 5,000 meters. In these working environments the Airacobra just had the best flight characteristics. If one adds to this good maneuverability, easy handling, powerful armaments, and excellent vision, then its success on the Soviet-German front becomes obvious."
A few of the first P-39s went to 78th IAP (fleet defense) and 19th GIAP (Karelian Front, near Finland)

Most went to 22nd ZAP (Reserve Air Regiment) training center. They also assembled and trained Soviet pilots for Hurricanes and Kittyhawks at this center. From Dec 1941 - April 1942 the Soviets did an extensive 'workup' on the P-39. This included ironing out minor technical problems, winterization, training, and evaluation for development of tactics and the writing of a Soviet pilot manual. Later 14th ZAP also got involved in this effort.

British technicians were on-site and did help with the workup: "there was a group of British RAF specialists at 22 ZAP, engaged in assisting in the assimilation of the Hurricanes. The leader of this group, an engineer in the rank of captain, fortunately also spoke French. In addition, some of his team members were familiar with the Airacobra. Therefore the consultations went something like this: I. G. Rabkin submitted questions of interest to the British engineer in French. He consulted with his colleagues in English and responded to the questions in French. Our leader passed along the responses to his subordinates in Russian. This process somewhat speeded up the work for translating the instructions."

They initially missed some of the negative features: "The flat spin, the engine throwing connecting rods, and other manifestations were yet to be discovered."

Soviet officials blocked information about Lend Lease and foreign aircraft types: "This myth [of P-39 being used for ground-attack] arose out of an insufficiency of information: both Soviet official and memoir sources were carefully screened by Glavlit [political censorship overseeing publication of all printed material in the USSR] and stood on the "only believable" conceptual positions, and almost until the 1970s attempted to conceal any information about Kittyhawks, Cobras, and Hurricanes, as though they almost never existed."
First units:

153 IAP (later 28th GIAP)

"The 153d IAP, at full strength, was formed on the basis of TOE 015/284 (2 squadrons, 20 aircraft and 23 pilots), under the command of Hero of the Soviet Union Major S. I. Mironov, arrived at Voronezh airfield on 29 June 1942. It began combat operations without any delay, on 30 June 1942. Later the regiment was relocated to Lipetsk airfield, from which it operated until 25 September 1942. In 59 flying days on the Voronezh Front the regiment conducted 1,070 combat sorties with 1162 hours of flight time; fought 259 aerial engagements, of which 45 were of a group nature; shot down 64 enemy aircraft, of which 18 were bombers (15 Ju-88, 1 Do-217, 1 He-111, and 1 FW-198), 45 fighters (39 Bf-109F, 1 Bf-110, 1 Me-210, 4 MS-200), and 1 aerial observation aircraft. Losses during these three months of combat were 3 pilots and 8 aircraft. "These relatively insignificant losses are explained in the first place by the experience of the pilots and the good flight performance characteristics of the Airacobra aircraft." Regiment commander Lieutenant Colonel Mironov, HSU (TsAMO, collection 28 Guards IAP, index 143456, file 1) [TsAMO – central archive of the Defense Ministry]."

185th Red Banner IAP
(This is a fleet defense unit. Apparently there is no data on this unit)

180th IAP (later 30th GIAP)

"30th Guards IAP (later 30th Guards Baranovicheskiy Red Banner IAP) arrived at 22d ZAP on 20 July 1942, having lost in about a month of combat the greater part of its Hurricanes. (The regiment had been sent to the front from 22d ZAP with 20 Hurricanes on 12 June 1942.) The unit began transition to Airacobra I aircraft on 3 August 1942. It left for Chernava airfield in the Central Front on 13 March 1943, formed with TOE 015/174 (3 squadrons, 32 pilots). The total flight time during the transition period from 5 February through 12 March 1943 was 510 hours (1,649 landings). Airacobras AH584, 599, 634, BX/AP (?) 265, 275, 282, 316, 321, 355, 359, and 370 were issued to the regiment. Materials regarding the combat efforts of the regiment in 1943 have not been preserved."
There is a seperate interview with a 30 GIAP technical officer here Cobra's in 30 GIAP – Lend-Lease

145th IAP (later 19th GIAP)

"This regiment was the first in the Soviet VVS to begin combat actions in the Airacobra I. In distinction from the 153d and 185th IAP, which trained in a rear-area training center, the 145th IAP mastered the imported fighter directly in its operational zone (less than 100 km from the front line), without any kind of instructions, guidance in the Russian language, or assistance of instructors.

The 145th IAP (14th Army, Karelian Front on the Murmansk axis) was formed on 17 January 1940 in the settlement Kayrelo (former territory of Finland). It participated in the Finnish campaign, shot down 5 enemy aircraft and lost 5 of its own. It began the war in the I-16, then flew the LaGG-3, MiG-3, and Hurricane. On 4 April 1942, for successful combat effort, the 145th IAP was designated 19th Guards IAP. At the end of this same month it received the tasking to transition over to the Airacobra I and P-40E Kittyhawk fighters.

(snip)
On 15 May, 19th Guards IAP was relocated to Shonguy and began combat operations, now equipped with 16 Airacobras (including AH618, 619, 660, 664, 679, 692, 697, 703, 708, 709, 713, and 724) and 10 P-40Es.
(snip)
May 1942-received 16, lost 2; June-3 and 5 correspondingly; July-5 and 3; no subsequent issue of aircraft, but losses: August-1, September-2, October-none, and December-1. Altogether to the end of 1942, 14 Airacobra I aircraft were lost (10 were shot down in combat, 1 did not return from a combat sortie, 1 catastrophic loss [9], and 2 by accident),

On 1 January 1943 the 19th Guards IAP had 11 Airacobra I aircraft on hand

Concerning losses inflicted on the enemy by the Airacobra pilots, it is difficult to judge according to regiment reports because until November, Airacobras and Kittyhawks flew together.
To the period ending on 31 December 1943, 19th Guards IAP flew 7,451 combat sorties with a combined 5,410 hours 19 minutes. They shot down Bf-109E-56, Bf-109F-43, Bf-109G-14, He-113-1, Bf-110-30, Ju-88-7, Ju-87-9, He-111-1, Do-215-2, Hs-126-5, Fi-156-1, and FW-189-1. During this time the regiment's losses were pilots-46 (of these 35 in combat), aircraft-86 (of these, 59 shot down in combat, 20 of which were Airacobras). Non-combat losses were 3 catastrophic losses (of these, 1 Airacobra). A total of 128 aircraft were input to the regiment, of these 56 Airacobras.


On the use of Aircrobra 1
"The Airacobra I was actively employed in the Soviet VVS for approximately a year, from June 1942 until the early summer of 1943. Subsequently losses in this air frame were compensated for by deliveries of the later models. The last two Airacobra Is arrived in the USSR in January 1943."
On Soviet contribution to the development of the aircraft:
"It is not an exaggeration to say that Soviet pilots and engineers, front-line troops and researchers, gave their maximum effort to turn the Airacobra into a fully capable combat aircraft. And in doing so they saved the Bell firm from great unpleasantness associated with the production of a series of "unfinished" aircraft. But more about this in the following chapters."
 
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From part 2:

P-39D-2 was the next type. Came via "Southern Route". Training unit was 25th ZAP, "Southern training center" from Oct 1941-July 1943, in Azerbaijan.

Trained 5th, 298th, 16th Guards, and 494th IAP on Airacobras.

Models included D-2, K, L M and N.

Units

298th IAP (later 104th GIAP)

"This regiment was formed on TOE 015/174 and had 32 Airacobras, type P-39K-1 and P-39D-2. Almost two-thirds of its aircraft were D models... The regiment commander, chief of gunnery service, navigator, and squadron commanders and zampolits [political officers] all received the P-39K, while the flight commanders and all remaining pilots received the P-39D-2."

"...went into combat on 17 March 1943 from Korenovsk airfield, in the Kuban, as part of the 219th Bomber Division, 4th Air Army. The regiment fought in this subordination for the entire extent of the celebrated air campaign over the Kuban. It fought against the best German fighter squadrons: JG 51 (Mulders) and JG 3 (Green Hearts). During the period from 17 March to 20 August 1943, the regiment flew 1,625 combat sorties with a flight time of 2,072 hours. It conducted 111 aerial engagements, in which it shot down 167 and damaged an additional 29 enemy aircraft. Its losses were 30 Airacobras destroyed and 11 damaged."

Designated 104th GIAP in August 1943.

45th IAP (later 100th GIAP)

Trained in flying, 112 gunnery training flights. Total flight time 671 hours in training.

In combat 16 February 1943. 31 pilots, 18 with combat experience. "10 P-39D-2 aircraft, 11 P-39K-1 aircraft, and 9 P-40E aircraft. The Airacobras were in the 1st and 3d Squadrons, the Kittyhawks in the 2d Squadron."

"Altogether during two months of intense aerial combat over the Kuban, pilots of 45th IAP shot down 118 German aircraft, losing 7 Airacobras shot down and 8 damaged in combat or in accidents, 1 P-40E shot down and 1 destroyed in an accident. The regiment had the best results in the theater and was quickly, already by 10 May, re-equipped with new models of the Airacobra: P-39L, M, and N. The surviving intact old P-39D-2s (138416, 429, 456, and 458), P-39K, and P-40Es were handed off to the 16th Guards IAP and 298th IAP."

Desginated 100 GIAP in June 1943

16th GIAP

"This regiment was the only one transitioned at 25th ZAP that had received its Guards designation (8 March 1943) before the receipt of the Airacobras."


Noting that this contradicts a recent statement in another thread.

This was Pokryshkin's unit.

"Most famous fighter regiment in the VVS". Went into action in April 1943
"
The regiment began combat operations on 9 April, at the very beginning of the battle for the Kuban. This campaign is considered pivotal in the history of Soviet VVS. Over the course of two months of intense battles with the best fighter squadrons of the Luftwaffe, Soviet pilots won strategic superiority in the air. Approximately 1100 German aircraft were destroyed, some 800 of them in the air. Western historians call this battle the "Stalingrad" of the Luftwaffe.

The pilots of the regiment fought combat operations of a corresponding nature with German fighters. The outcome of the battles in April: 289 Airacobra and 13 Kittyhawk combat sorties, in which were conducted 28 aerial engagements. Shot down were Bf-109E-14, Bf-109F-12, Bf-109G-45, FW-190-2, Ju-88-4, Do-217-1, and Ju-87-1. Of these, Guards Captain A. I. Pokryshkin shot down 10 Messers, Guards Senior Lieutenant V. I. Fadeev 12-Bf-109s, and Guards Senior Lieutenant G. A. Rechkalov 7 Messers and 1 Ju-88."


494th IAP
played only a small part in combat operations, completing altogether 62 combat sorties (44 hours). The regiment downed 3 enemy aircraft with the loss of a single Airacobra and pilot. It was folded into the 22d ZAP on 1 December 1943.

Russian assessment:

"Drawing conclusions, it can be said that the debut of the Airacobra in the Soviet VVS was singularly successful. In skilled hands it was a powerful weapon, fully on a par with the enemy equipment. There was no "special" operational environment for the Airacobras-they were employed as normal multi-purpose fighters that fulfilled the same roles as Lavochkins and Yakovlevs: they contested with fighters, escorted bombers, flew on reconnaissance, and protected our ground forces. They differed from Soviet-produced fighters in having a more powerful armament, survivability, and a good radio, and fell behind our fighters in vertical maneuverability, capability to withstand excessive G-forces, and to execute acute maneuvers. The pilots loved their Airacobras for comfort and good protection. As one P-39 pilot expressed it, he felt like he was "flying in a safe". Airacobra pilots did not burn because the aircraft was metal and the fuel cells were positioned far away in the wing. They were not subject to jets of steam or streams of oil because the engine was behind them. Their faces were not beat up on protrusions of the gunsight. If the airplane should happen to flip over on landing, they were not turned into lump of flesh, as happened to twice HSU A. F. Klubov after transitioning from a P-39 to an La-7. There was a kind of mystical belief that a pilot attempting to preserve a damaged Cobra by belly landing it would almost always emerge not only alive, but also undamaged. But if he bailed out of the same airplane he often was seriously injured or killed by the stabilizer, which was on the same level as the door."
 
In relation to the timing of the first US Lend Lease aid to the USSR, the timescale looked like this:-

Late July 1941 Harry Hopkins, Roosevelt's "Special Assistant" on Lend Lease dispatched to Moscow to find out what the Soviets wanted. He returned via London and discussions with Churchill on the Prince of Wales en route to the conference with Roosevelt at Placentia Bay in Aug.

Outcome of that conference was that Averell Harriman (US Lend Lease representative in London) and Lord Beaverbrook (British Minister of Supply) were sent to Moscow to negotiate a long term agreement for the future. Sailed from Britain 22nd Sept and arrived via Archangel on 28th.

The 1st Lend Lease protocol came out of those meetings and covered the Anglo-American supply commitments from Oct 1941 to June 1942. The first US supplies were delivered as part of convoy PQ6 which arrived at Murmansk on 20 Dec 1941.

British aid was able to delivered sooner as a Soviet liaison mission arrived in autumn 1941. The first convoy, Dervish, sailed on 21 Aug and arrived at Archangel on 31st Aug.

The route via the Persian Gulf had to await the Anglo-Soviet invasion of Iran which took place 25-31 Aug 1941. But a Tripartite Alliance was not signed until Jan 1942. The main delivery route was the single rail line from the head of the Persian Gulf to Russia. By 1943 some 30,000 US personnel were in Iran supporting the delivery of Lend Lease supplies.
 
In relation to the timing of the first US Lend Lease aid to the USSR, the timescale looked like this:-

Late July 1941 Harry Hopkins, Roosevelt's "Special Assistant" on Lend Lease dispatched to Moscow to find out what the Soviets wanted. He returned via London and discussions with Churchill on the Prince of Wales en route to the conference with Roosevelt at Placentia Bay in Aug.

Outcome of that conference was that Averell Harriman (US Lend Lease representative in London) and Lord Beaverbrook (British Minister of Supply) were sent to Moscow to negotiate a long term agreement for the future. Sailed from Britain 22nd Sept and arrived via Archangel on 28th.

The 1st Lend Lease protocol came out of those meetings and covered the Anglo-American supply commitments from Oct 1941 to June 1942. The first US supplies were delivered as part of convoy PQ6 which arrived at Murmansk on 20 Dec 1941.

British aid was able to delivered sooner as a Soviet liaison mission arrived in autumn 1941. The first convoy, Dervish, sailed on 21 Aug and arrived at Archangel on 31st Aug.

The route via the Persian Gulf had to await the Anglo-Soviet invasion of Iran which took place 25-31 Aug 1941. But a Tripartite Alliance was not signed until Jan 1942. The main delivery route was the single rail line from the head of the Persian Gulf to Russia. By 1943 some 30,000 US personnel were in Iran supporting the delivery of Lend Lease supplies.
Going from memory, the majority of US supplies to the Soviet Union went via the Pacific route. This was made possible due to Japan/USSR were not at war until 1945. There were some limitations, but I'm not where I can look them up.
 
it looks like the early use of P-39 by the Soviets consisted of two regiments (somewhere between a squadron and a fighter group in size, in US terms) in 1942 and then 3 more plus some smaller units in 1943, after two distinct workups in two separate training / transition units, the 22nd and 25th ZAP. The 22nd up north close to the border with Finland, and the 25th down in the South, feeding units into the fighting in the Kuban area, between the Black Sea and Sea of Azov area. Roughly 600-700 km south-west of Stalingrad.
 
I was talking about over-boosting.
An over-boosted V-1710 or the Merlin will still be running at 3000 rpm; an over-boosted BMW 801 or R-2800-21 or -8W will still be running at 2700 rpm.
The Allison usually had an rpm override switch. Flip it up and the rpm went up by 200 for each switch movement. That switch is on every P-40 instrument panel.

So, if you are being chased by an opponent who is static or slightly gaining on you, most pilots would give the override switch a flick or two and go to 3,200 or 3,400 rpm to save their own lives. Since the Allison was designed for 4,000 rpm and limited to 3,000 by factory recommendation, the engine didn't suffer any harm at the higher rpm. I'm not too sure if the propellers were designed for 3,400 rpm and throwing a blade would certainly ruin the flight home. But both the Merlin and Allison could be turn to at least 3,600 rpm without suffering much if any actual engine damage.

The Merin was slightly more susceptible to rpm damage than the Allison, but not by much ... the Allison rods were stronger, but the Merlin's 2-stage supercharger guaranteed its place in history as a superb engine whereas the very few faults, all subsequently corrected, in the early Allisons virtually guaranteed their place in history as a bit flawed. In point of fact, the Merlin was usually first to a new power level, but the Allison was right behind and, by the end of the war, there was little to choose, power-wise, between them. Just to set the record straight, Merlin rods are perfectly good at stock power levels and don't start failing until 2,400 hp or so. Allison rods are good for 3,600 hp+. Neither engine made those kinds of power in military service, so either set of rods was good for WWII combat flight.

Unfortunately, right when the Allison was starting to produce 2,100 hp+ on test stands, the customer was throwing money at jet engines and not at new piston engine development, so these powerhouses never flew much less got produced in any numbers. The best of the Allisons were one-off test stand mules. Such is history anyway. I don't think any stock Allison made more than about 1,750 hp in service, and those were in P-63s that didn't get into combat in U.S. service.

You could get 1,700 hp from a V-1710-99 (P-40N), but not at 57" and 3,000 rpm. You needed 75" and 3,200/3,400 rpm to get the power. That WAS done in service, just not widely and generally not with "permission" from the unit. I've spoken with 3 - 4 people who said they pushed wartime P-40s that hard when the chips were on the line. They all said other people did it, too, when it was indicated. A light P-40 pushed that hard climbed pretty well at 170 mph, according to people who were there and did it.

Edit:
Also according to owners, one engine you can't increase rpm on much is the Bristol Centaurus. It is very reliable at stock power and rpm levels. You CAN increase boost, but as little as 200 rpm increase can precipitate a failure. It can make more power, but not by turning it faster ... just by increasing boost.

The Wright R-3350 can spin faster and do OK, but these are later, post-WWII R-3350s, not the engines that were flying in WWII, which were NOT very reliable when pushed. Heck, they weren't all THAT reliable when operated in cruise!

The R-2800 can do all sorts of crazy boosting and run just fine. But, again, it depends on the R-2800 engine series. Later engines were better than earlier ones, and the 2,800 hp version was never all that reliable when pushed to 2,800 hp. But 2,500 hp? All day long, no problem! ... as long as you watch the temps.
 
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