Ki-84 Hayate ("Frank")

[f101]

Ki-84

 

SL HP ~2000hp

Wing Area 226 ft2

SL Speed 360-365mph

 

P-51

25lbs boost

 

SL HP ~2000hp

Wing Area 236 ft2

SL Speed 380-405mph

 

Spit XIV

21 lbs boost

 

SL HP ~2000hp

Wing Area 244 ft2

SL Speed 365-370mph

 

You can safely assume that Ki-84 had worst aerodynamic. It markedly slower than P-51 but had same power and smaller wing. It had same speed as Spit XIV but wing area of the Ki-84 smaller. At altitude things become different because Ki-84 had more power than P-51 but its close to Spit XIV at 18lbs boost. Id say Ki-84 w. 45-21 engine could fly at 410-420mph or so at altitude (~20K ft).

Edited October 5, 2005 by f101

[GregShaw]

Oops.

 

Most Allison V-1710s had a WEP rating of 200-250 hp over their military power rating so 1,825 hp seems a little high but was probably somewhere between 1,700 & 1,800 hp.

It was basically the same core engine that the P-63 used, which was rated about 1825 hp WEP(H20). My copy of "Vee's for Victory" is in storage for another couple days, but I'm pretty sure it was approx the same as the P-63's engine.

The P-38L V-1710-111/113s were rated at 1,475 hp at military power & 1,725 hp at WEP (many sources simply slpit the difference & rate then at 1,600 hp)

Officially they were rated at the same 1425 hp 54" Hg mil and 1600 hp 60" Hg WEP as the F-17 engines on the P-38H/J, all at 3000 rpm. P-38L ratings do not make a lot of sense, I have seen them listed at 66" Hg 3200 rpm 1725 hp, which cannot be correct and would be closer to 1850 hp at that setting. Best guess is they appear to have been boosted to 56" Hg 1475 hp mil, and 65" Hg 1725 hp WEP while staying at 3000 rpm.

That still puts the XP-40Q in the same power-to-weight range as the Spitfire XII but still significantly less than the Spitfire Mk XIV - neither of which could reach 20,000 ft in less than 6 min.

The Spitfire XII's Griffon was a single-stage/two-speed engine that crapped out at fairly low altitudes. The two-stage/variable-speed Allison had a much smoother power/altitude curve and put out higher power at altitude than the larger Griffon in the Spitfire XII could manage. I've already shown the XP-40Q had about the same hp/weight ratio as a Spitfire XIV depending on what the Spitfire's Griffon was rated at at the time, ie +18 or +21 psi. And it is arguable how common +21 psi was as a service rating, so the XP-40Q is about the same hp/weight at peak power as a typical Spitfire XIV at peak power.

 

That brings up another point, you CANNOT make a valid comparion based on a single point in an engines power/altitude curve. So saying the Spitfire had a 2350 hp engine while the XP-40Q had a 1825 hp engine doesn't really say much unless you know what the rest of the power/altitude curve looks like.

The P-51D could reach 20,000 ft in about 7min.  The XP-40Q was rejected because is did not significantly improve on the performance of existing aircraft.

The P-51D had about the worst power/weight ratio of ANY late war western fighter and was a indifferent climber at best.

If the XP-40Q could reach 20,000 ft in less than 5 min it would have definately been produced.

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The XP-40Q wasn't produced because the range sucked, the P-47M and P-51H were entering service and the XP-80 was going to render all the piston fighters obsolete soon. Besides which, Curtis had dropped the ball with the P-46 and P-60 programs, were building piss poor versions of other manufacturer's aircraft and there was already some political murmuring about how long the P-40 had been kept in production.

 

The USAAF simply didn't need a fast climbing interceptor, they need range, range and more range, not to mention RANGE. The XP-40Q simply didn't fit their needs, and couldn't match the overall performance of the current P-38, P-47 and P-51 models.

 

Greg Shaw

[Guest pfcem]

It was basically the same core engine that the P-63 used, which was rated about 1825 hp WEP(H20). My copy of "Vee's for Victory" is in storage for another couple days, but I'm pretty sure it was approx the same as the P-63's engine.

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So the XP-40Q had basically the same engine & weight as the Bell P-63C Kingcobra.

 

The first P-63C production block, designated P-63C-1 (company designation Model 33C-1), differed from the P-63A by being powered by the uprated Allison V-1710-117 engine with a war emergency rating of 1,500 hp (1119 kW) at sea level and 1,800 hp (1343 kW) with water injection. The wingspan was reduced by ten inches to 38 feet 4 inches. Apart from the more powerful engine, the P-63C-1 was basically similar to the P-63A-10.

 

The maximum speed of the P-63C was 410 mph at 25,000 ft (7620 m). An altitude of 25,000 ft (7620 m) could be reached in 8.6 minutes. Service ceiling was 38,600 feet. Weights were 6,800 lbs (3084 kg) empty, 8,800 lbs (3991 kg) gross, and 10,700 lbs (4853 kg) maximum takeoff. Dimensions were wingspan 38 feet 4 inches, length 32 feet 8 inches, height 12 feet 7 inches, and wing area 248 sq ft (23 sq m). Armament consisted of a single 37 mm cannon in the propeller hub, plus four 12.7 mm (0.50 in) machine guns (two in the fuselage and two in underwing gondolas).

 

25,000 ft in 8.6 minutes should equate to 20,000 ft in 5.5-6 min.

 

 

The Spitfire XII's Griffon was a single-stage/two-speed engine that crapped out at fairly low altitudes. The two-stage/variable-speed Allison had a much smoother power/altitude curve and put out higher power at altitude than the larger Griffon in the Spitfire XII could manage. I've already shown the XP-40Q had about the same hp/weight ratio as a Spitfire XIV depending on what the Spitfire's Griffon was rated at at the time, ie +18 or +21 psi. And it is arguable how common +21 psi was as a service rating, so the XP-40Q is about the same hp/weight at peak power as a typical Spitfire XIV at peak power.

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I was just looking for a Spitfire with a similar power-to-weigh ratio to the XP-40Q.

 

Admittedly the Spitfire XII was a dedicated low altitude with a single-stage Griffon. How does that effect is rate of climb at 20,000 ft & lower?

 

The XP-40Q & Spitfire Mk XIV do not have about the same hp/weight at peak power. They weight about the same (normal take-off weight for the Spitfire Mk XIV was less than 9,000 lbs, maximum take-off weight was 10,250 lbs) but the Spitfire Mk XIV has a peak power rating more than 200 hp greater than the XP-40Q.

 

 

That brings up another point, you CANNOT make a valid comparion based on a single point in an engines power/altitude curve. So saying the Spitfire had a 2350 hp engine while the XP-40Q had a 1825 hp engine doesn't really say much unless you know what the rest of the power/altitude curve looks like.

231179[/snapback]

 

Does anybody have these power/altitude curves?

 

How does the V-1710-117 compare with the single-stage Griffon & two-stage Griffon?

[Ol Paint]

I finally managed to dig out my copy of "Vee's for Victory! The Story of the Allison V-1710 Aircraft Engine 1929-1948.

Curtiss XP-40Q

This program began with an early two stage version of the V-1710 fitted into the first XP-40Q.  That engine is believed to have been the V-1710-45(F7R), but has not been confirmed.  In May 1943 Allison was able to make available an improved engine, the V-1710-101(F27R), which was a two-stage engine having the carburetor mouted between the stages.  Curtiss believed that with this engine, "a substantial performance increase in speed and altitude will result."  This improved engine was desired as other airframe manufacturers (notably Bell) had been having difficulties with the early two-stage engines similar to the one then installed.  In addition to the two-stage engine, the XP-40Q had been modernized by giving it a laminar flow wing section and a bubble canopy.

 

The basic engine was an "F" configuration of the V-1710-E11 as developed for the P-63 airplanes, though the various models went through considerable development and incorporation of advanced components.  For example, by November 1943 and engine with the carburetor located between the stages was being flown with the 6.85:1 Auxiliary Stage gears and obtaining 54 inHgA at altitudes up to 30,000ft.  When the 7.23:1 gears, identifying the V-1710-121(F28R), were installed the performance improved to the point that at high-altitude it equaled the performance of the Rolls-Royce RM14SM high performance two-stage Merlin.

 

In January 1944 one of the XP-40Q's was flown to Eglin Field, Florida, for Army tactical and performance tests against other late model Army fighters.  For these critical tests the Auxiliary Stage Supercharger drive ratio was changed to 7.23:1 (making it in effect a V-1710-121(F28R)) with Allison authorizing the modified V-1710-101 to operate with a 3200rpm WER rating of 63 inHgA at sea-level.  A new control schedule for the hydraulic coupling biased the low-level performance of the Aux Stage while giving a greater critical altitude.

 

As the Curtiss Model 87X and the culmination of the XP-40Q program, P-40N-25 AC43-24571 was the third and final XP-40Q.  It featured a bubble canopy and a cut-down aft fuselage deck as had been previously tested on the XP-40N.  The extended nose was to accommodate the engine with its Auxiliary Stage Supercharger.  The modification made for a long and fairly sleek aircraft.  The XP-40Q-2 version, with the clipped wing tips and utilizing water injection, demonstrated a maximum speed of 422mph at 20,500 feet.  In a time-to-climb trial it demonstrated a climb to 20,000 feet in 4.8 minutes.  This made it the fastest and highest flying of all the P-40's...

 

--SNIP--

 

XP-40Q-2...With the two-stage V-1710-101 engine rated for WER power, and a weight of 8,363 pounds, the airplane could climb at 3,800 ft/min at 13,000 feet, reaching 21,000 feet in six minutes...

 

--SNIP--

 

XP-40Q-3  P-40N-25 AC43-24571 was fitted out like the Xp-40Q-2 but incorporated increased capacity brakes, a flat bullet-proof windshield, a four bladed propeller and was fitted with the Allison V-1710-121(F28R).  This engine with its auxiliary stage supercharger developed 1425bhp at 3000 rpm for takeoff, used the 12-counterweight crankshaft that allowed War Emergency Power of 1700bhp at 26,000 feet to be developed at 3200 rpm.  This aircraft was the only XP-40Q delivered to the AAF as such, though not until early 1945.  The others retained their original P-40K delivery status.

 

The key to the climb performance is that the engine configuration permits the aircraft to maintain climb rates as altitude increases, something that the less-advanced supercharger of the Ki-84 could not do. So, while the Ki-84 may have had excellent climb at low altitudes, this performance would be dropping off as the density of the air decreased.

 

Another data point:

On June 30, 1944 the AAF officially ordered two XP-51J (AF44-76027/28) "light weight" Mustang aircraft as proposed by North American in their Model Specification, dated January 1, 1944.  The primary purpose of the aircraft was to produce a lightweight fighter with exceptional high speed, maneuverability, and performance characteristics, with priority being given to rate of climb and maneuverability.  In the process, they were to test the new Allison V-1710-119 (F32R) two-stage aftercooled engine.  Allison put the first F32R on test in July 1944.  First flight of the aircraft was not until April 23, 1945, piloted by North American's Joe Barton.

 

The aircraft was different from the Merlin-powered XP-51F only from the firewall forward.  The F-32R developed 1500bhp for takeoff and 1720 bhp at War Emergency conditions up to 20,700 feet.  At sea-level, 2100 bhp was available.  At 27,400 feet, the aircraft was to be capable of 491 mph, be able to climb to 20,000 feet in five minutes (6,600 ft/min using 150 Grade fuel) and have a 43,700 foot service ceiling.

But this is all BS, while anything to do with the Ki-84 is gospel...

 

Douglas

 

[Edited for Steeleism--"constrol" should've been "control."]

Edited October 9, 2005 by Ol Paint

[Guest pfcem]

I finally managed to dig out my copy of "Vee's for Victory!  The Story of the Allison V-1710 Aircraft Engine 1929-1948.

232735[/snapback]

 

 

Your souce contradicts itself as to the climbing capability of the XP-40Q-2.

 

The XP-40Q-2 version, with the clipped wing tips and utilizing water injection, demonstrated a maximum speed of 422mph at 20,500 feet.  In a time-to-climb trial it demonstrated a climb to 20,000 feet in 4.8 minutes.

 

XP-40Q-2...With the two-stage V-1710-101 engine rated for WER power, and a weight of 8,363 pounds, the airplane could climb at 3,800 ft/min at 13,000 feet, reaching 21,000 feet in six minutes...

 

According to that, the XP-40Q-2 could average 4167 ft/min up to 20,000 ft but could only manage 833 ft/min from 20,000 to 21,000 ft. Coincidently the 21,000 ft in 6 min is about what one would expect given my source indicating 25,000 ft in 8.6 min. That would translate to 1042 ft/min from 20,000 to 25,000 ft if the 4.8 min to 20,000 ft were correct. It is also pretty much impossible to reach 20,000 ft in 4.8 min when climbing 3,800 ft/min at 13,000 feet.

[Ol Paint]

Your souce contradicts itself as to the climbing capability of the XP-40Q-2.

According to that, the XP-40Q-2 could average 4167 ft/min up to 20,000 ft but could only manage 833 ft/min from 20,000 to 21,000 ft.  Coincidently the 21,000 ft in 6 min is about what one would expect given my source indicating 25,000 ft in 8.6 min.  That would translate to 1042 ft/min from 20,000 to 25,000 ft if the 4.8 min to 20,000 ft were correct.  It is also pretty much impossible to reach 20,000 ft in 4.8 min when climbing 3,800 ft/min at 13,000 feet.

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No, it doesn't. Different engine models in the same airframe (or an upgrade of the -101 to -121 specs, if you prefer). Still, I am interested in how you can take issue with these figures, published for "tests" and still take umbrage when the pedigree of Ki-84 numbers is questioned. Do you really not see the hypocrisy of your stance?

 

Douglas

[GregShaw]

The XP-40Q first flew with the F-27 Allison, rated at 1500 hp WEP on 60 in Hg @ about 6000 ft, with the aux stage blower at max slip. It could also do 1150 hp mil up to about 22,000, which would put 60 in WEP available up to about 18,000 ft and 1350 hp min slip.

 

It was later fitted with the F-28, rated at 75 in Hg and 1700 hp up to 26,000 ft, using water injection. The F-28 was similar to the F-27, but had a higher gear ratio on the aux stage that greatly increased the pressure ratio of the blower system. It also was fitted with ADI (water injection) that allowed it to use higher manifold pressures without fear of detonation due to compression heating of the charge air. That is the engine that gave it the 4.8 minutes to 20,000 ft performance that you cannot seem to accept. The P-63 was fitted with a similar E Series Allison, but rated at 1800 hp at 24,000 ft, it likewise could manage 20,000 ft in about 4.8-5.0 minutes.

 

*Going off of memory on some of the engine ratings, I found my "Vee's for Victory" while moving in last night, but don't have internet access setup at my new condo yet.

 

Greg Shaw

[Guest pfcem]

Ol Paint & GregShaw

 

The problem I have with the contension that the XP-40Q could reach 20,000 ft in 4.8 min is that the only WWII (or shortly after WWII) fighters that I can find any credible evidence of being able to reach 20,000 ft in under 6 min all had more than 2,000 hp (or weighed less that 7,000 lbs). All of the WWII (or shortly after WWII) fighters that I can find with similar power (1650-1,800 HP) & weight (8,000-9,000 lbs) indicate being able to reach 20,000 ft in 6-7 min.

 

I have not seen any V-1710 prior to 1947-48 with a WEP rating of over 1800 hp.

 

***

 

Specificaion of the Bell P-63C Kingcobra (all sources I have seen tend to agree with the following)

 

Powerplant: One Allison V-1710-117 engine with a war emergency rating of 1500 hp at sea level and 1800 hp with water injection.

 

Performance: maximum speed 410 mph at 25,000 feet. An altitude of 25,000 feet could be reached in 8.6 minutes. Service ceiling was 38,600 feet.

 

Weights: 6800 pounds empty, 8800 pounds gross, and 10,700 pounds maximum takeoff.

 

Dimensions: Wingspan 38 feet 4 inches, length 32 feet 8 inches, height 12 feet 7 inches, and wing area 248 square feet.

 

Armament: One 37-mm cannon in the propeller hub, plus four 0.50-inch machine guns, two in the fuselage and two in underwing gondolas.

 

***

 

When credible performance data about an aircraft is lacking, the only way to get a realisticly idea of what that performance might be is to compare it to similar aircraft. This is what I have done & it indicates that the Frank was capable of 420+ mph (not 388-392 mph) & that the XP-40Q was capable of reaching 20,000 ft in about 6 min (not 4.8 min).

[Ol Paint]

Ol Paint & GregShaw

 

The problem I have with the contension that the XP-40Q could reach 20,000 ft in 4.8 min is that the only WWII (or shortly after WWII) fighters that I can find any credible evidence of being able to reach 20,000 ft in under 6 min all had more than 2,000 hp (or weighed less that 7,000 lbs).  All of the WWII (or shortly after WWII) fighters that I can find with similar power (1650-1,800 HP) & weight (8,000-9,000 lbs) indicate being able to reach 20,000 ft in 6-7 min.

 

I have not seen any V-1710 prior to 1947-48 with a WEP rating of over 1800 hp.

 

***

 

--SNIP--

 

***

 

When credible performance data about an aircraft is lacking, the only way to get a realisticly idea of what that performance might be is to compare it to similar aircraft.  This is what I have done & it indicates that the Frank was capable of 420+ mph (not 388-392 mph) & that the XP-40Q was capable of reaching 20,000 ft in about 6 min (not 4.8 min).

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V-1710-129 had a WER rating of 1900 bhp in 1945. The -93 had a WER rating of 1825 bhp in late 1943. The -117 had a WER of 1800 bhp. The -127 had a WER of 2430 bhp at 18,000 feet and 3090bhp at 28000 at 100 inHgA MAP. In 1944. To be fair, this was a turbo-compound prototype engine...

 

The XP-51J weighed more than 7,000lb (6,030lb empty/7,540lb gross) and had a time to 20,000ft of 5.0 minutes (3.6min in WER--6,600fpm initial rate of climb). Given this type of performance potential from the P-51 airframe, is there any question why the AAF may have been less than impressed by the XP-40Q--or the Ki-84?

 

The point about the "credible" data is exactly what Joe Brennan and others were making. There is, apparently, some question as to whether the Ki-84 achieved 427mph by testing, or by estimate. You are raising the same questions about XP-40Q performance that others have raised about the Ki-84. You claim to be comparing to similar aircraft but then, somehow, a government conspiracy enters the picture because you contend US aircraft couldn't achieve similar performance--in the face of evidence to the contrary. Even using your comparison basis, the XP-40Q and XP-51J are in the same weight class, somewhat less horsepower, yet exceed Ki-84 performance. Why? Two-stage/variable speed supercharging at a minimum. With the acknowledged inferiority of the Ki-84 engine in this area, where is the basis for US conspiracy into performance cover-ups? Again, there is no claim the Ki-84 could not attain 42Xmph under IDEAL conditions. Your contention that it achieved this performance in Japanese wartime service simply doesn't hold water, absent clarification on the performance numbers, nor does it support irrational fears on the part of the US. The US acknowledged then, and current thinking still is, that the Ki-84 was a dangerous aircraft that rectified many of the deficiencies exhibited by previous aircraft. Your contention that the Ki-84 could out-climb, out-run, AND out-maneuver every Allied fighter is apparently not true. Two out of three, maybe, and only in skilled hands. Furthermore, US fighters were probably entering the fight with advantages in energy (higher ceilings and better altitude performance), training, fuel, reliability, maintenance, and likely numbers. Good, yes--but not a world-beater nor inspiring of a 60-year conspiracy.

 

Douglas

[Guest pfcem]

V-1710-129 had a WER rating of 1900 bhp in 1945.  The -93 had a WER rating of 1825 bhp in late 1943.  The -117 had a WER of 1800 bhp.  The -127 had a WER of 2430 bhp at 18,000 feet and 3090bhp at 28000 at 100 inHgA MAP.    In 1944. To be fair, this was a turbo-compound prototype engine...

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I admit that my source materials on the "exotic" late model V-1710 are limited but they still indicat 1,800 hp WEP for the - 93 & -129.

 

The only date I can find mentioned for the XP-63H or V-1710-127 is in 1946-47.

 

 

 

The point about the "credible" data is exactly what Joe Brennan and others were making.  There is, apparently, some question as to whether the Ki-84 achieved 427mph by testing, or by estimate. 

233296[/snapback]

I have already aswered that.

 

 

 

You are raising the same questions about XP-40Q performance that others have raised about the Ki-84.  You claim to be comparing to similar aircraft but then, somehow, a government conspiracy enters the picture because you contend US aircraft couldn't achieve similar performance--in the face of evidence to the contrary. 

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Again, comparing similar aircraft, the Frank is capable of significantly more than the "official" performance data from the 1st prototype but the XP-40Q in only capable of reaching 20,000 ft in about 6 min (not 4.8 min).

 

 

 

Even using your comparison basis, the XP-40Q and XP-51J are in the same weight class, somewhat less horsepower, yet exceed Ki-84 performance.  Why?  Two-stage/variable speed supercharging at a minimum.  With the acknowledged inferiority of the Ki-84 engine in this area, where is the basis for US conspiracy into performance cover-ups?  Again, there is no claim the Ki-84 could not attain 42Xmph under IDEAL conditions.

233296[/snapback]

It has already been stated many times that allied fighters had a decided advantage abouve 25,000 ft but what advantage does a two-stage supercharger have over a single-stage supercharger below 20,000 ft.

 

Where is all this talk of a conspiracy coming from?

 

I have made no mention of any conspiracy.

 

 

 

Your contention that it achieved this performance in Japanese wartime service simply doesn't hold water, absent clarification on the performance numbers, nor does it support irrational fears on the part of the US.  The US acknowledged then, and current thinking still is, that the Ki-84 was a dangerous aircraft that rectified many of the deficiencies exhibited by previous aircraft. 

233296[/snapback]

Again, a well maintained Franks with a good pilot was hard to come by for the Japaese in 1945. But not impossible.

 

How could the Frank have been "a dangerous aircraft that rectified many of the deficiencies exhibited by previous aircraft" if only capable of less than 400 mph. Previous Japanese fighters could already out climb & out maneuver most allied fighters in many situations below 25,000 ft.

 

 

 

Your contention that the Ki-84 could out-climb, out-run, AND out-maneuver every Allied fighter is apparently not true.  Two out of three, maybe, and only in skilled hands. 

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Your are misquoting me, What I said was:

 

Both wartime reports & postwar flight tests (whether you believe them or not) clearly state that when a well-maintained Frank was flown by a good pilot, it could out climb, out turn, & out run any US fighter at 20,000ft or below.

Furthermore, US fighters were probably entering the fight with advantages in energy (higher ceilings and better altitude performance), training, fuel, reliability, maintenance, and likely numbers.  Good, yes--but not a world-beater nor inspiring of a 60-year conspiracy.

233296[/snapback]

It has already been stated many times that allied fighters had a decided advantage abouve 25,000 ft but what advantage does a two-stage supercharger have over a single-stage supercharger below 20,000 ft.

 

Where is all this talk of a conspiracy coming from?

 

I have made no mention of any conspiracy.

[Ol Paint]

Conspiracies? Here you go:

--SNIP--

My guess is that the reason why nobody seems to be able to confirm the actual speed the Frank obtained during US fight tests in 1946 is because it turned out to be even faster (with US fuel) then they thought it would be and did not want to admit to the public how fast it really was.

--SNIP--

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--SNIP--

Yes a 420mph Japanese fighter would not be a major concern for the US in 1946 but admitting that in 1945 a Japanese fighter was capable of speeds similar to the F4U-4 (for example) would be.

 

Name a 1945 US aircraft that could turn or climb with a Frank.  The only one I can think of that possibly could would be the F8F Bearcat but we had very few of them & they were all on the US west coast, not in the Japanese theater.

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--SNIP--

The US conducted flight tests on numberious Japanese aircraft in 1946.  Prior to that we actually new very little about them.  In 1946 the US government was unwilling to admit (to the general puplic) that Japan was capable of producing a fighter equal to or superior to the planes we were flying at the time.

--SNIP--

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A two-stage supercharger is going to have a wider operating range and the capability to provide higher levels of boost at all altitudes, whereas the single-stage supercharger engine performance is going to fall off steadily as altitude increases above the critical altitude. For instance, the P-51 two-speed/two-stage supercharger operated in low-speed/single-stage up to ~8,500ft, kicked into high speed/single-stage between there and 13,000ft, then went to low-speed/two-stage operation from there to 17,000ft, then high-speed/two-stage above this altitude. (All altitudes are fictional--I don’t remember what the actual numbers are.) At each speed change/stage change, the engine output basically jumps back up to the sea-level max power, while the single stage engine is going to have much greater performance drops between changes in supercharger operating conditions. [2nd Edit: Assuming a two-speed/single-stage supercharger--if it was a single-speed, performance is just going to steadily drop off above the critical altitude.] Unless the Ki-84 engine was significantly overboosted, I find it unlikely that the engine was going to maintain sea-level power up to 20,000ft with a single-stage supercharger.

 

Again, you are rejecting information because it "doesn't feel right," while making wild claims about any doubts raised regarding the exact speeds the Ki-84 could achieve under ideal conditions. You are on the record stating that the Ki-84 was achieving 420-430mph in wartime service. Fine, but the body of evidence suggests that 390 was more likely due to maintenance issues, lack of US 100/130 fuel, & other factors, although I am willing to be wrong should hard evidence be produced that the aircraft was operating in Japanese service under ideal conditions.

 

[Edit: How could it be dangerous without exhibiting superior speed? Because it appears to have eliminated/reduced the high-speed maneuverability issues of earlier aircraft while being of comparable (but not absolutely superior) performance across a range of categories. Again, a good airplane, but not a world-beater in 1944-1945.]

 

Douglas

Edited October 10, 2005 by Ol Paint

[Guest pfcem]

Conspiracies?  Here you go:

A two-stage supercharger is going to have a wider operating range and the capability to provide higher levels of boost at all altitudes, whereas the single-stage supercharger engine performance is going to fall off steadily as altitude increases above the critical altitude.  For instance, the P-51 two-speed/two-stage supercharger operated in low-speed/single-stage up to ~8,500ft, kicked into high speed/single-stage between there and 13,000ft, then went to low-speed/two-stage operation from there to 17,000ft, then high-speed/two-stage above this altitude. (All altitudes are fictional--I don’t remember what the actual numbers are.)  At each speed change/stage change, the engine output basically jumps back up to the sea-level max power, while the single stage engine is going to have much greater performance drops between changes in supercharger operating conditions.  [2nd Edit:  Assuming a two-speed/single-stage supercharger--if it was a single-speed, performance is just going to steadily drop off above the critical altitude.]  Unless the Ki-84 engine was significantly overboosted, I find it unlikely that the engine was going to maintain sea-level power up to 20,000ft with a single-stage supercharger.

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I get all that but my understanding was that the altitudes were much higher.

 

IIRC, most non-supercharged WWII fighter engines performed quite well up to 10, 000 ft before supercharged engines gained a significant advantage & that single-stage supercharged WWII fighter engines performed quite well up to 20,000 ft before two-stage supercharged engines gained a significant advantage.

 

 

 

Again, you are rejecting information because it "doesn't feel right," while making wild claims about any doubts raised regarding the exact speeds the Ki-84 could achieve under ideal conditions. 

233372[/snapback]

No & for the 4th or 5th time now. Comparing similar aircraft, the Frank is capable of significantly more than the "official" performance data from the 1st prototype but the XP-40Q in only capable of reaching 20,000 ft in about 6 min (not 4.8 min).

 

 

 

You are on the record stating that the Ki-84 was achieving 420-430mph in wartime service.  Fine, but the body of evidence suggests that 390 was more likely due to maintenance issues, lack of US 100/130 fuel, & other factors, although I am willing to be wrong should hard evidence be produced that the aircraft was operating in Japanese service under ideal conditions.

233372[/snapback]

No, I contend that the Frank was capable of 420-430 mph.

 

There is no evidence that suggests that 390 mph was more likely.

 

Again, a well maintained Frank with a good pilot was hard to come by for the Japaese in 1945. But not impossible.

 

 

 

[Edit:  How could it be dangerous without exhibiting superior speed?  Because it appears to have eliminated/reduced the high-speed maneuverability issues of earlier aircraft while being of comparable (but not absolutely superior) performance across a range of categories.  Again, a good airplane, but not a world-beater in 1944-1945.]

233372[/snapback]

Make up your mind.

 

Was the Frank only capable of the performance indicated or was it capable of comparable performance (I assume you mean comparable to allied fighters which is what I have been saying all along) across a range of categories?

[Pachy]

-The Bloch 157, built by germans from the pieces made by frenchs in 1940, with a a radial of 1500HP archieved a 710 KMH maximum speed (believe that the windspeed was mounted wrong, like you want)

229511[/snapback]

The MB.157 was built and flight-tested by France... That speed claim is supposed to be from French testing. OTOH the SNCA-SO was famous for having cheated in speed tests in 1938 so that the MB.150 project would not be cancelled!

[Ol Paint]

Since you have proffered the P-63, I’ll raise you WER ratings for the aircraft. From “Vee’s for Victory” tables:

P-63A-8

Empty Weight: 6,531.9lb

Gross Weight: 8,213.2lb

Engine: V-1710-93

Mil Power: 1,150bhp

WER Power: 1,390bhp

Time to climb, Mil Power: 6.8min/22,400ft

Time to 20,000ft, WER: 4.8min

 

P-63A-10

Empty Weight: 6,693.7lb

Gross Weight: 8,264.7lb

Engine: V-1710-93

Mil Power: 1,150bhp

WER Power: 1,390bhp

Time to climb, Mil Power: 7.2min/22,400ft

Time to 20,000ft, WER: 4.9min

 

P-63C-1

Empty Weight: 6,798.5lb

Gross Weight: 8,448.4lb

Engine: V-1710-117

Mil Power: 1,100bhp

WER Power: 1,440bhp

Time to climb, Mil Power: 8.8min/25,000ft

Time to 20,000ft, WER: 5.0min

 

P-63C-5

Empty Weight: 6,855.7lb

Gross Weight: 8,640.2lb

Engine: V-1710-117

Mil Power: 1,100bhp

WER Power: 1,440bhp

Time to climb, Mil Power: 8.6min/25,000ft

Time to 20,000ft, WER: 5.0min

 

P-63D-1

Empty Weight: 7,076.0lb

Gross Weight: 9,053.7lb

Engine: V-1710-109

Mil Power: 1,100bhp

WER Power: 1,300bhp

Time to climb, Mil Power: 11.2min/28,000ft

Time to 20,000ft, WER: 4.4min

 

P-63E-1

Empty Weight: 7,088.1lb

Gross Weight: 8,897.3lb

Engine: V-1710-109

Mil Power: 1,100bhp

WER Power: 1,340bhp

Time to climb, Mil Power: 8.7min/28,000ft

Time to 20,000ft, WER: 4.5min

 

P-63F-1

Empty Weight: 7,111.9lb

Gross Weight: 8,911.8lb

Engine: V-1710-133

Mil Power: 1,150bhp

WER Power: 2,200bhp

Time to climb, Mil Power: 7.7min/28,000ft

Time to 20,000ft, WER: 3.0min

 

Any retractions about XP-40Q performance being “impossible,” yet? I do notice that you have tried to blame the conspiracy on the Japanese, too.

 

Being dangerous is not mutually exclusive of inferior performance. Nor is the term “comparable” the same thing as “identical”--it means “close to” rather than “markedly inferior/superior.” It is fairly well-established that the Ki-84 could not out-run Allied fighters in actual combat situations--JOE BRENNAN covered that. He also provided documentation that the 427mph figure may have been an estimate, rather than a flight test value. However, below 20,000ft, the Ki-84 does not appear to have grossly inferior speed in Japanese service and may have been faster than some Allied aircraft at some altitudes. On US high-octane with exacting maintenance, it may have even been capable of 420-430mph at 20,000ft. Under service conditions, however, it apparently suffered from low-octane fuel & unreliable engine performance. In 1944-1945, US warplanes were going to have a rather noticeable edge in performance and, by late 1945, the Ki-84 would be completely outclassed by late-model P-51/F2G/F8F/F7F/Seafire/Sea Fury/etc.

 

We don’t have instantaneous & sustained turn rate information, but we do know that the Ki-84 was considered to be a good dogfighter. Possible advantage to the Ki-84 against Allied fighters at the same altitude/energy level.

 

We also don’t have dive acceleration numbers, but it is probable that Allied fighters maintained their superiority here, although the edge may have been cut somewhat. Since the Allied fighters have a definite altitude superiority (40,000+ vs. 34,000ft) and engine performance, the high-altitude fight goes to the Allies, hands down, and there is a good possibility that the Allied fighters would be entering many dogfights with the energy advantage.

 

In 1945, any US pilot that got into a low-speed/low-altitude turning fight with a A6M (assuming good pilots) is likely to be in trouble. Put another way, the Me262 was clearly faster & faster-climbing than Allied fighters, but that didn’t mean that the Allied fighters weren’t still dangerous in certain situations. You are too quick to hunt a fight, here, especially since you earlier stated that speed wasn’t everything (“A dogfight isn’t a drag-race” were your words, as I recall). I say again, as a package, the Ki-84 was a dangerous opponent, but didn’t offer superiority over Allied fighters in 1944/1945 and I’ll go further and state that the production models would be out-classed by Allied production fighters in late 1945.

 

Douglas

[Guest pfcem]

TEXT DELIBERATELY DELETED TO SAVE ON SPACE.

 

233743[/snapback]

Please do not get me wrong, the P-39/P-63 is one of my favorite WWII fighters. Unfortunately they suffered from a bad rap becuase the US would not allow supercharged engines for them to be exported early in the war & would undoubtably have been much more popular had Japan or Germany had signifiant numbers of heavy bombers (that 37mm cannon would have been the best weapon the allies had to take down enemy heavy bombers).

 

Your source for time to climb does not coinside with the sources I have scene.

 

The most common I have seen is a rate of climb of 4,000 ft/min which would make those times impossible.

 

If those times are correct, then the time for virtually every other aircraft is at least 1.5 min too long. The only explination would be that they are all rate of climb/time to altitude numbers at military power & we would have to subtract ~1.5-2 min form all their times to compare them properly.

 

The Ha-45 model 21 was rated at 1,990 hp on Japanese "low octaine fuel" & so its performance during wartime would not be degraded on that assumption. (I also assume that number, like most, is the engine's military power rating but I would not expect WEP ratings for japanese engines to increase as much as those of most allied engines)

 

There are reports from both Allied & captured Japanese pilots of Franks out-running allied fighters (admittadly they are all below 25,000 ft IIRC).

 

With exception to the Hellcat, no allied fighter in the last year of the war would have had any problem with a "~390 mph" Japanese fighter. That "~390 mph" is grossly inferior to most late war allied fighters.

 

How many time to I have to say this.

 

A well maintained Frank with a good pilot was hard to come by for the Japaese in 1945. But not impossible. Unreliable mean that it did not always perform at its best, not that it never did. The Ha-45 was a complex engine & not every Japanese mechanic was capable of maintaining it properly but some were.

 

By late 1945, Japan would have likely been flying Frank models with 2,500 hp two-stage supercharged engines which were already in deveopement before the end of the war.

 

True, I said speed is not everything but a speed difference of 30-50 mph (which is what allied fighters would have had if the Frank could only do "~390 mph") is HUGE & would have pretty much rendered any other advantage the Frank had irrelivent as allied fighters could simply "fly away" & choose only to engage when they had a decided advantage. There would also be no reports of Franks out-running allied fighters but there are.

 

Make up your mind, was the Frank only capable of "~390 mph" in Japanese service or "below 20,000ft, the Ki-84 does not appear to have grossly inferior speed in Japanese service and may have been faster than some Allied aircraft at some altitudes", because it simply can not be both.

 

I would think that the Frank's comparatively lower weight would work against it in dive acceleration compared to allied fighters but not necessarily in terminal dive speed. I certainly doubt that the Frank could dive with a P-38 or P-47 (no WWII fighter that I know of could).

 

Just because most allied fighters had superior performance above 25,000-30,000 ft, does not mean that they always had a height advantage.

 

My whole point in all of this has been that at ~25,000 ft or below, the Frank was not that much slower than most allied fighters (even faster than some in some circumstances) & I doubt that anyone would contend that it could not out-maneuver most (if not all) allied fighters given that it was intended to maintain the maneuverability of the Ki-43 Hayabusa (Oscar) - which was said to "out-maneuver any aircraft ever ranged against it".

Edited October 12, 2005 by pfcem

[MiloMorai]

quote: Unfortunately they suffered from a bad rap becuase the US would not allow supercharged engines for them to be exported early in the war

 

All Allison V-1710 engines had superchargers. What was removed from the P-39 was the turbocharger and this was removed even before the a/c went into production. The XP-39B had no turbocharger.

 

The a/c that had the turbochargers removed was the P-38.

[hojutsuka]

Make up your mind, was the Frank only capable of "~390 mph" in Japanese service or "below 20,000ft, the Ki-84 does not appear to have grossly inferior speed in Japanese service and may have been faster than some Allied aircraft at some altitudes", because it simply can not be both.

234013[/snapback]

"pfcem", you seem to totally ignore the fact that an airplane has a different maximum speed at different altitudes.

 

Yes, most US fighters were capable of over 400mph by 1944. But at what altitude? A P-51D is usually said to be capable of 437mph. Less often is it mentioned that this speed is measured at 25,000 feet. If you go down to 5,000 feet, the P-51D only does 395mph. At sea level, it would typically be slower still.

 

The P-47D is capable of 426mph at 30,000 feet, but only 363mph at 5,000 feet.

 

The F6F-3 Hellcat is rated at 376mph at 22,800 feet, but only 324mph at sea level.

 

So it is entirely possible for a Ki-84 to be only capable of ~390mph at altitude (say 20,000 feet), but still be almost as fast or faster than many Allied aircraft at low altitudes like sea level to 5,000 feet.

 

In general, air resistance goes down with air pressure, so if the engine can produce the same power at all altitudes (as is the case with a rocket engine), the airplane will fly fastest at its maximum altitude. However, most aircraft engines use ambient air for combustion, which means that power output declines with higher altitude and lower air pressure. At exactly what altitude an airplane flies the fastest depends therefore on the design of the airplane and the characteristics of its engine. Superchargers and turbo-superchargers can compress the air before it enters the engine proper, so they can help the engine maintain its power at higher altitudes.* But superchargers and turbo-superchargers add weight (and take power to run in case of a supercharger), so they can actually reduce performance at lower altitudes while enhancing it at higher altitudes.

 

In World War II, US and British had superior materials and supercharger technology, so their engines tended to maintain their power output to higher altitudes than the Japanese (or German**) engines. So late-war British and American aircraft tended to have their best performance at higher altitudes (say 25,000 - 30,000 feet), where the lower air resistance allowed them to reach their exceptional maximum speeds.*** In contrast, most Japanese fighters had difficulty in maintaining formation above 30,000 feet, and their maximum speeds were reached at lower altitudes where higher air density kept them from equaling US fighters' figures. However, at low altitudes, the US advantage in supercharger/turbo-supercharger technology became less important, and the performance gap between US fighters and Japanese fighters became less evident.

 

A well maintained Frank with a good pilot was hard to come by for the Japaese in 1945. But not impossible. Unreliable mean that it did not always perform at its best, not that it never did. The Ha-45 was a complex engine & not every Japanese mechanic was capable of maintaining it properly but some were.

234013[/snapback]

By 1944, all Japanese engines and aircraft built were suffering from inferior material and insufficiently skilled manufacturing force. When your pistons have excessive clearance, when your valve timings are off because of a badly machined camshaft, when you don't dare open the throttle fully because your valves made of inferior material will burn out, it doesn't matter how good your mechanic is, you are not going to get the designed power.

 

Hojutsuka

 

* See post #89 on this thread for Ol Paint's more detailed explanation of supercharging.

 

** The Germans got higher performance at high altitudes by using GM1 (nitrous oxide injection). However, this could only be used for limited periods of time, and had a substantial weight penalty for the nitrous oxide and its pressurized container.

 

*** Naval aircraft were an exception. Because ships were moving targets that could only be hit from lower altitudes (at least until guided weapons came along late in WW II), naval aircraft were normally designed for low altitude combat.

[Guest pfcem]

"pfcem", you seem to totally ignore the fact that an airplane has a different maximum speed at different altitudes.

 

Yes, most US fighters were capable of over 400mph by 1944.  But at what altitude?  A P-51D is usually said to be capable of 437mph.  Less often is it mentioned that this speed is measured at 25,000 feet.  If you go down to 5,000 feet, the P-51D only does 395mph.  At sea level, it would typically be slower still.

 

The P-47D is capable of 426mph at 30,000 feet, but only 363mph at 5,000 feet.

 

The F6F-3 Hellcat is rated at 376mph at 22,800 feet, but only 324mph at sea level.

 

So it is entirely possible for a Ki-84 to be only capable of ~390mph at altitude (say 20,000 feet), but still be almost as fast or faster than many Allied aircraft at low altitudes like sea level to 5,000 feet.

234235[/snapback]

NO I AM NOT & that has been my point.

 

Most allied fighters were faster than the Frank above 25,000 ft, but the Frank was comparable (possibly even faster) below 20,000 ft.

 

The Ha-45 had a single-stage supercharger & should therefor maintain its relative power level compared to allied fighter engines up to ~20,000 ft.

 

I have tried to keep this in mind when concluding that the Frank should have been capable of 420-430 mph at 20,000. Otherwise it would likey have been faster still.

 

 

 

 

In general, air resistance goes down with air pressure, so if the engine can produce the same power at all altitudes (as is the case with a rocket engine), the airplane will fly fastest at its maximum altitude.  However, most aircraft engines use ambient air for combustion, which means that power output declines with higher altitude and lower air pressure.  At exactly what altitude an airplane flies the fastest depends therefore on the design of the airplane and the characteristics of its engine.  Superchargers and turbo-superchargers can compress the air before it enters the engine proper, so they can help the engine maintain its power at higher altitudes.* But superchargers and turbo-superchargers add weight (and take power to run in case of a supercharger), so they can actually reduce performance at lower altitudes while enhancing it at higher altitudes.

 

In World War II, US and British had superior materials and supercharger technology, so their engines tended to maintain their power output to higher altitudes than the Japanese (or German**) engines.  So late-war British and American aircraft tended to have their best performance at higher altitudes (say 25,000 - 30,000 feet), where the lower air resistance allowed them to reach their exceptional maximum speeds.*** In contrast, most Japanese fighters had difficulty in maintaining formation above 30,000 feet, and their maximum speeds were reached at lower altitudes where higher air density kept them from equaling US fighters' figures.  However, at low altitudes, the US advantage in supercharger/turbo-supercharger technology became less important, and the performance gap between US fighters and Japanese fighters became less evident.

234235[/snapback]

I know how superchagers/supercharchers/nitrous oxide injection/water-methonal injection work to increase/maintain power at higher altitudes. Above 25,000 ft, allied two-stage supercharged engines had a significant power advantage over Japanese single-stage engines. That is why I have always stated that allied fighters had the advantage over the Frank above 25,000 ft but below 20,000 ft they did not.

 

 

 

By 1944, all Japanese engines and aircraft built were suffering from inferior material and insufficiently skilled manufacturing force. 

234235[/snapback]

That is not what I have read.

[hojutsuka]

By 1944, all Japanese engines and aircraft built were suffering from inferior material and insufficiently skilled manufacturing force.

234294[/snapback]

That is not what I have read.

234294[/snapback]

OK. Provide me with your reference where you read it, and I'll try to check it out.

 

Hojutsuka

[Guest pfcem]

OK.  Provide me with your reference where you read it, and I'll try to check it out.

234313[/snapback]

Sorry, I do not have those references available but I do remember reading a couple of times where a few isolated manufacturing facilities were still producing good quality equipment up until the end of the war.

 

One of the references was specifically about "secret" Japanese aircraft factories located within the mountains (possibly even Mout Fuji itself - I don'tr recall) that were more or less uneffected by US bombing raids.

 

I can not say for certain that any of these factories produced Ha-45s or Franks in any quantity but they could have.

Edited October 13, 2005 by pfcem

[hojutsuka]

Sorry, I do not have those references available but I do remember reading a couple of times where a few isolated manufacturing facilities were still producing good quality equipment up until the end of the war.

 

One of the references was specifically about "secret" Japanese aircraft factories located within the mountains (possibly even Mout Fuji itself - I don'tr recall) that were more or less uneffected by US bombing raids.

 

I can not say for certain that any of these factories produced Ha-45s or Franks in any quantity but they could have.

234360[/snapback]

It is certainly unfortunate that you do not seem to be able to provide references for the assertions you have made. I do know a little about the aircraft manufacture dispersal efforts, and while many of the dispersed "factories" were never bombed, the dislocation, lack of proper tooling, difficulty of supply of parts, and use of unskilled labor meant that the production was very slow and quality poor.

 

Were your sources in English or Japanese? Books or original reports/articles of some sort? About when did you read it, and if books, were they published about that time or earlier? What were the general subject of the book(s), reports, or whatever?

 

Hojutsuka

[Guest pfcem]

It is certainly unfortunate that you do not seem to be able to provide references for the assertions you have made.  I do know a little about the aircraft manufacture dispersal efforts, and while many of the dispersed "factories" were never bombed, the dislocation, lack of proper tooling, difficulty of supply of parts, and use of unskilled labor meant that the production was very slow and quality poor.

 

Were your sources in English or Japanese?  Books or original reports/articles of some sort?  About when did you read it, and if books, were they published about that time or earlier?  What were the general subject of the book(s), reports, or whatever?

 

Hojutsuka

234385[/snapback]

One book was a relatively older book (I am just guessing but probably published during the 1960s) I browsed through at a public library (most likely in Phoeniz, AZ or San Diego, CA).

 

The other was a more recent book (most likely publish within the last 5-10 years) I browsed through at Barnes & Noble or Borders.

 

I also seem to recall at least one other book/article from somewhere but it was long ago.

 

Of course, with the kind of material that gets published these days, anything less than ~10 years old could be incorrect.

 

My understanding of the Ha-45 (I could be wrong) is that it would have been impossible to produce a running engine if the tollerances where not within a reasonably good range.

 

Just as good maintainence & pilots were hard to find in Japan in 1945, quality production machinery & skilled labor were as well - but not impossible.

Edited October 13, 2005 by pfcem

[John Nelson]

Interesting thread.

I have no technical data to add to the discussion, but it did inspire me to fire up Pacific Fighters on my PC again, which in turn reminded me that the Frank was a nice-looking bird.

Some screenshots:

 

 

[hojutsuka]

One book was a relatively older book (I am just guessing but probably published during the 1960s) I browsed through at a public library (most likely in Phoeniz, AZ or San Diego, CA).

 

The other was a more recent book (most likely publish within the last 5-10 years) I browsed through at Barnes & Noble or Borders.

 

I also seem to recall at least one other book/article from somewhere but it was long ago.

234398[/snapback]

If that's your idea of research to back up your pronouncements, I guess I'll file your comments under "Unconfirmed Internet rumours/urban legends"!

 

Perhaps you might write up your thoughts about the Ki-84 and submit it to the Journal of Irreproducible Results. Seems right up their alley!

 

Hojutsuka

[Guest pfcem]

If that's your idea of research to back up your pronouncements, I guess I'll file your comments under "Unconfirmed Internet rumours/urban legends"!

 

Perhaps you might write up your thoughts about the Ki-84 and submit it to the Journal of Irreproducible Results.  Seems right up their alley!

 

Hojutsuka

234542[/snapback]

OK then, submit your proof otherwise.