Maneuverability vs Speed

[Wild_Bill_Kelso]

A lot of US engine tech, including jet engines in the 50's-70's, was derived from foreign designs, especially German and later mainly British ones.

 

[tomo pauk]

The AM34 (and later versions) were based on the M17, which was a license built BMW V1 V12. Development did remove it from it's origins (just like the Klimov M100s Shevestov radials diverged from the H-S 12Y and Wright Cyclone respectively), but it was still the starting point.

There was no cylinder block on the BMW VI, nor on the M-17 -

and that engine was cobbled together from a BMW VI-based engine block

- these engine featured separate cylinders.

Not to mention an AM42 taken from an Il-10 that was being restored showed the supercharger assembly, which looks like it was cribbed directly (design-wise) from a single stage Allison.

Source?

Why the M82 as a fighter engine shouldn't be counted is that it was a 1500+ hp capable engine from the start, and later versions could make over 2000 hp under WEP/take off power (though 1850 was the most common rating for like the La-7/9/11).

So should it be counted, or not?
Source for over 2000 HP WEP on M-82?

 

[BarnOwlLover]

Photos of an AM-42 restored from an Il-10:

Il-10

Sure looks to be like an Allison supercharger set up, though I doubt by this stage it was a direct copy (though I should be noted that the V1710's design dates to the late 1920s) Interesting in that the article you linked does suggest that the AM34 and later engines were a fusion between the M17/VI (same mounting points, overall dimensions, bore and stroke, even articulated con rods) and Fiat design principals as far as the block, head and crankcase design.

And according to this article, the M-82 was rated for 1900 hp at take off at 49 in/Hg:

Shvetsov ASh-82 - Wikipedia

en.wikipedia.org

I'd consider the M82 a contemporary of the BMW 801, take that as you will, since both engine have similar strengths and weaknesses in combat and in use.

I'm just trying to state/argue the point that both the Soviets and the Japanese were held back as far as design philosophy favoring smaller aircraft (even the La-5/7 wasn't particularly big) due to engine tech, of which I'd have to say that fuel quality was a big part, like even in Germany.

This is where the conflict of needing by late war standards, a heavily armed fighter capable of interception and destroying large aircraft, but still needing to be fast and nimble to deal with other fighters comes into play. This I'd say would favor powerful engines of (depending on the plane's size) the 2000+hp or at least 1500+ class. An other complicating factor would also be range. More fuel generally means a bigger aircraft, and more power (usually though a bigger engine) means more fuel gets burned. And on top of that, what maneuverability do you want, and at what speeds?

It's sort of like pick your poison, because it's highly improbable to get all of that. The P-51H Mustang I'd argue comes the closest, but even that plane, one, lacked cannon armament, and two, had somewhat weak landing gear.

 

[Gary Cain]

Watch from 5:40, the British pilots head is level with the top windscreen frame and he is a small man, the German pilot is larger but look at how much room he has in the Spitfire.

There is no doubt the 109 is a smaller aircraft. But, the pilot is strapped in to his seat with straps akin to what are used in racecars today, he isn't going to move until he hits the quick release.

 

[Gary Cain]

Never said everyone nosed over to avoid getting shot down.

I said many used the nose over as well documented and I never heard anyone say or saw in print they were uncomfortable with nosing over.

When I got my private license, I practiced nosing over in case of power failure on climbout. It wasn't exactly a tough or uncomfortable maneuver in a C-172 or a Cherokee. Of course, the only way to get either of them to 400 mph might to lose the wings going straight down. Even then, you might not get to 400 mph.

Cheers.

I paid for a ride in a Mig 15 UTI and we did a nose over at about 450 knots. Other than my stomach rising up into my mouth it was a blast!

The plane was based in Byron and a friend of a friend owned it. Hell of a ride!

 

[Shortround6]

I don't agree that Japanese fighters, at best, were 3 to 5 years behind in speed. From memory:
1940 A6M ca. 530 km/h
1941 Ki 44 I ca. 580 km/h
1942 Ki 61 I ca. 590 km/h

They were not behind by 3-5 years. More like 1-2 years.
Testing on a P-40 in May of 1940 showed speeds of 357-360mph with some assorted minor modifications. Yes this was without protection and may have only had one .30 cal in each wing. Picking the P-40 because it was going into production and everybody knew it wasn't the latest and greatest being a P-36 with a new engine.

The Japanese were introducing two speed superchargers in 1942 which is behind the curve.
The Americans were all over the place.
P-38s had turbos.
P-39 single speed supercharger.
P-40s single speed supercharger (unless the P-40F)
P-43s turbo.
P-47s turbo (not in combat but 532 built in 1942)
P-51s single speed supercharger
F4F/Martlets single speed, 2 speed and two stage, take your pick.
F4U, two stage supercharger (not in combat but 178 built in 1942)
F6F two stage supercharger (not in combat but 10 built in 1942)

The Japanese introduced two speed superchargers just in time to get wide spread squadron service against the class of 1943 two stage US fighters.
The Ki-61 production aircraft were produced 3 in Sept 1942, 5 in Oct, 10 in Nov and 15 in Dec for example.

 

[Shortround6]

There are two variables that are often overlooked.

One is altitude.
Everything else being equal a 2000hp engine at sea level, is worth about 1,000hp at 20,000ft.
Or a 1940 book claimed that a Merlin II rated at 990hp at 12,250ft at 2600rpm could have produced 1500hp at sea level assuming the fuel would support the needed boost and the engine parts were strong enough.
Not everybody has to fly around at 25,000-30,000ft like the British and US did. But the flip side of that is they couldn't.

The other variable is engine life.
The British and the US were getting longer and longer times between overhauls as the war went on even as the engines made more power (in emergency settings). The Germans, Japanese and Soviets often sacrificed engine life for higher performance. We can argue about why (better materials and so on) but they all knew (mostly) what the materials situation was. Short life engines that worked in combat were preferable to long life engines with poorer performance.

 

[tomo pauk]

Photos of an AM-42 restored from an Il-10:

Il-10
Sure looks to be like an Allison supercharger set up, though I doubt by this stage it was a direct copy

There is not even circumstantial evidence that points in that direction.

Interesting in that the article you linked does suggest that the AM34 and later engines were a fusion between the M17/VI (same mounting points, overall dimensions, bore and stroke, even articulated con rods) and Fiat design principals as far as the block, head and crankcase design.

Number of Fiat V12 engines with en-bloc cylinders, pre-dating M-34, was zero.
Number of Fiat V12 engines with DOHC, pre-dating AM-34, was zero.
M-34 started out with blade and fork rods, it did not get articulated rods instead of that until the later FRN series.

The only people claiming that M-34 used Fiat design principles are Americans - not even the Italians themselves.

I'd consider the M82 a contemporary of the BMW 801, take that as you will, since both engine have similar strengths and weaknesses in combat and in use.

Yes, M-82 was a good answer to the BMW 801, each engine with it's strengths and weaknesses. M-82 was probably more reliable - at least early on - and with similar power as early/restricted 801s, while a full-spec BMW 801D was superior in power, especially at altitude. 801 was also much heavier.

I'm just trying to state/argue the point that both the Soviets and the Japanese were held back as far as design philosophy favoring smaller aircraft (even the La-5/7 wasn't particularly big) due to engine tech, of which I'd have to say that fuel quality was a big part, like even in Germany.

Soviet designers knew that small aircraft are less draggy aircraft (unless someone botched something up), so even with not-stellar engines a good turn of speed was possible. They took advantage of specifications not calling for great firepower or fuel load.
What the Soviets didn't do was make much more of fighters with Mikulin engines (even the AM-38 will work just fine at altitudes where the usual combat on Easter front was happening; AM-39 was another missed opportunity - sorta Soviet Jumo 213A power-wise). Lingering too much with indifferent M88 radials instead of going full-bore with production of M71, or at least M82 (but here in eye-watering numbers) was also a mistake.
They didn't produce a M82-powered fighter in series until late in 1942, leaving them with a surplus of few thousands of M82 looking for 'costumer' (Yak-7 was trialed, Il-2, Pe-2, two Lagg airframes, ANT-58) between late 1941 and late 1942.

Engine tech was more than sufficient for the needs of air war in the East in 1941-44, but they missed a lot of opportunities (Japaese did that, too, lingering too much with low-powered radials and too late DB 601 copies). All of this meant that the VVS fighter pilots to fight in under-performing fighters throughout 1941-43.

This is where the conflict of needing by late war standards, a heavily armed fighter capable of interception and destroying large aircraft, but still needing to be fast and nimble to deal with other fighters comes into play. This I'd say would favor powerful engines of (depending on the plane's size) the 2000+hp or at least 1500+ class. An other complicating factor would also be range. More fuel generally means a bigger aircraft, and more power (usually though a bigger engine) means more fuel gets burned. And on top of that, what maneuverability do you want, and at what speeds?

As above - Soviets (and Japanese) have had more powerful engines to choose from, but wast majority of fighters ended up powered by meh engines. In contrast, Anglo-Americans - and, often, the Germans - tries to install their best engines on fighters, and that paid off handsomely.

It's sort of like pick your poison, because it's highly improbable to get all of that. The P-51H Mustang I'd argue comes the closest, but even that plane, one, lacked cannon armament, and two, had somewhat weak landing gear.

One does not have to have it all. Speed > maneuverability, at least before fighters were being armed with AA missiles.

 

[cherry blossom]

There is one feature of the A6M and the A7M designs that perhaps limited their performance. They were both built with the cockpit over the wings. This is "exploited" in the A6M by having double frames interacting with the wing spars and compensating for the hole in the fuselage structure made for the cockpit. However, it left very little space for a fuselage fuel tank and this started to limit the range even in the A6M3. It forces the A7M Reppu to be longer than most of its contemporaries.

I suspect that this design choice was due to the landing behaviour being prioritised as is also seen in the large ailerons of the A6M. Mitsubishi designed the land based J2M Raiden with its cockpit set back like the Ki-84, the Fw-190, the La-5, the Hellcat, the Bearcat or the Sea Fury. Only the F4F has a view forward and down comparable with the A6M.

Eric Brown did note that the A6M was very easy to land.

Added as edit: However, the Ki-43 Hayabusa and the Ki-100 but not the Ki-44 do have the cockpit over the wing but not quite as far forward as in the A6M Zero. Thus prioritising ease of landing might go beyond just carrier based aircraft.

 

[BarnOwlLover]

It should also be noted that the P-51 Mustang (all variants, even the F-82 Twin Mustang and the lightweights) also had their cockpits almost directly over the wing. This didn't seem to be a design problem or similar issue, though the P-51 was a bit longer than a two stage Merlin Spitfire (by about a foot for most models until the H and F-82).

Then again, if you look at OA length, the Zero was fairly long for it's time, as was even a single stage Spitfire, and so to were planes like the Ki-43 and Ki-84.

One advantage I suppose for this is no front fuselage fuel tank to catch fire when hit by HMG rounds or cannon shells (SS fuel tanks were good for flak shrapnel or RCMG bullets, not so much for anything much heavier, though there were reports of American and maybe British SS fuel tanks could stop .50 rounds and even on occasion 20mm shells).

I do believe from what I've been told that wing position does have a lot to do with where the aircraft's CG (at least intended) is located. Of note is the Hawker Typhoon vs Tempest. The Typhoon didn't have a front fuselage fuel tank, but the Tempest did (to boost range and make up for what the thinner wing squeezed out). Both have their wings positioned most of the way ahead of the cockpit.

 

[PAT303]

He also never claimed that?

Well we are talking WW2 fighter aircraft in combat, not civilians pottering around in Cessna's.

 

[PAT303]

If you talk with guys who flew carburetored aircraft, it doesn't take much to make the motor cut out.

I can imagine it would, I have travelled extensively across Australia and started in Series 2A/3 Land Rovers, what's funny is they could climb the desert sand dunes with the correct tyre pressure and technique but the carburetor engined Toyota's couldn't, the Rover 2.25ltre four cylinder would chug up one side over the top and down the other while the Toyota's would be blowing black smoke going up running rich as buggery then stall going back down through starvation.

 

[Wild_Bill_Kelso]

I think once they got the bendix etc. pressurized carburetors, which I think the Americans were using fairly early on, the problem wasn't so severe.

 

[JoblinTheGoblin]

You can take a look in this forum, there is a lot of topics covering japanese aircraft, and many contemporary docs can be found, as well as Allied flight tests and assessments.
Here is also a lot of data: WWII Aircraft Performance

The website doesn't seem promising as a resource for Japanese aircraft, as it uses the TAIC reports almost exclusively as its source, displaying their overly optimistic calculations. I haven't found much flight data on certain prototypes like the Ki-64 and A7M2 that appear to have actually had recorded flight speeds, and for information like Ki-84 testing speeds reaching 660km/h and beyond, which seem to be the accounts of pilots. There was a poster on this forum who was busy listing speeds for Japanese aircraft, but some of his speeds, emergency speeds in particular, were rudimentary calculations, if I recall correctly, based on a ratio.

I don't agree that Japanese fighters, at best, were 3 to 5 years behind in speed. From memory:
1940 A6M ca. 530 km/h
1941 Ki 44 I ca. 580 km/h
1942 Ki 61 I ca. 590 km/h
1943 Ki 44 II ca. 605 km/h
1944 Ki 84 I ca. 635 km/h

1936 K5054 ~560km/h
1939 He-100 ~644km/h
1942 Mustang X ~700km/h
...

Three examples. And that's not to speak of jet aircraft, heaven forbid.

I may have overstated my figure slightly, but only for the 580-600 km/h range, which production Japanese aircraft seemed to have hugged for the most part, if in good condition that is.

This seem to be official Japanese figures. Somewhere on the forum there are posts indicating the Japanese measured top speed differently than the allies.

The speeds for some Allied aircraft like the F6F also seem to be at military power, meaning that they would still be somewhat faster, especially at high altitudes.

Few fighters in the world exceeded 600 before 1942.

Certainly not at the prototype stages, which is what I'm focusing on as I'm intent on a comparison in regards to technical and industrial capacity, and to a lesser extent, foresightedness.

That said, Japan certainly was at the lower end of major powers, considering their population and industrial base. But I'm m not sure how to draw the line between major and midling. Considering what they had to work with, I don't think they did that poorly. The did make serious mistakes, as did all the combatants, some were just better able to afford them.

Sources outside of the official Japanese figures suggest triple casualties for the Japanese at Khalkhin Gol, a major battle against a Western power, at least on the ground. Admittedly, I've heard that the Japanese army at the battle was hastily organised, but that alone would reflect terribly on the Japanese leadership. Most of Japan's victories on land were against inferior Chinese armies, subpar colonial garrisons, or were rather costly. It's innovations also seemed to be fewer in contrast to those of the Western powers. One deficient area of technology that comes to mind is jet engines, rockets in general. A great power?

Edit:

Russia also favored smaller, "more traditional" fighters until the jet age...

Russian aircraft still appear to be anywhere from 10-50kph faster than Japanese aircraft, with the Yak series (Yak-9: 700kph), Mig-3: 640kph, and La series (La-7: 661kph), vs the N1K2-J: ~620kph(?), Ki-84: 635kph, J2M5: 615kph, Ki-61-II: 630kph (prototype), Ki-44: 605kph. There seems to be a similar case with Italian aircraft as well.

 

[PAT303]

I think once they got the bendix etc. pressurized carburetors, which I think the Americans were using fairly early on, the problem wasn't so severe.

The SU injection system, it was also worth another 10mph because of not having the carburetor obstruction airflow,

 

[Just Schmidt]

1936 K5054 ~560km/h
1939 P-38 ~680km/h
1942 Mustang X ~700km/h

I tried to post speed for aircraft at least being tested in a combat environment. There's nothing wrong with comparing prototypes, as long as that is with other prototypes, even if that is of less interest for me. But comparing prototypes to operational aircraft seem ... odd.

I'm not overly concerned whether to call Japan the smallest of the great, or the greatest of the small. I think you can cite remarkable disasters for all 'western' powers, insome area or another. Japan did poorly in armor and large land battles, but were rather good at sinking ships in the beginning of the pacific war. In surface combat sometimes heavily outnumbered. They had some specialities, and produced what is generally considered the best flying boat of ww2 (operational, albeit in trivial numbers). That partly was because they prioritized their best engines for those, whereas few flying boats of the other nations used more than second tier engines for flying boats. What you excel at is also a result of the choices you make.

 

[tomo pauk]

The website doesn't seem promising as a resource for Japanese aircraft, as it uses the TAIC reports almost exclusively as its source, displaying their overly optimistic calculations. I haven't found much flight data on certain prototypes like the Ki-54 and A7M2 that appear to have actually had recorded flight speeds, and for information like Ki-84 testing speeds reaching 660km/h and beyond, which seem to be the accounts of pilots. There was a poster on this forum who was busy listing speeds for Japanese aircraft, but some of his speeds, emergency speeds in particular, were rudimentary calculations, if I recall correctly, based on a ratio.

I don't't think that Ki-54 was/is of such an interest for the usual researcher of ww2 Japanese aircraft, so the test results might be a wee bit hard to find. A for the A7M - it will be a minor miracle if anything resembling the test flight report survived the war.
FWIW, there is a Ki-84 pertinent thread at the 'Videos' sub-forum here.

1936 K5054 ~560km/h
1939 P-38 ~680km/h
1942 Mustang X ~700km/h

Even the people that are otherwise very eager to flag-wave with US flag will find hard to prove that P-38 did 680 kn/h before 1943, let alone in 1939.

I may have overstated my figure slightly, but only for the 580-600 km/h range, which production Japanese aircraft seemed to have hugged for the most part, if in good condition that is.

Yes, Japanese (especially the Navy), were on the backfoot wrt. their fighter speed figures came 1943.

Russian aircraft still appear to be anywhere from 10-50kph faster than Japanese aircraft, with the Yak series (Yak-9: 700kph), Mig-3: 640kph, and La series (La-7: 661kph), vs the N1K2-J: ~620kph(?), Ki-84: 635kph, J2M5: 615kph, Ki-61-II: 630kph (prototype), Ki-44: 605kph. There seems to be a similar case with Italian aircraft as well.

Yak-9 was mostly 560-570 km/h for the best part of the war. MiG-3 botched it's prospects due to the faulty canopy retracting mechanism, that meant the ability to quickly remove it in case of danger was suspect, that in return meant that MiG was flown with open canopy, with the major speed penalty. Weak firepower necessitated installation of gondola HMGs or rockets, either of that meant that actual speed took another hit.

Italian late-war aircraft have had more of a problem of paltry numbers produced? Speed interval was between 620 and 640 km/h, the small MC.205V being the fastest of the lot.

 

[GregP]

I paid for a ride in a Mig 15 UTI and we did a nose over at about 450 knots. Other than my stomach rising up into my mouth it was a blast!

The plane was based in Byron and a friend of a friend owned it. Hell of a ride!

Had a good friend who owned one in Phoenix, Arizona. I helped put it together when he got it from China. We had a less than wonderful time with the Feds when we called them and told them the cannon were armed (not our intent ... it arrived that way). They seemed to think it was our fault. We had to point out that WE called THEM. Wasn't my airplane and I am not certain who he called. I assumed BATF.

I never got to fly in it before he passed away, but we DID start it up and taxi it at Deer Valley airport.

 

[Reluctant Poster]

1939 P-38 ~680km/h

The 413 mph often quoted was a purely paper calculation by Hibberd based on al sorts of unlikely assumptions for major modifications to the XP-38. Bodie lists them in his book. The actual speed Hibberd starts with is 380 mph.

 

[Shortround6]

The 413 mph often quoted was a purely paper calculation by Hibberd based on al sorts of unlikely assumptions for major modifications to the XP-38. Bodie lists them in his book. The actual speed Hibberd starts with is 380 mph.

One is reminded that Kelsey also did estimates based on the observed speeds done on the record breaking cross country flight that ended in wrecking the XP-38 so no proper test flights were ever done.
3 things here.
Since he was trying for a long distance record it is unlikely he ever used anything close to full speed speed and resulting fuel burn.
He was taking advantage of the very well known west to east wind pattern (used by long distances record setters of years) as a tail wind.
Unknown if his calculations made any allowance (or enough of one) for the change in drag rise in the upper 300mph speed range.

As far as the record flight goes. A Hawker Hurricane did about 640kph in 1938? (one hell of a tail wind an it was planned to take advantage of it)