Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: RotBaron on August 06, 2013, 01:38:08 PM
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Requesting information and sources regarding the combat history of the aircraft.
I've seen a lot of the wiki and wiki-like info/data, of course some of it is useful, but most makes no mention of its' actual performance.
I've been browsing a lot of websites and the like, and Icepac I keep seeing your name in various forums. I've also seen your posts here. Do you have any good sources?
My queries don't yield much...I've tried combinations of "J2M combat history, confirmed kills, and so on...to little avail.
I've found a lot of interesting information and the majority of it hearsay and opinion. Looking for more of "just the facts ma'am" type info.
However, I found a good write up but the source of such info isn't attributed: http://forums.ubi.com/showthread.php/44161-J2M-Raiden?s=8b64310c1064b3279207d732ac398fc7
Thanks.
Rot
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I can't answer your questions, but this was an interesting thread about the J2M a couple of years ago:
http://bbs.hitechcreations.com/smf/index.php/topic,305660.0.html
I'd love to see it added to AH.
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I found it as a relatively unused plane in Warbirds circa about 2005 and it flew like a truck........but a fast truck.
Then they found some sort of mistyped variable in the drag and warbirds did a change of the CoFL around that same time which turned it in an uber champion and probably better than it should have been...........so I stopped flying it.
I'm not sure if they adjusted it since then but it should perform much like a KI44 but with a steeper climb and higher top speed and only slightly less maneuverable........but the maneuverability reputation among japanese pilots was in comparison to the A6M, KI27, and KI43 which were turn champions.
This doesn't mean it couldn't turn.
It had a laminar flow wing but I can't find any airfoil profile that has a naca number that is close.
I'd love to find out the exact profile of the wing because it allowed some pretty good slow turning uncommon with that kind of wing size and aspect ratio.
I preferred the J2M2 which gave a little bit of extra speed at the expense of replacing one 99 type 2 with machine guns which I felt ok since the mixture of 99-1 and 99-2 had different trajectories.
Akamatsu had success with it but there are films of them being shot down but..........I think a pilot with the amount of experience that Akamatsu and a few others had could exploit many of it's traits to thier advantage much like Alexander Pokryshkin was able to do with the mig3.
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I've been reading a lot on the J2M, what is odd is almost all the websites begin with a nearly identical introduction about the aircraft, yet almost all of them differ on things like speed, climb and even in some cases more structural aspects.
I'm finding it very difficult to find "combat" related information, aside from a handful. There is a lot of information I can't do anything with because it's in Japanese (though.)
I wonder what Mitsubishi's records would be, where to find them or if they desired to keep much from this dark chapter of their history.
Also on the J2M5, I see 43 were built and I see 34 were built. Someone was dyslexic or misheard and many are copying the wrong number there.
Anyone know if there is an account of the oblique firing 20mm landing significant damage? I'm having a hard time imagining anyone wanting to get under a B-29, and in 20mm range to try and open fire with it. That would require at one point flying somewhat level under it and doing some serious multitasking whilst the belly gunner has one focus: the J2M.
This is proving to be a difficult plane to find reliable and verified information about.
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Necrobump..........what's wrong with this picture?
(http://silverhawkauthor.com/images/site_graphics/Aircraft/Japan/Mitsubishi-J2M3-Raiden--Jack---TAIU-SWAPA-S12---Clark-Field--Philippines--June-1945--4-.jpg)
Didn't think a single picture was worthy of a new thread so I added it to the collective here.
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The American required to pilots to flt the airplane.
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Back in the 90s during the era of Email Newsgroups, we used to chat with a B-17/B-29 bombardier. He said the J2M was the only high altitude Japanese aircraft that they encountered on any frequency. So at least we know it had the speed and high altitude performance to intercept B-29s.
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Some data from the TAIC's analysis of a captured Raiden is available here:
http://www.wwiiaircraftperformance.org
They show a top speed in excess of 410 mph, however I think that is disputed because the octane rating of the avgas used by TAIC was higher than what Japan was using.
Still, climb rate > 4600 fpm, top speed in the neighborhood of 400 mph and 4x20mm cannon would make it pretty competitive in the MA.
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Some data from the TAIC's analysis of a captured Raiden is available here:
http://www.wwiiaircraftperformance.org
They show a top speed in excess of 410 mph, however I think that is disputed because the octane rating of the avgas used by TAIC was higher than what Japan was using.
Still, climb rate > 4600 fpm, top speed in the neighborhood of 400 mph and 4x20mm cannon would make it pretty competitive in the MA.
I think you'll find that non-TAIC numbers show it was slower than the Ki-84 we already have and had a much lower FTH as well. It would be around 370mph at 16K.
That would put it about par with our Ki-61, which was woefully obsolete in 1944 when the J2M was starting to show up:
(http://www.hitechcreations.com/components/com_ahplaneperf/genchart.php?p1=78&p2=47&pw=2>ype=0&gui=localhost&itemsel=GameData)
Remember that they had been trying to produce it since 1942 after the Battle of Midway. Setbacks, technical issues with the engine/cowling, bombing factories causing delays etc etc meant that the design didn't roll off the line and into the hands of units until (mostly) Feb 1944. By that time, the N1K2 and the Ki-84, the A6M5b, and other designs were already around. It was too little, too late.
So, it wouldn't be any kind of super plane. It would still be quite the underdog. It would be very cool, though.
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If wiki data can be relied on in this case, it should be better than the Ki.61 - much more power but lighter airframe = much better climb rate, slightly lower wing loading and better gun package. I'm guessing it'd have better rear visibility than the Hien also.
It'd be Japan's fastest climbing interceptor, very well-armed at that. It;d prolly steal flyers from both the Ki.61 and N1K2 ranks...
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Which wiki numbers? They seem a bit inconsistent. The J2M3, which was really the only real version to consider since nothing after that made it into any real kind of production, had a heavier empty weight than the late-era Ki-61 which we have in-game. Earlier Ki-61s would have been even lighter and more nimble.
The J2M3 also had a very high landing and stall speed, between 100 and 130mph depending on varrying comments I've seen. That means the wings, which had generally the same surface area as the Ki-61, were shorter in span, thicker in chord, but also less efficient in lift. They were high speed wings, not climbing wings.
In general terms, Francillion was noted as saying the N1K was better overall and more maneuverable and had better range and visibility out the back on top of that. TAIC pilot comments indicate the ailerons stiffen up very early even at cruising speeds and rolling is extremely hard as low as even 325mph. The J2M2 didn't even meet the original climb specs of the order, but with the J2M3 it sank further away from that, earning the dislike of pilots for its performance. They appreciated the extra firepower, however, replacing the 2x7mm with 2x20mm, even though they were the older type.
The 4800 fpm climb numbers are from the TAIC captured test which admittedly has much higher performance using better avgas than the Japanese were able to pull off. These are the same folks that got ~430mph out of a Ki-84, remember. Those numbers are also based off the 3-gear-supercharged J2M5 if I recall. Not the actual combat J2M3 version. There were only about 30-something J2M5s built, and those were horribly unreliable per pilot claims. Yet, most numbers you see are so fantastical because they're a perfect-condition TAIC J2M5 with 91+ octane avgas.
They're not realistic numbers, is what I'm getting at.
Would be a nice addition to the game, maybe, but I wouldn't want some fantasy variant that was uber or anything when it was really just kind of "okay" for its time.
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Here's specs from the Wikipedia entry for Mitsubishi J2M (https://en.wikipedia.org/wiki/Mitsubishi_J2M#Specifications (https://en.wikipedia.org/wiki/Mitsubishi_J2M#Specifications))
Specifications
Data from Mitsubishi J2M3-21 Raiden
General characteristics
Crew: one, pilot
Length: 9.70 m (32 ft 8 in)
Wingspan: 10.80 m (35 ft 5 in)
Height: 3.81 m (13 ft 0 in)
Wing area: 20 m² (216 ft²)
Empty weight: 2,839 kg (6,259 lb)
Loaded weight: 3,211 kg (7,080 lb)
Powerplant: 1 × Mitsubishi MK4R-A Kasei 23a 14-cylinder two-row radial engine, 1,379 kW (1,850 hp)
Performance
Maximum speed: 596km/h （370 mph, 322kt） (@5450m)
Range: 560 km (302 nmi, 348 mi)
Service ceiling: 11,430 m (37,500 ft)
Rate of climb: 1402 m/min (4,600 ft/min)
Wing loading: 174 kg/m² (35 lb/ft²)
Power/mass: 0.42 kW/kg (0.26 hp/lb)
And for the Ki.61: https://en.wikipedia.org/wiki/Kawasaki_Ki-61#Specifications_.28Ki-61-I-KAIc.29 (https://en.wikipedia.org/wiki/Kawasaki_Ki-61#Specifications_.28Ki-61-I-KAIc.29)
Specifications (Ki-61-I-KAIc)
Data from Japanese Aircraft of the Pacific War
General characteristics
Crew: 1
Length: 8.94 m (29 ft 4 in)
Wingspan: 12 m (39 ft 4 in)
Height: 3.7 m (12 ft 2 in)
Wing area: 20 m2 (220 sq ft)
Airfoil: NACA 2R 16 wing root, NACA 24009 tip
Empty weight: 2,630 kg (5,798 lb)
Gross weight: 3,470 kg (7,650 lb)
Fuel capacity:
Internal 550 l (150 US gal; 120 imp gal)
External 2x 200 l (53 US gal; 44 imp gal)
Powerplant: 1 × Kawasaki Ha40 inverted liquid-cooled V-12 piston engine, 864 kW (1,159 hp)
Propellers: 3-bladed variable pitch propeller
Performance
Maximum speed: 580 km/h (360 mph; 313 kn) at 5,000 m (16,000 ft)
Range: 580 km (360 mi; 313 nmi)
Service ceiling: 11,600 m (38,100 ft)
Rate of climb: 15.2 m/s (2,990 ft/min)
Time to altitude: 7.0 min to 5,000 m (16,000 ft)
Wing loading: 173.5 kg/m2 (35.5 lb/sq ft)
Power/mass: 0.25 kW/kg (0.15 hp/lb)
I think that's our Ki.61, and it apparently sourced from Francillon. Not sure about the J2M3 specs
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I followed a reference in the wiki J2M article and its from a TAIC document. Odd though, the text lists top speed as 370 mph, which is inconsistent with what I thought we know about the TAIC numbers - but the TAIC document referenced lists the top speed @ 407mph. So I take your point about inconsistency in the data.
Either way, the requirements for a successful interceptor should be a fast climb and hard hitting gun package - which I think the J2M3 possesses. 1850 hp engine on a 7,080 lb (loaded) airframe indicates to me it should climb very well, and 4600 fpm seems reasonable. If the 4600 fpm number is dubious due to TAIC testing with higher octane gas, even if you knock down the climb rate by the same percentage as the speed discrepancy, you still get 4100+ fpm, which is still pretty dang good. Disappointed to learn about the pilot comments regarding low roll rate at high speed though.
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Even if you knock down the climb rate by the same percentage as the speed discrepancy, you still get 4100+ fpm, which is still pretty dang good.
Agreed! I was just thinking about how good it would be in that respect; *drool*!
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LOL.....many of you still don't understand that simply putting higher octane gas in a plane designed for low octane gas will do nothing to improve the performance.
That only works on cars that have knock sensors in their digital fuel injection systems.
Didn't any of you read the recent thread about this?
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LOL.....many of you still don't understand that simply putting higher octane gas in a plane designed for low octane gas will do nothing to improve the performance.
That only works on cars that have knock sensors in their digital fuel injection systems.
Didn't any of you read the recent thread about this?
I know right! They (the plane mechanics) tuned the engines injection systems to work with the gas they had, not gas they WISHED they had. Performance is performance. I can bet that any performance figures from the country of origin is based on gas they HAD. Not post-war stuff.
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The difference in octane rating was always the explanation I'd heard for the higher TAIC numbers. I'm not sure what numbers the TAIC numbers are in disagreement with, since it seems unlikely that Japan would publish performance data for an aircraft developed during wartime...
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Oboe, there's more to it. If an engine is designed for 87 octane and you put 100 octane in, you need to tune and adjust it so you can get more compression out of it.
If the engine is designed and built to run on 130-octane because you were far too optimistic, then you down-rated all the power settings in all your pilot training and all your documentation, you could much more easily put 100 octane in it and get more from it.
The latter is closer to the situation the Japanese were finding themselves in. That other octane thread wasn't very useful IMO and there wasn't much "discussion" -- just one point of view trying to promote a preconceived notion, not trying to find the real answers.
The truth is that the TAIC numbers on numerous tests with captured Japanese aircraft achieved better performance out of their retuned or repaired engines than the Japanese who flew them in combat enjoyed. Any and all TAIC numbers should be discounted across the entire field of aviation testing. At the time it was all they had, but it was flawed testing methodology and flawed results.
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Oboe, there's more to it. If an engine is designed for 87 octane and you put 100 octane in, you need to tune and adjust it so you can get more compression out of it.
If the engine is designed and built to run on 130-octane because you were far too optimistic, then you down-rated all the power settings in all your pilot training and all your documentation, you could much more easily put 100 octane in it and get more from it.
The latter is closer to the situation the Japanese were finding themselves in. That other octane thread wasn't very useful IMO and there wasn't much "discussion" -- just one point of view trying to promote a preconceived notion, not trying to find the real answers.
The truth is that the TAIC numbers on numerous tests with captured Japanese aircraft achieved better performance out of their retuned or repaired engines than the Japanese who flew them in combat enjoyed. Any and all TAIC numbers should be discounted across the entire field of aviation testing. At the time it was all they had, but it was flawed testing methodology and flawed results.
Thanks Krusty-
But how do we know what kind of performance the pilots who flew them experienced? After-the-War personal interviews? Captured documentation from Japanese aircraft manufacturers or military?
I've also heard the Japanese fuels suffered from "quality" problems but not sure if that just referred to lower octane ratings or actual contamination from either production or transportation difficulties.
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This is a bit of the problem. Japanese testing wasn't as methodical or logical as some Western counterparts. It also either wasn't documented very well or a lot of the records were lost.
For example, some noted Japanese aces didn't even know what throttle settings they used or the horsepower they were running. They knew what they needed and in my own words was much more of an analog "fly by feel" type of thing at times. Some didn't even recall which type of plane sub-model they flew. However there are some documents and some tests. They are spare but they can be found. They also reflect the down-rating of most late-war engines because of battlefield conditions, bad fuel, lack of quality control when either the engines or even things like pushrods, crankshafts, etc are made. They reflect these problems and also the math seems to add up better.
Remember that towards the end of 1944 into 1945 they were creating turpentine from tree sap (one of the few resources they could make it with) and then thinning down their gas stocks with it because the refining process for the gas was so crude. If they got 87 octane it was a good day. There is even a number of records that the A6M3 was supposedly designed and built for 130 octane but this simply was never available outside of a test.*
It's a murky area, so some people like to cite the abberant TAIC records as gospel because it's easy, even if inaccurate.
* = citation needed, I recall reading about it on this forum, but not if it was m2, m3, or if it was 100 octane or 130 octane. You get the gist of it, though.
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Krusty,
How exactly does one "tune" and engine to get more compression out of it? You could get higher manifold pressures and maybe change the ignition timing but you cant get more compression other than changing the piston and/or cylinder head.
All the higher octane means is it slows detonation issues and allows higher MAP settings.
I'm sure the Japanese had to reduce MAP because of poor fuel and detonation issues and thus would have less than rated HP.
You could design an engine with a certain compression ratio and a higher ratio may need higher octane fuel to reach it's maximum manifold pressure,but that engine will still run at lower setting as long and you dont get pre-ignition detonation using a lower rated fuel. It may be necessary to change the plugs and adjust ignition timing but thats all they did when the US went to 150 octane!
:salute
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Sorry Krusty.........they did not deviate from the factory manuals.
They did not "retune" the engines.
Do you even know how much work goes into tuning an engine?.........something I am paid sometimes $500 for a single dyno session?
The engines were not "retuned" to take advantage of the higher octane.
All that happened is that they had a higher safety margin which made it safer to fly them.
Remember how many planes tested after the war had incomplete testing?
There is a reason for that.
Unlike the planes captured during the war which were picked apart and tested endlessly, most planes tested after the war were run until they failed and little time was spent fixing them.
They were often scrapped for minor problems and not fully tested.
Why?......because the war was over.
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Ice, don't confuse what YOU do on engines with what was done in WW2. It was very much a wild west of engine maintenance and repair. They did a lot of things (documented, too) which you wouldn't ever do.
Especially the Japanese, who designed an engine for x horsepower on y gasoline and only ended up producing 2/3 x with z gasoline, so they derated the engines.
Even the Germans derated the engines on Fw190s that were more war weary from the fighting in the west and moved them to the Russian Front. Same engine, same everything, just worn and can't make as much power output, so they derated them and only allowed certain RPM/ATA as the max power settings.
It happened, and it was NOT abnormal.
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You are incorrect and arguing way out of your skill level.
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What did the Pratt & Whitney reps do to R-2800s in the ETO on P-47s to get more HP out of them?
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First they got a prop that could make use of the extra horsepower, then they raised boost and implemented water injection to combat detonation.
Later, they raised the usable rpms but I don't remember if they changed the gearcase ratios.
I visited my friends at udvar hazy this week in the restoration department and we discussed testing of enemy warbirds after the war.
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How exactly does one "tune" and engine to get more compression out of it?
(https://imgflip.com/s/meme/Captain-Picard-Facepalm.jpg)
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Back in the 90s during the era of Email Newsgroups, we used to chat with a B-17/B-29 bombardier. He said the J2M was the only high altitude Japanese aircraft that they encountered on any frequency. So at least we know it had the speed and high altitude performance to intercept B-29s.
Alt.games.warbirds and alt.games.air-warrior.........also was in alt.games.duke3dediting.
I posted at those two as well as rec.martial-arts and a ton of car and airplane related newsgroups.
J2M was fun in warbirds but that CoFl change in 2005 or so really made it more uber than it should have been.
Stopped flying it after that.
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I think you'll find that non-TAIC numbers show it was slower than the Ki-84 we already have and had a much lower FTH as well. It would be around 370mph at 16K.
That would put it about par with our Ki-61, which was woefully obsolete in 1944 when the J2M was starting to show up:
(http://www.hitechcreations.com/components/com_ahplaneperf/genchart.php?p1=78&p2=47&pw=2>ype=0&gui=localhost&itemsel=GameData)
Remember that they had been trying to produce it since 1942 after the Battle of Midway. Setbacks, technical issues with the engine/cowling, bombing factories causing delays etc etc meant that the design didn't roll off the line and into the hands of units until (mostly) Feb 1944. By that time, the N1K2 and the Ki-84, the A6M5b, and other designs were already around. It was too little, too late.
So, it wouldn't be any kind of super plane. It would still be quite the underdog. It would be very cool, though.
I can't believe that decades after the 389 mph top speed of the Ki-84 has been thoroughly debunked, this ridiculous chart is still using that grotesque figure as a reference... Read captured pilot interrogation accounts for Pete's sake... Or Iwo Jima Radar operator opinions...
The Ki-84 was a 700 + kph fighter (420 mph), as it should very well be with anywhere near the low weight and high power that it had. To believe otherwise is just to ignore common sense...
The Ki-44 was 650 kph, so around 405 mph, as quoted in official Japanese documents about the defense of Tokyo.
Only the Ki-61-1 appears anywhere near the usual quoted figures, being around 595 kph.
And so was the Ki-100, which, despite that and an extra 200 lbs over the 61, did not keep it from whipping single handed 3 X Ki-84s, switching pilots, and repeating the same feat. (A superiority achieved by using turn-climbing, then firing while turning or diving from the gained altitude, it seems)
With 1800 hp of course the lightweight J2M was a 400 mph fighter... The Navy had better fuels, and yet the the Ki-84 was 420 mph...
That the Zero have WEP only in the later 52C models (as claimed elsewhere here) is also highly suspect, since its pilots are quoted that it had only "a little more boost" in the later 52bs. 52s were likely 590 kph and earlier models around 560. 52cs were slower than 52bs due to increased weight...
Japanese boost was ten minutes, and no official figures recorded its performance values, since the Japanese kept only lower setting data. That the J2M was 650 kph capable is perfectly obvious to anyone who reads any encounter with P-51s. How can these absurd low speed values rise from the grave where they have been buried nearly 20 years is really beyond me.
Gaston
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Necrobump..........what's wrong with this picture?
(http://silverhawkauthor.com/images/site_graphics/Aircraft/Japan/Mitsubishi-J2M3-Raiden--Jack---TAIU-SWAPA-S12---Clark-Field--Philippines--June-1945--4-.jpg)
Didn't think a single picture was worthy of a new thread so I added it to the collective here.
For those who wondered...
(http://pwencycl.kgbudge.com/images/J/J2M_Jack.jpg)
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You can change the compression ratio just by changing the timing.
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https://www.scribd.com/document/133052864/Mitsubishi-J2M-Raiden
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(https://i.imgur.com/AYKdzGk.png)
(https://i.imgur.com/yfIJ8YO.png)
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You can change the compression ratio just by changing the timing.
I'm unsure how this could happen?
I always thought the compression ratio was the difference in volume at bottom dead center compared to the volume at top dead center and was a fixed ratio given the difference. It can be changed by either increasing/decreasing the volume at either TDC or BDC but not sure how adjusting the ignition timing could effect it.
Now there are variable compression engines but these werent used in any airplane that I know of.
:salute
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Changing the level of boost in a forced induction engine effectively changes the compression ratio. This is something I haven't seen anyone mention yet. It is true that high octane fuel in a car that doesn't require it has no real effect on increasing performance, in a plane of these types where you can control manifold pressure different dynamics are in play. I presume that when using the lower octane fuels, even if the aircraft were not artificially limited on the ground by the maintainers to prevent higher MP settings, the pilots would be forced to when they started getting detonation. That said, you could probably get away with it for a short time in an emergency I would think, albeit with the potential for engine damage?
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I'm unsure how this could happen?
I don't believe it could happen.
Nor does changing boost alter the compression ratio.
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If increasing the boost changes the c-r then why were Merlin engines always 6:1 c-r when the boost went from 6lb to 25lb boost?
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Before you boost anything you have to have the pistons and other internals be able to hold up to the boost. Timing would have to be changed to allow the valves to operate to wider/longer. Lift and duration. Or valve size would have to be changed. Designing an engine from the get go with planed boost is a piece of cake. However if you have insufficient fuel quality it's not going to make much of a difference. Heads, pistons and timing the key. Along with other forged internals. Just an opinion, with a Raiden over 7000 lbs, a small laminar flow wing. I would say I would have to call BS on the climb rate with the power plant that didn't compare to an R2800. Just say'in.
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Just an opinion, with a Raiden over 7000 lbs, a small laminar flow wing. I would say I would have to call BS on the climb rate with the power plant that didn't compare to an R2800. Just say'in.
The wing loading is the only issue with the J2M. It's weight and engine power are marginally better than a 109K-4. The wing is the only bit holding it back - expect horizontal acceleration to be at K-4 levels.
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The TAIC teams only had 2 flights in it, after which the engine died and they dead sticked it. During those two flights the engine ran rough and it is noted that not only was the engine "brought back to operation" for the tests but that the prop was swapped out from a hydraulic to an electric. This to me sounds like significant work was done and it was not operated in any way like the actual Japanese units would have run it.
This has been my point all along: You can't trust the TAIC reports in terms of performance. Especially when they only flew it up to 325mph (or so, they don't mention top speed, just when the controls start getting hard to manage) and didn't even try to push it to its limit. I doubt they could have considering the notes on engine performance.
Given this, even with the TAIC report they give it 370mph top speed at 5400m, which is slower than a Bf109G-6 at the same altitude.
Do NOT expect K-4 acceleration, is what I'm getting from all of this.
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At the time of the report, why was the number 325mph so important for pilots reading to know versus ever mentioning higher speeds by number?
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The TAIC teams only had 2 flights in it, after which the engine died and they dead sticked it. During those two flights the engine ran rough and it is noted that not only was the engine "brought back to operation" for the tests but that the prop was swapped out from a hydraulic to an electric. This to me sounds like significant work was done and it was not operated in any way like the actual Japanese units would have run it.
This has been my point all along: You can't trust the TAIC reports in terms of performance. Especially when they only flew it up to 325mph (or so, they don't mention top speed, just when the controls start getting hard to manage) and didn't even try to push it to its limit. I doubt they could have considering the notes on engine performance.
Given this, even with the TAIC report they give it 370mph top speed at 5400m, which is slower than a Bf109G-6 at the same altitude.
Do NOT expect K-4 acceleration, is what I'm getting from all of this.
So where did TAIC come up with the 1,850 hp figure, then?
My comparison to the K-4 is based solely on power-to-weight, with the J2M being better in this regard. The fuselage, which seems to be higher drag, would probably make the K-4 the better accelerating plane, but the J2M should be in the ballpark based on the published data.
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They probably quoted what they already had on-file or from captured pilots' handbooks about the engine, which was used in a lot of aircraft. However, as you know horsepower doesn't denote actual thrust sometimes. It took a special flat wide wooden prop blade to make effective use of the Fw190D-9's horsepower. Many engines have had prop/governor/gearbox issues which lessened their effective horsepower output. Or, even just the exhaust pipe routing can strip a lot of horsepower or add supplemental thrust, depending on the setup.
Also that 1800 hp was only a very short emergency takeoff setting and dropped to 1600 at a couple thousand meters and change and dropped to 1500 at FTH of 5000 meters and change. I think the overall design balance of the K-4s prop, engine, governing controllers, drag, weight, and all that will make it far and away a better accelerator. IMO engine problems, stalling engines, failing fuel sources and problematic prop extension shafts tend to make something not accelerate like you want when you pour on the gas. Off the top of my head I can't think of one "hot-rod" super accelerator that had as many engine problems as the Raiden.
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Regarding compression ratio and boost pressures.
You can't alter an engine's compression ratio without changing pistons or heads. Period, stop, end of story. This is a fixed number, inherent to the engine, much like (and directly related to) bore/stroke figures.
However, it isn't the ratio that causes detonation. You can take gasoline and artificially lower its octane to 10, and inject it into a 1:400 CR engine at 1/400 atm, and suffer no ill effects whatsoever, since you're not compressing the fuel mixture beyond atmospheric pressure.
By this same measure, you can take an engine and fuel pairing that run perfectly fine under atmospheric pressure, and induce detonation by simply putting it under forced induction.
Remember, the only thing that matters to the fuel is the total pressure it's under. This is the only thing the engine can do that affects the fluid properties, and thus how a reaction (ignition) propagates through the medium. The ratio between TDC and BDC doesn't matter a lick, what matters is the pressure at time of detonation. This, however, can be altered by changing the MAP and ignition timing, without affecting CR in any way.
The only way CR would need to be changed to detune an engine would be if your fuel is such crap, and your CR is so high, that you're getting compression ignition regardless of the spark plug timing.
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I think you may have misread what I said. CR is calculated by the difference in volume at TDC and BDC,so if you have a 100cc volume at BDC and a 10CC volume at TDC you get a 10:1 CR....
Just a side note,the BMW powered DviiF used and engine that would destroy itself it you used full MAP at SL,it had 2 throttles,the usual one and an altitude throttle that once you were above about 5000m you could safely open it to full.
The BMW engine had an unheard of CR of about 6.5:1! This combined with the fuels of the day would cause the engine to disassemble itself if you used WOT for both throttles,our Dvii must be a Merc powered model as it only has the single throttle.
I personally have destroyed several small 2 stroke engines.... :devil Usually from running them too lean.
:salute