fubar57
General
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Ki-43 Hayabusa Performance
- Thread starter Laurelix
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XI. Turning Performance:
Altitude / Direction / IAS / Radius / Time / RPM / AMP
1969' / Left / 205 m.p.h./ 307.4'/ 10.8/ 2700/ 37.8
1969' / Right / 205 m.p.h./ 301.5'/ 11.0/ 2700/ 37.8
Note: Turns are executed without difficulty but the ailerons get heavy with increased speed.
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Comment [by intelligence analyst]
This document shows OSCAR to be a ship of fair performance, good climb, and excellent maneuverability. There is no evidence that OSCAR pilots take the restrictions seriously and they seem to get away with it. The engine limitations appear to be too stringent and the performance in ATAD #T1 is based on power ratings slightly higher than those presented here. There have been reports of OSCAR showing high "flash" performance and it is possible that some sort of power-boost may now be incorporated. There is reason to believe that Jap pilots prefer OSCAR to the higher performing TOJO and TONY.
My Comment:
Although it may be "Documented" in the manual, I believe Section XI has a translation error.
The numbers here simply DO NOT fit together from a physics standpoint unless my math is pretty far off.
I used an online calculator to convert the IAS to a TAS value and got 212 MPH.
I don't know for sure this is correct, but conclusions are not going to change much even if one uses the original 205 MPH as a TAS value which is needed to calculate for G Load.
There is also the possibility that this was not a constant rate / constant radius turn which means my numbers definitely will be off, but please follow along for a minute.
212 MPH works out to 311 feet/second (fps).
307.4 feet radius works to a circle of 1931.45 feet Circumference which is the distance that must be traveled.
Time = Distance / Velocity, so Time should be 6.21 Seconds. ---- WOW! Cool!
Now if we calculate Velocity based on Distance / Time (assuming Constant Speed and Radius), we get 178.84 fps or 121.93 MPH.
The interesting thing here is that if we convert this to km/hour, we get about 198 kph which isn't that far off the original velocity listed.
My GUESS is that someone doing the number conversions didn't realise that OSCAR is basically an armed cotton ball and has a ridiculously low stall speed. The 205 KPH (212 KPH TAS) is really an entry speed into the turn which is done at somewhere in the neighborhood of 3.8 G and winding down to about 2.9 G as speed bleeds off to about 184 KPH TAS.
The numbers fit together pretty well with these assumptions and the calculated 1 G stall speed from these numbers is somewhere at or below about 68 MPH.
This is all just calculations with a bunch of assumptions thrown in, so you determine the plausibility.
- Ivan.
XI. Turning Performance:
Altitude / Direction / IAS / Radius / Time / RPM / AMP
1969' / Left / 205 m.p.h./ 307.4'/ 10.8/ 2700/ 37.8
1969' / Right / 205 m.p.h./ 301.5'/ 11.0/ 2700/ 37.8
Note: Turns are executed without difficulty but the ailerons get heavy with increased speed.
.....
Comment [by intelligence analyst]
This document shows OSCAR to be a ship of fair performance, good climb, and excellent maneuverability. There is no evidence that OSCAR pilots take the restrictions seriously and they seem to get away with it. The engine limitations appear to be too stringent and the performance in ATAD #T1 is based on power ratings slightly higher than those presented here. There have been reports of OSCAR showing high "flash" performance and it is possible that some sort of power-boost may now be incorporated. There is reason to believe that Jap pilots prefer OSCAR to the higher performing TOJO and TONY.
My Comment:
Although it may be "Documented" in the manual, I believe Section XI has a translation error.
The numbers here simply DO NOT fit together from a physics standpoint unless my math is pretty far off.
I used an online calculator to convert the IAS to a TAS value and got 212 MPH.
I don't know for sure this is correct, but conclusions are not going to change much even if one uses the original 205 MPH as a TAS value which is needed to calculate for G Load.
There is also the possibility that this was not a constant rate / constant radius turn which means my numbers definitely will be off, but please follow along for a minute.
212 MPH works out to 311 feet/second (fps).
307.4 feet radius works to a circle of 1931.45 feet Circumference which is the distance that must be traveled.
Time = Distance / Velocity, so Time should be 6.21 Seconds. ---- WOW! Cool!
Now if we calculate Velocity based on Distance / Time (assuming Constant Speed and Radius), we get 178.84 fps or 121.93 MPH.
The interesting thing here is that if we convert this to km/hour, we get about 198 kph which isn't that far off the original velocity listed.
My GUESS is that someone doing the number conversions didn't realise that OSCAR is basically an armed cotton ball and has a ridiculously low stall speed. The 205 KPH (212 KPH TAS) is really an entry speed into the turn which is done at somewhere in the neighborhood of 3.8 G and winding down to about 2.9 G as speed bleeds off to about 184 KPH TAS.
The numbers fit together pretty well with these assumptions and the calculated 1 G stall speed from these numbers is somewhere at or below about 68 MPH.
This is all just calculations with a bunch of assumptions thrown in, so you determine the plausibility.
- Ivan.
Last edited:
CORSNING
Tech Sergeant
George, You are the MAN! Thank you sir.
CORSNING
Tech Sergeant
Truth is, I am not quite sure what to make of the six page document.
The Gloster Gladiator II according to Russian tests was capable of
10 seconds left and 11 seconds right.
The I-153: 11.4/L & 12.4/R
At this time I am going to chock the 10.8/L and 11.0/R of the Ki.43-II
up to being initial turn and not sustained. What that means is that
these figures, in my opinion at this time, can not be compared to
the figures in the Russian tests nor the figures in Erik's books.
The Finnish B-239 was capable of a 7.0 second first 180 degrees, however
its sustained turn was 15.8 seconds.
The Gloster Gladiator II according to Russian tests was capable of
10 seconds left and 11 seconds right.
The I-153: 11.4/L & 12.4/R
At this time I am going to chock the 10.8/L and 11.0/R of the Ki.43-II
up to being initial turn and not sustained. What that means is that
these figures, in my opinion at this time, can not be compared to
the figures in the Russian tests nor the figures in Erik's books.
The Finnish B-239 was capable of a 7.0 second first 180 degrees, however
its sustained turn was 15.8 seconds.
Level sustained 360s may be interesting for comparison but not for real combat. If you need to outturn the other guy you will need to go down if you are inferior in power/weight, or up if you are superior. WW2 fighter combats go downstairs fast. I wonder if it would be a better comparison to standardise at, say, 4g at 20,000ft and compare by the loss of height. Which is what the jet guys do with specific energy.
Aircraft specific energy - Wikipedia
You can calculate a specific energy chart for WW2 fighters too.
Aircraft specific energy - Wikipedia
You can calculate a specific energy chart for WW2 fighters too.
Hello K5083,
I believe the level 360 or 180 degree turn makes more sense for comparison. The number being compared is the greatest angular change that is possible without losing altitude. This is an indication of the aerodynamic capabilities. I don't believe ANY WW2 propeller driven fighter could make a maximum rate 360 degree turn without losing speed / energy. Perhaps the Me 163 could?
Your standard 4G turn at 20,000 is really a comparison of energy bleed and totally ignores stall speed which is a very important difference.
As soon as you start playing with vertical maneuvers, it becomes a tactics game rather than a comparison of aircraft capabilities.
One of the reasons why it is PLAUSIBLE that the long wing Oscar COULD have done this kind of turn is that it was a very light aircraft with high power to weight and low wing loading which would likely result in a very low stall speed and high acceleration at this low speed to replace the speed / energy being lost in the turn. If my numbers are correct, the Oscar would have been finishing the turn at around 115 MPH at which speed it still can pull ALMOST 3 G while hanging at the edge of the stall. If this were a FW 190A or P-47, instead, it could barely stay flying at 1 G at 115 MPH, so it won't be able to turn at all.
Hello Corsning,
I don't believe that the comparative turn performance of the Gladiator and I-153 are really an indication that the turn rate quoted for Ki 43 is NOT possible. In comparing the numbers, it seems like the three aircraft should actually be fairly similar. The biplanes (Gladiator) have more wing area and a slower stall speed but also have a LOT more drag and pretty comparable power loadings. Without a starting speed or radius of turn, there are too many variables to actually calculate anything though so this is just an "impression" that even I would not bet on.
- Ivan.
I believe the level 360 or 180 degree turn makes more sense for comparison. The number being compared is the greatest angular change that is possible without losing altitude. This is an indication of the aerodynamic capabilities. I don't believe ANY WW2 propeller driven fighter could make a maximum rate 360 degree turn without losing speed / energy. Perhaps the Me 163 could?
Your standard 4G turn at 20,000 is really a comparison of energy bleed and totally ignores stall speed which is a very important difference.
As soon as you start playing with vertical maneuvers, it becomes a tactics game rather than a comparison of aircraft capabilities.
One of the reasons why it is PLAUSIBLE that the long wing Oscar COULD have done this kind of turn is that it was a very light aircraft with high power to weight and low wing loading which would likely result in a very low stall speed and high acceleration at this low speed to replace the speed / energy being lost in the turn. If my numbers are correct, the Oscar would have been finishing the turn at around 115 MPH at which speed it still can pull ALMOST 3 G while hanging at the edge of the stall. If this were a FW 190A or P-47, instead, it could barely stay flying at 1 G at 115 MPH, so it won't be able to turn at all.
Hello Corsning,
I don't believe that the comparative turn performance of the Gladiator and I-153 are really an indication that the turn rate quoted for Ki 43 is NOT possible. In comparing the numbers, it seems like the three aircraft should actually be fairly similar. The biplanes (Gladiator) have more wing area and a slower stall speed but also have a LOT more drag and pretty comparable power loadings. Without a starting speed or radius of turn, there are too many variables to actually calculate anything though so this is just an "impression" that even I would not bet on.
- Ivan.
Too many variables! What's the sense of getting all twisted up in these calculations, many of which seem to be focussed on steady state conditions of airspeed or altitude or G load, when a combat-style max effort turn at WWII thrust and weight and lift values is going to guarantee constantly varying values of all three as energy bleeds off? We talk about horsepower because that's the number we have, but thrust is really what counts. We talk of stall speeds, but the published numbers we have don't reflect the dynamic conditions we're dealing with. Bah! Fiddlesticks! As far as I'm concerned if it ain't OBSERVED and THOROUGHLY DOCUMENTED it ain't real.
Cheers,
Wes
Cheers,
Wes
CORSNING
Tech Sergeant
Amen Wes.
CORSNING
Tech Sergeant
Thank you Wes. While I agree with you completely, sometimes we
have to use what is available using caution. To Clarify, some of the
TAIC documents use performance figures based on fragmentary
documentary evidence and resultant extrapolation of engine ratings.
More than probably not exact, but all we have left of many Japanese
aircraft to use for comparison purposes.
have to use what is available using caution. To Clarify, some of the
TAIC documents use performance figures based on fragmentary
documentary evidence and resultant extrapolation of engine ratings.
More than probably not exact, but all we have left of many Japanese
aircraft to use for comparison purposes.
How about the observations of those who encountered them in combat? It's history. It happened. Why obsess over the (theoretical) minutiae?
Cheers,
Wes
Shortround6
Major General
In part because " It's history. It happened." is itself often inaccurate for one or more reasons.
Switching to the BoB for instance one German ace claimed he (and his 109) could always outturn a Spitfire. What he observed in several combats, was that he and his 109 could out turn a Spitfire being flown by a green pilot who was not flying the Spitfire to it's limits. Calculations, tests and other combat reports all agree that the Spitfire could outturn the 109. Other German pilots may have out turned Spitfires, others did not. Capability of the planes or the pilots?
Combat reports seldom list the entry speed into a maneuver, they had no G meters in the vast majority of WW II aircraft, The pilot writing the report has no knowledge of the starting speed of the enemy aircraft except in general terms. ANd no knowledge of how many Gs it was pulling except, again in general terms.
Spitfire 1 vs 109E is in fact an interesting comparison of different design philosophies. They have similar 360 turns but the fact that the 109 with slats open has a far higher coefficient of lift at high AoA gives it way different speed bleed. Basically those slats act like parachutes. The wing has to work harder to produce the same lift as the lightly-loaded Spitfire wing so the induced drag is way higher. For a short while if the 109 is pursuing it can use the high AoA to get a shot, then it loses energy faster than the Spit does and must lose speed or height and give up the turn and disengage to have another go using its climb.
Of course I can write this stuff but real combat is the only real tool of comparison. (And of course most pilots do not see the one that gets them.)
Of course I can write this stuff but real combat is the only real tool of comparison. (And of course most pilots do not see the one that gets them.)
CORSNING
Tech Sergeant
Hello XBe02Drvr,
I believe you are missing the point of WHY I was doing the calculations.
It is really for two reasons:
1. To get a better understanding of what is being described.
2. To Sanity Check the numbers being thrown about.
The actual math behind the calculations is simple: Acceleration=Velocity^2 / Radius. The spreadsheet took about 5 minutes to put together and much of that time was spent deciding whether to do calculations in metric.
I wanted to see whether the Spitfire turn that Shortround6 described was at high speed or low speed.
I was quite surprised that the 5-something G turn was quicker. That was NOT in the data but was a logical conclusion.
It was clear from the response that Corsning was as surprised as I was.
The translated Oscar manual that Eagledad posted was actually something that I already had.
I had saved it when Jim Long posted it back when he was still alive. He was a really great guy and shared a lot of very hard to get information. I just am not nearly as well organized as Eagledad.
Because I had still had the spreadsheet up from the calculations for Spitfire, I figured I would see whether the turn being described in the manual was just puttering around hanging on the edge of a stall or pulling enough G to black out the pilot.
Imagine my surprise when I plugged in the 205-212 MPH and 307 feet radius and got around 9.8 G.
THAT told me something was wrong and justified the couple minutes spent entering the data.
I spent about another 10 minutes adding a couple more calculations to make sure that the 1 G stall speed was "reasonable" as a sanity check on my own work. You already know the rest.
I could have simply posted that the turn rate listed in the manual was "impossible" but I thought a thorough explanation was more useful.
How many people over the last 75 years do you think have read the numbers in the translation and copied them down without figuring out that they simply cannot be correct?
- Ivan.
I worked in the Navy fighter training world, and I can tell you what they valued far more than technical details was operational experience and observed performance and tactical behaviors. All the instructor pilots and almost all the RIOs had been to Topgun or one of its offshoot training courses, and some of the pilots had flown one of the MiGs they had there.
Cheers,
Wes
Anybody who's turned and burned and grunted their way through it could look at those numbers and instantly see they were unrealistic. I must have been half asleep to miss them.(Don't get old; it takes the edge off you!)
Cheers,
Wes
CORSNING
Tech Sergeant
Sing it brother Wes, and I'm only 67 & under stand completely.
Hello XBe02Drvr,
I know what you mean about getting older and slower. It's a b*tch to need reading glasses to comfortably use a computer these days.
We old guys make up for it by being a lot more sneaky though!
What is really scary is that these numbers were translated by people who WERE familiar with aircraft and no one caught the errors.
I personally have so little time flying aerobatics (as a passenger) that I don't really have a feel just by looking at these numbers.
- Ivan.
It was so much fun having that T34 to play with before I got too old and too cautious to enjoy it! I've held 4 1/2 Gs through 360° with a 180 KIAS entry and consumed well over half a mile doing it (observed by landmarks) and lost near 1500 feet in the process. The precision of those observations is suspect, however, as I was pretty greyed out towards the end. Love that teenie weenie! She practically flew herself out of that maneuver, as I was too groggy to be much help. We started at 8,000 ft, so had plenty of cushion. Wouldn't have tried it in any plane I had less confidence in.
(Don't try this at home, kiddies!)
Cheers,
Wes
Why NOT try this at home? It would be the SAFEST place to do it!
It is a rare day in the Virtual skies when I don't crash SOMETHING.... Just hit the <Reset> button and try again!
- Ivan.
