N1K2 Flight Tests (Speed & Climb), Comments Pyro?

[Vermillion]

Ok, just finished the Max Level Speed test for the Aces High N1K2-J Shinden.

Protocol: Aircraft was loaded with full fuel and ammo. Climbed to 1,000 ft, and set to auto level trim. Aircraft was allowed to accelerate till speed was stable (MIL power), and after 30 seconds, IAS mph speed was recorded. WEP was applied, and after speed was stable for 30 seconds, IAS mph speed was recorded. This process was repeated at 3,000ft, and every 3,000ft thereafter to 33,000 ft.

Results

 

As can be seen from the chart, the tested IAS is averaging only 75%-85% of the IAS expected.

This result is consistent with the results of the N1K2 Climb test that I presented last week. Which also averaged only 75%-80% of the expected results.

 

Conclusion: One of several possible problems are occuring here. 1.) The data on the AW Performance Charts that I'm basing the testing on (expected results), it total trash.  or 2.) We may have a problem with the the FM of the N1K2 (If so, I would guess in the power department since both climb and speed are approximately equally effected, but pure guess though)

Pyro, could you at least tell me if the historical data is in the ballpark ??



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Vermillion
WB's: (verm--), **MOL**, Men of Leisure,
"Real men fly Radials, Nancy Boys fly Spitfires "

[gatt]

Vermillion,

I'll do the same with the C.205 when she'll roll out of the factory (compared with the few official data we have). Tell me if you wanna tha data in Excel format.

Greets,
Gatt
4th Stormo CT

[wells]

The only data I have gives it a top speed of 369mph and a climb to 6000m in 7 min 22sec
loaded weight: 8800-9000 lbs

From 2 sources, including the USAF museum (from website)

I dunno about those AW charts, Verm...

Firstly, they've converted whatever the original data was into knots so there could be a conversion factor error there and looking at the specs at the top doesn't seem to reflect the actual test conditions.  For example, the P-47 and P-51 are listed at their gross weights where there's no way they would be as fast or climb as well as those charts say.

[leonid]

Verm,
I second wells' feelings concerning those AW performance charts.  Do you have any other information available?

Actually, once the FM is finalized (if that can ever really be - what was that phrase? Oh, "The older I get, the better I was."  Think that applies well to our perception of WWII aircraft, especially our own fav's), we should probably focus more on making performance charts wrt AH, so that others can get pertinent information for the aircraft represented.

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129 IAP VVS RKKA




[This message has been edited by leonid (edited 11-11-1999).]

[Vermillion]

Guys, just to check too see if there was a conversion error or something else going on, I checked the AW chart against the P-51 and Spitfire, for just a few data points. (1k, 5k, 10k)

The P-51 was almost dead on at 1,000 ft at the tested weight listed on the AW charts. Expect 362 mph, Tested WEP at 356 mph. Thats less than a 2% error, well within conversion and tested data read errors.

The Spitfire was even closer at 1,000 ft.  The AW Spitfire, which had the Merlin 61, had an expected IAS mph of 330. My WEP tested value was exactly 330.

So while the individual data on the N1K2 may be suspect, the charts themselves seem to match very closely to the AH performance for at least the Spit and Pony.

Unfortunately Wells, no I don't have any better data. Hell, I challenge anyone to produce any better data, supporting or contradicting, because I would love to see it myself.   The N1K2 is one of my favorite aircraft, and data is very hard to get.

I however exclude single point measurements from secondary source table top reference books. We all know how inaccurate that can be, and how an error in a single book can propagate down thru hundreds.  Remember the 15mm Cannon debacle for the 109?

Just for an example take that 369 mph number. What if it was originally knots, and was erroneously reported as mph, and the error propogated. That could make the top speed at altitude aprox 420 mph, which is the approximate speed of the 190D, which has a similar weight and less horsepower than the N1K2. And if you look the AW Chart for the N1K2 and convert IAS knots to TAS mph, again its in that 420 ballpark. What a coincidence !!  

Now, thats not what I am saying happened, just illustrating that we can only rely on primary source data, especially on some of these rare aircraft such as the N1K2.

Thats why I asked Pyro, if the data was totally off, and then if so I would shut up  

And then again, its possible that there is an error in the FM. Remember Gatt found one on the La5, which was too fast.

Just reporting my best data vs tested results   Its all up to Pyro after that.

PS: Yes Leonid, I would be happy to help out on a set of charts for AH game performance. Organize a group of testors and I will participate.

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Vermillion
WB's: (verm--), **MOL**, Men of Leisure,
"Real men fly Radials, Nancy Boys fly Spitfires "

[funked]

Error propogation:

Top speed = 400 mph.

Convert to km/h for Euro book: 1.61 x 400 = 644 km/h.

USA guy picks up Euro book, writes book using 644 km/h.  644 x .62 = 399 mph.

Repeat until number is totally hosed.  

[wells]

The data I have looks pretty good to me.  It looks to originate from a primary source.  Speed is given in knots, altitude in meters etc.  The conversion factors are right on as well.  Here's the data for the N1K2

Power:  1825 hp @ 1750m
1625 hp @ 6100m
Speed:  321 kt @ 5600m
Time to climb to 6000m:  7 min 22 sec

From what I understand, the engines did not develop the rated power of 1990 hp.  

I will play with some numbers and see if the data is reasonable.

[gatt]

 

Pyro, could you at least tell me if the historical data is in the ballpark ??

That a million dollar question. I'm very curious to know how HTC calculate data for a/c like the N1K2 or the C.205, their data being so rare to find out. Any hint PYRO?

Ok, ok dont mind, I'm asking too much ...  
Cant wait for testing the C.205 anyway.

Greets,
Gatt
4°Stormo Caccia

[wells]

Here's what I came up with.  Assuming the speed and power data that I quoted is correct and using a loaded weight of 4000kg (from same source), I get a climb rate of approximately 14.2 m/s (2800 fpm) @ 19000'.  This is pretty close to the green line in Vermillion's chart (expected value), however, if I use 4300 kg as the loaded weight (such as is listed in the AW chart), then the climb rate drops to 12.7 m/s (2500 fpm) at 19k, which is much closer to the red line (tested value).  From this, I tend to think that the climb rate is too low in AH as well, although the speed is probably ok.

[danish]

From E. Brown "Duels In The Sky" ISBN 0-87021-063-7

Max Speed 407 mph at 19000f
Climb 4.000 ft\min

Brown has his opinions:

"Mustang IV Versus George 12

In this battle, a small edge in speed and maneuverab'l'ty belonged to the Mustang, but it had little margin for error.  Its high rate of roll, giving the advantage both in attack and defense, should be the deciding factor in this cat-and-mouse game.
Verdict:   The Mustang could use its all-round advantage to good purpose, but the pilot would have to work hard for victory."


danish

[danish]

While offline I see several new posts.Though I might be braking the law I might as well bring some more from Brown ;=).

"KAWANISHI NIK2-j GEORGE 12

This low midwing, single-scat fighter was developed from the Rex fighter seaplane and looked like the American Republic Thunderbolt.  It was of all-metal structure with flush-riveted, stressed skin, and all controls were fabric covered.  The cockpit was set over the trailing edge of the 39-ft, 4-in wing and was fitted with a blister-type canopy.The pilot had armor protection.
Model 12 had an uprated 2,000-hp Nakajima Homare 21, an eighteen-cylinder, two-row radial engine with a two-speed supercharger and ejector exhausts.  It drove a four-blade, constant-speed airscrew.  The fuel tanks in the fuselage were self-sealing.
Rate of climb was 4,000 ft/min.  The aircraft is reported to have had barely positive stability arolind all three axes, light and effective controls, and a rate of roll somewhere between that of the Zeke and the Tojo.  It does not appear to have been quite as maneuverable as the Hellcat more on par with the Corsair.
The predecessor model 11 with a top speed of 315 knots (363 mph), had been much used in the defense of Formosa.  Model 12 had a maximum speed of 353.5 knots (407 mph) at 19,000 ft.  Range was 929 rim (1,070 statute miles).
Armament consisted of four 20-mm wing cannon and two 7.7mm machine guns in the fuselage, synchronized to fire through the airscrew.
Assessment:   The George 12 was a high-quality, high-performance fighter that appeared too late and in too few numbers to influence the course of the air war.  It was well armed and protected-the Japanese having learned from their combat experience against the Americans."

Wells: the low engine output you report, was that a result of declining industrial quality?If so the concensus on these boards have been to accept the "what if" top notch quality - as you know better than anyone ;=)

danish

[wells]

Thanks for the info Danish!

[SnakeEyes]

 

It does not appear to have been quite as maneuverable as the Hellcat more on par with the Corsair.

I hate the term "maneuverable."  To my understanding, in the hands of a good pilot, the F4U was much MORE maneuverable than the F6F.  Better zoom, better roll, higher top speed, at least equal in initial dive I'd suspect.  To me, a turning circle does not equate to maneuverability.  Damn I hate the use of that term!  It's fewkin' useless... if not outright counterintuitive.

[funked]

Wells - I had a brief discussion with Manx at the con.  He can read Japanese and has quite a library.  He indicated that the Ki-44 was probably the fastest Japanese fighter in the field because the Homare (Ki-84 and N1K engine) did not live up to its ratings.

[Minotaur]

My info tells me the N1K2 does 363 MPH.

Mino