Author Topic: Temporary REMOVAL of N1K1 justified? (Read 2923 times)

Yeager · « **on:** August 06, 2001, 10:57:00 PM »

Pyro said in a post made on Jun 20, 2001:

"there are some issues with N1K2 flight modeling that require some further work and changes"
====
Pyro, I cant express to you how useful it is for me to come back and read this statement often. Ive just come from the main arena and the ACM moves this FM makes are just plain rediculous compared to all the other FMs (weight and flaps and other stuff notwithstanding).

The only question I would have for you is this: When would it be appropriate to remove an item from selectability in the hanger due to newly diagnosed errors found within the physics modeling of that item (and not returned to selectability until such time as those errors are corrected).

Its seems that if the N1K1 is truly broken, and everyone agrees that it is in light of the original post, it then should be sent to the shop until its fixed.

<S>

Yeager

Karnak · « **Reply #1 on:** August 06, 2001, 11:18:00 PM »

Yeager,

I predict that you will be woefully disappointed with the revised N1K2-J. It sounds like you are expecting it to suck, I don't think it will. I think that it will be slightly less prone to retaining E, but that's about it.

I don't think the current model is anywhere near far enough off to justify removing the one good Japanese fighter.

juzz · « **Reply #2 on:** August 06, 2001, 11:18:00 PM »

It's so broken that the game engine even refers to it as the N1K2-J!

The N1K1 Kyofu (Allied: REX) is a seaplane fighter.

GRUNHERZ · « **Reply #3 on:** August 06, 2001, 11:54:00 PM »

In all my prodigious niki complaining all I ever said was that it was wierd in the vertical, especially after pulling a very hard, supposedly E draining, move just before. This is all really needs fixing in AH. Well a possibly related issue is its climb ability at 28k, where it outclimbs P51Ds.

Karnak · « **Reply #4 on:** August 06, 2001, 11:58:00 PM »

GRUNHERZ,

I'll bet the flight model issue is that it doesn't lose enough E in those hard E draining turns.

Don't know about the climb thing, never take it up that high.

Zigrat · « **Reply #5 on:** August 07, 2001, 12:46:00 AM »

who cares give us lf.ixe clip wing and niks will quake in fear

brady · « **Reply #6 on:** August 07, 2001, 08:18:00 AM »

People have to have somting to complane about, now the Chog is on a leash, the next available target is of Course the George, Face it folks In every flight sime i have played people always complane about it, Why shouldent they It was a truly outstanding plane in many respects, and it's flap system was amasing, fromm all I have read on it the flight model is what I would expect it to be.

brady · « **Reply #7 on:** August 07, 2001, 08:21:00 AM »

People have to have somting to complane about, now the Chog is on a leash, the next available target is of Course the George, Face it folks In every flight sime i have played people always complane about it, Why shouldent they It was a truly outstanding plane in many respects, and it's flap system was amasing, fromm all I have read on it the flight model is what I would expect it to be.

F4UDOA · « **Reply #8 on:** August 07, 2001, 09:10:00 AM »

Yeager,

Exactly what manuver or maneuvers are you speaking of? While I am no fan of the NIK2, I haven't really had the same experiance that some others have had. Much like the Zero in 1942 the A/C held much mystery for me until I flew it for a few sorties. While it ability to turn tightly is no surprise it can still be beaten by Spits and Zero's. And it's level speed is no match for many in the MA. I have just never witnessed the UFO type manuevers that this bird is supposed to be capable of.

My own issue with this A/C however is the mythical 1900+HP that the engine produced. Never happened since the Japanese never used better than 92 Octane fuel and the 1900HP rating was at 100 octane fuel. Also the ability of this A/C to turn was never reputed to be that good. In fact there where several battles between the F4U, F6F and NIK2 where just the opposite happened.

This is the result of any simulation which is totally dependant on data and not on history. Not that the data would give you the wrong flight characteristics, but that the right data isn't always available. I would luv to see a fligth test comparison of the NIK2 and any other fighter of it's time.

kreighund · « **Reply #9 on:** August 07, 2001, 10:35:00 AM »

Here we go again...I agree with F4UDOA if we take the Nakajima Ha-45-21 Homare of the N1K2-J and Ki-84 at the face value in the books. If you compare the output of the Pratt-Whitney R-2180 E series engines to the Homare you can get a reasonable comparison. Since both engines are of a similar volume this is about the closest youare going to get.
The P&W R-2180E is exactly 2181 cu in. Bore and stroke of 146 by 152.5mm. The same cylinders as the R-2800 but in 14 cylinders. Max RPM is 2800 and MAP is 54”.
The BHP performance figures are:
(Fuel is 115/130)
Take off
1650 SL
1800 ADI (this data comes from NACA Aircraft engine spec E-257 rev 1, P&W Twin Wasp E1, Dec 14, 1949)

WEP (ADI)
1800 to 2700'
1550 to 13Kft

MIL
1650 to 3000’
1300 to 16Kft

Normal
1400 to 6000’
1250 to 15.5Kft

Max Cruise
1300 to 8000’
1150 to 17.5K

The Nakajima Ha-45-21 (NK9H) Homare 21 is exactly 2186 cu in. Bore and stroke are 130 by 150mm. The same cylinder as the Nakajima SAKAE 21 but in 18 cylinders. The max RPM is 3000 and the MAP is unconfirmed.

The BHP performance figures are;

Take off
1670 SL
(1830 to 1970 ADI)

WEP (ADI)
1830 to 5700'
1610 to 16Kft

MIL
1655 to 9300’
1360 to 20Kft

Normal
1400 to 12Kft
1250 to 18.5Kft

Max Cruise
1200 to 15Kft
1100 to 21Kft

Remember the RPM are faster and probably the fuel is 115/130 octane from the captured A/C tests. Also the supercharger is made for a fighter application whereas the R-2180 is made for the SAAB 90A airliner.

As a comparison of an engine which normally runs on “Hi-Test” is the R-2800-B series is rated at 2100-54in (2400-56in ADI) takeoff and 1800-45in SL max continuous. With 91 grade fuel the take off is reduced to 1650-42in (no ADI) and 1380-38.5in SL max continuous.
There are other relationships which can be used to extrapolate (guess) at the power but I feel this should be close and maybe I'm on the high side...for what it is worth...

[ 08-07-2001: Message edited by: kreighund ]

jihad · « **Reply #10 on:** August 07, 2001, 10:54:00 AM »

The P&W R-2180E is exactly 2181 cu in. Bore and stroke of 146 by 152.5mm

The Nakajima Ha-45-21 (NK9H) Homare 21 is exactly 2186 cu in. Bore and stroke are 130 by 150mm.

Theoretically given the same quality of fuel the Homare 21 should produce a better torque curve than the P&W due to its undersquare bore and stroke.

Could this partially explain it's ability to zoom and hang on its prop so well?

They don't give me much trouble in the Yak-9U as long as I don't get stupid and turn with them.

[ 08-07-2001: Message edited by: jihad ]

Tac · « **Reply #11 on:** August 07, 2001, 05:44:00 PM »

"I'll bet the flight model issue is that it doesn't lose enough E in those hard E draining turns"

Completely, totally DEFINETELY agree on this.

You can pull extremely high g's and not lose 20 mph. THAT is the UFO manouver. N1k actually ZOOMS up with any plane because the plane that zooms in front of it loses most of its E on pointing its nose upwards, n1k barely loses E on that. Thats about an 80-100mph advantage right there. Then this so-called 1900HP monster engine can hang on the prop, gives it the added ability to keep its guns pointed while the other guy's plane has had to turn around or zoom down. Pingpingping n1k kills target and lazily, torquelessly noses down.

And it eats a crapload of bullets to shoot down too.. HO it in a 38 with all guns blazing from d1.0 to d200 hits scored all over it and n1k flies away undamaged or at most with a fuel leak.

Seeker · « **Reply #12 on:** August 07, 2001, 10:23:00 PM »

You HO?

batdog · « **Reply #13 on:** August 08, 2001, 06:06:00 AM »

Yea, he's a HO. Thats what Gijoe said once anyway.

xBAT

dtango · « **Reply #14 on:** August 08, 2001, 10:37:00 AM »

On the issue of reasons for the N1K2 "hanging on it's prop"...

Quote

Of the four forces acting on the airplane – thrust, drag, lift, and weight – thrust is the most difficult to measure or predict.
- Dr. John T. Lowry

It's a little more complicated than just comparing engine BHP. There are other variables that need to be factored in such as propellor efficiency and engine exhaust thrust.

Engine BHP alone doesn't tell the whole story. Infact THP (Thrust HP) is a more important indicator because we need to take into account how BHP is converted into thrust and the associated losses. Propellor efficiency plays a key role in this which then means that we have to model prop efficiency well. Remember that prop efficiency varies for a particular propellor for different flight conditions. What is the prop efficiency curve for the the N1K2? Once we get that right we might be close to estimating the amount of thrust generated by the propellor as it converts BHP into thrust.

Then we have to consider any other factors that add to the thrust as well such as engine exhaust thrust. How much thrust does the Homare of the N1K2 add to the total thrust through its exhaust?

All this serves to illustrate the complexity that HTC faces in FM's and the difficulty involved from taking "data" (assuming we can find the right data) and translating them into a FM.