Airplanes

[Symon]

Well, stepped into a pile of unintended consequences. Knew that was going to happen. Worked so hard getting fighter performance at altitude worked out that I neglected the interaction with bomber ceilings.

So bombers are going to have to get a ceiling haircut. Same deal, “operational” ceiling.

Now, the IJ is only going to have those few planes that were, indeed, devised and used as interceptors, able to reach bomber operational altitudes with sufficient “capability” to do anything.

So … it will take a bit more time to get it all righty tighty.

Oops. JWE

[Dili]

Bombers maybe should get the bombing ceiling. If they bomb at 8000m then not much more.

[Symon]

ORIGINAL: Symon
So bombers are going to have to get a ceiling haircut. Same deal, “operational” ceiling.

First things to mess with, re bombers, are the biggies, B-17, B-24 and B-29. Data sources are USAAC Aircraft Performance Characteristics data, ‘Black Book’ Characteristics Summaries, USAAC Materials Command acceptance tests, AC Material Division comparison trials, UK Aircraft Performance (A.P. 1740 series) data sheets.

B-17: Game ceiling is 36-37k. This is quite correct. However, this is the ‘100 fpm service’ ceiling for the aircraft at the “light combat” weight of ~45k lbs. The same data sheets give the 100 fpm ceiling as ~28k for the aircraft at ~65k lbs. 65k lbs represents the plane with 10k bombs and 15.4k fuel (for a basic profile), or 12.8k bombs and 12.6k fuel (for a max bomb profile).

B-29: Game ceiling is 33.6k. This one is a bit odd, since the ‘100 fpm service’ ceiling for the aircraft at the same respective “light combat” conditions (~100k for the B-29) is 40k. But the weight for most all mission profiles is ~140k (that’s with 10k bombs and 46.5k fuel, or 20k bombs and 38.6k fuel).

Obviously, it’s all in the weight of the aircraft.

Ok, so since bombers, in the game, are used to bomb, it makes sense to give them their nominal “loaded” ceilings. There are no gifties for ‘light’ loading, in the game. Extended range has fewer bombs but more fuel; same, same. One size fits all. So don’t even ask.

[ed] Game has set data parameters, that we won't mess with: load, ext load, range, ext range. So that's a stake in the ground and values will be calculated on that basis.

This won’t impact B-29s much (or B-24s and B-25s and such), because the paradigm for them apparently took this into account, but B-17s will take a significant hit, as will other “bomber” types with inconsistencies in the specifications.

Will be looking closely at loaded 'operational' ceilings.

Ciao. JWE

[sandman455]

ORIGINAL: Symon
. . . The real witch is the Ki-100.

Yeah - the real issue is the interviews with the IJ pilots who flew the Ki-100. It was a remarkably good a/c and that has to be either dismissed or something is blatantly wrong with the 360mph value that has been published and republished for the ages. Could be a sea level figure, could be a military power only figure. Who knows? I've been down this road and it leads now where. Those damn Japanese - they were better at destroying stuff after the war than they were during the war.

I'm inclined to think it is all related to the KPH, MPH, KTS fiasco of that era. The air forces of the United States was moving over to the KTS figure during this period. The Japanese reported everything in KPH. The conversions to KTS often got interpreted as MPH. It has been documented to have happened on at least a few aircraft with the N1K coming to mind. There was a good TAIC that eventually set the record straight on the N1K, years later. There is no associated documents to help with the Ki-100. All you got is a limited TAIC for the Ki-61-II that is based on fragmented documents and engineers making estimates.

They make it clear that a Ki-61 with 1500hp was going to be a beast. Very clean airframe. Their guess was something like 423mph with 1500hp under the hood. There is other tidbits of documentation that have the Ki-100 being about 3-4% slower than a Ki-61-II due to the profile of the radial engine with 1500hp. That would put it at around 406-410kts. A 360 value if it were really knots translates into 414mph. That would be fast enough for the Japanese aviators to even try to compare it with a 426mph Ki-84. Just don't know - but for me at least, there's enough there to hang your hat on.

All your other numbers are look real good. Of course I keep changing mine with each new piece of data I stumble onto. Sadly it is a never ending numbers game. I'm seriously thinking it would have been just better to toss out the top speed variable and use engine HP since it would give you raw acceleration. But then you are still stuck trying to decide what altitude for the rated HP. And there is no denying that V-NE is almost as important as V-H when it comes to A2A. And it just goes on and on. .

And jiminy crickets - who was responsible for using MPH for one variable in game and then using nautical miles for another. Fifty lashes with a wet noodle for that misguided individual.

[Symon]

Hi Gary, Thanks for the kind words. Yepperino, it is a major PITA. And it’s growing like scum on a pond.

The table is a work in progress. Not done by a long shot; if ceiling isn’t in red, I haven’t got to it yet.. I’m going to bump the Tony-II KAI up a skoosh, more in line with the TAIC reports. Got the same reports as you, the Ki-100, by all accounts, was about 12 mph slower because of the additional nacelle drag, so it should be honest to gosh pushing 400. Climb will go up, too, especially for the dash-II (it was basically a dash-I with a more poop-hot supercharger).

Anyway, what the hey, probably all wet, but at least it will be consistent. Ciao. JWE

[Dili]

I don't think Ki 100 with a radial engine and 1500hp will get 680kph. 640kph more likely. Depends crucially at what altitude the engine outputs the 1500hp. If it is at low level it might even been worse.
So the deal is at what altitude the engine gives the 1500hp. Then give the radial engine penalty.

On same note anyone knows if the japanese improved the NACA?

[Symon]

ORIGINAL: sandman455
Sadly it is a never ending numbers game. And it just goes on and on. .

Ok, Gary, here’s a little more grist for the mill.[;)]
The Ha-140 puts out about 1320HP at about 6000’ and about 1290 at about 16000’, Mil Power at 2800 rpm (I’m calling it Mil for 15 min continuous max power at max rpm). So run the calcs (using Francillon’s airframe form factors) and the numbers come out darn close to the TAIC stuff. Guess math hasn’t changed much over the years.[;)]

The big variable is weight. Francillon says 8333 TO, TAIC ran it at 7232 for a normal and 7929 for an overload fighter. Only difference in the TAIC configurations is 700 lbs of gas and externals. Anyway, run the calcs at those 3 weights and you get purt-near all the number spread in the literature. Only Cd0 change is “standard” adjust for 100gal externals for the Francillon and TAIC overload weight configs.

At 8300lbs you get about 377 at CA
At 7900lbs you get about 387 at CA
At 7200lbs you get about 418 at CA

So, I struck the externals and 700lbs from Francillon and went with 7600lbs and got:
402 mph @ 26200 CA. Admittedly, this came from the dark brown place, but I think it will serve, and it has the benefit of fitting into the model in a consistent, repeatable way.

Now, to slog through the Ki-100. Other bitch with this one is to figure out what they were doing with the turbosupercharger on the dash-II. Have lovely goodness for the Ha-112, but finding out about the 112-Ru is like trying to herd cats. Ouch.

Ciao. JWE

[Symon]

Horray !! Found the test conditions manual and now I know just what "normal" and "overload" means. So I can do the Allied stuff under exactly the same conditions as the Japanese.

Thank the enlightened Buddha for the Brits (especially the PRO). Their operational data is superb. They have Tare, Light, Mean, and Max weights for 4 to 5 load conditions and a listing of elements for each load condition, for a ton of US planes, as well as their own. Makes it soooo much easier to compare oranges and tangerines. They even did some Japanese planes, so they provide an excellent cross reference for IJ specs. Woof !!

They are aware of the 3 month customs delay for US delivery of overseas mail. With a little sweet-talking, one can get a good chunk of it by preview pdf; so long as you got the receive buffer bandwidth and have purchased an official copy of the items.

Data entry just got more fun and informative.

Ciao. JWE

[oldman45]

Wow, what a gold mine you have found!!

[Symon]

ORIGINAL: oldman45
Wow, what a gold mine you have found!!

More than I ever imagined. Spain found a mountain of pure silver in Peru: I found Dakshi and Suzanne at the PRO.

I got RAA Martlet specs with the Cyclone 205, the Wasp 3C4 and the R-1830-90. And then a ton of stuff for the RAA Corsairs with the clipped wings, and pages of evaluations by Hugh Brown, the senior test pilot, and lions and tigers and bears, oh my !!!

[Alfred]

Will you still have that much buffer bandwidth in Chile?

But back on topic, are you sharing your source material with theElf. Notwithstanding what some around here may think of their own contributions to this exercise, I rather suspect that feedback from theElf would trump others'.

Alfred

[Symon]

ORIGINAL: Alfred
Will you still have that much buffer bandwidth in Chile?

But back on topic, are you sharing your source material with theElf. Notwithstanding what some around here may think of their own contributions to this exercise, I rather suspect that feedback from theElf would trump others'.

Alfred

Yep. Chile is quite developed.

Ian's pretty busy, but I'm getting lots of real-time help and encouragement from other Air Team people. Also have Ian's collection of data and 'things'.

[MrKane]

Hi Symon,

One short question, do you plan to do something with Ki-94-II ?
As a plane never flu, there is no confirmed data available for this airframe.
Originally it should be high-altitude interceptor but with current in game climb rate it does not fit to role.

[Symon]

ORIGINAL: MrKane
Hi Symon,

One short question, do you plan to do something with Ki-94-II ?
As a plane never flu, there is no confirmed data available for this airframe.
Originally it should be high-altitude interceptor but with current in game climb rate it does not fit to role.

Hi MrKane. Yes, but the experimental models will have to wait till last. The more planes I do (and can compare with my model) the better the model converges and the more comfy I feel about using it for the "never were" planes.

I do note that the climb rate for the Ki-94 is right out of Francillon and is just about the 'time to climb' to 30k. I'm using a different paradigm for "climb". It's a sum of the averages (or average of the sums, I forget) of rates at 5k, 10k, 15k, 20k. So Ki-94 should come up a more nominal value.

We are redefininf a few things in order to have certain planes fit their roles a bit better. The "ceiling" value has gone down to realistic operational levels for both sides. Bomber ceilings are predicated on their actual operational limits. Only "some" planes will have the capability to bring down hi-alt B-types. Only "some" planes will have the capability to escort them.

The game algorithm is very complex. Pinging on one data point will paint you into a corner. The algorithm has to do A2A and everything else. The algorithm looks at many aircraft variables for many different combat modalities. It is a function of speed and climb and maneuver within each and every altitude band, and it (of course) varies with the band.

The Air Team got it right. But they didn't have the time to get all the data lined-up, self-consistent, and unified.That's what this is all about.[8D]

Ciao. JWE

[Mac Linehan]

JWE, Gents -

This is why I am addicted to and love this forum. I am not a math guy, but the Smart Guys can break it all down into tables and language that even I can understand.

I loved the AAA data - and know that the airframe/engine number crunching will be just as good.

My absolute respect and appreciation to all of you who are doing the work and making it happen, so that the rest of us can enjoy your hard work.

This thread, along with many others on the AE forum is an education that could not be found anywhere else.

Well Done, Gents.

Mac

[LoBaron]

ORIGINAL: Symon
It's a sum of the averages (or average of the sums, I forget)

[:D]


Mac nailed it. Best thread in a while.

[Symon]

While I was setting up the spreadsheet parameters for the model, I noticed a few things about very high altitude (31k+) performance. Now, there’s quite a few planes that can get to 31k, under the new paradigm, but only just. It doesn’t make sense to give them a 31k+ maneuver rating, based on 30k numerics, since they are at the 500fpm limit, and couldn’t do bloody squat with it anyhow.

So, I devised a very arbitrary calculation algorithm that divides the 31k+ band into thirds.
If you limit out in the 31-33 range, you get raped. If you limit out in the 34-36 range you get the nominal rating. If you limit out at 37+, you get your actual power rating.

Set up a little sandbox program, and this seems to work very well. Gosh, knowing what we do now, we could have done Ian’s algorithm up proud. Would have taken an additional 100 man hours of coding work, and maybe 400-500 man hours of data acquisition and entry. Just a simple 3 month delay and an equivalent $27,000 in free time. Ouch !!

Just imagine if “speed” and “climb” were put into bands, along with maneuver. Woof !!! That’s kind of what we are doing, although we are limited to what the game algorithm does. We have to be abstract, but abstract in exactly the same way for everybody. None of this searching the web for the best numbers stuff.

[ed] I know this is taking forever, but it's a lot like B'rer Rabbit and the tar-baby; tweak one thing and get stuck, so have to tweak another, and another, and, oh lordy, please don't tho' me in dat briar patch. Taking a lot longer than expected, but it should be as complete, unified and self-consistent as we can make it, at all levels.

Ciao. JWE

[sandman455]

ORIGINAL: Symon

While I was setting up the spreadsheet parameters for the model, I noticed a few things about very high altitude (31k+) performance. Now, there’s quite a few planes that can get to 31k, under the new paradigm, but only just. It doesn’t make sense to give them a 31k+ maneuver rating, based on 30k numerics, since they are at the 500fpm limit, and couldn’t do bloody squat with it anyhow.

So, I devised a very arbitrary calculation algorithm that divides the 31k+ band into thirds.
If you limit out in the 31-33 range, you get raped. If you limit out in the 34-36 range you get the nominal rating. If you limit out at 37+, you get your actual power rating.

So ingenious, wish I had thought of it. [:)]
Looking forward to seeing your final results.

[oldman45]

I have to echo what Mac wrote. Thanks

[PaxMondo]

John,

Just lovin' it here. You're doing great work. THANKS!!

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