Slitherine

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ORIGINAL: Big B

Dog gonnit', somebody told me those were pilot wings!

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ORIGINAL: Symon

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ORIGINAL: LoBaron
Chiming in to say I highly apprechiate that the DaBabes team finally got wings.

We've had wings for a while. Just a different kind

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ORIGINAL: LoBaron

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ORIGINAL: Big B

Dog gonnit', somebody told me those were pilot wings!

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ORIGINAL: Symon

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ORIGINAL: LoBaron
Chiming in to say I highly apprechiate that the DaBabes team finally got wings.

We've had wings for a while. Just a different kind

It did not worry you that you could play not only Born to Be Wild but the whole Easy Rider movie before reaching VLOF?

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ORIGINAL: vettim89
I am concerned about using post-war test data on IJNAF/IJAAF aircraft using superior USA produced 100 Octane AvGas vs the fuel those forces actually had available to them during the war. I understand the desire to try to distill the data into a only comparing apples to apples algorhythm but completely discarding historical realities of fuel quality seems to exclude a very important variable

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ORIGINAL: Symon

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ORIGINAL: vettim89
I am concerned about using post-war test data on IJNAF/IJAAF aircraft using superior USA produced 100 Octane AvGas vs the fuel those forces actually had available to them during the war. I understand the desire to try to distill the data into a only comparing apples to apples algorhythm but completely discarding historical realities of fuel quality seems to exclude a very important variable

Knew that was coming. It's an UTTER CROCK and categorically WRONG !!! You can't find one single source that says that. Where do people find that nonsense, anyway? It's a typical "repeat whatever's on poedopedia " thing. Tests were in 1943-45 time frame. EVERY SINGLE ONE OF THEM were predicated on 92 fuel. It said so right in the test reports. FM 42-1, Hello? Knock knock? Anybody home? Oh, God, how I hate the internet.

And if you read the post war analyses, it is clearly OBVIOUS that Japan was producing 92 CFR-M as their standard combat aviation spirit. The reports even have the cracking and additive specifications which, if one understands hydrocarbon processing, clearly show an identical product to 42-1. This was up untill 1944 when the Japanese got concerned with the amount of product, so went for a higher temp 50% point which increased the output but reduced the base octane rating, so they went with a skoosh more TEL and an additive they called Ethly Fluid, which was a mixture of TEL and a Bromine. The result was 91 CFR-M and was called Type 12, Mod-1. This worked till 1945, when output became severely problematic. So they upped the 50% and 80% temps, got more spirit, but it had such a low base octane rating that even with the addition of TEL and EF, they could only get it to 87 CFR-M. This was called Type 12, Mod-2. It's all in the source material.

CFR-M is the motor rating. The research rating is higher. It is very important to understand just what's being put in the tank. It is ludicrous to suppose that just putting 100 octane gas in a 90 octane tank will make things better. Just saying that shows that one has absolutely no idea about how engines work. Earnestly suggest you avoid poedopedia when you are looking to post "facts".

[ed] Sorry Vettim that you were the one to get whacked. You were just the first one to stick your head up. Wish it was one of the usual little weasels, but no joy. Nothing personal, pal. Live and learn, I'm thinking. But as Jerry Garcia says:
I see you've got your list out, so say your peace and get out.
Yes I get the gist of it, but it's all right
Sorry that you feel that way, the only thing there is to say is...
Every silver lining's got a touch of grey.
I will get by, I will get by, I will get by, I will survive.

J

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ORIGINAL: Symon

Ok, here’s a snapshot of some popular planes. Surprise, surprise !! Most are in the ballpark, but there’s some outstanding performers in the basket. Why is this so, you may ask. Good question.

Looking at things like HP/Wt, it’s quite apparent that both sides had very consistent views on the matter. IJ was consistently in the 16-18 range, while US was consistently in the 14-15 range. That doesn’t matter as much as it appears, since IJ performance fell off faster than US performance at higher altitudes.

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ORIGINAL: Symon

Hi Pax.

No, we won't use WEP. It has too many different meanings and too many different useable times. Just wanted to collect 'all' the data and see what's in the bucket.

Likely do weighted averages of military power, focusing on the critical altitudes. That should give a bit better performance score to planes with good high-altitude performance. Numbers are working out nicely. They are in the same ballpark with some planes being better, some not quite as good, but at least consistently calculated so the relative climb rates are smoother, even if the actual number goes up or down.

J

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ORIGINAL: vettim89
No problem JWE. Guilty as charged on repeating what I heard. I do seem to recall some specific issue with the refinery at Palembang as far as octane rating goes. Perhaps the HI stuff was not affected or perhaps that was only initially say in 1942 immediately after capture. Also guilty that I some how got the impression from the OP that the data you were using was gleaned from post war tests by the US military on captured models

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ORIGINAL: Symon


Oh, jeeze louize. You have always been a solid contributor, Vettim, and I admit I was laying in wait for that argument. I’m sorry you were the one who got caught in the salvo. You don’t deserve it. You were just … handy

Yes, much data was taken in the ’42, ’43, ’44 time frame, and a lot of it wasn’t published till post war (with actual publication dates). But looking at the contemporary tests, it’s pretty clear that the IJ engines were tuned and run at their war standards. MAP was set at exactly what the engine called for, and CAT was taken from the gauge marks and control stops – meaning that it’s nonsensical to presume a different fuel. That would require changing everything and make the tests useless, as a result for comparison purposes.

There are a lot of apocryphal data, about the planes, from certain pilots. This is understandable. It mirrors exactly the flight tests and field modifications to the P-38 series. Pilots like Sakae could, and did, push the envelope; running the throttles past the stops, accepting the higher CAT and noting the resultant MAP and use what they “experience” effectively. The long, over-water, flight from Taiwan to the Philippines, was possible because it was tested, by experienced pilots, and it was found that within a certain regime, you could lean-out hard and to heck with CAT. Way outside the standard regime.

Knowledgeable pilots knew this and could push their planes beyond the set, standard, limits – presumably having access to good mechanics when they return home. So, Sakae giving a 346 mph rating to a Model-21 in overboost, is entirely reasonable. But how many Model-21 pilots knew what Sakae did? And since the IJA arbitrarily drafted all the mechanics, welders, shipyard workers, mechanical fitters (i.e., every stinking skilled craftsman in Japan), as privates, it’s no wonder that good old Suki Sakamoto had a chief mechanic that was better at steaming soybeans than he was at tweaking engines.

Sigh …

Soon as the war hit, everything went to crap. Japanese didn’t know that, at the time, but it’s obvious to us in hindsight. Lots of very good designs, but absolutely nothing to back them up with. Japan was literally a “one trick pony” and as soon as you move the barrel, she was toast.

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ORIGINAL: JeffK
Interesting article about the other end of the spectrum, increasing the octane rating able to be used by USAAF/RAF fighteres in 1944-45

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

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ORIGINAL: mike scholl 1
One other point, John. By 44-45 production standards had slipped so badly that almost half the A/C engines being produced had to be rejected outright. Given the critical need, you can extrapolate that even those being accepted were probably a mixed lot...., with uneven capabilities. If pilot got one that was built right, he had a very capable A/C. If not, he was never going to get the promised and designed performance out of it.

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ORIGINAL: Symon

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ORIGINAL: JeffK
Interesting article about the other end of the spectrum, increasing the octane rating able to be used by USAAF/RAF fighteres in 1944-45

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

That’s an excellent summary article. The results certainly show significant improvement. I read it through several times, as well as the eleven others referenced within. The other articles tell the story of the months of iterative testing it took to get to those improved performance specs, and what had to be done to the engines in order to actually achieve those numbers.

Depending on the plane, MAP went from 52-56”, through the 64” range, and up to 70” in some cases. CAT saw a corresponding increase. It required changes to injection (#12 to #13 ports in most cases), changes to mixture control, changes to ducting for cooling (sometimes a new cooling system), changes to turbo speeds, with consequent changes to lo/hi blower transitions, Woof !!

A real eye-opener was the practical testing done on the early P-38s. Allison had a hard spec on the engine, 45C CAT and *maybe* 55C at 5-min WEP: exceed it and the engine turns into slag. But practical tests ran CAT to 85C without blowing it up. Pressure is Temperature, so higher T allows higher P, and HP can go up. That’s why the apocryphal stories of P-38 mechanics tuning their planes into monsters.

They were true but they were true for squadrons here and there that had knowledgeable commanders and righteous mechanics. Your run-of-the-mill P-38 pilot shows up with his copy of The Book and squadron practice makes that the basis for flight profiles. Obviously, some can perform better and do so. Sounds exactly like Sakai and Genda. But it wasn’t the “uniform” paradigm.

But alas … we had captured enough wartime documentation to know exactly how to run the various Japanese engines, according to their own specifications, so that’s exactly how we tested them. It’s what one would expect in a wartime situation, when one wishes to know the “capability” of an enemy aircraft for the edification of it’s pilots.

So, if one reads the “text” of the US test reports, one can get an appreciation of the what’s and wherefores of the results, including the engine operational conditions.

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ORIGINAL: Symon

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ORIGINAL: mike scholl 1
One other point, John. By 44-45 production standards had slipped so badly that almost half the A/C engines being produced had to be rejected outright. Given the critical need, you can extrapolate that even those being accepted were probably a mixed lot...., with uneven capabilities. If pilot got one that was built right, he had a very capable A/C. If not, he was never going to get the promised and designed performance out of it.

Yes, I konw Mike. That is the trap that hewing to IRL sucks us into.

Yes, I know that Japan had serious problems doing anything. But ... this a wargame, and there's certain paradigms that pertain to wargames. The most basic is that one must look to capability. So no matter who gets whacked IRL, it's a matter of could'a. This is a computer game. It knows nothing about the Thatch Weave, B&Z va T&B tactics, or any of that. I mean even the dinky-winky air war people can't get it right, so what's a boy to do with an abstract algorithm?

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ORIGINAL: mike scholl 1

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ORIGINAL: Symon

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ORIGINAL: mike scholl 1
One other point, John. By 44-45 production standards had slipped so badly that almost half the A/C engines being produced had to be rejected outright. Given the critical need, you can extrapolate that even those being accepted were probably a mixed lot...., with uneven capabilities. If pilot got one that was built right, he had a very capable A/C. If not, he was never going to get the promised and designed performance out of it.

Yes, I konw Mike. That is the trap that hewing to IRL sucks us into.

Yes, I know that Japan had serious problems doing anything. But ... this a wargame, and there's certain paradigms that pertain to wargames. The most basic is that one must look to capability. So no matter who gets whacked IRL, it's a matter of could'a. This is a computer game. It knows nothing about the Thatch Weave, B&Z va T&B tactics, or any of that. I mean even the dinky-winky air war people can't get it right, so what's a boy to do with an abstract algorithm?

True John. About the only thing I can think of that might be doable AND reflect reality would be to require 1.5 engines for each single engine A/C the Japanese build during 44-45, and 3 engines for each twin-engined A/C. Would at least pay lip service to their production woes...

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ORIGINAL: Symon

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ORIGINAL: JeffK
Interesting article about the other end of the spectrum, increasing the octane rating able to be used by USAAF/RAF fighteres in 1944-45

http://www.wwiiaircraftperformance.org/150grade/150-grade-fuel.html

That’s an excellent summary article. The results certainly show significant improvement. I read it through several times, as well as the eleven others referenced within. The other articles tell the story of the months of iterative testing it took to get to those improved performance specs, and what had to be done to the engines in order to actually achieve those numbers.

Depending on the plane, MAP went from 52-56”, through the 64” range, and up to 70” in some cases. CAT saw a corresponding increase. It required changes to injection (#12 to #13 ports in most cases), changes to mixture control, changes to ducting for cooling (sometimes a new cooling system), changes to turbo speeds, with consequent changes to lo/hi blower transitions, Woof !!

A real eye-opener was the practical testing done on the early P-38s. Allison had a hard spec on the engine, 45C CAT and *maybe* 55C at 5-min WEP: exceed it and the engine turns into slag. But practical tests ran CAT to 85C without blowing it up. Pressure is Temperature, so higher T allows higher P, and HP can go up. That’s why the apocryphal stories of P-38 mechanics tuning their planes into monsters.

They were true but they were true for squadrons here and there that had knowledgeable commanders and righteous mechanics. Your run-of-the-mill P-38 pilot shows up with his copy of The Book and squadron practice makes that the basis for flight profiles. Obviously, some can perform better and do so. Sounds exactly like Sakai and Genda. But it wasn’t the “uniform” paradigm.

But alas … we had captured enough wartime documentation to know exactly how to run the various Japanese engines, according to their own specifications, so that’s exactly how we tested them. It’s what one would expect in a wartime situation, when one wishes to know the “capability” of an enemy aircraft for the edification of it’s pilots.

So, if one reads the “text” of the US test reports, one can get an appreciation of the what’s and wherefores of the results, including the engine operational conditions.

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ORIGINAL: Symon

Ok, Japan is mostly done. Will send files to John 3rd for eval.

Ciao. JWE

Member: Treaty, Reluctant Admiral and Between the Storms Mod Team.

Reluctant Admiral Mod:
https://sites.google.com/site/reluctantadmiral/