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RE: Airplanes - 9/26/2013 3:54:46 PM   
castor troy


Posts: 14330
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From: Austria
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quote:

ORIGINAL: Big B

Interesting discussion (and I do fall into the 'US fighters used higher octane' camp.)

However, one thing I remember from 30+ years ago in my hot-rodding days, was that running higher octane fuel in a lower compression engine designed for lower octane fuel - actually hurt performance. As I recall you need higher compression to reap the benefits of higher octane fuels.

I readily admit that I have no experience with turbo/supercharged engines, however I do remember that if you go turbocharging or supercharging a stock lower compression engine - what ever gain you achieve will quickly destroy the bottom end of that engine because the crank, rods, rings, and bearings will not handle the boost....without seriously strengthening all of those components (not to mention modifying the oil pick-up, windage, and head-flow).

I may be all wet, but it seems to me that running significantly higher octane fuel without increasing compression is kinda worthless - and if you do increase compression - you MUST increase the robustness of the entire bottom end or it the engine will self-destruct quickly....so I'm not sure what good it would do to run 100+ octane avgass in a 90 octane designed engine?...it doesn't seem to make practical sense to my Neanderthal brain?
On the other hand, I may be completely wrong

quote:

ORIGINAL: Symon


quote:

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.






dunno about the '40s but nowaday's engines don't care. We used to drive cars using 90 Octane fuel that isn't even available on most petrol stations nowadays. So we go with 95 Octane fuel. Now Shell is promoting to use 100 Octane fuel (which is just horrible more expensive), saying it would get you more performance out of your crappy car and being better for it anyway, whatever that means. There also has been 98 Octane fuel as long as leaded fuel was allowed which then vanished and if you had a car using that you had to get 95 Octane fuel and fill in a litre of lead substitute.

< Message edited by castor troy -- 9/26/2013 3:56:56 PM >

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Post #: 61
RE: Airplanes - 9/26/2013 5:51:36 PM   
Symon


Posts: 1928
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From: De Eye-lands, Mon
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quote:

ORIGINAL: John 3rd
I'm go regardless of things.

John: I will need you to also work the additional ZERO variants we've created for RA.

You did get the RA files I sent--correct?

Yep, got them. Suddenly dawned on me, when reading this, that you guys have some different airplanes. Oops. Have to do a sanity check with your airplane file.

Okey dokey, then. JWE

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Post #: 62
RE: Airplanes - 9/26/2013 6:42:17 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		@ Castor Troy, and @ BigB,
Yeah, everything you guys said. The "octane" rating of a fuel is just a measure of its anti-detonant properties. Fuel, is just "fuel" and its specific heat depends on the blend of specific cracking temperature fractions. 87, 90, 100 "octane' fuel has the same specific heat/ml. They just have different anti-detonant properties. "Octane" is just the ratio of the octane molecule to the heptane molecule. Octane requires a few more KCal/Mole to "burn" than heptane, but the energy release is insignificantly different.

So you got gas and you burn it and the manifold heats up and the cylinder heads glow red hot and after a while, you don’t need compression and a spark to initiate the power cycle; engine heat (and a skoosh of compression) is enough to pre-detonate the fuel. So what to do?

Well, you increase the octane ratio and when that isn’t enough you add things like TEL, or bromines, or benzene/nitrile things, anything that won’t change specific heat, but will shift the detonation temp. Doing that lets you run a motor at a higher temp. That means a higher intake pressure (P ~ T). That means a higher engine RPM. That means a higher sustained power output. It’s basic P-chem, PV=NRT.

And then you get turbos and other such, but the basic physics and P-chem is the same. Fuel is fuel, and additives are just there to adjust things to account for heat (the big T). “Octane” ain’t power.


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Post #: 63
RE: Airplanes - 9/26/2013 9:34:31 PM   
Big B

 

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From: Old Los Angeles pre-1960
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quote:

ORIGINAL: Symon

@ Castor Troy, and @ BigB,
Yeah, everything you guys said. The "octane" rating of a fuel is just a measure of its anti-detonant properties. Fuel, is just "fuel" and its specific heat depends on the blend of specific cracking temperature fractions. 87, 90, 100 "octane' fuel has the same specific heat/ml. They just have different anti-detonant properties. "Octane" is just the ratio of the octane molecule to the heptane molecule. Octane requires a few more KCal/Mole to "burn" than heptane, but the energy release is insignificantly different.

So you got gas and you burn it and the manifold heats up and the cylinder heads glow red hot and after a while, you don’t need compression and a spark to initiate the power cycle; engine heat (and a skoosh of compression) is enough to pre-detonate the fuel. So what to do?

Well, you increase the octane ratio and when that isn’t enough you add things like TEL, or bromines, or benzene/nitrile things, anything that won’t change specific heat, but will shift the detonation temp. Doing that lets you run a motor at a higher temp. That means a higher intake pressure (P ~ T). That means a higher engine RPM. That means a higher sustained power output. It’s basic P-chem, PV=NRT.

And then you get turbos and other such, but the basic physics and P-chem is the same. Fuel is fuel, and additives are just there to adjust things to account for heat (the big T). “Octane” ain’t power.


Right - so if you're not increasing compression - you don't need higher octane fuel, to burn cooler and forestall pre-detonation.

@ Castor: in the pre-computerized engine days, if you ran 104 octane premium gas in a low compression 87 octane rated engine - you would simply foul the plugs (along with paying too much for gas).

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Post #: 64
RE: Airplanes - 9/27/2013 4:26:55 AM   
PaxMondo


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quote:

ORIGINAL: Symon
@ Castor Troy, and @ BigB,
Yeah, everything you guys said. The "octane" rating of a fuel is just a measure of its anti-detonant properties. Fuel, is just "fuel" and its specific heat depends on the blend of specific cracking temperature fractions. 87, 90, 100 "octane' fuel has the same specific heat/ml.


OK, I'll agree with you here within the scope of the games abstractions. There are differences, alkanes in general will have slightly higher specific heat than equivalent alkenes due to their structures (which is in fact why they "burn" slower). Emphasis is very much on the slightly and as I say, within the abstractions that we are dealing it is an acceptable assumption.

I bring this up only because back in the 40's high octane was generally made by alkylation, not cracking. It the opposite process. So back in the 40's/50's you could use high octane gas as a safe solvent, just like paint thinner today. Today's gasoline is HIGH in benzene (amoung other known carcinogen's) as it is primarliy from a cracking process (generally FCC) and I don't even recommend standing within 'sniff' range when filling your auto.

The upshot is that back in the 40's higher octane fuel also had a little more specific heat. Today, higher octane may have the same, or even slightly lower. Again, within the abstraction of the game, this is all pretty much moot.

The real benefit that the allies gained with high octane fuel was they would avoid WEP. Logistically this is huge. Instead of having to have TWO or potentially THREE fuel sources for each aircraft, they only needed one.* That's a HUGE savings.


* AvGas, Methanol, Distilled Water. Methanol could be pre-mixed but it is hygroscopic and hard to store/maintain. Since the proportion is rather critical, it is generally mixed just prior to filling. At least that's what we did back in the "old days" of dirt track racing. Not sure how they handle it now ... but my old days would be far closer to the realities of 1942 than 2013 would be.

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Post #: 65
RE: Airplanes - 9/27/2013 7:20:56 PM   
Symon


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From: De Eye-lands, Mon
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quote:

ORIGINAL: Big B
Right - so if you're not increasing compression - you don't need higher octane fuel, to burn cooler and forestall pre-detonation.

@ Castor: in the pre-computerized engine days, if you ran 104 octane premium gas in a low compression 87 octane rated engine - you would simply foul the plugs (along with paying too much for gas).

This is so true. I am become an avid Light Sport Aircraft enthusiast and am learning more about the generally available 87 and 91 "octane" fuels that I ever wanted to know. The Navy guys turned me on to a couple of "local" stations that have pumps for 92 grade, ethanol free, unleaded. Been using that in the Harley for almost a year. Am researching planes and engines (gonna buy one, soon) and find dire warnings about using Auto-gas, hidden away in the tech-specs. Exactly like PaxMondo suggests, ethanol content has caused many unplanned landings because of condensation fogging of the lines. The Navy guys told me to buy a good 5 gal jerrycan and when I fill up the bike (or the Jeep) fill up the can for the plane.

There's a very serious movement afoot to relabel airfield MOGAS and have refiners provide product that is safer for use, and forget the politically correct bull$hit. There's also a movement afoot to have a CAT gauge on the panel again. Many of the legitimate LSA manufacturers are rethinking their engine control monitoring techniques as a result.

I guess the only point to this is that gas ain't gas. There's this kind, there's that kind, and it all depends on the engine what kind works.

Ciao. JWE

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Post #: 66
RE: Airplanes - 9/29/2013 9:34:23 PM   
John 3rd


Posts: 17178
Joined: 9/8/2005
From: La Salle, Colorado
Status: offline 		John: Just got back from a quick family trip to KC. What is your status with this?

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Post #: 67
RE: Airplanes - 9/29/2013 11:39:06 PM   
PaxMondo


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Joined: 6/6/2008
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quote:

ORIGINAL: Symon
I guess the only point to this is that gas ain't gas.

In a nutshell, YES.

And today much moreso than in the 40's due to all the EPA requirements, additives for FI, CA specific requirements, yaddi yaddi yaddi ....

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Post #: 68
RE: Airplanes - 9/29/2013 11:47:42 PM   
PaxMondo


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quote:

ORIGINAL: Symon
ethanol content has caused many unplanned landings because of condensation fogging of the lines.

Even the IJ knew for aviation you MUST have separate AVGAS and WEP tanks in the aircraft. You cannot mix these two in an aviation setting. These are injected separately, best if directly into the combustion chamber.

The partial pressures of the two liquids and their respective miscibility curves are very much dependent upon temp and pressure. Mix in advance of flight and your engine will stop and likely not restart without removing the cylinger heads. At the very least you will need to pull the spark plugs to dry the cylinders out. Not much fun at 20,000 ft and 40 miles down range of your airport.

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Post #: 69
RE: Airplanes - 9/30/2013 9:55:45 PM   
Symon


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From: De Eye-lands, Mon
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quote:

ORIGINAL: John 3rd
John: Just got back from a quick family trip to KC. What is your status with this?

Jury duty. A horror show. Told them about Mom and they want Drs and Caregivers to file statements. Wrong !!! I thought I was being righteous and trying to get my sister Jennie to take Mom for a week, but circumstances got in the way. I said so and volunteered for a deferrment to the next term. But the system, here, is beyond Byzantine.

So I told them I would not be showing up and if they want to issue a warrant, that's their privilege. I'm a retired Cali Atty and have retained a local friend. to represent me. It would take him all of 20 minutes. And after he's done, I'm no longer eligible for the jury pool. A rather sad ending from my prospective, and certainly from Baldwin County's. But folks need to look at 'needs must', and not just their paperwork.

Might have to spend an hour in 'county'; there's no way in Hell I'm spending money for bail for this piece of ridiculousness. Golly, I'm getting all fired up again, like I used to. Woof !! This is gonna be fun. Being retired and doing what you want is pretty cool.

Ciao. John

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Post #: 70
RE: Airplanes - 10/1/2013 1:47:26 AM   
PaxMondo


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Status: offline 		TDF!!!





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Post #: 71
RE: Airplanes - 10/1/2013 8:36:12 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		Ok, still plugging away despite the mongrel bureaucrats nipping at my heels. Here’s a preview of IJN fighters, with USN planes for comparison. Notice several changes (in red).


Max Altitude is no longer “service ceiling”. It is an evaluation result somewhere between “combat” and “operational” ceilings. An altitude where a plane can actually do something.

Max Speed is more consistent. It is all given at Military power (max sustained power, at altitude, for at least 15 minutes). All the different kinds of WEPs are ignored, as being too different to allow for a consistent algorithm, as well as being individually limited as to time by injection fluid tank size and maintenance schedules.

Climb rate is again more consistent. It is a weighted average of initial climb rate and rates at the critical altitudes. Everyone is treated equally.

Maneuver is subject to a proprietary program of the Air Team. But, once again, consistency is paramount. Maneuver is subject to the standard engine performance specifications that generate Climb, Speed and Ceiling parameters. Must say (sorry, Ian, but it’s obvious by now) that Maneuver has a dependency on HP. You get a good plot of HP at Alt, you get a good number for comparative Maneuver.

You will see a lot of similarities with BigBs airplane data. Some departures, to be sure, but conceptually similar. You will also find the data working smoothly within the A2A combat algorithm. Despite what you may see on the main thread, A2A is a matrix of Speed, Climb, Maneuver, within the different bands. As planes approach unity, in the algorithm, pilot experience becomes paramount.

Ciao, JWE

Attachment (1)

< Message edited by Symon -- 10/1/2013 8:37:09 PM >

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Post #: 72
RE: Airplanes - 10/1/2013 11:35:47 PM   
Dili

 

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quote:

You get a good plot of HP at Alt, you get a good number for comparative Maneuver.


Not true. There are several fighters that employed same engine and were very different at altitude. Example DB 605 engine and Bf-109, Fiat G55, Reggiane 2005, Macchi205. The Macchi with much less wing loading was lousy at altitude but great at medium,low level. They then increased the wing size to get it better. G.55 and Re.2005 were the better ones. All same engine.

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Post #: 73
RE: Airplanes - 10/2/2013 4:11:09 AM   
PaxMondo


Posts: 9750
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Status: offline 		John,

Nice work here. Thanks for all your efforts.



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Post #: 74
RE: Airplanes - 10/2/2013 6:36:51 AM   
LoBaron


Posts: 4776
Joined: 1/26/2003
From: Vienna, Austria
Status: offline 		Wow JWE, you are moving along much faster than I thought. Number look interesting, although I do not have the skills to compare them to their r/l counterparts and what the A2A engine does with em.

That said, I at least partly agree with Dili.

The mvr value is, as you say, highly dependent on HP per alt. But equally important are airframe attributes, both for assigning the basic mvr value as well as how the performance curve looks at alt. The problem is that this value represents a pretty large ammount of variables all thrown together in a number.

P.S.: Did you consider looking at acceleration and divespeeds and the likes? For example Tbolts used a simple dive, or a split-s as an (at least in the PTO) unbeatable defensive move. Such specialities might influence mvr as well.

Or am I into too much detail for what you are aiming for?

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Post #: 75
RE: Airplanes - 10/2/2013 2:26:32 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		Howdy, Baron.

There’s a ton of airframe attributes that go into it. If you look at the data, you can see that there’s many planes with identical engines that have very different performance parameters.

One can get good numbers at specific points. Once you get them they form a functional constant and one can use a plane’s power curve to ‘fill in the blanks’ or determine the shape of the roll-off. Makes it smoother, and more consistent, although calling it smoothness is kind of silly for stepped bands at 10k intervals.

Don’t forget, this is for calculating values useful to the game engine. Not quite the same as irl.

Ciao. JWE


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Post #: 76
RE: Airplanes - 10/2/2013 4:03:42 PM   
oldman45


Posts: 2320
Joined: 5/1/2005
From: Jacksonville Fl
Status: offline 		This may be out to lunch and not apply at all, but I have a neighbor that flew hellcats late in the war and swears that they would out turn zero's by using the engine torque, is that for real and should/would it apply here?

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RE: Airplanes - 10/2/2013 4:08:50 PM   
LoBaron


Posts: 4776
Joined: 1/26/2003
From: Vienna, Austria
Status: offline 		Yep, sorry JWE. I assumed from your post you factored in airframe specs for initial mvr and completely relied on the HP/alt for the alt band curve.

Was pretty stupid to assume the Babes team would not take such stuff into account.



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Post #: 78
RE: Airplanes - 10/2/2013 7:42:41 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		We try, Baron, we try

Here's the IJAAF planes. Not all done, but mostly. Missing ones are the wierd exp stuff. Have to go to the crystal ball for that. The real witch is the Ki-100. The legitimate sources give reasonable specs for it, but they just don't quite jibe with Cd0 analysis given the planned engine HP. Think a lot of IJ wartime specs (faithfully reproduced by Francillon) were the product of what they had in hand at the time. And this was the time period of the T-42 Mod-2 fuel specifications. What could they have done with well built and well maintained engines using their everyday, ordinary, 1941-43 standard combat aviation fuel. The world wonders.




Attachment (1)

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Post #: 79
RE: Airplanes - 10/2/2013 7:56:51 PM   
Symon


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From: De Eye-lands, Mon
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quote:

ORIGINAL: oldman45
This may be out to lunch and not apply at all, but I have a neighbor that flew hellcats late in the war and swears that they would out turn zero's by using the engine torque, is that for real and should/would it apply here?

Could be real, don't know. Doesn't matter anyway. The game algorithm is a mathematically driven evaluation of performance characteristics of devices characterized as "airplanes". Planes are planes. They are nothing but a data box with technical parameters defined "relative" to one another.

J

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Post #: 80
RE: Airplanes - 10/3/2013 5:19:02 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		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


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Post #: 81
RE: Airplanes - 10/4/2013 12:48:05 AM   
Dili

 

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

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Post #: 82
RE: Airplanes - 10/4/2013 6:48:08 PM   
Symon


Posts: 1928
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From: De Eye-lands, Mon
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quote:

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

< Message edited by Symon -- 10/4/2013 7:02:06 PM >

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Post #: 83
RE: Airplanes - 10/5/2013 8:23:41 PM   
sandman455


Posts: 209
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From: 20 yrs ago - SDO -> med down, w/BC glasses on
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quote:

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.

_____________________________

Gary S (USN 1320, 1985-1993)
AOCS 1985, VT10 1985-86, VT86 1986, VS41 1986-87
VS32 1987-90 (NSO/NWTO, deployed w/CV-66, CVN-71)
VS27 1990-91 (NATOPS/Safety)
SFWSLANT 1991-93 (AGM-84 All platforms, S-3 A/B systems)

(in reply to Symon)
Post #: 84
RE: Airplanes - 10/5/2013 10:48:01 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		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


_____________________________

Nous n'avons pas peur! Vive la liberté! Moi aussi je suis Charlie!
Yippy Ki Yay.

(in reply to sandman455)
Post #: 85
RE: Airplanes - 10/5/2013 11:38:49 PM   
Dili

 

Posts: 4708
Joined: 9/10/2004
Status: offline 		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?

< Message edited by Dili -- 10/5/2013 11:42:01 PM >

_____________________________


(in reply to Symon)
Post #: 86
RE: Airplanes - 10/6/2013 4:29:55 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline
quote:

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


_____________________________

Nous n'avons pas peur! Vive la liberté! Moi aussi je suis Charlie!
Yippy Ki Yay.

(in reply to sandman455)
Post #: 87
RE: Airplanes - 10/10/2013 5:46:26 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline 		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

_____________________________

Nous n'avons pas peur! Vive la liberté! Moi aussi je suis Charlie!
Yippy Ki Yay.

(in reply to Symon)
Post #: 88
RE: Airplanes - 10/11/2013 3:15:31 PM   
oldman45


Posts: 2320
Joined: 5/1/2005
From: Jacksonville Fl
Status: offline 		Wow, what a gold mine you have found!!

_____________________________


(in reply to Symon)
Post #: 89
RE: Airplanes - 10/11/2013 6:16:59 PM   
Symon


Posts: 1928
Joined: 11/24/2012
From: De Eye-lands, Mon
Status: offline
quote:

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 !!!

_____________________________

Nous n'avons pas peur! Vive la liberté! Moi aussi je suis Charlie!
Yippy Ki Yay.

(in reply to oldman45)
Post #: 90
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