Octane rating

[Nikademus]

i prefer to admire the acrobatics from the ground myself. [:)]

[PaxMondo]

ORIGINAL: JWE

They exist, but they are hanger queens. Oh, too bad..

If you go around to small FOB's in the West, you'll still see lots of them. Anything built prior to about '72 according to my in house expert (I'm not, but I sit next to people who are). I just checked and the Conquests we fly have both. They date back to the 60's, but still a very nice plane. We're slowly replacing them with King Airs, only because the engine costs are killing us. $250K every time we need to replace one. King Air only runs us about $80K. Big difference. Otherwise, we much prefer the Conquests. Faster, easier to load (double cargo door and lower to the ground), but narrower body so not as roomy.

[geofflambert]

ORIGINAL: Historiker

[:)]
I didn't try to offend, either! You were only the unlucky one to hear my first expression of annoyance about this common habbit in this forum.

Habbit, is that a hybrid between a hare and a rabbit, or between a hare and a VW?

-- The Troll

[geofflambert]

Geez, after reading all that my head is really spinning. Where do all you guys come from?
Without starting my own thread, What I want to know is what was the regulation toenail length for US Marines? Anyone?

ORIGINAL: vettim89

Waiting for it ................

[wdolson]

ORIGINAL: JWE

ORIGINAL: PaxMondo
They exist, but they are hanger queens. Oh, too bad..

If you go around to small FOB's in the West, you'll still see lots of them. Anything built prior to about '72 according to my in house expert (I'm not, but I sit next to people who are). I just checked and the Conquests we fly have both. They date back to the 60's, but still a very nice plane. We're slowly replacing them with King Airs, only because the engine costs are killing us. $250K every time we need to replace one. King Air only runs us about $80K. Big difference. Otherwise, we much prefer the Conquests. Faster, easier to load (double cargo door and lower to the ground), but narrower body so not as roomy.

I'm most familiar with military aircraft of the WW II era. From what I've read, it was pretty common for experienced pilots to play with these settings. That's how the 5th AF was able to stretch P-38 missions from 5 hours to 8. Lindberg taught them how to set the engine right on the ragged edge to get the most out of their fuel. I believe the Japanese were quite surprised when P-38s started showing up hundreds of miles deeper into their territory than ever before.

I have only theoretical knowledge about this stuff, Pax, you're the expert since you've actually done it. There is a big difference between just reading about something and actually doing it.

Bill

[JWE]

ORIGINAL: wdolson
I have only theoretical knowledge about this stuff, Pax, you're the expert since you've actually done it. There is a big difference between just reading about something and actually doing it.

Bill

Me too. I just fly little dinky puddle jumper airplanes. Pax flys the big ones. There is a biiiiiig difference. Remember once, 40 years ago, when Dad rented a Beech twin and picked me up from Orlando and flew us home to Tampa. All he wanted was a bit of twin time for his log book. To this day, I remember. The Log pilot went to sleep in the back, so it was me and Dad in the cockpit. It was like doing something wonderful with your Dad. It was exceptional. We went up towards Ocala, and then banked left towards Homosassa. Went low over the coast, and took an Easterly over Tarpon Springs. Went roughly around Thonotosassa and popped back home from an Apollo Beach vector.

To this day, when I think of it, I cry. It's dark, but there's bright stuff out the window. There's lights, there's places where people live, there's life down below us. And I'm in a dark cockpit with a thing on my head and Dad says "See all that?" "Yes, Sir" "What do you see, John?"

Maybe it was satori, don"t know, but I remember every detail of that time. Know everything that was on the panel. Know every light that was out the window. Remember his profile and every bit of clothing he was wearing. And remember his warm voice in my phones, "What do you see, John?" Woof !!

[Erkki]

Also one must remember that performance of an aircraft also depends on altitude. There is only one altitude for best speed, another for engine power, a third for climb, somewhere between these a fourth for shortest turning time, best acceleration etc. The altitude of best range is close to the altitude of best level speed, only slightly lower or higher.

That is actually very high for most WWII fighters, for example 7600m or about 25,000 feet for P-51, and about 18-21000ft for most Spitfires, Bf 109s, Fw 190s and even the Zeros. That could make mission planning difficult especially for bombers, as more often than not the optimum altitude would not be the attack altitude, or the altitude the enemy would be expected to use. I believe the in-game much increased OPS losses and pilot fatigue(also possibly aircraft fatigue?)when using extended range simulates these problems and things going wrong more often than usually for the pilots, when it comes to stuff like engine life and fuel and oxygen use, pretty well.

[PaxMondo]

ORIGINAL: Erkki

I believe the in-game much increased OPS losses and pilot fatigue(also possibly aircraft fatigue?)when using extended range simulates these problems and things going wrong more often than usually for the pilots, when it comes to stuff like engine life and fuel and oxygen use, pretty well.

I agree. I think the game does a pretty dang good job on this as well.

[inqistor]

I was seeking information about experiment with fitting 37mm Tank Gun on DINAH, and accidentally found something about avgas, in Tuluvu wreck reports:

TONY No. 263 was found on No. 1 or the old strip. Although MPMR says it was assessed unserviceable on August 4th, 1943, the pro-forma report estimated that it had landed and not been moved for three weeks to a month (prior to January 2nd, 1944). A recent flood had submerged the aircraft up to the lower part of the wing. It was painted mottled green on upper surfaces and unpainted on lower surfaces. The engine was No. 252, dated March 1943. Two 12.7mm machine guns and two 7.7mm guns were fitted. Ammunition was armor piercing-tracer and high explosive. Fuel rating was 92 octane.

So, it seems, 92 Octane was standard for Japan.

[mdiehl]

It was not the standard though. The Japanese, like the USA, produced avgas with several different octane ratings. The Tony needed 92 octane because it's engine was a derivative of the German DB-61 in-line. The USA had designs that ran on automotive gasoline, but they were not high peformance designs. The Piper J3 used for light transport and artillery observation for example was designed to run on 80 octane fuel.

[Treetop64]

Germany was rather forced to use synthetic, due to the fuel situation they faced. Don't know if it was actually "better".

[Buckrock]

ORIGINAL: inqistor
So, it seems, 92 Octane was standard for Japan.

I got the impression that 92 octane was the desired standard but not always the reality due to low production and later, a plague of submarines.

[21pzr]

Been following this for a couple of days. Funny how people think that higher octane equates to higher energy. Octane is a measure of ignition delay. The higher the octane, the longer the fuel takes to ignite. Gasoline, whether produced in the 40's or now, has a fairly small range of "specific energy", or the amount of energy released per gallon (liter, cubic meter, or pound). As others have stated, you only benefit from higher octane if you have a high enough compression ratio. I can remember back to my younger days of tinkering with muscle cars in the 60's and 70's, and having a tricked out Dodge hemi that would knock on any fuel other than Sunoco Ultra, which was a 95+ octane. This is why many people pay too much for gas in their cars, buying premium, with its higher octane, when their engine doesn't need it. Premium does not give you any more horsepower per gallon than regular.

The other track of this thread, that of leaning out fuel mixtures, or retarding spark timing is really reminiscent for me as well. Changing timing on airplane engines as JWE and Pax mention is great for optimizing your engine to whatever fuel you bought that day. The reason most planes don't have this anymore is the much more uniformity of avgas than was the case in WWII. I mean, come on, floating drums of avgas ashore (water contamination and salt), straining through chamois! Again, anyone who worked on the old muscle cars knows as Pax does about leaning out the mixture. Much of the gasoline used by a carbureted engine is not used to provide power, it is used to absorb heat while evaporating in the cylinder, to keep the fuel/air mixture cooler, helping the tetra-ethyl lead octane booster to keep the fuel from igniting too soon, preventing knock and loss of power. Not to say that the fuel didn't burn, but that "excess" fuel plus timing meant that much of it was burning while the piston is already going down, so little energy is transferred to the propeller. This is what makes water injection so effective. The old Indy cars with the Offenhouser engines used a massive turbocharger, ran a very lean fuel mixture, and used water injection. It was really funny to see these cars with a fairly small engine running at 200 mph until the turbo blew, and then they could only do about 40mph! Methanol is used today as both an oxygenator (less pollution) and an octane booster, since no one really wanted all the lead dioxide fumes in the air that we had before unleaded gas. As Pax says, it cools the mixture, alcohol burns slower than gasoline, and the burning adds its own energy.

As a 35 year merchant ship chief engineer (all diesel time, sorry, steamboateng), and a tankerman, I will add my $.02 to Steamboat's comments about crude and bunker. "Sweet" and "Sour" crude refer to the sulfur content (hydrogen sulfide having a rotten egg smell, hence sour). Metallic sulfur does contribute to engine wear, but the most damaging aspect of sulfur in fuel is that when it is burned, the sulfur dioxide produced will combine with the water vapor also produced, and at low exhaust temperatures will condense as sulfuric acid, which will really accelerate your engine wear. One point that Steamboat didn't mention about Bunker oil is that while the density is different between Bunker-C and Navy Special, the real difference is that Navy Special has a lower viscosity (thinner) than Bunker-C, which allows for the lower heating before burning in the boiler. The navy was interested in reducing auxilliary equipment (less heating equipment), and using less steam to heat fuel and more steam to power the propeller.

Bill

[Buckrock]

Actually after a bit of checking I should probably qualify my previous comment.

Around the time the Japanese opened proceedings at Pearl Harbour, a decision was taken that for the immediate future, the supply of aviation fuel for Japanese combat aircraft would be in the range of 87 to 92 octane.

So even from the start of the war it sounds like there may not have been a specific service standard but rather a band of standard fuels from which it was hoped the most appropriate fuel in that band would be available in sufficient quantities for the right aircraft.

If anything then, it may only have been at the unit level that any specific standard for aviation fuel was applied, being determined perhaps by the aircraft type and model being operated. In theory anyway.

I wonder how that decision at the end of 1941 to supply no fuel with a higher octane rating than 92 would have been received at Nakajima. At that time they'd just started development testing of the Homare, an engine designed on the assumption that Japanese aviation would soon have access to 100 octane fuels.

The glossy sales brochures at Nakajima Corporate must have been stained with tears that day.

[steamboateng]

21pzr, glad to make your aquaitance sir.
I got plenty of diesel time, I've crawled up more Sulzer intake and exhaust trunks than I care to think about.
Not to speak of the comforting warmth and lube oil shower when entering a crankcase several hours after FWE!
Thanks for the reminder about the formation of sulfuric acid. Been retired for 10 years.......

[Mac Linehan]

ORIGINAL: Historiker

That's one of the great things about this game. With it's avarage player age of well above 40, the combined knowledge through experience and education is astonishing.
Just imaging asking such a qeustion in a "Counterstrike" or "Battlestations Midway" forum... [:D]

Gents -

I have really enjoyed the discussion on this fascinating topic; you are all very well informed - in many different ways.

As an interesting side note:

My father, John C. Linehan (1901 - 1969) worked in South America from 1939 thru 1961.

As he passed away while I was a Sophomore in High School (age 16), I regret that I was not old enough to have the interest to speak at length with him about his life or profession. Dad worked for Creole Petroleum, and was in charge of the fleet of motorboat tankers that transferred crude oil from the Lake Maracaibo oil derricks to shore for processing. We lived in Campo Verde, Tia Juana, one of the Creole housing camps. Dad retired in 1961, our family moved to Eichler Highlands California in the Bay Area.

To change subjects slightly -

Once retired, my father had a desk with a glass top, under which he had numerous photographic memento's taken during his time in South America. Two of the photos I still have in my possession. Both pictures are of the burning wreck of a warship that has been scuttled in shallow water; I am certain that it is the Graf Spee - very shortly after she scuttled. In the foreground are a mass of spectators crowded on a pier, the Graf Spee is a short distance away in the background. Both photos are undated on the back, but were originally scalloped along the edges - as was common for photos of that era. My sister inadvertently trimmed the scalloping when she came across the pictures upon my return from Desert Storm in 1990. However, the actual photos (black and white) are unaltered.

While there is no way of determining if Dad took the photos himself, I am guessing that he did indeed do so, and thus they were prominently displayed on his desk top. It would have been interesting to hear his story and how he came to be in Montevideo Uruguay on 18 December, 1939.

My intent is to purchase a scanner and post the two photos on this website. I am not sure if they have been previously published, but suspect not.

OK - strayed enough off topic; but have learned much and am looking forward to more!

Mac