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XyZspineZyX
07-17-2003, 02:41 PM
Question. I've read that teh Hurricanes & other lend-leae planes were not designed to run on the 77 octane full the soviets were using & that this soon caused engine performance to suffer . Furthermore, the engines became unreliable, which would have made the pilots not a bit happy. Can someone provide more information /clarify this for me ?

Was 77 octane standard for the CCCP throughout the war?

Thanks.

http://www.ciudadfutura.com/aviones/yak-1.jpg

"Anytime you have an opportunity to make things better and you don't, then you are wasting your time on this earth." -Roberto Clemente

XyZspineZyX
07-17-2003, 02:41 PM
Question. I've read that teh Hurricanes & other lend-leae planes were not designed to run on the 77 octane full the soviets were using & that this soon caused engine performance to suffer . Furthermore, the engines became unreliable, which would have made the pilots not a bit happy. Can someone provide more information /clarify this for me ?

Was 77 octane standard for the CCCP throughout the war?

Thanks.

http://www.ciudadfutura.com/aviones/yak-1.jpg

"Anytime you have an opportunity to make things better and you don't, then you are wasting your time on this earth." -Roberto Clemente

XyZspineZyX
07-17-2003, 03:27 PM
I'm not sure what the different octanes where, but it is true that the western engines where designed to run on a finer quality of aviation fuel. The Russians used a more "corse" grade of fuel (due to it being easier and quicker to make), which played hell with the less sturdy western designs.

The Russian Design philosphy calls for easy to manufacture stuff, thats why when the Germans where over-running major industrial areas, the Russians where still able to transfer production to other facilites with ease.

Rageman - Living up to his name.

XyZspineZyX
07-17-2003, 03:35 PM
Higher octane fuel:

I'll use a car engine for an example, since that's what most people are familiar with. No an automotive engine is not identical to an aircraft engine. But internal combustion processes are the same. I've built both aircraft and auto engines, by the way.

In a car, you have no doubt heard of "knock and ping". Maybe on a hot day, while trying to accelerate up a hill, you have even heard the engine in your car make a weird noise, like maybe a hundred little hammers were playing a symphony. This is detonation. Essentially, hotspots on the pistons are igniting unburned fuel, but not on the stroke of the engine they should be doing this. Higher octane helps fight this, as does less mechanical advance. Detonation hurts performance by trying to hammer a piston down, when it should be on it's exhaust stroke, for example. the higher octane will help all the fuel get burned on combustion, so that there's less unburned fuel to get ignited by a hotspot and cause detonation. Detonation can and will blow a hole in a piston.

What this means is that a high performance engine would have to be "de-tuned" to avoid this when using less octane, because even if you can't hear the pinging, it can still be present.

XyZspineZyX
07-17-2003, 03:58 PM
To elaborate on the above post some:

Gasoline is primarily made of hexane and octane hydrocarbons. Hexane burns faster and hotter which gives you much more energy or power per unit of time than octane. However high compression engines will knock or ping when running high percentages of hexane because the hexane will ignite before the piston is completely into the power stroke.

Octane burns slower and cooler and increasing its percentage prevents knocking and therefore engine damage. The power gained by higher compressions outweights the power lost by the decrease in hexane in the fuel.


So in conclusion for you daily life, use the fuel rating stated in your auto's manual because you do not get any more power or milage from higher rating than contrary popular belief.

http://www.redspar.com/redrogue/CraggerUbisig.jpg

About after 30 minutes I puked all over my airplane. I said to myself "Man, you made a big mistake." -Charles 'Chuck' Yeager, regards his first flight

XyZspineZyX
07-17-2003, 04:22 PM
I just love the anwers I get here sometimes!More than I expected for sure. Now I think from what you've said that the lower octane would mean less power from the engine. Especially if the engine was not adjusted to run on the lower octane fuel?

If so, is this modelled in FB ?(just curious)

Did merlins suffer more than allisons for example ?

Did the Soviets increase the quality of their fuel during the course of the war ? I've heard that high octane fuel became scarce in Germany as the war wore on.

Any info on German fuels would be interesting also.

Again, Thank you for the education!


http://www.ciudadfutura.com/aviones/yak-1.jpg

"Anytime you have an opportunity to make things better and you don't, then you are wasting your time on this earth." -Roberto Clemente

XyZspineZyX
07-17-2003, 05:46 PM
Saburo,

You cannot obtain any performance increases by using higher-octane fuel in the engines not designed for use of this fuel. But as been said here - performance of the engine designed for higher-octane fuel would suffer if lower octane fuel is used.

The lowest grade of Russian aviation gasoline was B-78 (octane number 78)
Russians produced large quantities of it, roughly more then 1 million tons every year of the war (little less in 1942) and received 2.8 million short tons of high-grade gasoline (most - octane number of 100) from US and GB via lend-lease during the war.

Russians some sporadic shortages of gasoline during the war, but nothing compare to difficulties Germans were facing. They have plenty of higher-grade gasoline for comparatively small number of the lend-lease planes and late war Russian planes which required it.

Unreliability of the Allison and Merlin engines were mostly related to very harsh Russian climate and use of the aircrafts with those engines from unprepared airfields (difficulties maintaining those engines in a primitive field conditions existing in Eastern Front).

That was one of the reasons Spitfires were relegated to primarily Air Defense duties and were based on airfields around big industrial centers in Russia. Of course, its very good high altitude performance being primary reason.


AKA_Bogun

---------------
The difference between fiction and reality? Fiction has to make sense.

- Tom Clancy

---------------
Ilsa: "That was the day the Germans marched into Paris."
Rick: "Not an easy day to forget. The Germans wore grey, you wore blue."
Ilsa: "Yes. I have put that dress away. When the Germans march out, I'll wear that dress again."

- Casablanca, 1942


Message Edited on 07/17/0301:49PM by Bogun

XyZspineZyX
07-17-2003, 06:38 PM
Wow, the knowledge of some forum members is really amazing!

Only one question for Bogun: what is a "short ton"?

Cheers,
Cold_Gambler

XyZspineZyX
07-17-2003, 06:48 PM
I imagine it is imperial measure unit.
There is a "short ton" - 2000 lbs.
There is also a "long ton" - 2200 lbs.

2,850,500 short tons of aviation and light-fraction gasoline equal 2,586,000 metric tons.

All numbers taken from here:
http://militera.lib.ru/research/sokolov1/04.html


AKA_Bogun

---------------
The difference between fiction and reality? Fiction has to make sense.

- Tom Clancy

---------------
Ilsa: "That was the day the Germans marched into Paris."
Rick: "Not an easy day to forget. The Germans wore grey, you wore blue."
Ilsa: "Yes. I have put that dress away. When the Germans march out, I'll wear that dress again."

- Casablanca, 1942