109 e3b against spitfire II

[Kurfürst]

Originally Posted by Seadog

RAFFC pilots also wanted better performance, and they got a complete transition to 100 octane fuel, a transition which was completed prior to the start of the battle.

Source please. Oh wait, we have your word for it, and everything it worth for.

Originally Posted by Seadog

Yet there isn't a single statement anywhere about RAFFC pilots complaining about the lack of 100 octane engines or fuel, during the Battle.

Originally Posted by Seadog

Fighter pilot don't give a damn about octane ratings except to get more power.

No comment

[Seadog]

Originally Posted by Kurfürst

Source please. Oh wait, we have your word for it, and everything it worth for.





No comment

We have a source:



and you have not presented a single shred of evidence to contradict it.

Originally Posted by Kurfürst

Quote:
Originally Posted by Seadog
Yet there isn't a single statement anywhere about RAFFC pilots complaining about the lack of 100 octane engines or fuel, during the Battle.
Quote:
Originally Posted by Seadog
Fighter pilot don't give a damn about octane ratings except to get more power.

No comment

Of course you have no comment. The whole point of 100 octane fuel was give engines more power through higher boost pressure, and no RAFFC pilot flying a Merlin engined fighter during the BofB is on record of complaining that he can't use overboost, and so was deprived of 30% more power than his buddy in another squadron.

[CaptainDoggles]

no RAFFC pilot flying a Merlin engined fighter during the BofB is on record of complaining that he can't use overboost, and so was deprived of 30% more power than his buddy in another squadron.

As I said earlier, absence of evidence does not imply evidence of absence.

Your source, if I remember from way back in the thread, is a 3rd-party book. I asked if they had references since this is not a primary source and you ducked the question.

[Seadog]

Originally Posted by CaptainDoggles

As I said earlier, absence of evidence does not imply evidence of absence.

Your source, if I remember from way back in the thread, is a 3rd-party book. I asked if they had references since this is not a primary source and you ducked the question.

I didn't duck it. We have a source that states that RAFFC went completely to 100 octane, and there is no source that states that this is incorrect, and there is a large body of evidence that supports the view that RAFFC used 100% 100 octane fuel operationally during the BofB. If you don't accept the above source, than present some evidence that from July 10 to October 30 1940, that even a single RAFFC Merlin powered squadron was using 87 octane during combat operations.

There was about 46 RAFFC Merlins engined fighter squadrons available on July 08 1940. Surely you can find evidence that one of them was using 87 octane operationally during the battle. Just one...

[Crumpp]

there is no source that states that this is incorrect,

Yes there is a primary source that refutes the secondary source you posted, Seadog.

The seventh conference on 18 May 1940 clearly states that certain units in Fighter Command will make the switch.

That document has been posted ad nauseum.

As this on going fuel debate....

The best source on German Aviation Fuels is the Fischer Tropsch Archives.

http://www.fischer-tropsch.org/

They have a good collection of documents online anyone can learn about German fuels. Allied Fuel and German fuels were not directly comparable.

B4 is slightly better than 87 grade Allied fuels and is roughly equal to 91/~115 octane.

C3 began as the equivalent to 100/130 grade allied fuels and was later improved to 100/140 grade which allowed such improvements as a straight manifold pressure increase without additional knock limiting performance enhancement to 1.62ata in the BMW801D2 series and 1.98ata in the DB605 series engines.

C3 was adopted in 1940 and was used during the BoB.



The whole debate is silly and pointless. The arguments are put forth by gamers to make their personal game play more enjoyable such that a game shape performance can overcome their own inadequacies. It is an agenda advanced by clowns who focus on whatever specific portion paints the desired picture without regard to the whole.

The facts are the German fuel was roughly equal but on the whole slightly inferior to the natural petroleum. The Allied fuels were better but allied engine technology could not take full advantage of their superior fuels. The German materials technology, chemical engineering, and fuel metering technology was much better and made up for the lower quality fuels.

Just the fact the Germans had direct fuel injection technology and the allies never did balances any fuel differences. One can make considerable power gains without changing fuel type just by changing the fuel metering system from a carburetor or Throttle Body Injection to Direct Injection. In a 1000 hp engine, you can expect to gain 80-150 hp just by changing the fuel metering method.

The whole debate ends up being a wash.

[Seadog]

Originally Posted by Crumpp

Yes there is a primary source that refutes the secondary source you posted, Seadog.

The seventh conference on 18 May 1940 clearly states that certain units in Fighter Command will make the switch.

and the accepted dates for the BofB are July 10 to Oct 30, 1940.

[Crumpp]

Seadog,

18 May 1940 is only 6 weeks from the start of the Battle of Britain.

The language in that primary source document refers to "certain units" and not "ALL" units.

Very importance difference.

[Viper2000]

Originally Posted by Crumpp

Just the fact the Germans had direct fuel injection technology and the allies never did balances any fuel differences. One can make considerable power gains without changing fuel type just by changing the fuel metering system from a carburetor or Throttle Body Injection to Direct Injection. In a 1000 hp engine, you can expect to gain 80-150 hp just by changing the fuel metering method.

The whole debate ends up being a wash.

Direct injection isn't necessarily the best approach.

If you're supercharging then putting fuel into the flow upstream of the supercharger will cool the flow by about 25 K due to the latent heat of evaporation of the fuel.

This considerably reduces the compression work required from the supercharger, which is equivalent to an increase in its polytropic efficiency.

I would suggest that the mixture distribution is likely to be pretty good downstream of the supercharger under design conditions, because the fuel is completely evaporated.

Direct injection will obviously achieve better mixture distribution at low rpm where the supercharger delta H isn't sufficient to guarantee that all of the fuel is evaporated. So DI will give you better performance close to idle. This is very important for car engines, but not so much for aeroplanes.

Furthermore, as you develop your engine and increase the amount of supercharge, you'll tend to cruise higher. Even at constant boost, you'll see a higher supercharger delta H and higher charge temperature, which makes the advantage of adding fuel upstream of the supercharger more important.

It's also much easier and cheaper to make and maintain a single point fuel injection system (be it via a pump or a carb) than it is to make individual injectors for each cylinder.

http://www.flightglobal.com/pdfarchi...0-%200562.html
http://www.flightglobal.com/pdfarchi...0-%200563.html
http://www.flightglobal.com/pdfarchi...0-%200569.html

If direct injection really was so great for piston aero-engines, the chances are that the Allies would have adopted it immediately post-war when all Axis technology was theirs for the taking. The fact that they didn't do so speaks volumes.

See also:
http://www.wwiiaircraftperformance.o...in-lovesey.pdf
(The chronology of engine ratings and outputs may also be of general interest; presumably Mr. Lovesey counts as a primary source...)

[CaptainDoggles]

If direct injection really was so great for piston aero-engines, the chances are that the Allies would have adopted it immediately post-war when all Axis technology was theirs for the taking. The fact that they didn't do so speaks volumes.

But engine design was heading towards turboprops in those years (and obviously turbojets), what with the "trent-meteor" hybrid that was instrumental in the development of Rolls-Royce's Dart engines.

[Crumpp]

2009 Technology of the Year: Direct Fuel Injection

Direct injection-squirting pressurized fuel straight into each cylinder-is the key to keeping internal-combustion engines relevant in the future. For enabling a major step forward in gas and diesel engine power, efficiency, and cleanliness, direct fuel injection is AUTOMOBILE MAGAZINE's 2009 Technology of the Year.

While injecting fuel into the combustion chamber requires approximately fifty times the pressure used with port injection and additional electronic control sophistication, significant benefits are delivered. Since no fuel is deposited on intake-port walls, the air/fuel mixture can be more precisely maintained, benefitting both mileage and emissions. In addition, the cooling effect of gasoline droplets changing to vapor inside the combustion chamber facilitates a higher compression ratio without incurring detonation. Squeezing the mixture harder during compression and allowing it to expand longer on the power stroke wrings additional power out of every ounce of gasoline.

http://www.automobilemag.com/feature...ion/index.html

Single point injection has no advantages over direct fuel injection at all. The Supercharger is on a completely separate circuit and the engine still receives all the benefits of supercharging with the additional benefits of direct injection.