Inaccurate performance data for BOB fighters in COD comparing to RL data

[lane]

Originally Posted by 41Sqn_Banks

Exactly. For example Operational Notes for Pilots on Merlin II and III. 2nd Edition January 1939. It doesn't mention +12 boost, it mentions that a unspecific higher boost than +6 1/4 can be used for take-off by operating the boost-control cut-out.
It doesn't mention any modification, only that 100 octane fuel must be used. (Note that the 4th Edition from April 1940 mentions that "sparking plugs approved to withstand this high boost must be used", so if there was any modification required in January 1939 it would have been mentioned.)
It does however state that this higher boost setting has to be determined on the ground before it is used by listening if there is detonation.

The 4th Edition from April 1940 now gives +12 boost and as already said mentions that specific sparking plugs must be used and that the boost-control cut-out has to be modified to limit boost to +12 boost.
Looks like in April the cylinder head modification was no longer required (maybe because all engines had been modified).

My copy confirms your statement:

Emergency +12 lbs./sq. in. Boost Operation: Pilot's Notes, Merlin II, III and IV, 4th Edition, April 1940, page 6.

[41Sqn_Banks]

Originally Posted by Crumpp

Let's see this unspecific boost!

As said, there is no fixed boost value specified. The possible boost value had to be determined individually before the take-off. I will dig out the pages ASAP.

The June 1940 Operating Instructions make no mention whatsoever for a higher boost at take off.

It does:

http://forum.1cpublishing.eu/attachm...1&d=1332111649
http://forum.1cpublishing.eu/attachm...3&d=1332111666

Well, as long as you are not doing a "long period take-off" ...

[335th_GRAthos]

I am sorry to jump into this discussion (I would prefer to burn in my burning Bf109 with a properly exploding central fuel tank than post in this thread, LOL) but I there is something that raised my curiocity:

I am looking at the numbers for the first year of war (Sep.'39 - Aug.'40)
Did anybody notice that the line Total for first year numbers make no sense?


Just wonder what the reason may be for this discrepancy.

~S~

[lane]

Originally Posted by 335th_GRAthos

I am looking at the numbers for the first year of war (Sep.'39 - Aug.'40)
Did anybody notice that the line Total for first year numbers make no sense?

Actually, the figures do add up and do make sense. The figures given are Monthly Average Consumption in thousands of tons.

For the 1st Year of War Sept.-Nov.'39, 16 is given as the monthly average, in thousands of tons, for that 3 months period.
With that understanding (16x3) + (14x3) + (23x3) + (10x3) + (26x3) = 267

[Al Schlageter]

Originally Posted by lane

Here's two more that come to mind:

245 Squadron, May 1940, Hurricane
264 Squadron, May 1940, Defiant

Thanks lane though I am really only interested in Spit and Hurrie squadrons.

Did 245 still use 100 fuel after it went to Aldergrove in July 1940?

[NZtyphoon]

Originally Posted by Crumpp

Let's see this unspecific boost!

The June 1940 Operating Instructions make no mention whatsoever for a higher boost at take off.




It is being read properly. That is backed up by the logs.

Notice the engine is modified during Service Inspection:





LMAO!! It specifics which method of compliance will be used in production. It does not say a single thing about engines produced in the past!!

If you can't read properly that's your problem; the form says absolutely nothing about what type of inspection K9878 is undergoing, and the final sentence says END change to 100 Octane, referring to the fact that the entire unit has gone over to 100 Octane by 16 March 1940, PRE dating AP1590B which is dated 20 March 1940 and confirming what AP1590 says, that Merlin engines were already being modified.

[Crumpp]

If you can't read properly that's your problem;

I can read very well. The entry complies with the technical instructions found in A.P. 1590B/J.2W. It does not mean they are using 100 Octane fuel.

Once again, where is in any significant quantity of the fuel at the airfields in March 1940? Answer is there is no fuel in any significant quantity. Your own documentation shows that. Problem is you gamers are so bent on finding what you need that you do not see any other outcome.

Once again, if 100 Octane fuel is not listed as the primary Operating Instructions even in June 1940.

For example Operational Notes for Pilots on Merlin II and III. 2nd Edition January 1939.

I have the June 1940 version. All previous instructions are included in the later version AND any technical orders are incorporated. That is a fact.

If the later version of the Operating Instructions does not include it, you can bet the earlier did not.

That looks like somebodies photo-shop work.

[Crumpp]

Yes, just as the Total for 1st Yr. = 267 refers to 100 Octane and Other Grades.

Baloney.

Total is just that...TOTAL for the year.

In 1938 they had 100 Octane in quantity?? No they did not.

I don't think it has anything to do with the columns above it. Can you prove it does not?

[Crumpp]

Well, as long as you are not doing a "long period take-off" ...

It is not at take off. The +12lbs is allowable up to 1st Gear FTH.

Even in June 1940, 100 Octane has not eclipsed 87 Octane as the predominate fuel. The Pilots Operating Instructions would have published with the latest data. This is reflected in Table II as no significant quantities of 100 Octane exist at the airfields.

If the technical instructions were published in March then that gives them 4 months until the update is published.

The Operating Notes still list 6 1/2lbs as the 5 minute all out emergency setting for the engine as the most common configuration.

The limiting operational conditions does not make any mention at all of 100 Octane.

Frankly, it is very difficult to follow this discussion ...

For me it is easier to understand articles that have reviewed the literature and where I can draw conclusions:


Palucka, Tim. The Wizard of Octane. American Heritage of Invention & Technology, 20. 3 (Winter 2005): 36-45.
Resume: IF, AS THE DUKE OF WELLINGTON IS SUPPOSED TO HAVE SAID, the Battle of Waterloo was won on the playing fields of Eton, then one can assert with equal justice that the Battle of Britain was won at the Stevens Hotel, in Chicago, on November 18, 1938. It was there, at the annual meeting of the American Petroleum Institute, that Arthur E. Pew, vice president and head of research of the Sun Oil Company, described his company's extraordinary new catalytic refining process. Using it, he said, Sun was turning what was normally considered a waste product into gasoline-and not just ordinary gasoline, but a highoctane product that could fuel the era's most advanced airplanes. That process would make a crucial difference in mid-1940, when the Royal Air Force started filling its Spitfires and Hurricanes with 100-octane gasoline imported from the United States instead of the 87 octane it had formerly used. Luftwaffe pilots couldn't believe they were facing the same planes they had fought successfully over France a few months before. The planes were the same, but the fuel wasn't. In his 1943 book The Amazing Petroleum Industry, V. A. Kalichevsky of the Socony-Vacuum Oil Company explained what high-octane gasoline meant to Britain: "It is an established fact that a difference of only 13 points in octane number made possible the defeat of the Luftwaffe by the R.A.F. in the fall of 1940. This difference, slight as it seems, is sufficient to give a plane the vital `edge' in altitude, rate of climb and maneuverability that spells the difference between defeat and victory."

Bailey, Gavin. The Narrow Margin of Criticality: The Question of the Supply of 100-Octane Fuel in the Battle of Britain. English Historical Review; Apr2008, Vol. 123 Issue 501, p395-411, 17p, 3 Charts
Resume: The article focuses on the supply of 100-octane fuel during the battle of Great Britain. Aviation historians have advanced the supply of 100-octane aviation fuel as critical American contribution to the battle. A study of the contemporary Air Ministry records in the Public Record Office shows that this assertion can be challenged. The challenge can be made on the grounds of the aircraft performance benefit involved, as showed by contemporary Royal Air Force (RAF) testing, and on the national origin attributed to 100-octane fuel supplies. The records reveal that contrary to the assertion of aviation history, the supply of 100-octane fuel to RAF in time for use in the battle must be attributed to pre-war British planning and investment on the rearmament period of the late nineteen-thirties.

My only conclusion is that only in this forum I read the statement that 100-octane did not have a role in the Battle of Britain (statement supported by the devs? ) ... and not supported in a peer-reviewed article...

The answer to the question of the extent of 100 Octane all depends on when you place the dates of the Battle of Britain. September 15th 1940 as an end date is a post war and has nothing to do with Fighter Command's actions in context.

The RAF official history takes the battle out to the end of October 1940 when German Daylight raids ceased. Other histories end the battle in December 1940:

On 9th September 1940, No 92 Squadron, with Geoffrey Wellum now operational, was moved back to 11 Group, to Biggin Hill, one of the most famous Fighter Stations, and to the Sector that experienced the most ferocious fighting during the Battle of Britain. Although they were entering the fray towards the end of the Battle, by December 1940, No 92 Squadron would claim 127 enemy aircraft destroyed.

http://www.raf.mod.uk/bbmf/theaircra...eoffwellum.cfm

The German's end the battle in May 1941 when their bombers where transferred to the east and offensive operations against England were called off.

[Crumpp]

Pilots Operating Limitations, June 1940:



All out 5 minute Emergency rating as listed in June 1940:



If by June 1940, 30 squadrons were operating 100 Octane, then almost the entire force would need the +12lbs boost instructions instead of the 87 Octane. The Operating Notes would have reflected this and the 100 Octane limits would have been included.

That is a fact and how it works.