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

[Kurfürst]

Moreover:

16 Fighter and 2 Bomber Squadrons by September 1940

"The change-over would start towards the end of the present year and ACAS would select the particular squadrons which would operate on the new fuel."

[NZtyphoon]

Originally Posted by Kurfürst

All the specifics they managed to dig up that the RAF decided in March 1939 to equip 16 Fighter Squadrons for 100 octane by September 1940, and that the 'certain' Squadrons 'concerned' were equipped so by mid-May 1940. Oh wait - we knew that already from books, just see the Spitfire the History scan...

Originally Posted by Kurfürst

And all the facts from the National Archives say

- that the RAF decided in March 1939 to equip 16 fighter + 2 bomber Squadrons with 100 octane

- that in May 1940 they acknowledged that the fuel was delivered to select fighter and bomber squadrons

- 100 octane vs 87 octane issues figures for 1940 all show that 87 octane was the primary fuel issued during the Battle, and 100 octane issues did not increase or took prominence until the day battle was pretty much over.

Originally Posted by Kurfürst

Moreover:

16 Fighter and 2 Bomber Squadrons by September 1940

"The change-over would start towards the end of the present year and ACAS would select the particular squadrons which would operate on the new fuel."

What hasn't been mentioned is that this was provisional: para 8 says:

"A.M.D.P asked that D.D.C(3) should keep him informed of the rate of output of 100 octane fuel in order that the rate of change-over of squadrons to this fuel could be kept under review in the light of any diminution or acceleration in supplies." (attachment 1)

The 16 fighter and 2 bomber squadrons by September 1940 was hypothetical, based on March 1939 conditions of fuel supply, and was flexible, not fixed in stone.

Supplies of 100 octane fuel continued to increase from 202,000 tons in December 1939, which was the time specified for the change over.

In November 1940 it was considered that there were "adequate reserves" of 100 octane fuel to go ahead with the modification of all Hurricane and Spitfire Merlin engines to use 12 lb boost.



Problem: squadrons did not, and could not hold their own fuel supplies, to require them to do so would be an operational and logistical nightmare: it was airbases that were supplied with fuel, not individual squadrons. In the 6 May 1940 paper (Item 9 7th Meeting Summary...) "Units concerned" cannot be talking about individual squadrons, it is referring to bases which, depending on their importance, (eg; Sector Station) hosted up to three squadrons. 18 squadrons = 8-10 airbases.

The December 7 1939 letter, which sets out a process for supplying 100 Octane fuel starts:

"I have the honour to refer to my letter...dated 27 October 1939, regarding the issue of 100 Octane Fuel for use in Hurricane and Spitfire aircraft in this Command." (attachment 2)

25 Fighter Stations were listed as requiring 100 octane fuel "in the first instance", including non-operational Kenley, Usworth and Hendon, with a further 17 non-operational bases which required supplies for visiting aircraft, but "which have no Hurricane or Spitfire aircraft at the moment."

Squadrons that were to use 100 octane fuel were not selected by Squadron number but by the type of aircraft used. Bases that hosted these aircraft types were accordingly supplied with 100 octane fuel. Same for the Bomber squadrons, namely Blenheims. The only Blenheim capable of using 100 octane fuel was the Mk IV the first of which emerged in March 1939. The Defiant was not listed in December because it was not yet operational.

All of the 11 Group Sector stations were listed, plus Filton which, in June 1940, became part of the new 10 Group; 4 out of 5 12 Group sector stations, 2 out of 5 13 Group sector stations, and 11 other airfields, including 6 of 11 Group were listed.

In May 1940 stocks of 100 Octane fuel were 294,000 tons, while stocks of "other grades" were 298,000 tons (attachment 3).

Far from there being a crisis in the supply, of 100 Octane preventing a continued change over of units (according to the famous Pips document) for the next two months, 100 Octane fuel was becoming the dominant fuel type being stocked; by August 404,000 tons was being held, cf 230,000 tons of other grades.