Performance Characteristics

1.   The introduction of a higher quality aviation fuel has now been under consideration since the later part of 1942. It was not, however, until July 1943 that final agreement was achieved as to the precise performance characteristics which would be acceptable to engine manufactures and would be attainable by the use of available materials. It was then decided that 150 Grade fuel should have,

(a)      A weak mixture rating of 100 Octane, i.e. the same as for present 130 Grade.

(b)      A 20% increase of effective anti knock value at rich mixture strength on 130 Grade.

Effect on Service Types

2.   As 150 Grade will give no improvement in performance at cruising or weak mixture conditions, it will, generally speaking, not be of advantage to Bombers. The 20% increased power output which it will allow in engines such as the Merlin 66 when operating at rich mixture strength for all out level flight or climb, is estimated to give the Spitfire, for instance, an increased speed of 29mph and an increase of 1000 ft/min in rate of climb up to rated operational ceiling. It therefore may be classified as essentially a Fighter fuel.

3.   As to its usage in certain American fighter types, it is probable that current flight tests will demonstrate its advantages.

Methods of Manufacture

4.   With fuel characteristics settled, it was necessary to reconcile the 15-20% loss of potential 130 Grade Aviation fuel output which appeared inevitable if 150 Grade were manufactured. Suffice to say that after a great deal of laboratory and engine research, methods have now bean devised, insofar as U.K refineries are concerned, of eliminating the above potential loss of output. The most important factors in attaining this end are the clearance of 7.2 cc’s of T.E.L per imperial gallon in 150 grade fuel, and the use of components such as Mono Methyl Aniline, Xylidine and Butyl Benzene.

Status of British and American Discussion on 150 Grade.

5.   Whilst the Americans have been kept informed of the general trend of our research, and the U.S.A.A.F in the U.K have in fact been conducting flight tests, there has been no formal discussion with the Americans regarding the introduction of 150 Grade. It is, however, generally agreed that the present is not only an appropriate moment but that it is now essential to bring our proposals to their attention officially. This will be affected through Air Staff so that the whole requirement may be tabled in Washington by the Services at the highest possible level on the basis of its operational advantages. This view was shared by Colonel B. Johnson, U.S.A.A.F , who has been in close touch with the position in the United Kingdom and has been associated with the U.S.A.A.F’s fight tests.


6.   The latest fwd estimate of 150 Grade production from the United Kingdom refineries (on the assumption that we obtain certain components urgently from America) is:

February16,000 tons
March32,000 tons
April44,000 tons
May44,000 tons
June43,000 tons
Total ex U.K refineries
179,000 tons

7.   The above production can be achieved without any outside assistance except importation of 1,100 tons of Cumene Substitute from the U.S.A and 4,800 tons of Avaro from the Caribbean.

8.   In considering these figures some allowance must be made for the time lag between production at the refinery and availability at point of consumption. This has been achieved by presuming that entire months production is not available until the last day of the month in which it occurs; whilst the entire months consumption is assumed to occur on the first day of the month in question.

Estimated Requirements

9.   As available production of 150 Grade will not be sufficient to meet all the consumption of the A.E.A.F, the following figures are based on the estimated consumption of single engine fighter types. Again, as a phased estimate of consumption is not available, the estimated consumption requirements of the single engine fighter force, which will be available to the A.E.A.F at D +90 has been used. It is suggested that this quantity will be more than adequate to cover both the higher loss rate and scale of effort, which may be expected in the earlier phases of “OVERLORD” when the force will be much smaller. In view of the forgoing it is considered essential that the calculations should be examined by A.E.A.F in the light of phased estimated consumption.

10.   The following monthly consumption figures have been used.

S.E. Fighters A.E.A.F

R.A.F  8,500 tons per month.
U.S.A.A.F.28,000 tons per month.
Total36,500 tons
1 months reserve36,500 tons

Total Initial Requirements - 73,000 tons

11.   In the attached tabulations, it is assumed that 150 Grade cannot be introduced on the Continent for the A.E.A.F. until 73,000 tons is available, and thereafter A.E.A.F. consumption is estimated to be 37,000 tons per month.

Conclusions which can be deduced from the attached Tabulations

12.   The attached Tabulations comprise:

Table I   Forward production of 150 Grade Aviation Fuel phased back as described in paragraph 8 above.

Table II   Which sets out to show what quantities of 150 Grade would be available for Home Based Fighters, if first priority were given to the provision of the requirements of the A.E.A.F.

Table IIIA & IIIB   Respectively demonstrate the effect on the date when 150 Grade can be made available for the A.E.A.F. which would be occasioned respectively by setting aside 40,000 tons and 60,000 tons of 150 Grade for Home Based Fighters.

(a)   Table II


13.   This tabulation analyses the supply position if it were decreed that the allocation of 150 Grade to the A.E.A.F were to take absolute priority.


14.   It will be seen that the earliest the initial requirement of 73,000 tons of 150 Grade could be made available would be May. If operations occur in that month, there would also be available for Home Based Fighters, 19,000 tons in May, 7000 tons in June and 6,000 tons in July.

15.   On the assumption that operations commence in June, in addition to the full requirement for A.E.A.F single engine fighters, 63,000 tons would be available for Home Based Fighters in June and July.

(b)   Table IIIA  


16.   This tabulation examines the position if it were decided that 40,000 tons was to be made available for Home Based Fighters as a first priority.


17.   The earliest this quantity of fuel could be made available would be April, but the effect of allocating 40,00 tons to Home Based Fighters would be to postpone the date when 150 Grade could be introduced on the Continent until June. At that date, the A.E.A.F. initial requirement of 73,000 tons would be met with the margin of 23,000 tons available for other purposes. In July production would be sufficient to meet A.E.A.F. monthly consumption of 37,000 tons with a balance of 6,000 tons for others purposes.

18.   Should the operation start in May 40,000 tons could be available for Home Based Fighters, leaving a margin of 52,000 tons, which, however, would be inadequate to cover the initial requirement of the A.E.A.F. Consequently, the A.E.A.F. would still have to wait until June, for 150 Grade. Surpluses available for others purposes in June and July would be the same as in the preceding paragraph.

19.   If the operation were to commence in June, there would be sufficient 150 Grade fuel available to provide 40,000 tons for Home Based Fighters, and to meet the 73,000 tons initial requirements for A.E.A.F. single engine fighters, and still leave a margin of 23,000 tons. In July, there would be a further margin of 6,000 tons available for other purposes.

(c)   Table IIIB  


20.   This tabulation examines the position if it were decided that 60,000 tons was to be made available to Home Based Fighters as a first priority.


21.   It will be seen from the attached tabulation that the earliest that 60,000 tons could be made available for Home Based Fighters is May. At that date, in addition to meeting this requirement, there would be a balance of 32,000 tons which, however is insufficient to permit the introduction of 150 Grade A.E.A.F. Fighters in May. They would have to wait until June.

22.   On the basis of the operation commencing in June, there would be sufficient 150 Grade available to provide 60,000 tons of 150 Grade for Home Based Fighters, provide the 73,000 tons initial requirement of A.E.A.F. Fighters, plus a small margin of 3,000 tons. In each of the above cases, in the following month of July, there would be 6,000 tons available for other purposes over and above the 37,000 tons consumption requirements of A.E.A.F. Fighters.

Summary of Conclusions

23.(a).   On the basis of the figures used, it is apparent that the earliest a substantial quantity of fuel can be allocated, i.e. 40,000 or 60,000 tons for Home Based Fighters is May/June. This would still permit the allocation of one month’s consumption and one month’s reserves, i.e. 73,000 tons to A.E.A.F. Fighters in June.

24.(b).   The whole problem will be fundamentally influenced by the time phasing of the consumption build up. The figures used in the forgoing appear likely to be very much on the high side. It is, therefore, essential that A.E.A.F. should rework the figures on the basis of the latest agreed operational plan.

When this is done it will probably show that the initial requirement for the A.E.A.F. i.e. one months consumption plus 23 days reserve, will be substantially less than the 73,000 tons used in the above figures. This would have the immediate effect of making the packing problems involved more practicable with existing facilities, and advancing the permissible “zero” hour.

A further consideration is the later introduction of bulk on the Continent. The 37,000 tons used in the above figures for the single engine fighter consumption represents 67% of the total A.E.A.F. Aviation Fuel consumption. It would, therefore, seem reasonable to move 150 Grade in bulk, meeting forward packed requirements by refilling returned containers as far forward on the L. of C. as practicable, if, as it seems likely, it is impracticable to distribute two grades of aviation fuel in bulk.

The forgoing proposals are, at this stage, inevitably based on a certain element of surmise but it is felt they should be seriously considered when final appreciation is made, substituting the latest phased consumption estimates.

25.(c).   The fundamental purpose of the above appreciation is not to arrive at conclusions, but present the problem in an orderly manner so that Air Staff and the relevant Administrative Branches may evolve their final plans.

E.49.(Sgd.) D.I. FARQUARSON.
25th January 1944. S/Ldr