Thanks FLYBOYJ, parsifal and krabat!
Hi Juha:
I agree that there are sufficient primary sources and credible literature citations available in the various threads on this board and elsewhere such that there is really little mystery left regarding the conversion of Fighter Command to 100 octane fuel. I can't see the point of putting much more research time in to the subject as I wouldn't expect to increase my understanding of events to any significant degree.
Perhaps the following will further flesh out the story.
Air Ministry document AP1590B/J.2-W dated 20.3.40 clearing +12 boost states:
1. The emergency use of higher boost pressures up to +12 lb/sq.in. is now permitted for short periods by operation of the modified boost control cut-out.
The Spitfire I Pilot's Notes states:
"When using 100 octane fuel, +12 lb./sq.in. boost, obtained by operating the boost control cut-out, may be used for short periods."
Air Chief Marshall Dowding's memo dated 1 August 1940 states:
"The use of the automatic boost cut out control enables the pilot to get an emergency boost of + 12 lbs. per sq.in. from the engine for 5 minutes when circumstances demand it. Some pilots "pull the plug" with little excuse on every occasion."
Understanding that 100 octane fuel is required to safely operate the boost cutout, pull the plug/tit or obtain +12 lbs emergency boost on Merlin II and III engines equipping Spitfire Mk I and Hurricane Mk I, we can see that following pilots comments demonstrate use of 100 octane fuel. These are obviously highly condensed; please see the links or citations for the full accounts.
Pilot accounts from Hurricane Squadrons:
56 Squadron Combat Report noting +12 boost for Hurricanes, 9 May 1940:
S/L J.O.W. Oliver, 85 Squadron, 10 May 1940: "... I pulled the plug."
F/O Paul Richey, 1 Squadron, 11 May 1940: "...boost-override pulled."
F/O E. J. Kain, 73 Squadron, 14 May 1940: "...pulling his boost cut out..."
P/O D. W. A. Stones, 79 Squadron, 14 May 1940: " I now pulled out the emergency boost-plug for the first time ever..."
P/O R. P. Beamont, 87 Squadron, 15 May 1940: "I pulled the tit'* for over-boost... *Emergency boost over-ride on the Merlin engine."
S/L E. M. Donaldon, 151 Sqdn., Combat Report, 18 May 1940: "I pulled the plug and climbed at 10 lbs boost…"
P/O John Bushell, 151 Sqdn., Combat Report, 18 May 1940: "I used full 12 lb boost (pulled the plug) and overtook EA rapidly."
P/O F. B. Sutton, 56 Squadron, 18 May 1940: Vitry, France: "...I had to pull the tit... Emergency boost control giving extra power"
F/O C. F. G. Adye, 17 Squadron, 18 May 1940: "...pulled emergency boost control..."
F/Lt I. R. Gleed, 87 Squadron, 18 May 1940: "At about 100 feet I straighten up, pull the tit *; a jerk as my supercharger goes up to twelve boosts."
F/Lt I. R. Gleed, 87 Squadron, 19 May 1940: "Here goes with the tit. A jerk - the boost's shot up to twelve pounds; speed's increased by 30 m.p.h."
F/O C. F. G. Adye, 17 Squadron, 19 May 1940: "...pulled emergency boost..."
Sgt. L.H.B. Pearce, 79 Squadron, 20 May 1940: "Pulled tit..."
Sgt. J. C. Harrison, 229 Squadron, 28 May 1940: "I pulled the emergency boost and followed him down still firing."
P/O C. M. Simpson, 229 Squadron, 29 May 1940: "...I followed it down with boost out and pulled."
Sgt. P. Ottewill, 43 Squadron, 1 June 1940: "...automatic boost cut-out pulled."
F/Lt. R. G. Dutton, 145 Squadron, 1 July 1940:...pulled the plug..."
P/O G. E. Goodman, 1 Squadron, 18 August 1940: "...I pulled the plug..."
P/O Wicks, 56 Squadron, 30 August 1940: "With full throttle emergency boost..."
P/O J. R. B. Meaker, 249 Squadron, 6 September 1940: "...so I pull the plug..."
F/Lt J. A. Kent, 303 Squadron, 9 September 1940: "...I pulled the boost override plug..."
P/O T. F. Neil, 249 Squadron, 18 September 1940: "Plug pulled..."
P/O R. G. A. Barclay, 249 Squadron, 27 September 1940: "I had to use automatic boost cutout to catch up the 109."
S/L A. A. McKellar, 605 Squadron, 7 October 1940: "I followed one, pulled my boost control, and speedily made up on him."
Pilot comments from Spitfire Squadrons:
F/O D. H. Watkins, 611 Sqdn, 2 June 1940: "…emergency boost"
P/O John Freeborn , 74 Sqdn, 24 May 40: "boost cut out"
P/O Colin Gray, 54 Sqdn, 25 May 40: "…emergency boost tit"
P/O Al Deere, 54 Sqdn, 26 May 40: "12 boost"
F/Lt Lane, 19 Sqdn, 26 May 40: "12 lb. boost"
P/O M. P. Brown, 611 Sqdn, 2 June 40: "boost cut out"
F/Lt John Webster, 41 Sqdn, 19 June 40: "12 lbs boost"
F/Lt D. P. Kelly, 74 Sqdn, 28 July 40: "boost cutout"
F/Lt John Webster, 41 Sqdn, 28 July 40: 12 boost"
F/Lt John Webster, 41 Sqdn, 29 July 40: "twelve boost"
P/O George Bennions, 41 Sqdn, 28 July 40: emergency boost"
P/O Art Donahue, 64 Sqdn, 5 August 1940: "…emergency throttle"
F/Lt John Webster, 41 Sqdn, 8 August 40: "12 boost"
F/O R. W. Wallens, 41 Sqdn, 11 August 40: "12 lbs boost"
F/Lt George Gribble, 54 Sqdn, 15 August 40: "12 boost"
F/O Hugh Dundas, 616 Sqdn, 15 August 40: "through the gate"
F/Lt Robert F. Boyd, 602 Sqdn, 18 August 40: "10 lbs boost"
P/O James Morton, 603 Sqdn, 28 August 40: "pressed the tit"
P/O Ronald Berry, 603 Sqdn, 31 August 40: "emergency boost"
Sgt Jack Stokoe, 603 Sqdn, 1 September 40: "boost override"
P/O Roger Hall, 152 Sqdn, 4 September 40: "energy boost"
F/O Robert Oxspring, 66 Sqdn, 6 September 40: "through the gate for emergency power"
P/O R. D. Elliot, 72 Sqdn, 9 September 40: "MAX Boost (12 lbs)"
F/O Brian Macnamara, 603 Sqdn, 27 September 40: "full throttle and with the red lever pressed"
P/O Bob Doe, 234 Sqdn: "pull the plug"
Geoffrey Wellum, 92 Sqdn" "emergency boost override"
P/O David Crook, 609 Sqdn, 30 September 40: "'pulled the plug', i.e. pushed the small handle on the throttle quadrant that cuts out the automatic boost control thus allowing one to use emergency power."
F/O D. McMullen, 222 Sqdn, 15 October 40: "12 boost"
The squadrons noted above are as follows: Spitfire – 19, 41, 54, 64, 66, 72, 74, 92, 152, 222, 234, 602, 603, 609, 611 616. 610 squadron Spitfires are shown being refueled with 100 octane above. Hurricane – 1, 17, 43, 56, 73, 79, 85, 87, 145, 151, 229, 249, 303 605. I'm quite sure more accounts and documentation will be found demonstrating 100 octane use by other squadrons during the Battle of France, during the Dunkirk evacuation and during the Battle of Britain.