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Author Topic: The Spitfire and its petrol  (Read 6024 times)
NZTyphoon
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« on: June 30, 2009, 12:49:44 AM »

This came up recently Spitfire Fuel Apparently the Royal Society of Chemists have released a paper exploring the use of 100 Octane fuel by RAF fighters during the Battle of Britain; according to this the scientist who invented a new process for manufacturing this fuel in the USA was an ex-pat Frenchman Eugene Houdray .

My feeling is that there were plenty of people involved in the development and manufacturing of this new aviation fuel in the mid to late thirties. Edgar Brooks, for example, describes Air Commodore Banks and Dr Sweeny as having important roles to play; another who is cited as pushing for the importation of 100 octane fuel for the RAF was Roy Fedden, who designed most of the successful Bristol engines. I also  think it is a little simplistic to say that the use of the fuel was absolutely decisive during the Battle of Britain. Still, I would be interested in reading the published paper.
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« Reply #1 on: July 02, 2009, 01:13:19 PM »

Quoted from can't-remember-where Smiley

"The first bulk shipment of 100-octane fuel had arrived in Britain in June 1939 from the Esso refinery in Aruba. This and subsequent tanker shipments from Aruba, Curacao and the USA were stockpiled while the RAF continued to operate on 87 octane petrol. Having secured sufficient quantities of 100 octane, Fighter Command began converting its engines to this standard in March 1940, allowing boost (manifold) pressures to be raised without the risk of detonation in the cylinders. This initial increase in maximum boost from 6 lb to 9 lb delivered a useful power growth of around 130hp at the rated altitude. Subsequent increases in permitted boost pressures throughout the war saw the Merlin's maximum boost on 100-octane fuel rise to 18 lb, allowing considerable increases in power output. The introduction of 150-octane fuel in 1944 allowed further increases to 25 lb boost."

This is about fuel shipments, but I'm positive that trials with 100-octane gasoline must have commenced well before that. How abut the Schneider racers, what kind of fuel was used fore these? Anyone?

/M.

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gingerbob
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« Reply #2 on: July 02, 2009, 05:00:22 PM »


This is about fuel shipments, but I'm positive that trials with 100-octane gasoline must have commenced well before that. How abut the Schneider racers, what kind of fuel was used fore these? Anyone?


I'd have to do some digging to say anything about the 'pre-history' of 100 Octane, but the Schneider racers were using a custom cocktail- not at all a production or long-term use fuel.  As I recall Rod Banks goes into it in some detail in his book "I Kept No Diary".
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NZTyphoon
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« Reply #3 on: July 04, 2009, 01:21:42 PM »

According to Gruenhagen: Mustang; the story of the P-51 fighter the fuel used was made up of 60% methanol, 10% acetone and 30% benzol, which was devised by F R Banks. The R engine was able to generate 2,530 hp at 3,200 rpm using 60 inches of hg. (p. 70)
Just for interest, according to Warner - complete history of Bristol Blenheim the Bomber Command Blenheim IV units were converting their aircraft to use 100 Octane fuel in early September 1939, completing the job by 7 October. Using this fuel their top speed increased from 225 mph to 248 mph at sea level! (2nd revised edition pp. 135, 314) - not that it helped the poor crews much. Sad
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« Reply #4 on: July 04, 2009, 01:44:48 PM »

Jeffrey Quill mentions in his book that the fuel used for the "Schneiderised" Speed Spitfire was:

20% Californian or Romanian gasoline (anyone's guess why just one of these - possibility to push the octane number, perhaps?)
60% benzole
20% methanol
+ tetraethyl lead 4cc/gallon
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« Reply #5 on: July 04, 2009, 01:50:41 PM »

According to Gruenhagen: Mustang; the story of the P-51 fighter the fuel used was made up of 60% methanol, 10% acetone and 30% benzol, which was devised by F R Banks. The R engine was able to generate 2,530 hp at 3,200 rpm using 60 inches of hg. (p. 70)
Just for interest, according to Warner - complete history of Bristol Blenheim the Bomber Command Blenheim IV units were converting their aircraft to use 100 Octane fuel in early September 1939, completing the job by 7 October. Using this fuel their top speed increased from 225 mph to 248 mph at sea level! (2nd revised edition pp. 135, 314) - not that it helped the poor crews much. Sad

Because the worldwide production of 100-octane fuel was still rather limited before the war, and its supply was all relying on imports, the decision to convert the entire RAF to new fuel must have been a bold one, involving a mass of logistical problems to be resolved - although I never managed to find a thorough account of this change anywhere. I imagine that resolving storage and supply logistics was probably a more complex issue than converting the engines. Still an impressive feat.
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NZTyphoon
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« Reply #6 on: July 05, 2009, 03:08:59 AM »

Because the worldwide production of 100-octane fuel was still rather limited before the war, and its supply was all relying on imports, the decision to convert the entire RAF to new fuel must have been a bold one, involving a mass of logistical problems to be resolved - although I never managed to find a thorough account of this change anywhere. I imagine that resolving storage and supply logistics was probably a more complex issue than converting the engines. Still an impressive feat.

Yes indeed it was an impressive feat; sorting out what happened in 1940 alone requires a lot of work chasing down all sorts of information. Others have researched this in great detail discussion on 100 Octane use in 1940.

I've been working out how much shipping was involved in importing aviation fuel fuel in 1940, with interesting results. Morgan and Shacklady, for example, say that lots of tankers were destroyed by U-Boats (pp. 56) However, my preliminary work shows that only one tanker carrying "avgas" was destroyed by a mine laid by a U-Boat - this was out of 44 avgas carrying ships in the HFX and HX (and associated BHX)  convoys which reached Britain between January and late October 1940. I won't bore you with the details.  Wink
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Edgar Brooks
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« Reply #7 on: July 05, 2009, 11:27:32 PM »

I suspect that the French input was in making production faster, not in the initial experiments.  Rod Banks asked for engines capable of using 100 octane in 1937, over a year before this Frenchman "invented" it.  The professor gives credit to Sun Oil, but deliveries came from Standard Oil (now Esso,) in Jamaica, and were mixed to the British requirement for good "rich mixture response."
It's also far too simplistic to claim that the fuel was the sole reason for the increase in performance.  Being charitable, we'll assume that the professor doesn't know about the de Havilland engineers, who raced all over the countryside, fitting constant-speed props, in place of the two-pitch.  This dramatically improved the Spitfire's "liveliness," with the take-off run cut from 420yds to 225, and the time-to-climb showed a similar result.  2,000' in 42 seconds, against 77 seconds, 5,000' 108 v 180, 10,000' 210 v 330, 15,000 318 v 486.
Banks recommends that anyone wanting to do further research should consult "Milestones in Aviation Fuels," by W.G.Dukek, D.P.Winans & A.R.Ogsten, a paper given at A.I.A.A. Designers and Operators meeting, in July 1969, in L.A.
Edgar
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