100-octane fuel in the RAF in 1940

[pbehn]

Calum, it's clear you don't want to share any information. But why don't you go parasite another thread?

I could play the contempt game too, hitting masters-degree-of-not-disclosed-university-which-happens-to-be-deep-in-the-UK-ranking-and-let's-talk-about-global-rankings and never-been-employed-in-a-large-company-because-lacking-basic-social-skills. But would that help me understand anything about 100-octane?

Mr Douglas spends a considerable amount of his time and money on research for books, one of which I have bought.

 

[pbehn]

If such is the case, let me correct the wording. "Not abiding by the commonly accepted rules of research in hard or social sciences" may be more accurate, doesn't it?

Please learn the first rule of holes. When you find yourself in a hole, stop digging. In the fields he is expert in Mr Douglas is without doubt the most informed researcher here and his contributions reflect that. However his living is made from his expertise and research, he has no obligation to anyone to hand it all over on a message board forum, just because you want to save a lot of time and money. You just invented your "rules" because you want free stuff, so be careful with the word "parasite".

 

[Mori]

Please learn the first rule of holes. When you find yourself in a hole, stop digging. In the fields he is expert in Mr Douglas is without doubt the most informed researcher here and his contributions reflect that. However his living is made from his expertise and research, he has no obligation to anyone to hand it all over on a message board forum, just because you want to save a lot of time and money.

Thanks for the rule of holes, I will abide to it.

I can't imagine Mr Douglas to have any "obligation", I merely pointed that a document whose exact source is withheld usually signals a problem, and that not citing sources is not the standard way research works. Please confirm that saying so is not trespassing rules of the forum (if so, won't do it again).

Discussing with experts on this board is certainly a way to "save a lot of time". It's the whole purpose of discussing with experts, actually: being more relevant, saving time. Is that wrong...?

 

[Engineman]

Thanks for the rule of holes, I will abide to it.

I can't imagine Mr Douglas to have any "obligation", I merely pointed that a document whose exact source is withheld usually signals a problem, and that not citing sources is not the standard way research works. Please confirm that saying so is not trespassing rules of the forum (if so, won't do it again).

Discussing with experts on this board is certainly a way to "save a lot of time". It's the whole purpose of discussing with experts, actually: being more relevant, saving time. Is that wrong...?

Keep digging.

Eng

 

[pbehn]

Thanks for the rule of holes, I will abide to it.

I can't imagine Mr Douglas to have any "obligation", I merely pointed that a document whose exact source is withheld usually signals a problem, and that not citing sources is not the standard way research works. Please confirm that saying so is not trespassing rules of the forum (if so, won't do it again).

Discussing with experts on this board is certainly a way to "save a lot of time". It's the whole purpose of discussing with experts, actually: being more relevant, saving time. Is that wrong...?

The exact source of the document is Bentley Priory, stated at the top.

 

[Deleted member 68059]

"I could play the contempt game too, hitting masters-degree-of-not-disclosed-university-which-happens-to-be-deep-in-the-UK-ranking-and-let's-talk-about-global-rankings and never-been-employed-in-a-large-company-because-lacking-basic-social-skills. "

You may find a rough outline of my international standing in engineering, aviation and consulting on my website, which includes being a registered (and active) Air Accident Consultant with the CAA

PS> Is this you back again under a new name, AGAIN, Xylstra, or are there really two separate people alive this full of angry nonsense-waffle ?

 

[Mike Williams]

RAF use of 100 octane during the Battle of Britain is well sorted. Less well widely known and understood is RAF use of 100 octane during the Battle of France. Published accounts during the war show the use of 100 octane and its benefits prior to and during the battle of France. Maybe this was forgotten in subsequent generations or the writings about the BoB just eclipsed those of the Battle of France?

Flight 28 March 1940

W/C Ian Gleed D.F.C., Arise to Conquer, (Random House, New York 1942) p. 49. F/Lt I. R. Gleed, 87 Squadron, 18 May 1940

Barry Sutton, The Way of a Pilot, (MacMillan & Co, Ltd., London 1943) pp. 79-80. P/O F. B. Sutton, 56 Squadron, 18 May 1940 Vitry, France:

Paul Richey DFC, Fighter Pilot (Redwood Press, Wiltshire 1990) p 76. (first published in Great Britain by B.T. Batsford Ltd., 1941.)F/O Paul Richey, 1 Squadron, 11 May 1940 "...boost-override pulled."
http://www.wwiiaircraftperformance.org/hurricane/richey-pg76.jpg

Hurricanes and Blenheims in France were using 100 octane in the spring of 1940 when the battle intensified:
Scale of Reserve Stocks of Aviation Fuels to be held in France for the A.A.S.F., 7 May 1940
Petrol and Oil requirements for R.A.F. Component on 15th May 1940.

Hurricane squadrons participating in the Battle of France: AASF Hurricane squadrons - 1, 73 & 501. RAF Air Component 3, 79, 85, 87, 504, 607, 615. 11 Group Hurricane Reinforcements 17, 32, 56, 111, 145, 151, 213, 229, 242, 245, 253, 601

Combat Reports and pilot accounts note +12 boost or use of boost control cut-out, only available when using 100 octane fuel:

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." Paul Richey DFC, Fighter Pilot (Redwood Press, Wiltshire 1990) p 76. (first published in Great Britain by B.T. Batsford Ltd., 1941.)
F/O E. J. Kain, 73 Squadron, 14 May 1940 "...pulling his boost cut out..." Noel Monks, Fighter Squadrons, (Angus and Robertson, Sydney : London, 1941), p 98-99 (See also Cull, Twelve Days in May), pg 124.
P/O D. W. A. Stones, 79 Squadron, 14 May 1940 " I now pulled out the emergency boost-plug for the first time ever..." Donald Stone, Dimsie, (Wingham Press, Canterbury, 1991), p 32.
Sgt. R. C. Wilkinson, 3 Squadron, 14 May 1940 "12 P.S.I." Kenneth James Nelson, C.D., Spitfire RCD, The Wartime Exploits of Royce Clifford Wilkinson O.B.E, D.F.M. & Bar, Hignall Printing Ltd., Canada, 1994). p. 6.
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." Roland Beamont, My Part of the Sky, (Patrick Stephens Limited, Wellingborough, Northamptonshire), pg 30.
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" Barry Sutton, The Way of a Pilot, (MacMillan & Co, Ltd., London 1943) pp. 79-80
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." W/C Ian Gleed D.F.C., Arise to Conquer, (Random House, New York 1942) p. 49.
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. "Ibid p. 61.
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 K. B. McGlashan, 245 Squadron, 28 May 1940 "We'd boost an extra four pounds, from eight to twelve" S/L Kenneth Butterworth McGlashan with Owen Zupp, Down to Earth, (Grubb Street, London, 2007), pg 29.
P/O C. M. Simpson, 229 Squadron, 29 May 1940 "...I followed it down with boost out and pulled."

Then there are the Spitfires that helped over Dunkirk, for example:

For more of that see also Spitfire Mk I Testing

 

[Mori]

PS> Is this you back again under a new name, AGAIN, Xylstra, or are there really two separate people alive this full of angry nonsense-waffle ?

You confuse me for someone else. This may explain why your behavior is so defensive. The site administror(s) know from my IP I don't have another account. Besides, I'm sure I make EFL grammar mistakes that others don't. You are not such a Sherlock Holmes after all. But it seems you routinely trigger fights with fellow members of this site...

It would have been so easy to just say "this doc is from AIR 2/1234". You would have been the nice, open-minded, confident gentleman. And what could I reply?

 

[Mori]

RAF use of 100 octane during the Battle of Britain is well sorted. Less well widely known and understood is RAF use of 100 octane during the Battle of France. Published accounts during the war show the use of 100 octane and its benefits prior to and during the battle of France. Maybe this was forgotten in subsequent generations or the writings about the BoB just eclipsed those of the Battle of France?

Thanks for putting together this long post. The mass of data as well as its diversity leaves no doubt about 100-octane fueling the RAF during the battle of France.

Since the article from G.Bailey concludes that 100-octane had a marginal (and perhaps insignificant) effect on A/C performance, I still feel the issue of knowing what proportion of RAF squadrons actually used 100-octane to be quite pointless, even though that was the question starting this thread.

 

[pbehn]

Thanks for putting together this long post. The mass of data as well as its diversity leaves no doubt about 100-octane fueling the RAF during the battle of France.

Since the article from G.Bailey concludes that 100-octane had a marginal (and perhaps insignificant) effect on A/C performance, I still feel the issue of knowing what proportion of RAF squadrons actually used 100-octane to be quite pointless, even though that was the question starting this thread.

If you believe that the introduction of 100 Octane resulted in marginal and even pointless effects on performance then the whole thread has been pointless.

 

[Mori]

If you believe that the introduction of 100 Octane resulted in marginal and even pointless effects on performance then the whole thread has been pointless.

That's were I stand now, correct. There does not seem to be more recent litterature about 100-octane than Bailey's 2008 article, so I'll stick to his conclusions.

But also learned quite a few things on related topics, like 100-octane during battle of France.

 

[pbehn]

That's were I stand now, correct. There does not seem to be more recent litterature about 100-octane than Bailey's 2008 article, so I'll stick to his conclusions.

But also learned quite a few things on related topics, like 100-octane during battle of France.

You dont need anything more than a graph showing the power and performance differences, which you have been shown. The statement is as wrong in 2008 as it was in 1940, such a statement also treats those people long since dead as fools, which they quite obviously werent. Obtaining more power via higher octane fuels and the boost pressures that they allowed was one of the technological competitions during the war.

 

[rochie]

play nice Gents !

 

[Mike Williams]

You dont need anything more than a graph showing the power and performance differences, which you have been shown. The statement is as wrong in 2008 as it was in 1940, such a statement also treats those people long since dead as fools, which they quite obviously werent. Obtaining more power via higher octane fuels and the boost pressures that they allowed was one of the technological competitions during the war.

30 m.p.h. increase isn't bad as per F/Lt I. R. Gleed, of 87 Squadron flying a Hurricane in France on 19 May 1940 and recorded in his book published in 1942 - Arise to Conquer, (Random House, New York 1942) p. 61 :

 

[Mori]

You dont need anything more than a graph showing the power and performance differences, which you have been shown. The statement is as wrong in 2008 as it was in 1940, such a statement also treats those people long since dead as fools, which they quite obviously werent. Obtaining more power via higher octane fuels and the boost pressures that they allowed was one of the technological competitions during the war.

The point about "treating some people long since dead as fool" is for Mr. Gavin Bailey, should he still be contributing to this forum.

About the previously mentioned graph: it is not self-explanatory until you know how to read it. Would you be kind enough to explain what the curves are and what the axis mean, and what conclusion to draw from it written in plain language, if that's not asking for too much?
That's exactly what G.Bailey did when commenting the test data he based his conclusion on. He made it understandable to anyone. The post by M.Williams is also written so that anyone can understand what's meant.

"Ce qui se conçoit bien s'énonce clairement, et les mots pour le dire viennent aisément" (Boileau).

 

[Shortround6]

The situation is at once both complicated and simple.

As in many things be very careful you are comparing like to like.
Which does not seem to be the case.

Page 7 of the excerpt?

"The critical difference can be seen by comparing the time to height results from Table 2 with the comparable figures for the two Spitfires in Table 1 . The adoption of the variable-pitch propeller improved the time taken to climb to 20,000 feet by nearly 4 min. By contrast, the use of100-octane fuel alone only improved the time taken to climb to the same altitude by less than 1 min. This indicates that the adoption of the variable-pitch propeller was four times more beneficial to the rate of climb than the use of 100-octane fuel. In other words, using the same yardstick of the time taken to climb to 20,000 feet, the adoption of the variable-pitch propeller improved Spitfire performance by 33%, while the use of 100-octane fuel only improved it by 6%."

The Spitfire II used a Merlin XII engine that used a slightly higher gear ratio than than a Merlin III. 9.089 compared to 8.588. This means the Supercharger on the Merlin XII needed about 12% more power to drive it than the Supercharger on the Merlin III. Also means that the Mixture was being heated a bit more at the same level of boost which means slightly thinner air (less dense) and the same boost pressure.

British climb rates or time to climb were always done at the 30 minute rating unless it specifically state otherwise.
Neither engine was operating at max boost or rpm for the climb times. Which makes it rather hard to judge the effectiveness of the the higher octane fuel (higher boost) since they weren't using the full available boost the fuel allowed for the climbs.

If you can find a time to climb to 20,000ft (or close) using 3000rpm and 6lbs or 3000rpm and 12lbs boost then you have something to go on.
The Spitfire II was using 8.8lbs of boost ( many planes varied either up or down by several 10ths of pound in boost pressure.)

The Spitfire II could use 6lbs of boost about 1000ft higher than a MK I with a Merlin III could due to the change in supercharger gear ratio.
Now to really screw things up, Neither one of them could hold 6lbs of boost while climbing using non-emergency power. Without the aid of RAM the Spitfire I

Spitfire Mk I N.3171 Trials Report

Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.

www.spitfireperformance.com

Was using 6.4lb at 2600rpm until about 11,000ft and by 20,000ft it was using 1.0lbs of boost.
The Spit II was using 8.8lbs at 2840rpm (2850 nominal) until 10,000ft. 6lbs to just under 16,500ft and had 3.5lbs of boost at 20,000ft.

Maybe the Spitfire II was using the advantage of the 100 octane fuel from 0 feet to about 16,000ft but it was not using much of it. Nothing like the boost in performance that going to 12lbs of boost gave.

Basically that entire example is almost worthless for figuring out the change in performance that 100 octane gave.

Now to fair, 100 octane gave about 0% increase in performance above 16,000ft in a Spitfire in level flight with the 'tit' pressed because the supercharger could not deliver air at more than 6lbs of boost at that altitude even with RAM.

Now
"The performance benefit afforded by 100-octane fuel was only significant at maximum engine power settings at low altitudes for short periods of time, such as providing a decreased length of take off run."
I am not sure that using increased boost for take-off was ever done with the early Merlin engines, regardless of fuel used.
Blenheims with Mercury engines did it. They often filled the inner tanks with 87 octane fuel and the outer tanks with 100 octane fuel for take-off and climb out and then switching to the inner tanks for cruise. Sometimes they shifted back to the outer tanks (100 octane) if they thought combat was imminent. 100 octane did nothing for cruise.


I also find it curious that the difference between British 100 octane fuel and American Military 100 octane doesn't seem to be mentioned in the article. The American suppliers were supplying fuel to British Specifications. The US would not accept US Military 100 octane fuel of 1940 and the US Military would not accept British 100 octane fuel of 1940.
British 100 octane fuel of 1940 would allow more boost than the US Military 100 Fuel. But that is a subject that has gone over in many other threads.

 

[Mike Williams]

Now
"The performance benefit afforded by 100-octane fuel was only significant at maximum engine power settings at low altitudes for short periods of time, such as providing a decreased length of take off run."
I am not sure that using increased boost for take-off was ever done with the early Merlin engines, regardless of fuel used.
Blenheims with Mercury engines did it. They often filled the inner tanks with 87 octane fuel and the outer tanks with 100 octane fuel for take-off and climb out and then switching to the inner tanks for cruise. Sometimes they shifted back to the outer tanks (100 octane) if they thought combat was imminent. 100 octane did nothing for cruise.

You may recall that Spitfires were approved to use 100 octane fuel on 24th September, 1938 "in order to improve the take-off performance of Spitfire aircraft." The change in props should have lessened the imperative to take off with emergency boost.

http://www.wwiiaircraftperformance.org/100-octane/24sept38-spitfire-100oct-approval.jpg

I do recall one case where emergency boost was used for take-off: Colin Gray, Spitfire Patrol, (Hutchinson, London, 1990). pg.59-60

http://www.spitfireperformance.com/54-gray-31aug40.jpg

I was first out on the airfield with my section, waiting for the orders to get into position, and had just turned on the radio in time to hear a panic stricken shout over the R/T, '54 Squadron take off, take off, for Christ's sake take off." I had never heard the controller use this sort of language before, and it was obvious something was very wrong, so I opened up my throttle and for Christ's sake took off. ... Fortunately George, who had not heard the message, realized that something was up or I would never behave in this manner, so he instructed his section to press their emergency boost tits (giving double take off power) and sailed past me before I was half-way down the field.​

That said, I take your point and pretty much agree. In addition, I've posted, here and elsewhere, loads of examples of pilots benefiting from the extra power provided by 100 octane fuel. How can a 30% increase in power not come in handy?

 

[RCAFson]

By the way, 100 octane requires a few twists in the engine, like changing the spark plugs. Once done, is there any issue fueling 87 octane? I believe not, but just asking.

The plugs are specific to the fuel type. However, if you look through encounter reports, squadron diaries, pilot memoirs, etc, if 87 octane fuel was in widespread use by combat units, you would find pilots stating that their low altitude performance was suffering because they were forced to use 87 octane fuel, which deprived the Merlin III of nearly 300hp at 10K ft. Do you really think that a combat pilot, knowing that 100 octane fuel is being used elsewhere in FC, would silently endure that loss of performance, for no good reason?

 

[Mori]

RAF use of 100 octane during the Battle of Britain is well sorted. Less well widely known and understood is RAF use of 100 octane during the Battle of France. Published accounts during the war show the use of 100 octane and its benefits prior to and during the battle of France. Maybe this was forgotten in subsequent generations or the writings about the BoB just eclipsed those of the Battle of France?

Small additional remark about the use of 100 octane during the Battle of France.

In Hough & Richards, "Battle of Britain. The Jubilee History" (1989), one reads:

Jeffrey Quill, the notable Spitfire test pilot, wrote to the authors on 15 August 1988, in response to an enquiry about the introduction of 100 octane fuel: I think it virtually certain that the Hurricane operated in France on 87 octane because I think it was only shortly before the Battle of Britain that we changed over to 100 octane.

Memories of pilots (of anyone actually) is always a source to handle with care. This seems a plain case of a patently wrong testimony.

 

[ThomasP]

Hey Mori,

Here is a marked up version of the Spitfire Mk I graph showing how to read the various lines and numbers. If you have any more questions please ask.

The hatched area in the lower right quadrant of the speed envelope indicates the effect of the increase in boost.

Note that the +30 mph speed increase mentioned in Mike William's post#55 is indicated in the graph.

There are no TTH (Time To Height) or ROC (Rate Of Climb) values in the graph, only speeds for Best Climb, Maximum Economic Cruise, and Maximum Speed (at max available boost. The Best Climb Speed uses a different mph scale than do the Maximum Economic Speed and Maximum Speed.

I do not know if +12 lbs boost was used for climb to any degree during the BoF or BoB, but if so there would have been a significant increase in ROC (+800 fpm?) and decrease in TTH. Just using it for a few seconds during maneuver would have given a significant short term performance increase in ROT (Rate Of Turn) and ability to perform the various acrobatics like rolls and loops without stalling.