Spit IIa is now so much more inferior to the 109

[Seadog]

RR was using 100 octane fuel for testing and development from 1937 onward:

Appendix IV

The Merlin and 100 Octane Fuel

Questions have been asked on the early use of 100 octane fuel and in particular on its influence during the Battle of Britain. Until 1937 the Merlin had been confined to 87 octane fuel to DTD230, because it was felt that in the event of war 100 octane. which was being developed by the Americans, might not be available to the British. This anxiety arose from the American Neutrality Act. which could prevent supplies being shipped to this country. Probably as the result of a paper by Rod Banks in January 1937, the Air Ministry agreed to proceed with engine development to take advantage of high octane fuel.

At that time the American 100 octane did not suit the Merlin because it lacked a good rich mixture response. Esso undertook the development of a suitable fuel, using 10% aromatics, and the driving force behind this was Dr Bill Sweeney whose fuel mix became known as Sweeney's Blend. Three months before the start of the war an Esso tanker Beaconhill delivered a full cargo of the special 100 octane fuel to Britain and by March 1940 the decision had been taken to switch Fighter Command to this type. Bomber Command changed over early in 1941.

The effect of 100 octane was to allow the Merlin to run at 12lb boost putting up the power of the Merlin III from just over 1000 hp to 1300 hp. However, this high power was obtained at between 8 000 and 9 000 ft and above this altitude, at a max combat power rpm of 3000, the boost and, therefore. power advantage was progressively declining. On 87 octane fuel and 6lb boost, using 3 000 rpm, the maximum power was 1030 hp at 16 000 ft. At this point on either fuel the engine was giving the same power, so above this height 100 octane fuel offered no advantage. The majority of the air fighting in the Battle of Britain was at 18 000 ft and above and the engine in most common use was the Merlin III. The gain in performance from 100 octane was entirely at lower altitudes. Before the end of the Battle Spitfire IIs with Merlin XIIs were in service, with the supercharger gear ratio increased from 8.58 to 9.09:1 giving a better full throttle height at 12lb boost and a small number of Hurricane IIs fitted with two-speed Merlin XXs. with ratios of 8.15 and 9.49:1 for MS and FS gear, these engines could take much greater advantage of 100 octane fuel and in the case of the Merlin XX were capable of maintaining 12lb boost to over 20 000 ft at 3 000 rpm, thanks to the new central entry supercharger.

This set the pattern and without 100 octane fuel the further power development of the Merlin would not have been possible. As an example the two stage blown Merlin 66 was capable of over 1600 hp at 16000 ft using 3000 rpm and 181b boost. The pioneering work of Esso to produce a suitable 100 octane fuel was the key to the high power Merlins in all spheres of operation and it was not until 1944 when 150 grade fuel became available that further advances in boost pressure to 25lb were made, allowing over 2 000 hp to be used in squadron service.

The opening paragraphs of this appendix are the result of information supplied to Michael Evans, Chairman of the Rolls-Royce Heritage Trust by Alexander Ogston, Historian of the Wings Club in New York, who has had a lifetime in fuel technology and a conversation which I had with Rod Banks shortly before his death.

The Merlin in Perspective, p87.

[41Sqn_Banks]

Originally Posted by Crumpp

Let's see the whole publication because they do not match at all. Either the warning about 100 Octane is a technical update added at a later time or it is not from the same document.

Of course it is not the same document, as said it's from the 1st edition. If you read the preface of the 2nd edition you will notice that it has been "revised and rearranged in convenient order and grouping". That's why they are not comparable.



This is the whole page where the 100 octane limitation was taken from.
http://forum.1cpublishing.eu/attachm...0&d=1334727256
http://forum.1cpublishing.eu/attachm...1&d=1334727263

And it's perfectly in line with the 100 octane limitations of various Merlin engine manual from January 1939 to November 1940:

January 1939: http://forum.1cpublishing.eu/attachm...0&d=1334682385
April 1940: http://www.wwiiaircraftperformance.o...erlin3-pg6.jpg
March 1940: http://www.spitfireperformance.com/ap1590b.jpg
November 1940: http://forum.1cpublishing.eu/attachm...5&d=1337196053

These are several other quotes from the 1st edition of Pilot's Notes General.
http://forum.1cpublishing.eu/attachm...4&d=1334772058
http://forum.1cpublishing.eu/attachm...8&d=1334956606
http://forum.1cpublishing.eu/attachm...6&d=1335714870
http://forum.1cpublishing.eu/attachm...2&d=1326733398

I'm sorry, I do not intend to provide a whole digital copy, it's a very rare item. Not sure if The National Archives has one and I've never seen it somewhere else. You can PM me if you have something pleasurable to offer as an exchange.

[Kwiatek]

Originally Posted by Ernst

Are the SPITFIRE FMs at UP 3.0 RC4 yours?

Probably not my FM's ( for 109s, Spits, Fw 190s, P-51 etc) was up to UP 2.X versions.

[Bokononist]

Originally Posted by CaptainDoggles

Spit is only worse if you are one of the noobs flying around on the deck, turning circles kicking up dust.

My wingman and I confronted some Spitfires up high over England two nights ago and they were extremely formidable.

Can we please put this tired topic to rest?

Good pilots are good pilots for sure Doggles, and I class myself as a distinctly avarage pilot at best! The issue though is caused by the fact that this a simulator designed to model the battle of Britain which was fought with Hurricanes and Spitfires (both 1 and 2s) all modified for 100 octane fuel. What we have are planes that are not the ones that fought this battle. Whatever the standard of pilot is not really relevant here, the reds are flying the wrong planes for the BoB. Of course people are annoyed, and with the game in a state of flux at the moment those people want to bring the subject to the attention of as many people as possible, in the vain hope that the devs will acknowledge and correct this glaring historical error.
Boko.

[Kwiatek]

Originally Posted by Bokononist

Good pilots are good pilots for sure Doggles, and I class myself as a distinctly avarage pilot at best! The issue though is caused by the fact that this a simulator designed to model the battle of Britain which was fought with Hurricanes and Spitfires (both 1 and 2s) all modified for 100 octane fuel. What we have are planes that are not the ones that fought this battle. Whatever the standard of pilot is not really relevant here, the reds are flying the wrong planes for the BoB.
Boko.

Performacne of british fighters in Clod now not even match historical performacne of these planes at 87 octan fuel not mention 100 octan fuel boost

[KG26_Alpha]

Ok

Again the 100 octane is getting into every thread lately no matter what the subject matter is.

You guys are going around in circles with it, please keep it all in one place at least, it's looking like spam with the same data copy and pasted everywhere.

I re-opened the performance data thread for sensible factual data discussion last week, after a cooling off period, it looks like it's back on track for now.

http://forum.1cpublishing.eu/showthread.php?t=20110





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