[Crumpp]

Unless you can provide a print run history for the manual it's all guess work.

Winny, it is not guesswork. It is what the Operating Notes say for every edition until we get to January 1942.

Could have a look at this as well, won't be for a month or so though.

That would be nice if you could do that and let us know what you find.

Crumpp your theory require that in January 1942 at least one operational squadron used at least one Spitfire I aircraft.
Otherwise the restriction for operational units to 100 octane noted in the Pilot's Notes would be obsolete and by your theory would have been instantly removed and changed to "all units 87 octane fuel".
Please name at least one operational Squadron that used at least a one Spitfire I aircraft at that time.

Why does that matter?

It is a fact the manual was reprinted in January 1942 and it is a fact the fuel changeover to "All Operational Units" is important enough to be added to Paragraph 1, Operating Limitations.

The 100 Octane fuel changeover is important enough to make it into every Operating Notes, Paragraph 1, Operating limitations when it occurred.

For example, the Hurricane II Operating Notes dated September 1943 clearly list 100 Octane as the ONLY fuel to be used:



It will note in paragraph 1 the fuel options when 100 Octane becomes common and it will note when all operational units will use the fuel, and when it is the only choice.

It is the operational documentation and not logistical!!

Now, it might not be the exact month because there is some lag time and technical orders will cover that short time period.

you will not see technical orders that are applicable to operational units that do not make it into the new edition.

It is really simple. We have a 1939 edition and we have a June 1940 edition with no changes to paragraph 1, Operating Limitations. That fact tells you 100 Octane was not in common use. It was in use but it was not the most common operational fuel in the RAF at that time.

In between that time we have a technical order to AP1590 which is the engine series and not the airframe series. It makes a difference in aviation and there are plenty of engines that modifications are not approved in specific airframes. There will be an order approving that engine modification for the specific airframe.

For example:

Why isn't the Mooney M-20-C (or Piper Comanche) approved?


A. The Mooney and Comanche both experienced vapor lock problems when they were tested. We solved the vapor lock problem, but could not overcome pneumatic lock. Pneumatic lock takes place when the fuel boils as it enters the carb. The engine then dies due to an overrich mixture. This is just the opposite of a vapor lock where the engine quits or runs poorly due to a lean mixture. The better an airplane performs, the more difficult it is to get it through the flight test program.

Q.If the Apache with 150 or 160 hp engines is approved, then why isn't the Apache with the 0-540 235 hp "B" model engines approved? These engines are listed as approved in your website.


A. The 235 Apache was flight tested and failed the flight test due to vapor lock. At that time if an airframe failed the flight test it was washed out and we went on to the next airplane. There are numerous examples of airframe/engine combinations which would appear to be approved since they have STC's individually, but may not be approved in conjunction with each other either because they failed the flight test or were not tested at all.

http://www.autofuelstc.com/autofuels...Mogas_FAQ.html

I don't know the specific explaination in the case of 100 Octane as too why the large lag time between the engine approval and the airframe operating limitations but I do know that is a flag to anyone knowledgeable in airplane maintenance for claims of widespread general use.

I would get the editions to the Operating Notes and throw away any squadron logs that do not specifically state "100 Octane Fuel in use".

You will have good factual picture on the timeline for the fuels operational use if you do that.