Inaccurate performance data for BOB fighters in COD comparing to RL data

[Seadog]

There are several errors in the above excerpt. The Merlin X had a two stage SC and was not a Merlin III modified to run on 100 octane.

British Tanker losses in the first year of the war were quite low.

OTOH, it shows clearly that the Merlin III could be run for long periods of time at 12lb/3000rpm. 10 hours in 1938 engines and 20 hours in later engines.

[Seadog]

http://i38.photobucket.com/albums/e1...00octane_1.jpg

and this is a prewar planning document, and we all know that RAFFC made a wholesale conversion to CS props and 100octane fuel in the spring of 1940 in response to wartime events, especially the improved performance of the Me109. Conversion to 100 octane without changing over to CS props was almost pointless, but a March 1939 planning meeting could not have envisaged the largescale changes that would be required by Spring 1940.

[Glider]

Originally Posted by CaptainDoggles

Those two images you attached speak pretty clearly to me, and say that the DTD230 (which I assume is 87 octane?) is not simply "for aircraft passing through" but rather the station must include aircraft passing through when calculating its total consumption requirements for DTD230. In other words, the station must take into account not only its own consumption of 87 octane but also the consumption of any aircraft that might be passing through.

In fact the first scan states quite clearly that the decision to eliminate their holdings of DTD230 should not be taken as a precedent, so to me this is in fact quite compelling evidence that the RAF had not converted all its aircraft to 100 octane (at least in April of 1940 when the document is dated).

This might clarify the position. The first paper you have seen before and is the Summary of the Conclusion of the 5th Meeting of the Oil Committee. You have seen this before its where the Chief of the Air Staff has requested that fighters and Blenheim units be equipped with 100 Octane.

The second paper is the actions from the 5th meeting of the Oil Committee for the 6th Meeting. Here the statment is quite clear that Blenheim units in No 2 Group were to switch to 100 Octane.

The previous two papers I posted highlighted that four stations were to be totally equipped with 100 Octane and the others were to keep one tank of 87 Octane. I should add that these were from the 6th meeting of the Committee. I should also add another paper from the 7th Meeting of the Oil Committee where they confirm that the fighter units concerned had been stocked with the 100 Octane Fuel and that the Air Minestry had been impressed with the way that the task had been handled.

You can of course read those previous papers how you wish, but to me when it says to keep one sixth of the fuel as 87 Octane and five sixths 100 Octane and we know that some of that 87 Octane is for visiting aircraft then operations are going to be on 100 Octane. Put all the papers together they tell me that all Blenheim units in No 2 Group are going to use 100 Octane on operations. I emphasise all, not two squadrons.

You may well consider me to be childish but I have produced original documentation to support my case.

[Crumpp]

You may well consider me to be childish but I have produced original documentation to support my case.

The meeting notes you posted seem to confirm that Bomber command was using 100 Octane in the Blenheim's.

However it clearly states that Fighter Command was still not clear whether or not 100 Octane could even be used in Hurricane and Spitfire aircraft.

OTOH, it shows clearly that the Merlin III could be run for long periods of time at 12lb/3000rpm. 10 hours in 1938 engines and 20 hours in later engines.

Yeah...that is the times from the endurance trials, Seadog. It was 10 hours total time. That 10 hours at +12lbs was 5 minutes at a time with a 20 minute rest period in-between. It was not 10 hours straight at +12lbs....

[Glider]

Originally Posted by Crumpp

The meeting notes you posted seem to confirm that Bomber command was using 100 Octane in the Blenheim's.

However it clearly states that Fighter Command was still not clear whether or not 100 Octane could even be used in Hurricane and Spitfire aircraft.

Re Fighter Command you are correct and from the papers it was clear that this was totally unexpected, after all the engines had been tested and aircraft equipped with them for performance testing. It was the last thing they expected and was dealt with as the following paper trail explains.

In the Summary of Conclusions of the 6th Meeting the following action was given to RDE 1 who was a Mr Tweedie, the action being to clarify the position with Fighter Command. In the 7th Meeting it was noted that the use of this fuel had been made clear to Fighter Command and that the Units had been equipped with the 100 Octane Fuel.

[Viper2000]

Originally Posted by Crumpp

Yeah...that is the times from the endurance trials, Seadog. It was 10 hours total time. That 10 hours at +12lbs was 5 minutes at a time with a 20 minute rest period in-between. It was not 10 hours straight at +12lbs....

I don't think any aeroplane of the period had enough fuel to run for 10 hours straight at +12, so I don't think you have to worry too much about the engine not getting rest between bouts of torture...

[Crumpp]

I don't think any aeroplane of the period had enough fuel to run for 10 hours straight at +12, so I don't think you have to worry too much about the engine not getting rest between bouts of torture..

The endurance trials were conducted over the course of many flights. It was not done on a test stand but on a Hurricane IIRC. The airplane flew multiple flights to accumulate time and the test ended when the engine failed ~10 hours of operation at +12lbs.

[Crumpp]

In the 7th Meeting it was noted that the use of this fuel had been made clear to Fighter Command and that the Units had been equipped with the 100 Octane Fuel.

Yes, it states the units concerned have been stocked.

What are the units concerned?

[Glider]

It doesn't say but its a common phrase to say in this situation. We do know that the Chief of the Air Staff had asked for fighter units to be equipped with 100 Octane. This request wasn't limited to Group or squadron or any other kind of boundary so I believe that the units concerned are the Fighter units.
I admit that its the sort of ambiguity that some people will try to build a lot on, but I cannot help what a senior civil servant wrote down seventy years ago and have to live with the consequences.

[Kurfürst]

Originally Posted by Glider

We do know that the Chief of the Air Staff had asked for fighter units to be equipped with 100 Octane. This request wasn't limited to Group or squadron or any other kind of boundary so I believe that the units concerned are the Fighter units.

No, that's a quite untrue representation of the doucment. The document actually says: "At the last meeting AMSO referred to a proposal that certain Fighter and Bomber Squadrons should begin the use of 100 octane fuel..."

There's no uncertanity in here. You simply misquote the document.

Gilder, do you have the complete file?