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

[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?

[Glider]

Clearly this posting (note not a paper) forms the core of the argument that RAF Fighter command were not fully equipped with 100 Octane so I will look at it in detail.

Originally Posted by PipsPriller on Jul 12 2004 at [url
http://www.allaboutwarfare.com/forums/index.php?showtopic=230&st=0&start=0][/url]
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 what were considered reasonably 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.

Fighter Command started converting its aircraft before March. An exact date I do not have but attach two documents showing that two squadrons were equipped by 16th February, the probability is that there were others but I cannot confirm that.

By the time of the invasion of the Low Countries by Germany in May 1940 the RAF had converted approximately 25 % of its total fighter force to 100 octane fuel use. The subsequent escalation in air activity and demands placed upon Fighter Command over the next two months put great strain on both the 100 octane fuel stockpiles and aircraft modified to use the fuel. Against the backdrop of total war the RAF found that its reserves of 100 octane fuel was well below the level considered necessary for widespread use, for any sustained length of time.

The 25% figure by May 1940 I cannot confirm or deny so will not comment, but the rest of this section I do fundamentally disagree with. In December 1939 stocks of 100 Octane were 202,000 tons and by August 1940 stocks were at 404,000 tons (documents are attached). We know that in June – August the average consumption was 10,000 tons a month (document attached).
The questions I suggest that we need to ask are:-
1) If you have what is in effect a three and a half year stockpile, is this a strain, let alone a great strain on the stockpile. In my opinion it isn’t a strain at all, it’s barely noticeable
2) The implication that the RAF fought the BOB with only 25% of its aircraft converted is unbelievable. Think of the practical implications, squadrons with mixed fuels and mixed performances, what are new build aircraft 100 octane or 87 octane, engines are changed and replaced, again are these 100 octane or 87 octane. Why hasn’t anybody mentioned this in all the hundreds of books written on the BOB?

Two actions were immediately undertaken by the British War Cabinet in May to resolve the looming crisis. Firstly 87 octane fuel was deemed the primary fuel source to be used until further supplies could be discovered and delivered in sufficient quantities to allow the Merlin conversions to again take place. Those existing fighters already so converted (approximately 125) would continue to use what supplies of 100 octane were available, but all other fighters that had not been modified to continue with the use of 87 octane (of which there was more than adequate supply). The second action was for the British Government to contract the Shell Oil Refining Company to assist the British-controlled Iraqi Petroleum Company at Kirkuk to produce 100 octane fuel. This arrangement proved quite successful as production was quickly converted to 100 octane fuel.

The British War Cabinet didn’t discuss 100 Octane at all in May and as a result no decisions were made. I spent a day in the NA going through all the papers for the meetings, the meeting notes and the actions resulting, and Fuel of any kind was not discussed. I should add that in May 1940 the War Cabinet met almost daily and it was a huge amount of paper, literally hundreds of sheets. There were some interesting unexpected gems, the one I liked most was a decision to take over a number of Swedish Naval vessels by force and include them in the Navy. The First Sea Lord decided that while additional vessels were always welcome, giving Germany an excuse to invade Sweden to protect them from the British was too high a risk.

The first Middle East shipment of 100 octane fuel arrived in Portsmouth on 12th August, with a further two deliveries in September and four in October. Although too late to allow widespread conversion for the use of the fuel the deliveries did ensure that from this point on Britain would not be lacking in 100 octane fuel levels. With the newfound supply RAF Fighter Command again embarked upon a Merlin II and III conversion to 100 octane use from late September, finally achieving 100% conversion of its fighter force by the end of November in 1940.

Given that large quantities were not available until late August, the volume of usage/week of 87 Octane must be far higher than that quoted for 100 Octane

I am afraid that this is incorrect. The previous paper giving the stocks in 1940 show a strong steady increase, it certainly wasn’t the case that they had to wait until August for additional stocks. There is no indication anywhere that the RAF stopped converting fighters in May, fought the BOB with 125 aircraft modified for 100 Octane and then re started converting the aircraft in late September.
In fact the stocks had reached such a level in August that the rest of the operational aircraft in the RAF were authorised to start using 100 Octane (paper attached on following posting).

I came across it when I was in fact researching another subject (Dutch East Indies Fuel levels prior to the Japanese Invasion) at the Australian War Memorial Archives.

It's from a document, copied to the Australian Military Commission in England in February 1941, by Roll Royce to Lord Beaverbrook outlining past, current and proposed changes to the Merlin; and factors that affect its performance.

It was quite an interesting paper actually, even though I found it to be a very dry subject.

I am afraid that no one has seen this paper so cannot comment on the sources for the above posting.