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

[Crumpp]

Spitfire Mk I Pilots Operating Notes, dated June 1940:



This is an Inspection and Test Certificate for a specific aircraft with a Merlin Mk III engine. Inspection and Test Certificate is probably the same as an FAA Form 337 allowing major modification for research or testing purposes. Note the document clears a single aircraft by serial number on 28 February 1940. The July of 1940 Spitfire Mk II manual clears the Merlin III engine for use of 100 Octane fuel and notes +12lbs may be used.

That is not the Spitfire Mk I but rather the Spitfire Mk II. There is nothing authorizing the Spitfire Mk I to use +12lbs in any of the Operating Notes.

[41Sqn_Banks]

Originally Posted by Crumpp

The July of 1940 Spitfire Mk II manual clears the Merlin III engine for use of 100 Octane fuel and notes +12lbs may be used.

I think there is a typo in this sentence. Not sure if you mean Spitfire I or Merlin XII.

[Glider]

Crumpp Interesting find, can I ask if you can show the page where it mentins the fuel to be used?
If it doesn't then it would be refering to the early war 87 octane as that was the only fuel available. The date of the Pilots Notes is not a definitive statement as was proved by Kurfursts version of the Mk II pilots notes which had an incorrect date.
Other clues would be the instructions re the prop normally around the mid 20's section and the fitting of armour plate for pilots protection normally around item 40.

Look forward to seeing the above.

PS How are you getting on re the proving of 16 squadrons?

[Crumpp]

The date of the Pilots Notes is not a definitive statement as was proved by Kurfursts version of the Mk II pilots notes which had an incorrect date.

I thought Kurfurst proved someone photo-shopped that version.

PS How are you getting on re the proving of 16 squadrons?

I have not seen anything that proves there were any more by September. What I have seen is misuse of information such as a single Inspection and Test certificate to build a case the entire RAF was using 100 octane or failure to explain an illogical use to reserve ratio.

Do you know what a Cylinder head spigot is?

In order to use +12lbs on the Merlin engine, you had to replace the heads with a new design with a increased spigot depth of .020. There were two authorized heads being manufactured to convert engines. One could use the existing rings while the other required a specific set of rings to be installed. Once that was done, the fuel metering system had to be modified. You can figure they would have had a 4 to 1 stock of heads before they started modifying aircraft. They would maintain that ratio even if it limited the size of the force they could convert.

In that memo dated 20 March 1940, it states this will be done as service maintenance. That means it was done on the equivalent of an annual inspection. So depending on when the aircraft made its service maintenance inspection is when it would be modified. Of course, Air Forces generally do it on an hourly basis such as 100 hrs, 200 hrs, 500 hrs up to 2000hrs. The Focke Wulf FW-190 was a 10/200hrs schedule for example. That is a 200 hour inspection can be done 10 times before the aircraft is sent depot level maintenance for overhaul.

[Al Schlageter]

Originally Posted by Crumpp

I have not seen anything that proves there were any more by September.

Quite dodging the question. What are squadron numbers for these 16 squadrons.

Fill in the blanks __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ .

[NZtyphoon]

Originally Posted by Crumpp

You can figure they would have had a 4 to 1 stock of heads before they started modifying aircraft. They would maintain that ratio even if it limited the size of the force they could convert.

In that memo dated 20 March 1940, it states this will be done as service maintenance. That means it was done on the equivalent of an annual inspection....So depending on when the aircraft made its service maintenance inspection is when it would be modified.

* AP1590B/J.2-W (attached) 20 March 1940 (the "memo") states that the modifications were "already being done" as service maintenance, with no mention of it being done as an "annual inspection" (nor does it mention the service intervals of aircraft) - the "annual inspection" is pure speculation on your part, with no evidence, as per usual.

* AP1590B/J.2-W goes on to say that "Newer engines will already have Mod.No.Merlin/136 embodied" meaning all production engines from March 1940 did not have to be modified because Mod No. Merlin/77 (modified spigots Merlin/64 plus modified piston rings) was incorporated on the production line as a production modification (Mod.No. Merlin/136). But you didn't mention that inconvenient fact - just another example of your misreading/misuse of documentation.

How many Merlin IIIs built before March 1940 would have still been in operational use by July? The modifications Mod/64,77 & 154 also applied to Merlin IIs not many of which would have been in service by July 1940.

Much of the rest of AP1590B/J.2-W describes modifications needed to the cut-out valve, then it sets out the engine's operating limits and is a general note for pilots.

* The comment about a "4 to 1 stock of heads" is pure blather and speculation on your part, with no documented evidence, and with no relevance to AP1590B/J.2-W.

Once again, for your benefit Crumpp:

*Explain how the RAF ensured that only 16 squadrons used the fuel - with documentation. Explain why at least 30 Squadrons - Hurricanes Defiants and Spitfires - report the use of 100 octane fuel when you insist only 16 squadrons used it - with documentation please.

*Explain what happened to at least 52,000 tons of 100 octane fuel with documentation.

*List the 16 squadrons authorised to participate in trials, with documentary evidence showing they were only participating in trials.

*Prove that the Merlin III was designed for only 400hp - with documentation.

All the rest is a smokescreen, showing your total lack of evidence for anything you say.

Originally Posted by Crumpp

I have not seen anything that proves there were any more by September. What I have seen is misuse of information such as a single Inspection and Test certificate to build a case the entire RAF was using 100 octane or failure to explain an illogical use to reserve ratio.

The only one misusing/misrepresenting information is your good self -

* You have not explained, for example, why the "use to reserve ratio" of Other Grades of aviation fuel, including 87 Octane, were lower during the battle than 100 Octane fuel, reserves of which continued to increase throughout?

Please answer these specific questions instead of dodging them, as per usual.

[28_Condor]

The writer Michael Korda, who served in the RAF, said in his latest book ("With Wings Like Eagles") that the RAF as a whole was served by american 100-octane fuel since 1939. And that was the advantage used against the German fighters that had fuel injection (but 87 octane fuel).

The British only really manufactured the fuel of 87 octane. It was Dowding who insisted that the British government to acquire the fuel from the Americans.

[Robo.]

According to some sources, the test certificate (this 'Page 40' document) is from testing of Merlin III improvements - of what has later become the Merlin XII. Unfortunately, without the rest of this paperwork (previous 39 pages) we can only assume what exactly is that all about I am afraid...

Anyway, knowing RR habit of testing and 'breaking' engines while improving parts that fail first to get more power, this makes perfect sense to me. Ratings of both Merlin XII and Merlin III are well documented and researched - Merlin in perspective pg. 155 and onwards states all ratings according to improvements along from III to XII:

R.M.1.S. (Merlin III)

combat power: 1310hp, 3000rpm, 9000ft., +12lbs
(combat power: 1440hp, 3000rpm, 5500ft., +16lbs - Sea Hurricane only)
take off: 880hp, 3000rpm, +6.25lbs.
cruising: 2600rpm, +4.5lbs.
climbing: 2600rpm, +6.5lbs.

R.M.2.S. (Merlin III, as R.M.1.S. but with increased take-off power on 100 octane fuel, superseded by the use of combat ratings on R.M.1.S.)

combat power: 1000hp, 3000rpm, 15500ft.,+6.25lbs.
take off: 1000hp, 3000rpm, +8.25lbs.
cruising: 2600rpm, +4.5lbs.
climbing: 2600rpm, +6.5lbs.

R.M.3.S. (as Merlin IV but higher supercharger gear ratio (note was 8.588 on Merlin III, is 9.089 on Merlin XII) and 100 octane fuel. For Spitfire II)

combat power: 1280hp, 3000rpm, 10500ft.,+12lbs.
take off: 1175hp, 3000rpm, +12.5lbs.
cruising: 2650rpm, +7bs.
climbing: 2850rpm, +9lbs.

R.M.4.S. was regarding further improvements on Merlin XII, but was never production type; superseded by Merlin 45

[NZtyphoon]

Originally Posted by 28_Condor

The writer Michael Korda, who served in the RAF, said in his latest book ("With Wings Like Eagles") that the RAF as a whole was served by american 100-octane fuel since 1939. And that was the advantage used against the German fighters that had fuel injection (but 87 octane fuel).

The British only really manufactured the fuel of 87 octane. It was Dowding who insisted that the British government to acquire the fuel from the Americans.

The British were manufacturing the iso-octane needed to produce 100 Octane fuel at Heysham, Billingham and Stanlow in Britain, while there were other sources of 100 Octane fuel from the Dutch East Indies, Trinidad etc, mostly from the British Shell Company and Anglo-American Oil Co, so it's not correct to say that all 100 Octane fuel came from the United States. (see attachments)

For Crumpp's benefit: the Trimpell article states that by 31 July 1940 there were 384 Spitfires in 19 Squadrons using the fuel, as well as PR Spitfires -

* On 13 July the OOB's show 19 Spitfire squadrons; in addition there are 31 Hurricane squadrons and 2 Defiant.

Crumpp can sneer all he likes, but this alone scuppers his blind addiction to 16 fighter squadrons.

[41Sqn_Banks]

See this post for the relevant pages of AP1565A Vol. I that cover +12 Boost and 100 Octane.

http://forum.1cpublishing.eu/attachm...9&d=1332111633
http://forum.1cpublishing.eu/attachm...0&d=1332111638
http://forum.1cpublishing.eu/attachm...1&d=1332111649
http://forum.1cpublishing.eu/attachm...2&d=1332111659
http://forum.1cpublishing.eu/attachm...3&d=1332111666

Note Sec. 2 Para XII where the increase of boost to +12 is mentioned. Note Sec. 8 Para 7 the use is "authorized" for short period and when 100 octane is used. Also note the "List of Content" of Sec. 8, it shows Sec. 8 was issued with A.L. 6 in July 1940.

Originally Posted by Crumpp

In order to use +12lbs on the Merlin engine, you had to replace the heads with a new design with a increased spigot depth of .020. There were two authorized heads being manufactured to convert engines. One could use the existing rings while the other required a specific set of rings to be installed. Once that was done, the fuel metering system had to be modified. You can figure they would have had a 4 to 1 stock of heads before they started modifying aircraft. They would maintain that ratio even if it limited the size of the force they could convert.

Note that Sec. 8 Para 7 also refers to AP1590B Vol. I (manual of Merlin II and III) for the required modifications. IIRC in this manual only Mod 154 (modification that limits the boost to +12) is mentioned as required and the other modifications are recommended. I will look these pages up later. EDIT: The manual states that both mods are required.

Originally Posted by Crumpp

The July of 1940 Spitfire Mk II manual clears the Merlin III engine for use of 100 Octane fuel and notes +12lbs may be used.

Please correct this statement. It's unlikely that the Spitfire II manual (which has a Merlin XII engine) clears anything for the the Merlin III engine.