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

[NZtyphoon]

Originally Posted by Kurfürst

Indeed. I don't think anybody has doubts that 100 octane was used in a number of FC's - and also BC's Squadrons., as a number of Blenheim Squadrons (3 or 4 I believe), were also issued with the fuel. Which is why NYTyphoons 'calculations' are flawed and be considered at best for their entertainment value, as he ignores all bombers with many times the consumption and requirement of a fighter squadron, as well as training, moving flights and engine manufacturer demands, which are are simply ignored.

Note what I said:
NB: Not all aircraft returned with empty tanks and RAF policy was to refill each aircraft as soon as possible after landing, or each evening or early morning, to avoid vapour traps.

Blenheims were the only other aircraft known to have used 100 Octane fuel, albeit only in their outer wing fuel tanks, making things complicated for the poor pilots. (Warner, The Bristol Blenheim:A Complete History 2nd ed, page 100.)

Merlin III & XIIs could still use 87 octane fuel, hence training flights and other secondary flight duties, such as delivery, ferry flights, etc could use 87 octane fuel instead of 100.

Other aircraft known to have been using 100 Octane fuel were a small number of Beaufighters and PR Spitfires.

Westland Whirlwinds still used, and continued to use 87 Octane right through their operational lives.

Originally Posted by Kurfürst

But the evidence to somewhat sensational claim that 100 octane was the only fuel issued is still sorely lacking and is directly contradicted by a number of primary and secondary sources....

Nor did I say anywhere only 100 Octane fuel was issued. And where are KF's primary and secondary sources? The main primary sources "presented" by KF are a mysterious Australian/Beaverbrook paper which no-one apart from KF and "Pip" can find (The Australian National Archives themselves cannot find it), and some pre-war planning papers.

Originally Posted by Kurfürst

The trend shown in the consumption of 87 octane and 100 octane fuel is, however intererting. It is clear that about 2/3s of the fuel consumed during the Battle was 87 octane (by all Commands) and 1/3 consumed was 100 octane (by Fighter and Bomber Commands).

All KF is saying is that large numbers of aircraft in other commands were using 87 Octane. Big deal.

Originally Posted by Kurfürst

Checking the trend lines of operational (combat) Fighter sorties and 87 octane consumption during the Battle is interesting. When Fighter Command flew a lot of sorties, 87 octane issues also increased, when Fighter Command flew less of sorties, 87 octane demands decreased, with some delay of course. I think the conclusion is quite obvious.

Yup, there were things like training flights, delivery flights, ferry flights and other second-line duties which naturally increased at times when the frontline units were operating more intensively.

Originally Posted by Kurfürst

Another interesting trend is that 87 octane issues suddenly plummeted during early october, while 100 octane issues increased. This is in line with Pips summary of the Australian paper, which notes that Fighter Command only switched completely over to 100 octane in the late automn 1940.

Meaning FC switched to 100 Octane fuel for secondary as well as frontline duties? Seeing as no-one else apart from KF and "Pip" has seen this paper, and it is missing from the Australian National Archives I guess we have to take his word for it...

Originally Posted by Kurfürst

Its also completely in line with what an unquestionably reputable secondary source, Morgan nad Shacklady's ultimate Spitfire book, 'Spitfire: The History' notes about the initial uncertainity of 100 octane shipments (as all 100 octane had to be imported from overseas).

Convoys started operating in September 1939; the most important were the HX convoys which sailed from Halifax to (mainly) Liverpool. The first - HX.1 - sailed on 16 September 1939. Referring to http://www.convoyweb.org.uk/hague/index.html
The HX convoys incorporated cargo ships, some of which carried aviation fuel, and tankers: many of the latter had sailed from refineries in the West Indies and America. The BHX series sailed from Bermuda, starting in May 1940 (BHX.41), and joined the main HX convoys in Halifax. Some of the tankers from the HX convoys diverted to French ports, enough to supply the RAF fighters in France.

From the HX series of convoys alone (HX 11, 13, 31, 33-35, 40, 43, 49, 55, 57-59, 64-68, 70, 73, 76) 44 tankers carrying AVGAS arrived in British or French ports; one tanker was destroyed by a mine in the Bristol channel. This contradicts the assertion in Shacklady and Morgan that ...large numbers of tankers were sunk by German submarines...

Another reputable secondary source is "Oil" by Payton-Smith which, as noted, is the official war history. He notes that "...in the summer of 1940 there was a surplus of these ships (tankers) because of the incorporation into the British merchant marine of tanker fleets from countries over-run by Germany." pp. 128–130.

Originally Posted by Kurfürst

It also refers to the fact that RAF was intending to initially equip 16 fighter Squadrons and 2 bomber Squadrons with 100 octane, which is again underlined by the memo of the Fuel Commitee's meeting, noting that the selected fighter Squadrons and Blenheim Squadrons have been converted, the memo of which was summarized in a 'doctored' textus on Mike William's site to further the site's agenda.

This memo was a planning paper from 16 March 1939 , based on a pre-war assumption that US supplies would be denied to Britain in wartime, limiting the numbers of front-line units able to use the fuel.

In "Oil" (Official Second WW history) Payton-Smith said:

"By 1939...The prospects of securing sufficient supplies of 100-octane fuel in addition to the 87-octane petrol required for non-operational flying looked doubtful...(he goes on to state on page 57)...It was true that by 1939 it seemed increasingly unlikely that American supplies would be withheld. But to have accepted anything less than absolute certainty, to have depended on the goodwill of foreign suppliers to meet the essential needs of the Royal Air Force, would have been a radical break with traditions that had governed British oil policy since long before the First World War."

Meaning that the pre-war planning papers quoted by KF were being conservative in their estimates, as per a long held tradition.
Payton-Smith went on to say:

"...this problem (supply of 100 Octane aviation fuel) disappeared; production of the new fuel in the US, and in other parts of the world, increased more quickly than expected with the adoption of new refining techniques." pp. 259-260

Interesting how KF resorts to pre-war planning documents to say what happened up to 16 months later, during the Battle of Britain, yet cannot provide primary documentation to prove that the situations discussed up to two years earlier actually eventuated in 1940. And his assertions about "doctored" documents when his own documentation is so shoddy and questionable?

Originally Posted by Kurfürst

Also of interest that the RAF wished to build up a reserve of 800 000 tons for precaution, which couldn't be met in 1940.

Proving nothing really, except that in wartime pre-war plans can change. There was still more than enough 100 Octane fuel consumed by FC, and some Blenheims during the Battle to allow all operational sorties to be flown on this fuel alone.

Interesting to note that Merlin engines using 100 Octane fuel were being built in 1938, as well as C.P propellers

http://www.flightglobal.com/pdfarchi...0-%203453.html

[lane]

Hi NZtyphoon:

One small correction if I may regarding the Westland Whirlwind:

[lane]

Just for fun whilst on the subject - from Flight, March 28, 1940


From IWM: 19 Squadron, Fowlmere, Sept. 1940

[ACE-OF-ACES]

19 Squadron, Fowlmere, Sept. 1940


Nuff said imho

[Skoshi Tiger]

Originally Posted by ACE-OF-ACES

19 Squadron, Fowlmere, Sept. 1940


Nuff said imho

details of plane in picture from http://www.spitfires.ukf.net/p004.htm

P7420 IIa CBAF MXII 6MU 16-9-40 19S 26-9-40 flew into tree nr Boxford Sussex Sgt Roden killed 15-11-40 SOC 23-11-40 FH44.40

[NZtyphoon]

Originally Posted by lane

Hi NZtyphoon:

One small correction if I may regarding the Westland Whirlwind:

In Victor Bingham "Whirlwind: The Westland Whirlwind Fighter (Airlife Publishing, 1987) he wrote that in April 1940 the Director of Design/Research and Development in the Air Ministry, W Farren, commented that it was wrong that one of the latest types of fighter aircraft (the Whirlwind and its Peregrines) was only rated to use 87 Octane fuel instead of 100. (p.36)

The photo is of a 137 Sqn "Whirlybomber" from at least mid-to late 1942, so is it possible that the R-R Peregrine was rated to use 100 Octane by then?

[lane]

Originally Posted by NZtyphoon

In Victor Bingham "Whirlwind: The Westland Whirlwind Fighter (Airlife Publishing, 1987) he wrote that in April 1940 the Director of Design/Research and Development in the Air Ministry, W Farren, commented that it was wrong that one of the latest types of fighter aircraft (the Whirlwind and its Peregrines) was only rated to use 87 Octane fuel instead of 100. (p.36)

The photo is of a 137 Sqn "Whirlybomber" from at least mid-to late 1942, so is it possible that the R-R Peregrine was rated to use 100 Octane by then?

Thanks for the info from Bingham's book. I don't know much about the Whirlwind, so I'm going to see if I can find a used copy. I appreciate the tip. I too figured the photo of the Whirlwind and bowser to be a 137 Squadron Whirlwind; probably taken around September-October of 1942. Don't know where though, maybe Manston? It's pretty clear they were cleared for 100 octane by the time the photo was taken though

I have Warner's Blenheim book and in reviewing the bit about 100 octane in the outer wing tanks he wrote:

"To take full advantage of 100 octane petrol the supercharger pressure could be increased from the normal 'Plus 5 lb/sq.in. boost' by the operation of an 'Emergency Boost Override' lever on the instrument panel. This overrode the Automatic Boost Control to allow 'Plus 9 lb' pressure, and was used for take-off and in emergencies only, for a maximum of 5 minutes."

Interesting - and not unlike the Hurricane and Spitfire use of the boost cut-out enabling +12 lbs, although rather more complicated in practice apparently.

[Blackdog_kt]

I did some research on this when i was active on my pet project, "getting off the ground in a Blenheim in CoD"

After reading through a copy of the pilot's operating handbook i found online, that's what i could gather:

1) Extra tanks were installed in the wings for more range.

2) This made the aircraft too heavy to safely take-off with bombs loaded.

3) Higher boost was needed.

4) Only the outer tanks got 100 octane fuel to assist in take-off, enabling use of +9 psi boost.

This can be easily gleaned from reading the checklists. It was not as much of a WEP setting, as it was simply a "take off when overloaded" power setting.

There were also other kinds of weirdness involved because only one pair of tanks had the ability to jettison fuel, the default inner tanks.

This meant that the potential for WEP was completely wasted: crews were instructed to cruise to the target on the outer 100-octance tanks and drain them completely before switching to the inner ones, since the outer ones couldn't be drained by jettisoning fuel in an emergency.
As such, the 100 octane fuel was effectively used during the probably safest part of the journey at cruise settings (or at least when some element of surprise still existed, during the inbound leg), not during the return from the target for escaping flak and fighters when it would mostly be needed.

Historical loadouts for short range missions were what we use when we fly it in multiplayer on the CoD map: just 55%-60% of fuel (that is the threshold between inner and outer tanks), with the engines limited at +5 psi boost.

[NZtyphoon]

Originally Posted by lane

Thanks for the info from Bingham's book. I don't know much about the Whirlwind, so I'm going to see if I can find a used copy. I appreciate the tip. I too figured the photo of the Whirlwind and bowser to be a 137 Squadron Whirlwind; probably taken around September-October of 1942. Don't know where though, maybe Manston? It's pretty clear they were cleared for 100 octane by the time the photo was taken though

I have Warner's Blenheim book and in reviewing the bit about 100 octane in the outer wing tanks he wrote:

"To take full advantage of 100 octane petrol the supercharger pressure could be increased from the normal 'Plus 5 lb/sq.in. boost' by the operation of an 'Emergency Boost Override' lever on the instrument panel. This overrode the Automatic Boost Control to allow 'Plus 9 lb' pressure, and was used for take-off and in emergencies only, for a maximum of 5 minutes."

Interesting - and not unlike the Hurricane and Spitfire use of the boost cut-out enabling +12 lbs, although rather more complicated in practice apparently.

http://www.amazon.com/Whirlwind-West.../dp/1853100048 ?
The photo is part of a whole sequence of 137 Sqn photos taken at Manston in 1943; the last Whirlwind ops for 137 occurred on 21 June 1943, when 137 stood down to re-equip with Typhoons.The remaining Whirlwinds were transferred to 263 Sqn which had its last op in December before re-equipping with Typhoons.

[lane]

Originally Posted by NZtyphoon

http://www.amazon.com/Whirlwind-West.../dp/1853100048 ?
The photo is part of a whole sequence of 137 Sqn photos taken at Manston in 1943; the last Whirlwind ops for 137 occurred on 21 June 1943, when 137 stood down to re-equip with Typhoons.The remaining Whirlwinds were transferred to 263 Sqn which had its last op in December before re-equipping with Typhoons.

Hi NZtyphoon,

Thanks for the info on the book and the photograph. I’ll get the book. That sure is a nice photo! Unfortunately, I forget where I got it.

Following on the discussion about consumption and the use of 100 octane in the Blenheim, it shouldn’t be overlooked that the Defiant also used 100 octane and +12 boost. See the
Combat Report of T. D. Welsh of 264 Squadron from 29 May 1940 where he recorded "I pulled the boost cut out…" for example.

A.&A.E.E. reported on trials of the Defiant operating +12 boost.


And last but not least see Dowding’s memo from 1st August, 1940, with copies to all Stations and Squadrons, regarding Handling of Merlin in Hurricane, Spitfire and Defiant Aircraft wherein he mentions "The use of the automatic boost cut out control enables the pilot to get an emergency boost of + 12 lbs. per sq.in. from the engine for 5 minutes when circumstances demand it. Some pilots "pull the plug" with little excuse on every occasion."