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

[Al Schlageter]

Originally Posted by Kurfürst

Have you got any luck in the archives, David, you have been a bit silent for a month about the subject.

What have you found?

[Glider]

The only interesting thing that I picked up was that there was a serious shortage of 100 Octane Fuel, serious enough to start impacting operations in the period May to August 1944 (not 1940).
Emergency measures were taken such as switching RAF squadrons which had US radial engines to US 90 octane fuel and a temporary dip below the previously set strategic minimum reserve level. Once the invasion was firm and the pressure eased the situation returned to normal.

There was one file I was after which they couldn't find and another that I had high hopes of, that only had one sheet of paper in it. Its unlikely that I will get to visit again until October.

Kurfurst, How did you get on finding evidence of the May 1940 meetings that support Pips posting?

[Glider]

Originally Posted by Al Schlageter

The following Spitfire and Hurricane squadrons are known to have used 100 octane fuel before or during the BoB:
1, 17, 19, 41, 43, 54, 56, 64, 65, 66, 72, 73, 74, 79, 85, 87, 92, 141, 145, 151, 152, 222, 229, 234, 245, 249, 264, 303, 602, 603, 605, 609, 610, 611, 616

These squadrons were stationed at the following airfields (bold text) at sometime during the BoB.


11 Group

RAF Biggin Hill

- RAF West Malling

RAF Debden

- RAF Martlesham Heath

RAF Hornchurch

- RAF Hawkinge
- RAF Gravesend
- RAF Manston, night fighter base
- RAF Rochford

RAF Kenley

- RAF Croydon

RAF Northolt

RAF North Weald

- RAF Martlesham
- RAF Stapleford

RAF Tangmere

- RAF West Malling
- RAF Ford
- RAF Lee on Solent, RN airfield
- RAF Gosport, RN airfield
- RAF Thorney Island
- RAF Westhampnett


Not sure which Sector airfield these were assigned to but as all the sector airfields had 100 octane fuel, these to would need a stock of 100 octane fuel.

RAF Detling

RAF Eastchurch

RAF Hendon

RAF Lympne


In 10 Group, 5 of the 6 airfields had stocks of 100 octane fuel.

In 12 Group, 7 of the 8 airfields had stocks of 100 octane fuel.

In 13 Group, 7 of the 10 airfields had stocks of 100 octane fuel. Of the 3 that possible didn't have stocks of 100 octane fuel, one was based in the Shetland Is. and the other in the Orkney Is.

I did go to the NA today for a while to do some family history but did spent some time looking at a few of the squadron operational records. Once again I found that the details vary by squadron but can add two maybe three additional squadrons to the list of 100 Octane users.

No 111 squadron (based at Drem)
On the 15th February 1940 the squadron was released while the tanks were drained and replaced by 100 Octane.

No 32 Squadron (based Gravesend)
29th February 1940, 20 new type aircraft fitted with Metal Wings, new propellers and fuel were delivered during the month. 13 L type machines were flown away

No 213 Squadron
24th February new aircraft were delivered to the squadron.

As you can see, no 111 and 32 squadrons are pretty clear, but I have little doubt that no 213 squadron will be debated by some. My personal view is that if 32 squadron received new aircraft with all the improvements, its unlikely that 213 wouldn't less than a week earlier.

I did go to look up 232 squadron but they only formed in July 1940 when 100 Octane was the normal issue, so it wouldn't have been worth mentioning, i did look but there was no mention. I found it interesting that all the dates are in February.

[NZtyphoon]

Okay, how about some simple calculations?

Now, there is no doubt that 100 Octane fuel was available to Fighter Command before and during the Battle of Britain.

How Much? Woods and Dempster say 22,000 tons - which is too low.

http://www.ww2aircraft.net/forum/tec...b-16305-2.html

Mike Williams #26 scroll down to Table II Monthly Consumption of fuel & oil:

June - Aug 1940 = 10,000 tons consumed
Sept - = 14,000 tons consumed
Oct = 17,000 tons consumed

1 imperial gallon of 100 Octane = 7.1 pounds ("Oil" by D.J Peyton-Smith the official British war history on the oil and petroleum industry during WW2 page xvii "Note on Weights and Measures"):

1 ton of 100 octane = 2,240 lbs therefore 2,240 divided by 7.1 = 315.5 imp gal

Fuel Capacities:

Defiant I = 97 imp gal
Hurricane I = 90 imp gal
Spitfire I & II = 84 imp gal
TOTAL = 271 imp gal divide by 3 = average fighter fuel load = 90.3 imp gal (Defiant from memory, so feel free to correct me. Defiant II = 104 imp gal)

1 ton = 315.5 imp gal divided by 90.3 imp gal = 3.5 fuel loads (or sorties) per ton of 100 octane fuel. Assuming all aircraft emptied their tanks for each sortie, and assuming all aircraft shot down = 1 fuel load of 90.3 imp gal

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.

June to August: 10,000 tons x 3.5 = 35,000 fuel loads
September: 14,000 tons x 3.5 = 49,000 fuel loads
October: 17,000 tons x 3.5 = 59,500 fuel loads

June to October = 41,000 tons x 3.5 = 143,500 fuel loads in 22 weeks = 6,523 fuel loads = 931.8 fuel loads per day

If Woods and Dempster 22,000 tons distributed (not consumed) between July and September = 77,000 fuel loads divided by 13 weeks = 5,923 fuel loads per week = 846 fuel loads daily.

The Battle of Britain by T.C.G. James shows 51,364 sorties, day & night from July 10 through Sept 30; some of the most intensive combat took place between these dates. Of course there were quiet periods when far fewer combat sorties were flown by Fighter Command; eg: August 16 & 17, between two days of intensive combat August 15 & 18.

51,364 divided by 13 weeks = 4,280 fuel loads = 611 fuel loads daily
average:

Hooton’s Eagle in Flames, Table 2, FC flew Sep 23-29: 4,825 defensive sorties Sep 30 – Oct 6: 1,782 defensive sorties, and yet consumption of 100 Octane was still increasing.

Been here before, unfortunately http://www.ww2aircraft.net/forum/avi...a-20108-7.html

[TomcatViP]

Originally Posted by NZtyphoon

Now, there is no doubt that 100 Octane fuel was available to Fighter Command before and during the Battle of Britain.

really ?

20000 post of the same "piece of evidence" does not makes it a demonstrated fact. We are still waiting for some cross references.

[41Sqn_Banks]

Originally Posted by TomcatViP

really ?

20000 post of the same "piece of evidence" does not makes it a demonstrated fact. We are still waiting for some cross references.

One combat report that shows the use of +12 boost (which requires 100 octane) is enough to proof that 100 octane was available. Of course it doesn't proof that it is available to all units, that's why NZtyphoon did the calculation.

[lane]

Originally Posted by 41Sqn_Banks

One combat report that shows the use of +12 boost (which requires 100 octane) is enough to proof that 100 octane was available.

Here's one!

[lane]

June - Aug 1940 = 10,000 tons consumed
Sept - = 14,000 tons consumed
Oct = 17,000 tons consumed

Hi NZtyphoon:

Please note that the 10,000 tons of 100 octane, shown in Table II - Consumption consumed for the period June - Aug 1940, is the monthly average of those 3 months, therefore for the period June - Aug 1940 30,000 tons were actually consumed.

[VO101_Tom]

Originally Posted by lane

Here's one!
http://www.spitfireperformance.com/lane-26-5-40.jpg

IIRC no one contested this (availabe or not), only the quantity.
Interesting report. When he used the 12 lbs boost on deck, he was able to fly with only 300 mph...

[Kurfürst]

Originally Posted by VO101_Tom

IIRC no one contested this (availabe or not), only the quantity.

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.

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. As another poster said, its a bit boring to see the same piece of non-evidence posted the 20000th time, it only seems to reinforce the sense that some people are perhaps a bit fanatical about enforcing their views on the others.

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).

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.

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.

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).

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.

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.