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

[NZtyphoon]

100 Octane Fuel Consumed

July - Aug 1940 = 20,000 tons consumed
Sept - = 14,000 tons consumed
Oct = 17,000 tons consumed
Total = 51,000 tons of 100 octane fuel 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
Blenheim IV = 199 imp gal outer fuel tanks
TOTAL = 470 imp gal divide by 4 = average fighter/bomber fuel load = 117.5 imp gal (Defiant from memory, so feel free to correct me. Defiant II = 104 imp gal)

1 ton = 315.5 imp gal divided by 117.5 imp gal = 2.6 fuel loads (or sorties) per ton of 100 octane fuel.

*This is 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.

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

July to August: 20,000 tons x 2.6 = 52,000 sorties
September: 14,000 tons x 2.6 = 36,400 sorties
October: 17,000 tons x 3.5 = 44,200 sorties
Total July-October 132,600 fuel loads consumed or 132,600 sorties in which all aircraft landed with empty tanks.


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.

Hooton’s Eagle in Flames, Table 2, FC flew Sep 23-29: 4,825 defensive sorties Sep 30 – Oct 6: 1,782 defensive sorties.

Total = 57,971 sorties yet

In spite of Blenheims being mixed in there are still 74,629 fuel loads available.

OR

Originally Posted by Kurfürst

And that is just that, about 1/3 to 1/2 the units

were using 100 octane fuel = 19,323 to 28,985 sorties, either that or the aircraft using 100 octane fuel carried out all the sorties, leaving the rest, who were confined to using 87 Octane, to do other things.

Originally Posted by Kurfürst

And that is just that, about 1/3 to 1/2 the units, so quite simply there's no factual basis, or evidence to, that all the others were using 100 octane. It's merely a wishful assumption.

132,600 sorties - 19,323 to 28,985 = 113,277 sorties or 103,615 sorties unaccounted for, including Blenheim sorties Where did all that fuel go?

The only engines cleared to use 100 Octane were the Merlin II III and XII and the Bristol Mercury XV, so it wasn't Bomber Command or Coastal Command who used it all, nor was it Army Co-Operation Command.

[NZtyphoon]

Now, just for interest, this is assuming all Blenheims used 100 octane only (six Blenheim units may have used 100 octane in all tanks)

Blenheim = 479 imp gals
Defiant= 97
Hurricane = 90
Spitfire = 85
Total= 751 imp gals divided by 4 = 187.75

1 ton 100 octane = 315.5 divided by 187.75 = 1.7 fuel loads

20,000 x 1.7 = 34,000 fuel loads
14,000 x 1.7 = 23,800 fuel loads
17,000x1.7 = 28900 fuel loads
Total = 86,700 fuel loads - 57,971 = 28929 fuel loads left over

Even with all Blenheims theoretically using nothing but 100 octane fuel, there was still more than enough 100 octane fuel consumed - not issued - from July through end of October to supply 100% of FC, and some BC, operations. Once again this is also assuming all aircraft landed with empty tanks and had to be completely refueled, rather than being topped up.

But Wait there's More!!

According to Kf (attachment) the only British aircraft to fly during the Battle of Britain were those of Fighter Command and they managed to consume all of the "other grades" of fuel issued, and all of the 100 Octane!?

(Kf also says that consumption of "other grades of fuel went down starting mid to late September. Coincidentally that was the time that Operation Sealion was called off, and the collections of invasion barges that Bomber Command was running intensive operations against dispersed.

http://www.military-history.org/arti...n-timeline.htm

Except, according to the graph, Bomber Command wasn't operating.)

[41Sqn_Banks]

About +12 combat boost for Merlin XII I found a chart posted by Kurfürst which lists that boost. Unfortunately no date is given. National Archives Reference AIR 16/315.

[Crumpp]

The problem here is that you do not know the details behind the paper.

And nobody else does either.....including you.

As for counting "stations" that are supplied with fuel I would remind everyone in this discussion that aircraft can cover considerable distances in short periods of time.

If you want to test a fuel, you need the logistical base to conduct the test. That means stations must have the fuel on hand in the areas your test aircraft are to fly. Otherwise, your maintenance personnel will be draining a lot of fuel tanks for every off station landing.

Aircraft fuel tanks have what is called "usable fuel". There is always some left in the tanks that the lines cannot reach in level flight. The Spitfire POH refers to this as the "effective capacity". That left over fuel can be a significant amount in a WWII fighter. The amount is specific to the individual aircraft and will be found with that airframes weight and balance sheet. The average is about 5 gallons a tank for a WWII fighter.

Next point is "consumed" does not mean it was put in an airplane and used up. Aircraft fuel has a specific shelf life to it. Once mixed it is distributed and considered consumed. For example, 100LL stock is refined only ONCE per year in the United States. The stock is then distributed to the holding yards. When it is dispensed to the airports, the final mix of that stock occurs and it becomes 100LL fuel. Just because the airport buys 15,000 gallons does not mean it will be sold and go into airplanes by the time the shelf life is over. That is why airport managers keep data on fuel sales!

That does not mean they mixed up a huge batches of 100 grade to be "disposed of" either. In many cases fuel can be converted back to stock and then again to a lower grade. It is still 100 grade that is consumed whether it comes back to the holding yard or not!

This is why the same reasoning that was used to "prove" the 100/150 grade extent of use was so flawed. First the strategic stocks must be maintained and once the fuel is mixed, it is "consumed". Nothing to do with it being blown out the exhaust pipe of an airplane.

[NZtyphoon]

Originally Posted by Crumpp

And nobody else does either.....including you.
Aircraft fuel tanks have what is called "usable fuel". There is always some left in the tanks that the lines cannot reach in level flight. The Spitfire POH refers to this as the "effective capacity". That left over fuel can be a significant amount in a WWII fighter. The amount is specific to the individual aircraft and will be found with that airframes weight and balance sheet. The average is about 5 gallons a tank for a WWII fighter.

Next point is "consumed" does not mean it was put in an airplane and used up. Aircraft fuel has a specific shelf life to it. Once mixed it is distributed and considered consumed. For example, 100LL stock is refined only ONCE per year in the United States. The stock is then distributed to the holding yards. When it is dispensed to the airports, the final mix of that stock occurs and it becomes 100LL fuel. Just because the airport buys 15,000 gallons does not mean it will be sold and go into airplanes by the time the shelf life is over. That is why airport managers keep data on fuel sales!

And what does peacetime civil practice have to do with an air force fighting off a concerted air attack over a period of a few months? Absolutely nothing!


For one thing it was standard FC practice to top up the tanks of all of its fighters as soon as possible after every sortie, mainly to avoid condensation traps because of the fuel left in the tanks. Nor did every aircraft land with empty fuel tanks. There was no "shelf life" when it came to running intensive, frontline operations.

No - what this entire discussion comes down to is Barbi's belief that Fighter Command, which proved to be technically astute during the Battle of Britain, deliberately deprived up to half of its front -line pilots of a technical and tactical asset.

People can speculate all they like about "selected units" "certain units" etc because, in the end:

1) Was 100 octane fuel available to Fighter Command? Yes

2) Was there enough 100 octane fuel available to cover all sorties flown by Fighter Command during the battle? Yes

3) Was enough 100 Octane fuel distributed and used throughout the battle to allow Fighter Command to fly all 57,971 sorties from July to end of October? Yes, with more than enough left over to allow Blenheims of Bomber Command to operate.

[Glider]

Crump
I must admit I don't understand what your last posting was about.

As for counting "stations" that are supplied with fuel I would remind everyone in this discussion that aircraft can cover considerable distances in short periods of time
I don't see the connection between the distance a plane can travel and the stations issued with the fuel.

I also don't see the emphasis on testing of the fuel. Testing started in 1938 and was completed in 1939 when it was signed off for use as documented in Kurfursts paper. 1940 is about the use of the fuel in combat, not testing it.

If you wish I can show you the consumption figures, i.e. the fuel used and I can show you the issued figure, which is as you would expect is a little different. That might help clear the topic, just let me know.

Re your comment on the line I posted The problem here is that you do not know the details behind the paper and your reply And nobody else does either.....including you
You are absolutely correct, no one does know the details. No one knows which squadrons, which aircraft, which stations, how it was to be distributed and so on were for the pre war paper. The difference is that I do not pretend to know.
However I do know that this idea of 16 + 2 bomber units wsan't mentioned at all in the Oil Committee meetings who would have been instrumental in the distribution of the fuel to the 16 fighter squadrons whatever those squadrons might be, wherever they may be based.

[Osprey]

You chaps have done your bit. The fact that a couple of sad knobheads still argue the toss even though there is overwhelming evidence is neither here nor there. I feel sorry for their own investigation and journey into history really, because with a viewpoint so precise it is not possible to speculate or deduce anything at all. Past their own lifetimes I dare say everything is debatable and by their own logic it is a large, mostly blank, canvas. I wonder if these guys believe anything at all about WW1, or the Roman Empire, or what happened at the Battle of Trafalgar, or anything where there is nothing to absolutely state in triplicate with recorded footage about that something happened in the past. Cpt. Mainwaring has the perfect response to them imo.....