Consumption test

**CZ_RAF** · 21st January 2021, 22:05

Hi all,

I am interested if RAF had a prescriptions how to make a Consumption test during WWII? I suppose it may differ for single engine, twin engine and four egine aircraft?
Anyone can suggest me any good source to study this theme? My ggogling so far did not bring anything.

TIA

Pavel

**JDCAVE** · 24th January 2021, 04:25

Pavel: AIR 14/3939, Report on investigation into petrol and bombloads. 3 February, 1944.They recommended the calculations be based on “operational track miles per gallon” rather than air miles per gallon or track miles per gallon.

I have not seen this report, but I found it referenced in “The Science of Bombing“ by Randall T Wakelam. See Pages 164-168.

Jim

**CZ_RAF** · 24th January 2021, 11:37

Jim thank you very much, sounds interesting!
I would never check it as it is named "Bomb loads: planning".
I have added it to my long list hwen TNA will open again.

Pavel

**JDCAVE** · 24th January 2021, 16:59

Pages 166-167, “...the actual miles flown per gallon dropped off from 1.0 to as little as 0.78 for the Halifax III.” For safety allowance they added another 200 gallons to cover for losses from enemy action, getting lost, poor engine management etc.

I have petrol loads carried for 6-Group Lancasters in March 1945 as well as bomb loads, as these are recorded in the “Form B’s”. I also have estimated the track miles for the raids in March that dad flew. I have not looked at this in further detail.

Jim

**JDCAVE** · 24th January 2021, 18:14

Pavel: I had already did some calculation here and it seems that the figure "200 spare gallons" was exceeded by 6-Group lancasters in March 1945. I've sent you a PDF of my calculations but for Ruhr Targets (Cologne, Essen and Mathias Stinnes) I estimate just over 400 gallons of surplus fuel based on 1 air track mile per gallon, and for Chemnitz and Dessau, a surplus of 275 gallons.

Jim

**CZ_RAF** · 25th January 2021, 06:22

Thank you Jim, I will check them.

Pavel

**JDCAVE** · 26th January 2021, 05:50

Edit: I have rewritten this post. It was poorly written, not clear and I apologize.

Pavel: I have looked at this a bit more carefully:

As alluded to in an earlier post, Wakelam writes that “existing Command figures did not take into account a number of operational considerations such as diversions, landing congestion, extra consumption over heavily defended targets and strong winds. Therefore, the ORS recommended that “the calculations be based on “operational track miles per gallon” rather than air miles per gallon or track miles per gallon. No formula was proposed for these calculations, rather the ORS should continue to monitor what Groups were actually doing. The ORS did recommend that a standard safety reserve of 200 gallons should be used across the command (300 gallons for Stirling A/C).

I found some information on what 6-Group had determined in February, 1945:
https://heritage.canadiana.ca/view/o...0/1042?r=0&s=3

6-Group expressed fuel consumption in “Gallons per hour” and summarized this statistic by squadron and aircraft type:

Halifaxes:
429-220 Gallons/hour (GPH)
427-226
408-224
426-232
420-223
425-231
415-233
432-238
Average: 228

Lancasters:
428-194 Gallons/hour (GPH)
419-198
431-181
434-185
424-190
433-184
Average: 189

Note that 428 and 419 were the first squadrons assigned the Mark X aircraft and were using older aircraft than 431, 434, 424 and 433 squadrons. Dad indicated that the aircraft he used in February 1945, KB.721 (to Dresden Feb 13, 1945 “all engines gave trouble”) and KB.738 (to Duisburg, Feb 21, 1945 “Bags of engine trouble) were horrible a/c. and fuel efficiency may have suffered as a result.

I have the Form “B’s” for March 1945, which indicate the petrol loads to be carried in gallons as well as bomb-loads. I calculated the estimated fuel used for the following operations in March:

March 1, 1945, Manheim. Logbook records 7.25 hours, multiplied by 419 Squadron average fuel consumption per hour of 198 = an estimated 1,436 gallons used on the flight. The form B specified a petrol load of 1780 gallons. 1780 minus 1,436 =345 gallons remaining on landing. Track Miles for the route to Manheim, 1,383 miles. “Air Track Miles per Gallon” = 1,383/1,436= 0.96

Following the same calculations for Cologne, March 2, 1945. 6.25 hours, fuel consumption 1,238 gallons. Petrol load 1,550, 313 gallons remaining. 1,131 Track Miles/1,238 gallons = 0.91 Air Track Miles per gallon.

Chemnitz, March 5, 1945. 10.25 hours, fuel consumption 2,030 gallons. Petrol load 2,154, 125 gallons remaining. 1,844 Track Miles/2,030 gallons = 0.91 Air Track Miles per gallon.

Dessau, March 7, 1945. 8.83 hours, fuel consumption 1,748 gallons. Petrol load 2,154, 406 gallons remaining. 1,701 Track Miles to the diversion at Odiham/1,748 gallons = 0.97 Air Track Miles per gallon.

Essen, March 11, 1945. 6.58 hours, fuel consumption 1,303 gallons. Petrol load 1,550, 247 gallons remaining. 1,131 Track Miles/1,303 gallons = 0.87 Air Track Miles per gallon.

Mathias Stinnes, March 24, 1945. 6.42 hours, fuel consumption 1,271 gallons. Petrol load 1,500, 229 gallons remaining. 1,113 Track Miles/1,271 gallons = 0.88 Air Track Miles per gallon.

Hannover, March 25, 1945. 6.5 hours, fuel consumption 1,287 gallons. Petrol load 1,450, 163 gallons remaining. 1,250 Track Miles/1,287 gallons = 0.97 Air Track Miles per gallon.

The average “Air Track Miles per Gallon” (as per ORS suggestion) is 0.92.

So that's what I calculate for estimated fuel burned for Lancaster Aircraft per "Air Track Mile"

Jim

**CZ_RAF** · 26th January 2021, 07:01

Jim thank you very much, it seems to me it would take me some time to get in this problematic but I really appreciate you help.

Pavel

**Terry** · 26th January 2021, 07:20

Jim, What is the difference between operational track miles per gallon and track miles per gallon? A fascinating, if somewhat erudite, topic.
Regards, Terry

**JDCAVE** · 26th January 2021, 15:37

Terry: I’m not certain. The calculations I have presented do not account for the miles flown whilst in the circuit before crews set course and in the circuit while waiting to land. Another source of error would be accurately knowing fuel consumed: it could only be determined upon refuelling and only then with the use of a flow meter on the trucks, as tank gauges in the cockpit would be inaccurate and based on my boating experience, possibly biased.

Jim