do you happen to know if the Hydrierwerke Scholven A.G. plant at Scholven Buer was operational in late December, 1944? I have a reference that indicates it may not have been serviceable. Dad was part of the force that bombed it December 29, 1944.
I agree the oil was not part of the empty weight. Using the weights breakdown in Avro Lancaster by Harry Holmes,
weight of structure + power plants + fuel and oil tanks = empty weight,
empty weight + fixed military load = tare weight,
tare weight + crew + removable military load + fuel and oil + bombs + carriers = gross weight.
The Bomber Command Official History reproduces (some of) Speer's fuel reports to Hitler, like in AIR 8/1019. While the RAF Air Historical Branch did translations of German Air Raid Damage Reports. I cannot answer the question about whether the plant was in service attacked on 29/30 December 1944, the following is more about noting the different names being used and what sort of German reports may be available. Year is 1944.
GELSENKIRCHEN E.2700 - Lw. Ops. Staff, E.2606 - Min. of Arm. & War Prod, 12/13 JUNE, 14/15 JUNE. During the night of 12/13 June an attack was made on the Gelsenberg aviation fuel plant (in Gelsenkirchen / Horst) which, in view of the level of its production, is second in importance to Poelitz. All the vital parts of the plant were heavily damaged and there will be no production for at least three months.
During the night of 14/15 June an attack was made on the plant at Scholven (in Gelsenkirchen-Baur), which is in fifth place on the production scale (directly after Leuna). Production was halted temporarily at the plant which sustained comparatively slight damage but will be resumed in a few days. The monthly loss of production amounts to 35,000 tons or 17% of production for the whole of Germany, bringing the total loss for Germany to 140,000 tons a month or 73%. Gelsenberg will not be ready for production again for several months.
In addition Document E.2606 gives details of raids on the Scholven Hydrogenation Plant, of which the following were the heaviest;
| Date | Time | A/C. | H.E. | On Works |
| 22. 6. | 0142 - 1157 | 200 | 800 | 33 |
| 19. 7. | 0126 - 1040 | 350 | 2000 | 550 |
| 26. 8. | 1218 - 1231 | 80 | 600 | 400 |
| 12. 9. | 1328 - 1405 | 500 | 2500 | 350 |
| 6. 10. | 1657 - 1706 | 100 | 500 | 200 |
| 1. 11. | 1354 - 1402 | 200 | 1500 | 200 |
| 11.11. | 1120 - 1128 | 150 | 800 | 40 |
| Total: | All | 1580 | 8700 | 1773 |
It is also reported that 291,433 sq. metres of floor space were destroyed. An 8 March 1945 raid report says the hydrogenation works in Scholven and the Gelsenberg-Benzin A.G. were hit.