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Query on 'Fuel Tanks Used' in the simulation variables

DragonflightDesign

DragonflightDesign

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For example : RECIP ENG FUEL TANKS USED:index where index is a mask for fuel tanks used. I interpret this as possibly meaning that the bit flags will indicate all tanks that have been connected to the indexed engine at some time (not necessarily now - that would be RECIP ENG FUEL TANK SELECTOR:index. Can anyone confirm my guess i.e. if engine 1 had center and left tip tanks connected at some point then the bitfield would be 0000010001? Or does it get returned as a decimal? (please no!) so the response would be 17?
 
So, in the absence of a response I ran up some code to check 🤪:

1. RECIP ENG FUEL TANK SELECTOR:index gives meaningful data if only a single enumerated fuel tank (including 'all') is connected to that selector at any given time - see 'Fuel Tank List' in the SDK
2. RECIP ENG FUEL TANKS USED:index is used when more than one fuel tank can be attached to the selector at any given time- see the bitmask under 'Aircraft Engine Variables' in the SDK
3. Yes. The answer is returned as a decimal figure indicating the mask bits in use

For the Cessna 172 (two tanks, one selector) we get the following as we switch left -> both -> right:

RECIP ENG FUEL TANK SELECTOR:1 indicates 2 (left), 1 (all), 3 (right)
RECIP ENG FUEL TANKS USED:1 indicates 8 (bit 3, left), 72 (bit 3 and bit 6, left and right), 64 (bit 6, right)

Of the two, RECIP ENG FUEL TANKS USED:X is the best one to give you a complete picture of the fuel tanks connected to a selector.

Edited for clarity.
 
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