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Hello all,
The fuel system of the 747 classic is quite complicated. I have devised my own fuel flow formula that works exactly according to the charts I have for the Boeing 747 from a JT9D maintenance manual. The hard part is now making the fuel system work from the correct tanks.
I have a good understanding of DD's Fuel Dump gauge, and I have verified a couple of configurations. I successfully have the tip reserve tanks emptying into the mains correctly, as an example. However, I am really wracking my brain for a simpler way to write this, without using dozens of if els statements if possible.
Here's how the system works:
There are 7 tanks on the 747, from left to right looking forward:
Tip Reserve 1
Main 1
Main 2
Center Wing
Main 3
Main 4
Tip Reserve 4
Tip tanks do not directly feed engines. They can only be emptied into their adjacent main tank (1 or 4). Any main tank can be used to feed its respective engine. The center tank can feed all engines provided the crossfeeds are open and their respect pumps are off. If any main tank pump is on, the corresponding engine will feed from that tank no exceptions. If any tank has both pumps active, there is enough fuel pressure to power 3 engines, but not all 4 from a single tanks pumps.
Any ideas? If it has to be long and complex I will do it - but I'd like to save the effort if there's a potentially easier way.
Thanks!
The fuel system of the 747 classic is quite complicated. I have devised my own fuel flow formula that works exactly according to the charts I have for the Boeing 747 from a JT9D maintenance manual. The hard part is now making the fuel system work from the correct tanks.
I have a good understanding of DD's Fuel Dump gauge, and I have verified a couple of configurations. I successfully have the tip reserve tanks emptying into the mains correctly, as an example. However, I am really wracking my brain for a simpler way to write this, without using dozens of if els statements if possible.
Here's how the system works:
There are 7 tanks on the 747, from left to right looking forward:
Tip Reserve 1
Main 1
Main 2
Center Wing
Main 3
Main 4
Tip Reserve 4
Tip tanks do not directly feed engines. They can only be emptied into their adjacent main tank (1 or 4). Any main tank can be used to feed its respective engine. The center tank can feed all engines provided the crossfeeds are open and their respect pumps are off. If any main tank pump is on, the corresponding engine will feed from that tank no exceptions. If any tank has both pumps active, there is enough fuel pressure to power 3 engines, but not all 4 from a single tanks pumps.
Any ideas? If it has to be long and complex I will do it - but I'd like to save the effort if there's a potentially easier way.
Thanks!