...rather than having to manually select each tank in order along the way...
I found some interesting information about the sequencing of the P-51D's fuel tanks. The wartime operating notes I looked at suggest that the pilot should take off on the main fuselage tank, then at a suitable altitude to switch to the left main tank for ten minutes to create space for vented fuel vapors. The pilot would then switch back to the fuselage tank until it was drained down to 25 gallons remaining to give the aircraft the best center of gravity. Only then would he start to use the drop tanks or the main wing tanks.
The P-51D/K training manual from 1945 explains that fuel vapor recovered from the carburetor is sent to one of the main tanks:Whenever the engine is running, vaporized fuel is returned from the carburetor to one of the fuel tanks through the vapor return vent line. On later airplanes, this line is led to the fuselage tank, while on some of the earlier P-51D's the vapor return is to the left wing tank. Find out which tank the vapor return line is connected by asking your engineering officer, and use fuel from that tank first to allow space for return. Also, check the tank occasionally in flight to make sure it isn't completely full. If you don't do this, the recovered gas, which may amount to as much as 10 gallons per hour depending on operating conditions, will be lost through the overflow pipe.
The F-51D pilot's training manual from 1954 advises this procedure:Take-off and climb should be accomplished with fuel tank selector handle at Main Tank L.H. because the vapor separation line from the carburetor returns to this tank. Fuel vapors flow from the carburetor to this tank at the rate of approximately one gallon per hour. At altitude, use fuel from fuselage tank until 25 gallons remains, to have ideal CG condition for landing. Then cruise on drop tanks alternately until they are empty. Continue flight using main wing tanks alternately, to prevent wing heaviness, until they are empty. Then use fuel from fuselage tank during landing.
Warning --The fuel booster switch must be ON during flight to ensure an adequate fuel supply.
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