Ground Operations, Taxi and Takeoff
Planes don't just magically show up at the end of runways ready to go. They must be inspected, forms reviewed, started, systems checked, routes verified, and weapon's profiles and programing verified.
Recall, our conventional 20 x JASSM configuration.
OEW - 185,000 pounds
12 Ext JASSM - 49,400 pounds
8 Int JASSM - 24,800 pounds
Weight before fuel - 259,200 pounds
Fuel for Max Gross Weight - 228,800 pounds
Gross Weight - 488,000 pounds
Typically, with bombers you step 60-90 minutes prior to takeoff and start engines 45-60 minutes prior to takeoff. Combat missions would follow the longer timeline. So, 60 minutes of 65% thrust setting is a good stand in for idle thrust with some elevated settings for starts and checks. The chart gives us a fuel burn of 103 pounds per minute which gives us 6,200 pounds for ground operations and taxi (60 x 103 = 6,180). Yes, the jet burns three tons of fuel an hour sitting at idle. Throw in an extra 1,000 pound for taxi.
So, an initial fuel load of 236,000 pounds yields a ramp weight of 495,200 pounds which is safely below the max ramp weight of 500,000 pounds.
Ground operations and taxi burned 7,200 pounds and puts us on the runway with exactly a 488,000-pound max gross weight takeoff. Barksdale is essentially a flat runway (two-foot difference between the ends). The second chart yields a fuel burn from brake release to best climb speed of 3,600 pounds.
Between ground operations, taxi and takeoff we've burned 10,800 pounds of fuel. That's an F-16's worth of internal fuel and two 370-gallon externals. The BUFF starts the climb with 224,200 pounds of fuel for the mission at a gross weight of 484,400 pounds.
Next installment climb.
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Who's up for computing the range and fuel use for the conventional JASSM case?
Global Strike mission originating from Barksdale with a payload of 20 JASSMs. Aircraft will be gross weight at takeoff roll initiation, all conditions for a standard day.
Next installment ground operations, taxi, and takeoff.