Would those be the 600 gallon tanks, or 370 gallon tanks, I'm guessing the larger, which brings us to the why,,,, much of the maneuvering, gear up, gear down during test flying is done at upper low to medium altitude, and likely at lower airspeeds requiring chase to get "draggy" deploying flaps likely even gear, in order to remain in "contact" with the target.. Aircraft are likely flown in to a target airspeed incrementally, it would be instructive if someone that "knew" would include the "test protocol", for instance most airliners are no longer "stalled" but flown in the "stick shaker" and recovered as if they had stalled,,,,, throttle to full, flaps to "takeoff", gear selector "up", etc....Point being that deploying flaps, slats, and landing gear, require higher thrust levels to maintain airspeed and altitude, and hence a much higher than normal fuel burn....
