After takeoff, the pneumatic system automatically switched from APU bleed air to engine bleed air. At that point, we secured the APU.
Following a 250 KIAS/Mach 0.75 speed schedule, the aircraft climbed westward from Dallas-Love to Flight Level (FL) 450 in 21 min., including a 3-min. ATC delay. That is impressive as the outside air temperatures (OAT) were mostly ISA (international standard atmosphere)+15-17C until we climbed above FL300. At FL450, though, OAT cooled off to ISA-5C. Fuel burn for the climb was about 1,000 lb.
We checked cruise performance at Mach 0.80 normal cruise and Mach 0.84 high-speed cruise at FL450 at ISA-5-6C. At a weight of 30,800 lb., fuel burn was 1,510 lb. per hr. (pph) at normal cruise and 1,810 pph at HSC. The flight manual indicates the aircraft's long-range cruise speed at this weight is Mach 0.79 and fuel flow should be about 1,400 pph. At Mach 0.84, it predicts 1,778 pph at that weight and OAT.
The aircraft was buffet-free up to a 40-deg. angle of bank, corresponding to 1.3g. At maximum takeoff weight, the aircraft has 1.2g of buffet margin from Mach 0.75-0.80 at FL450. Buffet margin drops sharply above normal cruise speed.
We descended to 16,000 ft. for airwork southeast of Abilene, Texas, using idle thrust and the variable position speed brakes for drag. The air brakes produce very mild pitch-up when fully extended and just slight airframe rumble that is unlikely to disturb passengers.
When level at low altitude, we flew a couple of steep turns. It is easy to maintain altitude using the primary flight display's flight path marker and airspeed trend vector. Pitch force is moderately heavy, thereby preventing over control. Roll response, with the help of the fly-by-wire roll spoilers, is crisp, but roll effort is moderate, again preventing over control.
Dickerson next demonstrated the low-speed protection system. If the aircraft is slowed to 72% of the angle of attack (AOA) at which the stall warning stick pusher fires, the auto-throttle system engages and power is advanced to prevent the stall. Up to maximum available thrust, the auto-throttle system will not allow angle of attack to exceed 78% of stick-pusher AOA.
We then flew clean, flaps-20 approach and landing configuration stall approaches to stickpusher at weights of 30,150-30,250 lb. For the three configurations, stall warning stickshaker then stall prevention stickpusher, respectively, were triggered at 139 KIAS and 131 KIAS; 113 KIAS and 106 KIAS; and 107 KIAS and 101 KIAS. Aircraft behavior during each of the maneuvers was very benign.
Next, it was off to Abilene's Runway 35R for pattern work, starting with the instrument landing system approach. Wilson pegged Vref at 128 KIAS for the aircraft's estimated 29,600-lb. landing weight, providing a 23% margin over stall. The auto braking system was set to medium deceleration for demonstration purposes.