Dickerson explained that G280 is the only aircraft in this class to have both full-authority auto throttles and an auto-braking system. It is also the only super midsize aircraft in current production to offer an optional head-up display and an enhanced vision system, although these were not installed on the demonstrator.
Dickerson and Wilson prepped the aircraft and they had the APU running when we arrived at Gulfstream's ramp at its Dallas-Love Field facility (elev. 487 ft.). Outside, the temperature was 33C/91F; inside the aircraft it was 70F.
Pre-start checks were straightforward, using the standby multifunction controller to run through stall warning, TCAS and TAWS tests, plus setting the landing field elevation. The FMS performance database was not yet certified, so Wilson computed takeoff data for a 32,000-lb. takeoff weight and flaps 20 deg. He calculated 106 KIAS for V1 takeoff decision speed, 112 KIAS for rotation and 124 KIAS for the V2 OEI (one-engine-inoperative) takeoff safety speed. En route climb speed was 171 KIAS. Using those speeds and opting for a “bleeds off” takeoff, we computed takeoff field distance at 3,725 ft.
Rolling out of the chocks, we found the nosewheel steering and new brake-by-wire system to be smooth and precise.
Once cleared for takeoff on Runway 13R, we advanced the throttles midway and engaged the auto-throttle system. Rpm advanced to 90.6% N1, providing just under 7,400 lb. of thrust on each engine. With a weight-to-thrust ratio of 2.16:1, acceleration was spirited.
Rotation force was moderate and roll force was well harmonized with pitch force. The ailerons and elevator have virtually no perceptible on-center stiction, making the aircraft quite enjoyable to hand fly. In addition, thrust changes cause very little pitch change. Some pilots may not want to relinquish control to the autopilot, but the auto-throttle system is so smooth and precise that there is little reason not to use it.
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.