“We’re on pace,” which is amazing given the pandemic, said Gulfstream’s Collin Miller, senior vice president of innovation, engineering, and flight. Gulfstream’s flight test team—including Miller and Jake Howard, lead test pilot for the G700 program—provided an update on the G700 development program, which is on track, with high-altitude testing complete and flight into known ice (FIKI) testing underway. The team has five test aircraft in the development fleet, and the program has logged more than 1,100 flight hours.
After finishing initial stages of flight test, such as clearing out the flutter envelope, the aircraft have entered specific areas such as cold-weather performance, and high-altitude performance. For the latter, the team took one of the test aircraft to Telluride Airport (KTEX) in Colorado, which sits at a field elevation of 9,038 ft msl—with a 7,111-ft runway. During the programmed expansion of the flight test envelope, the pilots have taken the aircraft to Mach 0.99 and 54,000 ft msl, well beyond the stated normal parameters of Mach 0.94 and 51,000 ft.
“The new engines, the [Rolls-Royce] Pearl 700s on the G700, are performing fantastically well,” said Miller, “and they’re extremely efficient, giving us great results for speed, range, and low emissions.”
Validation of Gulfstream’s efforts to produce a comfortable environment for passengers—and pilots—came with confirmation of the lowest cabin altitude in its class: a 4,850-ft cabin at 51,000 ft. Miller remarked that the test program has been largely one of such confirmations, to which he attributed the success of the company’s significant investment in laboratories able to test extensively system components and performance on the ground prior to the commencement of flight test. “These things just don’t break,” he said of the fleet of test aircraft—often when a test aircraft returns from a flight the pilots hand over a list of squawks to resolve. According to Miller, that has simply not been the case, by and large, with the G700 test fleet thus far.
Much of the wring-out has been with new systems, to determine ideal settings for use operationally by pilots to come. For example, the Predictive Landing Performance System—a runway overrun awareness system—that will go into the G700 takes the energy state of the airplane and the distance available for landing on the runway ahead and alerts the pilots of any discrepancy—based on the aircraft configuration of autobrakes and thrust reversers. The test pilots have helped determine the ideal altitudes for each alert in the series, to avoid nuisance alerts too high on the glide path, yet give enough time for a stabilized go around.
Both Miller and Howard praised these advances in safety in the G700′s Symmetry Flight Deck—including the heads-up display (HUD) available to each pilot, with synthetic vision and enhanced vision on the displays. High-speed protection and low-speed awareness will help pilots stay within the envelope as well.
“Thanks to the outstanding Gulfstream team, the G700 flight-test program is going remarkably well,” said Mark Burns, president of Gulfstream. “The aircraft itself has been performing flawlessly, whether going to extreme speeds and heights or running through its paces in the high-altitude environment at Telluride. We have spent the past year rigorously testing this mature, high-performing aircraft for our customers, and I look forward to continuing to do that and more in the coming months as we steadily move toward certification and customer deliveries.”