Envelope protection means that, for example, no matter how hard a pilot pulls back on the yoke the computers will not pitch the G650 up to the stalling angle of attack. This protection is achieved in conventional airplanes with a stick pusher that slams the controls forward before the airplane can reach an aerodynamic stall, but the fly-by-wire system will be much more sophisticated and transparent. The computers will also protect the airplane from exceeding its high-speed limits, but in between the extremes, the human pilot will be in charge.
The new certification standards are driving virtually all new jets that are large enough to require hydraulically boosted or powered controls to use fly-by-wire. The level of redundancy required is almost impossible to meet with mechanical systems. For example, the G650 will have dual hydraulic actuators, each fed hydraulic pressure from systems that have at least two sources of power, for each control axis. On top of that are backup hydrostatic actuators that use their own internal electric motors to produce the hydraulic power necessary to move the control surface. Even though there are four independent electrical systems-including a backup ram air turbine generator that pops out into the slipstream in an emergency-on the airplane, there are also dedicated batteries to power the flight control computers and hydrostatic actuators. The system exceeds the already stringent certification requirements for fly-by-wire flight control redundancy.
All other systems on the G650 are being redesigned to take advantage of new technology and to simplify operation and maintenance. For example, a solid-state electrical power distribution system for non-flight-critical items such as lights, cabin systems and so on, saves 300 pounds of weight, eliminates 400 circuit breakers and relays, and removes more than three miles of wire. New brake-by-wire systems maximize braking performance under all runway conditions, while also monitoring both brake temperature and tire pressure. And the fuel system allows the G650 to be fueled to its 44,200-pound capacity in 26 minutes, compared to 45 for the G550. As always in large Gulfstreams, all fuel is carried in the wing where, like the G550, heated fuel is returned so that on those 12- to 14-hour flights in below-standard temperatures the fuel continues to flow.
As with all other large-cabin Gulfstreams since the turboprop G-I, the G650 will be powered by Rolls-Royce engines. The BR725 is a new member of the same engine family used on the G550. The new engine is rated at 16,100 pounds thrust for takeoff, up from 15,385 in the G550. Rolls achieved significant weight savings in the BR725, so its thrust-to-weight ratio is 3.1 percent better and fuel efficiency is 3.5 percent superior. Thanks to a higher bypass ratio and newly designed fan, plus many internal refinements, the new engine is 4 dB quieter, which puts it a full 16 dB below the coming Stage 4 airport noise standard, plus emissions and smoke are reduced by as much as 50 percent.
Almost every other aspect of the G650 will be superior to other Gulfstreams and to other business jets. The company has achieved remarkable gains in cabin sound level in acoustic testing, for example. The baggage compartment is 11 percent larger than in the G550 and is accessible by passengers at any altitude in flight, but the new larger external door is lower to the ramp for easier loading. The newly designed main entry door is the biggest in the business jet fleet with more than six feet of door height. And, of course, the infrared enhanced vision and newly certified synthetic vision systems will be standard in the G650.
First flight of the G650 is scheduled for the second half of 2009, with certification by the FAA and Europeans in 2011 and entry into service expected in 2012. The wing design was frozen in 2006, and a preliminary design review was completed last year. Models have been tested successfully in seven wind tunnels, with two more test regimes scheduled to be completed soon for a total of 1,400 hours in wind tunnels. A conforming fuselage barrel has been built and was successfully tested to beyond certification limit loads for bending and pressurization, including pumping it up to 18.37 psi to validate the new window structure.
Gulfstream expects to fly three test airplanes and two production G650s for a total of 1,800 hours of testing to complete certification. A new factory to assemble the G650 was recently completed, and tooling is already moving into the enormous 308,000-square-foot clear span building. All major component and subassembly suppliers are signed up and have begun work. Gulfstream officials refuse to say how large an investment the G650 requires, but since Cessna estimates it will spend $780 million to build the much smaller Citation Columbus, can at least $1 billion be far off the mark?
The G650 is priced in the "upper $50 million range" in 2012 dollars, which is about $10 million more than the G550 costs today. The G550 will continue in production, and Gulfstream sees no reason to believe that demand for it will diminish. Though Gulfstream talked about the coming G650 to many operators around the world in utmost secrecy, it took no orders or deposits before the official announcement in March. Whoever's deposit check gets there first will be first in line.
It had long been rumored that Gulfstream was working on an all-new model, and most expected it to have a larger cabin, which it does, but the cruise speed and range increases are downright phenomenal. But then, biggest, fastest and longest range is what we have all come to expect from Gulfstream, and the company has not disappointed.