Possible change of direction away from transonic option to Super Efficient does not mean end of concept

Boeing is offering airlines a choice between one of three Sonic Cruiser concepts and a "Super Efficient" conventional design amid signs that operators are pushing for the latter to enter service around 2008.

Based on current talks with around 20 potential airline customers, Boeing expects to make a final decision by January and get company board approval for authority to offer by the end of next year. Although declining to "indicate a leaning", Boeing now appears for the first time to be reinforcing earlier signs of a change in direction for its next generation transport away from Sonic Cruiser towards the conventional design, formerly dubbed Project Yellow-stone. The change is believed to have been confirmed at a Sonic Cruiser airline meeting in Seattle in late October at which none of the potential operators gave a high rating to the faster aircraft's proposed Mach 0.96-0.98 cruise speed.

Sonic Cruiser vice-president and general manager Walt Gillette says a Super Efficient choice does not mean the end of the fast-jet concept. "If we decide to do a Super Efficient aircraft first it does not rule out a Sonic Cruiser," he says. Although Boeing "is not really thinking about launching two aircraft simultaneously", the advanced processes being studied for the next step "will allow us to do two fairly quickly", he says. Gillette also confirms two of the three final Sonic Cruiser designs are capable of supersonic speeds beyond M2, raising speculation that Boeing could be considering the development of a Supersonic Cruiser later this decade as a family adjunct to the Super Efficient and possibly nearer-term Sonic Cruiser.

Baseline design goal for all the options is a 757/767-size aircraft with 200-250 seats, but with a 13,880km (7,500nm) range. "The airline's choice is either to go 15 to 20% faster at M0.96-0.98, or to fly at today's speed and altitude but burn quite a bit less fuel," says Gillette. The Super Efficient option burns around 10% less fuel than the Sonic Cruiser and 17-20% less per passenger than a 767-300.

Source: Flight International