Guy Norris/LOS ANGELES
Flight tests of the first Boeing Business Jet (BBJ) equipped with winglets began on 20 February at Mesa, Arizona. The tests are aimed at evaluating the structural loads created by the original 2.4m (8ft)-tall blended winglet and a shorter version which will be tested at the end of the current phase. The company is also looking at a series of other performance improvements.
The trials, which finish in late March, will determine the extent of structural reinforcement needed for the outboard upper wing surface. The data will be used for the design of production BBJ wings from 2000 onwards, as well as to develop retrofit kits for aircraft either already delivered, infitting out or in production. The strengthening is needed to counter the torsional forces generated by the flow field around the winglet.
The retrofit kit would also be flight-tested around July, says Boeing, which hopes to be awarded a US Federal Aviation Administration (FAA) supplemental type certificate (STC) in November. The STC would be obtained and held by Aviation Partners of Seattle, Washington, the company which designed and originally developed the blended winglet concept.
Boeing believes the winglet will result in a 550km (300nm) range increase, or alternatively result in 5% lower fuel burn. This overall performance benefit also includes the impact of the anticipated 230kg (500lb) weight penalty, though this weight could be reduced pending the outcome of tests on the smaller winglet, says Boeing.
Further performance improvements such as a speed increase and higher cruising altitude are also "in the budget" to be studied, says Boeing. "The biggest bang for the buck is the winglet and that's where we are focusing our research efforts now. However we do have budget set aside this year to study raising the cruise altitude above 41,000ft and cruise speed beyond 0.82 Mach. Studies on these prospective improvements are not due to begin until mid-year at the earliest," says the company.
Boeing now plans to send a cabin mock-up to the Paris air show this year instead of the first production BBJ, which is scheduled for delivery to General Electric in July. Boeing Netjets, the fractional ownership venture between the manufacturer and Executive Jet, is currently conducting a nationwide tour of the USA with the mock-up. It plans to take delivery of its first aircraft in January 2000, plus a further six later that year.
The company plans to take the remaining 19 aircraft it has on order at the rate of around five per year, says Executive Jet senior vice president Kevin Russell. "We've committed to nine aircraft with 16 options, but we would not do a programme for just nine".
Source: Flight International
