Guy Norris/LOS ANGELES
Raisbeck Engineering is preparing to flight test a specially designed aft fuselage shape for the Gulfstream IV which it hopes will generate drag reductions of up to 6%.
The Seattle-based company, which has already developed a conceptually similar aft fuselage locker for the Learjet, says the shape will function as either a drag reducing fairing, a locker with 680kg (1,500lb) extra baggage capacity, or a long range fuel tank able to hold almost 1,000kg of additional fuel, adding up to 45min of cruise time. Raisbeck says an owner/operator survey is underway to determine interest among the GIV/IVSP fleet. "The results of this survey will be coupled with the flight test results to determine the programme's future direction," it adds.
Raisbeck developed the shape using computational fluid dynamic design techniques in association with Redmond, Washington-based Analytical Methods. A study, funded by Raisbeck and begun last year, is being conducted under a research grant to Purdue University. This is to "culminate in wind tunnel tests of various shapes to determine trade-offs of volume and drag reduction," says Raisbeck.
Flight tests will be carried out on a G IV in the next two months. The shape will be fully instrumented with 96 surface static pressure points to determine airflow and loads. The tests will assess the effect of the shape on drag reduction as well as climb performance to cruise altitude, time to initial cruise altitude, constant power increase in cruise Mach, and cruise fuel consumption reduction.
Additional reporting by Graham Warwick, Washington DC.
Source: Flight International
