After a two-year development effort, Really Quiet has received US certification for its Stage 3 hushkit for Rolls-Royce Spey-powered Gulfstream II, IIB and III business jets. The first modification of a GII is under way at the company's facility in Mojave, California.
The company claims the hushkit reduces noise to a cumulative 6-7dB below Stage 3. Really Quiet has orders for over 50 $1.95 million hushkits, and installations are to begin in April. Really Quiet hopes to retrofit three quarters of the 450 operational GII/IIB/IIIs.
Really Quiet is working on product improvements to reduce the drag and weight penalties associated with the hushkit, which features a translating ejector nozzle. Fitting the hushkit incurs a 5% range reduction and 225kg (500lb) weight increase, but the company believes these can both be reduced by a third.
For take-off and approach, the ejector translates aft to entrain additional air which mixes with the engine exhaust to reduce its velocity and jet noise. The ejector remains partially open in the cruise, allowing some outside air to flow through the nozzle to reduce drag, which will be reduced further in subsequent designs.
Source: Flight International
