McDONNELL DOUGLAS (MDC) plans to begin flight-testing a new aft-nozzle design on its AV-8B Harrier II technology demonstrator, beginning in February. The aircraft has been used to evaluate wingtip-mounted AIM-9 Sidewinders since its first flight on 30 November 1994.
The "zero-scarf" aft nozzles have been developed by Rolls Royce, builder of the Harrier's Pegasus vectored-thrust turbofan. The production AV-8B already has zero-scarf front nozzles, which have exhaust planes perpendicular to the fuselage, rather than angled as in the original design. The new aft nozzles are expected to increase thrust and improve reliability, MDC says.
The AV-8B technology demonstrator, is expected to be flown in March, with revised under-fuselage lift-improvement devices (LIDs). These increase vertical lift by trapping high-energy exhaust gases under the fuselage. Improvements to be tested are a shortened transverse fence and new "mini-strakes" near the nose-wheel doors. The improved LIDS could be fitted to the radar-equipped Harrier II Plus to offset weight increases, MDC says.
MDC also plans to flight-test a ceramic-matrix-composite aft-nozzle blast shield, developed by Northrop Grumman subsidiary Vought Aircraft, on the technology demonstrator in the third quarter of 1995 as a possible replacement for the present titanium blast-shield, which suffers from sonic-fatigue problems.
Source: Flight International
