Graham Warwick/WICHITA
Raytheon Aircraft is to produce the first composite-fuselage section for the Premier I business jet later in November, using fibre-placement technology. The forward-fuselage section is intended as a demonstration article, but could be used in an aircraft if it passes all qualification tests.
A Cincinnati Milacron Viper fibre-placement machine is now operational at Raytheon's Wichita, Kansas factory. The computer-controlled machine automatically places fibre tows on to a fuselage-shaped mandrel with high speed and accuracy, and the company expects to produce a fuselage section in about a day, compared to one to two weeks to fabricate a conventional metal structure.
Raytheon is projecting a substantial reduction in manpower costs and production times for its new fuselage-manufacturing process. Material wastage is expected to be only 5-7%, compared to 57% for the filament-winding process used to produce Beech Starship composite fuselages.
Reduced manufacturing cost is the key to meeting the targeted $3 million price-tag for the Premier I. The fuselage construction also allows increased internal cabin diameter. The first flight, of the Premier I, is due in the third quarter of 1997, followed by certification and first deliveries in late 1998.
The Premier fuselage will be produced in two sections, wound on to mandrels made of cast and rolled steel plates welded together, then machined to the final shape. Raytheon has completed the forward-fuselage mandrel, and expected to finish that for the aft fuselage by the end of October.
A rubber sheath, called the caul sheet, is slipped over the mandrel and the fibre-placement machine then lays down the inner skin of carbon-fibre. The seven-axis machine places up to 24 tows in a band 3-76mm wide, at speeds up to 15ft/min (0.08m/s), stopping and starting tows individually to create apertures for doors and windows.
Honeycomb core and part-cured reinforcements such as door and window frames are then hand-placed on to the mandrel, using a laser-projection system to indicate location. The outer carbon-fibre skin is then laid down automatically. A final layer of lightning-protection fabric is hand-placed.
The mandrel is withdrawn, and the fuselage section enclosed in composite clamshell moulds. The caul sheet becomes a vacuum bag, forcing the fuselage against the moulds during autoclave curing. Initially, completed fuselage sections will be checked for voids using ultrasonic inspection, but a laser-shearography system will be in place by early in 1987.
Source: Flight International
