The envelope is fabricated from polyester cloth, coated inside with saran film for gas retention and outside with polyurethane loaded with titanium dioxide for durability. The gondola is a kevlar-reinforced moulding, suspended from the top of the envelope by kevlar cables. The pilot controls elevators and rudders on the tail surfaces by fore-aft and lateral movement of a yoke, via a manual, cable-operated system. In response to Airship Industries intent to enter the military market, Marconi did start on a system using fibre optics to carry the control signals to electrical actuators. This could reduce pilot workload, make control response more precise but be resistant to electrical interference.