Ground-launched V-1s were propelled up an inclined launch ramp by an apparatus known as a ("steam generator"), in which steam was generated when hydrogen peroxide (T-Stoff) was mixed with sodium permanganate (Z-Stoff). Designed by Hellmuth Walter Kommanditgesellschaft, the WR 2.3 Schlitzrohrschleuder consisted of a small gas generator trailer, where the T-Stoff and Z-Stoff combined, generating high-pressure steam that was fed into a tube within the launch rail box. A piston in the tube, connected underneath the missile, was propelled forward by the steam. This enabled the missile to become airborne with a strong enough air-flow allowing the pulse-jet engine to operate. The launch rail was 49 m (160 ft) long, consisting of 8 modular sections 6 m long, and a muzzle brake. Production of the Walter catapult began in January 1944.