Its primary role was reciprocating engine pilot training. The compression ratio affects the performance in most types of reciprocating engine. Single-acting cylinders are found in most kinds of reciprocating engine. It excludes turboprop and reciprocating engine powered airliners. The submarine used a compressed-air engine, propelled by stored compressed air powering a reciprocating engine. Powered aircraft typically uses an ICE which may be a reciprocating engine. The mean piston speed is the average speed of the piston in a reciprocating engine. The Miles Master was a tandem-seat low-wing cantilever monoplane, powered by a single reciprocating engine. The torpedo was driven by a small reciprocating engine run by compressed air. Boulton & Watt developed the reciprocating engine into the rotative type. In a reciprocating engine, the cylinder is the space in which a piston travels. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. Watt developed a reciprocating engine in 1769, capable of powering a wheel. Many engine-generators use a reciprocating engine, with fuels mentioned above. In a reciprocating engine aircraft, the throttle control is usually a hand-operated lever or knob.