The Beagle B.121 Pup is a 1960s British 2–4 seat single-engined training and touring aircraft built by Beagle Aircraft Limited at Shoreham Airport and Rearsby Aerodrome. Design The Pup was designed as a single-engined all-metal two-seat aerobatic aircraft or a four-seat touring aircraft. The Pup was more spacious than its direct competitors and was more of a "pilot's aeroplane"; it was a more complex design to manufacture and was also corrosion proofed throughout (usually then only an option on US-built competitors). For these reasons it was correspondingly more expensive to build, yet was sold at a competitive price. Beagle Aircraft Ltd chose to build the Pup following a market survey which demonstrated a global requirement for a modern, all-metal 2–4 seat training/touring aircraft to replace aging Tiger Moths and Pipers used by flying clubs. American manufacturers were already fulfilling this demand with aircraft such as the Cessna 150, 172 and the Piper Cherokee. Development The prototype Pup (a Series 1 G-AVDF) first flew from Shoreham Airport on 8 April 1967. The second prototype, the first more powerful Pup 150 (G-AVLM) with seating for an extra adult, was first flown on 4 October 1967, followed by the third prototype, another Series 2 (G-AVLN), on 17 January 1968. The Series 2 aircraft were fitted with an enlarged rudder which became standard on all production aircraft. G-AVLM was converted during 1968 to become the Series 3 prototype aircraft with a further enlarged rudder. Because these aircraft types were identical from behind the engine firewall (as commonality reduces costs), the Series 1 was heavier than it needed to be. This penalized its performance which was described as less than "sporty". Another issue affecting the Pup was unreliability, due to both poor design and workmanship, and the shortage of spare parts. These problems included fuel leaks, cockpit door failures and brake and undercarriage issues. However, the main issue as the Pup developed was the cost of production. Flight magazine, commenting on the uneconomic construction, said that the Pup "appears to be designed not for production but as a one-off special in which cost was no object". Beagle had planned to achieve a basic manhour figure of 780 hours per aircraft by the 250th aircraft, but they were well behind the learning curve to achieve this. It was estimated in November 1969 that the production cost per aircraft for the first 150 was £8,850, over double