The Duchess is an all-metal low-wing monoplane with retractable
tricycle landing gear and a
T-tail. It seats four. The design used components and the bonded wing construction from
Beechcraft's single-engined
Musketeer line. The basic fuselage and wing structure was adapted from the Model 24 Sierra, a Musketeer variant with
retractable landing gear, but the Sierra
wing spar was redesigned to support the added weight of the engines. Nose landing gear from the
A36 Bonanza was used. In 1979, a single example was converted to test the turbocharged versions of the engine. The cowlings were reshaped and the exhaust moved to accommodate the aft-mounted turbochargers.
AVweb wrote that Beechcraft adopted the T-tail after flight tests revealed that the initially used conventional horizontal stabilizer was too small and suffered from buffeting problems, increasing noise and vibration during flight; moving the horizontal stabilizer out of the propeller slipstream eliminated the buffeting and the need for enlargement while adding only of weight. Additionally, the T-tail design moved the stabilizer rearward, increasing its effectiveness and giving the aircraft a broader
center of gravity range. The later
Piper Seminole also adopted a T-tail. ==Variants==