The Mathews PUP (Perfect Ultralight Plane), also called the P.U.P., is an American ultralight aircraft that was designed by Lyle Mathews in 1983 and made available in the form of plans for amateur construction. Design and development The aircraft was designed to comply with the US FAR 103 Ultralight Vehicles rules, including the category's maximum empty weight of . The aircraft has a standard empty weight of . It features a biplane wing arrangement, a single-seat, open cockpit, conventional landing gear and a single engine in tractor configuration. The aircraft is made from aluminum tubing and covered in Dacron sailcloth. Its span, unstaggered wings employ both interplane struts and cable bracing. The lower wing has less span than the upper wing. The fuselage consists of a single aluminum rectangular 2x3 inch (5 X 8 cm) tube. The standard recommended engine is a Kawasaki 440 snowmobile engine that produces and yields a cruise speed along with a rate of climb of 600 feet per minute (3.0 m/s). Specifications (PUP) References External links Photo of a PUP PUP 1980s United States ultralight aircraft Homebuilt aircraft Single-engined tractor aircraft