The RW4 airframe is constructed entirely from wood and covered with aircraft fabric. The landing gear is of conventional configuration with bungee suspension. As on the original Church design the RW4 has a gap between the wing and fuselage to allow the pilot to see downwards. The aircraft's installed power range is 20 to 48 hp (15 to 36 kW) and the standard engine was originally the 30 hp (22 kW) Kawasaki 340. The 35 hp (26 kW) Half VWfour-stroke engine, 28 hp (21 kW) Rotax 277two-stroke and 28 hp (21 kW) 2si 430 two-stroke have also been used.[1][2][3]
Partial kits and construction kits were available in the late 1990s, but today the aircraft is offered only in the form of plans. Reported construction time is 400–600 hours, although the designer claims 350 hours.[1][2][4][5]