Thorp T-18: A High-Performance Homebuilt Legend
The Thorp T-18, designed by John Thorp in 1963, is an iconic two-place, all-metal, plans-built homebuilt aircraft renowned for its speed, simplicity, and innovative design. With over 1,600 sets of plans sold and approximately 400 aircraft flying by 2011, the T-18 became a favorite among aviation enthusiasts for its performance and affordability. Our museum proudly displays a T-18, showcasing its engineering and the legacy of this remarkable homebuilt aircraft.
History
The Thorp T-18 emerged during the 1960s homebuilt aircraft boom, designed by John Thorp, a prolific engineer who contributed to the Piper Cherokee and held a patent for the stabilator (all-flying tail). Initially conceived as an open-cockpit aircraft powered by a surplus Lycoming O-290G engine, the T-18 evolved into a bubble-canopied, high-performance machine with engines up to 200 hp, such as the Lycoming O-360. Its all-metal construction, using twelve 4′ x 12′ aluminum sheets, made it accessible for amateur builders, with ribs and frames hand-formed over plywood blocks. The T-18 gained fame for historic flights, including the first homebuilt circumnavigation of the world in 1976 by Don Taylor in N455DT, which also flew to the geographic and magnetic North Poles. By the 1970s and 1980s, the T-18 was a leading homebuilt design, though its popularity later waned with the rise of Van’s RV series.
Design Features
The T-18 is a low-wing, two-seat, side-by-side monoplane with a sleek, all-metal airframe. Its design prioritizes simplicity and performance, using aluminum sheets (0.016 to 0.040 inches thick) for the fuselage and wings, and 4130 steel tubing for the landing gear “A” frame, heat-treated to 180,000 lbs./sq. in. The aircraft features a sliding bubble canopy, resembling a fighter jet, and a stabilator, which Thorp pioneered for enhanced pitch control and reduced tail weight. The landing gear, bolted to the firewall, absorbs stresses independently of the fuselage, ensuring durability. Engine options range from the 125 hp Lycoming O-290 to the 180 hp O-360, with many T-18s incorporating upgrades like the wide-body “C” wing modification for improved handling.
Specifications
| Specification | Details |
|---|---|
| Manufacturer | John Thorp (plans-built) |
| Model | T-18 (or S-18 variant) |
| First Flight | 1963 |
| Crew | 2 (side-by-side) |
| Wingspan | 20 ft 10 in (6.35 m) |
| Length | 18 ft 2 in (5.54 m) |
| Height | 5 ft 1 in (1.55 m) |
| Empty Weight | 900 lb (408 kg) |
| Max Takeoff Weight | 1,500–1,900 lb (680–862 kg, depending on configuration) |
| Powerplant | Lycoming O-290 (125 hp) to O-360 (180 hp) |
| Fuel Capacity | 29 gal (110 L, usable) |
| Max Speed | 200 mph (322 km/h) |
| Cruise Speed | 160–180 mph (257–290 km/h) |
| Stall Speed | 65 mph (105 km/h) |
| Range | 500–850 nm (926–1,574 km, depending on configuration) |
| Service Ceiling | 18,000–20,000 ft (5,486–6,096 m) |
| Rate of Climb | 1,500–2,000 ft/min (7.6–10.2 m/s) |
Flight Characteristics
The T-18 is celebrated for its responsive handling and high performance. With a 125 hp engine, it cruises at 160 mph (257 km/h), while 180 hp versions exceed 200 mph (322 km/h). Its stabilator provides light, harmonized control forces, making it agile in flight. The aircraft’s small wing (NACA 63A-412 airfoil) and low weight enable a 1,500 ft/min climb rate and short takeoff runs (300–1,000 ft). However, its short-coupled taildragger design and high landing speed (around 65 mph) demand skilled piloting, especially on landing, which requires 1,800 ft at gross weight. The T-18 is aerobatic, rated for +6/-3 G at 1,250 lb (standard wing) or 1,500 lb (“C” wing), though advanced maneuvers risk exceeding VNE (never-exceed speed). The T-18 balances speed, economy (9 gal/hr at cruise), and agility, making it a favorite for recreational pilots.
Museum Significance
Our museum’s T-18 exemplifies the legacy of this pioneering homebuilt aircraft. Its presence highlights the ingenuity of John Thorp and the dedication of amateur builders who brought these plans to life. The T-18’s historical achievements, such as its world-circling flight and polar expeditions, underscore its engineering excellence. The aircraft’s all-metal construction, fighter-like canopy, and stabilator are showcased, inviting visitors to explore its role in advancing homebuilt aviation and its impact on recreational flying.