The Piper PA-30 Twin Comanche is an American twin-engined cabin monoplane designed and built by Piper Aircraft. It was twin-engine development of the PA-24 Comanche single-engine aircraft. A variant with counter-rotating propellers was designated the Piper PA-39 Twin Comanche C/R.
The Twin Comanche was designed to replace the Piper Apache in the company's line up of products. The Twin Comanche was developed from the single engined Comanche by Ed Swearingen who at the time operated a facility that specialized in the modification of production aircraft. The normally aspirated aircraft was equipped with two 4-cylinder 160 hp (120 kW) Lycoming IO-320-B1A fuel injected engines, but 200 hp (150 kW) engines were available as a modification. A version with turbocharged engines for higher altitude flight was also developed, using IO-C1A engines of the same nominal power. All Twin Comanche engines enjoyed long TBO's (2000 hours for the B1A) and developed a reputation for reliability. The PA-39 was a version with counter-rotating engines (to eliminate the critical engine) that replaced the PA-30 in the early 1970s. The Twin Comanche was produced on the same Lock Haven, Pennsylvania production line as its single-engine cousin; production ceased when the factory was flooded in 1972. Piper chose at that time to focus on its equally-popular Cherokee 140/180/235/Arrow line, manufactured in Florida, and its highly popular twin-engine Seneca, which is essentially a Twin Cherokee Six. The Piper PA-40 Arapaho had been scheduled to replace the PA-39 in the 1973-4 timeframe. Three were manufactured, and the aircraft was already fully certified when the decision was made not to proceed with the manufacture. One of the three Arapahos was destroyed in a flat spin accident in 1973; the test pilot (who was none other than future aviation entrepreneur Clay Lacy) successfully escaped. One was scrapped by Piper. One remains flightworthy as of this writing but is not currently being flown.
The Twin Comanche is a low-wing cantilever monoplane with a retractable tricycle landing gear. The Twin Comanche is the most fuel efficient aircraft in its class. With tip tanks, the aircraft holds 120 gallons (454 l) of fuel. Fuel burn at typical cruise settings is approximately 15.5 gph (58.7 lph) with a cruise speed of 165 kts. It easily climbs to 18,000' (5,500 m) when desired (24,000' - 7,300 m - if turbocharged). When compared with the Seminole (in reality a Twin Arrow), the Twin Comanche goes faster, carries more, burns less fuel, climbs more rapidly and ultimately higher, is quieter, and is more difficult for a novice to land. When compared to the Seneca, which is really quite a different aircraft, the more noticeable differences are in handling. Another contemporary competitor to the Twin Comanche was the Beechcraft Travel Air. A similar airplane in form and function was the Grumman Cougar, which went into production after the Twin Comanche's production run ended.
An early high-ratio of training accidents on the original Twin Comanche was reduced by raising the minimum airspeed at which engine-out flights were conducted. In the 1960s, engine-out stalls were performed as part of multiengine training at low altitudes. This, combined with the Twin Comanche's ease of entry into a flat spin if an engine-out stall is taken too far, led to many early accidents. A revision of training procedures combined with revised placarded speed restrictions for single engine operation as well as a service bulletin which added a rudder-aileron interconnect and leading edge stall strips resulted in significant improvement in the accident rate.
A Twin Comanche was flown in the 1992 and 1994 French Arc en Ciel air races. It is the only US aircraft to have raced twice around the world. In the pilot-skilled races, 1992 pilot and Pioneer Hall of Fame enshrinee and 100 Aviation Hero for the First Century of Flight, Marion P. Jayne and her daughter Nancy Palozola placed second. In 1994 Jayne and her daughter, Patricia Jayne (Pat) Keefer won the FAI Gold Medal in what, so far, is the longest race in history at over 21,000 miles flown May 1-24, 1994. With FAA approval the twin carried a total of 252 gallons in 11 tanks and at maximum power went over 2,100 miles non-stop between Marrakech, Morocco and Istanbul, Turkey in 11:19 hours.
Three versions of the PA30 were produced: the original, a B model, and a C model. The B and C models can carry six passengers and can be identified by the additional side windows. Factory turbocharged engines became available in 1965. These used Rajay turbochargers with manual wastegates operated by twin knobs under the throttle quadrant. They were properly termed "turbonormalized" since the compression ratio and maximum manifold pressure remained unchanged. Pilots were required to use care to avoid overboosting at low altitudes, since no overboost popoff valves were used. Since there was no accompanying power increase, the B/C models simply give owners a fuel vs. passenger tradeoff. The two rearmost seats, occupying the baggage compartment, are quite small.
Total Twin Comanche production was 2156, comprising 2001 PA-30s and 155 PA-39s.
Piper PA-30 Twin Comanche
Four-seat twin-engined cabin aircraft. PA-24 with engine removed and nose faired in and powered by two 160-hp (119-kW) Lycoming IO-320-B1A engines in wing mounted nacelles.
Piper PA-30B Twin Comanche
PA-30 with a third cabin window on each side and an optional fifth or sixth seat.
Piper PA-30B Turbo Twin Comanche
Turbonormalized version of the PA-30B Twin Comanche, powered by two Rayjay turbonormalized IO-320-C1A piston engines.
Piper PA-30C Twin Comanche
Twin Comanche B with new instrument panel, switches, and other minor variations. Optional turbonormalized version.
Piper PA-30-200 Twin Comanche B
Experimental PA-30 with two 200hp Lycoming engines, one only from Piper. However, a number of Twin Comanches were modified with 200hp Lycoming engines under an STC from Miller which was often accompanied by modifications to the dorsal fin, nacelles, and nose. Dual brakes on each main wheel and a nosegear headlight were also available from Miller. An optional turbocharged variant of the Miller Twin Comanche was available as well.
Piper PA-39 Twin Comanche C/R
PA-30 with counter-rotating 160hp Lycoming IO-320-B1A engines and modified wing leading edges.
Piper PA-39 Turbo Twin Comanche C/R
Turbocharged version of the PA-39 Twin Comanche C/R.
Piper PA-40 Arapaho
Developed and fully certified version of PA-39 with entirely different wing and extensive fuselage modifications. Three prototypes only.
Specifications (Piper PA-39)
Capacity: four/six seat
Length: 25 ft 2 in (7.67 m)
Wingspan: 36 ft 9½ in (11.21 m)
Height: 8 ft 3 in (2.51 m)
Wing area: 178 ft² (16.54 m²)
Empty weight: 2270 lb (1030 kg)
Gross weight: 3725 lb (1690 kg)
Powerplant: 2 × Avco Lycoming IO-320-B1A flat-four piston engine with counter-rotating propellers, 160 hp (119 kW) each each
Maximum speed: 205 mph (330 km/h)
Range: 1200 miles (1931 km)
Service ceiling: 20,000 ft (6095 m)