|1957 Piper PA-23/150 Apache
N2287P (sn 23-898)
Photo taken July 2010 @ Oshkosh (EAA AirVenture Fly-in), WI - USA (OSH / KOSH)
|Photo © Marcel Siegenthaler
The Piper PA-23, named Apache and later Aztec, is a 1950s American twin-engined monoplane.
|1976 Piper PA-23-250 Aztec
N404CH (sn 27-7654191)
NMC Aviation - Northwestern Michigan College
Photo taken Jul. 29 2010 @ Oshkosh (EAA AirVenture Fly-in), WI - USA (OSH / KOSH)
|Photo © Marcel Siegenthaler
Design and development
The PA-23 was the first twin-engine design from Piper and was developed from a proposed "Twin Stinson" design inherited when Piper bought the Stinson Division of the Consolidated Vultee Aircraft corporation. The prototype PA-23 was a four-seater low-wing all-metal monoplane with a twin tail, powered by a two 125 hp Lycoming O-290-D piston engines the prototype first flew 2 March 1952. The aircraft performed badly and it was redesigned with a single vertical stabilizer and an all-metal rear fuselage and more powerful 150 hp Lycoming O-320-A engines. Two new prototype of re-designed aircraft now named Apache were built in 1953 and entered production in 1954; 1,231 were built. In 1958, the Apache 160 was produced by upgrading the engines to 160 hp (119 kW), and 816 were built before being superseded by the Apache 235, which went to 235 hp (175 kW) engines and swept tail surfaces (119 built).
In 1958 an upgraded version with 250 hp (186 kW) Lycoming O-540 engines and adding a swept vertical tail was produced as the PA-23-250 and was name Aztec. These first models came in a five-seat configuration which became available in 1959. In 1961 a longer nosed variant the Aztec B entered production. The later models of the Aztec were equipped with IO-540 fuel-injected engines and six-seat capacity, and continued in production until 1982. There were also turbocharged versions of the later models, which were able to fly at higher altitudes.
The US Navy acquired 20 Aztecs, designating them UO-1, which changed to U-11A when unified designations were adopted in 1962.
In 1974, Piper produced a single experimental PA-41P Pressurized Aztec concept. This concept was short-lived, however, as the aspects of the Aztec that made it so popular for its spacious interior and ability to haul large loads did not lend themselves well to supporting the sealed pressure vessel required for a pressurized aircraft. The project was scrapped, and the one pressurized Aztec produced, N9941P, was donated to Mississippi State University, where it was used for testing purposes. In 2000, N9941P was donated to the Piper Aviation Museum in Lock Haven, PA, on the condition that it never be flown again. It now sits there on display.
- PA-23 Twin-Stinson
Original designation of the Piper PA-23 Apache.
- PA-23 Apache
Initial production version, 2047 built (including the Apache E, G and H).
- PA-23-150 Apache B
1955 variant with minor changes.
- PA-23-150 Apache C
1956 variant with minor changes.
- PA-23-150 Apache D
1957 variant with minor changes.
- PA-23-160 Apache E
PA-23 powered by two 160 hp O-320-B engines.
- PA-23-160 Apache G
PA-23 with longer internal cabin and extra window.
- PA-23-160 Apache H
Apache G with 0-320-B2B engines and minor changes.
- PA-23-235 Apache 235
Apache with 5 seats and 235 hp O-540 engines, 118 built.
- PA-23-250 Aztec
Apache G with modified rear fuselage, new fin and rudder and 250hp Lycoming O-540-A1D engines, 4811 built (including sub-variants)
- PA-23-250 Aztec B
Aztec with longer nose for a baggage compartment, six-seats, new instrument panel and changes to systems.
- PA-23-250 Aztec C
Aztec B with either IO-540-C4B5 engines or turbocharged TIO-540-C4B5 as an option, also modified engine nacelles and modified landing gear.
- PA-23-250 Aztec D
Aztec B with revised instrument panel and controls.
- PA-23-250 Aztec E
Aztec D with longer pointed nose and a single piece windshield.
- PA-23-250 Aztec F
Aztec E with improved systems and cambered wingtips and tailplane tip extensions.
- PA-23T-250 Turbo-Aztec
Generally similar to the Aztec F, powered by two TIO-540 piston engines, fitted with a Garret turbocharging system.
United States Navy designation formerly UO-1.
United States Navy designation for PA-23-250 Aztec with additional equipment, 20 delivered later re-designated U-11A.
- PA-41P Pressurized Aztec
Pressurized Aztec concept, 1 built.
- Costa Rica
- El Salvador
- Spain - Spanish Air Force (Escaudrón 912, Escuadrilla de Enlace 905)
- Paraguay - Paraguayan Air Force (Grupo Aéreo de Transporte Especial/GATE)
- United States - United States Navy
Specifications (Piper PA-23-250F, normally aspirated)
Capacity: 5 passengers
Payload: 1,600 lb (725 kg) cargo
Length: 31 ft 2¾ in (9.52 m)
Wingspan: 37 ft 2½ in (11.34 m)
Height: 10 ft 4 in (3.15 m)
Wing area: 207.6 ft² (19.28 m²)
Airfoil: USA 35-B (modified)
Aspect ratio: 6.8:1
Empty weight: 3,180 lb (1,442 kg)
Max takeoff weight: 5,200 lb (2,360 kg)
Powerplant: 2× Lycoming IO-540-C4B5 normally aspirated air-cooled flat-six piston engines, 250 hp (187 kW) each
Propellers: two bladed Hartzell HC-E2YK-2RB constant speed propeller
Never exceed speed: 277 mph (240 knots, 446 km/h)
Maximum speed: 215 mph (187 knots, 346 km/h)
Cruise speed: 172 mph (150 knots, 278 km/h) at 10,200 ft (3,110 m) (long-range cruise)
Stall speed: 68 mph (59 knots, 109 km/h) (flaps down)
Range: 1,519 miles (1,320 nmi, 2,445 km) at long-range cruise
Service ceiling: 18,950 ft (5,775 m) (absolute ceiling)
Rate of climb: 1,400 ft/min (7.1 m/2)