April 2005-
There were seventeen direct, certificated descendants and scores of variants in two, three and four-place configurations on conventional or tricycle gear, skis or floats, powered by everything from a 35 hp radial to 180 horsepower flat fours. And the later low-wing PA-28 design produced 15 variations.
That’s not to say that engineers just kept reinventing the Cub and the Cherokee; dozens of new types were tried, as well–both single and twin pushers, and at least one amphibian. In 1940, Piper tested an Applegate Duck amphibian designated P-1 after replacing its Essex automobile motor with a 90 hp Franklin, adding a new wing of their own design and changing it to a pusher configuration. It was not successful.
Next came the P-2, which was a Cub powered by a 60 hp Franklin and later with 75 hp Continental. The P-2 had a cowled engine and one-piece hinged door. The P-4 of 1941 was a four-seat, 120 hp Lycoming powered Cub that was first built with a cambered tail that later changed to a flat adjustable stabilator.
Piper’s first low-wing airplane was the experimental PT-1 Trainer of 1942, a fabric covered tandem two-seater with metal fuselage and wooden spar wings with flaps. It was powered by a 130 hp Franklin engine.
The Model PWA-1 Skycoupe (Post-War Airplane) was a side-by-side two-seat low wing design with twin boom fuselage and powered by a 113 Franklin pusher engine and sitting on tricycle gear.
Later in 1944, Piper published a list of aircraft proposed to be built after the end of the war. One was the PWA-5 Sky Sedan, a four-seater powered by 140 hp Franklin based on the PT-1. When it appeared in 1945, power had changed to 165 hp Continental and designation to PA-6.
A second prototype with 205 hp Continental engine and retractable gear appeared in 1946, but no more were built. PA-8 Sky Cycle—A boom market was anticipated after the end of World War II, and returning servicemen would likely buy the aircraft in which they had trained.
For the most part, that meant Pipers, and the company was poised to build whatever they could. The problem was that the war effort had used up most of the supply of aircraft materials, so engineers in Lock Haven designed a “quickie” model which would utilize non-traditional parts.
The result was the Piper Sky Cycle first flown in 1945. Intended to sell for less than $1,000, it was a single-seater, its fuselage was a sisal-reinforced plastic drop tank from a P-38 fighter–the main load-carrying structure to which was attached a boom for the tail and a wing carry-through section. The cockpit was cut out of the top of the tank and the opening covered with a bubble canopy. Power was provided by a 38 horsepower Continental A-40. At its gross weight of 630 lb. it had a cruise speed of 115 mph and 400-mile range.
While it was apparently docile in level flight, flight testing revealed some mean tendencies in unusual attitudes. That, coupled with a sudden rise in material costs, spelled the end of the project.
PA-29 Papoose
In late 1959, Piper started design work on a fiberglass airplane powered by a 108 hp O-235 Lycoming engine. It was a two-place side-by-side low-winger with fixed tricycle gear. The prototype was produced and flown in 1962 with an airframe of fiberglass-reinforced plastic. It incorporated an all-moving horizontal tail, full-span ailerons which drooped to act as flaps, and fiberglass-sprung main and nose gear legs. The prototype PA-29 now lives at the EAA Museum in Oshkosh, Wis.
PA-32-3M/PA-34-180
Perhaps the strangest Piper prototype ever was the PA-32-3M. After tests on the PA-32-260 Cherokee Six were completed in 1965, engineers grafted two 115 hp Lycoming O-235 engines on the wing of the prototype while retaining the 250 hp engine on the nose, and began testing of the Piper Tri-Motor.
Whether it was merely a test “mule” put to work to explore areas for a proposed twin, or a possible production model is unclear. In any case, it was unique.
With the center engine shut down, however, flight testing demonstrated that the two outboard engines could not sustain level flight, so all three powerplants were replaced with 150 hp O-320 engines (the first installation had a total of 480 hp, the second 450 hp).
The immense drag created by the fixed pitch propellers, plus the expense and complication of installing three sets of controls, cables and associated engine hardware, convinced the company to abandon the concept and return to a conventional twin-engine aircraft. The next project was the PA-34—today’s Seneca—which began test flight with two 180 hp O-360 engines and fixed gear.
PA-33 Pressurized Comanche
During 1966 and early 1967, Ed Swearingen—the designer and builder of Metros, Merlins, SX-300 homebuilt and the Sino-Swearingen SJ-30 jet, and designer of Piper’s prototype Twin Comanche and Cheyenne—produced a pressurized version of the single-engine PA-24 Comanche under contract for Piper Aircraft.
It utilized a 260 hp Lycoming O-540, bigger propeller and longer Twin Comanche landing gear. The prototype first flew in March 1967. Two months later it crashed on takeoff when the test pilot had trouble with the nosewheel steering, and the project was canceled.
PA-35 Pocono
Piper attempted to enter the lucrative commuter airline market in the Sixties with the 16 to 18-place PA-35 Pocono, which was powered by two 475 hp Lycoming TIO-720 eight-cylinder engines. It flew in May 1968, and the factory announced that it would build a $2 million factory at Lakeland, Fla. to produce the airplane.
During development, the prototype’s airframe was lengthened three feet and overall height was increased to improve flight characteristics. But the regional airline business began softening, and the new larger airframe needed even more horsepower, so the project was put on hold until 1970, when Piper proposed three new versions: one with four 250 hp engines; a turboprop model with two 580 shp Pratt & Whitneys; and an 800 shp turbine twin version.
The prototype was moved to Lakeland in 1972, where it languished until it was sold to Polish manufacturer Pezetel in 1976.
PA-40 Arapaho
This airplane was intended as a replacement for the Twin Comanche C/R. It was similar in size to the Twin Comanche, but with longer gear legs, undercambered cuffs at the wing leading edge, larger windows, and hydraulic landing gear. It had two counter-rotating 160 hp Lycomings and was first flown in January 1973. It crashed during September spin trials and was removed from the registry.
Two other prototype Arapahos were built. One was turbocharged, to be launched as a 1975 model, but a shrinking market caused the project to be canceled in December 1974. Five production fuselages which had been built were scrapped, and the two remaining prototypes were given to schools.
Piper Aircraft Co. Experimental, prototype and miscellaneous production 1945-present: 1945 PA-6 Skysedan 1945 PA-7 Skycoupe 1945 PA-8 Skycycle 1945 PA-11 Cub Special 1946 PA-12 Super Cruiser 1948 PA-14 Family Cruiser 1948 PA-15 Vagabond 1948 PA-16 Clipper 1948 PA-17 Vagabond 1949 PA-18 Super Cub 1949 PA-19 Super Cub 1949 PA-20 Pacer 1949 PA-21 Brigadier 1950 PA-22 Tri-Pacer 1950 Twin Stinson 1952 PA-23 Apache 1956 PA-24 Comanche 1957 PA-25 Pawnee 1958 PA-23 Aztec 1960 PA-24 Cherokee 1961 PA-24-400 Comanche 1962 PA-29 Papoose 1962 PA-30 Twin Comanche 1964 PA-31 Navajo 1964 PA-32 Cherokee Six 1964 XPA-33P 1965 PA-32-3M 1966 PA-28R Arrow 1967 PA-31T Cheyenne 1967 PA-33 (pressurized Comanche) 1967 PA-34 Twin Six (Seneca) 1968 PA-31P Navajo 1968 PA-35 Pocono 1969 PA-36 Pawnee Brave 1972 PA-40 Arapaho 1974 PA-32R Lance 1974 PA-41P 1976 PA-44 Seminole 1978 PA-38 Tomahawk 1979 PA-46 Malibu
• The PA-32-3M was a tri-motor Cherokee Six test mule from which the Seneca was developed.
• The PA-33 Pressurized Comanche first flew in 1967, but when the prototype crashed the program was canceled.
• The PA-35 Pocono was Piper’s intended entry into the commuter airline market in the 1960s.
• The PA-40 Arapaho was an upgrade of the Twin Comanche C/R, but was dropped when the twin market softened in the 1970s.
Daryl Murphy has been writing about flying and a variety of aircraft for 36 years. In addition to this magazine, his work appears in General Aviation News and Aviation International News. He has written five aviation books and one on automobile racing.
