Pitcairn PA-22
| {{Infobox aircraft begin
| name=Pitcairn PA-22 | image=PA-22_Washington.jpg | caption=The PA-22 demonstrating over Washington, 8 November 1934 }}{{Infobox aircraft type | type=Experimental, direct control autogyro | national origin=United States | manufacturer=Autogiro Company of America | designer= | first flight=April 1933 | introduced= | retired= | status= | number built=1 | program cost= 1933 }} |
The 1933 experimental Pitcairn PA-22 was one of the first wingless autogyros. It was controlled by movement of the rotor plane rather than the usual control surfaces, though initially the much modified lone example retained rudders as a precaution.
Design and development
The first autogyros, while relying on the rotor for lift, were controlled in flight with ailerons, elevators and rudders like conventional fixed wing aircraft. The first United States autogyro to dispense with these was the PA-22, which the pilot manoeuvred by altering the rotor plane with a long hanging stick which reached down into the cabin; such designs were termed direct control autogyros. Direct control meant the aircraft could be controlled at the lowest speed at which sufficient lift was available, rather than the higher speeds required for control surface authority. First flown in April 1933, it was first demonstrated in public in Washington, D.C., on 8 November 1934.
The PA-22 had a three-bladed rotor with a diameter of {{cvt|32|ft|m}}, pylon-mounted over the cockpit. It was connected via a clutch to the nose-mounted, {{cvt|85|hp|kW}} Pobjoy Cataract engine to spin it up, with rotor blades latched at a low angle of incidence, then unlatched for take-off. Uncowled for cooling and driving a two-bladed propeller, the Cataract powered the PA-22 conventionally once autorotation was established, in standard autogyro fashion.
Behind the engine the fuselage of the PA-22 was conventional, with two side-by-side seats in a flat-sided cabin with generous glazing including windows for both upward and downward views. Access was via side doors. Its tail included a constant chord tailplane, mounted above the fuselage, which carried twin fins inboard of its rounded tips. In the early stages of this much-modified airframe, the fins carried rudders as a precaution but experience of direct control allowed their removal.
The PA-22 had a split axle, fixed tailwheel undercarriage. Its design was similar to that of many fixed wing and autogyro aircraft, with the axles and their rearward drag struts mounted on the central fuselage underside. Long shock-absorbing legs were attached to the upper fuselage. The front wheels were further forward than on other aircraft, making the fraction of weight on the tailwheel greater than usual. Because there was no wing lift involved, it was not necessary to lift the tail during take-off. All three tyres were pneumatic and the tailwheel was steerable.
Another unusual feature of the PA-22 was its foldable rotor. Like other autogyros, the rotor blades were hinged to the drive shaft in the plane of the rotor. In flight, each blade's movement was limited to a few degrees by a pin but these could be removed and the blades folded back manually on the ground. With no wings, hangar space was minimized.
The compact footprint when folded encouraged hopes for a roadable version. This emerged as the Autogiro AC-35, aerodynamically similar and with a foldable rotor but with a centrally-positioned engine. This drove a tractor propeller in flight via a long drive shaft and the tailwheel on the ground through another shaft. It did not reach production and most of Pitcairn's later aircraft had wings, though the PA-36 was an exception. Kellett Autogiro Company's slightly later wingless Kellett KD-1 autogyro had more commercial success.
Specifications
{{Aircraft specs
|prime units?=imp
|genhide=
|crew=2
|capacity=
|length m=
|length ft=18
|length in=
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|span note=
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|empty weight kg=
|empty weight lb=600
|empty weight note=approximately
|gross weight kg=
|gross weight lb=1140
|gross weight note=approximately
|max takeoff weight kg=
|max takeoff weight lb=
|max takeoff weight note=
|fuel capacity={{cvt|17|USgal|Impgal l}}
|more general=
|eng1 number=1
|eng1 name=Pobjoy Cataract
|eng1 type= seven cylinder radial
|eng1 kw=
|eng1 hp=85
|eng1 note=
|power original=
|more power=
|prop blade number=2
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|rot number=3
|rot dia m=
|rot dia ft=32
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|perfhide=
|max speed kmh=
|max speed mph=105
|max speed kts=
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|cruise speed kmh=
|cruise speed mph=90
|cruise speed kts=
|cruise speed note=
- Approximate minimum speed: {{cvt|17|mph|km/h kn}}
- Approximate take off speed: {{cvt|25|mph|km/h kn}}
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|never exceed speed kmh=
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|range km=
|range miles=350
|range nmi=
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|ceiling m=
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|ceiling note=
|g limits=
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}}
References
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Further reading
- {{cite journal |title=Notes on the Progress and Problems of Gyroplanes|author= Alexander Klemin|journal= Aero Digest|date= February 1935|volume=26 |page=40-2 |url=https://archive.org/details/aerodigest2619unse/page/n131/mode/2up}}
- {{cite magazine |title=Small Gyroplane May Bring Flying for All |date=June 1935 |page=807 |url=https://books.google.com/books?id=uN4DAAAAMBAJ&pg=PA807 |magazine=Popular Mechanics |publisher=Hearst Magazines |access-date=25 October 2020}}
- {{cite magazine |title=Wingless Autogiro Parks Like an Automobile |date=February 1935 |page=245 |url=https://books.google.com/books?id=yN8DAAAAMBAJ&pg=PA245 |magazine=Popular Mechanics |publisher=Hearst Magazines |access-date=25 October 2020}}
{{Pitcairn aircraft}}
Category:1930s United States experimental aircraft