The Pitcairn PA-34 and Pitcairn PA-33, given the

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

(USN) designation Pitcairn OP-2 and

United States Army The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...

(US Army) designation Pitcairn YG-2 respectively were

reconnaissance In military operations, military reconnaissance () or scouting is the exploration of an area by military forces to obtain information about enemy forces, the terrain, and civil activities in the area of operations. In military jargon, reconnai ...

autogyro An autogyro (from Greek and , "self-turning"), gyroscope, gyrocopter or gyroplane, is a class of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. A gyroplane "means a rotorcraft whose rotors are not engine-d ...

s designed and built in 1936 for evaluation.

Design and development

The

Pitcairn Aircraft Company The Pitcairn Aircraft Company was an American aircraft manufacturer of light utility aircraft. An early proponent of the autogyro, the company, later known as the Autogiro Company of America among other names, remained in business until 1948. ...

built and developed auto-gyros under licence from the

Cierva Autogiro Company The Cierva Autogiro Company was a British firm established in 1926 to develop the autogyro. The company was set up to further the designs of Juan de la Cierva, a Spanish engineer and pilot, with the financial backing of James George Weir, a Scot ...

, trading as the Pitcairn-Cierva Autogiro Company from the late 1920s. Interest in the auto-gyro by the USN resulted in the purchase of two Pitcairn PCA-2 autogyros, modified as two-seat observation platforms, designated XOP-1. Trials with the XOP-1s from 1931 had limited success, but included an operational deployment in

Nicaragua Nicaragua, officially the Republic of Nicaragua, is the geographically largest Sovereign state, country in Central America, comprising . With a population of 7,142,529 as of 2024, it is the third-most populous country in Central America aft ...

from June 1932, with the

United States Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionar ...

(USMC). Following the development of much-improved rotor and control systems, further interest by US armed forces resulted in the Pitcairn PA-33 (YG-2) and Pitcairn PA-34 (XOP-2). These essentially identical aircraft differed mainly in undercarriage design; the PA-33 had fully cantilevered oleo-pneumatic undercarriage legs and the PA-34 had strut mounted split axles with oleo-pneumatic shock-absorbers attached to the top

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

longerons In engineering, a longeron or stringer is a load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural frame ...

. The fuselage was constructed of welded steel tube with fabric covering and light alloy fairings. The 3-bladed folding rotor was mounted on a braced bi-pod with legs fore and aft of the front cockpit. The tail unit consisted of a very wide chord fin and rudder with a strut supported tail-plane sporting up-turned wing-tips. Tail surfaces were constructed of wood with fabric covering and rotor blades were built with steel tube spars and plywood ribs with fabric covering. Accommodation was in tandem cockpits with the pilot in the rear cockpit aft of the rotor support bi-pod and the observer in the front cockpit beneath the rotor head. Power was supplied by a nose-mounted Wright R-975E-2 in a tight-fitting wide chord cowling with blisters to accommodate rocker arms. The engine was mounted with considerable nose-down angle to ensure prop-wash over the rotor to maintain rotation and ease rotor starting. Control of the aircraft was achieved only by use of the throttle and the tilting rotor-head, operated by a hanging control stick in the rear cockpit.

Operational history

The YG-2 and OP-2 were briefly tested by the US Army and US Navy, with limited success. After completing tests with the US Army, the YG-2 was taken over by the

National Advisory Committee for Aeronautics The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...

(NACA). registered as ''NACA 88''. On 30 March 1936, whilst on test, ''NACA 88'' suffered a rotor failure, prompting the crew to perform the first successful bail-out from a rotary-winged aircraft.

Variants

;PA-33: Company designation of the YG-2 for the US Army ;PA-34: Company designation of the OP-2 for the US Navy ;YG-2: US Army trials autogyro (PA-33), 1 built. ;XOP-2: US Navy trials autogyro (PA-34), one built.

Specifications (PA-33 / PA-34)

References

{{USN observation aircraft 1930s United States military reconnaissance aircraft OP-2 Single-engined tractor autogyros Aircraft first flown in 1936