Table Of Contents


Pitcairn Takes the Autogiro

Pitcairn PCA-1

Pitcairn PCA-2

Pitcairn PAA-1, PAA-2

Pitcairn PA-20 44

Pitcairn PA-18


Pitcairn PA-19 59

Pitcairn PA-22

Pitcairn PA-36

Pitcairn PA-39

Alfaro Autogiro 84

Pitcairn YO-61 g8

Kellett Autogiro Company gg

Kellett Kl-X

Kellett K-2 g9

Kellett Q3

Kellett Sky Ads

Kellett KD-1 (Army Air Corps

Kellett KD-1 A



Kellett XR-2


Autogiro Models & Specifications Chart ^

Final Autogiro Activity

Autogiro in the Future * ^

Theory and Discussion

Brochures and Advertising

Glossary 156


Blackburn Aircraft Advertisement

A "gaggle" of autogiros, PAA-2 at top and five Pitcairn PCA-Z Autogiros below.

(Pitcairn Photo)

A "gaggle" of autogiros, PAA-2 at top and five Pitcairn PCA-Z Autogiros below.

(Pitcairn Photo)

Pitcairn Takes the Autogiro

Harold Pitcairn

Cit-ma C-8 Autogirû loith American Wright ¡-5 9 cylinder aircooled 220 Hp radial engine replacing the usual 180 Hp "Viper"engine. Notice, no turned-up wing lips, yet. Insert Harold F. Pitcairn, Founder nf Pitcairn Aviation, Pitcairn Autogiro Company and Autogiro Company of America. (Pitcairn Photo)

Cit-ma C-8 Autogirû loith American Wright ¡-5 9 cylinder aircooled 220 Hp radial engine replacing the usual 180 Hp "Viper"engine. Notice, no turned-up wing lips, yet. Insert Harold F. Pitcairn, Founder nf Pitcairn Aviation, Pitcairn Autogiro Company and Autogiro Company of America. (Pitcairn Photo)

Harold Pitcairn of Bryn Athyn, a suburb of Philadelphia, Pennsylvania, began experimenting with helicopters in 1923. He worked hard at overcoming the problem of counteracting the torque caused by the rotor. He obtained at least one patent for devices to offset the torque. Working with him was a close friend, Agnew Larsen. Some time earlier, Pitcairn had wanted to form a company with Larsen as Chief Engineer. Larsen declined, saying that he lacked the all-round experience, instead he joined the famous Thomas-Morse Company working under B. D, Thomas. Larsen told the writer during an interview that he had taken a verbal trouncing from Thomas when Thomas- Morse lost the production contract for the Thomas-Morse MB-3 fighter to the Boeing Company. Ironically, when Larsen made the detail production drawings of the MB-3 for the Signal Corps, he did such an excellent job that, using these drawings, Boeing was able to out-bid Thomas-Morse for building Thomas-Morse's own design.

In February of 1925, Pitcairn and Larsen left for a twelve-week tour of Europe. The tour included Britain, France and Germany as well as Spain. On this trip the duo was not able to see the autogiro fly. They did see some movies of earlier flights.

Pitcairn asked Cierva if he would object if the Pitcairn organization made a helicopter out of the autogiro. Cierva merely shrugged and offered, "Go ahead if you can."

Pitcairn then revealed that he would be interested in obtaining manufacturing rights for the autogiro. Cierva assured the two that he had no reason to negotiate with anyone. The Spanish government financed all his experimental wrork. He further said that British, French, German, and Italian aircraft manufacturers had already approached him.

In the late summer of 1928 while Pitcairn's staff of designers was working on a highly advanced, smooth, stressed-skin biplane called the "Super Mailwing," designed to carry the U.S. mail, he returned to Europe and tried once more to negotiate with Cierva. This was the third time. He had tried once again after his 1925 visit. On this third visit, he had a flight in the Cierva C-8 autogiro. He was so impressed with the flight that he ordered one for study in America requesting however, that it be powered by a Wright j5, 220 hp "Wirlwind" engine instead of

The site of the original Pitcairn Field as it is now. A modern low-cost housing development is now across the road.

(Sacks Photo)

Willow Grove Air Base Pictures

The Pitcairn factory at Pilcaim field (now ILS. Navy Air Station) Willow Grove, PA

the 180 hp Viper which Cierva was using in the C-8 in 1925.

Pitcairn put himself and his staff in a position to concentrate their efforts on the autogiro development. He disposed of his airmail line. {Which later became Eastern Airlines.) Pit-cairn's famous Mailwing was being used at that time on his own as well as twelve other airlines, and was to continue in service until 1936.

The C-8 arrived at Pitcairn Field, Willow Grove, Pennsylvania (now the Willow Grove Naval Air Station) in mid-December 1928. It was test flown on December 19 by Herbert Raw-son, a British pilot.

On that day Paul Stanley, a very fine engineer, joined the Pitcairn organization. Paul became one of the foremost rotary-wing engineers.

The autogiro's performance on takeoff and climb was compared with the Mailwing's ability; with Pitcairn flying the autogiro. Pitcairn's Chief Pilot, Jim Ray, flew the Mailwing. The autogiro did such a fine job that Pitcairn completed negotiations with Cierva Autogiro Company (at that time in London) for manufacturing rights, forming the Autogiro Company of America. Pitcairn-Cierva Autogiro Company became the first licensee.

The first Pitcairn Autogiro almost became a Mailwing with a rotor installed. Pitcairn's staff had learned from their evaluation of the C-8 that this was not the way to do it. The result was the PCA-1 (for Pitcairn-Cierva Autogiro!) designed and built especially for the Autogiro requirements. It could not help, however, to show its fine Pitcairn lineage.

Because there was no mechanical rotor spin-up mechanism, the first autogiro required taxiing around the field, increasing the speed gradually to get the rotor up to takeoff rpm. Later a "box kite" tail that could have its horizontal surfaces tilted simultaneously to cause the propeller stream to be deflected up through the rotor was used. Although he used this systemon his PCA-1, Pitcairn thought this system to be an "un-American" way to do things. He proceeded to design a mechanical rotor starter with the help of Machine Tool Design Company.

This unit was attached to the starter mounting pad on the Wright engine. A compressed air starter was used to crank the engine for starting. Credit is given to Jean Nichol, Machine Tool's designer, for the design of a twin-disc clutch and a rotor starter capable of carrying 15 to 20 horsepower to the blades. This was the maximum that Wright Aeronautical permitted to be run through the engine starting gear part of the engine, This turned the forty-two foot diameter PCA-1 rotor up to 80 or 90 rpm in 30 to 40 seconds requiring a very short ground run to

Helicopter Rotors While Running Forward

accelerate the rotor to 120 to 130 rpm necessary for takeoff. Without a torque compensating device, such as a helicopter tail rotor, the autogiro could not leave the ground while the rotor was powered.

Kellett, another licensee joined Pitcairn-Cierva's Autogiro Company of America. Next a successful manufacturer of fixed-wing aircraft, Buhl Aircraft of Marysville, Michigan, Their designer, Andre' Dormoy adapted a Pitcairn-style rotor and fixed wing arrangement to a pusher autogiro which was successfully flown on December 15,1931. The test pilot was Buhl's Jimmy Johnson. Buhl never went further than this first model and did not obtain an approved type certificate.

Pitcairn went on with improvements to the PCA-1 and redesigned it to become the PCA-2. This was the first autogiro to obtain an Approved Type Certificate from the Department of Commerce (later CAA and now FAA).

Pitcairn's original factory was in Bryn Athyn, Pennsylvania. Their first fixed wing airplane was the "Fleetwing" a five-place open cockpit biplane unusual in that it had three cockpits in tandem. The forward carried two, the next, two and the rear cockpit was for the pilot. This craft was built to carry sightseeing passengers at the Philadelphia-hosted Sesqui-Centennial exposition in 1926.

Another airplane was being built by Pitcairn at the same time to race in two classes at the 1926 National Air Races being held at the Sesqui-Centennial. It was first called the "Fleet Arrow," but was later changed to the 'Sesqui-Wing" in honor of the Sesqui-Centennial exposition being held in 1926. The "Sesqui-Wing" surpassed all by winning both races. It was a sleek three-place open cockpit biplane. It was to race in the OX-5 engine class and, by employing a quick-change engine pod and a special crew, in theC-6 engine class.

The Pitcairn Fleet Arrow logo.

The next project was the "Orowing," a three-place OX-5 powered open biplane. It was named Orowing because the wings and tail of the Curtiss "Oriol" were mounted on a Pitcairn-built welded steel tube fuselage. This aircraft was intended to replace the famous World War I Curtiss JN-4 (Jenny) which was being sold surplus to barnstorming pilots.

Pitcairn's famous Mailwing came along next, built first as the model PA-4, a three-place open-cockpit biplane called "Fleetwing 2." Only five were built, most had OX-5 engines, but one had a 125 hp Kinner B-5 engine and one had a 110 hp Warner engine.

The style was redesigned slightly with a Wright Wirhvind ]5,220 hp plant and the model was the PA-5 Mailwing.

It was built for use on Pitcairn's Newark, New Jersey to Miami, Florida airmail line. Mail-wings were also bought and used by fourteen other airmail operators; quite a tribute to this airplane.

The Mailwing was constantly improved through the PA-6, PA-7 and the PA-8. The design of a Super-Maiiwing using smooth, stressed-skin design and having the best lift-to-drag ratio of any airplane ever tested at New York University was under way in the late summer of 1928.

The mail line was sold at the end of 1928 to permit the staff to spend more time on the autogiro project. Fixed-wing production was suspended in about 1931 and the PA-7 production line and spares were sold "as is." About seven sets of completed airplane parts were ready for assembly and most went to local aviators for sport and business use.

Autogiros designs went on, the next called PAA-1, which was said to be a "scaled-down PCA-2" with 125 horsepower. Most of these were modified to PA-20 with a larger rotor or PA-24 with a larger rotor and a 160 horsepower Kinner engine. An improved design was the PA-18, still a two-place open craft; smooth fuselage contours replaced the angular PA-20, PA-24 lines.

The need for a plush cabin autogiro was felt about 1931. Larsen told Pitcairn that there was not an engineer on the staff who had sufficient experience with cabin planes design. When asked who he would recommend, Larsen suggested Bob Noorduyn who was Bellanca's designer. Bellanca built the foremost cabin planes of the time. Noorduyn had also worked with Fokker, Sopwith and Whitworth. These were all prominent aircraft companies of the twenties.

In 1929 Pitcairn contracted for the only autogiro to be built outside his plant other than the original Cierva C-8 which he bought in 1928. The Spaniard who had given him the letter of introduction to Cierva, Heraclio Alfaro, proposed a two-place open cockpit 110 horsepower type. The contract was entered into in the summer of 1929. It was flown first on July 18,1930, and was wrecked on the way to the Cleveland Air Races August 21, 1930. Although having several new and unusual features, Pitcairn did not see enough promise to go on with it. It was not rebuilt after the accident.

Alfaro had tried to get the position of Chief Engineer with the Pitcairn organization. When this relationship never did materialize, he negotiated to build his autogiro for Pitcairn.

Later a fourth licensee, Steere Engineering Company of White Plains, New York, was signed up. They had no previous experience in aircraft manufacture. When Alfaro did not get the job as Chief Engineer with Pitcairn, he went to work with Steere in that capacity. Steere bought a Pitcairn PAA-1 Autogiro, but they never developed a product of their own.

In December of 1930, Pitcairn announced that commercial autogiro production had begun. The machine that was designed for production was the three-place open cockpit PCA-2. The power was supplied by a Wright J6, seven cylinder 225 hp package. Before developments had gone very far, the engine was changed to a nine cylinder Wright of the J6 series. This one developed 300 hp. Some other refinements to the design took place.

Advertising brochures boasted a speed of "well over 100 mph." Landing speed was given as zero. Takeoff distance was described as a short run. Actually the distance necessary to Sift off the ground at full gross weight depended, as usual, on air density and the wind velocity. Normally at sea level with no wind, the run wai about two hundred feet. The rotor, it must bt remembered, was not powered but turned b\ autorotation even during takeoff. A clutch wa< provided to bring the rotor up to a speed of 110/ 120 rpm, but it had to be disconnected befort takeoff because there was no way to offset tht rotor torque that would be present with a driver rotor. A rotor brake was provided to stop tht rotor once the autogiro was on the ground.

The PC A-2 could be slowed to about 20 mpl in the air while still holding altitude and unde adequate control. Descents could be made safe ly at zero airspeed; it did, however, require ; special skill to expertly land the craft after a zerc airspeed descent. The nose must be dropped a precisely the right lime to attain the airspeec necessary for elevator control in landing. Then was no control in the rotor.

Two cockpits were installed, the pilot oc cupied the rear and two passengers could bi carried in the front. A very small baggage com partment was located behind the pilot and wa accessible from outside the fuselage.

The pylon which supported the rotorwas re fined from a four-legged structure to one having three legs. One leg extended forward and thi other two ran aft to the outer edges of the for ward side of the rear cockpit.

A group of Pitcairn aviation pilais. Left to right: ¡im Falkner, Amberse Banks, Jim Ray, and Ben Falkner in front of a Pitcairn PA-f. "MaUwing." (Pitcairn Photo

Pitcairn PCA1-A showing boxiail for aerodynamic rotor spimtp, before mechanical s tarter.

(Pitcairn Photo)

Pitcairn PCA1-A showing boxiail for aerodynamic rotor spimtp, before mechanical s tarter.

(Pitcairn Photo)

The PCA-1 could be recognized by its four-legged pylon. Earlier it was equipped with a boxlike tail. The tail could be set nearly vertical so that the propeller si ream would pass up through the rotor blades and bring them nearly up to takeoff speed. It also had an elaborate set of flying and landing wires on the wings. When the box kite tail was removed later, the vertical fin was carried all the way up to the cockpit behind the pilot's headrest. The fuselage was made from aluminum alloy tubing by the Hail Aircraft Company of Buffalo. The covering was fabric over a heavily faired superstructure. The construction of the box tail is not a matter of record but it is assumed to be aluminum alloy. It was definitely fabric covered. Wings were made with wood spars and ribs with fabric covering.

The engine was a geared Wright R-760 "Whirlwind" which developed 240 hp at 2,000 engine rpm, A novel magnesium three-bladed ground adjustable propeller 10 feet in diameter was installed. Rotor blades for this model were made by Cierva in England. They were covered with a very thin mahogany plywood with a natural wood finish.

The design nearly became a modified Mail-wing with an autogiro rotor added. Instead, all components were designed and built to fill autogiro requirements. Cierva's autogiros had been airplanes modified to install his rotor systems. Too much penalty in weight and other compromises were found when Pitcairn evaluated the C-8 so that the decision was immediately made to design the complete autogiro.

It had been found in tests with the C-8 that the machine lacked directional stability. It was decided that it was caused by the large mass of the rotor high above the e.g. of the autogiro. Turned-up wing tips were soon added to the C-8 to help correct this, and they were to be characteristic and symbolic of the autogiro for Some years.

To make the craft stable on the ground, a landing gear tread of twelve feet was used. The main elements of the PCA-1 landing gear were streamlined heat treated steel tubes welded into "vee" assemblies to carry the axles and "N" assemblies to carry the axle loads to the fuselage. The "N" assemblies were braced to each other and to the lower side of the fixed wing with alloy steel streamlined rods. The same type of tie rods continued the landing gear structure from the top of the wing to the fuselage. The welded "vee" assemblies were hinged to the lower end of the "N" struts and connected the lower end of the hydraulic shock struts. The upper end of the shock strut was connected to the bottom side of the wing.

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  • Iago
    How rpm need for G82 jet helicopter rotor?
    5 years ago
  • Claudia
    How can helicopter up to flay the sky engine rpm?
    4 years ago

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