October 2005 - American Bonanza Society

FLYING THE AUTOGIRO ATTHE NATIONAL AIR RACESBY JOHN M. MILLER. POUGHKEEPSIE, NEW YORKAt the famous National Air Racesthat were held several yearsbefore WWIl at Cleveland,Ohio, there were two principal types ofparticipants: racers and aerobatics. Theracers competed for prize money, theaerobatics for fees.In 1931, I was the first person tobuy one of the newly developed PitcairnPCA-2 autogiros, a revolutionary aircraftat that time, and I made exhibitionflights at Cleveland that year.The PCA-2 had an open cockpitfuselage, seating two passengers in thefront and a single pilot in the rear. Theengine was a 330-hp Wright nine-cylinderradial with fixed-pitch tractor propeller.The empty weight was 2,000pounds and it carried 39 gallons of fuelin its main tank, plus 20 gallons in areserve tank.There was no electrical system,thus no instrument lights, battery, electricengine starter or radio. There waswiring for the position lights, if a drybattery was temporarily carried. Theinstruments had self-glowing dials. Theengine starter was the Heywood airpressuretype, very satisfactory. The tailwas the normal configuration as on airplanes,but only a small rudder wasrequired, and the elevators had abouttwice the area as the stabilizer.Contrary to ru mors, there was sufficientcontrol at zero airspeed in a verticaldescent, due to air escaping fromunder the vertically descending rotor,thus providing airspeed for rudder andelevators. The full span ailerons werenot needed in vertical descents, sincethe aircraft was hanging from the rotorin a stable condition.That ability of the autogiro to makestable and controlled vertical descentsat about the descent rate of a parachuteis one of the wonderful safety featuresof the autogiro. By holding air peed toabout 20-30 mph during descents, theautogiro could be landed with little or noroll, with no power, engine dead oridling. I had one sudden engine failureand did just that at a standstill in acemetery,among gravestones, with no wind.There were small tapered low wingswith upturned tips to provide some lift athigh forward speed, to increase the overallI.JD ratio, since the self-rotating rotorhad a lower ratio than the fixed wings.The ailerons were full span of the wings.One great advantage of the rotor was thatit could not be stalled, even at zero speedor even in a backward slide. The rotorblades had a fixed-pitch setting that guaranteedfull rotation at all times, and couldnot be stopped in the air, either onpurpose or accidentally.The rotor hub was set at a fixedposition on the top of the rotor pylon.Since the rotor blades were connected tothe rotor hub by means of universaljoints, bending stress on the rotor bladeswas avoided and they were held outwardby centrifugal force alone. Theyhad an indefinite lifespan.The rotor was started before takeoffby means of gears and a clutch from theengine. For takeoff, the clutch was disengagedat 120 rpm and takeoff startedbefore it slowed down appreciably. Assoon as a slight forward ground speedwas attained, the rotor self-rotated at 120rpm and takeoff was horizontal but short.This was an aircraft that, to thisday, had the only perfect safety recordfor its occupants, even though mostwere wrecked by untrained pilots. OnePCA-2 is still flown by Steven Pitcairn,and one is in the Ford Museum, atDearborn, Michigan. Besides mine,they are the only ones not wrecked.Mine flew more than 4,000 hours. It