The story of the helicopter

[Music] looking eastward from the control tower at Wright Field on May 18 1942 an astonished operator gave the green light for the landing of the XR 4 [Applause] as this unconventional craft settled quietly to a spot on the ramp the historians of flight may well have noted that the first successful American helicopter had descended from the realm of aeronautical speculation to a very material place on the flight line of the Army Air Forces this event marked the successful termination of the first cross-country flight and delivery of a practical army helicopter made by the Sikorsky Aircraft Division of the United Aircraft Corporation at Bridgeport Connecticut the XR 4 was flown 761 airline miles to Wright Field Ohio where for eight months it underwent experimental flight tests during this entire period only minor mechanical bugs were uncovered in its mechanism a record unique in the history of new type aircraft the helicopter is capable of aeronautical maneuvers unattainable in any other type of airplane it can hover stationary in space indefinitely under perfect control resembling the flight of birds more closely than anything previously designed by man it can fly forward backward sideways or turn on its own axis with equal ease it can rise vertically from a stationary position on the ground and can be safely landed on a level area 20 feet square it's designer Igor Sikorsky began his world-famous career in 1980 with an unsuccessful attempt at constructing a helicopter after 30 years of intermittent speculations on the direct lift principle his plans for a practical helicopter of his own design were carried to a successful conclusion on the 6th of May 1941 he was able to pilot this skinless predecessor of the XR 4 to a world's endurance record for this type of craft he remained a loft for one hour 32 minutes and 26 seconds while most of his reputation has been realized in four engine ships of the fixed-wing type the helicopter principle has never been far from mr. sikorsky's mind the story of the helicopter is four centuries old our earliest existing record of the conception of its principle is to be found in the notebooks of Leonardo da Vinci this simple sketch is so lacking in detail that it may leave one in doubt as to his purpose but the accompanying notes are convincing he writes I say that this instrument made with a HELOCs if well made that is to say of flaxen linen of which one has closed the pores with starch and is turned with great speed the said hellix is able to make a screw in the air and climb high there is no evidence of da Vinci ever having made a model of his machine but there have been others in 1922 the Army Air Forces evidenced their first active interest in helicopter development by sponsoring the Russian born engineer D both azad who built and tested this huge craft F McCook Field Ohio during the captive flight stage of its development we find its progress being observed by General William Mitchell then assistant chief of the Air Force's the both azad apparently had no time for scale models his craft weighed 3600 pounds and was powered by a 220 horsepower engine his best efforts never got it beyond the reach of a six-foot man in spite of its apparently erratic flight characteristics it succeeded in exhibiting and encouraging amount of stability but the results obtained were not striking enough to warrant continuing the project one year after the de Botha sock machine had been abandoned Emile Berliner was attempting to get this faltering craft into the air at College Park Maryland this was his third and most nearly successful model the photographic evidence at hand would hardly support the popular belief that a third attempt is infallible in Italy d'ascanio built this neuron graceful craft in 1930 its record ceiling was 59 feet distance 3,500 feet with varying degrees of success these and numerous other weird crafts rose and fell in the headlines of aviation each contributing something to this pioneer principle of mechanical flight to seemingly insurmountable difficulties proper control in the air and the price paid in weight and power necessary for direct descent appeared to have permanently grounded the helicopter for all practical purposes meanwhile the fixed-wing airplane was making great progress in the conquest of the air as military and civil demands for speed and carrying ability were met and surpassed it became evident at last that aviation was on the beam the way was clear for the tremendous development which has followed but with a fixed wing principle speed in the air means speed and landing and taking off for sustaining altitude speed must be maintained in crossing high mountains in bad visibility with improved machines and the development of flying technique accident rates were reduced encouragingly in proportion to the number of miles flown but the fixed-wing airplane will always have certain limitations a pilot will always have to be a more or less highly trained engineer literally thousands of square miles will have to be tied up in airports worst of all when an accident does occur the loss of life and material is too often total because of these facts and in spite of continual discouragements the direct lift principle of flight has persisted it has not only persisted but in light of recent developments it is reasonable to believe that it may eventually play as important a role as its fixed-wing predecessor had anyone suggested during this early period of development the possibility of The Da Vinci principle of direct lift flight ever being realized its pioneer inventor might well have been quietly amused but for the past 35 years aeronautical engineers have known that it was to lift a flying machine into the air by means of a propeller rotating in a horizontal plane however as recently as 1932 the world's record for helicopter free flight contains such decidedly impractical figures as distance one kilometer duration about 10 minutes altitude 18 meters in that same year professor Heinrich of the famed fokker wolf aeronautical firm began work on a helicopter for the german government his success was such that in the spring of 1938 his craft astonished the aeronautical world by making an exhibition flight inside the Deutschland Halle in Berlin with fly line hana rush at the controls this ship of course broke all existing helicopter records by a considerable margin in fact it has gone into the records as the first successful ship of its type one of the greatest barriers in helicopter design has been torque reaction caused by the large rotor this unusual tendency of the fuselage to rotate in the opposite direction to the rotor was arrested in the FW 61 by the employment of twin rotors placed side by side and turning in opposite directions at the time when the FW 61 was establishing its success practical comparison of its speed and lift were made with that of the autogyro the various designers of the now successful helicopter must pay a tribute to the late senior de la cierva and constructed and flew the first successful autogyro in 1925 the cornu helicopter had succeeded in lifting itself a few feet above the ground as early as the year nineteen nine but no material progress was accomplished in the helicopter field until after the considerable amount of enthusiasm for auto gyros had come and gone weak weakling the helicopter much information of value somewhat similar in appearance the principle difference between the autogyro and the helicopter is that the rotor of an autogyro is not power driven while the autogyro obtains its lift from its rotor the rotor serves only as a wing would serve a conventional aircraft its rotation is auto rotation and is caused by the movement of the ship through the air the autogyro achieves its motive power from a conventional engine and propeller its advantage over the fixed-wing craft may also be considered its kinship to the helicopter that is the rotation of its blades makes it capable of sustained flight at low speed approximately 30 miles per hour extensive tests of the autogyro proved it to be a best-of tricky ship to fly it has however formed an interesting step between the now highly perfected fixed-wing airplane and the direct lift helicopter a few years ago the US Army Air Forces performed extensive tests on the autogyro but the number of ships in the service has never exceeded ten at the conclusion of these tests the development of the helicopter had progressed so far that it was believed to have every advantage of the autogyro plus many more of its own in short while the helicopter can hover the autogyro is compelled to fly over 30 miles per hour in order to sustain altitude an autogyro landing requires a glide angle and leveling off hence more ground space than the 20-foot platform on which a helicopter come gently to rest while the rotor type aircraft was found to be less efficient and power required than the fixed-wing aircraft the compensating advantages of the helicopter were writing an important chapter in the long history of its evolution military secrecy has forbidden us any further knowledge of what if any progress the Germans have made with the FW 61 type of craft since the opening of the war but developments in this country have centered principally around this very convincing sikorsky model which our army has designated xr4 this ship is unique in its single lifting rotor its directional control and torque reaction are very simply accounted for by the single control pitch small rotor at its tail in a fixed-wing airplane the wing is a shape designed to lift and sustain the entire mechanism in the air the wing can do this only when a considerable amount of air flows across it in use the practical arrangement is to move the wing through the air thus the wing speed is the speed of the whole ship and the speed of support can never be 0 actually the rotor blades in the helicopter may be considered as air foils or wings by revolving the rotor it's series of wings acquire a speed of approximately 350 miles per hour at their tips and so deliver the required lift while the forward speed of the ship is still 0 in case of engine failure autorotation and freewheeling of the main rotor of any helicopter are of course essential features if these were not present the machine would fall like a stone when the engine stopped as a helicopter glides to earth it assumes the characteristics of an autogyro maybe landed accordingly as the glide path is inclined that is to say as soon as the machine moves forward in its descent the rate of descent in the glide is reduced under these circumstances its reactions are similar to those of any slow flying fixed-wing aircraft a number of dead engine landings were deliberately and successfully executed by xr4 during its recent flight test lateral and longitudinal control are obtained in this ship by adjusting the pitch of the main rotor blades it may be increased or decreased by the pilot at any desired point in their rotation with a compensating but opposite variation of pitch at 180 degrees as the lift of a helicopter is not dependent on forward motion and as motion in any direction is affected by the main rotor an adjustment of the blades by the pilot will tilt the shift sideways forward or in any direction and so we'll proceed in that manner climbing descending or in level flight as this control is actuated by the stick and the pitch control of the small vertical air screw in the rear is operated by rudder pedals the controls of this ship are not unlike those of a conventional fixed-wing aircraft except that they are quite sensitive and the tendency is to over control throttle operation has been simplified in that climb and descent are obtained by simultaneously increasing or decreasing the pitch of the main rotor blades together with the use of the throttle since an increase of rotor pitch requires more power to maintain the rotor at whatever rpm is desired there is a synchronizing mechanism that opens the throttle as the pitch is increased and thus maintains nearly constant engine and rotor rpm despite pitch changes while at this time the xr4 stands unrivaled in successful performance in the helicopter field the Platt LePage aircraft corporation at Edison Pennsylvania has been working under an Army Air Forces contract on a helicopter of their own design this craft with its twin rotors there's a resemblance to the FACA wolf model while its military designation is XR one its development has been less progressive than the XR 4 it has however been flying with an encouraging amount of success since May 1941 manufacturing names such as Kellet nash-kelvinator and others are also becoming important figures in the Army Air Forces helicopter program competent authority believes that present knowledge is adequate to design and construct a successful helicopter of approximately 6,000 pounds gross weight of which a reasonable percentage should be useful load though high speed is not of first importance it should exceed 100 miles per hour range and endurance are predicted to be such that it should make an extremely useful instrument in combating submarine warfare a series of tests have been conducted by the Army in order to determine the ability of this new type craft to operate from a small landing deck which may be constructed on any seagoing vessel as the weakest link in a chain determines its strength so the slowest chip determines the speed of a convoy delay in assembling the varied units for a mass voyage Harbor congestion on arrival and the employment of a naval escort are expensive items in fact so much is the convoy system a factor of cost and delay in the prosecution of an overseas military operation that any weapon which will permit greater freedom of action for cargo vessels will be of extreme value to our armed forces it is believed that when a sufficient number of helicopters are available ships of any size or speed equipped with small landing platforms they enjoy the individual and independent protection which the helicopter bids fair to offer against the undersea enemy of wartime shipping the more comprehensive of to deep-sea tests which have been conducted with helicopters operating from merchant vessels was made in July 1943 the findings of this voyage were encouraging to the point that it is believed that a helicopter can be operated from a deck of this sort in weather bad enough to prevent the launching of fixed-wing ships from an aircraft carrier [Music] military and domestic prospects for the uses to which a helicopter may be put are unlimited equipped with low pressure floats there are perhaps no more than two types of surface on which a helicopter cannot land and takeoff dense forests and heavy sea with the aid of a rope ladder and the helicopters particular ability to control its position so precisely in space even these circumstances should not be exceptions to its performance of many military missions hitherto impossible or extremely dangerous because of the limitations of high-speed aircraft [Music] [Applause] because forward speed can be reduced to zero zero visibility is practically the only condition which will ground the helicopter a sharp-eyed helicopter pilot can literally feel his way through the air by flying around trees and over large obstacles Colonel H F Gregory who's been in charge of the Army's rotary wing aircraft program since 1936 believes that since the helicopter needs no prepared landing field it may provide excellent liaison and cooperation with ground forces artillery fire may be coached by direct line telephone communication or behind the line missions at night this airplane should be a real threat with no propeller and the muffled exhaust can operate in almost complete silence it can transport personnel and critical material to inaccessible locations rapidly evacuate wounded men near the front and unreal communication wires behind advancing troops over rugged terrain having no wings the helicopter is less likely to be detected in flight than a conventional slow flying airplane hovering stationary in the air it will blend deceptively with the ground pattern below when properly camouflaged in civil life also this versatile vehicle will without doubt close many a link in the chain of practical aircraft operation as with most post-war developments held out to the panting public there will surely be a considerable interval of time before there is a helicopter on every roof and the two helicopter family makes its appearance but there is no question that the superior control and maneuverability of the helicopter will elevate it to a major position in advancement of transportation facilities these scenes show stages of one of the first demonstrations of the helicopter to the American public [Music] another example of manipulative control is staged by the vs-300 the first of the xr4 type helicopters by picking up a small ring on a nose extension while in flight the ring is transported across the area and delivered to a spectator standing by this exhibition took place on delivery of this pioneer aircraft to the ford aeronautical museum in detroit by way of diversion here's a helicopters eye view of a helicopter taking off from the deck of a cargo ship the normal oscillation of the helicopter is considerably exaggerated by the lens of the camera [Music] two of the rotary ships are operating from this vessel in an experimental flight not the action is seen from one helicopter hovering in the air while the second aircraft leaves the deck as it sweeps out over the briny sea the helicopter bearing the camera approaches the deck and lands we need not further enumerate the probable uses to which this fourth dimension of flight may be applied we can however pause to marvel at the fact that simple as its principle may now seem it was conceived 400 years ago and so must be accorded an unusually long period of legend among other principles of science after all these years it's good to know that at last the anxious mother's admonition to her pilot son namely to fly low and fly slowly may now be obeyed [Music]