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Aviation History
1945
1945 - 0078.PDF
FLIGHT JANUARY IITH, 1945 HELICOPTERS was eqnipped with standard wheel gear, the rther tried out with floats, and it was found that there was little variation in result between the two. In anti-submarine warfare if the submarine is surfaced, the helicopter does not provide an easy target and is capable of erratic manoeuvr- ing to escape the U-boat's guns. In patrolling or searching, its moderate speed permits the occupants to spot surface craft quite easily, and if anything suspicious comes into view, the machine can stop apd descend immediately to investigate. Once the sub. is sighted, the heli- copter can keep^ft in sight until other craft are brought,» the scene, or if the helicopter is equipped with bombs, it can attack. Recent dummy tests have proved that bomb-carrying helicopters are capable of amazing accuracy, the best score being achieved not while hovering but while making a slow glide approach to the target. Heading the military roster are the Sikorsky Models XR 4-5-6. Sikorsky's VS-300, which came out in 1939, was the- first to find a workable solution to the insistent problem of torque reaction. In the VS-300 Sikorsky balanced the torque of the main rotor by means of an auxiliary rotor mounted on an outrigger and revolving in a vertical plane. TJre XR-4 was the first model to be delivered to the A.A.F. The Army and the Navy each have a number of XR-4S in use, and some of this model went to Britain. Controls comprise stick, rudder pedals and pitch control lever with which the throttle is synchronised. Here, again, the rotor shaft is mounted rigidly with respect to the fuse- lage. The entire shaft of course tilts slightly in the direc- tion of flight, but it is a result of the control, not the cause of it. The control is actually accomplished solely by blade-pitch changing. The main rotor blades may change pitch simultaneously, which controls climb, or cyclically, whkiri controls direction of flight, or in any combination of the two. Record Flights The Sikorsky XR-6 recently proved its practical worth and broke all helicopter records when Col. H. F. Gregory, of the U.S. Army Air Forces, and Ralph Alex, Sikorsky engineer, flew 387 air miles from Washington, D.C., to Patterson Field, Dayton. Ohio. This of course was the longest non-stop helicopter flight to date. During that In the Landgraf machine the twia-rotor preferred. Every effort has been made to pr exterior. The Platt-le Page helicopter also has twin rotors. The outriggers which carry the rotors are streamlined and of ordinary wing form. flight the helicopter was in the air 4 hr. and 55 min.; longer than any helicopter had ever stayed up before. It crossed the Alleghenies at 5,000 feet; higher than any helicopter had previously flown with an equivalent load. It attained the best cross-country helicopter speed; 80 m.p.h. ground speaa despite strong head winds. Experimental Crash The XR-5 and XR-G Sikorsky helicopters embodied great advancements over their prototype. The R-5 was origin- ally intended as an observation craft. Its first flight a little over a year ago was the occasion for a sad debacle, for when the ship was about 70 feet in the air its tail broke off and it was only by a miracle that the test pilot was able to force it into a controlled glide. As it hit the ground a lauding strut was knocked off. The plane careered madly, then turned over and over in a dizzy spin, finally hurtling to destruction. The pilot, amazingly enough, escaped uninjured. But nil despemndum was sttfe motto, and when the R-5 took the air again—and again— as time went on, she demonstrated splendid performance character- istics and excellent load-carrying qualities. The R-5 differs in seating arrangement from the R-4; an R-5, built for two, seats its occupants one behind the other, whereas the two people in an R-4 would find them- selves side-by-side. The R-5 engine is more powerful and its rotor larger than those of other helicopters. The R-6 is a well-designed, attractively streamlined air- craft, the latest thing in helicopters. In the cabin of the XR-4 view is entirely unobstructed forward, upward and to either side. Additional transparent panels in the side, nose and floor, provide good view at downward angles and directly underneath as weflf The cabin of the XR-6 also offers almost perfect unobstructed view, but this cabin is constructed from one single piece of Plasticglass. The 245 h.p. Franklin motor of the XR-6 drives the helicopter "dmum speed of no m.p.h. or more. Page Co. have concentrated their efforts on a helicopter whose design is similar to the German lf idea. Heavier than any other helicopter now this inachine weighs about 4,800 lb. and is powered 450 h.p,. engine. The rotors turn in opposite direc- ' counteracting each other with respect to torque effect "averting the necessity for a tail rotor, aese machines and others which have been pressed into service will be turned to vital commercial purposes in years immediately following the war. Thereafter heli- j>ters for private ownership will come more and more within the public ken until mass production is inevitable. Ope thing is certain. We stand on the threshold of a new industry—and few are the variations which will remain untried in the helicopters of the vast unexplored to-morrow *vhich awaits us beyond the war-reddened horizons of to-day. [Qne point to be borne in mind is that, when all the control and stability problems have been solved, the heli- copter requires more power for vertical than for slanting take-off, a fact which will be/against the cheap low- powered type.—ED.] '
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