FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1946
1946 - 0845.PDF
MAY 2ND, 1946 FLIGHT 435 Helicopter Some Developments Rotating'Wing Aircraft m I BELIEVE I am not making anover-statement when I say thatthe rotary wing to-day is a much bigger and more complicated subjectthan the fixed wing. There is hardly one aspect of the fixed wing which doesnot apply equally well, perhaps in a slightly modified form, to the rotatingwing. But on the other hand, there exist now a thousand-and-one head-aches of the rotating-wing variety which the designer of fixed-wing air-craft is very fortunate to miss alto- gether. '' - Perhaps this sentence from the lec-ture given by Mr. Raoul Hafner last Saturday to the Society of Licensed Air-craft Engineers helps to explain why progress appears to have been so slow inspite of the amount of attention concen- trated on the subject during the lastfour or five years. The story goes back much fartherthan that, of course, and Mr. Hafner himself, now in charge of helicopter de-velopment at the Bristol Aeroplane Co., Ltd., has had many years of experience.Before the war he designed and built the Hafner gyroplane, which was not a helicopter but had a " windmilling " rotor.The machine had many ingenious features and flew quite well. Helicopter projects followed it, and arrangementswere in hand for actual manufacture. One very ingenious design had a fuselage of approximately aerofoil section,the idea being that the rotor slipstream should impinge on this, the resultant force acting in such a way as to counter-act the rotor torque. Details of the Hafner-designed ROTOR SIDE FORCE RAOUL HAFNER A Lecture Qiven to the Society of Licensed Engineers Bristol helicopter have not been dis-closed, but it is certain that his work will play an important part in rotary-wing development. A large section of Mr. Hafner's lecturewas devoted to explaining the funda- mentals of rotating wings, and the dif-ferent types of aircraft of this general class. These, however, may be assumedto be fairly familiar to readers of Flight through various articles we have published, and we therefore propose to deal with certain other aspects of the lecture.Control and stability have been the stumbling stones of helicopter progressfrom the very beginning. It was known and proved in the early days that adirect-lift machine was possible, but how to control it once it was airbornewas the problem. Mr. Hafner pointed out that the normal fixed-wing aircrafthas four '' freedoms of movement'' (speed, pitch, roll and yaw). The heli-copter has a fifth " freedom," the linear acceleration along the vertical axis ofthe aircraft, or in other words vertical ascent and descent. This freedommakes an extra control necessary. Owing to the fact that helicopters operate over speedranges beginning at zero speed, ordinary movable control surfaces are not satisfactory. A very powerful controlexists, however, in tilting the rotor itself, and this is the method now generally used. Other methods have beensuggested and some of them tried. Two general systems of rotor articulation have beenused: tilting of the rotor hub, as in the Autogiro, or a cyclic pitch change in the rotor blades, as used in the ROTOR TILTED TO STARBOARD LOCK-UP GARAGESFOR HELICOPTERS LEVER OF ROTOR THRUST CAUSING ROLL TO STARBOARD Diagram of helicopter seen from the stern, showing tiltedrotor causing roll to starboard. Not an insect colony but Mr. Hafner's suggestion for a heli-copter station of modest but sufficient dimensions.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
