1. History and Overview of Rotating Wing Aircraft
Photo by Paolo Rosa
Produced by the American Helicopter Society (AHS) International STEM Committee:
Free to distribute with attribution

2. History of Rotorcraft Definition of Rotorcraft
Any flying machine using rotating wings to provide lift, propulsion, and control that enable vertical flight and hover
Rotating wings provide propulsion, but negligible lift and control.
Rotating wings provide lift, propulsion, control at same time.

3. History of Rotorcraft Two key configurations developed in parallel
Autogiro
Close to helicopter, uses many of same mechanical feature
Cannot hover
Unpowered rotor
Helicopter
Powered rotor
Many configurations have been developed
Autogiros flew first!
Autogiro innovations enabled development of first helicopters

4. Autogyro – How it Works Lift Thrust Unpowered Rotor that
Spins Due to Wind Blowing
Through Rotor Like a
Wind Turbine
Relative Wind
No Need for Anti-Torque Since Not Driven
By an Engine Fixed to the Fuselage
Thrust
Control Surfaces

5. Autogyro – How it Works
Kind of like parasailing, except rotor provides lift in addition to drag.

6. Helicopter – How it Works
Powered Rotor
Equal and opposite torque applied to rotor acts on fuselage
Tail Rotor
Thrust
Rotor Thrust
Main Rotor
Drive Shaft
Tail Boom
Cockpit
Tail Rotor
Engine, Fuel, Transmission, etc.
Landing Skids
Controls

7. Helicopter – Need for Anti-Torque
Engine fixed on body – exerts torque on rotor shaft
Rotor shaft exerts equal and opposite torque on body
Many configurations created around anti-torque problem
Autogyros, tip jets, tip propellers, tandem helicopters, tilt wings, tilt rotors, synchcopter -T T

8. Basic Rotor Controls Flap and Lag Hinges Pitch Bearing Rotor Control
Servos
Pitch Link
Swashplate
Red = Rotating
Blue = Fixed

9. Basic Rotor Controls Cyclic control Collective Control
Changes pitch sinusoidally of all blades around azimuth angle (blade rotation angle)
Accomplished by tilting swashplate side to side on gimbal
Collective Control
Increases/decreases pitch on all blades at all azimuthal locations
Accomplished by moving swashplate up and down rotor shaft
Blade azimuth angle ψ

10. Key Problems in Early Rotorcraft Development
Understanding basic aerodynamics of vertical flight
Amount of power to produce fixed amount of lift was unknown
First significant application of aerodynamic theory to helicopter rotors came about in the early 1920s
Lack of a suitable engine
Not until the mid-1920s that engines with sufficient power and with high power to weight ratios suitable for vertical flight became widely available
Minimizing weight
Early engines made of case iron – too heavy!
Aluminum not cheap enough for use on aircraft until 1920

11. Key Problems in Early Rotorcraft Development
Counteracting rotor torque reaction
Tail rotor to counter torque reaction and provide directional control not used on most early designs
Igor Sikorsky was the first to successfully use the tail rotor in the single rotor helicopter configuration we know today.
Providing stability and control
Primary concern was to devise a means of defeating the unequal lift produced on the blades advancing into and retreating from the relative wind when in forward flight
Problems overcome only with articulated rotor and cyclic pitch control
Conquering high vibrations
Vibration was source of many mechanical failures of the rotor and airframe
Reflected an insufficient understanding of the dynamic and aerodynamic behavior of rotating-wings

12. History of Rotorcraft

13. Early Concepts Chinese Top – 400 B.C.

14. Early Concepts DaVinci - 1493
Leonardo da Vinci credited with first idea for vertical flight
Oversized Archimedes water screw
Airscrew consisted of platform with metal helical screw
Propellers made of starched linen, frame made of wire
Just a sketch

15. Enabling Devices Lomonosov - 1754
Russian, Mikhail V. Lomonosov
Very first self-propelled model of a lifting airscrew flown
Coaxial rotor system, spring-driven device
Flown freely and climbed to good altitude
Intended for lifting thermometers and other instruments into the air

16. Enabling Devices Phillips – 1840’s, D’Amecourt – 1860’s
Horatio Phillips, 1840’s
Constructed first steam driven
vertical flight machine
Steam generated by mini-boiler
ejected at blade tips
First time rotorcraft flew under
engine power
Ponton D’Amecourt, 1860’s
Also designed, built, and flew a
a number of small steam
powered helicopter models
Coaxial rotors
Pictured on right

17. Enabling Devices Bright - 1859
Henry Bright, Englishman
First helicopter patent granted by the British Patent Office
Two counter-rotating coaxial two-bladed rotors
Mounted on a vertical shaft

18. Enabling Devices Achenbach - 1874
Wilheim Achenbach, German
Single rotor concept
First side thrusting tail rotor to counteract main rotor torque

19. Enabling Devices Forlanini - 1878
Enrico Forlanini, Italian
Steam driven helicopter model, dual counter-rotating propellers
Forced superheated steam to a high pressure in a small
metal sphere
Flew 40 ft for 20 sec

20. Early Contraptions Cornu - 1907
Paul Cornu, French Bicycle Maker
Vertical flight machine carried human off ground for the first time
Dual rotor, 24 HP gas engine, belt-driven

21. Early Contraptions Breguet - 1907
Louis and Jacques Breguet, French Scientists
Quad-Rotor gyroplane, 40-hp engine,
Briefly carried a pilot off the ground

22. Early Contraptions Sikorsky - 1909
Igor Sikorsky, Russian
Prototype coaxial nonpiloted helicopter
Did not fly due to vibration problems and lack of power

23. Early Contraptions Yurev - 1912
B.N. Yuriev, Russian
Developed single main rotor helicopter
Included collective pitch, cyclic pitch, and tail rotor
Aircraft never flew properly due to lack of power

24. Early Contraptions Ellehammer - 1914
Jacob Ellehammer, Danish
Coaxial rotor helicopter
Short blades attached to 2 large circular aluminum rings
Top ring like a parachute for failures
Aircraft made short hops off the ground

25. Early Contraptions Petroczy – 1920
Stephan Petroczy, Austrian, assisted by Theodore Von Karman
Build and flew coaxial rotor helicopter
Pilot-Observer positioned over the rotors, inflated bags for landing gear
Powered by 3 rotary engines
Machine only flew tethered to ground

26. Early Contraptions Berliner – 1909 to 1920
Emile and Henry Berliner, father and son from United States
Developed coaxial and side-by-side rotor helicopters
First to observe power required decreases when entering forward flight
Side-by-side aircraft: twisted rotor blades
Side-by-side aircraft control: Differential shaft tilt, wings in slipstream

27. Early Contraptions Brennan – 1920
Louis Brennan, English
Single 2 bladed rotor
Rotor driven by propellers on blade tips (no anti-torque needed)‏
Control achieved with servo flaps inboard on rotor
Machine flew successfully inside a balloon shed, crashed on Flight 7

28. Early Contraptions Pescara – 1920’s
Raul Pescara, Argentinan working in spain and france
Coaxial helicopter with biplane-type rotors
First to use cyclic blade pitch
Aircraft achieved short uncontrolled flights

29. Early Contraptions Von Baumhauer – 1924
A.G. Von Baumhauer, Dutch
Single main rotor helicopter
Collective pitch, cyclic pitch
See-saw teetering rotor
Main and tail rotors not connected – difficult directional control
Machine made several short semi-controlled hops off ground

30. Autogyro – First Flight - 1923
Juan de la Cierva, Spaniard
Hinged Blades, standard fixed wing aircraft controls in rotor slipstream
Low speed control difficult, lack of dynamic pressure
Required about a 50 ft ground run

31. Autogyro – Cyclic Pitch - 1931
E. Burke Wilford, American
First rigid rotor to fly
First to use cyclic blade pitch

32. Autogyro – Direct Control - 1932
Juan de la Cierva, Britain
Rotor mounted so shaft can be tilted for control
Led to elimination of ailerons and stub wings.

33. Autogyro – Coming Back Jay Carter, United States
“Personal Air Vehicle”
2-bladed rotor, pusher propeller, tip weights on blades for jump take-off
Rotor slowed in forward flight for reduced drag

34. Early Helicopters Bothezat – 1922
Georges de Bothezat, United States
Quad-rotor, 6 bladed rotors
Controlled by collective, differential collective, and cyclic pitch
Called the “Flying Octopus”
Flew many times successfully at low altitude and low speed

35. Early Helicopters Oemichen – 1924
Etienne Oemichen, French
Quad-rotor Helicopter
Won FAI award for the first helicopter to fly a 1 km standard circuit
Stable and somewhat maneuverable machine

36. Early Helicopters d’Ascanio – 1930
Corradino d’Ascanio, Italy
Built and flew successful coaxial helicopter
Two bladed rotors, flapping hinges, collective and cyclic pitch
Servo tab control on blades
Small propellers on fuselage used for additional pitch control

37. Early Helicopters Bleeker – 1930
Maitland Bleeker, United States
4-Bladed single rotor helicopter
Followed work of Brennan, rotor powered By props on blade tips
Servo tab control on blades

38. Early Helicopters Florine – 1933
Nicolas Florine, Belgium
Built and flew one of the first tandem rotor helicopters
Rotors spun in same direction, but tilted differentially for anti-torque
Flew for 9 minutes to an altitude of 15 ft

39. Early Helicopters Focke – 1936
Henrich Focke, German
Built and flew successful side-by-side rotor helicopter
Three bladed rotors, flap and lag hinges
Longitudinal control via swashplate on rotors
Lateral control via differential collective on rotors
First helicopter to demonstrate autorotation

40. Early Helicopters Weir Company – 1938
Weir Company, Scotland
Side-by-Side rotor helicopter
Cyclic pitch on blades
No collective pitch, altitude controlled by rotor RPM
Small propellers on fuselage used for additional pitch control

41. Early Helicopters Flettner – 1939
Antoine Flettner, German
First synchcopter helicopter
First to show autorotation and return to powered flight

42. Early Helicopters Sikorsky – 1940
Igor Sikorsky, United States
Successful single main rotor helicopter
Flapping hinges and cyclic pitch
Original machine had 3 small tail rotors, later reduced to one
Considered the first practical helicopter

43. Rotorcraft Configurations

44. Single Main Rotor Helicopter

45. Tandem Rotor Helcopter

46. Synchcopter

47. Tilt Wing Aircraft

48. Tilt Rotor Aircraft

49. Tip Jet Driven Rotorcraft

50. Compound Helicopter McDonnell XV –1
Tip jet driven main rotor, very noisy
Pusher propellers
Large wings
First rotorcraft to fly to 200 mph

51. Compound Helicopter
Tip jet driven main rotor, very noisy

52. Compound Helicopter

53. Compound Helicopters

54. Compound Helicopter

55. Compound Helicopter

56. Compound Helicopter

57. Compound Helicopter

58. Compound Helicopter

59. Compound Helicopter

60. Compound Helicopter Sikorsky X2 Technology Demonstrator
Achieved helicopter speed record of 252 kts (290 mph) on 15 September 2010
Retired on 14 July 2011 after 23 successful flights
Led to development of S-97 Raider high-speed scout/attack helicopter