Rotary wing aircrafts

• US 4,458,860 A
• Filed: 06/02/1983
• Issued: 07/10/1984
• Est. Priority Date: 12/26/1975
• Status: Expired due to Fees

• Current Assignee: Koji Ogawa
• Original Assignee: Koji Ogawa
• Inventors: Ogawa, Koji
• Primary Examiner(s): Barefoot, Galen L.
• Application Number:
  US06/500,428
• Time in Patent Office: 404 Days
• Field of Search: 244/17.11, 244/17.27, 416/141, 416/244, 416/232, 416/226, 416/233, 416/145, 416/22, 416/102, 416/115
• US Class Current: 244/17.11
• CPC Class Codes: B64C 27/52 Tilting of rotor bodily relative to fuselage of see-saw type construction B64C27/43

Abstract

Rotary wing aircrafts comprise a fuselage having a rotor driving mast extending substantially vertically. A rotor comprising a plurality of rotors is mounted on the mast for at least feathering and flapping movement. The flapping hinge is offset radially outwardly from the axis of rotation. Further, the rotor blades have weights mounted on the outboard tip ends thereof. The arrangement provides a significantly improved controllability of the aircraft.

Claims

1. Rotary wing aircraft having a center of gravity and a pitching axis passing therethrough, said aircraft comprising a fuselage, engine means mounted on the fuselage, substantially vertical rotary driving shaft means mounted on the fuselage and connected with the engine means to be driven thereby, rotary means including a plurality of rotor blades, means for mounting said rotor blades on the rotor driving shaft means at least for flapping and feathering movements including flapping hinge means about which each said rotor blade conducts flapping movement, said flapping hinge means being offset radially outwardly from the rotating axis of the rotary driving shaft means, swash plate means for enabling collective and cyclic pitch control of the rotor blades, said aircraft being characterized by having physical values ##EQU7## the ratio (2√

K/T) being not less than 1.0;

where I_o is moment of inertia of the aircraft about the pitching axis passing through said center of gravity;

W is weight of the aircraft under standard operating conditions;

h is height of the rotor means from said center of gravity;

b is number of the rotor blades;

Zo is centrifugal force which acts on the rotor blades at the rated operating angular velocity Ω

o;

e is radial offset distance of axis of the flapping movement of the rotor blade from rotating axis of the rotor driving shaft means;

C is mean chord length of the rotor blade;

is density of air under a standard atmospheric condition;

R is radius of the rotor means; and

I_R is the moment of inertia of the rotor blade about the flapping hinge.

2. Rotary wing aircraft in accordance with claim 1 in which the ratio of the radial offset distance e to the radius of the rotor R is not less than 2.5 percent.

3. Rotary wing aircraft in accordance with claim 1 in which said rotor means includes at least three rotor blades.

4. Rotary wing aircraft in accordance with claim 1 in which each of said rotor blades has weight means provided at each tip end thereof.

5. Rotary wing aircraft in accordance with claim 1 in which K is not less than 25 1/sec².

6. Rotary wing aircraft in accordance with claim 1 in which said rotor blades are made of aluminum alloy extrusions.

7. Rotary wing aircraft in accordance with claim 1 in which the value T is not larger than 12 1/sec.

8. Rotary wing aircraft in accordance with claim 1 in which the ratio of the lift coefficient of said rotor blades relative to the attack angle is 5.73.

9. Rotary wing aircraft having a center of gravity and a pitching axis passing therethrough, said aircraft comprising a fuselage, engine means mounted on the fuselage, substantially vertical rotary driving shaft means to be driven thereby;

rotary means including a plurality of rotor blades, means for mounting said rotor blades on the rotor driving shaft means at least for flapping and feathering movements, including flapping hinge means about which each said rotor blade conducts flapping movement, said flapping hinge means being offset radially outwardly from the rotating axis of the rotary driving shaft means, swash plate means for enabling collective and cyclic pitch control of the rotor blades, said aircraft being characterized by having physical values ##EQU8## the ratio (2√

K/T) being not less than 1.0 and a physical value Wh which is smaller than Z_o eb;

wherein;

Io is moment of inertia of the aircraft about the pitching axis passing through the center of gravity;

W is weight of the aircraft;

h is height of the rotor means from the center of gravity;

b is number of the rotor blades;

Zo is centrifugal force which acts on the rotor blade at the rated operating angular velocity Ω

o;

e is radial offset distance of axis of the flapping movement of the rotor blade from rotating axis of the rotor driving shaft means;

C is mean chord length of the rotor blade;

ρ

o is density of air under a standard atmospheric condition;

R is radius of the rotor means; and

I_R is the moment of inertia of the rotor blade about the flapping hinge.