Pedal force trimming device

Claim 2

A helicopter, comprising in combination: a frame; tail rotor blade means having a variable pitch orientation; means for rotatably mounting the blades on the frame, a turbine engine mounted on the frame for providing said blades with an angular velocity, and including a compressor having a discharge pressure, mechanical linkage for controlling the pitch orientation of said blades so that said blades produce a thrust which is dependent upon the pitch orientation and the angular velocity of said blades; the rotation of said blades producing at least one force tending to orient said blades in a pitchless condition thereby producing a load on said linkage means which must be opposed to maintain a predetermined pitch orientation, and compensator means cooperating with said linkage means and responsive to the discharge pressure of the compressor for applying directly to said linkage means a second force in opposition to the force on said linkage means for maintaining the predetermined pitch orientation on the blades.

Claim 3

A helicopter as set forth in claim 1 wherein said compensator means is operative to apply said second force to said linkage means, and said second force being equal in magnitude and opposite from the force tending to alter the predetermined pitch on said blades whereby the load on said linkage means is effectively opposed.

Claim 4

A helicopter as set forth in claim 1 wherein said compensator means includes a pressure piston device having a piston movable within a housing in response to variations in discharge pressure of said compressor, piston rod means movable in response to movement of said piston and cooperating To apply a force to said linkage means proportional to the discharge pressure of said compressor.

Claim 5

A helicopter as set forth in claim 3 wherein said linkage means includes a bell crank, said pressure piston device being mounted to said frame for pivoting movement relative thereto, said piston being mounted on said bell crank for pivoting movement relative thereto, said bell crank being pivotally mounted on said frame and having an angle with respect to the frame which is dependent upon the pitch orientation of said blades, and said discharge pressure of said compressor being operative to apply a force to said bell crank which substantially equalizes the force tending to orient said blades in a pitchless condition.

Claim 6

A pedal force trimming device for use in a helicopter powered by a turbine including a compressor and wherein said helicopter includes main rotor blades, tail rotor blades for maintaining the helicopter in a desired disposition about a vertical axis, foot pedals connected by movable linkage means and operative in response to force applied to said pedals to vary the pitch of said rotor blades depending upon the position of said foot pedals, and wherein forces are created during operation of said helicopter tending to orient said tail rotor blades in a pitchless orientation and producing a force on said pedals which must be overcome to maintain a predetermined pitch orientation thereof, said pedal force trimming device comprising: compensator means directly engaging the movable linkage means and responsive to the discharge pressure of said compressor to provide a balancing force operative on said linkage which aids in maintaining the predetermined pitch orientation of said tail rotor blades in the absence of force applied to said pedals.

Claim 7

A pedal force trimming device for use in a helicopter powered by a turbine including a compressor and wherein said helicopter includes main rotor blades, tail rotor blades for maintaining the helicopter in a desired disposition about a vertical axis, foot pedals connected by movable linkage means and operative in response to force applied to said pedals to vary the pitch of said rotor blades depending upon the position of said foot pedals, and wherein forces are created during operation of said helicopter tending to orient said tail rotor blades in a pitchless orientation and producing a force on said pedals which must be overcome to maintain a predetermined pitch orientation thereof, said pedal force trimming device comprising: compensator means directly engaging the movable linkage means and responsive to the discharge pressure of said compressor to provide a balancing force operative on said linkage which aids in maintaining the predetermined pitch orientation of said tail rotor blades in the absence of force applied to said pedals.

Claim 8

A pedal force trimming device as set forth in claim 5 wherein said linkage has an inherent resistance to movement which provides a second pedal force which aids in maintaining the predetermined pitch orientation of said tail rotor blades, and said compensator means providing a third force with a magnitude which differs from said balancing force by less than the second force whereby said second force in combination with said balancing force provides sufficient force to said linkage to maintain the predetermined pitch orientation of said tail rotor blades in the absence of force applied to said foot pedals.

Claim 9

A pedal force trimming device as set forth in claim 6 wherein the linkage means includes a bell crank having a variable angular displacement dependent upon the pitch of the tail rotor blades, and said compensator means pivotally engaging the helicopter and the bell crank to exert on the bell crank a turning movement dependent upon the discharge pressure of the compressor and the pitch of the tail rotor blades.

Claim 10

A pedal trimming force device as set forth in claim 7 wherein said compensator includes: a rigid housing pivotally engaging the helicopter and including a first and second cavity, a diaphragm fixed to the sides of the housing and movable interiorly of the housing to form said first and second cavities sealed from each other, the first cavity communicating with the compressor to provide a pressure on the diaphragm, a piston movable with the diaphragm and extending through an end of the housing to pivotally engage the bell crank, whereby the piston exerts a force on the bell crank which is dependent upon the discharge pressure of the compressor, and the moment arm of the force thus applied being dependent upon the pitch of the tail rotor blades.

Claim 11

A helicopter including: a frame, a turbine engine fixed to the frame for driving said helicopter and including a compressor providing a discharge pressure, rotatable main rotor blade means driven by the engine to produce a first force tending to rotate the helicopter in a direction opposite to the rotation of the main rotor blade means, rotatable tail rotor blade means Driven by the engine to produce a second force on the helicopter opposing the first force, the magnitude of the second force dependent upon the pitch of the tail rotor blade means, movable control means including foot pedals cooperating with the tail rotor blade means to vary the pitch of the tail rotor blade means to a predetermined pitch orientation, the relative predetermined position of said control means being related to the pitch orientation of said tail rotor blade means, the rotation of the tail rotor blade means producing a third force tending to alter the pitch orientation of said tail rotor blade means and tending to alter the relative position of said movable control means, the third force having a magnitude dependent upon the pitch of the tail rotor blade means and normally opposed by application of force to the foot pedals of said movable control means opposite in magnitude to said third force, compensator means cooperating with said movable control means to maintain the predetermined pitch orientation of said tail rotor blade means by applying a force to said movable control means preventing movement thereof from said relative predetermined position, and said compensator means including means responsive to said compressor discharge pressure to apply a force to said movable control means to maintain the relative predetermined position thereof whereby said predetermined pitch orientation of said tail rotor blade means is maintained in the absence of applied additional force to the foot pedals of said movable control means.

Claim 12

A helicopter including: a frame, a turbine engine fixed to the frame for driving said helicopter and including a compressor providing a discharge pressure, rotatable main rotor blade means driven by the engine to produce a first force tending to rotate the helicopter in a direction opposite to the rotation of the main rotor blade means, rotatable tail rotor blade means Driven by the engine to produce a second force on the helicopter opposing the first force, the magnitude of the second force dependent upon the pitch of the tail rotor blade means, movable control means including foot pedals cooperating with the tail rotor blade means to vary the pitch of the tail rotor blade means to a predetermined pitch orientation, the relative predetermined position of said control means being related to the pitch orientation of said tail rotor blade means, the rotation of the tail rotor blade means producing a third force tending to alter the pitch orientation of said tail rotor blade means and tending to alter the relative position of said movable control means, the third force having a magnitude dependent upon the pitch of the tail rotor blade means and normally opposed by application of force to the foot pedals of said movable control means opposite in magnitude to said third force, compensator means cooperating with said movable control means to maintain the predetermined pitch orientation of said tail rotor blade means by applying a force to said movable control means preventing movement thereof from said relative predetermined position, and said compensator means including means responsive to said compressor discharge pressure to apply a force to said movable control means to maintain the relative predetermined position thereof whereby said predetermined pitch orientation of said tail rotor blade means is maintained in the absence of applied additional force to the foot pedals of said movable control means.

Claim 13

A helicopter as set forth in claim 9 wherein said third force is a variable force dependent upon the particular flight regime of said helicopter and the pitch of said tail rotor blade means, and said compensator means being operative to apply force to said movable control means which is variable but of a magnitude opposite that tending to cause said tail rotor blade means to assume a pitchless orientation in the particular flight regime.

Claim 14

A helicopter as set forth in claim 9 wherein: said movable control means includes linkage means operatively controlling said tail rotor blade means, the relative position of said linkage being related to the pitch orientation of said tail rotor blade means, and said compensator means cooperating with said linkage means to produce a force moment thereon dependent upon the magnitude of said first force and the pitch of said tail rotor blade means for maintaining the related position of said linkage and the related pitch orientation of said rotor blade means.

Claim 15

A helicopter as set forth in claim 9 wherein: said means responsive to said compressor discharge pressure include a pressure piston device, having a movable piston, said piston having a diaphragm member cooperating therewith and dividing said piston device into two cavities sealed from each other, means for coupling the discharge pressure of said compressor to one of said cavities to produce a force to urge said piston in the other of said cavities, and piston rod means cooperating with said piston to transmit said force to said control means.

Claim 16

A helicopter as set forth in claim 12 wherein said control means includes a bell crank, and said piston rod being connected to apply a force to said bell crank which is dependent upon the pressure on said piston.

Claim 17

A helicopter having an engine and main rotor blades producing a thrust dependent on the power of the engine comprising: tail rotor blades having a variable pitch orientable to a predetermined condition for maintaining the stability of said helicopter, said tail blades being subjected to force conditions tending to orient said tail blades towards a pitchless condition, the engine providing a fluid with a particular pressure and being related to the thrust of the main rotor blades, control means operative to vary the pitch of said tail rotor blades, said control means including linkage means anD foot pedal means, said force conditions creating a load on said linkage means and effective on said foot pedal means, and a pressure piston device connected to said control means and responsive to the pressure of said fluid to apply a force to said linkage means opposing the force conditions tending to alter the pitch condition of said tail blades towards a pitchless condition whereby the load effective on said foot pedals is sufficiently reduced to maintain a predetermined pitch condition of said tail rotor blades in the absence of an additional applied force.

Claim 18

A helicopter having an engine and main rotor blades producing a thrust dependent on the power of the engine comprising: tail rotor blades having a variable pitch orientable to a predetermined condition for maintaining the stability of said helicopter, said tail blades being subjected to force conditions tending to orient said tail blades towards a pitchless condition, the engine providing a fluid with a particular pressure and being related to the thrust of the main rotor blades, control means operative to vary the pitch of said tail rotor blades, said control means including linkage means anD foot pedal means, said force conditions creating a load on said linkage means and effective on said foot pedal means, and a pressure piston device connected to said control means and responsive to the pressure of said fluid to apply a force to said linkage means opposing the force conditions tending to alter the pitch condition of said tail blades towards a pitchless condition whereby the load effective on said foot pedals is sufficiently reduced to maintain a predetermined pitch condition of said tail rotor blades in the absence of an additional applied force.

Claim 19

The helicopter set forth in claim 14 further comprising: a bell crank included in the control means and having an angular displacement dependent on the pitch of the tail rotor blades, and wherein the pressure piston device pivotally engages the bell crank.