Control mechanism for model airplanes

Abstract

Radio control model aircraft achieve trim by an offset to the transmitted signal. The offset is generally set by a slider control. A remote control transmitter, is disclosed having a first input device for providing an input signal to which the transmitter is responsive to provide a control signal to control proportionally an operating parameter of a controlled apparatus. The input device has a neutral state, in which the input signal has a value of zero, corresponding to a desired neutral value of the operating parameter. Operation of a second input device causes the transmitter to provide an offset to the control signal in the same sense as any input to the first input device. The offset increases in value until the first input device is in its neutral state when the operating parameter has the neutral value. In the exemplary application, when the aircraft is flying straight and level, the second input device, which may be a push button, is operated. The pilot continues to fly the aircraft straight and level. In doing so the stick input required reduces until the stick is in the neutral position. The increase in the value of the offset preferably takes place at a rate commensurate with the pilot remaining in control throughout.

1 . A remote control transmitter, comprising a first input device for providing an input signal to which the transmitter is responsive to provide a control signal to control proportionally an operating parameter of a controlled apparatus, the input device having a neutral state, in which the input signal has a value of zero, corresponding to a desired neutral value of the operating parameter; and a second input device operation of which causes the transmitter to provide an offset to the control signal in the same sense as any input to the first input device, said offset increasing in value until the first input device is substantially in its neutral state when the operating parameter has the neutral value.  
     
     
         2 . A transmitter as claimed in  claim 1 , which is responsive to the input signal having a value less than a predetermined amount different from its zero to state hold the value of the offset.  
     
     
         3 . A transmitter as claimed in  claim 1 , including means responsive to operation of the second input device to store the contemporaneous value of the input signal and operative to provide an offset to the value of the control signal increases in the same sense as the stored value until the effect of the offset differs by less than a predetermined amount from that corresponding to the stored value.  
     
     
         4 . A transmitter as claimed in  claim 1  or  2 , wherein the controlled apparatus is a model aircraft and the parameter is the position of a control surface.  
     
     
         5 . A mechanism for controlling the orientation of one or more control members the orientation of which determines the attitude or direction of a vehicle, the mechanism having: a first input member which is manually movable in position and biased to a neutral position, the mechanism being arranged to control the orientation of the control member(s) dependent on the position of the input member; a detector for detecting that the position of the input member is not neutral, and a trimmer responsive to operation of a second input member to provide an offset to the control member(s) in a sense determined by the position of the input member, said offset increasing in magnitude until the position of the input member is neutral.