Indicator device for vertical landings

Claim 1

IN A VERTICAL LANDING AIRCRAFT WHICH HAS IN FLIGHT ALTITUDE, WEIGHT, VELOCITY AND ACCELERATION PARAMETERS EACH A FUNCTION OF THE INSTANTANEOUS POSITION OF THE CRAFT AND THE FUNCTION OF A POWER UNIT PROVIDING UPWARD THRUST AND HAVING AND INSTRUMENT PANEL, A LANDING CONTROL INDICATOR DEVICE COMPRISING A DIAL GRADUATED IN ACCELERATION VALUES AND LOCATED ON SAID INSTRUMENT PANEL HAVING A FIRST AND SECOND MOVABLE INDEX, FIRST DETECTOR MEANS RESPONSIVE TO WEIGHT OF THE AIRCRAFT AND POWER AVAILABLE FROM SAID UNIT TO PROVIDE CORRESPONDING SIGNALS, A FIRST COMPUTER CONTROLLING SAID FIRST INDEX TO MOVE IT OVER SAID DIAL IN RESPONSE TO THE VALUE OF SAID CORRESPONDING SIGNALS TO COMPUTE THEREFROM THE AIRCRAFT MAXIMUM VERTICAL ACCELERATION WHEN SAID POWER UNIT OPERATES AT MAXIMUM POWER AND INDICATES THE COMPUTED VALUE ON SAID FIRST INDEX, SECOND DETECTOR MEANS RESPONSIVE TO THE INSTANTANEOUS VERTICAL VELOCITY OF DESCENT OF THE AIRCRAFT AND ITS INSTANTANEOUS ALTITUDE TO PROVIDE FURTHER CORRESPONDING SIGNALS, AND A SECOND COMPUTER CONTROLLING SAID SECOND INDEX TO MOVE IT OVER SAID DIAL IN RESPONSE TO SAID FURTHER CORRESPONDING SIGNALS SHOWING THAT VALUE OF THE AIRCRAFT VERTICAL ACCELERATION WHICH IF MAINTAINED WOULD ENSURE TOUCH DOWN AT SUBSTANTIALLY ZERO VERTICAL VELOCITY ON SAID SECOND INDEX, WHEREBY THE RELATIVE POSITIONS OF THE TWO INDICES PROVIDE AN INDICATION OF THE MARGIN OF SAFETY BEFORE THE MAXIMUM POWER OF SAID POWER UNIT IS REQUIRED TO AVOID UNDESIRABLE VERTICAL VELOCITY AT TOUCH DOWN.