| 摘要 |
An apparatus for use in an aircraft for determining and displaying a reading which is indicative of pressure density at any instant in time, comprises sensing means for determining both ambient air pressure and ambient air temperature at any instant in time, and outputting an electrical signal having a value which varies in accordance therewith. Calculating means are provided for combining those electrical signals and outputting a weighted signal for pressure density having a value based on an index value of zero for a pressure density at sea level when the ambient temperature is 59° F. and the ambient pressure is 29.92 inches of mercury. A microprocessor computer means has random access memory and read only memory, and an output signal driver for outputting a signal indicative of pressure density at any instant in time to a display. The microprocessor includes a lookup and comparator means, and the read only memory contains a plurality of calculated values of pressure density over a range of barometric pressure values. The weighted signal from the calculating means is read by the lookup and comparator means, and compared with values of pressure density stored in the read only memory, so as to determine the value of pressure density at that instant in time, and to display that value. The apparatus will also provide a real time indication of chosen aircraft flying characteristics, depending on the parameters selected, from further lookup tables included in the read only memory. |
