Determination of the transmission efficiency of an aircraft aerosol inlet

Data are reported for both airborne and wind tunnel testing of the aerosol inlet on the CIRPAS Twin Otter research aircraft. Though utilizing different instrumentation and assumptions, results from the two test venues show broad agreement. The roll off in transmission efficiency of the inlet under standard flight conditions starts at similar to 3.5 mu m but plateaus at 5.5 mu m particle diameter at a value slightly in excess of 0.6. This value persists to the upper limit of the test range at 9 mu m and is likely due to the sub-isokinetic aspiration flow of the inlet.