inch), and so on up to a size 18 (Base number 1 + 17 for the seventeen 1/4 inch increments over the 1 inch base). Lastly, 3/16 inch is added to the coded size for the actual finished bore diameter. Using the size number 18 bore as an example, we can calculate the actual bore size as follows: The first inch is represented by the base number one, and we subtract that one from the size number, 18. This leaves 17 one-quarter inch units, or 17/4, which reduces to 4-1/4 inches. Adding the one inch base number, we now have a 5-1/4 inch bore. Last, we add the 3/16 for a grand total of 5-7/16 inch diameter for each of the two bores in the PD-18 carburetor body. Each carburetor model number includes the style, size and a specific model letter, which may be followed by a revision number. Each application (the specific engine and airframe combination) then receives a "list number" that contains a list of the specific parts and flow sheet for that application. Needless to say, there are hundreds of parts list and flow sheets in the master catalog. Applications Generally, the PS style carburetors are used on opposed piston engines found on light aircraft and helicopters. The engine can be mounted in the nose, tail, wing or mounted internally on the airframe. The engine can be mounted vertically as well as horizontally. PD style carburetors are for inline and radial engines from 900 to 1900 cubic inches. PT style carburetors are usually found on 1700 to 2600 cubic inch engines PR style carburetors are used on 2600 to 4360 cubic inch engines References Notes Bibliography Stromberg carburetor application list, Bendix-Stromberg, undated. Thorner, Robert H., Aircraft Carburetion, John Wiley & Sons, New York & London, 1946 Pressure Injection, Flight, September 11, 1941 Schlaifer, Robert, Development of Aircraft Engines, Harvard University, Boston, 1950 Law, Peter, ADI presentation to AEHS, from AEHS web site Stromberg Aircraft Carburation, Bendix Corp undated, but pre 1940 Bendix Carburetors, Flight, Training manual, RSA Fuel Injection System'', Precision Airmotive Corp. January, 1990 Bendix PS Series Carburetor Manual, April 1, 1976 Engine fuel system technology Aircraft fuel system components Carburetor manufacturers Bendix Corporation