PULSE JET ENGINE.

Static tests made during the month indicated that the thrust was increased by about 12 by having the valve springs adjusted to a .06-inch opening as compared to the normally closed valve spring arrangement. It was also noted that the tail pipe thrust augmentator increased the static thrust by approximately 20. No performance improvement was noted from the use of a ring type fuel nozzle. High speed tests of the engine in a 14-inch diameter free jet with no combustion and with the valve box sealed, showed a drag coefficient of approximately .2 with no force break existing up to Mach number .8. Combustion testing of the standard engine in the free jet at various Mach numbers revealed that the upper limit of operation of the engine was at a Mach number of about .4 or about 300 miles per hour. Thrust, fuel flow, and specific fuel consumption at Mach numbers of .21, .31, .345, and .41 are presented in the text.