Report presenting an investigation to determine and improve on the foreign-object-retention capabilities and pressure-loss characteristics of rectractable engine-inlet screens. Testing occurred with two commerically made retractable screens installed in the engine-inlet sections for which they were designed. Results regarding the retention for both the original and modified screens and pressure tests are provided.

Characteristic exhaust velocity of a 200-pound-thrust rocket engine was evaluated for fuel temperatures of -90 degrees, and 200 degrees f with a spray formed by two impinging heptane jets reacting in a highly atomized oxygen atmosphere. Tests covered a range of mixture ratios and chamber lengths. The characteristic exhaust-velocity efficiency increased 2 percent for a 290 degree f increase in fuel temperature. This increase in performance can be compared with that obtained by increasing chamber length by about 1/2 inch. The result agrees with the fuel-temperature effect predicted from an analysis based on droplet evaporation theory. Mixture ratio markedly affected characteristic exhaust velocity efficiency, but total flow rate and fuel temperature did not.

Report presenting an evaluation of a number of factors affecting engine-airframe arrangements in terms of range. Appropriate equations are developed and evaluated for a range of Mach numbers, ramjet and turbojet engines at several cycle temperatures, and two airplane lift-drag ratios. Some of the factors explored include inlet locations, jet cant for lift, engine moments for trim, a combination of the three factors, and the use of boundary layer in the engine.