A new method is proposed for calculating values of the influence function in the MULTHOPPtype method of solution of subsonic oscillatory lifting-surface theory. This method partially applies ALWAY's iteration method for the steady lifting-surface theory in order to be effective when integration points lie very near to a collocation section. Numerical calculations prove that converged values are obtained in reasonable computer time.
In order to systematically find out the possibilities, the acceptable operating ranges and the performance trends of ramjet engine systems, a survey covering a wide range of the design ratings and its off-design flight conditions (flight Mach numbers of 0.4 to 5.0 in both), has been conducted for the two-engine type of a noseinlet and a side-inlet. This has been done by using a computer program which is able to calculate the steady-state matching point of the engine system under considerations and the component characteristics, which were varied from the lowest extreme value to the highest. Throughout the mappings of wide ranged ope- rating conditions of many different engine con- figurations obtained from the survey, the followings have been concluded: 1) To determine the flight distance and the ceiling which is the highest altitude to be reach- ed, specific range, defined as a fraction of the flight volume (front area times flight distance) to the fuel volume, has been found to be the most significance, because of the larger drag/ thrust forces than the lifting forces acting on a ramjet engine system. 2) With the same engine configurations, the thrust coefficients for a nose-inlet type become greater than those for a side-inlet one in all the cases investigated. 3) Fuel specific impulse of a ramjet engine may exceed 1, 000 seconds at the flight Mach numbers of approximately more than 2.0. 4) Total pressure recovery at the air-inlet has been found to be the most dominant factor to improve the performance of a ramjet engine system, and it must be kept as high as possible during all the flight conditions.