抄録
This paper concerns with the kernel function which appears in the subsonic lifting surface theory. There are two parts. In Part I, evaluation method of the so-called integral function B is discussed. In a previous paper the present authors proposed an improved evaluation method, about which a few "demerits" were pointed out by some readers. These "demerits" however are trivial according to the present investigation. For small k (reduced frequency), an ultra near field approximation formula (BUS) is useful. It is noteworthy that B for small k and/or small W is combined into BUS, where the product kW plays an important role. For small r, the function Qr(r) can be calculated using double precision without any difficulties. In addition an ultra far field approximation formula BUL is effective for kW>50…though it is irrespective of "demerits." Both in Bus and BUL, the product kW is a controlling independent variable. Thus advantages resulting from kX and kr over X and r become much clearer. Part II presents an ideal form of the overall kernel function. The singular terms are written by using the original independent variables, which make analytic treatment much more convenient. On the other hand the finite terms preserve their favourable formes for numerical evaluation.
