NACA-ACR-L5G31

Abstract

INTRODUCTION <br>Several high-speed military airplanes in dives have encountered difficulties that could not be easily&#160; controlled by normal means. These difficulties, which may consists of diving moments, large changes in crime, large stick forces, tail buffeting, and the like, occur in high-speed dives when the sped of the airplane exceeds the critical speed by a large amount. For those airplanes for which maximum diving speeds are at or near the critical speed, little or no trouble occurs. The more recent fighter airplanes, however, have terminal mach numbers well in excess of the critical much number and, as a result, often encounter difficulties in dives. Determination of the terminal velocity of the airplane is therefore important in order that the probability of encountering trouble in dives may be estimated. <br>The terminal velocity is also important because it forms the outer limits of the V-G diagram. Usually the outer limit of the V-G diagram is established by multiplying the maximum level-flight speed of an airplane by an arbitrary factor somewhat greater than 1.0 The terminal velocity of most recent airplanes, however, generally falls much below this arbitrary maximum speed, and these airplanes are therefore unnecessarily penalized by extra weight because they are designed for conditions that are not reached in actual flight.