TABLE OF CONTENTS A complete discussion of airfield considerations, as they concern the landing gear designer, would require a volume of its own. Several of the referenced reports, on specific portions of these considerations, are close to 1 in. thick. This chapter must, therefore, be considered a brief summary of the subject, showing only the current methods and generally guiding the reader to various reports for further details.
Although the landing gear designer is not expected to be able to design runways, he is often required to have a working knowledge of their construction and ability to support an aircraft, including the determination of the life of that surface when subjected to aircraft operations. This subject was recognized as far back as the late 1930's, but it steadily increased in importance so that by the 1960's the designer had to contend with specific requirements concerning flotation and airfield roughness.
Two factors influenced the realization that airfield considerations were becoming important: increasing aircraft weight and increased use of unpaved fields (particularly by the military). As depicted in Fig. 12.1, single-wheel loads have increased over the years. Tire pressure have also increased; for instnce, the DC-3 main gear tires were inflated to 50 psi, the DC-7 tires were inflated to 127 psi, and the DC-10 tires to 185 psi. Since tire pressure and tire load are two primary factors influencing pavement stresses, it is obvious that surface strength/landing gear characteristics must be evaluated. The DC-3 operated on grass fields, but the DC-10...
