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While the results of an exploding (bursting) tire have long been recognized as catastrophic to personnel and surrounding equipment, little work has previously been performed to quantify the tire burst phenomena. Using the Wright Laboratory Landing Gear Development Facility at Wright Patterson Air Force Base, the pressure wave released by a bursting tire was investigated as part of the United States Air Force sponsored Extended Life Tire program. This evaluation included pneumatic blowouts of F- 16 Block 30 (25.0>x8.0-14) and B-52 (56x16) main landing gear tires. The results of this testing are detailed in this paper and include the identification of: shock wave propagation, attenuation, and distribution, the potential effects on personnel, and recommendations for analysis / prediction techniques.

Although aircraft tires are traditionally tested on external dynamometers, the effects of the curved test surface on normal contact pressure distribution and footprint area of a tire have not been previously addressed. Using the Tire Force Machine (TFM) at the Wright Laboratory Landing Gear Development Facility (LGDF), trends for pressure distribution and footprint area were investigated for concave, convex and flat plate surfaces. This evaluation was performed using the F-16 bias, F-16 radial and B-57 bias main landing gear tires at rated load and inflation pressures. The trends for overall tire footprint behavior indicate that the more convex the surface, the smaller the contact area and the larger the normal contact pressures. Conversely, the more concave the surface, the larger the contact area and the smaller the normal contact pressures. Based on these results, the study recommends a 168″ diameter concave (internal roadwheel) dynamometer for tire wear/durability tests.

Tactical aircraft have tire lives as low as 3-5 landings per tire causing excessive support costs. The goal of the Improved Tire Life (ITL) program was to begin developing technology to double aircraft tire life, particularly for tactical aircraft. ITL examined not only the tire, but also aircraft/landing gear design, aircraft operations, and the operational environment. ITL had three main thrusts which were successfully accomplished: 1) development of an analytical tire wear model, 2) initiation of technology development to increase tire life, and 3) exploration of new and unique testing methods for tire wear. This paper reports the work performed and the results of the USAF sponsored ITL program.

The testing of a titanium matrix composite (TMC) F-15 nose gear outer cylinder is discussed. Two cylinders were fabricated. An entire F-15 nose gear was assembled using the first cylinder. This test gear underwent static structural tests to three critical loading conditions and functional evaluations including load-stroke, rebound snubbing, jig drops and strut stroke cycling. The TMC cylinder successfully completed both groups of testing with no signs of structural or functional degradation.

Design and fabrication of a titanium matrix composite (TMC) F-15 nose landing gear (NLG) outer cylinder is discussed. Results of a field experience survey examining landing gear (LG) operations are also discussed. Weight, supportabilty and cost benefits are summarized for this component and projected for production applications of the material.

An improved high-strength, high-toughness steel has been developed which shows considerable promise for landing gear applications. Previous materials provided high strength or high toughness, but not both. The improved material is a modified chemistry of AF1410 steel with increased carbon and an altered heat treat process. Tensile ultimate strengths (Ftu) of over 260 ksi (1.79 GPa) have been achieved while maintaining plane strain fracture toughness (Klc) in excess of 100 ksh/inch (110 MPa√m). In addition, the material has low sensitivity to environmental factors such as hydrogen embrittlement and stress corrosion cracking.