An Assessment of the B-747's Capability to Operate on Rough Surfaces
WRIGHT LAB WRIGHT-PATTERSON AFB OH
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A study has been conducted to determine the capability of the Boeing 747 to operate on rough runways specifically, runways that have been damaged by bombing and repaired rapidly using current Air Force procedures. The quality of the repairs has been determined that will allow the aircraft to operate from the repaired surface without being subjected to loads on the landing gears that exceed design limit load. This study indicates that the B-747 is capable of taking off on a repaired runway at 836,000 lbs gross weight provided that repairs in the first 500 feet of the takeoff roll are at least class B. Repairs further down the runway only need to be class E. If the aircraft will traverse two repairs, tables are provided that give the minimum spacing between repairs. Consideration is not given to traversing more than two repairs. Analysis indicates that the ability of the nose gear to withstand loads produced by traversing repair profiles can be significantly improved by increasing the precharge pressure in the shock strut. A nose gear precharge of 185 psi will reduce the peak loads sufficiently to permit a class C repair to be at any position on the runway, including the first 500 feet. Increasing the precharge pressure to 272 psi will permit class E repairs to be located anywhere. At the maximum landing gross weight of 666000 lbs, none of the repairs A through E produced loads that exceeded design limit load during taxi at any speed. The landing touchdown, however, was not considered in this study. Until such time as an analysis becomes available, it should be considered that no repairs can be located in the touchdown area.
- Civilian Aircraft
- Terminal Flight Facilities