Expendable Main Rotor Blade Study
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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The report presents results of a design study of expendable main rotor blades for the UH-1H helicopter. The objective of the study was to design blades which could eventually be thrown away after extensive damage rather than be sent back to depot for major overhaul. Unit cost, field repairability, resistance to corrosion and erosion, fatigue strength, and damage tolerance were factors considered for maximum cost effectiveness or lowest life- cycle cost. The study was limited to the UH- 1 blade, which requires a structural skin for edgewise rigidity. For an articulated rotor blade, some of the conclusions regarding skin construction and material could be different. The study included development of reliability, maintainability, and cost-effec-tiveness models. The United Aircraft Normal Modes Computer Program was modi-fied to include two- bladed teetering rotor dynamics. The cost model was based upon the present UH-1H aircraft to provide life-cycle cost comparisons with the new blades designed in this study. The study covered two time frames 1972 and 1980. The results showed that a low-cost aluminum extrusion with a fiberglass composite skin is the most cost effective blade for the 1972 time frame. This blade, which has 30 FEWER PARTS, WAS ESTIMATED TO BE 20 cheaper and 75 more repairable than the Bell blade. It is estimated that this blade could save 12 million for a baseline fleet of 1,000 aircraft. For the 1980 time frame, the Sikorsky twin beam all- composite blade has the potential of being twice as repairable as the Bell blade and could save 26 million for a baseline fleet of 1,000 aircraft.
- Laminates and Composite Materials