Composite Lift Fan Driveshaft (CLD)

The titanium JSF Lift Fan driveshaft is highly loaded, experiences significant fatigue loads and is carefully designed to dynamic requirements. The Composite Lift Fan Driveshaft (CLD) developed in this program offers significant weight savings and fatigue performance benefits. Two processes are particularly suited to this application - automated braiding and Ultrasonic Tape Lamination (UTL). NAVAIR is applying automated prepreg braiding to F/A-18 E/F airframe production, including a material qualification property database. This substantially reduces risk and cost for the CLD described herein. UTL is used in highly loaded composite driveshafts for a large Navy motor using a novel end fitting attachment featuring a crenulated tooth design. Joint load capacity 28 percent higher than required in the CLD has been demonstrated. In other composite tubular structure, end fitting joints and tubes have been successfully tested to loads up to 1.9 million lb. In this program design trades and structural analyses shall be performed after definition of detailed requirements. Particular design attention is focused on an efficient and lightweight crenulated joint. Tube sections shall be fabricated and structurally tested to validate design and process details. Rolls Royce will collaborate on this effort to maximize opportunities for technology insertion on the JSF. (P-040184)