Lockheed Martin's Skunk Works has teamed with Karem Aircraft to jointly develop the latter company's Optimum Speed Tilt-Rotor design one of three candidates for the US Department of Defense's proposed Joint Heavy Lift programme.
The OSTR design was developed under a JHL concept design and analysis (CDA) contract awarded to Karem by the US Army's Aviation Applied Technology Directorate.
Karem and Lockheed will now refine the design under one of three contract extensions, with Bell Boeing's Quad Tilt Rotor and Sikorsky's Variable Diameter Tilt Rotor also expected to receive new deals. The CDA studies identified an advanced tiltrotor as the preferred configuration for the vertical take-off and landing JHL.
Karem believes an advanced tiltrotor eliminates the need to compromise between vertical lift and efficient transport. The OSTR has a variable-speed propulsion system, which allows the proprotors to operate at higher speed in vertical flight for hover performance and lower speed in forward flight for cruise efficiency.
© Karem Aircraft
The Karem design has a variable-speed propulsion system
The JHL programme is being pursued to meet a requirement to manoeuvre US Army Future Combat Systems armoured vehicles around the battlefield. The growing weight of FCS vehicles has increased the payload required from 20t to approaching 30t, and scaled-up designs will be studied under the CDA extensions.