The VDT, or "variable discharge turbine," was proposed as an accessory to the Pratt & Whitney R-4360 and Wright R-3350 radial engines as a means of increasing power. The system used a variable nozzle for the engine's turbosupercharger exhaust which could constrict flow and create jet thrust from the nozzle. Like the turbo compound its intent was to recover lost energy that would otherwise just be vented overboard.

In tests it was quite successful and was slated for use on the Convair B-36C, Boeing XB-54, and Republic XR-16/XF-12. None of these projects panned out however. Convair had trouble with high altitude cooling of the R-4360 VDT engine, owing to the necessity of changing the original pusher configuration to a tractor configuration. The Air Force would have had to build wider taxiways for the XB-54, and the Boeing B-52 was in development anyway, and the Air Force chose to order RB-52's rather than the XR-16. Development of the engine was cancelled as well and the Variable Discharge Turbine faded into obscurity.

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