Stirling was one of the last generation of Rescue & Target Towing Launches built for the RAF and were designated Mk 3 RTTL and were delivered in the mid 1970's. The model is 1/24 scale and is 39inches L.o.a completed November 2015 from donated hull, all else is scratch built. twin 555 motors running at 12v with 2 x 6v 4a sla batteries in parallel, gives a good scale speed, and has about 45min endurance..