The B-36 aircraft was initally powered by 6 piston engine propellers in a trailing-edge mounting (the propellers were aft of the wing). However, later in its service life, these were augmented by four jet engines.
The aircraft were the last large piston-engined bombers built as part of a World War II program. They could fly at heights up to 55,000 feet, and were thus able to fly higher than anti-aircraft defences of the time could reach. At extreme altitude they were even able to out turn jet fighter aircraft such as the F-86 due to their enormous wing area. Four developments spelled the end of the operational life of this type. One was supersonic jet interceptors which could actually attempt to intercept the aircraft with a reasonable chance of success. Another was the advent of surface to air missiles, which greatly increased the height at which ground-based air defences were effective. Thirdly, pure jet powered bombers came online. Fourth was airframe fatigue, since the technology of the B-36 was actually less advanced than the B-29, rendering the aircraft more susceptible to metal fatigue. Only a few full power take-offs, using all ten engines could be made before the airframe concerned had to be retired on safety grounds. They were out of service by the mid-1950s.
Other sites with info on the Convair B-36 include:
Smithsonian's Air and Space Magazine article from 1996: " class="external">http://www.airspacemag.com/ASM/Mag/Index/1996/AM/bacr.html A group of B-36 veterans have a site dedicated to information about this plane: http://www.cowtown.net/proweb/B36_Home.htm