Excellent thread. The R-3350 Turbo Compound is a remarkably complex engine. I imagine that the significant advantage to the early jets was the ease of maintainence vs. the large Radials of the time. For those interested and in KC for any reason, go to the Airline History Museum - they are the Save a Connie folks. They have some 3350's out for examination, including a neat cut-away. The radials still have some utility - Air Tractor still manufactures an airplane that has a R1340 P&W (600hp+ I believe). One good person to get on this thread would be T-cart, who made his living with Ag Cats and Air Tractors - he would provide valuable insight into living with a radial on a day-to-day basis.