Im curious for no specific reason what the ownership experience is like for radial engines. Nothing crazy like the multi row wasp but the ones in the 220-300 hp range like the Jacob’s, R, and W’s. What kind of oil use per flight out to include what leaks between flights? How do the cylinders and internals hold up compared to traditional flat Lycoming and continental engines? I know there are extra preflight requirements, I’m more interested in if you fight stuck valves like small continentals, bad cams like Lycoming, or general cylinder wear like the others?
Currently own the care and feeding of 3 radial engines (two P&W R-985s on the Twin Beech and one R-1340 on the T6). Have also owned and flown behind several Continental W-670s and a Jacobs.
The Jake is my least favorite, but I acknowledge that my feelings toward the motor may be colored by the fact that it is mounted on a POS Waco YMF-5 that I fly, so there may be some bad feelings due to the association with that particular airframe.
Rough estimate is that 80% of my last 1000 hours have been flying behind radials.
Goods - like Bell206 said, when well maintained, they are very reliable. They also cool, they sound awesome and they are attached to my favorite airplanes.
Downside is they are generally a little more expensive to overhaul (more cylinders). Burn more fuel than flat engines and they intimidate many A&Ps for no good reason other than they just have little experience with them. They are actually fairly easy to maintain, but you need to find people that aren't intimidated. They are every bit as reliable as any flat engine, but IF you do have an issue on the road, expect that it will take longer to fix both from the standpoint of finding someone to trouble shoot and get the appropriate parts/tools (I actually carry my cylinder removal tool kit in the Beech 18 at all times).
I've only had to leave my Beech 18 at an airport and airline home once and that was for a cylinder head failure (head completely separated form the barrel over the mountains of Northern AZ - engine was running a 'little rough').
Like I said above, they are less fuel efficient. The 220hp Continental burns 13 gph. The 450 hp R-985 22-23 gph and the 600 hp R-1340 burns 33 gph.
Oil consumption also higher than flat engines. A typical oil consumption for a lower to mid time radial is 1 qt per hour. My Beech 18 has been pretty consistent at 1 qt per hour per engine. My Waco also used about a qt per hour. My T-6 with a Covington overhaul is more like 3/4 of a qt per hour.
As far as issues or failures I've experienced, I've had the one cylinder head failure and one exhaust valve failure. One attached fuel pump going bad. Some induction system issues (loose induction pipe) and one carb issue that turned out to be just a bad case of carb ice. Interestingly, the only time I ever declared an emergency was for what turned out to carb ice. Carb ice in the T-6 was not like any carb ice I've ever experienced in a flat engine!
