I’m building a 1-D Corsair, and I was wondering how I should weather these bad boys. Did they usually tell pilots to hang on to them for dear life unless jumped by zekes or were they jettisoned more often than not? If they were jettisoned, then I will make the tanks nice and clean while the rest of the bird suffers from carrier syndrome. Does this also apply to other aircraft (P-38, P-51, etc)? Thanks guys, you’re the best!
They would jettison only if engaged in air to air combat. On ground attack missions they would normally keep them. Even with a new tank, the R-2800 engines were oil leakers so the tank would have oil stains on them. Older tanks would have even more oil stains.
All radials are oil leakers – if it’s not spewing oil somewhere it’s probably out of oil! The R755-B2 on my 195 uses about a pint of oil everytime I start it. It goes out the bottom to the point where the spot in front of my hangar is starting to look like a toxic waste site! (They do make clean kits for them now, but that is a modern convenience)
Yeah radials are bad… I saw the P-47 had a 26.4 Gallon oil tank. That’s almost twice as big as my car’s gas tank!!!
What causes radials to leak so much? You’d think they could engineer something air(and oil) tight…
It’s due in large part to being air cooled. The tolerances need to be on the lose side to account for expansion during heating. A liquid cooled engine by comparison operates in a pretty narrow temp range, so i can be made tighter. Also, the nature of the design with at least 2 cylinders hanging straight down ensures that oil will drain down into them. That oil has to go somewhere, and on startup it goes out in the form of smoke, and a fine mist that gets all over everything. A little oil goes a long way when it sprayed at a high velocity. Before starting mine, I have a couple of drains in the oil return line that I open (they are dry sump engines with a remote tank) and then I pull the prop through many times. Depending on where the prop was parked, and which valves were open or closed, I get a decent amount of oil out the exhaust. Or I can get a hydraulic lock, which means that cylinder is so full of oil that the piston hits it a stops – can’t compress oil. Then you have to pull the bottom plugs and drain it, otherwise you’d get a bent link rod or worse. On startup I let the starter take it through several blades before hitting the ignition, as an insurance policy. The clutch in the starter should give it is gets a lock, but if it fires, forget about it. On shutdown, the engine is idled with the prop in the low RPM position, which scavenges most of the oil out of the crankcase and prop and back into the tank, which on mine only holds 5 gallons. There are so many oil lines with their inherent seals and connections, the prop seal is tricky to install without causing very slight damage to it creating another leak source, and so on. Also, the high consumption is part of the design, it isn’t totally an air-cooled engine. The oil does as much cooling as anything, so part of that is consumed due to heating. I have a big decal on my hangar door the the engine overhauler gives out: “Radial engines don’t leak – they are just marking their territory!”