You’re forgetting the Griffon-powered XIV & XVIII, which were a lot faster than the IX/VIII/XVI, which had varying performance, depending on whether thay were configured for high or low level. At low level (for which it was built) the Spitfire XII could walk away from the 190, and Merlin Spitfires, as Jeffrey Quill demonstrated. Beamont was almost lyrical about the Tempest V, which he said he’d have over any other nation’s products at the time. Post-war, though the radial-engined Sea Fury was better, still, and the Hornet was a further improvement on that.
I think even more than that the piston engine was dead. Turboprops were the next generation, until turbojets were more universally available. Commercial aviation made a run with piston engines into the mid fifties but that had more to do with efficiency and reliability. It’s kind of a shame that turboprops weren’t more accepted in commercial aviation, but I predict they’ll have a big comeback soon. Most efficient power there is.
My father was stuck for a while figuring out why B377 Stratocruisers kept dissappearing over the Pacific. Nearly got fired for pointing out the obvious, that the third and fourth row on the R$360 overheated quickly at full power unless the cowl flaps were kept open, which slowed down the a/c and was counterproductive. If a Strat left San Francisco and was followed an hour later by a DC-7, they arrived in Honolulu at the same time. Problem of course was the fact that the Strat was the first-class section of the flight.
My old friend Airman Jim flew around the world in a C-124 in 1968, with stops in such garden spots as Da Nang. Only took seven engines. He was one of three flight engineers it carried on a flight, and there was a crawlway out to the engines for some reason. The problem was that it included climbing through the main gear well. I asked him once what they would do if the a/c had to land while they were servicing the magnetos or whatever it was they did. (In a really slow Memphis drawl) “we weren’t stupid, you know…” but he said that he did scurry back into the fuselage one time soaked in avgas to report that there was 3" of fuel in the crawlway. When he watched “Strategic Air Command” with me., in the part where the B-36 has a wing fire and crash lands, he thought that the a/c would have blown up within a minute.
I suspect I might have mixed up the two types of Spitfires. The Spitfire I meant to refer to had a 5 blade prop, and first saw service sometime in 1944 [banghead]. Plz go eazy on me, my interest is mostly in luftwaffe birds.
But I don’t think a MK.XII could ‘‘walk away’’ from a up to date fw190A (fw190A-4/A-5 that they ecountered when first introduced were probably slower though).The Mk.XII had more or less the same ammount of horsepower as the Mk.IX if i recall correct. But as I wrote earlier my knowledge of anything not luftwaffe is quite [%-)]. And it was also normal that top speed varied from the specifications, about 3% were the “standard difference range” and that is a lot considering how fast the aircrafts were. One example: a plane with a “topspeed” of 530km/h could in the feild have a top speed that waried from 515km/h up to 545km/h. With these aspects in mind all performance tests must be taken with a grain of salt, but you probably knew that.
I’m not gonna say anything more since the discussion is endless and I have a feeling it’s getting out of topic. But feel free to criticise what I write, I might be wrong.
Yes all performance figures are kind of nonsense. Look at how the RAF biplanes were the scourge of the Med. There’s a whole lot less, I’d say nil, difference between the various powerplant arrangements, otherwise we would not have them all, would we?
I’ll stand by turboprops as the next generation.
Inline didn’t work for commercial aviation, at all. Most aircraft operations, in particular the current jets, rely on power unit interchange, not maintenance in field. Changing out a radial was easier than an inline, maybe?
Private Civil aviation for the past 50 years, starting with the Cessna 150, has all been aircooled.
If its piston today it’s a Continental design, and it’s aircooled. Which whatever you want to say is a derivative of the old radial engine. In fact, it’s really a derivative of the Porsche designed Volkswagen opposed four.
Bondo’s right, engines are replaced in the field, not repaired. OBTW, I’m a maintainer in the USN, been doin’ this since 1982… Engines in need of repair are sent from the field (squadron) to the repair facility, sometimes just across the airfield or right onboard the aircraft carrier. Even then, the repairs are limited to replacement of subassemblies/modules. Deep repairs are typically performed by a depot. Ashore the USN blurs a bit the distinction between a depot and off-aircraft repairs.
An air-cooled engined, such as a radial or horizontally-opposed in-line are simpler to replace as a unit because there is usually only the throttle/mixture controls, fuel line and electrical to disconnect/connect. Liquid-cooled engines are tougher to replace because of the cooling lines to/from the engine. Maintenance of the radiator is also a pain as it can easily be damaged and they tend to rust easily. Jet engines are similar to air-cooled engines in that they can easily be removed/replaced as a pod, on the FA-18 series an experienced crew can swap the engine out in less than 30 minutes.
I believe the helicopter would beg to differ, radial engines lived on in helicopter designs well into the 60s. It provided a lightweight high performance aircooled engine that was just what they needed until small turbine engines were practical. These were all uses of existing designs so perhaps you just meant further development was dead.
The Sikorsky H-34 is still quite a capable performer by modern standards with its radial engine far out performing its replacement the UH-1. The turbine conversions make it a little better performance wise, but primarily is a benefit on the maintenace end.
Something I’m not clear on, are radial engines 2 stroke mixing the gas and oil or do they just burn large quantities of oil as a result of their design?
Four cycle. I’m no expert, but one feature of a radial is that it cannot have a sump in the crankcase, and therefore has an external oil reservoir with hoses and connections, an external oil pump and a lot of seals in disandvantageous locations, like the bottom of the engine. Also, oil accumulates in the bottom cyclinders while the engine is not running, which is a total loss when the engine starts.
it’s hard to seal up any air cooled engine of any great size. The ones we all know of tend to leak oil all over the place; even when they’re not running. The one advantage an air cooled radial has over the inline engine is the narrow, and centerally supported main bearing configuration that greatly reduces harmonics in the crank and rods. As one cylinder fires it tends to unload the opposite bearing side. Where as the length of the average V12 used in WWII tended to create a harmonic vibration causing a so called trans tortional flex in the crank unless it was supported by 13 main bearings (doubtfull). This can be seen by the low rpm factors (3000rpm was really getting it). Of course you also need to take in the piston speed as well, and distance traveled per minute by a piston. If both motors were similar in displacement and had a similar number of cylinders the piston speed would be close. Of course they are not. So you gotta give that advantage to the radial engine.
The air cooled cylinders tend to burn piston rings (they used pain old cast iron ones back then) causing excessive wear. Where as a water cooled engine will have it’s piston rings last several times longer (keep all this in mind later). The double bank of cylinders in an air cooled engine do not cool evenly causing problems in everything from overheated main bearings to uneven cylinder seal on the piston rings (advantage to the water cooled engine). The valve gear in a V12 is similar in many ways to an automobile engine, and there’s really not much there to go wrong other than maybe burning a valve or breaking a valve spring. And at 3000 rpm this is not a real problem. Where as the valve gear in a radial engine is pretty complicated, and will develope harmonics problems at low RPMs. Another thing that’s almost never brought up in basic engine design is the induction systems used in aircraft engines. Allison did use some turbo chargers to boost the engines in some P38’s. But most of the time an axilflow supercharger was used. The air comming out of a turbocharger is super heated; thus compounding the problem. That’s why almost nobody put a turbocharger on a V12. The Germans took it a step further and went with water injection as well as nitrious injection. The advantage is that power is similar to supercharging without the horsepower drain on the crank from the blower. You don’t have that with a turbocharger, but you also tend to cook the engine. Advantage is almost null here except that the power is similar between the smaller V12 and the turbocharged radial (some did use an axil flow setup). The real difference was engine life as heat kills engines.
Call it what you want, but the advantage always goes to the water cooled engine as it’s simple engineering.
The only piston engines still flying are aircooled, I believe, except for very well maintained warbirds, but they are not radials, except for very well maintained warbirds. Hmmmm, best of both worlds I guess.
the aircooled engines in the smaller private planes are a boxer type, and are relatively small compaired to the radials. You can seal one of them up pretty good. But (with a six cylinder engine) you still have the problem of burning rings in the inner cylinders. They’re not really a true high performance engine like we’d see in a fighter aircraft, so you won’t see the same set of problems.
The statement was made about radial engines in tanks and helicopters. They were cheap and made a good amount of horse power at the right time, but that’s about all. Lots of Sherman tanks used them, but if you’ll notice, they were always looking for something better. In helicopters, there just wasn’t a good engine out there that fit the bill. But the small gas turbine drove the final nails in the radials coffin. The H34 was used in Vietnam as well as the Flying Banana (whatever the number was), but were already obsolite as the war ramped up.
