I’m somewhat familiar with the P&W R985 radial engine of pre WWII vintage These are very common in our local seaplane service, as they are used both in Beavers and twin engine Beechcraft.
Not being familiar with in-line engines for aircraft though, what did amazes me is the versatality of the radial engine. Engine cylinders can be easily replaced when they crack, and losing one of 9 cylinders in the air is no big deal. One local company uses gas from a local marine/automotive outlet rather than the more expensive aviation fuel. The savings exceeds the cost of increased frequency of cylinder failure.
Of course, a great many land-based fighters had radial engines as well, including the P-47 Thunderbolt, FW-190, most Japanese land-based fighters, at least some Tempest models, and others. Most engines for multi-engine aircraft, IIRC, were radial models, though I could be wrong about that. Radial engines, by and large, were the engine of choice.
Perhaps it’s just chance that no inline-engined models ever caught on for naval use - aside from the Seafire.
I’m quoting from a book I don’t own any more and haven’t read in twenty years, but I seem to recall a passage in Pappy Boyington’s autobiography where he talks about the transition in skills that was necessary when he joined the Flying Tigers and went from flying a radial-engined aircraft to an in-line one. He was warned that throttle movements in an in-line-engined P-40 had to be made more slowly than the technique he had used in navy planes. I’m not an engineer, so I don’t know why this would be, but it might reflect an institutional preference in the navy for airplanes that could be controlled in certain ways.
Did the Corsair, Hellcat, Avenger and Helldiver share the same engine? If so, the ease of carrying spare parts for more than one type of airplane might have been an incentive.
I’m only prejudiced in favor of truth, beauty and stamping out the pernicious myth that the US rushed in practically singlehanded to save the world from Hitler.
The Rolls-Royce Merlin was also pretty good. At least it was reliable enough to haul P-51’s both ways on some pretty long missions. And it was probably the prettiest sounding engine ever built. Just listen to an Avro Lancaster with four of them if you don’t believe me.
I’m going to quote G. Gordon Liddy here, so take this with salt or whatever, but according to him, the radial engine wants to stay turning, even when something goes wrong with it (say a total loss of oil pressure), whereas a V or inline engine’s gonna die immediately.
David Simmons? I’d love your opinions on some of these engines please?
The Rolls Royce Merlin, as compared to the Packard built Merlin? Were there any opinions held by either you, or your fellow flyboys, as to which was the superior engine? Or were they generally perceived to be held in equally high regard? Also, man, that thing was a 27 litre V12 and yet it could spin to 3,000rpm. Holy Dooley, that’s an impressive thing considering the size of the pots which were moving up and down.
It’s a funny thing about V12’s - for some reason they have a very musical note without much need for mufflers - even in cars.
How did the big 18 cylinder radials sound in comparison? Rather non musical I’m assuming.
Did you ever get to fly any of the single seaters? Or were you mostly a bomber man? My understanding is that pilots from the era regarded the Mustang as the most “complete and capable” fighter of the era due to it’s combination of speed, good flying characteristics, and long range - but that those pilots who ALSO had the pleasure of flying a Spitfire (especially the early ultra light ones) well they described that plane as feeling as though it was “wrapped around you” and that the slightest thought resulted in a super sweet flying direction change.
How were the big bombers like to fly? Cumbersome? And I bet they were friggin noisy! Any hearing damage?
Look forward to hearing your responses! Thanks in advance.
I’m not Dave, but I saw an interview with the official Rolls Royce historian and he was quite appreciative of the quality of the Packard built engines (well, as appreciative as the official historian for Rolls Royce can be).
Personally, I want to know if Dave’s the post-war airline pilot who replied to a snippy Berlin air traffic controller’s question of “Haven’t you ever been to Berlin before?” with
I know it’s probably an UL, but it’s damned funny if you ask me.
I have no personal experience with the Merlin engine. However, those in P-51’s were all Packards I think and I’ve never heard any complaints about their performance or reliability. The P-51 originally was equipped with an Allison which was changed to the Rolls because of better high altitude performance. Must have had a better supercharger.
Yes, the P-51 was a fine airplane, but so was the ME-262. The problem with the 262 was that Hitler ordered that only a bomber version be built for use on the Eastern front. I know that the few 262 encounters in the West caused considerable apprehension among aircrews, and their bosses.
No airplane is really cumbersome. Lift and control forces are proportioned to the size of the plane. The difference are the amount of power available per pound of plane, the stability, and the fact that bombers are not stressed for large reversed accelerations so inverted flight is a definite no-no. Fighter aircraft are designed for maximum maneuverability and so are marginally stable. In fact, modern jet fighters are aerodynamically unstable, or right on the edge at normal speeds, and are kept stable by autopilots in those flight regimes. Bombers are more stable although not always. For example, the Martin B-26 had zero wing dihedral and thus no inherent stability in roll.
Those who think flying a fighter is glamorous should sit for 8 hours all alone in a cold cockpit, on oxygen, unable to use a toilet and flying a plane that must be flown at virtually all times and then tell me how they like it. I know that fighter pilots think it’s great, but then they are a bunch of nutty kids.
And no it wasn’t me. I had little interest in postwar flying.
You got it backwards. It was the Corsair that caused trouble for transitioning P-40 pilots. The reason was Horsepower and Torque. The Corsair had something like 3 times the horsepower of the P-40, and swung a huge 21 or 22 ft paddle-bladed prop. As a result, if you firewalled it at low speeds you could actually torque-roll the airplane right over onto its back. In addition, bringing the tail up at high power would create quite a bit of precession, which could pull the aircraft right off the runway. I’ve flown a Maule M5 taildragger with 230Hp, and even in that aircraft lifting the tail required application of lots of opposite rudder to keep things straight.
David Simmons said:
Bite your tongue! Don’t try landing a tricycle-geared airplane on the muskeg in Alaska. Or on an semi-improved sand strip on Guadalcanal. Tailwheel aircraft are lighter, faster, have more prop clearance, and require less maintenance than equivalent tricycle gear airplanes. Of course, there’s no question that they are unstable and prone to swapping ends (had a friend lose a gorgeous Stinson Reliant to a ground loop a few years ago), but there’s room in the aviation world for all configurations. How much weight would a nosegear for a Corsair added to the plane, when you add in the hydraulics, gear doors, actuators, backup systems, etc? What would that have done to bomb load, roll rate, Cg, etc? So you’ve got to S-turn on the ground. Small price to pay for big advantages.
Advantages to a Radial Engine:
Radials actually have many solid advantages over water-cooled inlines like the Merlin:
[ul]
[li]Reliability. This is a big one. No water jackets to crack. No coolant lines to get shot up. No radiator. Early water cooled engines had major reliability problems even without battle damage.[/li][li]Power to Weight Ratio. Radials reigned supreme. No reduction gearing, no complex cooling systems, and a short crankshaft meant that radials produced more power than water-cooled engines of the same weight. [/li][li]Max Power at Lower RPM. This is a big one. A P&W R2800 made 2,000 HP at 2,400 RPM. The Merlin V in the Spitfire and Mustang made 1,200 HP at 3,000 RPM. The lower RPM requirement meant you could turn a bigger, slower propeller, which is more efficient than turning a smaller propeller at higher speeds. You can put a bigger prop on a slower engine because the main limiting factor in prop size is keeping the tips out of the transonic region where drag builds rapidly. The combination of big props, big horsepower, and low RPM meant that the big radial fighters like the Corsair could kick the ass of their equivalent inline cousins in a climbing contest. A P-51D could climb at about 2,600 ft/min. An F4U-4 had a climb rate of 4,170ft/min, which is close to a P-38 which had two engines.[/li][li]Maintenance simplicity. A big factor in WWII where aircraft had to be repaired in the field.[/li][/ul]
The primary disadvantage with the radial was frontal area, which created a lot of drag in the air. Before WWII, airplanes were slow enough that this wasn’t a big factor, so the radial reigned supreme. Consequently, they were highly developed and refined by the time the war broke out. Water-cooled inlines were still in their infancy, getting their major development boost from the Schneider Cup seaplane races in the 1930’s.
The frontal drag was an issue, but the higher horsepower of the radial made up for lots of that - the P-47 was actually faster than the P-51 Mustang. But the tradeoff was fuel consumption, and where the P-51 came into its own was in efficiency, which is why it could escort bombers into Germany and back. As they used to say, “A P-47 can do what a P-51 can, but the P-51 can do it over Berlin”.
The reasons given above re: the original OP question are pretty much it. The USN decided fairly early that inline engines were not reliable enough for carrier aircraft (reliability being especially an issue when you can’t put the crate down in the nearest cow pasture if the engine fails), and decided to go all radial. The extra weight and complexity for servicing also were a factor, as was the general emphasis by American engine companies on radials over inlines (strongly influenced by the military preferences). They stuck to this decision even after better inline engines became available.
The Japanese also made the same choices, helped by the fact that they had difficulties in developing good inline engines. The Brits, who had a strongly developed inline engine industry, had fewer qualms about reliability and were more attracted to the higher power available from inlines (until the late WW2 and post-war period, the top inlines were significantly more powerful than the top radials), and had a number of inline-powered carrier aircraft.
I don’t think there is any doubt that for bush pilots a tricycle gear is a poor choice. However, the P-39 did operate out of some pretty scrubby place in North Africa and the Southwest Pacific, such as New Guinea.
The need was for sustained operations by a lot of planes with pilots that weren’t all that experienced in some pretty foul weather. So dirt runways were not all that common since they were covered with pierced steel landing mat as rapidly as possible. Mud, you know, which isn’t all that great for tail draggers either.
Sure. As did the P-38. I’ve got nothing against nosewheel aircraft, and every time I ever landed a taildragger the pucker factor was always a little higher than with a nosewheel airplane. But I had to fly my nosewheel-equipped Grumman AA1 out of a fairly rough grass field a few times, and with every little bump I thought the prop was going into the ground.
The US Navy did develop a carrier version of the P-39 Airacobra, under the designation Bell XFL-1 Airabonita. Modifications included relocating the radiators, adding an arrestor hook and making the aircraft a taildragger. Only one was built.
The british also used the Spitfire (Seafire in this case) and the Hurricane as carrier based aircraft, both inline engined.
A long way up…
Well, my understanding is that the P-51 wa a complete bitch to fly, specially while the rear fuel tank was full, since that moved the center of gravity waaay back; which ain´t the best place to be.
Nope. The Lockheed Constellation, like the B-29, had four Wright Cyclone R-3350 engines: eighteen cylinders in two rows.
On the sound of the radials, this page has a wav of a B-29 flyover (above the photo of the B-29), and this’n’ has one of a radial starting up. Not as pretty as the Merlin V12, but the roar of four R-3350s is not unpleasnt, from a proper distance (there was a Constellation flying circles over my house during the last airshow at the local airport).
One more thing, on the durability of radials: a show on the History Channel about the P-47 interviewed a pilot who had a few cylinders shot off of his engine by AA fire, and managed to fly it all the way back home, noticing the problem only because it was running a little rough.
