WWII fighter powerplants: Navy vs. AAF

[Kevbo]

@ElvisL1ves

The later-model P-51’s had Packard Merlins instead of Allison V-1710’s, yes, but what other US planes had them?

Some Mustangs had Allisons alright, but not all Mustangs were P-51s. All the P-51s had Rolls Royce engines. The design was originally done for the RAF, who dubbed the plane the Mustang. These British Mustangs DID have Allisons in them, but the RAF never called them P-51s. P-51 was the designation of the next generations (quite a number including the “twin mustang” H variant) of the aircraft, sold to the US armed forces…who also retained the Mustang moniker of the brits. These were outfitted with Rolls Royce Merlin engines, though a few of the last ones got RR Griffins which made a bit more power than the Merlin.

So the English used the version with the American engine, and the Americans used the version with the English engines.

[TheLoadedDog]

@Rick

Don’t forget when comparing kill ratios between US planes and the A6M that the Zero did not have self sealing fuel tanks or armor for the pilot.
IOW, while highly maneuverable, were rather easy to shoot down.

Didn’t the Zero get some (inadequate) armor fitted towards the end of the war? I seem to recall something like that, along the lines of a cursory fitting of a sheet of not-very-thick-at-all metal behind the pilot’s seat.

[Cicero]

@Throatwarbler Mangrove

So? Is it your position that nimbleness counts for nothing? I could say the exact opposite was true up until 1942, precisely because the Zero was so nimble. What I’m saying is that the engine comparison you draw may be inadequate, because you are not comparing their use in similar sized aircraft.

Just slightly off topic- in relation to the MIG 15 and F 86:

Chuck Yeager once said (1), “The pilot with the most experience is going to whip your ass, no matter what you were flying- it’s that simple”. Yeager had just proven his point by beating a Lieutenant Colonel in two dogfights. In the first Yeager had the MiG 15 and the Colonel had the Sabre. In the second the pilots swapped aircraft. The result though was the same: Yeager stuck to the tail of the Colonel as if he was attached by glue.

[Johnny_L.A]

@DesertDog

I recall reading of a P-47 pilot over Europe… The Jug pilot scrunched behind his armor plated seat back and felt the plane shudder from a stream of hits…

This reminds me of a Bob Stevens cartoon. Frontal view of a pilot sitting in his P-47 cockpit. A 109 is behind him, and bullets are bouncing off the Jug. The pilot looks bored and thinks, ‘I suppose I could wait until he runs out of ammo…’

Another Bob Stevens cartoon depicts a Mustang pilot and a T-Bolt pilot in a pub. The angry T-Bolt pilot says [paraphrasing], ‘OK, your Mustang can outmaneuver my Jug. But I’ll be I can out-fall you!’

[Hypno-Toad]

@DesertDog

I recall reading of a P-47 pilot over Europe who’d been badly shot up and was limping home. He couldn’t maneuver well and his guns were jammed so he was praying he didn’t get spotted, but of course, a Bf 109 found him. The enemy pilot pulled alongside and looked at him a long moment, then dropped behind. The Jug pilot scrunched behind his armor plated seat back and felt the plane shudder from a stream of hits – to no effect.* The Bf came along side again, then dropped back for a second burst – still no kill. A third lookover and Our Hero, rather cheekily, gave a little wave. After another, rather shorter try and he was still flying. Pulling alongside, the German pilot – presumably out of ammunition – popped a salute and peeled off. The Thunderbolt made it back to England without further adventures, but it never flew again…

This event was in an episode of “Dogfights.”

[UncaStuart]

@Kevbo

Some Mustangs had Allisons alright, but not all Mustangs were P-51s. All the P-51s had Rolls Royce engines. The design was originally done for the RAF, who dubbed the plane the Mustang. These British Mustangs DID have Allisons in them, but the RAF never called them P-51s. P-51 was the designation of the next generations (quite a number including the “twin mustang” H variant) of the aircraft, sold to the US armed forces…who also retained the Mustang moniker of the brits.

The P-51A was Allison-engined. The P-51B was the first AAF variant with the Merlin.

TheP-51H was basically a total redesign, but was not called the Twin Mustang. That was reserved for the P-82.

[Knorf]

@DesertDog

I recall reading of a P-47 pilot over Europe who’d been badly shot up and was limping home. He couldn’t maneuver well and his guns were jammed so he was praying he didn’t get spotted, but of course, a Bf 109 found him. The enemy pilot pulled alongside and looked at him a long moment, then dropped behind. The Jug pilot scrunched behind his armor plated seat back and felt the plane shudder from a stream of hits – to no effect.* The Bf came along side again, then dropped back for a second burst – still no kill. A third lookover and Our Hero, rather cheekily, gave a little wave. After another, rather shorter try and he was still flying. Pulling alongside, the German pilot – presumably out of ammunition – popped a salute and peeled off. The Thunderbolt made it back to England without further adventures, but it never flew again.

This story is told in Robert S. Jonhson’s Thunderbolt , his story of flying P-47s in Europe. Johnson was the #2 ace in Europe during WWII, having scored 27 confirmed kills (with one additional probable).

His opponent on that day was apparently Egon Mayer, flying a Fw 190. Link.

[sqweels]

@Knorf

His opponent on that day was apparently Egon Mayer, flying a Fw 190.

And he was out of cannon ammo for his wing guns.

As for the OP, not having to carry coolant and maintain cooling systems made for one less thing for the Navy to worry about.

[ElvisL1ves]

@Bosda Di'Chi of Tricor

I recall that one class of formerly air-cooled engine aircraft was retrofuitted, but mixed it up with Corsair.

Got another for you. The Ju-88 was generally made with inline engines (in cylindrical cowlings), but there were some models with radials - apparently from late-war supply issues.

[Johnny_L.A]

@Can Handle the Truth

In the book Fighters 1914-1945, author Bill Gunston argues that the preponderance of liquid-cooled V (LCV) aviation engines in WWII fighters was due to the influence of the Schneider Trophy races, which evolved into contests of pure speed. Most, if not all, contenders in these races had LCV engines. These engines were favored by the racers because they made possible a more streamlined look than the “blunt-nosed” radial engine. Consequently, in the 1930’s the fastest planes in the world all had LCV’s, and this fact influenced the design of fighters. If a fighter was designed with a radial engine, it was usually because the company was unable to obtain the desired LCV’s due to all of them being used by a “more important” project: for example, the Fw-190 used a radial because the Me-109 production was using all the available LCV’s.

The book arrived today and I read the powerplant chapter. As you say, the choice seems to have been based on the Schneider Trophy racers. But it also seems to say that radials were better and that it just took some time for designers to learn how to put them into fighter airframes. It also mentioned that one reason the V-12s were powerful was that they had larger displacement than comparable radials.

[Raguleader]

@Knorf

This story is told in Robert S. Jonhson’s Thunderbolt , his story of flying P-47s in Europe. Johnson was the #2 ace in Europe during WWII, having scored 27 confirmed kills (with one additional probable).

His opponent on that day was apparently Egon Mayer, flying a Fw 190. Link.

It’s also told in The Mighty Eighth: The Air War in Europe as Told by the Men Who Fought It, by Gerald Astor, an overall excellent book based on interviews, letters, and journals written by airmen fighting in WWII.

[slaphead]

@Johnny L.A.

The book arrived today and I read the powerplant chapter. As you say, the choice seems to have been based on the Schneider Trophy racers. But it also seems to say that radials were better and that it just took some time for designers to learn how to put them into fighter airframes. It also mentioned that one reason the V-12s were powerful was that they had larger displacement than comparable radials.

I thought that in the early days one of the characteristics of liquid-cooled engines was a much better power/displacement ratio? That, together with the slimmer profile, would suggest they were massively advantageous for racing. But towards the end of the piston-engine fighter era radials were becoming ever more powerful than liquid-cooled V-12s. If you look at things like the Typhoon/Tempest/Fury evolution, they just kept cramming more cylinders and displacement under the hood.

Building a V-18 engine was an engineering challenge too far,and the X-24 type designs were also failures (Vulture, Sabre), so until turbines came along radial was the only way to go for significantly more power. And if you are going radial, you may as well go air-cooled.

[DesertDog]

@Knorf

This story is told in Robert S. Jonhson’s Thunderbolt , his story of flying P-47s in Europe. Johnson was the #2 ace in Europe during WWII, having scored 27 confirmed kills (with one additional probable).

His opponent on that day was apparently Egon Mayer, flying a Fw 190. Link.

That’s it! I was wracking my brain trying to remember the name of the book when I was posting. I can even remember the cover of the paperback, now that I know it.

@sqweels

And he was out of cannon ammo for his wing guns.

I stand corrected on both counts. I must have retconned the opponent to a Bf.

[Johnny_L.A]

@slaphead

I thought that in the early days one of the characteristics of liquid-cooled engines was a much better power/displacement ratio? That, together with the slimmer profile, would suggest they were massively advantageous for racing. But towards the end of the piston-engine fighter era radials were becoming ever more powerful than liquid-cooled V-12s. If you look at things like the Typhoon/Tempest/Fury evolution, they just kept cramming more cylinders and displacement under the hood.

From the book:

[quote]
Even today the powerful emotional link between the Schneider Trophy success, the Merlin engine and the Hurricane and Spitfire makes it difficult to accept the true facts. The superiority of such engines as the Merlin lay partly in the intense effort applied to their ancestors in the years of racing, partly in the fact that they were simply bigger than most radials (and thus were more powerful) and, above all, in the fact that it took so long for designers to learn how to install a radial in a high-speed aircraft… Each month, in 1929-39, the power of radial engines went up, the cooling was improved and the drag reduced.
It also says that the radial engines were lighter, cheaper to make and easier to maintain. Also,

Its finned cylinders, much hotter in relation to the surrounding air than a water radiator, got rid of excess heat perfectly even in the hottest desert climate. Unlike the water-cooled engine, there was nothing to freeze in Arctic winter conditions, and no water circuit to need warming up.

(Note that the author is talking about water cooling, as opposed to ethylene glycol.) It goes on to say that the shorter, more compact radial was better suited to a fighter because it improved maneuverability and handling.

Back to the OP:

After extensive competitive trials the US Navy declaired in 1928 it would buy no more water-cooled aircraft, and even discarded or re-engined almost new machines with such engines.