I was surprised, I think it was one of Jeff Ethel's vids of the P-51. (Maybe) Said the Merlin was not a smooth engine, some vibration. Not like radials that were very smooth when they were running. I always thought a V-12 would be very smooth and a radial had a LOT of vibration... maybe due to the exhaust note and the drama of getting it started. Surprised.
Jim- The guys in Korea wished they had P-47s instead of P-51s when doing CAS. Not unusual for a P-47 to come back with a couple of jugs missing from the R2800 and 16 still firing. One shot in the radiator or any cooling line and the P-51 was toast. Robert Johnson's story of a German pilot running out of ammo trying to shoot him down from dead astern is quite a tale.
+1 But *Nothing* has quite the sound of a Merlin. Drop it into a Spitfire or even the much overlooked Hurricane, and I still get goose bumps. Awesome! Thanks for sharing. As you say, 'when engineers ruled the world'. Cheers, Ian
P-47 is one of my favorites. Not real pretty and kind of fat but what a tough deadly machine. The story I heard when they made landfall in Britain for the first time, the comments were, "Nice bomber".
Another of my favorites was the DO335.(Regardless of it's heritage.) Big and very fast. Too late for the war and with the onset of jets, nearly obsolete. Image Unavailable, Please Login
One helluva airplane! Not a dogfighter but but didn't have to be. A boom an' zoom hitter. Would have been deadly for the bombers with all the fire power and speed that it had.
I have heard this many times during WW2 that you had to work pretty hard to kill a P-47 and/or the R2800. Recently I was educated on the frailties of the Merlin vs. the Allison. Sparky knows.
Bob- Affirmative, the Allisons were very tough and the only thing holding them back was a two stage supercharger that was more efficient like the Merlins used. The turbochargers on the P-38 allowed it to have a much better rate of climb than a P-51 at just about any altitude. One reason the F-5 Lightnings did not worry much about being intercepted, they just outclimbed whatever was chasing them. Excepting the ME-262, or course. Once at altitude they froze to death, but you have to make a few sacrifices.
Only at the end did Allison finally get the supercharging right, with the engines used on most of the F-82s. (I understand that the Merlins became unavailable when Rolls Royce pulled the plug on Packard's contract after the end of the war!)
I heard all those stories from my old late friend Larry Blumer. He went through a lot of fights and a lot of P-38's, 5 to be exact. All of his mounts were named "Scrap Iron", Scrap Iron 1,2,3,4,and 5. His story is part of my second attempt to write a book. Other P-38 drivers that I have known all mentioned the lack of cockpit heat and freezing at altitude.
Jim- That is funny because Packard made a bunch of reliability improvements on the Packard-Merlin. Those F-82 Allison engines were at least as good as the Merlins. All the P-51Hs, from which the P/F-82 was developed, had Merlins, but they cut off production as the war came to a close.
From an engineering point of view, what is the thought process between choosing and building an air cooled radial, over a liquid cooled V12's or what ever the configuration. Is it a case of the engine manufacturers saying this is what we have, build your airframe around it, or the airframe folks saying we need this type of engine go build us one ?? What are the relative merits and draw backs of each , aside the obvious drag of the radial and the loss of coolant in a merlin ?? I think the chaps that did the sleeve valve Naiper-Sabre engines where drunk
As an aside, theu US Navy would not use liquid-cooled engines, especially those that might end up shipboard. Since so many Navy planes were Grumman (and vice-versa), I cannot think of a single liquid-cooled Grumman plane.
A properly cowled and "spinnered" radial is as drag free as an in line engine. If we take a look at some of the more successful speedsters you will find that many of them are radial powered. Good power to weight ratio and the lack of a drag producing radiator and the associated systems are big reasons to chose a radial. Reliability is another. They are easily supercharged , turbo or mechanically. Think of Greenimyer's (spl) Grumman F8F, the F7F, FW-190 and all the pre-war racers at Cleveland...Roscoe Turner's Special, Wedell Williams,etc. All with powerful, reliable, and well cowled radials.
Both types had been in use since before WW-I, along with the rotary heavily used in WW-I that disappeared soon after the war. The rotary was replaced with the more advanced radial that reused its oil. As such, development continued in parallel and total power to weights remained similar. So you had something like contemporary biplane P-6Es powered with a DOHC V12, and P-12s powered with a radial. Actual drag from the radial engine was not significantly more than for the water cooled engines when you took the radiators and oil coolers into consideration. As mentioned, power to weights were similar when you added in the water, radiators, etc. The UK tended to like water cooled V or H engines, the US was split about evenly, although all our medium and heavy bombers were radial powered and the UK used inlines in their bomber fleet. The Germans also used both types. The radials tended to be complicated, but robust, while the inline engines were relatively simple, with the coolant vulnerability. So it was whatever a manufacturer could offer that had the hp you needed and aircraft were designed around the engines. Makes you wonder, though, when you consider the Jug and the Bearcat used the same basic engine. Fluids were a pain on ships, so the US tended to use radials there, but the UK used inlines on the Seafire and other navalized aircraft that did not come from the US (Wildcats, Corsairs, etc). Just two good solutions to the same problem. Note most inlines were supercharged and most radials were turbocharged, but there were exceptions, like the P-38.
I'll chime in with what little knowledge I have. "Is it a case of the engine manufacturers saying this is what we have, build your airframe around it?" Well, in the case of the P-47, yes. "The Jug," so nicknamed because many felt it looked like a milk jug laid on its side, was literally designed by creating an airframe around a Pratt & Whitney R-2800 Double Wasp turbosupercharged engine and its associated ductwork. It made for a huge plane, but it also made one that was as close to "damned near indestructible" as a WWII era fighter could be.
Bob, The British did a lot of actual comparison work on "in flight drag" between the two different engine configurations on the prototypes of the Hawker "Tempest", then the "lightened Tempest" which became the "Fury", then "Sea Fury". Three different engines were evaluated in flight, of broadly comparable power, bolted on the same airframe: the Rolls-Royce Griffon (V-12); the Napier Sabre (H-24); and the Bristol "Centaurus" (Radial, sleeve valve, double row, 18 cylinders). Three different radiator configurations were also tested for the "inlines": the "chin" radiator for the Sabre, then leading edge wing radiators, then annular radiators. All appendages (radiators, etc) taken into account, the drag difference in total was evaluated at a 7% penalty for the radial Centaurus over the best in-line installation. It is known that the British re-evaluated their preference for the in-line engine for fighters after having examined the first Focke-Wulf 190 to have landed in Britain, the one of Arnim Faber, lost over the Channel. The Brits were quite suprised to discover how cleverly the exhausts were integrated and routed on that airplane, and the exhaust solution found on the "Fury/Sea Fury" for the Centaurus is a direct inspiration from the FW 190. Rgds
Thanks, very interesting info. I believe that the exhaust routing on the F8F is very similar to the FW-190, also.
On the FW-190, the Luftwaffe stuck with the radial for those aircraft designed for ground attack, like the A-8, but transitioned to inline V12s for the later interceptor versions like the FW-190D and TA-152 models.
There is a FW-109D in the Paul Allen's collection here on Paine Field. They won't fly it and I don't think that they run the Junkers "Jumo" either. It is an awesome looking big airplane. 1800hp and 2100 with boost, high altitude broad bladed prop, and lots of big guns. Bad news for the bombers. Iv'e read where the BMW radial was engine of choice because all the DB's were allocated to the ME 109 series. Iv'e seen his FW-190A fly with the original BMW radial and it's a sight to see...and hear.
Terry, True, but on the other hand, it is slightly more complicated: it was not inherent to the radial design technically, but it came mainly from the choices made by the german RLM before the war in the destination for the three main engines in production, which were the Daimler-Benz 601, the Jumo 211 and the BMW 139. The Focke-Wulf 190 was conceived by Kurt Tank with a radial engine (initially the BMW 139, then the 801) for two reasons: - Tank had observed that the radial engine was lighter than the in-line, and that the US Navy was using it with success on its fighters. He was convinced that a good fighter could be designed with a radial engine, provided that extreme care was given to streamlining the cowling and directing cooling air very efficiently. - Tank was not very close to the circles of powers of the IIIrd Reich, and feared that he would not be allowed to design a fighter aircraft, as the Luftwaffe already has one in the Bf109; but he thought that his project could have a chance because it would not use the DB601E, which was in short supply, being used on the Bf109 and Bf110 already. Tank knew full well that the use of the BMW engine would not allow the aircraft to be operated as an high altitude fighter, but saw this as a bonus, because his fighter would not be seen as a direct competitor to the Bf109. This came indirectly from the radial configuration of the engine: not from a technical point of view or from its lack of performance, but because that the radial was thought to be unsuited to a fighter, because of its size and frontal area. Most fighters in Europe at the time were using in-line engine, so no-one considered that time lost on trying to adapt a radial to a fighter would be justified, and furthermore there was no need for this, as the Bf109 was considered adequate. So the BMW engine (initially the 139, which derives from the P&W Hornet, then the 801) was originally intended by the german aero-engine production system for utility, transport and bomber aircrafts; as such, there was no need for developing its high-altitude performance, so it was given a very simple, rather basic supercharger (even if the device used to control the engine, the Kommandogerät, was extraordinary and very advanced). It is this supercharger design, rather the fact that it was a radial, that always limited this engine to low/medium altitudes. The 801 was produced in large numbers (almost 30.000) and the work on improving the supercharger design, or adapting the engine to turbo-supercharging was attempted, but never given a high priority, because other engines already adapted to high altitudes were available at the time. The Junkers inverted in-line V12 engine at the end of the thirties was the Jumo 211 (JUMO is an acronym from JUnkers MOtoren) which was not seen by the RLM as very suitable for a fighter, as it was slightly heavier than the Daimler Benz DB601, partly due to the fact that it was not using a pressurized cooling system, contrary to the Daimler Benz, so crucially the 211 was losing cooling efficiency at higher altitudes. Which explain that the JUMO 211 was mainly “relegated” to bombers (JU-87, 88, etc…it was the aero engine built in the largest numbers by Germany, by the way: 68.000 produced). Junkers were never very happy with this and began to work on adapting a pressurized cooling system to a variant of the 211 (which was successful) and, on the other hand, to fully capitalize on the benefits of it, in so far as the pressurized cooling was more efficient, used less liquid, etc…they designed a new, smaller, lighter engine block, for an engine of the same capacity than the 211 but able to run at higher RPM, which became the JUMO 213. It was a direct concurrent to the DB603. When the priority of the Jagdwaffe turned to interception of the bombers over the Reich, at 20.000 feet both the FW190 and the Bf109 were still satisfying against B-17s and B-24s; but if other new bomber types were to be able to fly higher, a new fighter more suited to high-altitude would be needed. For high altitude, two engines were already available, both in-lines, because these were intended as high altitude engines from the beginning: the DB603 and the Junkers JUMO 213. Focke-Wulf was working on a high-altitude variant of the 190; with the DB603, it was the FW190C; the JUMO 213 became available at this time, was tried in the 190D, which was the variant eventually built. When they designed a fighter for even higher altitudes, the Ta 152, this used again both the Daimler-Benz engine (in the Ta-152 “V21” prototype, which became the Ta 152C in production) and the Junkers engine (Ta-152 “V20” prototype then Ta-152H in production). It is not the radial design of the BMW 801 that explains that it was not used on the high-altitude variant of the FW 190, but choices made before the war to reserve the BMW radial to transport, utility and bomber aircrafts. No work was done on developing a high altitude variant from inception; had BMW been able to evolve the design of the very basic supercharger chosen because the engine would not have to fly at high altitude as “not suited for fighters” (what Kurt Tank demonstrated as not true), a high-altitude variant could have been developed. But other engines, specifically designed from the start for high altitude, were already available; these were “in line” engines, but mainly for choices made before the war, corresponding to the line of thought at the time. Rgds
Regarding those "big guns"...isn't it quite ironic to think that three very efficient western 30mm cannons of the fities/sixties/seventies were direct development of the same german 30mm cannon, the Mauser MG 213C? It did not have time to enter production, but the french DEFA 551/552/553 (which has shot down quite a number of MiGs) the british ADEN and the US M39 are direct development of this Mauser. The French DEFA and the british ADEN are so close to the original design that they used the same ammunition. Rgds
If my memory serves me well (I don't have the time to search my aero engine library right now) the sleve-valve engine was partly the results of a paper, and some conferences, given by the great british authority on Aero Engines Harry Ricardo, who, in 1927, was convinced that reaching powers above 1500 hp would only be possible by either increasing capacity or gaining RPM, and that the weight of the valve-train and pushrods on "poppet engines" would never allow these high rotational speeds needed for more power. So people began to work on different systems than the traditional valve gear, which gave us the sleeve valve. See here: https://en.wikipedia.org/wiki/Harry_Ricardo There has been about the same line of thoughts for Formula One engines during the eighties with a french engineer called Guy Nègre, who was convinced that ultimate power of the F1 engines was limited by the weight of the valve springs and devised a very interesting system, the "rotary distribution" on a 3,5 W12; put it very simply, valves and camshafts were replaced by a hollow cylinder turning at the same speed of the camshaft, but with a serie of holes and ports. His engine was a success, it was even tried on track, but was killed when Renault came with the pneumatic valve, eleiminating valve springs, and allowing very high RPM. http://users.telenet.be/sarahgrimonprez/didier/aircars/html/Guy%20NegreENG.html Rgds
That position has been taken over and over throughout the history of reciprocating internal combustion engines and has been disproven as many times.
The Germans have had many ideas in the area of weapons emulated and copied by others over the years. The Mauser bolt action rifle is considered the granddaddy of all bolt rifles. The STG44 is the granddaddy of all automatic light infantry rifles. The German 88mm cannon used in nearly every application possible was considered an unusually efficient cartridge much the same as our own .50 caliber Browning but I am unaware of what it may have led to.
