Packard had been building V12's for aircraft, marine, automobiles since before 1920. The Packard V12 used in small craft like torpedo boats was a 40 litre engine of Packard's own design. Don't confuse this with the Packard built Merlins. Totally different engines.Quote:
Originally Posted by ramblingboy42
Actually the Merlin was a very ordinary performer at altitude up until the Mk. 20 which was the first to use Stanley Hooker's two stage supercharger. This transformed performance above 20,000 feet. The turbo/supercharger system used on the Lockheed P38 needed a lot of development which it didn't get for a multitude of reasons. Allison were a relatively small company flat out on war production and didn't have the resources for development. Besides which the patents for the turbo system were owned by the USAAC who insisted Allison use them and actually supplied them to Allison after ordering them from GE. Given that the P38 had extraordinary ceiling and altitude performance and speed as was it would have been a real goer if the engine problems were sorted. The Allison and Merlin were the only liquid cooled engine used on US military aircraft in WW2. All others were aircooled radials.Quote:
Originally Posted by JDNSW
The major problem with the turbos was that they required special alloys that were simply not available in the necessary quantities. Allison was not the only company stressed by wartime production problems - at least they didn't have bombs coming through the factory roof like RR did. Everyone was pushed to the limit, and many companies were doing things they had never done before. To take a local example, during the war, there were about ten thousand Gipsy Major engines built in Australia - by GMH and Tasmanian Railways! Neither organisation had built aeroplane engines before, even small ones like these.Quote:
Originally Posted by Bigbjorn
The US did, as you say, largely use aircooled engines in WW2. This was mainly due to experience with the Liberty engine of WW1, which seems to have had major issues keeping water in. Both aircooled and liquid cooled engines were widely used by all the combatants in Europe, with top performers such as fighter aircraft using liquid cooled engines mainly because of their lower frontal area until fairly late in the war when the generally larger size of aircraft meant engine frontal area became less of an issue.
The US had an advantage in the aircooled engine in that a lot of development had continued in these in the two years before the country entered the war - once the war is on there is a strong pressure to stick with what you already have and develop that. A prime example is the Merlin. Developing 890hp in the Fairey Battle in 1936, in 1945, in the Hornet, it was producing over 2,000hp.
Aircooled engines were less able to be increased in power, a good example of a comparable power is the P&W R1830, which produced 800hp initially, but never exceeded 1350hp. It is a lot easier to increase the cooling in a liquid cooled engine!
Yes, Buick made several hundred thousand radial aircraft engines, Frigidaire made .50 machine guns in similar quantities after redesigning it to make it on their sheet metal machinery and by 1944 had cut the cost by more than half. Cadillac made tanks as did Chrysler. Ford made B24 bombers in the US and Merlins in England. Offenhauser who only made racing engines made fine tolerance hydraulic components for the Los Angeles aircraft factories having machining expertise second to none.Quote:
Originally Posted by JDNSW
The US Navy was opposed to liquid cooled engines. The navy considered radials more tolerant of battle damage. Their concern was getting pilots back on board the carrier. Industry could make planes much quicker than the navy could train carrier pilots.
The Allison intake system on the P38 gave inefficient and unequal mixture distribution and needed a full redesign and testing. Uneven distribution is a major problem on a high boost pressure charged engine. They also suffered detonation (pre-ignition) under high boost condition. The boost retard systems available then were not up to the job and needed more work. Problems arose when using the P38 as escorts in the temperatures encountered at high altitudes in the European winter. Turbos would heat and cool unevenly and crack casings, Intercoolers freeze up. No such problems in the Pacific theatre where the USAAC loved them and kept asking for more. The USAAC credited the P38 with destroying the land based Japanese air force. It could fly higher and faster than anything the Japs had. Allison didn't have the resources to do the development and were reluctant to do so on items patented by someone else.
This is a good read on the P-38.
Der Gabelschwanz Teufel - Assessing the Lockheed P-38 Lightning
The US Navy was definitely opposed to liquid cooled engines, but not so much because of the risk of battle damage as because of their experience with the Liberty engine. The airforce, not so much, probably because, as you point out, easier to build more planes than to train pilots, and while a pilot who has to bail out of a plane over land has a good chance of survival, this does not apply over ocean. And the pilot over land may well be able to make a forced landing.Quote:
Originally Posted by Bigbjorn
The Japanese had a serious problem with aeroplane engines during the war. While the Germans, English, Americans, and even Russians were able to successfully uprate their engines or design better ones and actually build them in useful numbers, it seems the Japanese were unable to do so. A good comparison is to look at the famous fighter aircraft of the war - Britain was using Spitfires at the start and finish, but the 1945 version was way ahead of the 1939 one, and they were also operating Typhoons, Hornets, Spiteful, that were not even thought of at the start of the war, in 1939 the best the US could do was the P-40, which was behind any of the European fighters in every respect, but by 1945 they had a whole range, including the P38, P51, and a number of others all undreamt of in 1939. Germany started the war with the Bf109, ended with the FW190 and Me262 (and the Bf109!). But Japan in 1939 had arguably the best shipboard fighter in the world in the A6M; it was still their front line aircraft in 1945, but had not only not improved in performance, but it was lower performance, as it had put on weight - but the new engine never went into production successfully. The big advantage the US had over everyone else was their industrial depth - as you say, car makers built planes - but they also built cars, trucks, jeeps etc. And, since this is a Landrover forum, worth pointing out that Rover built aeroplanes, aeroplane components, jet engines, and tank engines.
And let us not forget the debt owed to the fuel chemists in improving engine performance. In 1939, fuel was 80/87 octane at best, by 1945 front line aircraft were routinely using 115/145, and occasionally higher. Add this to improvements in supercharger, and this is where most of the increases in power came from (of course, the engine had to be strong enough mechanically and adequately cooled as well).
Here are some photos of a Packard V12 marine engine. These were taken at the Packard Museum in Dayton, Ohio. Well worth a visit if you are near. Some magnificent classic cars. It is in a former Packard dealership right in downtown DaytonAttachment 158229Attachment 158230Attachment 158231.Quote:
Originally Posted by Bigbjorn
The USAF National Museum is not far away. This needs several days if you are an aircraft fanatic. Carry your passport as you need to show it to get the tour of the restoration shop which is on a working air force base.
Here is another photo. This one has been restored and is in the Nethercutt Museum in Sylmar, Los Angeles. Another do not miss place if you are in LA.Attachment 158236
An Uncle worked on both Merlin and Packard Merlins during WW2. He once commented that you did not need to see the makers name plate to know which was which. His opinion was that although both were built to the same standards that those of one manufacturer were more exacting was evident to anyone who spent their time up to their elbows in them
Absolute nonsense. All were built to high standards. Merlins were built in Crewe, Derby, Glasgow by Rolls Royce, in Manchester by Ford , and in Detroit by Packard. Packard at one time couldn't keep up and subbied some production out to Continental. It was Ford and Packard that showed R-R how to mass produce high precision engine parts to be assembled by unskilled labour. Ford and Packard between them made slightly more than half of all Merlin production.Quote:
Originally Posted by 3toes
Sir Stanley Hooker wrote this in his autobiography "Not much of an engineer".
Stanley Hooker's autobiography, Not Much of an Engineer, deals mostly with his work on Rolls-Royce jet engines. But its section on Merlin development, the superchargers of which Hooker played a role in developing, is illuminating:
"In my enthusiasm, I considered that Rolls-Royce designs were the ne plus ultra, until the Ford Motor Co. in Britain was invited to manufacture the Merlin in the early days of the War. A number of Ford engineers arrived in Derby, and spent some months examining and familiarizing themselves with the drawings and manufacturing methods. One day their Chief Engineer appeared in (Merlin development head Cyril Lovesey's) office, which I was then sharing, and said, 'You know, we can't make the Merlin to these drawings.'
"I replied loftily, 'I suppose that is because the drawing tolerances are too difficult for you, and you can't achieve the accuracy.'
"'On the contrary,' he replied, 'the tolerances are far too wide for us. We make motor cars far more accurately than this. Every part on our car engines has to be interchangeable with the same part on any other engine, and hence all parts have to be made with extreme accuracy, far closer than you use. That is the only way we can achieve mass production.'"
Mass production, in the sense of interchangeable parts, only really entered the aeroplane engine world in WW2. Like other aero engine manufacturers, Rolls Royce built engines by fitting the manufactured parts, often by selective fit. It was the way it had always been done, and working to the very close tolerances needed for these engines without having to do 'fitting', was not justified for the small numbers of aero engines that were produced up till then. There simply were not very many aero engines built of any one design.
But motor manufacturers, or at least the (successful) mass market ones, had already crossed that bridge, some of them even before WW1. When these companies were asked (or told) to build aero engines, they had already leaned how to do this, and passed this on to the aero engine designers and original manufacturers.
Two other factors affected this ability - the need for improved production machinery, including some less obvious things; for example, building aero engines in Australia was only possible after the establishment of the National Standards Laboratory (now National Measurement Institute).
A less obvious difference in building these engines was the extent to which the designers had incorporated ease of manufacture in the design. And this is tied to how well the designers knew the production methods, and very likely led to a lot of changes in the Merlin, as well as the Allison over the war years.
