Shortround6
Major General
But the British wound up using car building techniques to build the Merlin. When Ford of England took up the task of running the shadow factory at Trafford Park they had to redo the drawings and tolerances.
This is from Wiki but agrees with most other sources;
"Having an abandoned factory in Trafford Park, Ford of Britain was approached about the possibility of converting it into an aircraft engine production unit by Herbert Austin, who was in charge of the shadow factory plan. Building work on a new factory was started in May 1940 on a 118-acre (48 ha) site, while Ford engineers went on a fact finding mission to Derby. Their chief engineer commented to Sir Stanley Hooker that the tolerances used were far too wide for them, and so the 20,000 drawings would need to be redrawn to Ford tolerance levels, which took over a year.[65] Ford's factory was built with two distinct sections to minimise potential bomb damage, it was completed in May 1941 and bombed in the same month. At first, the factory had difficulty in attracting suitable labour, and large numbers of women, youths and untrained men had to be taken on. Despite this, the first Merlin engine came off the production line one month later[66] and it was building the engine at a rate of 200 per week by 1943, at which point the joint factories were producing 18,000 Merlins per year.[27] Ford's investment in machinery and the redesign resulted in the 10,000 man-hours needed to produce a Merlin dropping to 2,727 in three years, while unit cost fell from £6,540 in June 1941 to £1,180 by the war's end. In his autobiography Not much of an Engineer, Sir Stanley Hooker states: "... once the great Ford factory at Manchester started production, Merlins came out like shelling peas. The percentage of engines rejected by the Air Ministry was zero. Not one engine of the 30,400 produced was rejected ...".[67] "
I do have copy of Sir Stanley Hookers autobiography and this is essentially in agreement with what that says. R-R could take parts built to the drawings with wider tolerances and either hand select or hand fit them into tight tolerance assemblies using skilled labor. Ford was used to making parts to tighter tolerances and then using semi-skilled labor to assemble units using completely interchangeable parts. The end result (finished engine) may not be that much different.
One of the men from Ford said (basically) they could not make tens of thousands of cars per year at cheap prices without completely interchangeable parts that required no hand fitting.
That may be the basic "automotive technique" but with a bit tighter tolerances and inspection. "Vees for Victory" claims 20% of the Allison work force were inspectors and gives numbers for the number of operations needed to make a Cadillac car engine connecting road and an Allison rod (Cadillac sub-contracted crankshafts, rods, camshafts and other parts for Allison). It was considerably more for the Aircraft rod.
Both engines were subject to upgrades in material and construction techniques as production continued. Allison started shotpeening the crankshaft at some point after starting production and by some point in 1942 was nitriding the crankshaft. Thses later crankshafts were much longer lived than the early ones. Bearing materials may have changed. Merlins introduced Crankshafts that feed oil from both ends and other detail improvements. Late war engines could last 2-3 times longer between overhauls than early war engines inspite of increased power output.
Merlins definitely had a better supercharger set up once Hooker started working on them and so had better high altitude performance but I don't think either engine had much of an advantage over the other otherwise, including quality of build. And quality of build changed during the war for both engines so if one was ahead for a few months it might swap back again later.
I don't believe I have said anything bad about the Merlin. I just don't think, supercharger aside, the Allison was inferior to the Merlin to nay large degree and certainly not for many of the reasons bandied about on the internet.
This is from Wiki but agrees with most other sources;
"Having an abandoned factory in Trafford Park, Ford of Britain was approached about the possibility of converting it into an aircraft engine production unit by Herbert Austin, who was in charge of the shadow factory plan. Building work on a new factory was started in May 1940 on a 118-acre (48 ha) site, while Ford engineers went on a fact finding mission to Derby. Their chief engineer commented to Sir Stanley Hooker that the tolerances used were far too wide for them, and so the 20,000 drawings would need to be redrawn to Ford tolerance levels, which took over a year.[65] Ford's factory was built with two distinct sections to minimise potential bomb damage, it was completed in May 1941 and bombed in the same month. At first, the factory had difficulty in attracting suitable labour, and large numbers of women, youths and untrained men had to be taken on. Despite this, the first Merlin engine came off the production line one month later[66] and it was building the engine at a rate of 200 per week by 1943, at which point the joint factories were producing 18,000 Merlins per year.[27] Ford's investment in machinery and the redesign resulted in the 10,000 man-hours needed to produce a Merlin dropping to 2,727 in three years, while unit cost fell from £6,540 in June 1941 to £1,180 by the war's end. In his autobiography Not much of an Engineer, Sir Stanley Hooker states: "... once the great Ford factory at Manchester started production, Merlins came out like shelling peas. The percentage of engines rejected by the Air Ministry was zero. Not one engine of the 30,400 produced was rejected ...".[67] "
I do have copy of Sir Stanley Hookers autobiography and this is essentially in agreement with what that says. R-R could take parts built to the drawings with wider tolerances and either hand select or hand fit them into tight tolerance assemblies using skilled labor. Ford was used to making parts to tighter tolerances and then using semi-skilled labor to assemble units using completely interchangeable parts. The end result (finished engine) may not be that much different.
One of the men from Ford said (basically) they could not make tens of thousands of cars per year at cheap prices without completely interchangeable parts that required no hand fitting.
That may be the basic "automotive technique" but with a bit tighter tolerances and inspection. "Vees for Victory" claims 20% of the Allison work force were inspectors and gives numbers for the number of operations needed to make a Cadillac car engine connecting road and an Allison rod (Cadillac sub-contracted crankshafts, rods, camshafts and other parts for Allison). It was considerably more for the Aircraft rod.
Both engines were subject to upgrades in material and construction techniques as production continued. Allison started shotpeening the crankshaft at some point after starting production and by some point in 1942 was nitriding the crankshaft. Thses later crankshafts were much longer lived than the early ones. Bearing materials may have changed. Merlins introduced Crankshafts that feed oil from both ends and other detail improvements. Late war engines could last 2-3 times longer between overhauls than early war engines inspite of increased power output.
Merlins definitely had a better supercharger set up once Hooker started working on them and so had better high altitude performance but I don't think either engine had much of an advantage over the other otherwise, including quality of build. And quality of build changed during the war for both engines so if one was ahead for a few months it might swap back again later.
I don't believe I have said anything bad about the Merlin. I just don't think, supercharger aside, the Allison was inferior to the Merlin to nay large degree and certainly not for many of the reasons bandied about on the internet.