Thread: Merlins

Originally Posted by Brian Hjelm

I can assure you that all Merlins used British threads. Personal experience. It was going to be too much trouble to re-draw thousands of engineering drawings to convert.

Mate, sorry but there was a bit of a mix up. initially the yanks build motors with fittings supplied by the poms, then the poms couldn’t keep up so they stated to make there own imperial stuff. once the US army got involved they wanted all there stuff. NB UNC and UNF are American threads not English

Originally Posted by Brian Hjelm

, as well as causing untold confusion and maintenance problems as soon there would have been a mix and match situation in the field requiring duplication of spare parts. I still have taps and dies made in the USA in WWII in British systems supplied to the allies for production and maintenance of aero engines. They used seldom encountered items like 5/32, 7/32, 9/32 BSF left and right hand. Left hand BA, and other monstrosities..

As squadrons were formed and equipped or taken of the line and re equipped with aircraft that came sequentially off the line. this was a deliberate move as different motors and air frames from different factories did differ quite a bit.
replacement aircraft came from where ever.

Originally Posted by Brian Hjelm

,
Ford told Rolls-Royce that they could not mass produce the engine using RR's tolerances. "Ha", said RR, "you rough motor car types can't work to our high standards". "No", replied Henry's men, "your tolerances are too wide for mass production. We require identical parts that can be assembled by unskilled labour, not selective assembly by skilled fitters matching parts by micrometers." So the tolerances had to be re-jigged and Ford's Manchester plant built by the British government at a cost of millions went into production. ..

a nice bit of 1952 American propaganda, Fords Manchester plant was nationalised in 1940 after Mr ford made his Pro Nazi comments ( as polished in October 1939) ford didn’t get ownership of there plant back until 51,
Millions of pounds, yes that what it costs to convert a car factory to an aircraft factory.

Originally Posted by Brian Hjelm

Righto, Ben, what,where, who, when, and where did you find the photo?

Gar Wood

Also interesting:
channel4.com - science - speed machines

Perhaps Wood's greatest design was the Miss America X, called a "madman's dream" Powered by four 1800-horsepower, 12-cylinder Packard engines.

The boat smashed the world record, the first to do over 2 miles a minute: at 124.915 mph. It's a speed that, 64 years later, remains a respectable time for the Gold Cup race on the Detroit River.

Originally Posted by clean32

Mate, sorry but there was a bit of a mix up. initially the yanks build motors with fittings supplied by the poms, then the poms couldn’t keep up so they stated to make there own imperial stuff. once the US army got involved they wanted all there stuff. NB UNC and UNF are American threads not English



As squadrons were formed and equipped or taken of the line and re equipped with aircraft that came sequentially off the line. this was a deliberate move as different motors and air frames from different factories did differ quite a bit.
replacement aircraft came from where ever.


a nice bit of 1952 American propaganda, Fords Manchester plant was nationalised in 1940 after Mr ford made his Pro Nazi comments ( as polished in October 1939) ford didn’t get ownership of there plant back until 51,
Millions of pounds, yes that what it costs to convert a car factory to an aircraft factory.

You need to read "The Magic of a Name, The Rolls- Royce Story The first 40 Years" by Peter Pugh; "Not much of an Engineer" by Stanley Hooker; "British Aviation - The Ominous Skies 1935-39" by Harald Penrose.

A.R.Smith, the managing director of Ford, received the necessary authority from the Treasury and decided to build an entirely new factory at Trafford Park, Manchester. Penrose wrote "The result was a shop with tools tailored to the Merlin's design, though less capable of being switched to different engines, fundamentally more productive of Merlins than the Rolls-Royce line in Derby, and making a cheaper engine of no less quality."

Hooker stated "Ford would have to redraw all of the Merlin drawings to their own standards, and this they did, It took a year or so, but was an enormous success, because, once the great Ford factory at Manchester started production, Merlins came out like shelling peas at the rate of 400 a week. And very good engines they were too, yet never have I seen mention of this massive contribution which the British Ford company made to the build-up of our air forces."

Pugh records Merlin production as:- Derby 32,377. Crewe 26,065. Glasgow 23,647. Ford Manchester 30,428. Packard and Continental 55,523. In 1944 Packard had reached a peak production level of 2,000 a month. So Rolls-Royce made half the Merlins, and Ford, Packard, and Continental made the other half. Lord Hives conceded that Rolls-Royce never had a hope of meeting the demand with their production facilities and methods.

Originally Posted by JDNSW

That is something I did not know about them (the threads I mean). I wonder if that is part of the heritage of those engines? As you may know, the first DH Moth used an Airdisco engine, which was made by mating four cylinders from a Renault V8 to a new crankcase. The Gipsy 1 engine was designed as a successor to this when the supply of disposal Renault engines ran out, so it is likely to have used metric threads as well, seeing the conversion and the Gipsy had the same designer, Major Frank Halford.

Of course you realise that small fasteners on the engines are certain to be BA - which has Whitworth heads but metric dimensions and threads (but a different thread form)?

John

you got it, frogy metric motor, pommy spanners. Airframes were all imperial. The motors didn’t change until the Queen 6. You will notice on the up right motors the angular sump plate, this became level just before they flipped it over.
BA came from DH just like the “font times new roman” I think ??

I have the R series cam profile some where but I don’t have the piston dimensions

Originally Posted by clean32

you got it, frogy metric motor, pommy spanners. Airframes were all imperial. The motors didn’t change until the Queen 6. You will notice on the up right motors the angular sump plate, this became level just before they flipped it over.
BA came from DH just like the “font times new roman” I think ??

I have the R series cam profile some where but I don’t have the piston dimensions

BA was pretty much the standard for small diameters for anything with any pretence of precision in the British Empire from about 1900 up to about 1950, when it started to be replaced by UNF. BSF was occasionally used for small fasteners, and of course for rough work Whitworth. But my 1970 2A still has a lot of BA in the small fasteners!

(My experience of DH engines is limited to the Gipsy Major, and then only from the throttle end, not the spanner end)

John

BA was adopted by the British Association for the Advancement of Science about 1900, to be used for electrical, instrument, and clock work. It was adapted from a Swiss thread, the Thoury thread, and the Association started considering it about 1884. It is of 47 1/2 degree form and uses metric dimensions and a 0.9 factor in progression down from 0BA, pitch = 0.9 designating number. 0BA is identical to M6 x 1.0 and will interchange with 1/4" BSF or 1/4" BSB (which two are identical). The British Standard of 1951 only covers 0BA to 16BA although sizes down to 26BA are listed in some publications. BA was declared obsolescent after the metric system was officially adopted as the primary system of weights and measure in the UK.

Its use today is pretty well restricted to repairers, restorers, and model engineers. Suttons still list a range of BA taps and dies in their catalogue but whether they still make them, or are selling old stock is a moot point. Bruce Gardner, B.S.F. Bolts, in Melbourne has a great stock of BA taps and dies.

Originally Posted by Brian Hjelm

BA was adopted by the British Association for the Advancement of Science about 1900, to be used for electrical, instrument, and clock work. .. .. .. .. ... ...

When I was a kid, dad had a jar of assorted small nuts and bolts. They never seemed to fit any other bolts or nuts. They may have been WWII RAAF as he was an armourer during the war.

Maybe they were BA threads from radios and such things.

That would explain why they never matched anything else wouldn't it?

Originally Posted by vnx205

When I was a kid, dad had a jar of assorted small nuts and bolts. They never seemed to fit any other bolts or nuts. They may have been WWII RAAF as he was an armourer during the war.

Maybe they were BA threads from radios and such things.

That would explain why they never matched anything else wouldn't it?

If of that vintage and under 1/4", it is most likely they were BA. 3/16" was the smallest BSF size, and BSW went down to 3/32" which was in use until quite recently in Yale type tumbler locks made in Australia.