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<font face="Comic Sans MS">Well Robert you got me all excited
talking about standards. Temperature and metal size was so
important in machining to close tolerances. I started searching
on a parrallel standardization topic, that of screw threads and
fineally answered a question I've been wondering about for years.
The P51 mustang was a good airplane, but became a great airplane
when mated with the British Rolls Royce Merlin engine. I wondered
if Rolls Royce used Whitworth threads and if they did were the
Mustangs equiped with a engine with Whitworth threads? Well they
were!<br>
<br>
<small><font color="#333333">Scarfed from
<a class="moz-txt-link-freetext" href="http://www.enginehistory.org/british_fasteners.shtml">http://www.enginehistory.org/british_fasteners.shtml</a></font></small><br>
<br>
</font>Packard Built Merlins
<div style="background-color: #00FFFF"> <br>
<big><font face="Comic Sans MS">An often asked question is; “did
Packard replicate the British thread system when they built
Rolls-Royce Merlins under license during World War II?” The
answer is yes; all threads that were used on the Merlin were
accurately replicated by Packard. This would include BSW
(British Standard Whitworth), BSF (British Standard Fine), BSP
(British Standard Pipe) and BA (British Association). Having
said that, however, Packard Merlins used U.S. built Bendix
injection carburetors; PD-16 for single stage engines and
PD-18 for two stage engines, both of which used U.S. Unified
threads. British built Merlins employed S.U. carburetors using
Whitworth threads. The job facing Packard when they undertook
manufacture of the Merlin was daunting to say the least. It’s
bad enough having to build a complex product like the Merlin
but exacerbating the situation was the fact no tool maker in
the U.S. made Whitworth taps or dies. Therefore, Packard were
forced into making their own. Although this created a
significant hurdle to overcome, the effort was well worth it,
Packard and Rolls-Royce components were interchangeable.<br>
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Robert Seastrom wrote on 11/8/2015 11:37 AM:
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I suppose that we all largely take for granted the notion that 20c is "standard temperature" for most measurements. But how did that come to be anyway?
A friend recently sent me this: <a class="moz-txt-link-freetext" href="http://nvlpubs.nist.gov/nistpubs/jres/112/1/V112.N01.A01.pdf">http://nvlpubs.nist.gov/nistpubs/jres/112/1/V112.N01.A01.pdf</a> which may be of interest to the folks here.
-r
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