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True, but...

Posted by bdk on Fri Apr 25, 2003 06:23:38 PM

In reply top Re: Engineering question (DB engines) posted by jcw on Fri Apr 25, 2003 04:14:40 PM

While what you say is entirely true, what specific parts are actually in short supply?

In the case of the DB, I know the magnesium prop reduction gearcase is a problem. I think a new one was cast for David Price's 109. Is there truly a shortage of Merlin or DB cranks- or is it the crankcase that is in short supply, or what?

I would expect that for the Merlins, the shortage would be with wear parts for overhauls like pistons, bearings, and cylinder sleeves, not cases. Cranks can be ground undersize, or in some cases chromed back to standard size.

With the DB series, the shortage would probably be due to corrosion. I've seen lots of DB recovery pictures that appeared to have nicely preserved internal parts, but the exposed aluminum and magnesium alloy parts looked like soda crackers...

: :i can give you one problem. RR can't even make the crack
: for a Merlin nor a DB when asked. $$$ was not the problem.
: . the problem is the tooling. it takes a BIG steam drop f
: orge to make them. under the old design that's what it wo
: uld take. to do it with modern technology would requre a C
: OMPLETE re-design of the eng for modern techniques. the en
: g revolves around the crank so when you change that, the s
: nowball effect will drive a complete re-design which will
: place you in a position of how much can you absorb to desi
: gn, build, test snd re-test after many failures until you
: get it to work. it took very large companies, with governm
: ent unlimited backing, during a war, to make that happen i
: n a reasonable amount of time in the past. don't forget th
: at the die that was used in the drop forge only produced a
: bout 50 cranks and then you needed to machine a new one..

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