That is an amazing piece of complicated precision mechanics! I love it!
Just curious, what is the general market value of one of those in good working condition?
John
Sent from my ATT Bell Rotary Dial Phone
Hi Doug,
I misread your email... When you said "aircraft clock" my eyes immediately looked over to mine which sits on my desk beside my computer sceen and thought you had the same one (how could I have mistaken Waltham with Hamilton?...)!
The clock I have is a Hamilton H-37500:
http://www.hamiltonchronicles.com/2014/09/wwii-hamilton-h-37500-elapsed-time-clock.html
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By far the coolest and most complicated Hamilton clock I've ever laid hands or eyes on is the WWII-era H-37500 Elapsed Time Clock. This specialized clock was designed ...
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Peter
From: Doug & Terri <dnt [at] dock.net>
Sent: September 26, 2016 11:13 PM
To: 'Peter Rychel'
Cc: 'The FerrariList'
Subject: RE: [Ferrari] No Ferrari Content - Waltham Aircraft Clocks.
Wow Peter – that sounds like a VERY complicated time piece. Mine is very simple: 12 hour face, one 60 minute stop watch, 12 Arabic numbers.
Easy to read.
DOUG
One less thing to rely on electricity. Back in those days, all instrumentation were mechanical, so that would have included the clock as well.
I haven't taken mine completely apart, but I've had the case back off and the componentry are mighty substantial. Must be to survive radical temperature swings, high frequency vibration, etc. Also,
it's one of the most complicated clocks fitted to an aircraft, with 24 hour main dial, date, elapsed time (with a night/day display indicator because that sub dial is 12 hr!), hack seconds, and chronograph - all requiring a lot of "juice" from the mainspring
(almost a couple of nickels thick!).
Mine still has a (faded) US Navy stamp on the back...
Very cool clock. Probably an A-13A model. Standard issue for military aircraft for a long time.
As a watch enthusiast (ask me about my Citizen Electronic running at 43.200 beats per hour) I can safely say that an automatic version would more complicated to engineer for an aviation environment
and to mil spec. That and the rotor would be rather hard pressed to keep turning to wind the mainspring. Can you say barrel roll?
Anyway, as for the 8 day power reserve for the mainspring, that makes sense from an operational standpoint. You had to set it before each flight so it makes sense to have it running for longer periods
of time between missions. Less fiddling with it when a pilot got in the aircraft to do their pre-flight checks.
I suspect that while they were fairly accurate per se, they did need to meet certain performance standards. So, another reason for the 8 day power reserve is that a mainspring powered clock (or watch)
will lose accuracy during the last portion of the power reserve -- in this case the last 24 to 48 hours.
Get it serviced and mount it. great conversation piece.
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