[Milsurplus] Research Help Requested

[James Whartenby]

Here is a link to "A Short History of Reliability."  It should give you a feel for the issues.

https://kscddms.ksc.nasa.gov/Reliability/Documents/History_of_Reliability.pdf

As reliability was investigated, the idea of the AEG or Active Element Group was developed.  An AEG consists of one active element (tube, transistor, relay etc.) and the associated passive devices in the circuit.  Typically, there are 10 passives for every active element.  With the start of the Cold War, weapons systems became very complex, very fast.  The first designated weapons system was the B-47, the first jet bomber.

When the B-47 was designed, the transistor was still a laboratory curiosity.  Some of the avionics on board the B-47, like the Bombing and Navigation System, had upwards of 300 vacuum tubes and a MTBF measured in single digit hours.  No wonder everyone in the know was in a panic to improve reliability since a mission to bomb the USSR lasted several times the system MTBF.

So comparing the BC-348 and ART-13 to the liaison radio aboard the B-47 is apples to oranges.  The B-17 or B-24 had something like a 10 man crew and carried about 4 tons of bombs.  The B-47 had a three man crew and carried one H-bomb that equaled all of the ordinance used by all sides in all theaters of WW2.

Beyond the reliability of components and vacuum tubes, the local environment of the avionics black boxes also played an important role in reliability.  There is even evidence of the roughness of the taxiway, ramps and runway having a negative affect on avionics.  Things worked well at engine turn on but not when running up the engines for takeoff!
Jim


--------------------------------------------
On Mon, 8/28/17, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:

 Subject: Re: [Milsurplus] Research Help Requested
 To: "Ray Fantini" <RAFANTINI at salisbury.edu>
 Cc: Milsurplus at mailman.qth.net
 Date: Monday, August 28, 2017, 1:26 PM
 
 On 28 Aug 2017 at 18:06, Ray
 Fantini wrote:
 
 >
 What's the link?
 
 Here
 you go, Ray:
 
 https://ia600302.us.archive.org/9/items/ReliabilityFactorsForGroundElectronicEquipment/He
 nney1956ReliabiltyFactorsInGroundElectronicEquipment.pdf
 
 > Somehow those numbers
 don't sound realistic. 
 
 Well, **I** was certainly surprised, but when
 it was explained, then it made things much 
 more clear.
 
 > But that's just an
 > assumption on my part. Biased on antidotal
 evidence of looking at
 > decades of
 experience with things like BC-348 receivers that I have
 > never seen fail or BC-342 receivers that
 are capacitor failure prone
 > but only
 after thirty years or the one time endless supply of
 things
 > like EE-8 field telephones or
 almost all of the command family of
 >
 radios that the problems were always Ham modifications or
 hacking.
 
 The article talks
 about failures in the field, the problems of not having
 competent 
 repair-people, BIG problems in
 shipping, BIG problems in design, the fact that there was a
 
 HUGE supply of stuff which somewhat
 overrode the other problems, and made it less 
 obvious, etc.
 
 On a related note, surely you are aware of the
 HUGE problems there were with crystals 
 early in WWII?
 
 > Systems like the ARC-8 (BC-348/ART-13) or
 the ARC-3 radios served on
 > in some
 cases until the seventies
 
 Yes, but how much maintenance did they receive
 during that period? THAT is the question. 
 Our use of the mil gear is so very much easier
 on the equipment than what it was designed 
 for that in OUR uses it will last forever. Used
 in a very large, very noisy, vibro-massage 
 device at 30,000 feet and 30 below zero is an
 entirely different matter. Or being hammered 
 by big guns on a Navy ship. 
 
 > so I just have a hard
 time accepting
 > that more than half of
 what was produced was non reliable. But that's
 > just me, going on how all the stuff back
 in the old days that you got
 > surplus
 was packed in cardboard, foil and everything else can't
 wrap
 > my head around it. I do recall
 reading in the Green Books about how
 >
 lots of equipment was damaged in shipping due to just common
 stupidity
 > and a story on how much of
 the equipment shipped to a port in the
 >
 Pacific was destroyed because when it was packed for
 shipment in the
 > states the heavy stuff
 like generators were packed lowest and the
 > delicate stuff like radios were on top and
 at the destination the
 > longshoremen
 unloaded the radios first and then stacked the generators
 > on top but would assume that's a
 mistake you only make one or two
 >
 times.a 
 
 Different people,
 different incidences, too many to count.
 
 Read the article. It will make things clearer.
 It sure did for me. I was amazed.
 
 Ken W7EKB
 
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