[Milsurplus] Research Help Requested

[Ray Fantini]

Thanks for an excellent explanation and link on the subject of reliability and military electronics.  The exchange of theories, ideas and opinions are what this list server can do at its best, but only if the party making those statements can demonstrate those facts in a clear and direct way and with evidence to support their argument.

Ray F/KA3EKH




-----Original Message-----
From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of James Whartenby
Sent: Monday, August 28, 2017 3:56 PM
To: Milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Research Help Requested

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.