Originally Posted by
DozyWannabe
I have a very strong belief that the avionics of your beloved bird owed a great deal to the advances made on the Trident
I don't think so....
I'd be the last one to restart the "Smiths/Elliotts war" of the time on a forum and a topic like this, a subject so much better discussed today over a pint at the local!
But it's a subject worth discussing, and I'll be only too pleased to see other input!
For me, there are two key differences between Trident and Concorde.
The first one is, that Smiths went for the "triplex" solution, with three computers continously "talking to each other", and checking that all three were "reading from the same song sheet".
If they didn't agree, no autoland.
Elliott, who did the VC10, and then Concorde (with SFENA), went for the alternative "duplex monitored" solution, with two computers, where each of the two was effectively two computers in one, with a "command" and a "monitor" channel being compared continously.
If the two halves didn't agree... end of story : the computer would disconnect and hand over to the other one, which up to then would have been a "hot" standby.
Otherwise, the two computers basically did not "talk to each other".
BITE (built-in test) was used to assure that both computers were still serviceable just before committing to an autoland, thereby reducing the 'time at risk' of a common failure to a couple of minutes, and the resulting risk of such a failure to "highly improbable".
The other difference was simply a matter of age.
The Trident system came into being before the arrival of integrated circuits.
Now, I've never had a real opportunity to dive into the Trident electronics, but going by other systems from the same period, I would expect it to be full of things like magnetic amplifiers, transistor-based operational amplifiers, and transistor and relay type logic.
Concorde happened just at the time of the arrival of the first integrated operational amplifiers and the first integrated logic circuits.
At that time, integrated circuit development was going so fast, that the avionics on the prototypes, the preproduction aircraft and the production aircraft basically ended up using three succesive
generations of integrated circuits..... (for the conoscienti here... think 165, 709 and LM101 for the opamps, and RTL, DTL and TTL for the logic).
So, to make sure we agree... the Trident and Concorde both, certainly profited hugely from the pioneering work of the BLEU, and the experiments with the Lear system on the Caravelle.
But, IMO, they diverged afterwards.
CJ