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Concorde question

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Concorde question

Old 25th Aug 2010, 20:52
  #121 (permalink)  
 
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ChristiaanJ

Ah now, those boards are actually very good looking boards. I particularly like the PROM board and although I know about the programming of those, it is only at third hand. I certainly had to install many of those PROMS that had been specially 'burned' in Milwaukee, to overcome a particular problem.

I'm a bit embarrassed about missing that multi pin socket on the AICU board. I somehow thought it was a specific function chip or a development test socket. Some of those used to appear and remained on some of our boards.

I'm not surprised about the massive cost of replacing certain boards in the later years. Some of those components would have been made of unobtainium long before the millenium. And I just noticed DozyWannabe's question about core memory. I guess it would have been core, because the 8Kb memory boards I spoke about, from the early CT Scanners, were Data General core memory, with a cycle time of 800usec. Although with four way interleaving, we could get that down to the read cycle time of 200usec!!

I freely admit I am staggered at how capable were Concorde's electronics - indeed how capable was the whole aeroplane - despite their rather ..... fundamental nature. My respect for everyone involved in the project increases with every post to this thread.

Roger.
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Old 25th Aug 2010, 21:17
  #122 (permalink)  
 
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Originally Posted by DozyWannabe View Post
Any magnetic core memory in any of those systems?
I can't be positive about the INS (inertial nav system).
The prototypes used a SAGEM/Ferranti system, replaced by a Litton system on the preprods, then Delco on the production aircraft.
There may have been magnetic core in the prototype INS.

As to the AICS (air intakes) and AFCS (automatic flight control), the answer is a definite NO. The AICUs used PROMs (fuse type, not EPROM) and the AFCS was entirely analog.

Some of the systems were even more 'antique'...

The ADC (air data computer) for instance was still largely electro-mechanical.

And those nifty NAV and COMM frequency selectors, that always stand out on cockpit pictures... no electronics at all, just a set of wafer switches, and about thirty wires linking them to the transmitters/receivers.

CJ
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Old 25th Aug 2010, 22:04
  #123 (permalink)  
 
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Originally Posted by Landroger View Post
I'm a bit embarrassed about missing that multi pin socket on the AICU board. I somehow thought it was a specific function chip or a development test socket. Some of those used to appear and remained on some of our boards.
The PROM board is from an AICU, the other board is from an AFCS computer.
Could be Autostab, Lateral Autopilot or Trim, since they all used exactly the same technology, board size, etc.
Looking at the board, I think it's 'Lat A/P' but I can't be certain.
No excuse needed about missing the "central connector" !
It was really a "one-off" feature, invented by Bendix, and abandoned afterwards. I'm not even sure the early A300B AFCS computers, that used much of the Concorde technology, still had them.

I just noticed DozyWannabe's question about core memory. I guess it would have been core...
See my post on the subject. I doubt there was any core memory at all in the production aircraft.

CJ
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Old 25th Aug 2010, 23:07
  #124 (permalink)  
 
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Brit312
It's so great to have a Flight Engineer's input into this fascinating thread. Your write up on the complexities of managing the fuel system was something else; the best such description I've ever read. I'm still wetting myself with your story about the E/O coming out of the loo with his trolleys around his ankles after a surge. (Not you I hope ).
The original air intake that was in use for the first few years of airline operation was as you know far more prone to surging than the later modified intake with the thinned and lowered bottom lip, which was far more stable and forgiving. Not only was the 'new' intake more stable, a new leading edge fitted to the rear ramp as part of the same modification, at a stroke cured the very serious ramp vibration issue, that was causing intake structural problems at lower supersonic Mach numbers. The most impressive change of all was a fuel saving of around 1.5 Tonnes per Atlantic crossing, with even bigger improvements in cooler temperatures. A major software change obviously accompanied this modification.

ChristiaanJ
The one I know about is the ADC/DAC board (analog-digital and digital-analog converter board). The supply of either ADCs or DACs ran out literaly worldwide, and the board had to be redesigned, requalified and recertified with more recent components, and a new batch manufactured. The cost, for the replacement of that board alone, came to about 3 million euros

YEP! I remember now, the ADC/DAC board definitely WAS one of the candidates that were modified.
I think you will find the tale about AICUs being removed after museum delivery flights was more urban myth. The only units that I can remember being removed or relocated were the ground power protection unit, the TCAS processors and the radar transceivers. (BA had retrofitted their aircraft with a superb Bendix system a few years earlier, and the same units (with windshear detection re-enabled) are used on other aircraft types).
As far as ferrite cores are concerned, asked by DozyWannabe, the original Delco C1VAC INS fitted to the BA Concorde aircraft did utilise ferrite cores. These were replaced with CMOS EPROMs when a modification was carried out in the early 90's, in which a navigation database was fitted to the units. The fuel consumed and total fuel remaining indicators definitely used a ferrite core memory. These electronic displays used an internal memory in case of power interrupts. As far as AFCS goes, can you check your records? Although, as you say, a completely analog system (with the exception of the ITEM test computers) I seem to remember that the Safety Flight Control Computer used a ferrite core for the flying control strain gauge null memory. I could be wrong here, but I can't remember any other NVM in use at the time.

Galaxy Flyer
I'll leave it to one of my pilot (or F/E) friends to answer this one it that's OK.

Dude

Last edited by M2dude; 25th Aug 2010 at 23:20.
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Old 26th Aug 2010, 00:04
  #125 (permalink)  
 
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Thank you very much for that information guys. I guess I was trying to work out how the processing work was done, and I suppose from the answers given that other than the INS, it must have been worked out directly on the hardware in realtime. Obviously this was in the decades before von Neumann architecture became ubiquitous, which is why I find the subject so fascinating being a computer scientist (of sorts) myself!

This thread is officially awesome.
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Old 26th Aug 2010, 01:36
  #126 (permalink)  
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Thanks for the reply in regard to operating in TRUE Bellerephon.




At my Airline I have only seen this procedure used before on Polar Routes. I had theorized the reason this was done on the Concorde was because you were crossing Isogonic Lines so rapidly this would minimise heading changes.



So much for my theory !




On another subject entirely was smoking permitted in the Cockpit ?
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Old 26th Aug 2010, 07:48
  #127 (permalink)  
 
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Brit312 at 19.39 yesterday has given us a clue.
Surges
3rd paragraph.
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Old 26th Aug 2010, 09:23
  #128 (permalink)  
 
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take-off performance

Galaxy flyer -

TO perf calcs were basically sinilar to a susonic type, which involved a tabulation for each runway in a manual and an A4 proforma.

It was no more complex than a 'Classic' 747, but with a slightly different emphasis - e.g. all take-offs at full, reheated thrust, calculation of fuel transfer or burn off during taxy to achieve TOCG, calculation of timings and thrust setting for runway-specific noise abatement procedures, calculation of theta 2, and planned fuel flow and P7 to set in the take-off monitor (A system designed to aid, but not substitute, the decision of the FE as to whether TO thrust had been achieved, as well as auto selection of contingency power if a failure was detected).

You'd also determine whether a single reheat failure was acceptable that day - the little '3' or '4' bug at the lower left of the engine instruments was set as a visual reminder.

Not sure what you mean by Vzf? No flaps on this machine, so no change. May be a difference of nomenclature. Since there is no defined stalling speed for a delta (by conventional standards we lifted off about 60kts below 'stalling speed') Vzrc was substitued. This is the speed at which full thrust would result in a zero rate of climb. On three engines, this was the basis of the perf calculation, but we also calculated 2-eng Vzrc's gear up and gear down. IIRC they would come out at about 250kts/300kts.

On a transatlantic sector you would do all this and the speeds would invariably be within 5 kts of 160/190/220kts. (V1,Vr,V2)......

In the end we had a little handheld computer which would perform take off calcs, but to be honest it was only a minute more effort to carry out a manual calc.
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Old 26th Aug 2010, 11:43
  #129 (permalink)  
 
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Going back to expansion and paint. With the aircraft expanding approx 6 inches and a temp change up to 127`c, I guess a special kind of paint; able to withstand such adverse conditions; must have been used? When deciding on the paint specification was any consideration given to the overall weight of the paint?
Did the repeated expansion and contraction cycle have a detremental effect on the ulitamate life of the airframe?
I read somewhere that on the last supersonic flight of each BA Concorde, the flight engineer placed his cap into the gap between his panel and the cockpit bulkhead thus leaving it there for ever more. A nice story if true.
Once again thanks
Nick
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Old 26th Aug 2010, 12:55
  #130 (permalink)  
 
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EXWOK

Excuse me, Vzrc was exactly what I meant. I remember reading it in the Concorde CDG report and wondered if it figured into daily per calcs or was it a more technical

If you could depart with 3 reheats, I guess it wasn't a problem with the transition to supersonic flight? What I find amazing is the F-22 goes on about super cruise but here was a plane designed over 40 years that routinely super cruised.

GF
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Old 26th Aug 2010, 13:27
  #131 (permalink)  
 
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Originally Posted by M2dude View Post
As far as AFCS goes, can you check your records?
LOL. That should teach me to check my sources before putting finger to keyboard !
Most of my personal memories date from my Fairford years (1969 - 1974), so there may be the odd gap.....

CJ

Last edited by ChristiaanJ; 26th Aug 2010 at 13:52. Reason: typo
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Old 26th Aug 2010, 15:43
  #132 (permalink)  
 
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Originally Posted by Brit312 View Post
Surges were not an uncommon or common event on Concorde, but when they happened - as they usually affected both engines on that side - the aircraft would lurch /yaw and everybody on board would know about it...
It was determined in a very early stage, that an engine surge or engine failure at supersonic speed would produce a very abrupt, inacceptable, and possibly dangerous, amount of yaw.

So the prototypes were equipped with "autorudder" computers. They used pressure sensors in the engines to detect engine failures, and they would then kick in a "pre-dosed" amount of rudder, that would then be "washed-out" gradually while the pilot dealt with the issue and added rudder trim.

They were manufactured by SFENA, and since I was their flight test support at Fairford, they became automatically my "babies".

The computers (analog, big boxes, the same size as the autopilots or air intake computers) were extremely reliable (we had only two passive faults during the entire flying career of 002).
Unfortunately the same could not be said of the pressure sensors, and since it was always easier to "pull" a computer than a pressure sensor, we found a computer on the bench every few weeks, which then had to be taken through a full test spec and sent back with "no fault found", before anybody was willing to look at the sensors.

Luckily a better solution was found, using a lateral accelerometer, and from the preprod aircraft onwards, each big separate autorudder computer was replaced by a single board tucked away in the autostab computer.

Since the function was always "on", there was no separate autorudder engage switch. Many years later, I discovered that several airline Concorde pilots did not even know the function existed....

CJ
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Old 27th Aug 2010, 03:59
  #133 (permalink)  
 
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Nick Thomas
[QUOTE]Going back to expansion and paint. With the aircraft expanding approx 6 inches and a temp change up to 127`c, I guess a special kind of paint; able to withstand such adverse conditions; must have been used? When deciding on the paint specification was any consideration given to the overall weight of the paint?[/QUOTE
Can't remember much about paint spec's, but a lot of experimentation/trial and error was carried out with different paints until the right one was found. I remember when G-BOAD was delivered, that copiuous sheets of paint had peeled off in flight. Finally a superb polyurithane paint was found that did the trick perfectly.
Did the repeated expansion and contraction cycle have a detremental effect on the ulitamate life of the airframe?
Yes Nick, the life of the airframe was limited by the number of supersonic cycles, however modifications carried out extended the life of the airframe significantly. (and more were planned).
And the 'hat in the gap' stories are quite true.

ChristiaanJ
Many years later, I discovered that several airline Concorde pilots did not even know the function existed....

This was the real beauty of the autostab' on all 3 axis; you could just safely take it all for granted. The Mach 2 engine out case was a classic, as not only would the aircraft yaw towards the dead engine but there was an adverse roll input, where the wing on the same side would LIFT due to the excess intake air for the failed automatically being 'dumped' through the now open spill door. If for any reason the aircraft HAD been under manual rather than autopilot control, then life without autostab would be rather uncomfortable to say the least. And putting further Concorde's achievements in terms of stability; the world's only previous large delta winged Mach 2 aircraft, the B58 Hustler, had the slightly awkward feature in the case of an outer engine failure at Mach 2, in that the yaw forces were sufficient to tear the fin off. This happened on more than one occasion during service life of the Hustler, but engine failure (or far more likely a deliberate precautionary shut-down) although hardly a non-event in the case of Concorde, it was routinely dealt with without drama or danger.

Dude
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Old 27th Aug 2010, 04:26
  #134 (permalink)  
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During the early years of Concorde testing and Airline service I had read it was used as a 'target' for practice interceptions by the RAF.



Is there any truth to this and does anyone know the profiles that were flown ?
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Old 27th Aug 2010, 11:56
  #135 (permalink)  
 
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I understand that before the first flights the test pilots had many sessions in the Concorde simulator. I have always wondered how before the first flight they decided to programme the flight enverlope into the simulator; especially as Concorde was so different to other jet transports?
I guess that as more information was gained during flight testing; that this was programmed into the simulator and therefore made it a more suitable machine for airline crew training.
Thanks
Nick
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Old 27th Aug 2010, 13:46
  #136 (permalink)  
 
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Originally Posted by Nick Thomas View Post
I understand that before the first flights the test pilots had many sessions in the Concorde simulator. I have always wondered how before the first flight they decided to programme the flight enverlope into the simulator; especially as Concorde was so different to other jet transports?
From the thousands of hours of windtunnel tests, test flying with aircraft like the Mirage IV, HP 115, BAC221, etc. etc. they already had a pretty close idea of how the aircraft was going to fly.
IIRC, André Turcat remarked after the first flight of 001 it flew pretty well like the simulator, or if anything somewhat better!

I guess that as more information was gained during flight testing; that this was programmed into the simulator and therefore made it a more suitable machine for airline crew training.
There were two development simulators, one at Toulouse and one at Filton, that were used by the test pilots and by the engineers. These were "tweaked" whenever more data became availble before the first flights, and then updated with flight test data.
For airline crew training, two new simulators were built in the early seventies, again one in Toulouse (later moved to CDG) and one in Filton.
In the best Concorde style, they were designed and built by two different firms....

I don't believe anything of the development simulators has survived.
As you will know, the "cab" of the British Airways Filton simulator was salvaged and taken to Brooklands, where it's now slowly being brought back to life.
The Air France simulator at CDG, minus motion system and video display, was taken back to Toulouse, where it's slowly being restored, to go on display in the planned Museum at Toulouse.

CJ
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Old 27th Aug 2010, 14:55
  #137 (permalink)  
 
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stilton
During the early years of Concorde testing and Airline service I had read it was used as a 'target' for practice interceptions by the RAF.
Really a question for my pilot friends, BUT.. I do recall that several years ago an RAF Tornado F3 requested permission to try a practice intercept on a JFK bound aircraft coming up to the accel' point... ATC relayed the request to the crew who had no objections, provided tha the rules of the air were obeyed, the ATC conversation went something like this.... 'OK, the Tornado is 15 miles astern of you.'. (at this point the burners are lit for the transonic acceleration).. ' he's 14 miles astern of you... 15..16....17...20... you can gues the rest, the F3 gave up in embarassment.

Dude
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Old 27th Aug 2010, 15:35
  #138 (permalink)  
 
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YouTube - Concorde breaking the sound barrier

I feel the need to post this clip.
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Old 27th Aug 2010, 16:56
  #139 (permalink)  
 
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Concorde intercept

It was a Lightning that intercepted Concorde from behind:

English Electric Lightning Site - Story of the Month

I was in the Air Training Corps in Bristol in the late 80s and flew in the Chipmunks based at Filton. Used to see the spare Concorde sitting there outside the hangar. My father worked at BAe so we would go to the open day and see Concorde do her stuff there.

And a question of my own - I've heard that the engines were pretty powerful even at ground idle, so powerful that if all 4 were running then a tug would not be able to push her back. Any truth to this? Were just 2 started, pushback and then start the remainder? Also heard that the pilots had to watch the brake temps whilst taxiing out to takeoff - was this also due to the power?
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Old 27th Aug 2010, 18:42
  #140 (permalink)  
 
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Yes we always started just the two inboard engines prior to push back and the outers when the push back was complete. This was for a number of reasons, but I do seem to remember it was not unheard of to break the tow bar shear pin on the initial push, so the less power the better

Remember that Concorde had no APU and no across the ship ducting for stating engines, therefore prior to push an air start unit was plugged into each pair of engines and the inboard engines would be started. This allowed, after push back, air from each inboard engine to be used to start it's outboard engine.

The other good reason for starting the inboards prior to push was that with no APU the cabin temp would rise quite quickly [specially in places like Bahrain in summer] and never mind the passengers
comfort, but some of M2dude and ChristiaanJ fancy electronic equipment was very temp sensitive , especially those intake control units down the rear galley. With Two engines running we could use their bleed air to at least try and hold the cabin air temp during the push back

When we first started LHR-IAD flights[ prior to thin lip///54% and other mods which improved our range] some thought was given to towing the aircraft to the taxi way near the end of the runway before starting engines so as to save fuel. I do not remember this actually ever being done though.

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