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-   -   Concorde question (https://www.pprune.org/tech-log/423988-concorde-question.html)

a330pilotcanada 11th Aug 2017 01:22

Good Evening Stilton, M-2 Dude and others.
I am having a nostalgia evening as 20 years ago today I had a flight in G-BOAC from CYYZ to “no-where”.
Actually, it was down to New York out over the ocean for around 30 minutes at FL 550 and Mach 2. For one in the “industry” it was a real treat to be able to have a flight in such an iconic aircraft.
Things I will always remember going out of “reheat” (a more elegant description then afterburner) after noise abatement from being pushed back into one’s seat to being momentarily weightless, the brilliance of the sky at FL 550, the cabin windows being hot at Mach 2 and seeing the gap between the flight engineers panel and the bulk head at Mach 2 due to the aircraft heating. I could go on about the engineering, observing the crew coordination from the cockpit visit (sadly pre-9/11) and there is a certain story about how our group sweet talked our way into the first-class lounge in YYZ and drained all the bubbly British Airways had in the fridge that day but…….
Reading the thread on this aircraft has been fascinating and thank you to all that has contributed to this wonderful story a sincere thank you.

Shem Malmquist 19th Aug 2017 21:16

I have a different question. Does anyone know what happened to the engines on Concorde? I know the airframes are about, but all seem to be sans engines.

Shaggy Sheep Driver 28th Aug 2017 20:54

I think they mostly still have their engines, except AD in NY. Our AC at Manchester certainly does.

EXWOK 29th Aug 2017 10:57

AB had them removed for balance reasons, given that it has no interior.

Shaggy Sheep Driver 29th Aug 2017 13:15

Would the lack of an interior make that much difference? Museum Concordes have no fuel in the forward tanks (or, of course, any tanks), and are therefore in danger of becoming 'tail sitters'. Our AC at Manchester has (I'm told) ballast loaded in the forward fuselage to prevent that happening.

EXWOK 30th Aug 2017 12:13

It must make a fair difference: On average, much of the 'interior' is ahead of the CG and remember AB has no cockpit, which is a fair chunk of weight a long way forward,

I vaguely recall that AB was filled up with old 'High Life' magazines initially.

tdracer 30th Aug 2017 13:20

If memory serves, the Concorde at the Seattle Museum of Flight has engines (or at least something that looks like engines).
It also has an interior and flight deck - visitors are allowed to walk through the passenger portion of the aircraft (can't comment on the completeness of the flight deck since there is a big chunk of Plexiglas preventing close inspection).

Thridle Op Des 29th Sep 2017 12:03

Every time I taxi past 'AB in Heathrow I really feel sorry that somehow it hasn't become a centrepiece for one of the terminals, I half expected T5 to have it hanging off the ceiling. Are there any plans to bring it in from the inclement UK weather or is this an issue of elf n safety? It would be great if it were moved, if only not to distract me from heading up a non-code F taxiway.

grumpyoldman 22nd Oct 2017 20:32

AICU its boards and the interconnect wiring
 

Originally Posted by ChristiaanJ (Post 5892328)
Mine is one of the 202 development units, and 'knitting' is too kind... 'kludge' describes it better. I'll post a photo, if you like.
That myth was amplified substantially by BA removing those "secret" AICUs from the aircraft after the final delivery flights.
The way I understood the story was that they tried to collect as many reasonably reliable spare AICUs for the last few delivery flights, so as not to have to suddenly cancel a flight.
The AICU was right at the top of the list of "unscheduled removals". IIRC the tea maker was second...
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.
Somebody passed me a photo taken at Casablanca of a table full of AICUs waiting to be programmed... of course every software mod had to be programmed into all eight computers!
"... 'burning' each individual logic gate with a 9v battery." I believe you, thousands wouldn't... Didn't you have at least some sort of programming unit?
I went through a similar exercise around 1976, but at that time at least we had a programming "suitcase", that let you copy the original in RAM, modifiy bit-by-bit with a keyboard, then 'burn' the PROM (or EPROM, by then) 'automatically'. Still took half the night....

Funny in a way how these things have stuck in our memories... But then, yes, Concorde was unique.
I've said this elsewhere, but I don't mind repeating it... in those days, there were two programmes to be part of. One was Apollo, the other was Concorde. And I've had the chance to be part of one of them.

Well, I can claim some input to this Control Unit. The adc/dac was in fact AICU 1. I designed the PCB at BAC Electronic and Space Systems Div. in Bristol in 1971/72 as I remember. Both the A to D and D to A modules on the board were made by Analogue Devices in the states. There was an array of DG103 FET Switches as i recall. The circuit design engineer and the electronic packaging engineer and I had a few rethinks about component placement on this board. As I recall , AICU1 thru 5 were all control and processing boards. AICU6 thru 9 were memory , harris h512 PROMS mounted on heatsinks which were bonded to the PCBs and all mounted in their own sockets.
The inter board wiring was random, no harness arrangement other than for power supply. Cross talk was even considered by the design engineers then. Wire wrapped in 30awg OFHC single core cables.
I could go on about a lot of things used in the system as it was also my job to keep a record of all the components and which board they were used on. This also applied to the Sensor Unit, The Test Unit, The Management Control Panel. We were busy Bees in the DO for a few years on AICS. Happy Days

MurphyWasRight 28th Oct 2017 22:23


Originally Posted by grumpyoldman (Post 9933310)
The inter board wiring was random, no harness arrangement other than for power supply. Cross talk was even considered by the design engineers then. Wire wrapped in 30awg OFHC single core cables.
Days

( guessing you meant "Cross talk was not even considered"

The inter board (backplane I surmise) random wiring may be what allowed it to work.

"Way back when" I used wire wrap proto boards (socket for each IC) and found out the hard way that neatly bundled routing, Manhattan no direct cross country, greatly increased crosstalk compared to random 'rats nest' routing.

I once made everything start working by dropping a single ferrite bead over the clock driver pin (before adding the wires) to slow edge rate enough to damp reflections.
This was with a 66Mhz clock which is the upper limit for wire wrap.

Rush2112 29th Oct 2017 06:37


Originally Posted by Thridle Op Des (Post 9907733)
Every time I taxi past 'AB in Heathrow I really feel sorry that somehow it hasn't become a centrepiece for one of the terminals, I half expected T5 to have it hanging off the ceiling. Are there any plans to bring it in from the inclement UK weather or is this an issue of elf n safety? It would be great if it were moved, if only not to distract me from heading up a non-code F taxiway.

It's a great disappointment on the odd occasion I go through LHR to see it mouldering away half-forgotten like that. It's also disappointing when you arrive at the airport to see an EK model on the roundabout. Surely BA could afford to put something there? I cannot imagine any other country that would have someone else's flag carrier advertising at their main airport.

Casper 29th Nov 2017 09:00

https://youtu.be/fqOcYhzWUZY

I am ignorant of Concorde operations. I am an aircraft accident investigator, however, after many years of PIC international operations.

With respect to the above site, I'd be most grateful if the following points were to be confirmed in regard to AF4590:
* A spacer was not installed on the LH undercarriage
* The a/c was above its MAUW and outside its C of G limitations
* The take off was commenced with a downwind component
* The T/O run was commenced over tarmac still under repair
* No runway inspection was conducted, as required before any Concorde T/O
* No extra protection to fuel tanks had been provided, as had been done by BA
* The FE completed engine fire and engine shutdown without consultation with PIC

If the above is true, then the accident was unavoidable and I am astounded that the French authorities had the gall (Gaul) to blame Continental Airlines for FOD that should have been detected had the runway inspection been conducted as mandated. Shame!

atakacs 29th Nov 2017 20:16


Originally Posted by Casper (Post 9972671)
https://youtu.be/fqOcYhzWUZY

I am ignorant of Concorde operations.

Welcome to France...

condor17 29th Nov 2017 20:34

TD Racer , Had the privilege of bringing home to LHR from SEA the engineers who de-commisioned her . Was able to make them and their other halves comfortable as a thank you . Some had worked on Conc. for the whole of her BA career , and were retiring with her .
No mention of removing engines whilst chatting with them . However after decades of keeping her running , it was sacrilege for them to drain all fluids , cut pipes ; allowing air /moisture into hydraulic / fuel / oil lines . Disconnecting all electrics , cutting through many wiring looms , removing sections . They were told to make impossible to renovate back to flying condition .
On her delivery flight , via Toronto IIRC . The Canadians graciously allowed her to take a Northerly route over the Tundra with NO speed restictions . It all happened at the last minute , and the last sector had 30 , or was it 70 ? empty seats . A lost opportunity .

Shaggy Sheep Driver 29th Nov 2017 21:17

Casper, I'm not aware of any fuel tank protection by either BA or AF prior to the accident.

Overweight & aft GC was due too much fuel as well as captain authorising baggage to be loaded (in the rear baggage cabin) when the aeroplane was already about 5 tons overweight.

Something else germane to the accident was that the fuel tanks were overfilled leaving no airspace to absorb any shock waves on the basis this extra fuel would be burned off during taxi, but the change of runway (to a downwind one) meant a much shorter taxy so it wasn't burned off and the FE didn't ask for a delay while it got burned off. They just 'went'.

Worse - realising they had a rearward CG, fuel was being transferred from tank 11 (in the tail) to the wing tanks DURING THE TAKE OFF ROLL. an absolute no-no in Conc ops. The idea being as fuel was burned off from the wing tanks and replaced by fuel from tank 11, the CG would move foreward.

The result was the wing tanks were always overfull even though they were supplying fuel to the engines, so when one tank was hit by a big piece of tyre the shock waves travelled up through the fuel, bounced off the top surface of the tank, having found no gap of compressible air to absorb the overpressure, and travelled back down and burst the tank floor from inside.

CliveL 30th Nov 2017 09:27

Casper

You might find it useful to read the BEA accident report (in English) f-sc000725a which has all the information you are looking for

nicholas_c 10th Dec 2017 14:16


Originally Posted by a330pilotcanada (Post 9858539)
Good Evening Stilton, M-2 Dude and others.
I am having a nostalgia evening as 20 years ago today I had a flight in G-BOAC from CYYZ to “no-where”.
Actually, it was down to New York out over the ocean for around 30 minutes at FL 550 and Mach 2. For one in the “industry” it was a real treat to be able to have a flight in such an iconic aircraft.
Things I will always remember going out of “reheat” (a more elegant description then afterburner) after noise abatement from being pushed back into one’s seat to being momentarily weightless, the brilliance of the sky at FL 550, the cabin windows being hot at Mach 2 and seeing the gap between the flight engineers panel and the bulk head at Mach 2 due to the aircraft heating. I could go on about the engineering, observing the crew coordination from the cockpit visit (sadly pre-9/11) and there is a certain story about how our group sweet talked our way into the first-class lounge in YYZ and drained all the bubbly British Airways had in the fridge that day but…….
Reading the thread on this aircraft has been fascinating and thank you to all that has contributed to this wonderful story a sincere thank you.

I hope you will be interested in the following:- many years ago, when BA192 was a Concorde LHR-JFK, I asked if I could sit in the jump seat for take off. The captain agreed (maybe becuae I'm an engineer), and off we went. Pretty fun stuff. I was still up there when the reheat was re-engaged for the M 0.95 and up, and the captain said "we have a slight over temperature reading in engine #?, so I need to throttle back slightly" [it was almost a nervous tick I had noticed on this and previous flights that between reheat re-engagement and the final descent into JFK, the person flying pushed the throttles every few minutes - though omitting engine #? in this case]

Anyway the captain then says "never mind, we'll be in JFK 5 minutes early because of the "issue" - you can stay up for the whole flight if you can explain why".

After some serious cogitation, I sussed it out - any body else want a crack at it - and why wasn't an attractive option?

Lancman 12th Dec 2017 17:05

I understand from that excellent interview that refuelling automatically cut off at about 83% of full tanks for safety reasons: to provide an air space that would absorb any shock wave travelling through the fuel caused by the impact of a foreign object striking the tank. What I don't understand is why there was a facility provided to over-ride this protection, and under what circumstances it was authorised.

CliveL 13th Dec 2017 09:56

@Lancman

Not so on several counts

1. The phenomenon of structural damage arising from internal pressure waves in fuel tanks was unknown when Concorde was designed. Consequently the design made no specific provision for it.
2. 17% ullage is ludicrous on an aircraft for which fuel capacity is of vital importance. The correct value for tank 5 on Concorde is 6%.
3. Tank 5 was filled to 94% capacity at start of roll which would have been normal for any long distance flight. No more fuel was added to it; on the contrary, a very little might have been pumped into tank 1. The fuel transferred forward from tank 11 was put into the engine feeder tanks 1 to 4. This of course was not enough to compensate for the demands of OL593s operating at TOP with afterburner, so these tanks were running down and would have been topped up (tanks 1 & 2) from tank 5 at some point.
5. What actually happened was that the take off acceleration threw the fuel to the back of the tank so that the free surface volume was confined to a small zone in the upper forward region of the tank. When the rubber struck the rear part of the tank undersurface the fuel above it was constrained by a solid wall, which was enough to generate the reflected shock waves.

Lancman 13th Dec 2017 15:37

@ CliveL

Thanks for that detailed and very interesting description of the fuel handling on Concorde and I agree that 17% ullage does seem to be very high, I've never come across a figure that high, ever. But your paragraph 5 seems to indicate that it was a jolly good idea from a flight safety point of view. The risk of tank rupture was increased because of the limited free surface volume. I'm just interested in what the circumstances were that allowed this restriction to be over-ridden.


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