Concorde question

[Mr.Vortex]

Hi M2 Dude

Thanks very very much for your long reply and good explanation.

- So once we select the Engine schedule to mode Hi or F/O the Prim nozzle will
open wider causing the pressure at the Prim nozzle to drop and hence the
higher flow of the exhaust through the LP turbine = Higher N1 RPM.
Am I understand it correctly?

- According to your reply, the E schedule that will provide the most thrust is
the Low mode since the prim nozzle area will be the smallest among all of the
other mode which mean the highest pressure and temperature.
Am I understand it correctly? And if so why do BA [as far as I know] told the FE
to use Hi mode? Because the higher thrust can be obtain with higher N1?

- Also does the the Hi mode can deliver the higher N1 RPM, does that mean
the Engine control unit must deliver the higher fuelflow rate in order to keep
N2 run at the constant speed [higher N1 speed => higher pressure => more resistance
=> higher Fuelflow require to keep N2 run at constant speed]

Thanks for all of your reply!

Best Regards

Vortex

[galaxy flyer]

Roger

My appreciation for your complement. Anyone, yank or otherwise, who does not appreciate the long term and continuing world wide cooperation that is required for any project like Concorde or Apollo is simply being xenophobic. Today, Boeing has a large engineering bureau in Moscow, BMW has a design office in California.

Many of the engineers that worked on Apollo, 747 and, even, the C-5, were Canadian ex-pats fired from the Avro Arrow program shutdown. BTW, my nomination for least appreciated, least known but most ambitious aircraft design.

GF

[jodeliste]

Hi Landroger
But for those of us who were brought up as engineers in an analog world its not so scary.
remember by the late 60s chopper stabilised amps were well established and drift was much better controlled,
Is it an analog world out there? I think so
rod

[M2dude]

Mr Vortex

- So once we select the Engine schedule to mode Hi or F/O the Prim nozzle will open wider causing the pressure at the Prim nozzle to drop and hence the higher flow of the exhaust through the LP turbine = Higher N1 RPM. Am I understand it correctly?

More or less you are correct yes, but remember that schedule selection was more or less automatic. (E Flyover was armed prior to take-off, and E-MID during approach by the E/O, otherwise it was more or less a 'hands off' afair).

According to your reply, the E schedule that will provide the most thrust is the Low mode since the prim nozzle area will be the smallest among all of the other mode which mean the highest pressure and temperature. Am I understand it correctly? And if so why do BA [as far as I know] told the FE to use Hi mode? Because the higher thrust can be obtain with higher N1?

Oooo no, we are way adrift here I'm afraid. I'm trying not to get too 'heavy' with this explanation, and I've enclosed below the Rolls-Royce E Shedule diagram to try and help clarify everything. (I've edited out the exact equation figures in deference to Rolls-Royce). Where N1/√θ and N2/√θ is quoted, the term 'θ' related to T1 in degrees K/288. (288 deg's K being 15 deg's C). The hotter things are the higher the spool speed scheduled is, and visa-versa for lower temperatures. Only at a T1 of 15 deg's. C (Standard day temperature) does N/√θ equate to N. (But remamber that T1 is TOTAL temperature, that varies with Mach Number).
The use of E LOW above 220KIAS was not only strictly inhibited by the automatics, if you over-rode the automatics and 'hard selected' E LOW, the aircraft would fall out of the sky when reheat was cancelled at Mach 1.7. This was because the low N1/√θ scheduled by E LOW would now invoke an N2/√θ limit (The E3 Limiter in the diagram) and claw off fuel flow by the tonne.
The most efficient schedule for supersonic cruise was E HI which again would be automatically selected.
E-MID was automatically selected during afterburning operation, to minimise the chance of an N1 overspeed on cancellation of reheat. E-MID could also be selected by the E/O for noise abatement approach.
E Flyoverwas as we discussed before used for take-off flyover noise abatement as well as subsonic cruise if desired. (If Mach 1 was exceeded with E Flyover still selected, a yellow NOZZLE light illuminated and E HI would be automatically selected.
I sincerely hope that this blurb is not clear as mud, feel free to ask away.

- Also does the the Hi mode can deliver the higher N1 RPM, does that mean the Engine control unit must deliver the higher fuelflow rate in order to keep N2 run at the constant speed [higher N1 speed => higher pressure => more resistance
=> higher Fuelflow require to keep N2 run at constant speed]

Nope, that is the beauty of it all. Because of the part choking of the LP turbine section of the engine, the pressure changes due to Aj variation were felt exclusively by N1 and not N2. (Clever, these Rolls-Royce guys).
Regards

Dude

[M2dude]

Landroger

It is still difficult to grasp the fact that, with the one exception Christiaan has told us about, all of the control electronics in Concorde were analogue. Some of the little tweaks Dude has just alluded to in his reply about the nozzles and the relationship of compressor speeds, for example. Most of them would be relatively easy - relative is a huge word of course - if they were microprocessor controlled locally and sending/ receiving status and demand data to a bank of central computers. But to do it with analogue signals and controllers is mind boggling.

It always was a bit of a paradox; in terms of fuel price and environmental concerns, Concorde was about 5 years too late. But in ELECTRONICS terms she was 10 years too early. Bearing in mind that the first Intel 4004 was not even commercially available until 1971. When the decision was taken in late 1970 to 're-design' the analog air intake control system into a digital one, there was nothing to fall back on; a BAC custom guided missile processor (used I believe on both the Rapier and Sea Dart SAMs) had to be adapted. This processor was, as I've yawned on about before, comprised of multiple double sided PCBs completely stacked with TTL ICs. In spite of being a total antique and a dinasore (just like me ) this thing was really cutting edge technology at the time, even using a 64 bit data word. The AICS as again I've yawned on about before, was the WORLD's first commercial airborne digital control sysstem, but the Concorde analog stuff in fact worked pretty well indeed.

Galaxy Flyer
As always GF you make your point really well. As far as Concorde went, the very few American (Branniff) pilots who flew her thought she was totally amazing, and the American BA engineers at JFK and IAD absolutely adored the aeroplane.
And back to your 'charriot', the C5 has been a staggeringly successful aeroplane in terms of US service. and is still thriving (big modernisation programme underway). Not bad for an aircraft that entered USAF service in 1969!!!
Regards

Dude

[ChristiaanJ]

Originally Posted by Landroger

It is still difficult to grasp the fact that [nearly] all of the control electronics in Concorde were analogue.
...
How all these signals and rates were calibrated and stayed calibrated is a mystery.

There are several answers.....

One thing to bear in mind is that a lot of the computing was closed-loop, usually with several loops within loops.
Such closed loops do not require a very high precision or very narrow tolerances inside the loop.
In the Concorde AFCS, most of such computing was based on the use of +/-1% components (resistors, capacitors...) which were stable enough over their lifetime, and the ubiquitous LM101A integrated operational amplifier, which had low enough offsets and drift for the application. Occasionally we had to use the LM108 op-amp (more precise) and +/-0.1% components.

And where the analogue electronic computing was totally inadequate, we used... electro-mechanical computing, using synchros, resolvers and servo loops.

As M2dude says "in ELECTRONICS terms she was 10 years too early".
He's right.
She dates from that precise era, where technology changed from discrete components through the very first integrated logic circuits to mass-produced 'airworthy' logic and analogue circuits, but where the micro-processor was still in the future.
She was really the culmination of the "classic" era, before "digital" took over.

I could waffle on for hours... but don't know where to start?
Ask your questions, to let me know what you want to know.

CJ

[Landroger]

Galaxy Flyer

Many of the engineers that worked on Apollo, 747 and, even, the C-5, were Canadian ex-pats fired from the Avro Arrow program shutdown. BTW, my nomination for least appreciated, least known but most ambitious aircraft design.

GF

You're right there GF - the AVRoe Arrow is a complete mystery to me and I've heard of the Martin Baker single seat fighters and the Percival Peregrin!

Roger.

[ChristiaanJ]

Re the Avro Arrow....
I knew about the aircraft, but had to read up again about the history.

Sounds like TSR-2... very different aircraft, very different mission.... but same damn politicians....

CJ

[Nick Thomas]

Landroger
Off topic I know but just in case you have not seen last months issue of "The Aeroplane" there are a couple of articles on the Martin Baker single seater fighters.
Regards
Nick

[Biggles78]

Originally Posted by ChristiaanJ

Sounds like TSR-2...

M2, he mentioned ........ HE MENTIONED IT!!

[Kiltrash]

May I just chip in with what a wonderfull read, and to think this thread started with a simple?? question about the non existant APU 3 months ago!!

ps Landlady where are you?? we need another recollection please from the cabin to break up the technical stuff we may not fully understand but still find totally enthralling in a typical understated British way

ChristianJ and M2dude et al many thanks

[speedbirdconcorde]

Always love to hear stories like this....I am sure there are many more ! Cheers Christiaan ( and m2dude ) for such great information on our beloved icon....

Reg:

Ancient tale.

There's this SR-71 Blackbird stooging around Cuba on a top-secret mission, at FL500+ and Mach 2+.... when they get a call requesting them to change heading "because of traffic at your altitude".
Traffic at THEIR altitude ??
Anyway, they comply, and shortly, yes, there's an Air France Concorde out of Caracas (Air France flew there in the early days) slowly sailing across their flight path.

[ChristiaanJ]

speedbirdconcorde,
You forgot the punchline....

Two guys in full pressure suits and bonedomes and all the rest....
Meeting close on a hundred people in shirt sleeves and summer dresses, sipping a glass of champagne, and just being served hors d'oeuvres.
Same speed, same altitude...

CJ

[Cron]

The accessibility of this thread to the 'man in the street', such as I, has confirmed to us what an astounding example of technical achievement Concorde is (not was!). (I'm going to stick my neck out and suggest that the cancellation of say the A380 would not engender a Pprune thread such as this).

Maybe a bit of a sentimental/daft question but may I ask what personal effects the discontinuation of Concorde had on the crews, the engineers and anyone 'hands on' with the aircraft?

The crews, the engineers and anyone 'hands on' with the aircraft would have known that they were involved with something very special. Moreso I detect from such posters that they seemed to have a relationship with the aircraft which went beyond the normal level of any professional working with interesting technology.

Were these people such well balanced types that they shrugged and took in their stride or was there seething but repressed anger? Was there a feeling of personal loss that such a thing would never happen again?

Haven't worded my question very well but I guess you can see what I'm getting at.

Cron.

[speedbirdconcorde]

Bugger...its past midnight and I'm still reading this thread ! Time to hit the sheets before I find a Concorde vid to start watching lol

As others have said...brilliant thread and great to hear from all the Concorder's...

You are all responsible for my red-eyes in the morning :-)

[Feathers McGraw]

Cron

If you watch some of the more recent Concorde programmes, such as "Concorde's Last Flight", you'll hear and see the reaction of the various people (including our very own Dude) from the BA side of things as they talk about their charge. The AF crews also have that same look on their faces in the few programmes I've seen them in.

I think that Concorde was a running love affair for a lot of people, especially for those that flew her, looked after the passengers and maintained her but the effect of a Concorde pass on just about anyone was noticeable. Every head turned and looked skyward, and kept looking even after the aircraft was out of sight. People who lived below the regular flight paths, who might have been expected to be upset by the noise, used to come outside and watch on every occasion. I've seen almost a whole street appear a few minutes before a departing Concorde that passed over Reading and be rewarded with a great view in brilliant sunshine.

Not many aircraft have that kind of following....

[BN2A]

In my best 'Comic Book Guy' accent - Best Thread Ever......

We've heard from Engineers, Pilots, Designers, 'Ambassadors'.... How about ATC??? Are there any out there with their memories?? Was life slightly different when "No Speed Restriction" was offered and Concorde hit 400 kts+ instead of the mere mortals at +/- 300 kts?? Anything unusual in their handling on the way into LHR/JFK/IAD/BGI etc for sequencing?? Any general anecdotes to recollect?? Heathrow Director, are you out there? Your name sort of gives you away.....

Keep it up everybody!!



PS - Was there ANYTHING on the Charger(ski) that was better or more advanced??

[Mr.Vortex]

Thanks a lot M2Dude

So if we select E Low at M>1.7 the N2 will ovespeed and hence higher fuelflow. Am I understand it right? Also, what E mode provide the
best config shape [lest sat suitable] that provide a con-di nozzle for
maximize thrust. [Not open to wide that exhaust can't reach M1 at the
throat of Prim nozzle].

And another quesrion here, the engine control unit use which parameter to control the thrsut. The EGT, or N2, or P7.

Thanks for yours reply.

Best Regards

Vortex

PS. thanks for your nice graph and fuel vent schematics too.

[speedbirdconcorde]

Feathers,

"If you watch some of the more recent Concorde programmes, such as "Concorde's Last Flight", you'll hear and see the reaction of the various people (including our very own Dude) from the BA side of things as they talk about their charge. The AF crews also have that same look on their faces in the few programmes I've seen them in."

Is this a different show from the discovery programme - if so, is it available on DVD or is it 'streamable' somewhere ?

cheers,

d

[Feathers McGraw]

"Concorde's Last Flight" was shown a couple of months ago, on Channel 4 I think, but my memory may be playing up. No, it isn't, see here.

Concorde's Last Flight - Concorde's Last Flight - Channel 4

It's not on 4OD, so you will have to search other video sites and see if you can find it. Interesting, nothing really new and earth-shattering but some good things in it.