Concorde question

[ChristiaanJ]

Originally Posted by ITman

May I ask you guys another question relating to the book I mentioned earlier, in the same book it shows a Concorde with a Airbus sidestick control. I wondered if anymore information is known on this modification I suspect t must have been quite an systems integration exercise.

ITman, nice question.
I haven't seen any of the detailed (block) diagrams, so I'm not sure at all how the sidestick was "hooked into" the AFCS.

Don't forget Concorde already used "electrical flying control signalling" (aka "Fly-By-Wire")., so system integration would have been easier than on some other aircraft.

For those unfamiliar with the story... F-WTSB, very late in its career, was used for some flight trials with a sidestick controller fitted to the left-hand position (the right-hand seat controls still being the normal ones,and with the right-hand seat occupied by a 'safety' pilot).
The flight test data were later "fed" into the A-320 programme.

How much of the "rate" control and other A-320 control logic was already implemented in the test system is unknown, AFAIK....
Would be interesting to know some more about it, I agree!

CJ

[gordonroxburgh]

The side stick fitted to 201 (in 1977 according to Flight International), was very much proof of concept for what would be the future A320 programme sponsored by the French government, very very limited hours were flown using it apparently (like 10!). The next step I believe in the development was to fit it onto a FBW modified A300 in the early 80s, but for the initial tests to see if a pilot could fly with a "computer joystick" it had to be done on Concorde as this was the only a/c with a suitable FBW system.

It would be good to know how it was done, but I guess it could have been wired into the emergency flight control system, which relied on electrical strain gauge inputs to move the control surfaces if there was a control column jam.

[CliveL]

asc12

Let me ask it this way: Could a student in Aeronautical Engineering calculate the lift and drag for (non-vortex) Concorde using the same equations he would use to calculate lift and drag for say, a 777?

Well yes, there is no magic difference. You could calculate the lift and drag using the same methods as you would for any other delta winged aircraft, or indeed for aircraft with a 'classic' planform. You might have a bit of trouble handling the effects of camber, especially leading edge camber, if you were starting from a clean sheet of paper, but skin friction, form drag and lift curve slope (attached flow) are all calculable by standard methods. You might be pushed to get a decent estimate of lift dependent drag - I spent many hours in my youth looking for wind tunnel results on low aspect ratio delta wings to get some idea of what might be expected, but once you have tunnel tests on 'your' aircraft course there is no problem.

In other, other words... I understand that there's a very different phenomenon developing a chunk of lift at high AoA. But the wing still has a very unique shape and camber, so I wonder if-- when the AoA is *not* as high-- phenomena responsible for our 777 staying up fully apply to Concorde.

Again the answer is yes - in subsonic cruise (0.93M in this case) exactly the same sort of aerodynamics applies - different in detail, but the same in principle.


CliveL

[CliveL]

SSD

I should perhaps add a bit to my first response, which was:

By "Stall" in this case I meant the maximum ift we could use. There was in fact a small 'hiccup' in the lift curve against AoA, but the lift went up again afterwards. However, there was a definite nose-up 'break' in the pitching moment which we took to be the limiting AoA and regarded as a 'stall'

Although delta wings do not stall in the classic sense there is nevertheless a limit to what lift they can provide. As the AoA increases the vortices also increase in intensity, but there comes a point where the vortex flow becomes unstable and the vortex 'bursts', i.e. the circular motion degenerates into chaos and the diameter of the 'vortex' increases greatly.


The point in the vortex track at which this happens moves up towards the wing TE as AoA increases and when it reaches the TE the wing pressure distributions change and you get a break in the pitching moment curve. This happens earlier on one wing if you have sideslip, so you then tend to get a wing drop. This does not meet the airworthiness requirements so effectively vortex bursting over the wing equates to stalling.


[On another thread it has been pointed out that on the FA18 vortex bursting (off the LE extension) has caused handling problems due to interference with the fins]

[CliveL]

Gordon Roxborough
It would be good to know how it was done, but I guess it could have been wired into the emergency flight control system, which relied on electrical strain gauge inputs to move the control surfaces if there was a control column jam



ChristiaanJ

How much of the "rate" control and other A-320 control logic was already implemented in the test system is unknown, AFAIK....
Would be interesting to know some more about it, I agree.

I can't add too much as I was only on the fringes of this.


I think it might have been done by fitting a D/A converter to substitute the digital signals from the sidestick for the normal Concorde stick resolver output. The 'laws' could then be treated as a special case of pitch damper etc. inputs so that the standard Concorde electrical signalling system could be used downstream. I don't know this for sure, it is just a thought - maybe Christiaan could comment on its feasibility.


I think they were looking at at least the rate control but probably not all the envelope protections. Certainly at that time we were having discussions with them about the merits of their FBW laws against the laws we (BAe) were trying out on our BAC1-11 flying test bed. No prizes for guessing who won that argument.


And before anyone asks; no I don't remember (if I ever knew) how we were implementing FBW into the 1-11!


CliveL

[gordonroxburgh]

I think it might have been done by fitting a D/A converter to substitute the digital signals from the sidestick for the normal Concorde stick resolver output. The 'laws' could then be treated as a special case of pitch damper etc. inputs so that the standard Concorde electrical signalling system could be used downstream. I don't know this for sure, it is just a thought - maybe Christiaan could comment on its feasibility.

My only reasoning for guessing on the Emg flight system was that its would be easy to turn on and off and recover to the normal flying controls.

For a very short test programme, well ahead of any A320 programme which did not come about till 1984, I suspect this was no more than a belt and braces to see if you could fly an aircraft from a side mounted stick.

[Landroger]

GordonRoxburgh

For a very short test programme, well ahead of any A320 programme which did not come about till 1984, I suspect this was no more than a belt and braces to see if you could fly an aircraft from a side mounted stick.

That cannot of been the sole objective, surely Gordon? Concorde was far too complex and expensive an aeroplane to simply want to prove that with her? Wasn't the F16 flying then? That had side stick - and a 'lay down in the bath' seating position didn't it?

As for the aerodynamics, what a fascinating discussion! I'll readily admit it is mostly on the fringes and way above my understanding, but I can hang on to enough of it to make the subject utterly intriguing. My maths are not and never were anywhere near good enough to make this a career choice, but the image conjured of vorteces and laminar flows and shock waves is quite beautiful.

Thanks again everyone.

Roger.

[CliveL]

Gordon,

[quote] My only reasoning for guessing on the Emg flight system was that its would be easy to turn on and off and recover to the normal flying controls. [quote]

I see what you mean, but surely it would be just as easy to insert a kill switch in other systems?

I'm with Landroger on this in that I feel they would want to do a lot more than just find out if aircraft can be flown with a sidestick. I would expect them to want to know about how much stick movement was optimum and this they could not do with the EMG solution (if I have read your remarks correctly that would have been a stick fixed/force signalled system?)

I am also pretty certain that they investigated control laws; with a simple 'can you fly with a sidestick?' system they would surely be effectively in a electronic version of mechanical signalling?, and although you could fly the bird in mechanical it would be making life difficult for yourself, which is the last thing you want to do when investigating something really new.

[DozyWannabe]

I think Gordon probably meant "airliner" rather than "aircraft".

The implementation of FBW on the F-16 was intended to solve a very different problem than that of the A320 series. The F-16 was one of the most maneouverable fighters of it's day, but the way General Dynamics achieved that was by having an aerodynamically unstable airframe that *required* constant computer correction to keep her airborne and going in a straight line. The A320 was designed to be as aerodynamically stable as any other airliner, but the FBW was simply designed to assist the pilot by easing the workload when it came to actually controlling the thing, as well as provide safety features as backstops when things got hairy.

The only Western analogue FBW aircraft of the time of comparable size to an airliner (IIRC) were the Avro Vulcan and Concorde. France had no Vulcans, so the airworthy test Concorde they had to hand was the obvious choice.

[M2dude]

I personally doubt very much if the Emergency Pilot would be the 'way in' for the sidestick input. EFC ROLL commands were inputed from the SFC computer to the Autostab computers as 'stab demands' and therefore drove the MIDDLE and OUTER elevons only for roll. To make matters worse, if your test flight was really 'exciting' and you found yourself at any time at Vmo + 20 KTS, roll control would be through the middle elevons ONLY. I'm with CliveL in that the most likely scenario would be for the demand would feed via a D/A converter somehow. (It would be great to find out though).
I would have thought that the whole venture was a proof of concept by SFENA for future implementation in the Airbus family. This excersise would have been both costly and highly complex at system level, any other reason would really have been quite daft.

Best Regards
Dude

[gordonroxburgh]

If the Flight article from the 80s that says only 10 hrs of flying was done is correct, it can only have been for limited in flight handling and not anything approaching the limits of the understood flight envelope......and I sure you would not have been contemplating take offs and landings.

A few of the Toulouse ex pats might be the people who would know, Dudley Collard etc...

[spfoster]

Farewell Tour Details

Hi,

I am trying to find out some details of the Farewell Tour for a project I am undertaking.

The flights I refer to were are the following:

Heathrow - Birmingham - Heathrow (20 October 2003)
Heathrow - Belfast - Heathrow (21 October 2003)
Heathrow - Manchester - Heathrow (22 October 2003)
Heathrow - Cardiff - Heathrow (23 October 2003)
Heathrow - Edinburgh - Heathrow (24 October 2003)

All of these flights were scheduled to leave Heathrow at 10:00 hours and arrive at their respective locations at 11:45, and the return was to leave at 16:05 and arrive at Heathrow at 17:45 (apart from the last Edinburgh flight which left Edinburgh earlier in order to get to Heathrow around 16:00)

Does anybody have any details of the routings that these flights took? I have some information about the Edinburgh flight but I cannot find anything out about the others, if anyone can supply me with anything it would be very much appreciated.

Also, were these flights purely subsonic or was there a short supersonic section in there somewhere, after all it doesn't take 1:45 to get to Cardiff, Birmingham or Manchester etc if you go direct.

Many thanks in advance for anything you can offer.

Regards,

Steve.

[gordonroxburgh]

Steve,

I don't have exact details, but I understand the Manchester, Birmingham, Cardiff and Belfast flights were supersonic "round the bay". The round the bay was essentially a trip out to 8w on the normal supersonic flight path, turning 70 miles around the tip of lands end, then decelerating back in down the English channel over Guernsey, where they then routed to the relevant airports.

Edinburgh was supersonic out over the north sea.

[M2dude]

gordonroxburgh

If the Flight article from the 80s that says only 10 hrs of flying was done is correct, it can only have been for limited in flight handling and not anything approaching the limits of the understood flight envelope......and I sure you would not have been contemplating take offs and landings

It matters not I'm afraid Gordon. I would not have thought that anyone would design ANY flying control system, experimental or otherwise, that does not have full potential authority in all axis. As we do not know what the PROPOSED flight regime was, on the part of SFENA and Aerospatiale,we also can not assume that any particular manoeuvr would not have been considered. (But as I said before, it would be great to find out the whole story).
The limited authority for roll autostabilisation (and hence Emergency Flight Control) was of course a very deliberate piece of design. (You could test the Emergency Pilot on the ground at ADC Test 2 (Which simulated several seperate overspeeds, including Vmo +20) and when you put in a roll demand (against some resistance), only the MIDDLE elevons deflected. It really looked wierd on the ICOVOL as well as outside the aircraft.
(To any chaps or chapesses who are not aware, above Vmo+20 KCAS, a system known as OUTER ELEVON NEUTRALISATION was invoked, where any input demand to the outer elevons was met by an automatic equal and OPPOSITE input, that of course completely neutralised the demand, giving a zero OUTER elevon deflection).

Best regards
Dude

[spfoster]

gordonroxburgh,

Many thanks for that, I had a feeling that's how it would have been.

I assume the return would be routed from say Birmingham or Manchester towards UPGAS to enable it to pick up the normal routing to do the trip out to 8 West and then back into Heathrow.

Not sure how the Belfast one would have routed though, back down to the Bristol Channel via the Irish Sea, or cut across Ireland and pick the track back up when she was back over the Atlantic?

Thanks,

Steve.

[johnjosh43]

FBW Aircraft of the 60s

"The only Western analogue FBW aircraft of the time of comparable size to an airliner (IIRC) were the Avro Vulcan and Concorde. France had no Vulcans, so the airworthy test Concorde they had to hand was the obvious choice."

The Vulcan wasn't pure fly-by-wire. It's control surfaces were remotely signalled but had a physical connection rather than electrical. Sort of fly-by-stiff wire :-)

One of the spin-offs of having Concorde at Manchester is that it is used by many different organisations for events. One a while back had a discussion about Technology benefits due to Concorde, part of that was about Concordes "1sts". First FBW was challenged as the feeling was that there must have been another by then. Nobody could think of another so it stood the debate. Is anyone aware of any others ?

[MFgeo]

FBW Aircraft of the 60s

If you limit consideration to aircraft that entered serial production, you may be correct. If aircraft that were prototyped and flew are included then the Avro Arrow was probably the first, as it was designed, flew a partial test program, and got cancelled all prior to 1960!

[ChristiaanJ]

Originally Posted by johnjosh43

The Vulcan wasn't pure fly-by-wire. It's control surfaces were remotely signalled but had a physical connection rather than electrical. Sort of fly-by-stiff wire :-)

Not the first time that's mentioned.
Do you (or does anybody ele) have a schematic of the Vulcan system?
It should be on my CD of the Vulcan manual, but unfortunately my CD drive is on strike.....

MFgeo, I think we're talking Europe here... the Avro Arrow was Canadian,so I would think it unlikely the flight test results would have been available to Airbus.

CJ

[gordonroxburgh]

It matters not I'm afraid Gordon. I would not have thought that anyone would design ANY flying control system, experimental or otherwise, that does not have full potential authority in all axis. As we do not know what the PROPOSED flight regime was, on the part of SFENA and Aerospatiale,we also can not assume that any particular manoeuvr would not have been considered. (But as I said before, it would be great to find out the whole story).

Knowing more now about the safety system, I am agreement with you, getting straight in at resolver level looks the best bet on how it may have been done.

[CliveL]

As we do not know what the PROPOSED flight regime was, on the part of SFENA and Aerospatiale,we also can not assume that any particular manoeuvr would not have been considered. (But as I said before, it would be great to find out the whole story).

I have some feelers out to see if I can get Dudley C's contact details. As Gordon says, he would/should be a good source - keep fingers crossed

CliveL