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CliveL
I've noticed that several postings refer to the production AICU as a 'digital' control system. Strictly speaking it wasn't; it was a hybrid digital/analogue system where the inner dynamic control loops (the closed loop part) were analogue systems operating to maintain limits defined by the digital arithmetic processors. This allowed us to have quite sophisticated control 'laws' which would have been next to impossible with a pure analogue system. But as you say Clive, none of the control law sophistication (including the synthesising the intake face total pressure and local Mach numbers from mainline aircraft raw air data) would have been possible using analog computation. Best regards Dude :O |
Thanks all - I'd forgotten a lot of the SFC stuff. (May need to visit the dark corners of the loft in the near future).
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Mr Vortex
, What does the function of the Thrust recuperator and how does it work? Best Regards Dude :O http://i1237.photobucket.com/albums/...11/Recupe2.jpg http://i1237.photobucket.com/albums/...ecuperator.jpg |
This just goes on getting better. Welcome Clive!
After all the high tech stuff I have a much more prosaic question. Looking out of my Devon window this morning I could see aircraft streaming up the channel, and by checking their positions on Flightradar 24 (sad, I know) I know that I can see craft at fl350+ nearly the whole way across the channel, so it occurs to me that I should have been able to see AF Concordes on their way into CDG, but never did (although I certainly heard them). Would Concorde have been visible from the ground at cruising height, and would it have left contrails? |
Contrails
Concorde would produce contrails in the same conditions that a conventional aircraft would. I've seen pics of it contrailing in supercruise, and it's a big trail.
Outbound, for reasons of best efficiency, the subsonic cruise would be at FL260 or 280 so contrailing was unlikely, but I would expect the occasional contrail inbound (cruising in low- to mid-30's) so you were unlucky not to see one if you were looking at the right time. It would have been no more or less visible on primary or secondary radar than other commercial types. It would be hard to see with the naked eye, unless the sun was reflecting off it. |
Contrails
http://i1237.photobucket.com/albums/...1/100_1299.jpg
I took this one over the Atlantic, of G-BOAF, BA002 at Mach 2 FL 560 from G-BOAD FL 480 Mach 1.9 (test flight) in July 2003. (Mach 3.9 closing :D). Best rgards Dude :O |
Originally Posted by Shanewhite
(Post 6139209)
Would Concorde have been visible from the ground at cruising height, and would it have left contrails?
Shortly before the French end-of-service, a small group of French enthusiasts set out in a boat (fishing boat I think) to waypoint 'TESGO' in the Channel, to hear and capture the supersonic bang one more time (TESGO is already beyond the supersonic accel point). They brought back a video which has become a classic, with both Concorde and a contrail overhead and a recording of the supersonic bang. A quick search on the net for "TESGO" or "Operation TESGO" didn't produce anything, but I will make some enquiries. CJ |
Christian, is this the video you are refering to? YouTube - PHY NYC Concorde breaks sound barrier (double bang)
Post #879 http://www.pprune.org/tech-log/42398...ml#post6129540 - Just guessing now, but Bellerophon were you a Concorde Pilot by any chance. :E I read your vivid description and realised that I must have been peeling onions at the same time. :O Thank you for that sensational work of art, drawing us a picture of that take off while at the same time making it sound like it was no harder than taking a breath, though I have no doubts this was an extremely complex and demanding proceedure that required a level of crew synergy unknown of at that time. Again, my THANKS for that precious insight into your world. This in no way excludes all the other contributors to one of the two best threads on this Forum. All you guys made and were part of a very special piece of history and now like the famous "Few" will never be forgotten partly as a result of this thread. I do hope Landlady posts back with pieces that didn't make it into her book. :ok: |
Originally Posted by Christiaan
A quick search on the net for "TESGO" or "Operation TESGO" didn't produce anything, but I will make some enquiries.
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Thanks Biggles78 and SilverCircle, that's it !
Those are the essential 30 seconds from a longer video that tells some more about the preparation, etc. CJ |
Originally Posted by ChristiaanJ
Clive, I think we need your help here. I was also told, both while I was at Fairford and during one of my two ground school courses at Filton in the early 80s, that the lateral stiffeners (underneath the wing just inboard of the Rib 12 area) were added to reduce outer wing flexure and in themselves gave us a performance penalty. Can you shed any light Clive?
I had never heard of any such stiffeners before I started reading this thread. The wing inboard of Rib 12 was pretty stiff as was Rib 12 itself, so it didn't need stiffening there. I don't see how tiny stiffeners like that, mounted INBOARD of Rib 12 could ever have have any significant stiffening effect on the wing OUTBOARD of Rib 12. if anyone wanted to stiffen the outer wing it would be much more efficient to do it with internal structure, so any external addition would have been some sort of panic measure and I think I would have heard of it. The external shape of the excrescence looks to me much more like a streamlined fairing to get some sort of cable or pipe from A to B when for some reason it couldn't be passed through inside the wing. In this connection I see that the objects in question run fairly close if not along, area where one might have something going from tank 5a to 6 or 7 to 7a. Yes there would be a small performance penalty for these fairings. In summary I don't really know, but would need a lot of convincing that these things really were external stiffeners! CliveL |
CliveL,
Wasn't me, honest, guv. 'T was that other dude... Any chance of a pic or a drawing, M2dude? It seems almost impossible to me that it was 'something' between inner and outer wing, since it would have had to 'jump' over the bathtub covers. IMO everything went through rib 12, not under or over it. CJ |
Originally Posted by ChristianJ
Wasn't me, honest, guv. 'T was that other dude...
Any chance of a pic or a drawing, M2dude? It seems almost impossible to me that it was 'something' between inner and outer wing, since it would have had to 'jump' over the bathtub covers. IMO everything went through rib 12, not under or over it. 'Bathtub covers' rings a bell - we did have an issue designing fairingsfor these that looked remarkably like those in the photographs I've been looking at, but I'm damned if I can remember what the bathtubs were! (getting old again) Aren't those so called stiffeners actually the bathtub covers? Or have I completely misunderstood the question? CliveL |
Originally Posted by M2dude
HOWEVER, this system was fitted to the #1 system only (1 & 2 were used on alternate flights) and there was no performance penalty when the thing was not working.
Dude, Do you know how the #2 system was exhausted if it wasn't through another thrust recovery nozzle? We were never going to throw away 600 lbf thrust every other flight - not on Concorde where we sweated blood to get the parasitic drag down! Any chance that there was a common discharge point even if the two packs were used alternately? CliveL |
That's not my recollection - no.2 system used for inbound flights, and this used the stbd outflow (oops! discharge) valves.
No perf penalty, as 'Dude noted. I vaguely recall being told that the drag from the recuperator cancelled a lot of the recovered thrust. I've no idea how true it was......... |
no.2 system used for inbound flights, and this used the stbd outflow (oops! discharge) valves. No perf penalty, as 'Dude noted. I vaguely recall being told that the drag from the recuperator cancelled a lot of the recovered thrust. I've no idea how true it was......... I know it sounds crazy, but that cabin air had to be dumped somewhere, and without those thrust recovery nozzles all the energy it contained would be lost, so that a net zero is actually a win! CliveL |
Originally Posted by CliveL
but I'm damned if I can remember what the bathtubs were!
OK all. On the 'blunties' and most other aircraft (subsonic or supersonic) there is a fuselage, and there is a wing. The wing is connected to the fuselage by only a few very big bolts, linking a few very big forgings. Concorde is different, right? Right. Fuselage and inner wing are the same structure, and there were no "big bolts" that allowed you to separate fuselage and inner wing once the aircraft was built. The only separate "bits" were the outer wings, the parts just outside the engine nacelles. So 'rib 12' was the rib where the inner wing ended, and where the outer wing (built by Dassault, rather than Aerospatiale, actually) was attached. Rib 12 actually was two halves, the one at the outboard side of the inner wing, and the one on the inboard side of the outer wing. Both machined numerically from single 'blanks'... And no, these two halves were NOT just bolted together with a few massive bolts. They were bolted together with hundreds of bolts in all. I did say Concorde was different, no? Words now fail me, and I'll have to find or scribble some drawings ASAP. In brief, so far.. each half of rib 12 had MANY machined "bath tub shaped" slots allowing to insert a bolt between the two halves, and bolt the outer wings to the inner wings. And simplistically, the 'bath tub covers' were just small sheet panels held in place with fasteners fitted inside the 'bath tub' slots. I should know.... I still have the scars of helping, one day, to refit a batch of them on Delta Golf at Brooklands CJ |
A couple of points on some of the latest entries
Discharge valves We definately used alternating systems outbound and inbound and only No 1 system had thrust recuperators. I think the original idea was that No 1 system would be used always with No 2 sytem being a back up. However from the start BA operated as I said alternating per sector so as to be sure that both system were working. The same logic went for the engine starting ignitors which were used Lh or Rh per sector. This logic caused more problems with starting than any other although a way was found to over come this problem under wing Not sure if I am on the same thread as others but there were definately strengthening straps / doublers fitted on the underside of the wing outboard of the engines, which were on a wing root/wing tip alignment. This surprised everybody as they seemed to go against all the need for limiting drag that had been impressed on us during the lectures. These strengthening straps were fitted a few years after the start of service due to small cracks appearing in the outer wing, and only seen on BA aircraft. This was put down to the fact that in the early years BA Concordes flew heavy and subsonic for extended periods across Europe, on their route to Bahrain, whereas Air France aircraft always accelerated shortly after take off Also either side of the engines there were two tubes on the underwing which went fore /aft. These tubes were the drain outlet for their respective engine dry bay and directed any fluid to the trailing edge of the wing. Mind you all this is some 30 years ago so the old grey matter could be playing me tricks |
A picture is worth a thousand words they say, but the bathtub joints can't be the fairings showing just outboard of the nacelles as they (the bathtub joints) are flush
CliveL http://i1080.photobucket.com/albums/...vel1/Rib12.jpg |
Originally Posted by Brit312
Not sure if I am on the same thread as others but there were definately strengthening straps / doublers fitted on the underside of the wing outboard of the engines, which were on a wing root/wing tip alignment. This surprised everybody as they seemed to go against all the need for limiting drag that had been impressed on us during the lectures.
These strengthening straps were fitted a few years after the start of service due to small cracks appearing in the outer wing, and only seen on BA aircraft. This was put down to the fact that in the early years BA Concordes flew heavy and subsonic for extended periods across Europe, on their route to Bahrain, whereas Air France aircraft always accelerated shortly after take off Also either side of the engines there were two tubes on the underwing which went fore /aft. These tubes were the drain outlet for their respective engine dry bay and directed any fluid to the trailing edge of the wing. If there were spanwise straps fitted to BA aircraft after a few years in service that was after my time. They would be a sort of 'crack stopper' and despite the drag would have to go spanwise to carry the loads and would have to be external at that stage in the aircraft life. They would give some additional bending stiffness, but not very much I think. they are probably invisible in any photographs I have - the 'fairings' I have been chuntering on about are the dry bay drains you have just described. I must admit I am surprised by your remarks on the thrust recovery nozzles though. CliveL |
Since a picture's worth a thousand words, if you guys would like to point to the strengthening straps/spars/thingies on this?
http://thephysicsguy.com/pixfolder/A...Underside2.jpg |
CliveL,
Thanks for the picture, saves me a thousand scribbles. And it also shows my mistaek... rib 12 was only inboard. The outer wing did not have a "rib 12", it was the upper and lower edges of the skin that had their own "bath tubs". CJ |
CliveL
Dude, Do you know how the #2 system was exhausted if it wasn't through another thrust recovery nozzle? We were never going to throw away 600 lbf thrust every other flight - not on Concorde where we sweated blood to get the parasitic drag down! Any chance that there was a common discharge point even if the two packs were used alternately? ChristiaanJ Any chance of a pic or a drawing, M2dude? It seems almost impossible to me that it was 'something' between inner and outer wing, since it would have had to 'jump' over the bathtub covers. Mike-Bracknell Since a picture's worth a thousand words, if you guys would like to point to the strengthening straps/spars/thingies on this? A very happy Christmas to everyone here; Personally I am working right through Christmas AND New Year (darned aeroplanes) :{ Dude :O |
Unfortunately Mike your photo is a little too far outboard to show them. We need to go a little more inboard and slightly further aft. I've been through my photos and can't yet find one. (Honest CliveJ, it is the truth, they DO exist Happy Christmas to all CliveL |
Originally Posted by M2dude
(Post 6141165)
CliveL
Unfortunately Mike your photo is a little too far outboard to show them. We need to go a little more inboard and slightly further aft. I've been through my photos and can't yet find one. (Honest CliveJ, it is the truth, they DO exist :E). http://www.concordesst.com/returntof.../fbistres2.jpg |
Sorry to be picky Mike, but didn't Brit 312 say the cracks were only found on BA aircraft? So maybe (probably) AF never fitted the straps.
CliveL On the other hand, if we ignore Dude's instruction to go inboard and aft, then there could be spanwise straps ahead of/behind the 'F' of the registration out past the hyphen. Best leave it to those who know I think! |
Mike,
On your original photo you can see perhaps 5 span wise smudges just forward of the dotted red line on the engine. On your second photo you can see them again with three just forward of the registration letters. The problem is that the aircraft in the photos are too clean and so they show up less. These straps were quite neatly done but for Concorde they were rather agricultural. As far as I remember only BA aircraft suffered this problem for the reasons stated before, but I am not surprised to see that Air france aircraft were also modified. |
http://i1080.photobucket.com/albums/...vel1/Fig32.jpgChristian asked if there was an aerodynamicist in the house - I guess that would be me!
The original question was whether there was any vortex activity in subsonic cruise, but the discussion went on to ask about designing for subsonic drag I think. The answer to the first bit is that the vortex flow started in a gentle manner from about 6 or 7 deg AoA and got steadily stronger. Depending on the chosen cruise speed and the aircraft weight, the subsonic cruise AoA would have been in the region of 4.5 to 5 degrees, i.e. below any significant vortex development. 6/7 deg would correspond to something in the range 250 to 280 kts probably (I haven't done the sums) What we were trying to do for subsonic cruise was to have what is known in the trade as 'leading edge suction' acting on a nice bit of forward facing area so that it tried to drag the aircraft forwards as it were. As you can see from the diagram the prototype aircraft had a much more cambered LE so that both suction and forward facing area were very reasonable. This prototype shape was nicely rounded so that LE separation and top surface vortex generation started at a higher AoA than on the production aircraft. Unfortunately this shape, which featured a rather sharp LE on the undersurface, generated a vortex on the undersurface of the wing in supersonic flight and low AoA (near zero 'g'). This vortex got into the intake and caused the engine to surge, so we had to redesign the LE ahead of the intakes as shown. This cost us a little subsonic drag, so you can see from the diagram what you need to do to keep subsonic cruise drag down. Hope this answers the questions CliveL |
Re: stiffeners. This is as close as I can match to the area in question from pics in my collection, no further aft view from this angle unfortunately. Alpha Alpha at East Fortune.
http://img.photobucket.com/albums/v2...stiffeners.jpg |
Happy memories? I'm not sure.
M2Dude wrote:
I hope the enclosed diagram helps to put it all in place. Best Regards Thanks Dude, that really puts texture to cold facts. While you are all taking the trouble to explain a hundred small elements of Concorde's make up, I'm sure many of the readers hooked on this thread will be blinking back tears of insipient brain damage at some of the control logic you have all spoken about. Certainly it sounds, from time to time, that there were a million little black boxes dotted all over her airframe. I suspect however, that many of the 'terms' and 'laws' spoken about are simply a gate or two, perhaps an op' amp, placed in a larger circuit that modulates the output of that board, thus creating the law or term. I know you have answered my original question about calibrating all these circuits, but nothing I've seen here yet has reduced my frank admiration for the guys (and girls?) who designed the electronics for Concorde. It required true creativity and instinctive engineering that I doubt still exists. Digital control is a hell of a lot easier than Analogue - in my humble opinion. :) Seasons greetings to everyone on this thread, especially to our (growing - welcome Clive :)) band of Concorde experts. Roger. |
Thanks again for a great pics and great explanation.
I'm was wondering that, according to the manual and some document said that the vortex lift start to form on wing tip first. Why's that happened? Why not the root of the wing first? Is it cause by the local wing tip vortex push the air causing more upwash and hence more effective AoA causing it to reach the stall AoA first is that right? Also, does the wing vortex on the Concorde has an influence or the effect on the rudder? Thanks for your reply. :ok: Best regards |
Originally Posted by CliveL
(Post 6141242)
Best leave it to those who know I think!
The AF pic was the best I could do, but i'm glad I didn't mess up too bad to miss out the bits in question for a second time! Merry Xmas to you and to everyone else who's kept the SLF like me informed and amused for months on this thread. :ok: |
Originally Posted by Coffin Dodger
(Post 6141419)
Re: stiffeners. This is as close as I can match to the area in question from pics in my collection, no further aft view from this angle unfortunately. Alpha Alpha at East Fortune.
M2dude will have to confirm that the 'lateral stiffeners' he is thinking of are indeed the very roughly 2' long and 5" strips at the location of each spar just outboard of the engine, that are very clearly visible on Coffin Dodger's photo of 'AA. If so, they are indeed shown in the structural repair manual and listed as 'doublers'. There are ten of those, from spar 62 to spar 71. Reading "between the lines", the modification dates from about 1978, and was applied by successive service bulletins to both the BA and AF aircraft. CJ |
A little p.s. from me - having looked at Clive's diagram on this page showing the bathtubs, aren't the strengtheners the oval cups outboard of the main fixings on the page? with one pointed to by the words "Bottom machined skin panel"?
This looks like it's another layer of shear in order to fulfil the brief of working around the reported skin problems in that area. Just strange it had to break the surface like that? |
Originally Posted by Mike-Bracknell
(Post 6141620)
The AF pic was the best I could do
http://img.photobucket.com/albums/v3...trespprune.jpg and as you see, they show up quite clearly on Fox Bravo as well. Judging by the page dates in the SRM, BA started it all, and Air France followed, with all the aircraft being modified by 1981. But that's just my guess. CJ |
Originally Posted by Mike-Bracknell
(Post 6141637)
A little p.s. from me - having looked at Clive's diagram on this page showing the bathtubs, aren't the strengtheners the oval cups outboard of the main fixings on the page? with one pointed to by the words "Bottom machined skin panel"?
You're looking at a generic picture of the junction between the upper and lower skins of the innner and outer wings at the level of rib 12, which is the rib just outboard of the engines. The 'sample' you're looking at in that diagram has been "cut away" between two spars. The strengtheners are on the spars themselves, so they don't show up here. CJ |
[xxxxquote=Mike Bracknell] Trust me, i'm definitely just here for the ride (so to speak) and quickly defer to you and the others who definitely know! Mike Bracknell[xxxx/quote]
Hell Mike, I meant I should leave it for others who definitely know, not you! [xxxxquote]A little p.s. from me - having looked at Clive's diagram on this page showing the bathtubs, aren't the strengtheners the oval cups outboard of the main fixings on the page? with one pointed to by the words "Bottom machined skin panel"? This looks like it's another layer of shear in order to fulfil the brief of working around the reported skin problems in that area. Just strange it had to break the surface like that? [xxxx/quote] I don't think so Mike, there are far too many of them. It looks more like 'pocketing' of the machined skin to reduce weight; and incidentally that SA overdid it, since there were clearly cracks developing along the spanwise joints between the various wing sections. Incidentally, doesn't that picture show ever so clearly why designing and fitting that postGonesse Kevlar liner to the lower skins was such a difficult job! [xxxxquote=ChristiaanJ]If so, they are indeed shown in the structural repair manual and listed as 'doublers'. There are ten of those, from spar 62 to spar 71. Reading "between the lines", the modification dates from about 1978, and was applied by successive service bulletins to both the BA and AF aircraft. [xxxx/quote] Yes, I agree, they look like skin doublers put on as a repair job, and that makes (to me) a lot more sense than additions to increase outer wing stiffness. What has confused me from the beginning was that I equated "outer wing stiffness" with "outer wing torsional stiffness" because I could see why somebody might want to increase that but I couldn't, and can't, see why anyone would want to increase outer wing bending stiffness - if you get a little more dihedral who cares? But additional material to increase or recover fatigue life is another matter altogether. Why external? Just look at that drawing - where could you add additional bending material easily? [xxxxquote=Landroger]Digital control is a hell of a lot easier than Analogue - in my humble opinion.[xxxx/quote] Depends when you were born Roger. Now if you came into this world before WW2 ...... [xxxxquote=Mr Vortex]I'm was wondering that, according to the manual and some document said that the vortex lift start to form on wing tip first. Why's that happened? Why not the root of the wing first? Is it cause by the local wing tip vortex push the air causing more upwash and hence more effective AoA causing it to reach the stall AoA first is that right? Also, does the wing vortex on the Concorde has an influence or the effect on the rudder? [xxxx/quote] Ah! this gets a little complicated. Every lifting wing generates a pair of vortices at the tip, but these are not the vortices most people associate with Concorde. The massive vortices you see when the air is moist and the water vapour condenses out because of the drop in air pressure inside the vortex start, as you suggest at the wing root from that highly swept leading edge. The wingtip vortices are still there, even when the main vortices are doing their stuff, so Concorde actually has two sets of vortices acting on the upper surface, although this is not obvious to the casual observer. Simply, the wing vortex has no effect on the rudder. But whilst I am writing about vortices, can I digress to talk about the 'moustaches' aka GT6. Somebody, I forget who, asked about their use for controlling longitudinal stability and somebody else replied, quite correctly, that they were a contribution to lateral stability. What was happening without them was that high AoA (by which I mean in excess of about 10~12 degrees) the 'crossflow' on the front fuselage generated a pair of small vortices which, in sideslip, wandered across the base of the fin. This gave some sidewash that cancelled the 'incidence' coming from the sideslip itself so that the bottom of the fin was effectively operating at zero slip and therefore zero lift. Result - the weathercock stability dropped to virtually zero for small sideslip angles. The small vortex generators (Generator Turbillon or GT) had the effect of fixing the location of the origin of the forebody vortices so that they didn't wander - in fact they tended to become entrained into the main wing vortices - problem solved. Now if I can sort it out I will try to upload some pretty pictures showing those two sets of wing vortices. CliveL |
http://i1080.photobucket.com/albums/...l1/flowvis.jpg">
Dammit! I thought I had read that [xxxxquote] gave me one of those pretty text boxes ah well, back to the drawing board..... Unfortunately the only flow visualisation pictures I have are taken at AoAs where the tip vortex has been swallowed by the main vortex, but I thought I would paste them anyway as most people would never have seen them. In this one you can see the forebody vortices quite clearly (the bluegreen streaks) but since it is a zero sideslip case they don't go anywhere near the fin. On closer inspection, maybe you can just see the wingtip vortices as separate bits of curly white smoke very close to each wingtip. I'm not going to risk losing all that typing trying to attach a second picture, so I will send that separatelyhttp://images.ibsrv.net/ibsrv/res/sr...inksbuddie.gif CliveL |
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What an amazing pictures!!. Thanks CliveL:ok:
So does the nose stake of the aircraft that sit below the Capt/FO sliding window is what you're refer to the GT6 things right? And if possible, :sad: I would like to know why the vortex start to form on the wing tip [The outer wing part] first and the moving toward the wing root [inner wing part] as the AoA increase. Thanks again Best regards |
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