19th Aug 2010, 11:16
permalink Post: 25
Biggles78
Stupid, you? no way!! (Besides, I'm Mr Stupid of the aviation world, that's my title
). The thing is, out here in the world of flying machines, there are almost an infinite number of questions (and hopefully answers too). This applies to just about all aircraft from the Wright Flyer up!!.
Keep asking away, there are so many of us Concorde 'nuts' out here who are more than happy to help out/bore the socks off you.
Fuel burns: The problem was that when flying slow/taxying, Concorde was an extreme gas guzzler, even when idling each engine burnt around 1.1 tonnes/hour (so every 15 minutes after push back meant over a tonne gone). A typical taxi fuel would be around 1.4/1.5 tonnes, depending on the runway in use on the day. I'd have to leave it to some of my pilot/F/E friends to remember some of the specific fuel burns after take off etc, but I can at least give you some interesting consumption figures:
At the beginning of the take off roll, each engine would be burning around 21 tonnes/hour. (Made up of around 12 T/Hr dry fuel (Fe) and 9T/Hr afterburner (reheat to us Brits) fuel (Fr). As Fr was scheduled against Fe, as a function of inlet total temp (T1) by the time V2 was reached (around 220 KTS) the rising T1 has pushed the total fuel flow (Ft) up to a staggering 25 tonnes/hour/engine. As i've pointed out before in previous topics, although the afterburner only gave us a 17% improvement in take off thrust, it was responsible for around an 80% hike in fuel burn. (Hence that is whay it was only used sparingly). However when reheat was used for transonic acceleration, it used a dramatically reduced schedule (roughly a 60% rise in fuel flow) , so it was not quite as scary. The afterburner would be lit at the commencement of the acceleration (0.96 Mach) and cancelled completely at 1.7 Mach. After this time the aircraft would accelerate on dry power only up to mach 2 and beyond. (The cooler the temperature the quicker the time to Mach 2). On an ISA+ day, it sometimes felt that the aircraft was flying through cold porridge, and could take quite a while to get to Mach 2 after reaheat cancellation, where as on a nice ISA - day, she would go like a bat out of hell, and the AFCS would have to jump in to prevent overspeeds.
Before I hit some more numbers, let me say that with Concorde, TOC = TOD!! After reheat cancellation at Mach 1.7, the aircraft would be at FL 430. The aircraft would climb at an IAS of 530 KTS until Mach 2 was reached at fractionally over FL500. From then on the aircraft would cruise/climb as fuel was burnt, up to a maximum of FL600. On warmish days (eg. the North Atlantic) TOD would typically be around FL570-580. On a cool day (the lowes temperatures would of course be reached in the more tropical regions; the LGR-BGI sector encountered this), FL 600 would be reached easily and she would love to climb some more. BUT, the aircaft was only certificated to 60,000' with passengers onboard, for decompression emergency descent time reasons, and so we were stuck with it. The pity is of course, the fuel burn would have been improved, but we never were able to take advantage of this. On test flights however, the aircraft would routinely zoom climb to FL 630. On her maiden flight, aircaft 208 (G-BOAB) reached an altitude of 65000'; the highest recorded Concorde altitude was on one of the French development aircraft, which achieved 68,000'. On a technical point, the analog ADC's were 'only' calibrated to 65,000'.
Anyway, back to some figues; at Mach 2, 50,000', the typical fuel burn per engine would be around 5 tonnes/hour, falling to around 4.2 tonnes/hour at 60,000'.
THE NOSE You are quite correct in your assumption, there were two positions of droop: 5 deg's for taxi/take-off and low speed flight and 12.5 deg's for landing. The glazed visor retracted into the nose and could ONLY be raised once the nose was fully up, and had to be stowed before the nose could move down. There were 2 emergency nose lowering sysyems; one using stby (Yellow) hydraulics and a free-fall system. Free-fall would drop the nose all the way to 12.5 deg's, the visor free falling into the nose also.
Stupid, you? no way!! (Besides, I'm Mr Stupid of the aviation world, that's my title
). The thing is, out here in the world of flying machines, there are almost an infinite number of questions (and hopefully answers too). This applies to just about all aircraft from the Wright Flyer up!!.
Keep asking away, there are so many of us Concorde 'nuts' out here who are more than happy to help out/bore the socks off you.
Fuel burns: The problem was that when flying slow/taxying, Concorde was an extreme gas guzzler, even when idling each engine burnt around 1.1 tonnes/hour (so every 15 minutes after push back meant over a tonne gone). A typical taxi fuel would be around 1.4/1.5 tonnes, depending on the runway in use on the day. I'd have to leave it to some of my pilot/F/E friends to remember some of the specific fuel burns after take off etc, but I can at least give you some interesting consumption figures:
At the beginning of the take off roll, each engine would be burning around 21 tonnes/hour. (Made up of around 12 T/Hr dry fuel (Fe) and 9T/Hr afterburner (reheat to us Brits) fuel (Fr). As Fr was scheduled against Fe, as a function of inlet total temp (T1) by the time V2 was reached (around 220 KTS) the rising T1 has pushed the total fuel flow (Ft) up to a staggering 25 tonnes/hour/engine. As i've pointed out before in previous topics, although the afterburner only gave us a 17% improvement in take off thrust, it was responsible for around an 80% hike in fuel burn. (Hence that is whay it was only used sparingly). However when reheat was used for transonic acceleration, it used a dramatically reduced schedule (roughly a 60% rise in fuel flow) , so it was not quite as scary. The afterburner would be lit at the commencement of the acceleration (0.96 Mach) and cancelled completely at 1.7 Mach. After this time the aircraft would accelerate on dry power only up to mach 2 and beyond. (The cooler the temperature the quicker the time to Mach 2). On an ISA+ day, it sometimes felt that the aircraft was flying through cold porridge, and could take quite a while to get to Mach 2 after reaheat cancellation, where as on a nice ISA - day, she would go like a bat out of hell, and the AFCS would have to jump in to prevent overspeeds.
Before I hit some more numbers, let me say that with Concorde, TOC = TOD!! After reheat cancellation at Mach 1.7, the aircraft would be at FL 430. The aircraft would climb at an IAS of 530 KTS until Mach 2 was reached at fractionally over FL500. From then on the aircraft would cruise/climb as fuel was burnt, up to a maximum of FL600. On warmish days (eg. the North Atlantic) TOD would typically be around FL570-580. On a cool day (the lowes temperatures would of course be reached in the more tropical regions; the LGR-BGI sector encountered this), FL 600 would be reached easily and she would love to climb some more. BUT, the aircaft was only certificated to 60,000' with passengers onboard, for decompression emergency descent time reasons, and so we were stuck with it. The pity is of course, the fuel burn would have been improved, but we never were able to take advantage of this. On test flights however, the aircraft would routinely zoom climb to FL 630. On her maiden flight, aircaft 208 (G-BOAB) reached an altitude of 65000'; the highest recorded Concorde altitude was on one of the French development aircraft, which achieved 68,000'. On a technical point, the analog ADC's were 'only' calibrated to 65,000'.
Anyway, back to some figues; at Mach 2, 50,000', the typical fuel burn per engine would be around 5 tonnes/hour, falling to around 4.2 tonnes/hour at 60,000'.
THE NOSE You are quite correct in your assumption, there were two positions of droop: 5 deg's for taxi/take-off and low speed flight and 12.5 deg's for landing. The glazed visor retracted into the nose and could ONLY be raised once the nose was fully up, and had to be stowed before the nose could move down. There were 2 emergency nose lowering sysyems; one using stby (Yellow) hydraulics and a free-fall system. Free-fall would drop the nose all the way to 12.5 deg's, the visor free falling into the nose also.
Last edited by M2dude; 19th Aug 2010 at 12:40 . Reason: mistooks
20th Aug 2010, 22:55
permalink Post: 38
Quote:
|
Originally Posted by
Nick Thomas
Once again thanks M2dude and ChristiaanJ for such interesting answers.
|
Quote:
| Would it be too much of an exaggeration to say that Concorde provided the sound technical foundations on which Airbus have now so successfully built? |
As an example in my particular field, you have to be an expert to distinguish the Concorde ADI (Attitude Director Indicator) and HSI (Horizontal Situation Indicator) - the two big central instruments on the pilot's and copilot's panel - from those on the first Airbus, the A300, or the early A310s. Apart from a couple of lights and buttons, they were the same, and the innards were pretty well identical.
And a lot of the technology in the AFCS (Automtic Flight Control System, i.e., the autopilots, etc.) was also virtually indistinguishable (the circuitry was obviously different... an A300 did not do Mach2).
But even more than the technical foundations, Concorde also laid the foundations for an effective and successful international cooperation in aircraft design, development and production.
We learned a tremendous amount from Concorde... Airbus might still have happened without Concorde, but it certainly would have happened years later.
Quote:
| Am I right in saying that Concorde was the first fly by wire commerical plane? |
The one difference with "modern" FBW commercial planes (such as the A320) is that Concorde still did have a mechanical back-up for when all else failed.
At the time, there was still a doubt about all these new-fangled elektriks replacing good old rods and cables, so when you look under the floor in a Concorde, the rods and cables are still there.
But apart from tests and training for emergencies, essentially they were never used.
21st Aug 2010, 10:47
permalink Post: 44
Biggles78
Sorry Biggles78, I'd forgotten to answer your CofG query, so here we go: CofG was a really critical parameter on Concorde, being a delta, with no tailplane made it more so at take off speeds, and as we've previously said, was how we trimmed the aircraft for supersonic flight. CG was expressed as a percentage of the aerodynamic chord line. To get indication of CG you needed to know the mass of fuel in each tank; easy, from the FQI system. You needed to know the moment arm of each tank, (fixed of course). You then needed the zero fuel weight (ZFW) and zero fuel CG (ZFCG); these were manually input into the CG computers by the F/E, from load control data. The final parameter you needed was total fuel weight, again easy from the FQI system.
The 'normal' T/O CG was 53.5%, but in order to increase fuel weight (and hence range) an extra 'bump' was enabled to allow a max T/O CG of 54%. (CG was indicated on a linear gauge, with forward and aft limit 'bugs' either side of the needle. These bugs would move as a function of Mach and at the lower end of the speed range, A/C weight also). As the A/C accelerated, the limit bugs would move rearwards (with of course the rearward shifting centre of pressure) and so the fuel would be moved from the two front trim tanks 9 & 10 to the rear tank. 11. Once tank 11 reached it's preset limit (around 10 tonnes), the remainder of the 'front' fuel would automatically over-spill into tanks 5 & 7. (Once the fuel panel was set up, the whole process was controlled with a single switch). At Mach 2, the CG would be around 59%, the whole rearwards shift being in the order of 6'. As we said before, the 'final' CG could be tweaked to give us a 1/2 degree down elevon, for minimum drag.
I really hope this helps Biggles78.
Guys, back to the Airbus thing; My friend ChristiaanJ gave some really accurate insights, (he always does) but there is another legacy that carries on the this day; some of the audio warning tones were COPIED from Concorde into Airbus. (For example, the A/P disconnect audio is identical). I think this is great, and gives 'our' aircraft a lasting everyday legacy.
As far as the fly by wire goes, Concorde had a relatively simple analog system, with little or no envelope protection (Except at extreme angles if attack). As has been previously poted before, production series test aircraft 201, F-WTSB, pioneered the use of a sidestick within a new digital fly by wire Controlled Conviguration Vehicle sytem, with envelope protection and attitude rate feedback. (This evolved into the superb system known and loved by the Airbus community). It is a really bizaar twist of fate that the Concorde FBW system has more mechanical similarities to the system used in the B777 than Airbus. (Mechanically similar at the front end, with an electric backdrive system moving the column in A/P mode; Concorde being backdriven by a hydraulic relay jack).
As a final piece of irony; the Primary Flight Control Computers on the B777 are designed and built by GEC Marconi Avionics in Rochester Kent, now BAe Systems. This is the same plant where Elliot (becoming Marconi and finally GEC Marconi Avionics) developed and built the UK half of the AFCS computers. Isn't this aviation world strange?
Galaxy Flyer
Your inputs here are great, and I'm sure appreciated by all. (I assume from your name that you were a C5A pilot. While I was in the RAF on C-130's, our Lockheed rep' used to supply us all with company magazines, that were full of stuff on this new (it was then) giant of the sky. I fell in love with it there and then).
Anyway, back to Conc': The decel' positions were carefully worked out and adhered to; the aim was to be subsonic to within (I think) 50 nm of the east coast. I'll wait for one of my Concorde pilot friends to confirm that here, but i think I'm correct. I do have a fond memory of one flight out of JFK; we were temporarily 'held' by Boston ATC to Mach 1.6 (and at around FL440) because of an Air France Concorde heading for JFK. We saw this guy above us, at around FL580 on a near reciprical , doing Mach 2, screaming straight over the top of us. We were excited by this amazing spectacle, and so were the AF crew over the VHF ('you never boomed us, did we boom you?'). But the most excited person of all was this guy in Boston ATC. ('I've never seen anything like it guys, your two blips whistled over each other on my my screen like crazy').
Stliton
As far as the F/D noise levels were concerned, once the nose and visor were raised, it was as if someone had switched off the noise
. The main source of noise up there was just the equipment cooling, and that was not bad either. It was, in my view, little noisier up than most subsonics. (But not the 744, where you are so far away from all the racket
).
Ozgrade3
You're making us blush here; thanks for your comments, I think we are just trying to share some of our experiences (and 'bit's we've picked up over the years).
From my perspective, I did write some stuff used by our pilots, AF even got a copy or two I think.
Quote:
Last one for this post. What was the CoG range? I remember when I started flying and finally twigged to what it was all about that the PA28 had something like a 5" from the forward to aft limit and was massively surprised by the small "balance point". Trim tanks on 1 aeroplane I flew would have been most welcome.
|
The 'normal' T/O CG was 53.5%, but in order to increase fuel weight (and hence range) an extra 'bump' was enabled to allow a max T/O CG of 54%. (CG was indicated on a linear gauge, with forward and aft limit 'bugs' either side of the needle. These bugs would move as a function of Mach and at the lower end of the speed range, A/C weight also). As the A/C accelerated, the limit bugs would move rearwards (with of course the rearward shifting centre of pressure) and so the fuel would be moved from the two front trim tanks 9 & 10 to the rear tank. 11. Once tank 11 reached it's preset limit (around 10 tonnes), the remainder of the 'front' fuel would automatically over-spill into tanks 5 & 7. (Once the fuel panel was set up, the whole process was controlled with a single switch). At Mach 2, the CG would be around 59%, the whole rearwards shift being in the order of 6'. As we said before, the 'final' CG could be tweaked to give us a 1/2 degree down elevon, for minimum drag.
I really hope this helps Biggles78.
Guys, back to the Airbus thing; My friend ChristiaanJ gave some really accurate insights, (he always does) but there is another legacy that carries on the this day; some of the audio warning tones were COPIED from Concorde into Airbus. (For example, the A/P disconnect audio is identical). I think this is great, and gives 'our' aircraft a lasting everyday legacy.
As far as the fly by wire goes, Concorde had a relatively simple analog system, with little or no envelope protection (Except at extreme angles if attack). As has been previously poted before, production series test aircraft 201, F-WTSB, pioneered the use of a sidestick within a new digital fly by wire Controlled Conviguration Vehicle sytem, with envelope protection and attitude rate feedback. (This evolved into the superb system known and loved by the Airbus community). It is a really bizaar twist of fate that the Concorde FBW system has more mechanical similarities to the system used in the B777 than Airbus. (Mechanically similar at the front end, with an electric backdrive system moving the column in A/P mode; Concorde being backdriven by a hydraulic relay jack).
As a final piece of irony; the Primary Flight Control Computers on the B777 are designed and built by GEC Marconi Avionics in Rochester Kent, now BAe Systems. This is the same plant where Elliot (becoming Marconi and finally GEC Marconi Avionics) developed and built the UK half of the AFCS computers. Isn't this aviation world strange?
Galaxy Flyer
Your inputs here are great, and I'm sure appreciated by all. (I assume from your name that you were a C5A pilot. While I was in the RAF on C-130's, our Lockheed rep' used to supply us all with company magazines, that were full of stuff on this new (it was then) giant of the sky. I fell in love with it there and then).
Anyway, back to Conc': The decel' positions were carefully worked out and adhered to; the aim was to be subsonic to within (I think) 50 nm of the east coast. I'll wait for one of my Concorde pilot friends to confirm that here, but i think I'm correct. I do have a fond memory of one flight out of JFK; we were temporarily 'held' by Boston ATC to Mach 1.6 (and at around FL440) because of an Air France Concorde heading for JFK. We saw this guy above us, at around FL580 on a near reciprical , doing Mach 2, screaming straight over the top of us. We were excited by this amazing spectacle, and so were the AF crew over the VHF ('you never boomed us, did we boom you?'). But the most excited person of all was this guy in Boston ATC. ('I've never seen anything like it guys, your two blips whistled over each other on my my screen like crazy').
Stliton
As far as the F/D noise levels were concerned, once the nose and visor were raised, it was as if someone had switched off the noise
. The main source of noise up there was just the equipment cooling, and that was not bad either. It was, in my view, little noisier up than most subsonics. (But not the 744, where you are so far away from all the racket
).
Ozgrade3
You're making us blush here; thanks for your comments, I think we are just trying to share some of our experiences (and 'bit's we've picked up over the years).
From my perspective, I did write some stuff used by our pilots, AF even got a copy or two I think.
Last edited by M2dude; 21st Aug 2010 at 13:01 . Reason: couple of corrections; this guy can't spell
21st Aug 2010, 21:03
permalink Post: 53
Ozegrade3, Biggles78 and all,
I agree, the more of the history that we can write down somewhere, the better....
Just look at the "Did You Fly the Vulcan?" thread here on PPRuNe....
A chance remark by M2dude reminded me of something I meant to write about sometimes... and that has barely been mentioned in the various Concorde stories.
It's the huge gap between the prototypes on the one hand, and the pre-production and production aircraft on the other hand.
It's not just the visor, or the shorter tail.
In my own "field", the AFCS (autopilot, etc.), there was not a lot of similarity between the prototypes and their successors.
The prototypes were "proof-of-concept", designed in the early to mid 1960s.
The pre-production aircraft were designed in the end of the '60s and already close to the production aircraft in most respects.
Some of this difference was due to the very sudden and rapid evolution in electronic technology, with the arrival of the integrated circuit in particular.
The microprocessor - in a way just a large integrated circuit - didn't arrive in time... I don't think there was a single microprocessor on board Concorde until the days that they had to fit TCAS (in the '90s, IIRC).
I'll have to see how to do it.... maybe write it off-line and post snippets on here, then move it into a blog or suchlike?
I agree, the more of the history that we can write down somewhere, the better....
Just look at the "Did You Fly the Vulcan?" thread here on PPRuNe....
A chance remark by M2dude reminded me of something I meant to write about sometimes... and that has barely been mentioned in the various Concorde stories.
It's the huge gap between the prototypes on the one hand, and the pre-production and production aircraft on the other hand.
It's not just the visor, or the shorter tail.
In my own "field", the AFCS (autopilot, etc.), there was not a lot of similarity between the prototypes and their successors.
The prototypes were "proof-of-concept", designed in the early to mid 1960s.
The pre-production aircraft were designed in the end of the '60s and already close to the production aircraft in most respects.
Some of this difference was due to the very sudden and rapid evolution in electronic technology, with the arrival of the integrated circuit in particular.
The microprocessor - in a way just a large integrated circuit - didn't arrive in time... I don't think there was a single microprocessor on board Concorde until the days that they had to fit TCAS (in the '90s, IIRC).
I'll have to see how to do it.... maybe write it off-line and post snippets on here, then move it into a blog or suchlike?
22nd Aug 2010, 01:47
permalink Post: 56
Biggles78
You are right on the button. Under NORMAL circumstances, Concorde never flew supersonically in level flight. You would always follow the Vmo bug on the ASI during the supersonic climb. (The ASI pointer actually nudged into the bug; it was a beautiful design). Initially this would be at a constant Vc of 400 kts, the 400 KT segment then went off towards 530 KTS as you climbed. You then 'stuck' to 530 knots until a fraction over 50,000', when 530 KTS became Mach 2. You would then continue the climb at between Mach 2 and around Mach 2.02, depending on the temperature of the day. (the colder the temperature, the faster you tended to fly). There was an extremely complex AFCS mode for the supersonic climb, that I promise to cover in anaother post.
So yes, on the whole, TOC did equal TOD.
The 'subsonic climb' wasn't quite as you thought; you'd normally subsonic climb to FL280, staying there (at Mach 0.95) until the acceleration point. Mach 0.95 was 'subsonic cruise'. But you were on the right track.
Oh, and NOPE, they never boomed us either
Nick Thomas
Keeping the powerplants as separate as possible was a major design headache, but generally they were just that; there was a titanium centre wall between the two engines and a really substantial heatshield above the engine also, to protect the wing above. To give you an idea how all this worked in practice, in 1980 G-BOAF, flying at Mach 2 between JFK and LHR had a major failure of one of the engines, caused by a defective material ingot used in the forging of one of the 1st stage LP compressor blades; which was subsequently shed. (The analysis done by Rolls Royce ensured that no such incident ever happened again in the life of Concorde). The resulting mayhem terminated in a large amount of engine debris flying around, and a titanium fire burning in the engine bay also. The aircraft however decelerated and landed at Shannon safely. On inspection, although there was extensive damage found in the engine bay, the adjacent engine was completely unmarked, protected by the titanium centre wall, and more importantly, when the heat shield werer removed, the wing was found to be completely undamaged!
The only problem you ever had with the dual nacelle arrangement was if you had an engine surge above Mach 1.6 (These were relatively rare, but could happen with an engine or intake control system malfuntion). If one engine surged, the other would surge in sympathy, because of the shock system being expelled from one intake severely distorting the airflow into it's neighbour. These surges were loud, quite scary (to the crew that is, most passengers never noticed much), but in themselves did no damage at all. Delicate movement of the throttles (employed during the subsequent surge drill) would invariably restore peace and harmony again to all. (The intake on Concorde was self-starting, so no manual movement of the intake variable surfaces should be needed in this event). After this was over, normal flying was resumed again As I said before, these events were relatively rare, but when they did occur, they would be dealt with smartly and professionally; the engine and intake structure being undamaged. (Post surge inspetion checks were always carried out on the ground after an event, on both engine and intake, but nothing much was EVER found).
The reduction of fuel flow as you climbed was quite interesting. Although the throttles would be 'at the wall' (dry power remember), the electronic control system was constantly winding fuel off as a function of Static Air Temperature, as well as falling Total Pressure. The system was always 'tweaking' as you climbed, and you only used as much fuel as you really needed to stay at Mach 2. There were various ratings that would also be manually selected at various phases of flight; each rating change 'detuned' the engine slightly, so yes, you did not run the engine when flying fast at anywhere near the levels you did at lower speeds/altitudes. The engine final ratings were changed from 'Climb' to 'Cruise' manually at FL 500, just as you hit Mach 2).
Quote:
| Am I right or even slightly so in thinking that cruise climb and cruise descent was the flight and there was minimal actual level cruise in the "pond" crossing? |
So yes, on the whole, TOC did equal TOD.
The 'subsonic climb' wasn't quite as you thought; you'd normally subsonic climb to FL280, staying there (at Mach 0.95) until the acceleration point. Mach 0.95 was 'subsonic cruise'. But you were on the right track.
Oh, and NOPE, they never boomed us either
Nick Thomas
Quote:
| If an engine had a fire or an explosive failure; it would seem on the face of it that the adjacent engine could easily be affected. As everything on Concorde has a sound technical reason. I have been wondering what that reason or reasons was? and also if there was any inbuilt dividing protection between engines on the same wing? |
The only problem you ever had with the dual nacelle arrangement was if you had an engine surge above Mach 1.6 (These were relatively rare, but could happen with an engine or intake control system malfuntion). If one engine surged, the other would surge in sympathy, because of the shock system being expelled from one intake severely distorting the airflow into it's neighbour. These surges were loud, quite scary (to the crew that is, most passengers never noticed much), but in themselves did no damage at all. Delicate movement of the throttles (employed during the subsequent surge drill) would invariably restore peace and harmony again to all. (The intake on Concorde was self-starting, so no manual movement of the intake variable surfaces should be needed in this event). After this was over, normal flying was resumed again As I said before, these events were relatively rare, but when they did occur, they would be dealt with smartly and professionally; the engine and intake structure being undamaged. (Post surge inspetion checks were always carried out on the ground after an event, on both engine and intake, but nothing much was EVER found).
Quote:
| Would I also be right to assume that the max power delivered by the engines would reduce at altitude, thus even if the engines were run at near to available max power at high altitude it would be no way near the max power at lower levels? |
24th Aug 2010, 12:02
permalink Post: 90
MEMORIES
Like so many in the Concorde family, I have millions, I'd like to share a couple here. I remember at Fairford in mid 1974, a CAA test pilot (I honestly forget the gentleman's name) was taking the British pre-production A/C 101 (G-AXDN) for a special test flight. The reason that this flight was so special was that for the first time, the CAA were going to do an acceptance flight trial of the brand new digital air intake system. This revolutionary system had been retro fitted to 101 barely a year earlier, and being a brand new (and totally unique, in electronics terms) system had been plagued with teething troubles. It was quite reasonable for any airworthiness authority to have serious misgivings about any system that was going to wave great big metal lumps around in front of the engine compressor face, and that if only a few degrees out from the commanded position out could cause the engine to 'backfire' etc.
So anyway, 101 took off and disappeared into the very blue sky and we waited, and waited, AND WAITED. (I'd only left the RAF and joined the project a few months previously, and did not want my new association with this amazing aircraft to end). I was biting my nails, drinking coffee, losing my hair... (without the help of M2V
). Anyway after about 2 1/2 hours the aircraft returned to Fairford, and everybody crowds around the crew for the debrief. A very stern faced CAA pilot looked at us all, broke into a grin and said "as far as I'm concerned gentlemen, you've got yourselves an airliner". At that point the room was a study of total happiness, blessed relief, and a need to go to the loo..... But from my point of view, I will remember those words forever.
101, which now resides at the Imperial War Museum Duxford was the fastest Concorde ever. She achieved Mach 2.23, which was an incredible irony, as Concorde can trace a large part of it's developement history back to the BAC 223, proposed SST.
As far as flying memories go, I just don't know where to start; My first ever Concorde flight was in November 1976, out of Fairford on a pre-delivery test flight on G-BOAD. (Now sadly bobbing up and down on the Hudson, next to the USS Intrepid). I was staggered how fast and high we flew (Mach 2.08, FL580). Most of my flying up to that date had been in C-130's in the RAF, at around 340 KTS and FL300; Concorde also being infinately quiter in flight than the good old Herc'. I remember a BA QA guy showing me how I could touch the skin of the aircraft at Mach 2 (You reached behind a door busstle flap, moved your hand through some insulation until you felt bare metal). OUCH!! it was hot, very hot.
But I think one of my most memorable flight memories was aboard G-BOAG, (now residing in the Boeing Museum of Flight in Seattle) returning from BKK, having stopped off to refuel in BAH. We were forced to fly subsonic over Saudi, and got caught in this amazing electrical storm, There was St Elmo's fire cracking and bubbling all over the visor panels, but just as incredible was the long blue electrical discharge coming off of the nose probe; it seemed to extend about 50' in front of the aircraft. The crime was, none of us on the F/D had a camera. Every time I bump into the captain on that day (are you reading this Ian?), we go back to remonissing about that incredible flight. Also, later on the same sector, after we had decelerated to subsonic cruise again, this time flying up the Adriatic, we had another fascinating sight: It was getting quite dark now, and here we were, travelling at Mach 0.95 at FL290, when above us was all this Mach 0.8 ish traffic at around FL330-350. All we could see were all these navigation and ant-coll' lights above us, seemingly travelling backwards. It was quite a sight. On the original BAH-BKK sector a week earlier, we flew through some of the coldest air I'd ever seen; The air was at ISA -25, and at Mach 2 our TAT was only about 85 deg's C. (You could feel the difference too; the cabin windows felt only warm-ish to the touch). The upside also of all this was that your fuel burn was much lower than usual. (The only downside of course is that your TAS is a little lower). Rolls Royce did some analysis on the flight, and were amazed at how well the propulsion systems coped with some of the temperature sheers that we encountered, sometimes 4 to 5 deg's/second. They said that the prototype AFCS had been defeated by rises of only 0.25 deg's/second ).
Not meaning to go off onto a (yet another) tangent; Negative temperature shears, very common at lower lattidudes, always plagued the development aircraft; you would suddenly accelerate, and in the case of a severe shear, would accelerate and accelerate!! (Your Mach number, quite naturaly, suddenly increased with the falling temperature of course, but because of the powerplant suddenly hitting an area of hyper-efficiencey, the A/C would physically accelerate rapidly, way beyond Mmo). Many modifications were tried to mitigate the effects of severe shears, in the end a clever change to the intake control unit software fixed it. (Thanks to this change the production series A/C would not be capable of level flight Mach numbers of any more than Mach 2.13, remembering that Mmo was set at 2.04).
There was one lovely story, involving the Shah of Iran, having one of MANY flights in a developmment aircraft. The aircraft encounterd quite a hefty series of temperature shears that plagued havoc with some Iranian F4's that were attempting to close on the Concorde, to act as an escort for the Shah. (or so the strory goes). I'm still trying to picture these F4's, on full afterburner trying to get close to a Concorde cruising away on dry power). It is said that the F4's were having such difficulties, due to their relatively crude powerplant, coping with the temperature changes, that the Concorde was ordered to slow down, 'so the escorting F4's could catch up'!! True or not, it is part of Concorde folklore.
Dude
Like so many in the Concorde family, I have millions, I'd like to share a couple here. I remember at Fairford in mid 1974, a CAA test pilot (I honestly forget the gentleman's name) was taking the British pre-production A/C 101 (G-AXDN) for a special test flight. The reason that this flight was so special was that for the first time, the CAA were going to do an acceptance flight trial of the brand new digital air intake system. This revolutionary system had been retro fitted to 101 barely a year earlier, and being a brand new (and totally unique, in electronics terms) system had been plagued with teething troubles. It was quite reasonable for any airworthiness authority to have serious misgivings about any system that was going to wave great big metal lumps around in front of the engine compressor face, and that if only a few degrees out from the commanded position out could cause the engine to 'backfire' etc.
So anyway, 101 took off and disappeared into the very blue sky and we waited, and waited, AND WAITED. (I'd only left the RAF and joined the project a few months previously, and did not want my new association with this amazing aircraft to end). I was biting my nails, drinking coffee, losing my hair... (without the help of M2V
). Anyway after about 2 1/2 hours the aircraft returned to Fairford, and everybody crowds around the crew for the debrief. A very stern faced CAA pilot looked at us all, broke into a grin and said "as far as I'm concerned gentlemen, you've got yourselves an airliner". At that point the room was a study of total happiness, blessed relief, and a need to go to the loo..... But from my point of view, I will remember those words forever.
101, which now resides at the Imperial War Museum Duxford was the fastest Concorde ever. She achieved Mach 2.23, which was an incredible irony, as Concorde can trace a large part of it's developement history back to the BAC 223, proposed SST.
As far as flying memories go, I just don't know where to start; My first ever Concorde flight was in November 1976, out of Fairford on a pre-delivery test flight on G-BOAD. (Now sadly bobbing up and down on the Hudson, next to the USS Intrepid). I was staggered how fast and high we flew (Mach 2.08, FL580). Most of my flying up to that date had been in C-130's in the RAF, at around 340 KTS and FL300; Concorde also being infinately quiter in flight than the good old Herc'. I remember a BA QA guy showing me how I could touch the skin of the aircraft at Mach 2 (You reached behind a door busstle flap, moved your hand through some insulation until you felt bare metal). OUCH!! it was hot, very hot.
But I think one of my most memorable flight memories was aboard G-BOAG, (now residing in the Boeing Museum of Flight in Seattle) returning from BKK, having stopped off to refuel in BAH. We were forced to fly subsonic over Saudi, and got caught in this amazing electrical storm, There was St Elmo's fire cracking and bubbling all over the visor panels, but just as incredible was the long blue electrical discharge coming off of the nose probe; it seemed to extend about 50' in front of the aircraft. The crime was, none of us on the F/D had a camera. Every time I bump into the captain on that day (are you reading this Ian?), we go back to remonissing about that incredible flight. Also, later on the same sector, after we had decelerated to subsonic cruise again, this time flying up the Adriatic, we had another fascinating sight: It was getting quite dark now, and here we were, travelling at Mach 0.95 at FL290, when above us was all this Mach 0.8 ish traffic at around FL330-350. All we could see were all these navigation and ant-coll' lights above us, seemingly travelling backwards. It was quite a sight. On the original BAH-BKK sector a week earlier, we flew through some of the coldest air I'd ever seen; The air was at ISA -25, and at Mach 2 our TAT was only about 85 deg's C. (You could feel the difference too; the cabin windows felt only warm-ish to the touch). The upside also of all this was that your fuel burn was much lower than usual. (The only downside of course is that your TAS is a little lower). Rolls Royce did some analysis on the flight, and were amazed at how well the propulsion systems coped with some of the temperature sheers that we encountered, sometimes 4 to 5 deg's/second. They said that the prototype AFCS had been defeated by rises of only 0.25 deg's/second ).
Not meaning to go off onto a (yet another) tangent; Negative temperature shears, very common at lower lattidudes, always plagued the development aircraft; you would suddenly accelerate, and in the case of a severe shear, would accelerate and accelerate!! (Your Mach number, quite naturaly, suddenly increased with the falling temperature of course, but because of the powerplant suddenly hitting an area of hyper-efficiencey, the A/C would physically accelerate rapidly, way beyond Mmo). Many modifications were tried to mitigate the effects of severe shears, in the end a clever change to the intake control unit software fixed it. (Thanks to this change the production series A/C would not be capable of level flight Mach numbers of any more than Mach 2.13, remembering that Mmo was set at 2.04).
There was one lovely story, involving the Shah of Iran, having one of MANY flights in a developmment aircraft. The aircraft encounterd quite a hefty series of temperature shears that plagued havoc with some Iranian F4's that were attempting to close on the Concorde, to act as an escort for the Shah. (or so the strory goes). I'm still trying to picture these F4's, on full afterburner trying to get close to a Concorde cruising away on dry power). It is said that the F4's were having such difficulties, due to their relatively crude powerplant, coping with the temperature changes, that the Concorde was ordered to slow down, 'so the escorting F4's could catch up'!! True or not, it is part of Concorde folklore.
Dude
Last edited by M2dude; 24th Aug 2010 at 15:31 . Reason: spelling (again) :-(
24th Aug 2010, 15:25
permalink Post: 93
M2dude
,
Thanks for bringing up the story of the temperature shears at low latitudes, saves me some explaining !
The phenomenon was not really "discovered" until the route proving started.
As you say, it meant abrupt changes in Mach and Tt.
Since the pitch autopilot in, say, 'Mach Hold', had only one way to cope with those changes : pitching up or pitching down, this resulted in abrupt climb and descent manoeuvres that were totally inacceptable.
It was not only fixed by modifiying the intake controls.... !
It also led to a fairly major mod in the AFCS, by bringing the auto-throttle into the loop.
Instead of letting the pitch A/P take the aircraft into a zoom climb to try and stay within the "speed limits", it woold be the autothrottle pulling the throttles back.
After a fair amount of flight tests, this became the final form of the 'Max Cruise' mode.
I know... I should have kept a diary.
All this happened 35 years ago, so I can't put exact dates, or even specific aircraft, into the story. At least I still have some Concorde doc, that at times allows me to refresh my memory.
But one thing stayed in my memory over the years ...
The initial A/P+A/T 'Max Cruise' mod meant a major modification of the autothrottle computers. One of the circuit boards in particular was totally "butchered" on-site (Fairford), with well over a hundred track cuts and new wire links, not to mention the number of component changes (to give an idea to the 'experts', these were double-sided PCBs of about 15x20cm).
We got the job done (4 boards : 2 boards per computer, 2 computers), got the computers tested and on the aircraft. Knowing full well how easy it was to introduce faults and problems during such a modification (a dud solder joint could be enough), we expected to see them back within days, or at least within a few flights.
Well..... those computers left the lab with each about a thousand hours "on the clock" (they have little elapsed-time counters that indicated hours under power, NOT flight hours).
The first time we saw them back (for a minor mod, not a fault), both clocks showed over 10,000 hours !
Ah, those were the days
CJ
Thanks for bringing up the story of the temperature shears at low latitudes, saves me some explaining !
The phenomenon was not really "discovered" until the route proving started.
As you say, it meant abrupt changes in Mach and Tt.
Since the pitch autopilot in, say, 'Mach Hold', had only one way to cope with those changes : pitching up or pitching down, this resulted in abrupt climb and descent manoeuvres that were totally inacceptable.
It was not only fixed by modifiying the intake controls.... !
It also led to a fairly major mod in the AFCS, by bringing the auto-throttle into the loop.
Instead of letting the pitch A/P take the aircraft into a zoom climb to try and stay within the "speed limits", it woold be the autothrottle pulling the throttles back.
After a fair amount of flight tests, this became the final form of the 'Max Cruise' mode.
I know... I should have kept a diary.
All this happened 35 years ago, so I can't put exact dates, or even specific aircraft, into the story. At least I still have some Concorde doc, that at times allows me to refresh my memory.
But one thing stayed in my memory over the years ...
The initial A/P+A/T 'Max Cruise' mod meant a major modification of the autothrottle computers. One of the circuit boards in particular was totally "butchered" on-site (Fairford), with well over a hundred track cuts and new wire links, not to mention the number of component changes (to give an idea to the 'experts', these were double-sided PCBs of about 15x20cm).
We got the job done (4 boards : 2 boards per computer, 2 computers), got the computers tested and on the aircraft. Knowing full well how easy it was to introduce faults and problems during such a modification (a dud solder joint could be enough), we expected to see them back within days, or at least within a few flights.
Well..... those computers left the lab with each about a thousand hours "on the clock" (they have little elapsed-time counters that indicated hours under power, NOT flight hours).
The first time we saw them back (for a minor mod, not a fault), both clocks showed over 10,000 hours !
Ah, those were the days
CJ
24th Aug 2010, 22:49
permalink Post: 101
ChristiaanJ
aaah yes, Max Climb/Max Cruise modes. I'd not forgotten this my friend, I was going to say a few words about that in a future post, but maybe we can do that now. (And I'd love to hear more of your comments on this here too, ChristiaanJ). The intake and autopilot modifications were in a way complimentary it's true, but really dealt with separate problems, at least in my view:
The intake control unit software change (a change to the control law that limited engine N1 as a function of intake local Mach number, Mo, and inlet total temperature, T1) was able to put an absolute limit on aircraft achievable Mach number during Mmo overshoots, but it would not PREVENT Mmo overshoots occurring altogether, it was more of a safety brake. This particular overspeed problem manifested itself well before route proving, and in fact the intake system 'fix' resulted in the Thrust Auto Reduce System being deleted, electronic control boxes and all. The TAR system was fitted on all development aircraft equiped with the digital intake system, and it tried (in vain) to limit extreme Mach overshoots. The production aircraft retained the TAR wiring and locked out circuit breakers, as well as two vacant spaces on the electronic racks. The prime reason for all these efforts were that some of the rapid excessive Mach overshoots quite often drove the intake into surge; the modification to this N1 limiter control enabled engine mass flow to be controlled in such a way that these surges could be prevented during temperature shears. The aircraft Mach limit was an extremely useful fringe benefit.
The AFCS mode change from what was Max Op and Max Op Soft (always loved that name) to Max Climb/Max Cruise was at a stroke able to deal with the regular Mmo overspeeds that kept on occuring during, as you say, the route proving trials of 1975, when British aircraft G-BOAC and the French aircrfraft F-BTSD carried out pre entry into service evaluation flights, SD sadly was the aircraft that was tragically lost at Gonez in July 2000). The Max Climb/Max Cruise AFCS mode combo is a mode like no other that I've personally seen before or since anywhere, (it for instance resulted an elsewhere taboo; an autopilot and an autothrotte working together IN A SPEED MODE).
This problem encountered primarily at lower lattitudes, (for example, G-BOAC doing route proving flights out of Singapore), occurring initially as the aircraft reached Mach 2. It was termed 'the insurmountable problem', but the AFCS designers (such as ChristiaanJ) fortunately did not have 'insurmountable problems' in their vocabulary. The issue was that the aircraft would have been climbing rapidly at Vmo of 530 KTS, with throttles at the gate as usual, At exactly 50,189' we hit what was known as 'the corner point' in the flight envelope, where 530 KTS IAS equated to Mach 2 exactly. Max Op mode would then 'let go' of the Vmo segment, and try and control the aircraft to Mach 2. (As the aircraft climbed, Vmo itself would progreesively decrease in order to equate to Mmo, or 2.04 Mach). But in very cold conditions, the aircraft still 'wanting' to accelerate, and the simple Max Op/Max Op Soft modes just could not cope with gentle pitch changes alone. The problem became even bigger during the cruise/climb when severe temperature shears occured, and routinely regular Mmo exceedences occured. Something had to be done, and something WAS done and how; enter Max Climb/Max Cruise. It was really a classic piece of design, where the aircraft would do the initial supersonic climb in Max Climb mode. This mode itself was relatively simple, in that it was more or less a Vmo -Vc hold mode. That meant that the difference at selection between indicated airspeed, Vc and Vmo would be maintained, with a vernier datum adjust to this being available. In practice this mode was selected pretty much at Vmo, so datum adjusting was not always required. Now comes the clever part; the autothrottle, this would operate in standy mode at this point, just waiting there doing nothing, with the throttles at maximum as before. So the aircraft would now climb as Vmo increased to 530 KTS, and then following a now constant Vmo of 530 KTS until the magic 'corner point' (51, 189' remember). Now all hell would break loose; the mode would automatically change to Max Cruise, the autothrottle would also be automaically selected to Mach Hold mode (initially datumed here to Mach 2) and the throttles would retard, attempting to hold this Mach 2 datum, and the autopilot is commands a 'fly up' signal, over a 20 second lag period to 600'/minute. Now comes an even cleverer (?) part; the autothrottle Mach Hold datum is gradually increased over a 100 second period towards Mach 2.02, and so in stable conditions the throttles would now gradually increase again until they once more reach the maximum limit. At this point, the autothrottles now come out of Mach Hold mode and back into the waiting in the wings standby mode. The autopilot would now cancel it's 600' fly up, demand, returning to a datum of Mach 2. There was a little more complexity built in also, where the difference between the 'commanded' and actual vertical speeds offset the autoplilot Mach 2 datum. This would apply whether the autothrottle had cut in (+600'/min demand) or with the throttles back at maximum (0'/minute demand. A positive climb error tweaked the cruise Mach up slightly, a negative error (eg. in a turn) the converse was true. The effect of all of this complexity was that the aircraft itself could 'scan' until it settled at a point where the throttles could be at maximum, and the speed between Mach 2 and 2.02. On the North Atlantic, with warmer ISA temperatures, there was usually just the initial routine with the autothrottle as you hit the corner point. However at lower lattitudes (eg. LHR BGI) there could be a few initial autothrottle intercepts before things settled down. This whole incredible routine completely took care of the insurmountable problem, a problem that was shown not only to be insurmountable, but was put to bed forever, by people like ChristiaanJ.
I hope that my explanation here does not sound too much like gibberish.
EXWOK
I think you've guessed right as far as my identity goes; it's great that it's not just Concorde pilots I can bore the socks off now
PS. I bet the ex-SEOs LOVED your comments
Dude
aaah yes, Max Climb/Max Cruise modes. I'd not forgotten this my friend, I was going to say a few words about that in a future post, but maybe we can do that now. (And I'd love to hear more of your comments on this here too, ChristiaanJ). The intake and autopilot modifications were in a way complimentary it's true, but really dealt with separate problems, at least in my view:
The intake control unit software change (a change to the control law that limited engine N1 as a function of intake local Mach number, Mo, and inlet total temperature, T1) was able to put an absolute limit on aircraft achievable Mach number during Mmo overshoots, but it would not PREVENT Mmo overshoots occurring altogether, it was more of a safety brake. This particular overspeed problem manifested itself well before route proving, and in fact the intake system 'fix' resulted in the Thrust Auto Reduce System being deleted, electronic control boxes and all. The TAR system was fitted on all development aircraft equiped with the digital intake system, and it tried (in vain) to limit extreme Mach overshoots. The production aircraft retained the TAR wiring and locked out circuit breakers, as well as two vacant spaces on the electronic racks. The prime reason for all these efforts were that some of the rapid excessive Mach overshoots quite often drove the intake into surge; the modification to this N1 limiter control enabled engine mass flow to be controlled in such a way that these surges could be prevented during temperature shears. The aircraft Mach limit was an extremely useful fringe benefit.
The AFCS mode change from what was Max Op and Max Op Soft (always loved that name) to Max Climb/Max Cruise was at a stroke able to deal with the regular Mmo overspeeds that kept on occuring during, as you say, the route proving trials of 1975, when British aircraft G-BOAC and the French aircrfraft F-BTSD carried out pre entry into service evaluation flights, SD sadly was the aircraft that was tragically lost at Gonez in July 2000). The Max Climb/Max Cruise AFCS mode combo is a mode like no other that I've personally seen before or since anywhere, (it for instance resulted an elsewhere taboo; an autopilot and an autothrotte working together IN A SPEED MODE).
This problem encountered primarily at lower lattitudes, (for example, G-BOAC doing route proving flights out of Singapore), occurring initially as the aircraft reached Mach 2. It was termed 'the insurmountable problem', but the AFCS designers (such as ChristiaanJ) fortunately did not have 'insurmountable problems' in their vocabulary. The issue was that the aircraft would have been climbing rapidly at Vmo of 530 KTS, with throttles at the gate as usual, At exactly 50,189' we hit what was known as 'the corner point' in the flight envelope, where 530 KTS IAS equated to Mach 2 exactly. Max Op mode would then 'let go' of the Vmo segment, and try and control the aircraft to Mach 2. (As the aircraft climbed, Vmo itself would progreesively decrease in order to equate to Mmo, or 2.04 Mach). But in very cold conditions, the aircraft still 'wanting' to accelerate, and the simple Max Op/Max Op Soft modes just could not cope with gentle pitch changes alone. The problem became even bigger during the cruise/climb when severe temperature shears occured, and routinely regular Mmo exceedences occured. Something had to be done, and something WAS done and how; enter Max Climb/Max Cruise. It was really a classic piece of design, where the aircraft would do the initial supersonic climb in Max Climb mode. This mode itself was relatively simple, in that it was more or less a Vmo -Vc hold mode. That meant that the difference at selection between indicated airspeed, Vc and Vmo would be maintained, with a vernier datum adjust to this being available. In practice this mode was selected pretty much at Vmo, so datum adjusting was not always required. Now comes the clever part; the autothrottle, this would operate in standy mode at this point, just waiting there doing nothing, with the throttles at maximum as before. So the aircraft would now climb as Vmo increased to 530 KTS, and then following a now constant Vmo of 530 KTS until the magic 'corner point' (51, 189' remember). Now all hell would break loose; the mode would automatically change to Max Cruise, the autothrottle would also be automaically selected to Mach Hold mode (initially datumed here to Mach 2) and the throttles would retard, attempting to hold this Mach 2 datum, and the autopilot is commands a 'fly up' signal, over a 20 second lag period to 600'/minute. Now comes an even cleverer (?) part; the autothrottle Mach Hold datum is gradually increased over a 100 second period towards Mach 2.02, and so in stable conditions the throttles would now gradually increase again until they once more reach the maximum limit. At this point, the autothrottles now come out of Mach Hold mode and back into the waiting in the wings standby mode. The autopilot would now cancel it's 600' fly up, demand, returning to a datum of Mach 2. There was a little more complexity built in also, where the difference between the 'commanded' and actual vertical speeds offset the autoplilot Mach 2 datum. This would apply whether the autothrottle had cut in (+600'/min demand) or with the throttles back at maximum (0'/minute demand. A positive climb error tweaked the cruise Mach up slightly, a negative error (eg. in a turn) the converse was true. The effect of all of this complexity was that the aircraft itself could 'scan' until it settled at a point where the throttles could be at maximum, and the speed between Mach 2 and 2.02. On the North Atlantic, with warmer ISA temperatures, there was usually just the initial routine with the autothrottle as you hit the corner point. However at lower lattitudes (eg. LHR BGI) there could be a few initial autothrottle intercepts before things settled down. This whole incredible routine completely took care of the insurmountable problem, a problem that was shown not only to be insurmountable, but was put to bed forever, by people like ChristiaanJ.
I hope that my explanation here does not sound too much like gibberish.
EXWOK
I think you've guessed right as far as my identity goes; it's great that it's not just Concorde pilots I can bore the socks off now
PS. I bet the ex-SEOs LOVED your comments
Dude
Last edited by M2dude; 25th Aug 2010 at 01:14 . Reason: missed out some info' (sorry)
24th Aug 2010, 23:33
permalink Post: 103
Landroger
Wow, that's a very interesting question, do you mind if I give it a tiny slant of my own, namely system distribution?
Concorde had an ENORMOUS number of electronic control boxes, for example the powerplant alone used TWENTY SIX rather heavy computers and control units, all of which used conventional 1970's manufacturing technology. (Although the intake box was a work of art; rows and rows of double sided PCBs completely crammed with TTL chips). This whole entourage literally weighed a ton, and could be easily replaced by four modern relatively light units with multiple redundancy built in). Even the AFCS used a total of sixteen heavy boxes, again these could be reduced to three, for a modern triple channel system. The three INUs and two ADCs (Very heavy units all) could be replaced with a single ADIRU and SAARU. To complete the package two FMCs (which would also furnish autothrottle functions) could be added. A massive weight saving could be made on the FBW system, by removing the bulky mechanical components (the feel and relay jacks as well as all the mechanical control runs and the massive mixing unit under the rear floor). Careful design could easily provide a full authority triplex or quadraplex FBW system. The current controls could be replaced with either an Airbus or Boeing type system, using either a sidestick (Airbus) or retain a conventional control column system (B777/787) using electric backdrive. The pilots can decide this one. A modern databus system would also be required for providing communication and redundancy; ARINC 629 would be MY preferred choice). The wholesale replacement of the various control units and computers, not to forget miles of wiring, as well as some bulky mechanical hardware would in my view save around 3 tonnes or more in weight alone. A now far more accurate control of aircraft systems would also bring major efficiency savings. As far as saving space, that possibly free up a couple of seat rows, if it were all done properly.
We can all dream I suppose
Dude
Quote:
| My question, which is a bit of a tilt at windmills, is this; If you had to build Concorde all over again with the same airframe and engines, how much more room, how much lighter and how much more capable would the electronics be if they were made using the latest surface mount, Extremely High Density integrated circuits and microprocessors? |
Concorde had an ENORMOUS number of electronic control boxes, for example the powerplant alone used TWENTY SIX rather heavy computers and control units, all of which used conventional 1970's manufacturing technology. (Although the intake box was a work of art; rows and rows of double sided PCBs completely crammed with TTL chips). This whole entourage literally weighed a ton, and could be easily replaced by four modern relatively light units with multiple redundancy built in). Even the AFCS used a total of sixteen heavy boxes, again these could be reduced to three, for a modern triple channel system. The three INUs and two ADCs (Very heavy units all) could be replaced with a single ADIRU and SAARU. To complete the package two FMCs (which would also furnish autothrottle functions) could be added. A massive weight saving could be made on the FBW system, by removing the bulky mechanical components (the feel and relay jacks as well as all the mechanical control runs and the massive mixing unit under the rear floor). Careful design could easily provide a full authority triplex or quadraplex FBW system. The current controls could be replaced with either an Airbus or Boeing type system, using either a sidestick (Airbus) or retain a conventional control column system (B777/787) using electric backdrive. The pilots can decide this one. A modern databus system would also be required for providing communication and redundancy; ARINC 629 would be MY preferred choice). The wholesale replacement of the various control units and computers, not to forget miles of wiring, as well as some bulky mechanical hardware would in my view save around 3 tonnes or more in weight alone. A now far more accurate control of aircraft systems would also bring major efficiency savings. As far as saving space, that possibly free up a couple of seat rows, if it were all done properly.
We can all dream I suppose
Dude
24th Aug 2010, 23:38
permalink Post: 104
M2dude
...The Max Climb/Max Cruise AFCS mode combo is a mode like no other that I've personally seen before or since anywhere...
True.
On descent, with the throttles at idle, it also worked beautifully as a MAX DESC mode
It was a very versatile mode.
Best Regards
Bellerophon
...The Max Climb/Max Cruise AFCS mode combo is a mode like no other that I've personally seen before or since anywhere...
True.
On descent, with the throttles at idle, it also worked beautifully as a MAX DESC mode
It was a very versatile mode.
Best Regards
Bellerophon
25th Aug 2010, 15:30
permalink Post: 112
M2dude
et al,
I have the rare privilege of actually having one of those rare "secret" air intake computers (AICU) sitting right next to my desk.
The circuit boards are mostly quite neat, with only the odd wire strap here and there.
However, the wiring of the unit itself, between the connectors, is a nightmare.
This is one of the PROM boards from the AICU, with one of the PROMs taken out of its socket. I have more photos, but will have to download those first, if anyone is interested.
Landroger
They're operational amplifiers, one per can!
Don't forget that all the computing in the AFCS computers was analog, not digital!
The vast majority were LM101As, with 741s in non-critical locations, and the odd LM108 for the really hiigh-precision stuff.
The board is actually a true antique, dating from one of the development aircraft.
We did not always do the kind of "butcher job" I described for the A/T. If there was enough time between major mods, the "firm" would redesign the board(s) and send us a new set, and the old ones would be binned... it made for better reliability. I kept a few as souvenirs.
I see you missed the real connector!
It's the big blue "thing" at the centre of the board, with no less than 80 pins.
This is the back of the card
This is the central connector closer up
The idea wasn't bad at first sight.... it allowed stacking three boards on top of each other, so that many signals could pass from one board to another without any intermediate wiring. A small motherboard with a fourth conector would then take certain signals to other stacks, etc.
Another claimed advantage was that it made the board layout easier.
What was learned only gradually was that those connectors were hideously difficult to solder in place, and even more difficult to repair. Concorde was too far "on the way" to redesign the entire AFCS, so we learned to live with them, but the concept was abandoned afterwards.
The central connectors were only used for the analog boards ; the logic boards used more conventional 84-pin connectors on one side.
This is one of the logic boards.
Re the weight question, I would say M2dude 's answer is a lot better than mine, so ignore my remarks.....
Re the wiring, Concorde had about 300km of it.
IIRC the A380 Flying Hippo, which is vastly bigger, "only" has about 500km of wiring, and it seems a lot of that is the IFE (in-flight entertainment)
CJ
I have the rare privilege of actually having one of those rare "secret" air intake computers (AICU) sitting right next to my desk.
The circuit boards are mostly quite neat, with only the odd wire strap here and there.
However, the wiring of the unit itself, between the connectors, is a nightmare.
This is one of the PROM boards from the AICU, with one of the PROMs taken out of its socket. I have more photos, but will have to download those first, if anyone is interested.
Landroger
Quote:
| What little horrors hid inside those TO5 cans? |
Don't forget that all the computing in the AFCS computers was analog, not digital!
The vast majority were LM101As, with 741s in non-critical locations, and the odd LM108 for the really hiigh-precision stuff.
Quote:
| Apart from the fact that your board must be brand new - the track cutters and wire linkers hadn't got at it yet! |
We did not always do the kind of "butcher job" I described for the A/T. If there was enough time between major mods, the "firm" would redesign the board(s) and send us a new set, and the old ones would be binned... it made for better reliability. I kept a few as souvenirs.
Quote:
| What is interesting are the connections - only eight pins, as far as I can tell? We had 15/25/60 pin 'D' connectors or multi path, gold 'edge' connectors at least |
It's the big blue "thing" at the centre of the board, with no less than 80 pins.
This is the back of the card
This is the central connector closer up
The idea wasn't bad at first sight.... it allowed stacking three boards on top of each other, so that many signals could pass from one board to another without any intermediate wiring. A small motherboard with a fourth conector would then take certain signals to other stacks, etc.
Another claimed advantage was that it made the board layout easier.
What was learned only gradually was that those connectors were hideously difficult to solder in place, and even more difficult to repair. Concorde was too far "on the way" to redesign the entire AFCS, so we learned to live with them, but the concept was abandoned afterwards.
The central connectors were only used for the analog boards ; the logic boards used more conventional 84-pin connectors on one side.
This is one of the logic boards.
Re the weight question, I would say M2dude 's answer is a lot better than mine, so ignore my remarks.....
Re the wiring, Concorde had about 300km of it.
IIRC the A380 Flying Hippo, which is vastly bigger, "only" has about 500km of wiring, and it seems a lot of that is the IFE (in-flight entertainment)
CJ
25th Aug 2010, 22:17
permalink Post: 122
Quote:
|
Originally Posted by
DozyWannabe
Any magnetic core memory in any of those systems?
|
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
25th Aug 2010, 23:04
permalink Post: 123
Quote:
|
Originally Posted by
Landroger
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.
|
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.
Quote:
| I just noticed DozyWannabe's question about core memory. I guess it would have been core... |
CJ
26th Aug 2010, 00:07
permalink Post: 124
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
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
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
Quote:
| 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; 26th Aug 2010 at 00:20 .
26th Aug 2010, 14:27
permalink Post: 131
Quote:
|
Originally Posted by
M2dude
As far as AFCS goes, can you check your records?
|
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 14:52 . Reason: typo
3rd Sep 2010, 19:58
permalink Post: 202
ChristiaanJ
During AUTOLAND a flare manoeuvre was instigated by the Pitch Computer at 50' radio, where a fairly simple flare law was invoked. I seem to remember that the law , which used a combination of radio rate (from the RadAlt) and vertical acceleration (from the INS) gave you a commanded height rate of 10'/second at 50', exponentially reducing to 1.7'/second at point of main wheel touch down.
The autoland on Concorde was both extremely accurate and reliable, and an awful lot of guys said they hated using it 'because it can land the aircraft
better than I can'; their words NOT mine. (Personally I never bought that one, the guys were just modest as far as I was concerned
). This in my opinion is an absolute testament to the AFCS designers; ChristiaanJ and his colleagues at SFENA and GEC Marconi.
To give the complete final approach story; as the aircraft tracked the glideslope in LAND mode, the autopilot G/S deviation, like most aircraft, was geared as an inverse function of radio altitude, and at 75' radio this deviation was flushed down the loo altogether, leaving the A/P to hold radio rate for just a few feet. At 50' the flare was instigated, and at around 35' DECRAB was commanded, where the yaw channel would use a rudder input alone to 'kick off drift' and align the aircraft with the runway centreline. (Concorde did not employ a fwd slip manoeuvre in crosswind conditions, being a slender delta). The 'final' command was at 15' radio, when the autothrottle smartly retarded the throttles. (The Pitch Computer flare law of course continuing to control decent rate all the way down). On touchdown the autopilot would be manually disengaged and the nose gently (usually
) lowered to the ground. (Concorde was only designed and certified as a CAT 3A system, so there was no automatic rollout guidance. However there was a runway guidance symbol on the ADI, which used a combination of Localiser deviation and lateral acceleration, to give you runway rollout track).
Now the flare law was tested every autoland, at G/S capture, and failure of this test resulted in the loss of LAND 3 status on the landing display panel. The most common defect of all with the Concorde autoland was in fact failure of the flare test, when at G/S capture, the previously illuminated LAND 3 indication would drop all of it's own to LAND 2. A simple changeover of autopilot paddle switches would nail the offending Pitch Computer, which would then be replaced before the next trip.
Dude
Quote:
| During landing, Concorde isn't flared at all, it is flown onto the ground at a constant pitch attitude. |
The autoland on Concorde was both extremely accurate and reliable, and an awful lot of guys said they hated using it 'because it can land the aircraft
better than I can'; their words NOT mine. (Personally I never bought that one, the guys were just modest as far as I was concerned
). This in my opinion is an absolute testament to the AFCS designers; ChristiaanJ and his colleagues at SFENA and GEC Marconi.
To give the complete final approach story; as the aircraft tracked the glideslope in LAND mode, the autopilot G/S deviation, like most aircraft, was geared as an inverse function of radio altitude, and at 75' radio this deviation was flushed down the loo altogether, leaving the A/P to hold radio rate for just a few feet. At 50' the flare was instigated, and at around 35' DECRAB was commanded, where the yaw channel would use a rudder input alone to 'kick off drift' and align the aircraft with the runway centreline. (Concorde did not employ a fwd slip manoeuvre in crosswind conditions, being a slender delta). The 'final' command was at 15' radio, when the autothrottle smartly retarded the throttles. (The Pitch Computer flare law of course continuing to control decent rate all the way down). On touchdown the autopilot would be manually disengaged and the nose gently (usually
) lowered to the ground. (Concorde was only designed and certified as a CAT 3A system, so there was no automatic rollout guidance. However there was a runway guidance symbol on the ADI, which used a combination of Localiser deviation and lateral acceleration, to give you runway rollout track).
Now the flare law was tested every autoland, at G/S capture, and failure of this test resulted in the loss of LAND 3 status on the landing display panel. The most common defect of all with the Concorde autoland was in fact failure of the flare test, when at G/S capture, the previously illuminated LAND 3 indication would drop all of it's own to LAND 2. A simple changeover of autopilot paddle switches would nail the offending Pitch Computer, which would then be replaced before the next trip.
Dude
3rd Sep 2010, 21:58
permalink Post: 208
Quote:
|
Originally Posted by
Brit312
If I remember correctly ground effect tended to force the aircraft nose down, so requiring the pilots to pull back on the stick as if they were flaring ,but in fact what they were doing was as you say maintaining the pitch attitude constant.
|
M2dude ,
Reading your description of the autoland, you must be quoting from documentation, no?
I've still got the AFM, but i don't think it's as detailed as that?
And for me it's now too long ago to remember it in full detail, without any documentation to cross-check.
Quote:
| This in my opinion is an absolute testament to the AFCS designers; ChristiaanJ and his colleagues at SFENA and GEC Marconi. |
BTW, it was still Elliott at the time.... both SFENA and Elliott have gone through a few permutations since.
CJ
6th Sep 2010, 09:17
permalink Post: 222
Coffin Corner
Nick Thomas
Just like Christiaanj I'm trying to dig up an accurate flight envelope diagram. (A lot of my Concorde 'technical library' is out on long term loan), but I would suggest that anywhere within Concorde's published flight envelope you never hit any equivilant to Coffin Corner, a la' U2. The whole issue is really one of air DENSITY, rather that pressure, where as you climb at a given Mach Number, your Indicated airspeed (IAS) falls away with altitude. (Velocity of sound being primarily tied to static air temperature). Now if you are climbing in the stratosphere, where temperature is more or less constant up to around 65,000', you can say that your TRUE Airspeed (TAS) is also constant with climb at a given Mach number. But lift and drag are functions of IAS (the equivalent airspeed that the aircraft would 'feel' at sea level) and not TAS. Because the U2 had a very low Maximum allowable Mach number (Mmo) as IAS fell away with altitude, it would get to the point where it's lowest permitted airspeed (we called this VLA) got to within a few knots of Mmo and severe aerodynamic buffering. i.e. you were screwed with nowhere to go but down
.
In the case of Concorde, Mach 2 at FL500 was 530KTS, falling to 430KTS at FL600. Although we have less lift due to 100KTS lower IAS, the aircraft is now much lighter (this is the whole principal of cruise/climb) which keeps the universe in balance, but drag is now significantly lower too, getting us better MPG
.
On the ASI, the only limitation displayed was Vmo; however the Machmeter did display fwd and aft CG limits at a given Mach number. The ONLY time that Concorde would experience relatively low speeds at altitude was at Top of Descent. I'm a little fuzzy here how it all worked exactly (it's an age thing you know), I'm sure one of the pilots can correct me, but I seem to remember that the autothrottle was disconnected, ALTITUDE HOLD was selected on the AFCS, and the throttles slowly retarded. (If you pulled back too far you'd often get a gentle 'pop surge' from the engines, and you had also to be wary of equipment cooling airflow too). The aircraft was then allowed to gently decelerate, still at TOD altitude, until Mach 1.6, when power was tweaked to give 350KTS IAS and IAS HOLD was selected. The aircraft was now free to carry out her loooong descent to 'normal' altitudes. VLA on Concorde was not directly displayed as you never flew anywhere near it, and also every pilot knew his VLA
. (Stray into this and you'd get a 'stick' shaker warning.
I hope this blurb helps Nick
Dude
Just like Christiaanj I'm trying to dig up an accurate flight envelope diagram. (A lot of my Concorde 'technical library' is out on long term loan), but I would suggest that anywhere within Concorde's published flight envelope you never hit any equivilant to Coffin Corner, a la' U2. The whole issue is really one of air DENSITY, rather that pressure, where as you climb at a given Mach Number, your Indicated airspeed (IAS) falls away with altitude. (Velocity of sound being primarily tied to static air temperature). Now if you are climbing in the stratosphere, where temperature is more or less constant up to around 65,000', you can say that your TRUE Airspeed (TAS) is also constant with climb at a given Mach number. But lift and drag are functions of IAS (the equivalent airspeed that the aircraft would 'feel' at sea level) and not TAS. Because the U2 had a very low Maximum allowable Mach number (Mmo) as IAS fell away with altitude, it would get to the point where it's lowest permitted airspeed (we called this VLA) got to within a few knots of Mmo and severe aerodynamic buffering. i.e. you were screwed with nowhere to go but down
.
In the case of Concorde, Mach 2 at FL500 was 530KTS, falling to 430KTS at FL600. Although we have less lift due to 100KTS lower IAS, the aircraft is now much lighter (this is the whole principal of cruise/climb) which keeps the universe in balance, but drag is now significantly lower too, getting us better MPG
.
On the ASI, the only limitation displayed was Vmo; however the Machmeter did display fwd and aft CG limits at a given Mach number. The ONLY time that Concorde would experience relatively low speeds at altitude was at Top of Descent. I'm a little fuzzy here how it all worked exactly (it's an age thing you know), I'm sure one of the pilots can correct me, but I seem to remember that the autothrottle was disconnected, ALTITUDE HOLD was selected on the AFCS, and the throttles slowly retarded. (If you pulled back too far you'd often get a gentle 'pop surge' from the engines, and you had also to be wary of equipment cooling airflow too). The aircraft was then allowed to gently decelerate, still at TOD altitude, until Mach 1.6, when power was tweaked to give 350KTS IAS and IAS HOLD was selected. The aircraft was now free to carry out her loooong descent to 'normal' altitudes. VLA on Concorde was not directly displayed as you never flew anywhere near it, and also every pilot knew his VLA
. (Stray into this and you'd get a 'stick' shaker warning.
I hope this blurb helps Nick
Dude
7th Sep 2010, 15:34
permalink Post: 261
Brit312
---- that reminds me....
On the two prototypes, the AFCS controller was located on the centre pedestal, and had two big rotary multiposition switches to select the autopilot/flight director modes, plus the autopilot, flight director and autothrottle engage switches.
On the preproduction and production aircraft, the design was totally changed and became the big box with rows of pushbuttons and little handwheels, to set things like altitude and speed, that one now sees at the top centre of the instrument panel, just under the windscreen and above the engine instruments.
It was not until years and years later that I had an occasion to visit a VC-10 cockpit .... to discover how similar the VC-10 AFCS controller was to the prototype Concorde one.
No wonder... both were made by Elliott.
CJ
On the two prototypes, the AFCS controller was located on the centre pedestal, and had two big rotary multiposition switches to select the autopilot/flight director modes, plus the autopilot, flight director and autothrottle engage switches.
On the preproduction and production aircraft, the design was totally changed and became the big box with rows of pushbuttons and little handwheels, to set things like altitude and speed, that one now sees at the top centre of the instrument panel, just under the windscreen and above the engine instruments.
It was not until years and years later that I had an occasion to visit a VC-10 cockpit .... to discover how similar the VC-10 AFCS controller was to the prototype Concorde one.
No wonder... both were made by Elliott.
CJ
12th Sep 2010, 12:05
permalink Post: 329
Hi Steve, good question. You could not prime Alt ACQ directly from MAX CLIMB/MAX CRUISE, but I'm sure the guys would confirm that FL600 was nonetheless set in the AFCS altitude window. If you did come close to FL600, then you would get an altitude alert audio and visual warning anyway, but the crew would obviously know anyway. The guys will have to confirm this but I think that ALT HOLD would be selected at this point, and the autopilot would now constrain the altitude by varying pitch attitude. You would normally be flying in nice cold conditions for this to occur, hardly ever on the North Atlantic, but on the LHR-BGI sector it would occur as often as not. (As usual, apologies to my all flying pals if I'm talking rubbish again
).
Dude
).
Dude