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It is easy [by looking in my book] to confirm the starting sequence was
3421 or for a Push Back it was 3 then 2 followed by 4 then 1, after pushback was complete Now the hard part is to remember why, and perhaps it was because that is the way in BOAC/BA we had always started engines, but on previous aircraft I do remember there being a reason such as brake pressure or electrics, which was not the case on Concorde. However I seem to remember that the hydraulic pump layout on pre production Concordes was not always the same as the airline version, so this might have had some influence However by starting 3 then 4 first it did allow engine start to commence with the passenger finger still in place. Now unlike the French the flying control checks were carried out by a pilot as engines were being started and it started with "Blue" being selected which was sourced from 3 and 4 engines. Now I think this was only because 3 and 4 were the first engines to be started rather than the reason, but it was handy to speed things up. Now I have heard a rumour you understand that sometimes when things were running late the 3 and 2 engines would be started at the same time, but you have to understand this is only a rumour:ooh: |
Unlikely Information
Hi, Just caught this question on a search, a bit more info.
My Father was Project Manager for the testing of the engines. I remember spending a few weekends with him driving around to look at suitable railway tunnels. I didn't remember where it was but your post identified it. Once the test-bed was set up dead birds were collected to be fired in to the engine. As stated it was to prove a disk destruction would be contained within the housing: it was. There were problems with some break-ins, the company put up various hazard signs to scare away local youths (presumed responsible), it worked but then they had to take them down a reassure the local council there were no such hazards. My Father was also responsible for the flying test bed, placing an Olympus in the bomb bay of a Vulcan bomber. Hope this helps. |
Seats
Guys - not really a technical question but probably of interest.
Like ShaggySheepDriver I'm one of the guides on Alpha Charlie at Manchester. As part of the tour we always say where the Queen sat. But people always have questions about others. e.g. - David Frost was always towards the back but was he actually at the back in R26 ? Question is :- Are there any interesting people with quirky stories who sat elsewhere ? (As per that John Cleese story a few pages back). |
e.g. - David Frost was always towards the back but was he actually at the back in R26 ? |
Hi all,
Sorry for bump this tread but I'm just wonder why Tank 8 is bigger than Tank 6 which is sit left to the tank 8. Is there any specific reason for this? Thanks for all of yours reply Best regards |
I'm just wonder why Tank 8 is bigger than Tank 6 which is sit left to the tank 8. Is there any specific reason for this? |
M2 dude
Firstly thanks for a very interesting thread. Regarding post 88 (I know it was last year) and the hydraulic systems, the use of M2V would also be required as the pipes were Titanium and Skydrol (ester) based fluids will cause hydrogen embrittlement in Titanium and cracking. For me I had a couple of years working on the aircraft at BA in the late 70's and was always reminded that the design was in the best British military design tradition and training as a gynacologist would have been handy when replacing any component! Good times. |
I'm so glad and flattered at your comments, thank you very much spannersatKL. You are so right about working on the lady. It often seemed like gynacology, or even 'brain surgery 'for fun and profit' a lot of the time when changing stuff on 'The Rocket'.
M2V really was great stuff though, although now it is as rare as rocking horse excrement. (Got any spare)??? Best Regards Dude :O |
Dude/SpannersatKL
It often seemed like gynacology, or even 'brain surgery 'for fun and profit' a lot of the time when changing stuff on The Rocket'. Roger |
Originally Posted by spannersatKL
(Post 6344797)
....the use of M2V would also be required as the pipes were Titanium and Skydrol (ester) based fluids will cause hydrogen embrittlement in Titanium and cracking.
...I was always reminded that the design was in the best British military design tradition My own field was the AFCS, and one of my experiences was discovering, (quite recently) that the prototype Concorde AFCS controller had obvious family relations with the one on the VC-10 (so not military). Logical, both were designed by Elliott. .... and training as a gynacologist would have been handy when replacing any component! Good times.
Originally Posted by M2dude
M2V really was great stuff though, although now it is as rare as rocking horse excrement. (Got any spare)???
Concorde always leaked as a sieve... (escept at Mach 2) and still does to this day. We collect the M2V in the drip pans, filter it, and re-use it, but a few uncontaminated drums or boxes would be very gratefully received.... never mind the "Best By" date. CJ |
Bellerophon
You call 3-2-1 Now, start your stopwatch, pre-set to countdown from 58 seconds, and slam the throttles fully forward till they hit the stops. Four RR Olympus engines start to spool up to full power and four reheats kick in, together producing 156,000 lbs of thrust, but at a total fuel flow of 27,000 US gallons per hour. A touch of left rudder initially to keep straight, as the #4 engine limiter is limiting the engine to 88% until 60 kts when it will release it to full power. The F/O calls Airspeed building, 100 kts, V1, and then, at 195 kts, Rotate. You smoothly rotate the aircraft, lift-off occurs at around 10° and 215 kts. You hear a call of V2 but you keep rotating to 13.5° and then hold that attitude, letting the aircraft accelerate. The F/O calls Positive Climb and you call for the Gear Up. On passing 20 feet radio height, and having checked the aircraft attitude, airspeed and rate of climb are all satisfactory, the F/O calls Turn and you slowly and smoothly roll on 25° left bank to commence the turn out over Jamaica bay. Some knowledgeable passengers will have requested window seats on the left side of the aircraft at check-in, and are now being rewarded with a very close look at the waters of Jamaica Bay going by very fast! As you accelerate through 240 kts, the F/O calls 240 and you pitch up to 19° to maintain 250 kts and keep the left turn going to pass East of CRI. |
How many shockwaves does the concorde's inlet produce? I've been told it was like 3 or so, but looking at some diagrams it looks like there are 7... two stronger ones, three weaker ones, a bendy stronger one, a gap and then the terminal shock.
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Regarding the engine start-up, was Two-Engine Taxi out ever considered/used in an effort to save some of the vast amound of fuel consumed before take-off.
Related I guess to the above, was there a minimum time limit after engine start before which full thrust could be applied? |
1. Yes ( of course if you have more then 2 )
2. Yes ( every engine, even the one in car or a motorbike etc. ) |
Jane-DoH
How many shockwaves does the concorde's inlet produce? I've been told it was like 3 or so, but looking at some diagrams it looks like there are 7... two stronger ones, three weaker ones, a bendy stronger one, a gap and then the terminal shock. 1) The first shock was generated from the top lip of the intake 2) A second shock is generated from the fwd ramp hinge 3) A third isentropic fan shock is generated from the progressively curved section of the fwd ramp 4) A 4th shock was generated fron the bottom lip 5) A terminal shock system is generated by the coalescence of still supersonic and now subsonic air at the upper section of the ramp area. http://i1237.photobucket.com/albums/...corde/Shox.jpg Hopefully these two diagrams will help. The first hand illustration above gives the 'theoretical' shock pattern and the second below gives an illustration of practical flows within the inlet. Both assume critical operation at Mach 2. http://i1237.photobucket.com/albums/...ockComplex.jpg I hope all this blurb helps Best regards Dude :O |
During the take off roll there was a power check called (by the FE, I think). I've heard this on recordings and videos variously as "power checked" and "Power set". Assuming they are one and the same check, which is correct?
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Dude, those are very nice illustrations, but I would make a small correction to the lower picture - the bleed flow is shown as entering the void at the front of the slot between the front and rear ramps whereas in reality it goes (sorry went :-( ) in at the rear behind the terminal shock. The increase in pressure behind that shock was the 'drive' for bleed flow.
Regards CliveL |
During the take off roll there was a power check called (by the FE, I think). I've heard this on recordings and videos variously as "power checked" and "Power set". Assuming they are one and the same check, which is correct I think you are referring to the 100kt call, when the F/E was expected to give a call as to the state of the powerplant [both engine and reheat] achieving desired power for take off. He was assisted in this decision by the illumination of 4 green lights [ one per engine] which came on if the engine power was OK. Should one green light fail then he would confirm the correct engine operation by observing that engine's N2 and Area position If all OK at 100kts the F/E would call ---- "Power Set" If not all Ok then he would call ----------" Engine Failure" which would result in a rejected Take off In the early days there was no concession and every take off had to have 4 green lights illuminated so the call then was " 4 Greens" , but when the concession came along that term would not fit so the change in call The concession were 1] one green light out [seeabove] 2] and basically if weight, and airport conditions allowed it a take off could be continued even with one reheat failed at 100kts Up to 60 kts the F/E could reselectt a failed reheat so hoping it would be OK by 100kts At 100kts the conditions in the above concessions applied Above 100kts the take off would continue even if a reheat failed however if another fails when below V1 the take off would be rejected So finally to answer your question the correct call [well in 1998] was " Power Set " |
:OCliveL
Dude, those are very nice illustrations, but I would make a small correction to the lower picture - the bleed flow is shown as entering the void at the front of the slot between the front and rear ramps whereas in reality it goes (sorry went :-( ) in at the rear behind the terminal shock. The increase in pressure behind that shock was the 'drive' for bleed flow. (As always you are of course 100% on the bal. And what do aerodynamisits know about aerodynamics anyway :) :D :)). Best regards Dude :O |
And what do aerodynamisits know about aerodynamics anyway CliveL |
Thanks Brit 312. "Power set" it is, then. I was aware of the '3 reheat' possibility which is decided before T/O depending on T/O parameters ('is this a 3 re-heat day or a 4 re-heat day?').
On the P1 side of the cockpit is a small hinged piece of metal which can be moved to show '3' or '4'. This is set before flight depending on whether 3 or 4 re-heats are the acceptable minimum for take off that day, so if there is a re-heat failure on T/O, a glance at that indicator will show if it's OK to continue with '3 lit' or not. |
Ahhhh... the famous Reheat Capability Indicator. (Yes that was its official title). I seem to remember that before we did the modification to fit the 'RCI' in the late 1970s, the guys used to set an INS CDU thumbwheel as a memo to whether the take-off was a 'go-er' or a 'stopper'.
It seems a million years ago when we fitted this high presicion lump of alluminium. (Hang on a minute, it WAS :p). Best regards Dude :O |
I've read the entirety of this thread with great interest, having never got to see Concorde in flight, but only visited OAG in Seattle. What a beautiful machine!
My question is: disregarding the certified FL600 / M2.04 / 127ºC restrictions, how high and/or fast do you Concorde builders and designers think she could have gone? :) |
Hello skyhawkmatthew!
M2dude gave a good answer on your question in post #1085, so I think I may quote this here again.
Originally Posted by M2dude
As far as the MAX SPEED bit goes, Concorde was as we know flown to a maximum of Mach 2.23 on A/C 101, but with the production intake and 'final' AICU N1 limiter law, the maximum achievable Mach number in level flight is about Mach 2.13. (Also theoretically, somewhere between Mach 2.2 and 2.3, the front few intake shocks would be 'pushed' back beyond the lower lip, the resulting flow distortion causing multiple severe and surges).
The maximum altitude EVER achieved in testing was I believe by aircraft 102 which achieved 68,000'. |
M2Dude
3) A third isentropic fan shock is generated from the progressively curved section of the fwd ramp 5) A terminal shock system is generated by the coalescence of still supersonic and now subsonic air at the upper section of the ramp area. |
What's an isentropic fan-shock? So the lower lip forms a normal shock and the airflow goes subsonic immediately behind it, the supersonic flow above somehow collide and form a shock between the ramps? I understand how the subsonic and supersonic flow coming together would reduce the average velocity -- I'm still surprised the gap between the forward and rear ramps wouldn't act like a divergent surface and cause the supersonic flow to accelerate rather than come down to subsonic speed. |
CliveL
The first bit of the moveable front ramp was carefully shaped to give a sequence of weak shocks that reduced the Mach Number so gradually that shock losses were minimised. This was close to an isentropic process, hence the name. The whole point of the intake geometry was that the purely aerodynamic boundary between main duct and ramp void was infinitely flexible in shape, which made the design very tolerant of flow disturbances. |
Thanks for your reply CliveL and thanks M2Dude and CliveL again for the great
reply with detail about the intake.:D |
Must have been a highly efficient inlet for a Mach 2 plane: Two traditional oblique waves; a fan-shock (also oblique); a shockwave off the lip that is normal and oblique depending on how far you are away from the lip, and a normal terminal shock. So, isentropic would, in this context, mean that no shock-losses occurred at all? |
And a thank you from me CliveL for your superb explanations regarding intake shock structure. It can not be over-emphasised just what an amazing achievement the Concorde engine/intake combo was. I can think of no other design in the world, before or since, civil or military, where a supersonic engine/intake marriage gave such incredidable levels of performance, stability and predictability. I just regard myself as being extremely fortunate to have been able to 'play with' this amazing kit for so many years and see what design excellance really is. (And at least pertly understand it too).
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Power limit to 60kt
I believe that engine #4 was limited to somewhat less than max power until 60kt because of a vibration issue. Did this mean that reheat for that engine could not be selected until 60kt was achieved?
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All 4 reheats were selected 'on' before take off. They wouldn't actually light until the engine was up to a certain power, so the answer is 'no'. The power-limiting ensures no. 4's re-heat doesn't light below 60kts.
Watch a video of Concorde taking off which gives the view from behind. You'll notice no.4 light up marginally after the other 3 (but there's not much in it as it didn't take the aeroplane long to get to 60kts!). |
Not quite right: the reheats ignite if
(At temperatures colder than -35°C the engine control schedule limits the N1 of all engines to 88% or less.)
Originally Posted by Brit312
Up to 60 kts the F/E could reselect a failed reheat so hoping it would be OK by 100kts
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Thaks Quax. So all 4 reheats should light about the same time, then, regardless of power limiting on #4? It does seem that #4 lags a fraction in vids I've seen.
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This might be because the #4 engine accelerates less fast than the others due to the limiter, reaching 81% N1 a little bit later. But this thread is too brilliant for presumptions (don't want to repeat the mistake of my first post...;) ). Let's see what the Concorde-geniuses add.
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Unique design.
I can think of no other design in the world, before or since, civil or military, where a supersonic engine/intake marriage gave such incredidable levels of performance, stability and predictability. Without proper scheduling, disturbances inside the inlet could result in the shock wave being expelled forward--a phenomenon known as an "inlet unstart." That causes an instantaneous loss of engine thrust, explosive banging noises and violent yawing of the aircraft--like being in a train wreck. Unstarts were not uncommon at that time in the SR-71's development, Basically, a relatively small failure within the intake/spike structure of the SR71 engine, was enough to simply tear the airframe apart within seconds of onset. The scale of forces within these structures therefore, must be almost beyond imagination and yet the Concorde design was such that she did not suffer such destructive failures. My admiration for everyone who worked on her is endless. |
there were already several conduits through tank 11, such as hydraulics for the tail wheel, various electrics, and the 'backbone' fuel manifolds, that ended at the fuel jettison port in the tailcone.
A couple of fairly substantial air ducts would only have displaced a few hundred kgs of fuel at the most, out of the more than 10,000 kgs in tank 11. |
M2Dude
I can think of no other design in the world, before or since, civil or military, where a supersonic engine/intake marriage gave such incredidable levels of performance, stability and predictability. 911slf I believe that engine #4 was limited to somewhat less than max power until 60kt because of a vibration issue. |
Jane-DoH
One of the real beauties of the Concorde intake was that it was completely self-startiing, and so unstarts as such were never heard of. Regarding the vibrations thing, here is my post #80: The reason that #4 engine was limited to 88% N1 on take-off was an interesting one, down to something known as 'foldover effect'. This was discovered during pre-entry into service trials in 1975, when quite moderate levels of first stage LP compressor vibrations were experienced at take-off, but on #4 engine only. Investigations revealed that the vibrations were as the result of vorticies swirling into #4 intake, in an anti-clockwise direction, coming off the R/H wing leading edge. As the engine rotated clockwise (viewed from the front) these vorticies struck the blades edgewise, in the opposite DOR, thus setting up these vibrations. The vorticies were as a result of this 'foldover effect', where the drooping leading edge of the wing slightly shielded the streamtube flowing into the engine intake. #1 engine experienced identical vorticies, but this time, due to coming off of the L/H wing were in a clockwise direction, the same as the engine, so were of little consequence. It was found that by about 60 KTS the vorticies had diminished to the extent that the N1 limit could be automatically removed. Just reducing N1 on it's own was not really enough however; some of this distorted airflow also entered the air intake through the aux' inlet door (A free floating inward opening door that was set into the spill door at the floor of the intake. It was only aerodynamically operated). The only way of reducing this part of the problem was to mechanically limit the opening angle of the aux' inlet door, which left the intake slightly choked at take off power. (The aux' inlet door was purely aerodynamically operated, and diff' pressure completely it by Mach 0.93). |
Investigations revealed that the vibrations were as the result of vorticies swirling into #4 intake, in an anti-clockwise direction, coming off the R/H wing leading edge. |
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