Posts about: "Rolls Royce" [Posts: 63 Page: 2 of 4]¶

Oh darn it Feathers, if you insist (LOL).
First of all, what is rotating stall? All gas turbine engines are prone to this to some degree or another, the Olympus was particularly prone (so we discovered to our cost). What happens is that extremely LOW figures of N2, small cells of stalled air rotate around the anulus of the early stages of the HP compressor (at approximately half the rotational rpm), resulting in parts of the airflow becoming choked and highly distorted. This often results in the combustion process being disturbed to the extent that combustion instead of occuring in the combustion chamber, occurs in the turbine itself. This of course results in massive overheating of the turbine blades and stators (and is what is suspected occured in the #2 engine on G-BOAA in 1991.
To prevent running in rotating stall, the Olympus automatic fuel start schedule would accelerate the engine quickly to around 67% N2 before dropping back to the normal idle figure of around 65% N2. (The stall clearance N2 figure was ambient temperature dependant, the higher the temperature the higher the N2 that was required and hence scheduled by the automatics).
What had happened on G-BOAA was an engine starting/accelerating problem, where the N2 ran at a sub-idle of around 40% N2 for several minutes. This was enough for the malignant effects of rotating stall to take hold, and the resulting turbine blade failure over the Atlantic the following day. In all fairness to everyone involved, none of us, including Rolls Royce realised just how potentially serious this phenonomen was, and salutary lessons were learned by one and all. (The following year Air France had a similar failure; their first and last also).
I flew out to Shannon on a BAC 1-11, that was sent to fly the Concorde passengers back to London. As I and my colleague were coming down the ventral door steps of the 1-11, a chirpy Aer Lingus engineer asks 'have you guys come to fix the broken engine?, there are bits of it lying in the jet pipe'. Now up to now, from the information we'd been given in London, we thought that we were going to be looking at either an intake or engine induced surge, a few systems checks and boroscope inspections and we'd all be on our way, so we naturally thought the Aer Lingus guy was joking. He was most certainly was not; as you looked into the jetpipe (through the secondary nozzle buckets) you could see a large quantity of metal debris, accompanied by a strong smell of burnt oil. I remember this day well, it was the day that the first Gulf war ended; how ironic.
The aircraft departed on three engines, flown by a management crew late the following day, my colleague and I returned to London by Aer Lingus one day later. (No passengers whatsoever are permitted on ferry flights, even expendable ones like me).

Dude

Landroger
Good to see you here again Roger, I'll try my best to give you my take on rotating stall. (I worked very closely with Rolls Royce in the Concorde days, and everything I know about the process is thanks to them). Turbine engine combustion is a precise and delicate affair, particularly during start, and too much or too little fuel can cause severe problems. With rotating stall, the rotating cells of stalled air. if they manage to take 'hold' can cyclically choke the flow into the latter compressor stages (it's the cyclic nature of the cells that is the real problem, hence the 'rotating' stall term). The cells as they 'hit' the compressor blades (the cells are rotating at half shaft speed in the opposite direction of shaft rotation) can cause blade vibration and can also cause minor surges within the engine. The combustion fire literally can burn in the turbine section, but any distortion to the combustion process will result in local overheating, due to poor air/fuel mixing etc. In some engine types, damage can be also be caused to the HP compressor blades (due to vibration) but with the Olympus the main danger was to the turbine blades and stators. It's difficult to relate to any common analogy for this lot I'm afraid Roger.
Rotating stall was avoided in the Olympus by starting the engine with the primary nozzle driven wide open, and controlling two parameters; those being the opening rate of the fuel valve and the rate of rise of exhaust gas temperature. (During the start sequence, once ignition had occured the EGT rise was held to 6 degrees per second, right up until rotating stall clearance at 65% temperature corrected N2 ). So the engine accelerates without let or hinderance right through the danger zone, but was prevented from dipping below 65% temperature corrected N2, where the danger zone starts again. (Absolute minimal idle for the Olympus 593 was set at 61% N2).
I sincerely hope this blurb helps Roger, if not then feel free to ask again or PM me.
Regards

Dude

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

Dude

Nick Thomas
Oh the Rolls Royce EGT Trend Monitoring Programwas an incredible piece of kit indeed Nick. The idea was that you would input Mach, TAT, N1, N2 and EGT itself. The computer program written in BASIC (I still have a copy) would then calculate the 'brochure' EGT for those conditions (the brochure itself being based on a 127\xb0 ISA +5 day), and what the delta from this brochure figure actually was. This delta EGT trend over the last few flights was then plotted (it was the delta rather than the actual brochure itself that we were interested in) and if there was a sudden jump or dip from the previous flights, it was indicative of something wrong with the engine. A severe dip was indicative of compressor damage and a severe jump indicative of turbine damage. Boroscope inspections would be carried out in such a case, and the Trend Program was better than 90% accurate in terms of predicting engine problems, although these problems became less and less common as the engine design became more mature. (As a result of modifications embodied in the engine over the years). FOD damage ended up being the most common cause of headaches here.
The obvious remedy for confirmed compressor or turbine damage was to 'pull' the engine and replace it with a 'new' one; the damaged engine was then sent to Treforest in Pontypridd for overhaul. (These guys by the way did a really superb job ).

Best Regards
Dude

You and I both would love to see more of this video material, as you say it is totally priceless. I have no clue where most of it resides (if any is held by Airbus at Filton, then we are all screwed. It is possible I suppose that Rolls Royce might have some though; I'll have to check). But generally, I am afraid if I need any video material for lectures etc. my sources are invariably YouTube or my Great Uncle Google.

Regards
Dude

I found a reference (via Wikipedia) to 67 Olympus 593 built in total.
The Rolls-Royce SNECMA Olympus 593 Concorde Engine - the fascinating full story of the Olympus 593 Mk610 from concept to service

I remember seeing a picture a few years ago of a Vulcan doing a touch-and-go at an airshow and rearranging the tarmac with the. With the mentions that have been made of the little clearance between the nozzles and the ground in landing config, did Concorde ever come close to doing something similar? Was careful consideration taken of the runway surface before doing a touch-and-go at a display?

Well I have to say this is a brilliant thread.

I stumbled upon it by accident and been catching up on it when I had a spare moment and have found it completely riveting and it has whiled away many hours over the past month.

I\x92m ex-RAF and spent the last ten years working as an engine bloke on the T aeroplane & RB199. We were always told there were many parallels with Concorde & the Olympus 593 \x96 TBT/T7 Gauges, Optical Pyrometers, EPC Coils on-engine FCU\x92s, Vapour Core Pump for reheat fuel as well and the like. I attended the RR Manufactures course for two weeks at the Patchway Works and spent a day at the Concorde Museum seeing the similarities with the Electronic Control Units too though Lucas Aerospace made the MECU\x92s or GR1/4 (& DECU\x92s on the F3\x92s).

Also while on the course the distinguished RR Instructor Gent filled up in with various snippets of Engine History too such as the Vaporisers which were fitted to RB199 & the later models of Olympus 593 were originally Armstrong Sidderly designed for the Sapphire, also I learned the whole 15 Stage Sapphire Compressor was lifted completely and fitted to later Avon\x92s as it worked better.

I was at Leuchars in the early 80\x92s and the Open Golf peeps all arrived in one of these magnificent lady\x92s \x96 the visit was notable for several things; someone fired off an escape chute!!! \x96 What does this little handle do on the Main Oleo ??? whoosh ! and after the dusk take off the pilot beat the place up several times in full reheat !!!!

My last place of work before I was de-mobbed was at the RAF Marham Engine bay and I had the good fortune to meet an RR Technician called Phil (second name escapes me) but he was part of the team of RR Controls Engineers during the Hot & High Trials. He said they used to modify the three \x93Amps\x94 for each Engine control \x96 Lane1, Lane 2 & Reheat on the fly and the aircraft often flew with different schedules installed on all four engines \x96 I think the aircraft at Duxford has these still fitted in the racks (??M2Dude??) but that\x92s another Tonka thing too; three control lanes. Were all these Amps combined into one black box??

They are always Amps in RR Speak?? The Spey 202 had \x93Amps\x94 in its reheat system too.

I was lucky to find a job with the TVOC in 2001 until they ran out of money (as they do) and worked to have their flight worthy Olympus 20202\x92s tested at RR Ansty but left before that happened. In fact I don\x92t know if it did happen though it was a CAA requirement. While I was there we were working with Alan Rolfe & Mike Batchelor of the RR Historic Engine Department were offering support too. (593\x92s were their responsibility also !!! Historic !!!) but I think that was unofficial until there was an agreement about the costs.

After that I worked in industrial applications of Olympus (and Avon) and worked on many installed Olympus in power generation but based on the 200 Series \x96 I think the 300 was thought to be too fragile. But I did have a good look at Olympus 2008/003 Still in good working order in Jersey on the Channel Islands with it\x92s Bristol Sidderly Name plate on it. They didn't have Inlet Guide Vanes as the 300's had but just 6 Forward Bearing Supports, hollow with anti -Icing air blown though, controlled by a Garret Air Valve.

I never saw a DEBOW sort of function on the Industrials but there is a critical N1 speed which has to be avoided because the LP Turbine Disc can fail. The Trouble with that speed range is that it is right where the usefull power is produced!!! Was there any Normal Operating Range RPM's which had to be avoided on the 593 ?

Again thanks very much for all the fascinating information here\x92s to another 42 pages!! Sorry to have rambled on so much

Howie

howiehowie93
Welcome aboard and thank you for your kind words; I am so glad you enjoy our thread. You are in good company here also, many of the 'more mature' vintage Concorde people (like me) are ex-RAF. (And some of the pilots were ex-RN also, but no one is perfect ... only joking guys).
It is a matter of pride/embarrassment for me that up to the end of 2003, I'd only ever really 'known' two aircraft; the C-130 and Concorde .
I was really interested in some of the RB199/Olympus similarities; TBP was tried on the development aircraft for engine control TET calculation, but Rolls-Royce were unhappy with the performance and abandoned TBP in favour of indirectly computing TET as a function of T1 (intake TAT) and EGT (T7). (And this meant the removal of the four TBP amplifiers too... we had even more black boxes then.
As for the three 'control amps' you were speaking of, I'm 99% sure that A/C 101, G-AXDN still does have the units you described fitted. The ECUs (or ECAs as they were sometimes called) were a highly complex analog control unit built by Ultra Electronics. They could be quite a headache sometimes in terms of reliability, but would generally perform flawlessly in terms of engine control. As with any analog box, control law changes in the field were not too straightforward and a soldering iron was the flight test engineers best friend here. The Reheat Amp was built by ELECMA (the electronics arm of SNECMA) and unlike some of the other components in the reheat system, was a beautifully designed and constructed unit. Very few reheat failures (and there were many) were attributed to the 'box' itself. The main fragility with the reheat system was the ignition system used (a 20 KV swirl ignitor, which you will see is covered previously in the thread). We (BA/RR) were seriously looking at one point of investigatng the use of 'hot streak' injection as a backup ignition source, which I believe was used in the 199 (?), but it unfortunately never happened. The Plessey DECU that was tried on A/C 202 (G-BBDG) DID combine main engine control and reheat, but unfortunately was never taken up for the production A/C, and so we were left withe the '3 AMPS' as you so eloquently describe. We had a total of THIRTY ONE control units associated with powerplant control on Concorde; might be a little different now methinks ]
Thanks for some of the fascinating engine history snippets you shared with us, although purists might regard it as being 'off topic' I personally think this rather unique thread is all the better for your contribution here,
I think it is great that you are working with industrial Olympuses, all part of the family tree. I will dig out the verboten sustained N1 speed band for the 593, it certainly WAS a fact though.
Thanks from all of us for your contribution here Howie, keep on posting.

Regards
Dude

Thanks M2Dude.

Yes Hot Streak Reheat Ignition on the RB199. Only problem was the Injector was right underneath (or perhaps on top is more accurate! ) of the Reheat FCU and as it jutted out into the Combustor it was often blocking with carbon . so either - off with the RHFCU or disconnet the pipe and try the OM15/Landrover Speedo cable cleaning out trick. There was eventually a test set to tell you if it was still blocked (helpfull - NOT).

I'd left by this time but I was told RR came up with a way of back flushing combustor Pressure to clear it out with some success.

regards
HH93

howiehowie93
The whole idea of adapting hotstreak injection came from our Rolls-Royce rep', who spent many years on RB199 development. We'd even identified the position on the Olympus 593 for the injector itself; un unused start atomiser port, but as I reluctantly said before, it was not to be.
Apart from ignition issues the other main problems were reheat instability and reheat 'coming in with a thump', this particular malady being generally confined to transonic acceleration and not take-off.
The instability issue was caused by either an open circuit/high resistance fuel metering valve tacho (only rate feedback was used here) or more commonly contamination of the RFCU umbilical electrical connector. The connector itself was originally located high up the side of the engine, close to the combustion area, was barely accessable and was a total nightmare in terms of reliability. After a great deal of pressure from us (BA) SNECMA agreed to effectively relocate the connector at the bottom of the engine and the majority of our stability problems almost disapperared overnight.
The 'reheat in with a thump issue was a real beaut'. For transonic acceleration a much lower ratio of Fr/Fe (reheat fuel flow/engine fuel flow) was used than for take-off. (0.45 as opposed to 0.78) and therefore the opening rate of the fuel metering valve required damping, this being achieved by using a metered orifice inside the RFCU that applied a small amount of servo fuel pressure to one side of the valve to achieve the damping. Trouble was, any contaminants in the reheat fuel system would progressively clog up the orifice and kill our daming stone dead; the end result being the FMV banging wide open and hence the 'thump'. The only remedy for this problem was to replace the RFCU. SNECMA, in a truly classic feat of engineering produced a filter across this orifice, in order to prevent it getting clogged. Anyone see a problem with this? Yep, the filter itself would clog up and we got our beloved thump back. The only remedy for this problem was again to replace the RFCU. The contaminants were often as a result of RFCU build issues; this issue was never truly resolved.
I checked and found the dodgy sustained N1 band for the Olympus 593, this was 88-91% N1. This figure was never an issue in service as at cruise ISA -7 and above conditions the N1 was always run at the flat rate limit of 101.5%. Below ISA -7 the intake system would progressively reduce N1 as a function of intake local Mach Number, falling to 97.4% at ISA -24. (The coldest cruise conditions I personally ever saw was ISA - 25 (that's -81.5 degrees C folks) between BAH and BKK.
The controlled N1 at all other 'non cruise' phases was always in the upper 90's, well away from our blade resonance area.

jodeliste and Alpine Flyer
Thank you both for the TSR-2 information, it makes amazing reading (what a truly magnificent aircraft) , and as Concorde's military cousin, discussion here is in my opinion most waranted.

Regards
Dude

Can somebody explain to a "Volts and Amps and Ohms ancient" what "hotstreak injection" is/was (without getting scabrous)?

Many thanks for that story, M2dude, and no problem understanding it that one.

Same here.
Purists be damned.
Concorde wasn't created 'ab nihilo', in a vacuum, as it were.
So, placing her squarely in the aviation world of the time should be part of the thread and the story.

In my own field (avionics) both TSR-2 and Concorde are almost "snapshots" of technology at a given time, a technology which was changing very rapidly.

I may go and rabbit on about that some more, one of these days, but describing what happened in the avioncs/electronics field is always more difficult than the purely mechanical, engine and structure progress.

CJ

PS A few years ago I had a chance to have a close look at some of the TSR-2 electronics in the East Fortune (Scotland) museum.
IIRC a lot of it was Ferranti.
It was an eye-opener as to how much technology had already changed from TSR-2 to Concorde.

Bellerophon
Ahhh this 'other operator' (I'd quite forgotten our code for *** ******). And as for this obviously baseless story .... er yes it did happen. I should really have qualified my post and said 'The controlled N1 as long as the aeroplane was operated CORRECTLY was always at least in the upper 90's, well away from our blade resonance area'. I don't quite recall after the engines were removed post-flight (At Rolls-Royce's insistance) whether the entire LP compressor sections or just the first few stages had to be replaced at the engine overhaul base. In either case it was a rather expensive piece of experimentation.

ChristiaanJ
Certainly my friend (but hey, remember that I'm an old Volts and Amps and Ohms ancient at heart too ).
The lighting of a reheat flame can be achieved in three ways:
1) By using an electric arc ignitor.. the least reliable system, although relatively simple in concept.
2) Catalytic ignition, where the reheat fuel is sprayed over a platinum based catalyst, spontaneously igniting. I recall that although generally reliable, eventually the catalyst compound erodes away and you are left with no ignition source.
3) Hot streak injection (or ignition). I this case a sizable jet of fuel is injected through a single injector placed the the combustion chamber of the engine, a powerful streak of flame then 'shoots out' of the turbine, and ignites the reheat fuel. Generally reliable as long as the injector itself does not carbon up (as our new friend Howiehowie93 pointed out). What amazed me with this system when we were looking at it for Concorde, was that the Olympus 593 designer I spoke to at Rolls-Royce told me that it has a negligible effect on turbine blade life, as the hottest part of the flame does not hit the blades themselves, and also of course it is a very short duration burn anyway (1 - 2 seconds).
And Christian my friend, you should indeed 'rabbit on' here about some of your observations regarding Concorde electronics technology, you have a unique insight here as (probably) the only Concorde systems designer that regularly visits 'here'. I'm sure I speak for many of us here when I say that your experiences are unique and your contributaions are always illuminating. Come on, let's have some Volts/Amps and Ohms

Best Regards
Dude

Greetings.

Service Bulletin 0420 Industrial Olympus Gas Generator \x96 LP Turbine Disc Cracking Safety Related Operational and inspection requirements.
to paraphrase:

Avoid steady operations in the range 5450 to 5850 RPM I believe that 100% is 8000RPM so that equates to 68 \x96 73%. It is ok the accelerate through that range apparently.


There seems to be a lot of history about Olympus LP Discs:
Test House 40 \x96 I think - at RR Ansty still has the deep groves in the brickwork where an engine broke up during test.
From Wikipedia:
\x93XA894 flew with five Olympus engines, the standard four plus an underbelly supersonic Olympus 320 fed from a bifurcated intake starting just aft of the wing leading edge and inboard of the main intakes, in a mock-up of the BAC TSR-2 installation. This aircraft was destroyed on a fire on the ground on 3 December 1962\x94

I read the LP Disc did a QANTAS A380 and decided to leave the engine:
An Aviation Heritage story

So there\x92s nothing new in the world really

regards
HH93

IMHO I'd the simplicity of the design. I have worked on many flavours of Gas Turbines since I left the RAF in 2000, GE, RR, Rustons, (EGT, RGT the same really just a name change every few years and now Siemens) oh and Solar - who I work for now - better not forget them !!

All these engines from other manufacturers have complicated systems to make them efficient:
VIGV's (Variable Inlet Guide Vanes)
VSV's (Variable Stator Vanes)
Bleed Valves
Multi Fuel Metering Valves & other valves to keep emissions under control.

The Olympus - nowt ! Two Spools and a Fuel Valve thats your lot. nothing to go wrong and being an Aeroderivative all the ancillary equipment is either bolted on underneath or away from the engine outside the enclosure.

The only thing I had trouble with was the burner bolts shearing off, 1/4"BSF, if never touched in a good few years !

Was it all still BSF on the 593? That was a Bristols thing - true RR designs are UNC (well Avons are anyway)

oh ! I forgot about the Hot Shot; when I was ground running installed RB199's there was no jump in TBT/T7, you couldn't sense it fire either, the only feel was either the Reheat lighting off with a big roar or the engine going quiet as the Nozzle opened up until the MECU noticed it hadn't lit and closed it again sharpish.

Good eh
Regards
H wie

There's a description and a picture of such an incident in the RR Heritage Book about Olympus. Happened in "Mach Ally" over the Irish Sea, even though the front face of the Compressor was wreaked it could still run up to 85% without surging. Can't remember which 85% though and the book is 4000 miles away from me at the moment.

Regards
H wie

JFK 31L, Kennedy 9 Departure, Canarsie transition, Concorde climb


Speedbird 2, cleared take-off 31L.

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, V 1 , and then, at 195 kts, Rotate . You smoothly rotate the aircraft, lift-off occurs at around 10\xb0 and 215 kts. You hear a call of V 2 but you keep rotating to 13.5\xb0 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\xb0 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\xb0 to maintain 250 kts and keep the left turn going to pass East of CRI.

54 seconds from the start of the take off roll you hear the F/O counting down 3-2-1 Noise whereupon the F/E cancel the re-heats and simultaneously throttles back to noise abatement power, around 96% as you pitch the nose down to 12\xb0 to maintain 250 kts. It is less than a minute from start of roll and already 435 US gallons of fuel have been used.


Speedbird 2, contact departure, so long.

Turning through heading 235\xb0M, the F/E quickly re-applies full dry power as you pitch up to 17\xb0 to maintain 250 kts, but simultaneously reduce the left bank to 7.5\xb0, in order to increase both the radius of turn (to stay on the optimum noise abatement track) and the rate of climb (less bank, higher RoC).

On climbing through 2,500 ft you increase the bank angle back to 25\xb0 left bank and as you approach the 253\xb0 radial JFK, you hear 3-2-1 Noise from the F/O for the second time. The F/E actions the second noise-abatement power cut back, you pitch down to 12\xb0 and, if not in cloud, sneak a quick peek out of your left hand window, looking for the car park by the Marine Parkway bridge, as you would ideally like to pass right over the car park, if possible, as we tip-toe quietly across the Rockaway Beaches, in order to minimise the noise impact on the residents.

Keep the left turn going and intercept the 176\xb0 radial outbound from CRI, and at 5 miles DME from CRI, call for the F/E to slowly re-apply full climb power as you pitch up to maintain 250 kts. We are still in US territorial airspace, below 10,000 ft, and subject to statutory speed control.


Speedbird 2, present position direct to SHIPP, climb FL230, no speed control.

The F/O selects direct SHIPP in the INS and tells you that she has selected that information into your Flight Director. Having checked that the gear lever is at neutral, you call for the Nose Up , and then the Visor Up . Flight deck noise levels drop dramatically as the Visor locks up. Now more than 12 miles away from the coast, we are clear of US speed control requirements so lower the attitude to 9\xb0, accelerate to V MO , currently 400 kts, and ask for the After Take Off Checks.


Speedbird 2, present position direct to LINND, climb in the block FL550-600, accelerate Mach 2.0

Call for the Climb Checklist at Mach 0.7, which will trigger the F/E to start pumping fuel rearwards to move the CG aft, then when he's done that, straight into the Transonic Checklist . Maintain 400 kts IAS, and around 24,500 ft, at M0.93, ask for the re-heats back on, in pairs, and raise the nose by 3\xb0 to maintain 400 kts as they kick in.

Precise, smooth flying is required through the high drag transonic region, as the mach meter creeps up towards Mach 1. A sudden flicker on the VSI and Altimeter confirms that the shock wave has just passed over the static ports, and the aircraft is now supersonic. A quick glance at the elapsed time indicator shows that you\x92ve been hand flying for just over 9 minutes since the start of the take off roll.

Another fun start to a day in the office, and to think we got paid for doing it!


Best Regards

Bellerophon

PBL
As far as the Autothrottle side of things (you know, the throttles actually MOVING in response to autothrottle action, how novel ), that was designed by the Elliot part of the Anglo-French AFCS consortium. (This then became Marconi-Elliot, and then GEC-Marconi, and finally part of BAe Systems). I doubt very much if this is in anyway connected with Airbus at all. (I know,...Duh!!).
As far as the Concorde engine power control philosophy, well this was Rolls-Royce, through and through, with some BAe input, so again I think you can rule that out too.
Basically PBL, I would say that in answer to your question, we can say that they were definately not, thank goodness ... (Naughty boy, Dude ). Bearing in mind of course that the current Airbus philosophy can be traced back to the early A320s.... not a Roller in sight there.

Best Regards
Dude

Well as that well known lady Randy Mice-Davies said " They would say that wouldn't they" (That shows my age!)

Seriously, they couldn't possibly know that the new nozzle fell short of it's design promise. There was no means of measuring thrust in flight installed on the aircraft and even if there had been the possible precision would not have allowed one to make such judgement. The only certain thing in aircraft design is weight, and that could be established unequivocably - it was lighter than the original. Any aerodynamicist looking at the two designs could tell you that the drag of the TRA (Tuyere Reverse Aval) was going to be less than that of the prototype nozzle, but establishing an exact value was another matter.

For the record. the idea of a new design originated in Sud Aviation. The development of the design was entrusted to a joint BAC/RR/Sud/Snecma team (I was one of that team, so maybe I am biased!). Snecma were not very keen on the idea of a new nozzle, largely from pride and a strong NIH factor, but one could not in fairness blame them for any performance shortfall - it was a joint effort.

CliveL

I've pulled this quotation out at random from what I have found a rather disappointing sequence of postings. I could write reams about this (and like everyone in this thread I would write as a Concordophile), but I won't - or at least I will try not to. In general I'm with Christian on this, and for the record I think a few 'counterfactuals' should be recorded. I am not trying to reopen a sterile debate - as CJ has said irrevocable decisions have been made and the subject is done and dusted. However, let us remember that:

G-BOAF was, and is the property of BA; BAe and now AI are merely caretakers.
AI's statement cross-posted from the Heritage website strikes me as a very reasonable statement; we found that your roof is leaking, if you don't get it fixed it is going to get worse rather rapidly; if you (BA) agree and will pay us to do it we will take it indoors and fix it. I don't see any sinister intent here, and given the weather we have had in the UK over the past weeks it must be regarded as a happy, if fortuitous decision!
Those who know Filton will also know that there is nowhere that Alpha Fox could be stored under cover except in the hangar where she was first assembled. They will also know that this hangar is buried in the centre of the factory and nobody, in a post 9/11 world, is going to give more or less unrestricted public access to somewhere containing a lot of valuable real estate! So when BA took the decision to locate AF at Filton it must have been in the knowledge that she would live in British weather until some form of shelter could be organised.
That it has taken so long to (fail to) organise such shelter is regrettable, but the blame can hardly be uniquely allocated to AI. BA own the aircraft, BAe/AI had a 40% share in building the airframe, RR a 60% share in building the powerplant. IMHO they should all have chipped in to construct some sort of shelter - it was never on the cards that local enthusiasts could have raised enough in a short time.
Although 'Dude' says that all the UK airframes were left out in the weather, this is not exactly true is it? 002 at Yeovilton (certainly) and 101 at Duxford (I think) are under cover and receive lots of TLC. It is at least arguable that these early airframes have more historical significance than Alpha Fox.

So far as AI's decision to hand back the C of A is concerned, they would have already recognised from the post-Gonesse activity that most people with sufficient expertise on the Concorde design were retired (or worse!) They have enough people to keep a subsonic aircraft going, but Concorde would, I think, require additional experience. AI management would certainly have consulted AI Engineering about this, and I have to say that the then Head of Engineering was someone I know well. He, like me, worked on Concorde in the early days and he is definitely not antiConcorde. I for one would respect his decision.

So far as the decision to stop services goes, we all knew they would be cut off sometime.the only question was when. When we were designing the aircraft the general feeling was that she would stay in service for about 30 years, but we also feared that it would only need one fatal accident to bring the whole lot crashing down. [Incidentally, it was that latter philosophy that made us (we hoped) ultracareful with airworthiness issues] In the event it was 28 years and one accident.
Even before Gonesse AF were losing money on their Concorde services. One might have thought that they would stop right away, but I suspect that a combination of Gallc pride and politics ensured that they would carry on.
But eventually there came a point where, on an airline losing money and in a recession, an unsentimantal and yes, generally unsympathetic, management would have to say enough is enough.
What else would you have them do? Continue to fly loss making services so that their rival BA could go on with their profitable? operations? One would have to say 'Get real!'
Once AF had decided to stop, what do you expect of AI? They are a company with a duty to make profit for their shareholders. OK, they had a duty, also to support in service aircraft, but that duty does not extend to doing that at a loss. With AF out of it therefore AI had no alternative but to ask BA to shoulder the full bill. I have no doubt that when BA declined to do this AI breathed a huge sigh of relief, but at the end of the day the decision to stop all Concorde services was above all an AIRLINE decision.

Sorry to go rabbiting on, but it is a subject that arouses strong emotions!

CliveL

A pot pourri of responses after my Christmas reading!

This actually is interesting in that the n umbers show one of the fundamental features that made the Ol 593 such a good choice. If you look closely at the TO and cruise values you will find that at TO the overall compressor pressure ratio is 13.5 the compressor exit temperature 460 degC and the turbine inlet temperaure is 1152 degC. In cruise the pressure ratio is 10.5, the compressor exit is 565 degC and the TET 1100 degC.

Somebody, I can't find the exact post, was asking whether the elevated cruise total temperatures affected engine life, and here we see why this is so. As Christian said in another posting, when you compress air it gets hotter - from 21 degC to 460 degC at take off and from 127 degC to 565 degC in cruise. A fundamental limit on engine operation is the turbine entry temperature. Not only does it affect the maximum TO thrust you can get but also the continued exposure to cruise TETs has a very big effect on engine fatigue life, and engine manufacturers have shown extremes of ingenuity when developing new materials and ways of cooling the blades to increase allowable TET.

The problem with supersonic operations is that you start from an elevated intake delivery temperature so that when the flow exits the compressor it is already very hot 565 instead of 460 to be exact. But the maximum temperature one can stand for fatigue reasons is limited, therefore the amount of fuel you can pour in must be limited also, and the thrust you can develop per pound of airflow is roughly proportional to the fuel input/temperature rise. To get any sensible cruise thrust then one must squeeze the cruise TET as high as you dare for fatigue reasons but also you need to keep the compression ratio down so that the temperature going into the combustion chambers is as low as you can get away with. This tend to drive engines designed for extended supersonic operations to having a low pressure ratio. This is against the trend in subsonic operations where compression ratios have been steadily increasing along with bypass ratios.


The net result then is that the engine must be designed with a low OPR and must operate with cruise TET much closer to its TO TET value than would be necessary, or indeed desirable, on a subsonic design.



Actually, here, as on some other apparent carry-overs, one should look at the equipment supplier rather than the aircraft manufacturer to trace continuity. Here we have Messier supplying Concorde's gear and Dowty (OK they are now part of Messier) supplying the A330. And having worked on both, I seem to remember that the means of doing the shortening are quite different.

Quote:

Originally Posted by Brit312

The Britannia and now you are talking about the love of my life and yes I do remember the story of the nose and visor selector, but we have forgotten the most obvious. Where do you think they got the idea for the control column from

Yes, they both came out of the Bristol drawing office. One minor anecdote: the 'ramshorn' stick was a novelty to the Concorde flight test crews but they got to like it, or at least put up with it. All went well until it came to the time when Dave Davies, the ARB Chief Test Pilot, came to put his rubber stamp on the aircraft.

Concorde's seats, just like those on your car, could be moved back and fore to get your legs on the pedals and up and down so you could see over the bonnet (sorry, instrument panel). The control column of course stayed in one place, so the relationship of the 'horns' to ones thighs varied with ones height. Andre Turcat was about 6ft 2in, Trubbie and the others of average height. The smallest regular pilot was Jean Franchi at, I suppose, about 5ft 7 or 5ft 8. No problems. But Dave Davies was short like me and he found that he could not get full back stick and full aileron because the ramshorn fouled his thighs.


Consternation! Completely unacceptable! I don't know what arguments they used to convince him it was all OK really, but it got through certification. I would certainly be interested to learn from the pilots in this group as to whether it was ever a problem.

Quote:

Originally Posted by exWok

........which was one reason it was so important to touch down with the wings level - even a very small angle of bank could result in bucket contact as they translated to the reverse position. It was a surprise coming to Concorde to find it was even more restrictive than the 747 in this respect

I can't resist this one!. Has anyone ever noticed/wondered about the tiny bit of the outer elevon that has been chopped off? That was my first real input into the design as a young erk looking at variability of touchdown conditions and coming to the conclusion that if the pilot got into trouble and was trying to pick up a trailing wing with too much AoA as well then he was likely to hit the ground with the downgoing elevon. I persuaded my boss that this was so and we made a small adjustment.
In self defence I am going to plead that this was well before the days of the Type 28 nozzle, so the issue of buckets contacting the ground first never came up!

Quote:

As far as your point about the prototype engines; they were way down on thrust anyway, (even without the 'help' of the silencers), produced more black smoke than a 1930's coal fired power station.

To the point where an American Airline maintainance engineer, watching a prototype taking off and with full benefit of being located strategically for maximum sideline noise, remarked on what he described as 'visible acoustic radiation'

On another occasion, it was reputed that Stanley Hooker, watching a TO in the company of HRH the Duke of Edinburgh, remarked that "You know Sir that that noise represents less energy than it takes to boil an egg". to which he got the reply "Then I must congratulate you Sir Stanley, on producing so much noise for the expenditure of so little energy".

Quote:

Originally Posted by CJ

One example : in theory the aircraft did weigh 1.2 % less, so the lift was 1.2 % less and the drag was 1.2 % less, so the fuel consumption was less too, so did Concorde have another 50-odd miles range thrown in 'free' by flying higher and faster than it's low-down subsonic brethren?

There was an effect and in consequence the aircraft performance brochures were formally calculated for north/south flight. Pity really, it would sometimes have been nice to be able to fly guarantee performance demonstrations in the most favourable direction

That's enough for today!

CliveL