Posts about: "Afterburner/Re-heat" [Posts: 110 Pages: 6]

Concorde had a very advanced HUD fitted. It was a spring-loaded wire frame (a bue transparent plastic thing on 'OAG) which you could flip up in front of you to help judge the landing attitude. With final attitude about 11 degrees and secondary nozzles scraping the runway at (from memory) about 12.5 degrees attitude control was key.

Three-engined ferrys were approved. Went through it on the sim, and this is only from memory but you set full re-heated power on the symmetric pair, and the assymmetric engine at 75kts. "Power Set" was called slightly later than normal (130kts). Any re-heat failure before V1 = RTO.

There were loads of complex additional issues to go through at planning (the 3-engine ferry manual wasn't the thickest on the fleet - but it was thick enough!) and I don't think I'd have been too keen on doing one (I was never asked, and I don't know of any Concorde having done it - more "seasoned" fleet members may know better!): I think it was a slighly more critical proposition even than doing it on a blunty, and most guys I know have reservations about it on their fleets too...

NW1 and ChristiaanJ
Ahh yes, the super hi-tech 'HUD'. It was right up there with the 'eye level datum' indicator and not to forget, the reheat capabiliy indicator in terms of sophistication. (Extremely reliable though ).
As far as 3 engined ferries went; well NW1, not sure if you'd call me seasoned or just just clapped out and wrinkly, but it did happen a very few times in days of yore, mostly from SNN back to LHR. There were at least two; OAF in 1980 when she had the infamous LP1 blade fail (and Monty Burton's immortal words during the 'event' "what *** ing drill?). The second one that I can remember was OAA in 1991 when there was another far less serious compressor blade failure. In each case for the ferry flight, the broken engine was 'swaged' to prevent it windmilling and the aircraft would be flown back to the LHR garage by a management crew. There was however another required ferry measure as well as the engine swaging, this measure was to prevent the good engines going into contingency, due to the very slightly flamed out dead 'donk'. This procedure required the Engine Speed Unit to be removed from the electronics rack and a special jumper plug fitted in it's place (without the jumper fitted the start switch would never latch in. In this case also the E/O would also need to manually disengage the start switch at 25% N2). I have to admit that I never in my life ever saw this jumper plug, and in the cases that I can remember the aircraft departed SNN with the three engines at contingency. I remember that the case of OAA back in '91 most certainly was; I was flown out to SNN equiped with a pile of circuit diagrams and test boxes to investigate what we all thought was just a surge related engine shutdown. only to find a slightly more hairy state of afairs, with a very broken engine indeed. As a matter of interest, this particular failure was the only one ever in the history of Concorde in BA attributed to the engine having run for a protracted time in rotating stall. (This had happened on the previous day). A lot was learned by both BA and Rolls Royce after this event, and this failure never occured again.

Dude

Can I just throw a comment in ?

In about 1992/1993 [not sure of the date now] I was lucky enough to exchange my JED->LHR BA Economy ticket for a Concorde Ticket for 400 notes.

All I can really remember about the flight is the noise, acceleration and comfort [not to mention the stunningly good on-board service Landlady]. I got a quick cockpit visit and have a treasured photo of me crouching between the pilots.

I know it's a long shot but did anyone here crew on one of the flights to Jeddah ?

Oh, I forgot the "two shoves in the back" presumably from inboard/outboard application of reheat to go through the sound barrier.

Thanks for a wonderfully informative thread - it's so heartening to see so many people who haven't forgotten this aircraft.

Landroger
SSBJ is Supersonic Business Jet Rog', there have been a few designs but the most famous (and had the most potential) was the Sukhoi-Gulfsteam S21. This aircraft would carry about a dozen passenges at Mach 2.2, with a range of 4,500 miles. Gulfstram pulled out of the partnership; there werer serious doubts about the viability of the Russian engine as well as serious aerodynamic issues too.
I would not personally utter 'Concorde and Tornado' in the same breath Rog; you need to carry this 6 tonnes over more than several HUNDRED miles. There is absolutely no comparison between the performance of Concorde and the Tornado I'm afraid, you'd need to base any military adaption on a far better design than that.
Although design of the powerplant for any future SST is pivotal to the whole design, you still need an aerodynamic model with a significantly higher lift/drag ratio than Concorde to make the project viable. And as good as the SR-71 was (I'm one of her biggest fans) she was still using afterburning/reheat at Mach 3 cruise.
galaxy flyer
Great to see you back here GF. I DO hope that you are wrong about mini-skirts
You are so right about the massive industrial collaboration required; it seems that there was so much more of a 'daring spirit' in the 1960's, makes you wonder where all the balls have gone today. (Oh I know, there are so much more deserving causes than aviation for us to spend BILLIONS of $'s and \xa3's on today).
Nick Thomas
No need to apologise for any thread drift Nick; this is such a diverse thread now; your points are perfectly valid here. And thanks for your kind comments again Nick; CJ the rest of the guys and myself are more than happy to bore the socks off of you and all the other posters and readers.
hoofie
So glad that you enjoyed your Concorde experience. The Jeddah flights were a fairly brief 'experiment',it would be great if one of my pilot/flight engineer friends here did a trip, we'll soon know. The double 'shove in the back' would indeed as you say have been the inboard/outboard reheat selection. Glad you are enjoying the thread, it is certainly bringing back memories for me about this seemingly eternal aereplane.
jodeliste
No problem Rod, I think most of us here agree about that one. A terrible waste and a giant leap BACKWARD in aviation.

Dude

Landroger
Come on Rog, let's not be silly now. I was not 'upset', and you can use the 'T' word any time you feel that you need to lad. It's just that you used a very poor example to use when, I don't know what your point was anyway, comparing Concorde with any other aeroplane.
The J58 powerplant design for the SR-71 is superb, and considering the early 1960's era that it was developed, was nothing short of astounding.
For Mach 3 cruise air is bypassed around the engine core and fed staright into the afterburner duct, where it supplied the afterburner directly. Still a remarkable design though, even now.
Oh she didn't; she just leaked. (not on the same scale as the SR-71 though).. If you were nuts enough to walk under a fully fueled Concorde without an umbrella you often got quite wet and smelly. The leaks were 'drips' and not running streams, and maximum permissable leak rates were mandated and controlled, but if she became particularly 'drippy' it was straight back to the hangar for tank re-sealing for our Concorde. The fuel tanks were sealed using liquid viton rubber, the idea being that the viton when it solidified would filll in all the nooks and crannies of the tanks. Controlling leaks was one of the most time and labour consuming aspects of Concorde maintenance, to get in and seal some of the smaller tanks was challenging to say the least, and some pretty small chappies were required for some of the tank areas.
I still remember that when we were building Concorde, this idiot of a production manager at Filton (the same one that was responsible for the debacle of G-BOAD sitting on her tail) insisted that the fuel tanks were filled with fuel as soon as the tanks were completed, whether the sealant was dry or not. I still wonder how much of the in-service leak maladies could be directly attributed to him.

Dude

Fascinating stuff again Dude, I'd never realised that even that leak rate existed on Concorde but then maybe other airliners leak a bit too, I don't make a habit of walking around under them (more's the pity).

As for the SR-71, the construction was a bit like a lot of ribs with sliding clips that attached the skins to them, hence things could slide about to cope with the heating at Mach 3+. Kelly Johnson often referred to this as his "Mach 3 Ford Tri-motor".

The fuel used (JP-7) had a tendency to rot the wiring in the aircraft, so they were re-wired quite often during their lives. All Sleds sat in pools of fuel when hangared, unless they were totally empty.

Refuelling was usually carried out at about 33,000 feet, and as the tanks filled it became necessary to light minimum afterburner on one engine to maintain contact with the tanker. The nose was always yawed the same way because only one of the windshield panes was de-misted so this side was always used to maintain sight of the tanker's underside.

After tanking a descent was commenced to about 26,000 feet to help with acceleration to supersonic speed, as far as I am aware all supersonic flight was made with afterburner selected.

I remember reading some time ago that fuel consumption was in order of 8,000 US gal per hour. Not sure if that is an average or whether it covers only Mach 3 cruise.

Mr Vortex
First of all, 'welcome aboard'; I'll do my best to answer your queries.
The area of the primary nozzle Aj, was varied for 2 'primary' purposes :
a) To act as a military type 'reheat' or 'afterburning' nozzle; opening up to control the rise in jet pipe pressure P7, as reheat is in operated.
b) To match the INLET TOTAL TEMPERATURE RELATED (T1) speed of the LP compressor N1 to the HP compressor N2 against a series of schedules, ensuring easch spool is as close as safely possible to its respective surge boundary, (with a constant TET, see below) and therefore at peak efficiency.
Now, in doing this a complex set of variables were in place. As the nozzle is opened there is a REDUCED pressure and temperature drop across the LP turbine. This has the effect of enabling a HIGHER N1,as less work is being done by the turbine. Also the change (in this case a decrease) in the temperature drop across the turbine will obviously affect the turbine entry temperature, TET. A closing down of the nozzle would obviously have the opposite effect, with a DECREASE in N1 and an INCREASE in TET.
In practice at a given T1 there was always an ideal N1 versus N2 on the control schedule (known as the E Schedule), the TET staying more or less constant from TAKE-OFF to SUPERSONIC CRUISE!!
As far as noise abatement went; when reheat was cancelled and power reduced after take-off, an E Schedule known as E Flyover was automatically invoked. This had the effect of driving the primary nozzle nearly wide open, reducing both the velocity of the jet efflux and in essence the noise below the aircraft.
The real beauty of this primary nozzle system was that it really did not care if the engine was operating dry or with afterburning ('it' did not even know). P7 was controlled against a varying compressor outlet pressure, the variable being controlled by a needle valve operated by the electronic engine controller. (If this is unclear I can post a diagram here that shows this control in action).

As soon as I receive back the majority of my technical notes that I have out on long-term loan (I've requested their return) I will post a schematic here. But for now; The tanks were vented to atmosphere via tandem vent galleries, the two vents openings being on the left hand side of the tail-cone. At an absolute static pressure of 2.2 PSIA (around 44,000') twin electrically operated vent valves, also in the tail-cone, would automatically close; the tanks now being pressurised via a small NACA duct on the right side of the fin. A tank pressure of around 1.5 PSIG was maintained by the action of a small pneumatic valve at the rear of the aircraft. There was massive protection built in to guard against over-pressure (eg. if a tank over-filled in cruise).

I hope this answers some of your queries
Best 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

Mr Vortex
Not quite; remember that the N1s and N2s in the E SCHEDULE graph are non-dimentional. ie. they vary with temperature. As the temperature rises (with increasing Mach Number) the scheduled spool speeds increase. What really happens (I did not explain it correctly first time) is that the much lower N1 demanded by the use of E LOW at high speed results in a much further closed primary nozzle than normal, pushing up TET (and EGT) and we run hard into the EGT limiter, which claws fuel flow off, to the extent that the ramps and spill doors come down to their preset limits, almost as if there is a flame-out. The net result is a huge reduction in thrust. The condi was formed as the primary nozzle naturally took up a near fully open position in supersonic cruise and the wide open secondary nozzle buckets completed the picture. The schedule used here was E HIGH. I've noticed a couple of errors on the graph, the main one being that E HIGH is used with reheat off but with Vc > 220 KIAS
Apart from being set as a variable limit, EGT normally played no role in the control loops (there were 2 loops, the 'governor' and 'positioner' loops). P7 played no part whatsoever in any case, the main variables were; N2, throttle valve position, throttle transmitter position, T1, total pressure and static temperature..

Feathers McGraw
Oh nooooo... I've been outed
Best regards

Dude

In 2000 I was on my way to Helsinki in a Finnair A321 at Heathrow taxying out towards 28R when looking out of the windows we realised that a Concorde was passing to the left of us. Just at that moment the ceiling screens folded down and the forward facing camera powered up, showing us the whole of the Concorde as it turned onto the runway and spooled up. The whole of the fuselage of our 'bus was rattling away, and then as the noise decreased we were cleared to line up ourselves and the screens showed rapidly receding reheat flames through a cloud of exhaust smoke. Despite being cleared to take off immediately, we were naturally left well behind, I could just see the Concorde climbing out to the west as we turned north and then east to head off across to the North Sea.

No prizes for guessing which flight I would have preferred to be on....

speedbirdconcorde
5 seconds I know, but it does at least compensate for my other screen hoggings.
Some really nice shots of G-BOAG and the SR71. (I particularly love the 'business end' shot of the J-58, showing the 4 afterburner rings).
I last visited OAG in Seattle about 5 years ago and the exterior had really suffered from the elements, being parked right next to a highway near one of the most beautiful but wettest cities in the USA. (Boeing told me that they were planning a re-paint, don't know if it ever happened though). The interior however was absolutely immaculate, thanks to the pre-conditioned air being pumped through the entire fuselage. (Now THAT'S the way to do it ).
And as for the last photo..... (I laughed so much I almost fell of the chair).

1965 BEA
Nice clip, pity it's an ambedded Flash movie. It is at a good resolution however, if you zoom in the web page it's really quite good quality.

Regards
Dude

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

A couple of observations and a questionette, if I may? First, I'm feeling quite pleased with myself that I have largely understood the latest phases of discussion, re: Reheat Ignition and N1 resonance! To be fair I was a bit puzzled about 'Hot Streak' until Dude explained in a slightly different way. Then my first thought was; 'Cor crikey, isn't there enough heat on the turbine blades already?' It seems not, but it does raise the issue of TBE (TEB?) injection, a la SR71? I know the Blackbird used rather different fuel (JP8?), but is there not a similar chemical that would have done the same thing? Perhaps it was a reluctance to use 'exotic' chemicals in a civilian aeroplane?

The resonance issue is quite interesting, in that it appears to have affected all models of Olympus and was at roughly the same rpm on all. I take it that any attempt to damp specific frequency resonance would have adversely affected the performance?

Which brings me to my questionette - given that Bristol-Siddley created the original design when jet travel was still quite novel, what was it about the Olympus that made it so capable in so many guises and for so long? Not only Concorde of course, but TSR2, warships and fixed electrical generators.

Roger.

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

Landroger
The great thing about the OLY593 was the high specific thrust (in relative terms the Olympus is a tiny, compact design), it's growth potential/high potential mass flow. A bypass engine is not really ideal for supersonic cruise, and given what was available in terms of two-spool turbojets in the 1960s, the Olympus was the obvious choice for both the TSR-2 and Concorde alike. As far as for ships and power stations, well a turbojet is always going to be favourite, as all the gas energy is contained in the jet efflux; this can be efficiently transferred to the load in question by a gearbox coupled to the HP spool.

howiehowie93
Well the 593 did require a primary nozzle to match N1 against N2, bur apart from that she was a study of deceptive simplicity and elegance.
No mate, generally BI-HEX AF.
This really is fascinating stuff Howie, thank you. As I alluded to a few pages back, the primary nozzle on the OLY593 opened in response to the rising P7, kind of 'after the horse has bolted' in a way. To maintain the correct scheduled value of N1, the control system set, via a needle valve, a finite ratio between P7 and P3. As reheat lit as P7 attempted to rise it upset this ratio and the primary nozzle was opened in order to restore the aforementioned ratio. (Nozzle opens, P7 falls). When reheat was cancelled the opposite happened, and the nozzle closed sharply to prevent N1 overspeed.

Tom355UK
Glad you are enjoying our thread, and thank you for your kind words. (But apologies to your good lady wife though ).
Jeepers Tom that is one hell of a question. Assuming there was a market for such a venture (personally not sure right now) I think you are looking at BILLIONS of $, and for this reason alone I think you'd find that a multi-national/continental effort would be required. There is little doubt that technology is not the major barrier here, but economics and political will. (Nice thought though, I do agree).
As far as a powerplant goes, well the PW5000 is a really superb engine, although well down on the thrust requirement for an 'NG' SST. More likely I would have thought would be e development of the Olympus, there was/is still such an enormous amount of potential in this basic design. (But who knows, this is all pure speculation anyway).
And have no fears about posting here Tom, most of us are quite happy to answer away (We've said before that there is no such thing as a stupid question; you are most welcome here ).

DavvaP It really did not matter what airframe we used for the test flight; the sole purpose was just to find out just what effect (if any) the tank liners had on the performance of the fuel system. (The handsome chap who you see on TV most, installing the liners, Mr Marc Morley left BA and now resides in Australia).
I am honoured to say that I was lucky enough to be onboard G-BOAF for that flight from LHR-BZZ and as far as I could tell, the liners had no impact whatsoever. One amusing part of the flight was when we deliberately allowed tank 3 to run dry and see just what the indicated fuel quantity was as #3 engine flamed out (we were subsonic at this point of course). The gauge slowly crept down (in order for the tank to to run dry, the tank 7 & 8 transfer pumps were switched off) and we all watched in eager anticipation/dread....... as the counters reached zero weeeeeee... the engine flamed out. I am being completely honest here, the engine wound down EXACTLY at ZERO indicated contents).
Those 7 aircraft really did look magnificent I know, it was just sad as to the reason they were all lined up there.

Mr.Vortex
Well she was a delta without a tailplane, so the short answer is 'yes', but remember that we used fuel to move the CG backwards and forwards for long term trimming.
OK, this is a little complicated, so bear with me. The intake had a finite limit, in terms of the mass flow that it could deliver to the engine and so an automatic N1 limitation signal was transmitted from the intake 'box' (the AICU) to the engine 'box' (the ECU) full time above Mach 1.6. Now this limitation was referenced against TEMPERATURE compensated N1, ( N1/ \xd6 q) and at normal ISA temperatures this limit was above the 'normal' 101.5% N1 running line. (The lower the temperature, the lower the effective limit became). At ISA -7 the limit now became less than 101.5% N1, and so the demanded value of N1 was reduced to this value. But this limit signal was always there, it's just that at normal temperatures it was effectively ignored by the ECU. If this limitation signal failed for any reason, the AICU would detect this by way of the ramp angle becoming uncomfortably close to it's MINIMUM variable limit (this limit was scheduled as a function of intake local Mach number) and an amber light would illuminate on the associated N1 gauge, along with an amber INTAKE master warning would illuminate (plus an audible 'BONG' from the audio warning system). The only course of action was to manually reduce throttle setting away from the Mach 2 norm of maximum, in order to reduce N2, and consequently N1 and mass flow demand. There was in intake pressure ratio indicator at the top of the intake control panel that would show where the power setting would have to be set to. It was an indirect indication of intake shock geometry.
This manual N1 datum reset control was only used during flight test trials into just how much N1 would have to be controlled/reduced at low temperatures in order to give optimim intake geometry. It had absolutely nothing to do with afterburner/reheat and had no place in the production aircraft as all the research was complete

Best regards to all
Dude