OMG Clive yes, sorry about that. I remeber it well now, I just did a search and posted up my original.

Take off reheat selection
 

I seem to recall from my two take offs in 1978 or 9 that all four reheats were selected in pairs for take off and lit while holding on the brakes, with a preamble/warning over the PA that this was what was going to occur. Is this another indication of my failing "little grey cells" or did the procedure change?
Same PA announcement and lighting in pairs also occurred when going supersonic.

For take-off reheat was selected (armed) on all 4 engines together, and certainly not in pairs. (As was stated previously, once 81% N1 was reached the reheat light-up sequence was automatically initiated). You would not wind up on the brakes either, the carbon brakes were extremely sensitive to overtorquing. For transonic acceleration however you are quite right about the 'burners in pairs' bit.

Fatigue
 

I saw some questions earlier about performance but that's pretty well documented. I was wondering more about for how much longer ( if there had been no retirement )??


Was there a Fatigue Index as other aircraft of the same era – I only know of the Tornado in this respect: a long calculation was made per flight taken of flight duration, G readings, TO weight, Landing weight etc leaving a small number of 0.0000x per flight. Then added to the current FI to give a forecast of life left. If anyone remembers the Tornado 25FI Update Program debacle in the 90's ???


So how was the Concorde's airframe life calculated ?? Flying hours or perhaps pressurisation cycles ? Did a higher altitude effect anything since there would be a higher differential pressure??


On the Engine side, I remember an Olympus Service Bulletin describing the calculation of Fatigue Cycles for the Oly 200:- There was a calculation with several parameters but instruction to disregard below a certain figure, 85% to Max RPM & back was a regarded as a cycle and the LP Turbine Disc was the component with the lowest number of cycles before the need for overhaul.Was this still the case with the 593 ??

I can't answer for the engines, but the airframe life was going to be limited by thermal fatigue cycles. There was an on-going programme of testing at RAE Farnborough where, from memory, 21000 cycles had been accumulated by the time it was shut down. The airworthiness authorities were demanding a safety factor of 3 because nobody had flown under that sort of limit before, so the theoretical life would have been 7000 flights.

Not so bad as it sounds in calendar years, as the annual utilisation of any one aircraft was very low, and there would also have been scope for life extension by applying certain modifications to the fuselage.

M2dude

What does self-starting mean exactly? Does it mean self-stablizing?

Ironically, that idea worked on piston-driven aircraft. The P-38 actually used a left-hand and right-hand prop; in order to make the prop spin in the desired direction, one of the V-1710's were installed backward.

Hi again Jane-Doh. Self starting meaning (at least to my non-aerodynamicist avionics infected brain) that the shock system will establish itself perfectly without specific movement of the variable surfaces. Similarly it will not experience the phenomonem (unstart) where the whole shock system will be violently expellled to the extent that it can not tbe safely re-established without changing both the engine power setting and the variable surface position. (This whole thing being the 'train wreck' phenomen :yuk:).
That was interesting stuff about the P38, I must admit I'd not heard that one. (Makes sense I suppose though, provided that the engine can be easily be re-positioned in such a way).

I had to look it up on Wikipedia::ugh:

Lockheed P-38 Lightning - Wikipedia, the free encyclopedia

sorry for the thread drift. :=

regards
Howie

Modern day contra-rotating props. (Shacks don't count.)

http://www.pprune.org/military-aircr...ml#post6231665

CliveL
The RELIFE programme had already taken the aircraft to 8,500 cycles, and the escence of RELIFE 2 had already been agreed when the maggots pulled the plug in late 2003. My own personal guess is that we'd now be looking at RELIFE 3 within a few years if we were still operating. It always really was a case of 'how long's a piece of string' as far as how long the aeroplane could be kept flying.

If I may be permitted to tread drift a bit re engine rotation effects: prop-driven aircraft suffer a range of unpleasant effects that jets don't. Not least is the prop slipstream effect; the propwash spirals around the aeroplane and pushes on the fin inducing a turn. This is at its worst at take off, with no slipstream and high power; even our Chipmunk needs a bootful of left rudder to keep straight when full power is applied at the start of the take-off roll. A really powerful aeroplane like a Spitfire cannot use full power until there is sufficient airspeed to make the rudder effective enough to keep straight; one reason why later Spits had contra-rotating props.

Then, for a taildragger like the Chippy, there's the 'assymetric blade effect' or 'p' factor, where with the tail down the down-going prop blade produces more thrust than the up-going one. And the engine torque effect particularly noticable on soft runways with powerful aeroplane where one mainwheel tyre is pushed into the ground with more force than the other, and finally the gyroscopic swing induced in a taildragger as the tail comes up and the prop disc is tilted to the vertical.

All of these effects are cumulative, and it's one reason why tail-wheel prop pilots learn to use their feet! All are obviated by contra-rotating props or, for twins, 'handed' engines which rotate in opoosite directions to each other.

When I had a share in a Yak52 I used to use the 'engine torque effect' to steer the aeroplane on Barton's muddy winter surface; using the conventional method (braking the appropriate mainwheel; the nosewheel was free-castoring) didn't work as the (quite thin) wheel would just lock and slide along, not inducing a change of direction at all. But whack on a fistful of Vendeneyef and 360hp would dig the right main into the ground and she'd turn right. Pull the power off suddenly and the left main would dig in, turning her left. Worked a treat!

M2dude,

Thanks for that info Dude - you were still working on the beast long after I left it!

Tomorrow is the launch for the 7th edition of Chris Orelbar's book and I hope to meet a few old friends there. Maybe something interesting will emerge:ok:

Hi all,

I have read through some book and it said that in cold ambient condition [ISA -15C or less], the intake can suffer a supercritical condition and I did look up a picture of intake in supercritical condition and it show that the shock wave seems to get "sucked" in and the shockwave isn't concentrate at lip area. I don't understand that if the aircraft is travelling at M2.0 then the air passing through the engine should have the same mach no and hence the shockwave should be identical to the normal condition but it isn't. Can some explain this for me please.:8

Best regards

Not quite the case, although the potential for a very rough ride was always there. Bill Weavers accident was the only one that involved an unstart, and was due in no small part to the test nature of the flight - CG out the back door. In Bills own words,

Concorde G-BOAF heading for the London Eye?

http://heritageconcorde.com/?page_id=7739

As a Concorde enthusiast since day one, I'd like to express my sincere gratitude for all the inside info you guys have shared with us outsiders in this thread.

Keep it up, please... :ok:

Concorde 202
 

She was a a test airframe only, although in circa 1985/86 we did look at modifications that would bring her up to production aircraft standard. The modifications required to the powerplant alone (mainly engine and intake control logic and management) were truly massive, as well as other things like engine instrumentation and other systems' control management. The total cripler however was the cost of a TOTAL RESKIN of the forward fuselage section (Component 30, made at Brooklands). The production series aircraft had a thicker skin here, and we were told that the CAA insisted on this being done as part of any conversion to airliner standard. Costs of around £30 were being banded about for bringing the entire airframe up to production aircraft standard. Also of course she had an MEPU when flying rather than a HYRAT for emergency power and of course a large flight test observers position.
I worked on 202 personally quite a bit during the mid to late 70's, but she never remotely 'felt' like a real production aircraft. Even aircraft 204 (G-BOAC) in her pre-route proving days was a radically different beast. (The OAC post route-proving modifications although at system level were quite extensive, these were miniscule in comparison to the differences between 202 and what we like to call 'the REAL Concorde'. Don't get me wrong, 202 did some absolutely stirring work in terms of route-proving and certification trials, and the restoration done at Brooklands is most impressive indeed, but she is and always was, nothing other than a test aircraft. She was no more a production airframe in reality than the pre-production aircraft 102, and I'm afraid that anyone thinking that she is anying other than this is truly deluding themselves my friend.
I'm sorry if this reality is dissapointing steve-de-s, but if you want to see a Concorde that is truly representative of what the aircraft was really all about I suggest that you pop up to either Manchester or East Fortune. (The only airliner museums in the UK now open to public viewing). The Manchester exhibit in particular is truly superb and beautifully kept by some great people, and shows you exactly what Concorde, THE AIRLINER was actually like, rather than just seeing a test specimin. (A superb specimin 202 indeed she was, but this is ALL she ever was, a test specimin).

Best regards
Dude :O

agreed Dude...

202 was built as 2nd Production, with a defined role as a test aircraft. Several studies were carried out over the years to see if she could be reused. Initially with the manufacturers, where if Concorde has been a success she could have been refurbished and sold to another airline at a "good" price. Of course here flying outside the certified flight envelope led to a lot of further concerns that really was curtains for any modification.

BA had robbed a lot of parts from her in the 80s, especially to bring G-BOAG back into service, so it was a no brainier in the end to put her in a hangar and rob whatever was required to kept the fleet of 7 in the air.

One little point, in the very late 70s here MEPU was decommissioned and she was fitted with the HYRAT...although the guts of the de-contaminated MEPU is still up in her tail cone.

If you want to see an Concorde as it was in Airline Service go visit MAN or EF, fantastic displays showing an Airline Concorde in the 90s or 00s

If you want to visit a Concorde and want to see the 4 stories in one (Concorde story, the unique story of a development aircraft, the airliner passenger experience and they story of how Concorde pilots were trained).... then visit Brooklands.

We've never been able to prove from a documented drawing perspective at Brooklands that the roof of the forward fuselage was any thiner than that of 204.

Well in that case you are obviously right I suppose and BA, BAe (as it was) and the CAA were all wrong as far as component 30 goes. And everything that I was told at Fairford was wrong too. I guess it goes to show I suppose that all these bodies can be wrong.
There were several semi-structural and 'heavy' system components that were robbed by BA (I removed some stuff myself in the mid 80's and early 90's), but the fact remains that there were massive system differences that could never be reconciled by simple 'mods'. The fact also remains that she was a 5100 variant aircraft and not a 5101/5102 variant (or a 100 series aircraft either) and was significantly D-I-F-F-E-R-E-N-T to the 'real' aircraft, the airliners. I was THERE and I SAW the differences myself enough times for goodness sake, and the fact remains she was NEVER an airliner and never had any real prospect of being one. (But as I said before, she was a wonderful TEST specimin and did some stirling work). Brooklands really has a lot to offer the visitor as an exhibit I suppose but if you want to see Concorde THE AIRLINER then you really need to go elsewhere. Manchester in the only place where you can now see an intact production series Concorde in the UK and as I said before is NOW lovingly cared for by some brilliant people.

Regards
Dude :O

M2dude, any chance of clarifying the "variants" (if only with a little table)?
I always thought "100" was the "bare" production aircraft definition, "101" and "102" were the AF and BA specs (equipment, cockpit, cabin), "103" being PanAm, etc. and I've never seen a mention of a "5100/5101/5102" definition.
Would be nice to get this sorted in my ancient brain...... thanks in advance!

CJ

Dude, can I join Christiaan in requesting more information on that '5000' series numbering; I have never come across it before.

Also, I have asked the CAA surveyor who was most likely to have made that reskinning decision for more data. Perhaps he can remember the problem with the forward fuselage skins. Certainly when we were standing together inside 102 last week and talking about fuselage modifications for relifing the aircraft the problem of Component 30 was not mentioned!

I'll keep you in touch.

CliveL

PS: You were going to get a lot for your £30:ok:

I think even in 1985, at the age of 14, I could have possibly scraped £30 together if you'd told me i'd get a trip in her :}

Oh you guys are so cruel. :D

Dude

I have now asked two senior CAA surveyors about this, and neither remember anything but the crown modifications that went with RELIFE. Sounds like somebody didn't want to do the conversion :hmm:

CliveL

I hate to go back several pages, but I still have a basic question about the lift generation when the AoA was more moderate.

When not generating vortex lift, was the airflow attached over both the upper and lower wing surface?

The mental picture I have is that during supersonic flight and also during subsonic but high-IAS phases, the wing was generating lift in a way Newton and Bernoulli would have immediately recognized. As the IAS decreased and AoA increased, the vortex started at the leading edge, and gradually grew in both size and contribution to overall lift until the vortex (or vortices) accounted for all the lifting force.

The simple answer is yes, it was attached flow.

The vortices never provided all the lifting force. Up to about 6 or 7 deg AoA there was no vortex lift, just the usual wing tip vortices. Above that AoA the non-linear (vortex) lift grew steadily until at stall (about 23 deg AoA) the vortex lift was around 45% of the total.

CliveL:

Was the vortex lift characteristic of the ogee wing aerodynamics fully understood before the aero configuration of Concorde was finalised?

How much did the BAC 221 (the Fairey Delta II analog of Concorde) contribute to the understanding of vortex lift of this wing?

TwoChai

twochai

I would say that it was. Remember that the design went through several phases before it was finalised and we did an awful lot of testing and tweaking of the detailed geometry to eliminate a gradual pitch-up and to increase the vortex lift at any given AoA, so by the time we defined the production aircraft wing we knew pretty well all there was to know about vortex development from the AoA at which it started right through to the AoA at which the vortices burst.

The BAC221 didn't contribute much to the details of this understanding as it was rather too late to help in prototype definition and the production development was all about the details of planform, camber and twist. But then the 221 wasn't intended to study vortex development; it was built to examine the handling characteristics of slender ogee wings at supersonic speeds.

CliveL

Interesting, as always.

Thanks.

CliveL, correct me where I'm wrong.

* Most deltas develop some vortex lift, and there were several deltas flying long before Concorde, so the phenomenon was not unknown.
Shaping the wing, and in particular the leading edge, optimised the effect on Concorde.

* The ogee (slender delta) wing was original proposed by NASA (possibly still NACA at the time) as best suited for a supersonic transport. The information was in the public domain by the time the "BAC223" and "Super Caravelle" were first revealed (they later "merged" into the Concorde design).
The Tu-144 design used the same information, which is a major reason for its resemblance to Concorde, rather than espionage...
How much the full advantages of the 'vortex lift' were understood at the time, is still an open question, IIRC.
I'll have to look for the original NASA TN (Tech Note)... it may be on the web somewhere.

* I would think the Handley Page HP115 slender-delta low-speed test aircraft must have contributed some details about vortex lift.
http://upload.wikimedia.org/wikipedi...0px-HP.115.gif
Sorry, I can't find my own photos of the beast.
It's now in the Fleet Air Arm Museum at Yeovilton (UK), together with Concorde 002 and the BAC-221.
It still has the "smoke tube" on the left wing leading edge, that was used to visualise the vortex over the wing (not yet fitted when the photo above was taken).

CJ

Dare I ask for the more complicated version?

Sidebar: in a supersonic wind tunnel test, do you get a sonic boom?

Slender wings
 

Christiaan

Quite true, and I hope I didn't give the impression that it was otherwise. On this side of the Atlantic France had the Mirage series, UK the Javelin, the two Avro aircraft and of course the FD2. However these all had relatively rounded leading edges which reduced the effect somewhat.

I must admit that I was not aware that NACA had proposed an ogee wing for supersonic transports, although all the US SST designs featured 'double deltas' . Ken Owen's book says that US firms had been working on SST research and design studies since the late 1950s, and since the UK equivalent, the Supersonic Transport Advisory Committee (STAC) ran from 1956 to 1959 and definitely included sharp-edged slender wings amongst their studies, I would say UK work was at least in parallel.

But to be frank, the basic idea sprang from German research done during WW2. They were well ahead in knowledge of the aerodynamics of delta wings as part of their research into aircraft suitable for the higher speeds that went with those new-fangled jet engines. Then, after the war's end, the German scientists migrated to either the UK and US (if they were lucky) or got carried off to Russia. They brought with them all the knowledge they had gained (and of course there were specific trained teams whose job it was to search the German research establishment records for any useful data. On the UK side certainly the idea of exploiting vortex lift for use on an SST was generated by German researchers working at the RAE (Kuchemann and Weber in particular). My guess (I don't know for sure) is that similar things happened in the US, although "their Germans" seemed to be more interested in rocketry.

Not as much as you might think, because like the 221 it was too late to have much influence and it also was built to study slender delta handling, in particular a possible problem known as 'Gray's oscillations' rather than vortex lift as such.

Clive

Not sure I know how to answer this! I will need to think on it.

I had thought I might have some pretty pictures but I haven't got anything for low AoA. I find it difficult to respond to such a general quetion though. Could you be a little more specific as to the bits that interest you?

Good question!

I THINK the answer is no. You will get the bow shock of course and this will be reflected off the tunnel walls so you must have a big tunnel or a small model to avoid these reflected waves interfering with the flow over the tail of the model, but the pressure rise on the tunnel floor is 'static' and the tunnel walls are massive steel construction. I may be wrong here, but I associate sonic booms with a rapid rise in pressure and a 'movement' of that pressure rise past the observer. In a tunnel you don't get this 'dynamic' effect (unless of course you can arrange to walk past the working section at 660 mph :ok:


CliveL

Edited after some thinking

CliveL (And ChristiaanJ)
Sure can Clive. These are the BA 5102 numbers, Air France 5101 numbers were corespondingly identical chronologically.: G-BOAC - 5102-01. G-BOAA - 5102-02. G-BOAB - 5102-03. G-BOAD - 5102-04. G-BOAE - 5102-05. Although G-BOAG (G-BFKW) and G-BOAF (G-BFKX) were originally Variant 192 (British Unsold) aircraft, these correspondingly became 5102-06 and 5102-07. I wonder if anyone here remembers G-BOAF doing her pre-delivery flying at Filton registered as G-N91AF? I remember when I was at Filton doing one of my Concorde type courses in 1980, and there was good old Foxy Lady with her 'Branniff' registration. She was re-re-registered :rolleyes: to G-BOAF prior to delivery to BA.

The Component 30 skin thickness issue was not relevant for RELIFE 2; you and I know that the major 'skin' issue here was the centre fuselage crown area. The issue of Component 30 was a 201/202 issue only. (Assuming that the French had the need/desire/capability of adding another airframe to their fleet.
And sorry everyone about the £30 cost of converting 202 into an airliner, I meant (dumb ass that I am) £30 MILLION. :\

Best regards
Dude :O

I though delat wings didn't stall provided there was sufficient power to overcome the drag (thought at ludicrously high AoA that power requirement would be ginormouse!)?

In the book The Concorder Story (5th edition) on pages 138 / 139 it talks about the crown modification with pictures of what was done. In précis it states that the crown modification was to strengthen the top of the fuselage at rotate, it states that this was a candle sticked task which required the a/c to be jacked up so the skin has zero stress. The crown modification also included an additional strap over the fuselage just to the rear of the Center door. Appologies for the précis of the text but I hope that this is of use. Oh yes the pictures of the modification are on page 140.

Dude,

Agreed on crown issue, but I am getting completely negative responses from CAA guys regarding any 201/202 differences such as you describe - nobody remembers it!

(Check your PMs)

SSD

By "Stall" in this case I meant the maximum ift we could use. There was in fact a small 'hiccup' in the lift curve against AoA, but the lift went up again afterwards. However, there was a definite nose-up 'break' in the pitching moment which we took to be the limiting AoA and regarded as a 'stall'

CliveL

May I ask you guys another question relating to the book I mentioned earlier, in the same book it shows a Concorde with a Airbus sidestick control. I wondered if anymore information is known on this modification I suspect t must have been quite an systems integration exercise.

No, I probably couldn't.

Let me ask it this way: Could a student in Aeronautical Engineering calculate the lift and drag for (non-vortex) Concorde using the same equations he would use to calculate lift and drag for say, a 777?

In other, other words... I understand that there's a very different phenomenon developing a chunk of lift at high AoA. But the wing still has a very unique shape and camber, so I wonder if-- when the AoA is *not* as high-- phenomena responsible for our 777 staying up fully apply to Concorde.

If I'm just missing the boat completely here, just give me the stern eye and ask me to reread some physics.