Posts about: "Radiation Exposure" [Posts: 13 Page: 1 of 1]¶

I rode Concorde two or three times and what a ride it was!

On one occasion I had booked to travel BA 'J' class from Washington to Delhi on a regular business trip. Out of DCA to JFK they booked me on the 'Concorde shuttle' (a Dash 8 of US Airways, believe it or not) to connect with a 744 to LHR and another connection on to Delhi. At DCA check in the agent mumbled something about a catering problem out of JFK, but I took no particular notice. On arrival at Kennedy an agent with a name placard diverted me to the Concorde gate, a nice surprise indeed, even for a BA Gold Card holder.

On boarding Concorde, I gave my business card to the purser, asking that she pass it forward. A few minutes later as the door was closing she came back to pass along an invitation from the skipper to join them in the cockpit. During the short delay for start clearance, the captain briefed me on the Canarsie 31L departure I was about to watch from the jump seat behind. "3-2-1 GO" as the aircraft lept forward, V1/Vr/V2, 100', roll left 30 degrees to track towards Canarsie, 1' 30" (or something similar, some details are long forgotten now) power back for 500'/minute ROC to 3,000', then accelerate to 250K as the heading continued around for the outbound course and the ocean crossing. A true aerial ballet.

For the balance of the climb I plied the guys with questions and received courteous and detailed answers to every one, along with a 'freebie' - some hilarious repartee between the BALPA captain and the management F/O type, with occasional interjections by the Engineer. I stayed through the supersonic acceleration until I thought I'd worn out my welcome at cruise climb, returning to my seat in the mid cabin area for lunch. They invited me back for the descent and approach, which was very well appreciated.

On descent over the U.K. and passing through 10K' abeam Southampton, as I remember it we got a yellow 'Radiation' caution light (normally to warn of higher than normal levels of radiation in the tropoause from sun spot activity, I believe), which caused me to ask WTHWT? The slightly bored F/O said, as he cancelled the light, "Oh, its 'just' a nuclear power plant down there, we get this all the time"! (And for all these years I had swallowed the PR line from the nuclear industry that they were squeaky clean, unlike those of us in the aircraft manufacturing business??)

The approach and landing at LHR was fascinating to watch, without the frenetic activity of the departure. No flaps and no configuration change after gear down, virtually no flare, perhaps even a little nose down pitch as I observed (was that true??) the handling pilot just let it float into ground effect for a gentle touch down, snappily into reverse and heavy, but not maximum braking. It looked easy, of course.

The F/E was a key part of the entire operation and I find it hard to believe that a Concorde "B" would have eliminated his position, no matter how automated the systems might have become. The whole flight was very, very professionally handled with that air of apparent casualness that comes only from a very disciplined team operating at the peak of performance. A true joy to watch.

I guess I was just a minor part of the vaunted 'halo' effect that BA marketing always claimed for Concorde - its ability to pull additional traffic to its worldwide services in a very competitive business climate. But it sure worked for me! And all because of a catering misadventure, or was that just an excuse??

However, the thing that has always truly amazed me about Concorde is that this machine was created by two companies, two countries, with two languages, two systems of measure and two very different cultures in a period before the invention of Computer Aided Design and on-line communications! What a marvellous thing that mankind created. My hat off to you all.

Thank you, John, that was some flight!

TC

twochai
It is wonderful that you have such fond flying memories of Concorde;in the pre-911 days there was a fairly liberal open door policy for flight deck visits (Although all passengers were made to feel really special, it is so great that the guys had you up front for so long on that flight. You just never lose those sort of memories, I know).
The Radiation Meter was an interesting addition to Concorde's collection of avionics kit. It was primarily designed to detect solar proton, as well as neutron radiation, (the detector element lived behind the fwd r/h wardrobe as I remember and was a total pain in the 'you know where' to get at). The indicator displayed the dose rate in millirems/hour, with amber and red triggers, triggering a master alarm. (The amber was a mere caution, whereas the red was a warning. I can't quite remember any figures, but a descent was required with a genuine red warning. I think I'm correct in saying that no such descent was ever required, at least in the UK). There was a huge amount of concern initially about crews long term exposure to radiation, after all there is a fairly linear relationship between solar radiation and altitude. In reality however Concorde crews received far less radiation than subsonic crews; although the dose rates may have been higher, the sector times were a fraction of a lot of the subsonic routes. (Even a subsonic LHR-JFK is WELL over twice the sector length). Nuisance ambers were not uncommon, a certain 'facility' in Berkshire would often register as the aircraft over-flew, as well as MANY years ago, Three Mile Island itself. I remember that there were long term plans to replace the radiation meter with a portable 'carry on' device that was being trialled. (Spares for the detector were becoming very difficult to obtain).

Dude

All this talk of a 'B' model is both interesting and a bit frustrating. It must be all the more so for our main contributors - M2Dude and ChristiaanJ - and I guess the crews themselves, that the 'B' never saw the light of day. The discussion about the engines/ intakes/ nozzles is taking place about another flight level above my head but still riveting stuff nonetheless.

May I ask a question about another aspect of Concorde life? In my own job as a CT/MRI scanner engineer, I was for many years a 'Registered Radiation Worker' and indeed I still wear the equivalent of a film badge. My annual dose though was and is tiny, virtually background. However, I remember seeing a chart from the Radiological Protection Board some years ago, that seemed to suggest Concorde Crews had the highest radiation dose in any industry routine operations.

Was this true and did Concorde crews wear a film badge as I did? I understand that 'ordinary' flight crews get quite a radiation dose, but nothing like the 60,000ft doses the lady permitted?

Roger.

Good question Roger, the short answer to that is 'no they didn't. Radiation (in millirems) was logged after each flight, the data coming from the onboard radiation meter developed at the Harwell nuclear research centre in Essex. (A counter clocked the overall dose and an analog dial indication showed the dose rate). Although the dose rates in Concorde were higher than in a subsonic aircraft, because the sector times were over twice as short everything kind of cancelled out. The indicator itself
I do remember that when the Three Mile Island Pa accident happened in 1979, some spikes were seen on the radiation meter on the IAD-LHR sector, and occasionally throughout the years we got minor spikes when overflying the Atomic Weapons establishment at Burghfield in Berkshire. (All we did in that case was to telephone the duty officer at Burghfield who would say 'thank you' and log the event).

As far as the 'B' model goes, well yes it is a little frustrating to know that the full potential of this wonderful design was never fully realised, but as I said before, 'the 'A' model itself was still totally amazing.

Dude

Out of pure curiosity... any chance of finding that chart still?
Did it refer to dose rate or accumulated dose?
As M2dude already said, the dose rate was roughly twice that for a subsonic crew, but because of the shorter flight duration, the accumulated dose was no different from the large majority of crews in general.

CJ

As an ATCO we had very specific instructions about how to deal with a Concord(e) radiation overdose. We were told that it would have to make an emergency descent and how to integrate it with other traffic as it descended and what the priorities were.

Has any Concord crew ever had to do this?

I dealt extensively with the London sector (S23) most likely to be involved in this procedure but fortunately it never happened to me.

Dave

Dave ,
I was looking to confirm my own memory on the matter and found this quote, from a personal friend, on another aviation forum. Knowing him, and knowing where he worked, I would trust that statement implicitly!
The "blips" on the radiation meter over certain "hot spots", in the UK, the US and the Middle East, are well-known bits of Concorde folklore.

CJ

arearadar

...As an ATCO we had very specific instructions about how to deal with a Concord(e) radiation overdose. We were told that it would have to make an emergency descent and how to integrate it with other traffic as it descended and what the priorities were...

The display, on the radiation meter, was divided into three, coloured, sections.
If the "Red" level on the radiation meter was reached, this would also trigger the central M aster W arning S ystem to display a Red MWS RADN light, and also to sound the MWS gong.


The procedure to be followed was simply an Abnormal Procedure rather than an Emergency Drill .
So, even with an instantaneous radiation level in excess of 50 millrems/hour indicating, this was not thought to justify the risk of an emergency, uncleared, descent through flights levels possibly occupied by underflying aircraft, and, in fact, if the warning remained RED below 47,000 ft, the warning was deemed suspect, and the descent could be stopped.

It was of some concern that the sort of radiation levels that would trigger the radiation alarm might very well also be playing havoc with radio communications, particularly HF communications. The possibility of being unable to communicate with ATC was one that had to be considered, and so it was only under these circumstances, with both a Red MWS RADN warning and an ATC communications failure, that the Captain was permitted, at his discretion, to perform an uncleared descent.

It's comforting to know that you were prepared to deal with us if required, but unlikely, I would have thought, that your services would have been called upon in practice.


...Has any Concord crew ever had to do this?...

I not aware of any such descent incident, although obviously I can\x92t state definitely that one never occurred.

It wasn't unknown for the radiation alarm to go off, I\x92ve had it, briefly, twice, both times at lowish level over the sea on departure from JFK. On one occasion there was nothing at all to indicate what might have caused it, on the other, we had just overflown a rather large waste barge being towed somewhere!


Best Regards

Bellerophon

Dave ,
From all the disparate reports I've seen over the years from "usually reliable sources", it does seem indeed nobody ever experienced it.
The suspicious "blips" on the indicator over "suspicious sites" were never long enough to initiate an emergency descent.
And that radiation always came from below, not from outer space....

CJ

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

hissinsid
I have to admit, this is one superb image (and a nice high resolution one also) of my old friend Alpha Alpha.

As far as the trip switches to the rear of the captain, not quite sure what you are refering to I'm afraid unless you mean the area on 213 circuit breaker panels? Also located here are the Audio Selector Panel, the emergency windshield de-ice switches (quite hairy really , 200 volts placed straight on the main windshield heating film with no temperature regulation or overheat protection). As well we also have the lighting controls for the panel and a fully deployed observer's coffee cup holder.
As far as the bits either side of the E/O's table, well there is a fair bit, but I'll do my best:
To the left we have the engine start panel, the air conditioning test panel (also encompassing the fuel vent suppression test and indication and gauge limit reset button) and door warning panel. Below these panels are the mode selector panels for the Inertial Navigation Systems and the artificial feel test and Ram Air Turbine control panels. At the very bottom we have the air intake test and diagnostic panels, as well as the anti ice indicator panel. The E/O's Audio Selector Panel and last of all we have the radiation meter and landing gear fault annunciator. (This item is not fitted to aircraft G-BOAG or any Air France aircraft).
To the right we have the Aircraft Integrated Data System panel and immediately below that the compass control panel. (Concorde was one of the very last aircraft to have a magnetic heading reference system, modern aircraft synthesise magnetic heading against true heading and geographic position). Below that we have the oxygen indication panel and to the top right of the section we have the engine and fire test panel. Immediately below this we have the automatic test panel for Automatic Flight Control System and below this the smoke detector test panel. Below this we have the cockpit voice recorder panel and last of all the current monitor panel for the intake secondary air doors.
WHEW!! I hope this helps but if not please ask away.

Regards
Dude

After about a week of 3-hour nights (not much on the telly) I have finally got to the end of this thread. Let me echo others in praising the patience and technical openness of the main engineering contributors, along with the excellent recollections of the pilots, cabin staff and many others.

I am afraid I have only been on Concorde around a dozen times, and as I live a few miles from Duxford, you'll probably guess that's 101 now in Hangar 1. Standing in the cabin I can only imagine the experience of actually flying in her, but you guys have certainly bought her back to life in my mind at least.

While reading the thread I came up with many questions (around ten or so) and these have been answered in later exchanges on the thread, however I do have a few left over:

1. The speed freak in me always wants to know "how fast"? Notwithstanding the principles outlined on p.55 by CliveL and M2Dude, if the intake system were somehow made "more leaky" and reheat were applied, in theory at least, how much more thrust could the 4 engines produce, in "ideal" conditions (I saw somewhere that -80C had been encountered)? If you then extrapolate the drag, what sort of peak Mach number might be attainable in short bursts (ignoring for now the detrimental effect on the airframe?)

2. There was a discussion or two of the (highly theoretical, expensive and unlikely) prospect of restoring one of the airframes back to flight around p22. However I don't think I saw 101 or 102 mentioned in any of these discussions, are these even further 'gone' (101 having sat outside for 20 years)? On the other hand, would the lack of sponge-like insulation mean less corrosion might have set in?

3. Again on p.55 there is mention of (naff) paint schemes and their bad effect on skin temperature. Was the paint on Concorde specifically chosen to radiate infrared (for example) to help cooling? The SR-71 (which I also visit at Duxford regularly - how lucky am I!) of course is matt black, which presumably radiates even better? When the airframe attained thermal equilibrium at the top of the cruise, what were the relative contributions to cooling of: radiation, cold uncompressed air passing over parts of the skin, the internal aircon (cooling from the inside), etc?

4. M2Dude referred a couple of times to robbing spares from other airframes. Spares that may have been 5-8 years old? What sort of testing regime must these spare parts go through to ensure they are still fit for flight? Is it labour-intensive?


If I can opine (at the risk of having M2Dude chastise me if he still reads this - as I am not staff) the computer he mentioned on page 37 sounds to me very much like a "bit slice" computer. These were typically constructed from discrete logic and quite often had very long words - 64 or 128 bits. I only ever saw one of these in my 30-year career in computing, a rare beast indeed. And yes I remember that Mil Spec TTL - back in the day I used to pop the lid off the ceramic packages and you can look at the gates, and even watch the silicon glow if you apply a bit too much Vcc! But I digress.

Thanks again for a fascinating thread.

This extract from Norman Harpur’s 1966 paper on “The Structure of the Concorde” explains it pretty well I think. Norman was the chief structures engineer on the British side so he can be classed as someone with definitive knowledge.
“At Mach numbers of about 2 it pays to paint the external surface white. Despite what the textbooks say, a white surface can be made almost as good as a black surface at radiating heat away from itself whereas it is much better than a black surface in reflecting solar radiation. Under these circumstances, at these speeds, a white surface will result in a cooling of something like 10 deg C. If we increase the speed of the aircraft, up to say a Mach number of 3, far more heat is transmitted by skin friction and the effect of solar radiation is relatively small. In these conditions it now becomes important to have the highest possible emissivity on the surface to reduce the heat as much as possible and here, even though relatively small, the gain between white paint and black paint is important. Therefore the Mach3 supersonic transport should really be painted black.