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streamdreams
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Did Concorde Ever Depressurize?

Mon Aug 22, 2005 4:41 pm

With all the recent discussion on depressurization, particularly with reference to Greek tragedy (god bless all) , I wondered what the story would be for Concord at mach 2 and FL600 ( I think, feel free to correct me.)

Did it ever happen ?
Where the procedures any different , what were they ?
 
FlySSC
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Did Concorde Ever Depressurize?

Mon Aug 22, 2005 10:11 pm

As far as I know, it never happened to Concorde.
At least at Mach 2.00/60.000 ft ....
 
EMBQA
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Did Concorde Ever Depressurize?

Mon Aug 22, 2005 11:47 pm

Where the procedures any different, what were they ?

If it had ever happened at cruise altitude they would have all died instantly. Depressurizing at 60K is a WHOLE lot different then at 30K.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
luisca
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Did Concorde Ever Depressurize?

Mon Aug 22, 2005 11:54 pm

At 60K feet a rapid decompression would cause the blood to literally BOIL, becouse of the reduced vapor pressure, water evaporates before it frezzes,even at -50C.
If it ain't Boeing (or Embraer ;-)) I ain't Going!
 
cedarjet
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Did Concorde Ever Depressurize?

Mon Aug 22, 2005 11:59 pm

All true. I don't even think Conc had O2 masks in the cabin. Maybe it did, in case something happened during climb or descent; but if something had gone wrong at cruise altitude, it would have all been over for Joan Collins, Kate Moss et al pretty damn quick.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
777236ER
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 12:09 am

Quoting Cedarjet (Reply 4):
All true. I don't even think Conc had O2 masks in the cabin. Maybe it did, in case something happened during climb or descent; but if something had gone wrong at cruise altitude, it would have all been over for Joan Collins, Kate Moss et al pretty damn quick.

Of course Concorde had oxygen masks! The prototypes had larger 707-sized windows, but these were deemed to large as the cabin depressurised too quickly were one to rupture. Hence the smaller ones seen on the pre and production models. This was done mainly to give passengers and crew a greater time of useful conciousness, so they could get their masks on.

Your blood only begins to boil at 63000ft ISA. You'll instantly lose conciousness at 50,000ft ISA without supplemental oxygen. Hence small windows and excess air supply from the bleeds. The aim was to never let the cabin altitude get that high.

[Edited 2005-08-22 17:28:27]
Your bone's got a little machine
 
vc10
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 12:45 am

Concorde ---- had conventional oxygen masks for passengers and cabin crew whilst the flight deck crew each had a full pressure breathing system.

If there was a de- pressurization then the drill was the same as any other aircraft in that everyone went on oxygen and the aircraft was descended to safe altitudes which would allow the majority to dispense with oxygen.

Now the difference being that Concorde had a lot more height to loose and also it had a lot of speed to dispense with but otherwise just the same.

Everybody talks of the cabin going rapidly to 60,000ft but that was never really the incident imagined for a depressurization, more the cabin coming up quickly with an emergency descent being commenced as the cabin height climbed through approximately 12,000 ft so the descending aircraft would meet the rising cabin somewhere between 20 and 40,000 ft.

Even the loss of 2 cabin windows could be contained by the discharge valves closing,and loads of safety measures to prevent the pressurization running away to a dangerous position. Now I hear you all saying what about if you had a structural failure at altitude, well I think if you did have a major structural failure causing an explosive decompression at Mach 2.0 and 60,000ft the aircraft would have probably come apart but assuming this did not happen then the flight deck crew on pressure breathing should have, at least in theory, been able to get the aircraft down to a safe height which would allow the passengers to recover.

No, Concorde never did have a real depressurization but on test flights the cabin was allowed to climb up to 20,000 ft so as to check all the passenger oxygen system worked OK
 
FlySSC
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 12:48 am

Quoting Cedarjet (Reply 4):
I don't even think Conc had O2 masks in the cabin

Of course Concorde had 0xygen masks !
You can clearly see the PSU containing the Oxygen masks above the seats on this picture :

View Large View Medium
Click here for bigger photo!

Photo © Peter Unmuth - VAP



The row 1 and 14 (1st row in the second cabin) had a block of 3 masks on each side.
In the rest or the cabin, rows had alternatively blocks of 2 or 3 masks on each side.
There was also a "manual" command to open the emergency oxygen supply on a panel located above the Door 3Right.
 
David L
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 1:45 am

Quoting VC10 (Reply 6):
I think if you did have a major structural failure causing an explosive decompression at Mach 2.0 and 60,000ft the aircraft would have probably come apart

OK, I'm not going to stamp my foot if everyone disagrees, but it's my understanding that "Mach 2 at 60,000 ft" isn't as bad as it sounds. Isn't the IAS the crucial factor in determining how much "ripping apart" force the air exerts? Wasn't the IAS in the region of 350-400 knots? Still higher than a normal aircraft would have to endure but not, as I'm guessing, quite as bad as it sounds. Of course, there's the distinct possibility that's all bollocks.

No doubt GDB and/or Bellerophon will set the record straight.
 
David L
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 2:23 am

Ah, VC10, I thought you were saying Concorde was more likely to be ripped apart after structural damage than other types. But, on reflection, I guess you're saying that the smaller windows and pressurisation system would have coped until the aircraft descended but, if the explosive decompression was so violent that it couldn't cope, it would probably be because there had been major structural damage. Sorry about that.  

The bottom line is, therefore, that Concorde was designed to cope provided the damage wasn't so violent that the aircraft had started breaking up and depressurisation no longer mattered anyway, right?

[Edited 2005-08-22 19:25:12]
 
GDB
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 2:46 am

As stated, the aircraft and it's systems were designed to cope with a cabin pressure failure at altitude, otherwise it would never have been certified.

63,000ft is where liquids would boil, Concorde in pax service flew at a max of 60,000ft, briefly during BGI sectors, 58,000 was far more usual
(I only got to 60,000ft once, on a BGI, the last ever one for G-BOAE's retirement).
Though you might reach around 63,000ft on a zoom climb, on a C of A air-test.

At Mach 2 IAS would be around 500kts, TAS being around 1350.
My understanding that the system/contingencies were for the highly unlikely event of a double window failure.
You suffer a major stuctural event at Mach 2 then it's all over anyway, hence the design of the aircraft, to provide as safe a pax transport at Mach 2, as all the rest have to do at Mach 0.85.
The aircraft did have the longest certification programme in airline history.
 
cloudyapple
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 3:09 am

Quoting 777236ER (Reply 5):
The prototypes had larger 707-sized windows

It must be the world's largest aircraft ever! Big grin
A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
 
David L
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 3:12 am

I didn't realise the IAS was as high as that. The reason I felt obliged to comment was that I recently had a conversation with someone who got very worked up about the thought of "Them" sending members of the public through the sky at speeds that caused "unimaginable stresses" on the airframe, something only military pilots should have to endure - completely reckless and highly dangerous, apparently!
 
Kay
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 3:38 am

It's all these facts that make the successful ejection of a Russian pilot at 62,000ft so sensational.

I forgot who, but it was during the cold war. A pilot ejected his aircraft at 62,000ft and managed to survive. The article is dug somewhere in my magazines. I'm not finding it on google.

Unbelievable but true! They couldn't mention this world record until well after the cold war over.

Kay
 
GDB
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 3:45 am

Amazing isn't it? David L, the basic technical illiteracy of so many people.
Along with a total absence of common sense, I blame the media.

'Stresses' indeed! Let's see, above most turbulence, a lower cabin pressure, shorter time stuck in an aluminum tube in the first place.

The stresses were very 'imagined' hence the massive development and certification effort, did anyone say the same when we moved from props to jets?

The smoothest flights I ever had were on Concorde.
 
Bellerophon
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 9:24 am

Streamdreams

... I wondered what the story would be for Concord at mach 2 and FL600...

In the event of a total and near-instantaneous decompression to 60,000 ft, then the ramifications would have been very serious. Passengers exposed to atmospheric pressure at FL600 for any appreciable length of time would have had only a few seconds of consciousness followed by a merciful lapse into unconsciousness.

In addition, the sort of damage or failures necessary to have caused this would have brought with it a whole host of other problems, not the least of which may have been that the aircraft had ceased to be a viable flying machine - the early Comet accidents being a case in point.

However, in the overwhelming majority of decompressions, experienced over many years on all aircraft types, the aircraft did not explosively depressurise to ambient atmospheric pressure, even if it may have felt like it to the occupants.

Whether due to pressurisation system failure, discharge valve failure, a small hull breach, a door or window blow-out, or just plain human error, the cabin took time to decompress, often a considerable amount of time.

It is this time, the time the cabin takes to climb which provides the flight crew with a safety margin, precious seconds in which to act to protect passengers and crew from extreme cabin altitudes.

On Concorde, this involved the crew in protecting themselves (pressurised O2 masks) analysing the situation (what warnings?, what cabin rate-of-climb?) rectifying if possible (re-instating packs, selecting alternate systems, closing errant valves manually) or, if control of the cabin had been irretrievably lost, initiating an emergency descent.

The cabin altitude on Concorde was typically around 5,000 ft in the cruise, and in common with most commercial aircraft, various flight deck warnings would occur as the cabin altitude rose through 10,000 ft, and again passing through 14,000 ft, to alert the crew to any problem, assuming their own eyes, ears, sinuses and lower intestines had not already done so!

There were also many protection devices fitted to Concorde to ensure that the cabin altitude never exceeded 14,000 ft, however, even had they all failed and the cabin had been climbing at 5,000 fpm, it would still have taken 36 seconds before the cabin altitude exceeded 8,000 ft.

It would have taken 108 seconds before it exceeded 14,000 ft and around 3 minutes for the cabin to exceed 20,000 ft, by which time the aircraft would have been well on its way down to safety in an emergency descent.

In most cases, the cabin altitude would never have got above 20,000 ft, and the overwhelming majority of these incidents, though alarming, would have been highly survivable for all occupants. The chances of passengers ever being exposed to atmospheric pressure at FL600 was an extremely remote possibility


...Did it ever happen ?...

It never even came close to happening, during 27 years of commercial service.


...Where the procedures any different , what were they ?...

Starting from FL600, the initial rate of descent would have been around 12,000 - 15,000 fpm, reducing on passing through FL500 and increasing again on passing through FL400.

On Concorde, once below FL500 an emergency descent also became a deceleration manoeuvre, which brought with it the necessity to move fuel forward rapidly to keep the CG within limits as the aircraft Mach number decreased.

Various emergency descent profiles were tried during test flying. The one that was finally adopted for line operations gave an average rate of descent of around 7,000 fpm, and kept the CG within limits throughout.


Luisca

Dr Harry Armstrong did a lot of pioneeering work into aircraft pressurisation at Wright Field, in the USA, in the late 1930’s.

It was there he discovered, amongst other things, that at 63,000 feet pressure altitude, blood will boil at body temperature, an altitude limit know to this day as the Armstrong Line.

If you would like to read about Dr Armstrong click here


David L

...Wasn't the IAS in the region of 350-400 knots?...

The IAS at FL600 and M2.0 was around 430 knots IAS.


Best Regards to all

Bellerophon
 
B2707SST
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 9:31 am

The Boeing 2707's maximum certified altitude was to have been 73,000 feet at Mach 2.7. The air conditioning system was designed to keep the cabin pressure altitude under 14,000 feet with a 42 square inch hole in the fuselage (windows measured 28 square inches).

The emergency descent schedule could take the aircraft from 73,000 feet to a safe cruising altitude of 14,000 feet in under seven minutes. Using idle engines and 45 degrees of speedbrakes all the way down, horizontal decelerations of up to 0.5g and descent rates exceeding 10,000 ft/min would have been encountered at normal weights. That would have been quite a ride!

--B2707SST

[Edited 2005-08-23 02:58:35]
Keynes is dead and we are living in his long run.
 
SFORunner
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 11:05 am

I think Captain Patroni would disagree with all of us!







 
eg777er
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 11:28 am

Now, Bellerophon, you've written that somewhere before...haven't you?  Wink

With regard to the technical illiteracy of some people who think that flying on Concorde was inherently unsafe, they have probably taken their information from the USS Intrepid Museum who continually advertise in their Time Out NY listing "see the Concorde cockpit where brave pilots broke the sound barrier!"

Grrrr  Sad.
 
BEG2IAH
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 1:41 pm

Quoting Kay (Reply 15):
A pilot ejected his aircraft at 62,000ft and managed to survive.

He must have had a (full) pressure suit. Fighter jet pilots don't fly those planes in their jeans.  Smile

BEG2IAH
Flying at the cruising altitude is (mostly) boring. I wish all flights were nothing but endless take offs and landings every 10 minutes or so.
 
777236ER
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 4:51 pm

Quoting Luisca (Reply 3):
At 60K feet a rapid decompression would cause the blood to literally BOIL, becouse of the reduced vapor pressure, water evaporates before it frezzes,even at -50C.

For some reason my post was deleted, because the 'reference post was deleted'? It wasn't...

Anyway:

At 60000ft (18288m) ISA static pressure is 7172 Pa. Now the vapour pressure of blood (which is mainly water, so we'll use water) is 47mmHG = 6266.15Pa at 37C. Oh dear, that's significantly less than 7172 Pa, which is the static pressure at 60,000ft, isn't it? In fact, the altitude at which this pressure is reached (and your blood will boil), is 62958.5 ft ~ 63000ft.
Your bone's got a little machine
 
David L
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 8:44 pm

Quoting Bellerophon (Reply 15):
The IAS at FL600 and M2.0 was around 430 knots IAS.

Thanks for that.

Quoting GDB (Reply 14):
'Stresses' indeed! Let's see, above most turbulence, a lower cabin pressure, shorter time stuck in an aluminum tube in the first place.

The reasoning was that it flying twice as fast through the air as other types but there was no grasp of the fact that the air is much thinner up there.

Quoting GDB (Reply 14):
The smoothest flights I ever had were on Concorde.

I did once experience some very mild buffet for about 20 minutes quite near the top of the climb. No-one else batted an eyelid as it was nothing like that experienced on subsonic flights but there was I, sitting there thinking "hey, that's not supposed to happen up here - I want my money back".  Smile
 
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vzlet
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 10:07 pm

Quoting Kay (Reply 13):
It's all these facts that make the successful ejection of a Russian pilot at 62,000ft so sensational.

There's a recent article in the AWST "Contrails" section by a pilot who survived a breakup of his SR-71 at Mach 3.18 and 78,000 feet. He credited his pressure suit (and its oxygen supply) for his amazing survival:

"That the suit could withstand forces sufficient to disintegrate an airplane and shred heavy nylon seat belts, yet leave me with only a few bruises and minor whiplash was impressive. I truly appreciated having my own little escape capsule."
"That's so stupid! If they're so secret, why are they out where everyone can see them?" - my kid
 
cedarjet
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 10:33 pm

OK OK, so it has O2 masks. I have flown on Concorde, don't you know. I was actually thinking of the BAC111, which DEFINITELY didn't have O2 masks, except maybe the ones built for AA.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
777236ER
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RE: Did Concorde Ever Depressurize?

Tue Aug 23, 2005 11:20 pm

Quoting Cedarjet (Reply 23):
I was actually thinking of the BAC111, which DEFINITELY didn't have O2 masks

No it didn't, it wasn't a regulation at the time it was certified. That being said, I'm not sure Concorde has even been mistaken for a BAC 1-11 before...  Wink
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