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Concorde Trivia?  
User currently offlineSilverfox From United Kingdom, joined Mar 2001, 1058 posts, RR: 0
Posted (11 years 6 months 6 days 2 hours ago) and read 2125 times:

Given the assumption that there are no restrictions, how soon after take off could Concorde be supersonic, and is there a correlation between the footprint of the shockwave,with height/speed?

Thanks

25 replies: All unread, showing first 25:
 
User currently offlineXXXX10 From United Kingdom, joined Jan 2000, 777 posts, RR: 0
Reply 1, posted (11 years 6 months 5 days 23 hours ago) and read 2084 times:

I believe that it could be as little as 20 mins to M2.00 out of London its normally araound 20 mins to M1.00 and 30 mins M2.00

User currently offlineFritzi From United Arab Emirates, joined Jun 2001, 2762 posts, RR: 2
Reply 2, posted (11 years 6 months 5 days 21 hours ago) and read 2056 times:

Here comes my guess

If it were light (30k kg fuel), if it were to pass Mach 1.0 at 31,000 ft, take off at sea level with a VS of 5000 (or more if possible)to FL 310 using full afterburners during the whole ascent, it would be able to make it in 6 min, 12 sec. She would have to takeoff close to the coast then to eliminate the need for sonic boom restrictions (Shannon would be a good place).


User currently offlineXXXX10 From United Kingdom, joined Jan 2000, 777 posts, RR: 0
Reply 3, posted (11 years 6 months 5 days 21 hours ago) and read 2041 times:

I presume you mean 30,000 kg of fuel.

It may be 6 mins to Mach 1 but would probably be another 10 mins to M2, also they have to transfer fuel into the aft trim tank, this may delay them.

Just my $0.02


User currently offlineFritzi From United Arab Emirates, joined Jun 2001, 2762 posts, RR: 2
Reply 4, posted (11 years 6 months 5 days 21 hours ago) and read 2035 times:

XXXX10,

yes, I meant 30,000 kg of fuel.

I forgot about trying to calculate the time for mach 2. And yes, transferring the fuel would probably delay the procedure.



Where is GDB and Bellerophon???


User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 5, posted (11 years 6 months 5 days 10 hours ago) and read 1990 times:

Fritzi

You seem to be doing just fine without me, as some reasonably accurate estimates, along with a couple of good points have already been made.

My estimate is that with a light aircraft, it would be around 10 minutes to M1.0, and a total of 28-30 minutes to M2.0.

If I may just correct a couple of minor misconceptions, firstly the minimum fuel load for a supersonic sector is 35,000 kg, and secondly the re-heats cannot be used continuously during the climb. They must be switched off shortly after take-off, as not only are there strict time limits on their use, but also the fuel used would be far too great.

A light Concorde, taking-off on a short charter flight from an airfield near a coast, flying out to sea and not subject to any ATC restrictions, would re-select re-heats back on whilst passing through 27,000 ft and become supersonic passing through 30,000 ft after about 10 minutes.

Another 6 minutes to get to M1.7 and 43,000 ft, when the re-heats will go off, and then the main engines will take somewhere around another 12-15 minutes to get the aircraft to 50,000 ft and M2.0, depending on the outside air temperatures.


XXXX10

A very good point. The time taken to transfer fuel rearwards during the acceleration is always an important factor, particularly with a light aircraft, and is always monitored carefully. The F/E however, knows what is coming on such flights, and will start to transfer fuel rearwards a bit earlier than normal.

Provided the flight does not climb into colder-than-expected air during this phase, the fuel transfer should not delay the climb. If the flight does run into very cold air, then two of the re-heats will be turned off early, to reduce the rate of climb and acceleration.

Regards

Bellerophon


User currently offlineCptkrell From United States of America, joined Sep 2001, 3220 posts, RR: 12
Reply 6, posted (11 years 6 months 5 days 9 hours ago) and read 1973 times:

Dear Bellerophon; yet further insight to the great and complex workings of Concorde. Thank you! I always (incorrectly) assumed that re-heat was used from takeoff to supersonic. Other than high rate of fuel burn, would I correctly surmise that "re-staging" the afterburners is a temperature control requirement for the powerplants? Are the re-heats "gradually" throttled up to get to speed so there is little or no perception to the pax? I was lucky enough to fly Concorde on a demo flight out of Oshkosh years back, but I was so excited about the experience, I simply cannot remember all of the details. Thanks again...Jack


all best; jack
User currently offlineLiamksa From Australia, joined Oct 2001, 308 posts, RR: 0
Reply 7, posted (11 years 6 months 5 days 8 hours ago) and read 1967 times:

My estimate is that with a light aircraft, it would be around 10 minutes to M1.0, and a total of 28-30 minutes to M2.0.

HAHA - when i first read this i was picturing a C172 going M1.0!  Big grin


User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 8, posted (11 years 6 months 4 days 13 hours ago) and read 1894 times:

Cptkrell

…would I correctly surmise that "re-staging" the afterburners is a temperature control requirement for the powerplants?...

Yes, with the engines at take-off power, the use of re-heat will obviously cause a rise in Exhaust Gas Temperature. The EGT limit increases by nearly 100°C to accommodate this rise, but for a maximum of 2½ minutes only.

…Are the re-heats "gradually" throttled up to get to speed so there is little or no perception to the pax?...

No, there is no way to accelerate the re-heats gently up to full power, they are either ON or OFF.

On take-off, all four are selected ON together, but their use is masked by the main engines which are also spooling up rapidly, and they will not be detected by passengers.

Once cleared for supersonic flight, in order to provide some additional thrust to help Concorde through the high drag transonic region, they are selected back ON at Mach 0.95, and now their use can be noticed, as they cause a slight nudge in the back of the seat as they light up.

They are selected ON in pairs, rather than all four together, to reduce one larger nudge to two smaller ones, and in case there are any nervous flyers on board, it is normal practice for the Captain to make a brief PA, just prior to selecting re-heats, to explain what is about to happen.

Regards

Bellerophon


User currently offlineMegatop From Denmark, joined May 1999, 349 posts, RR: 0
Reply 9, posted (11 years 6 months 3 days 23 hours ago) and read 1839 times:

On a promotion flight in 1988 in Aalborg, Denmark, I was lucky to get a ride on a AF concorde.

7 min after takeoff we broke M1, and after only 12 min we hit M2.

What a ride. Sad to see those "superbirds" on pension.


Megatop


User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 10, posted (11 years 6 months 3 days 22 hours ago) and read 1829 times:

Megatop

With respect, I think your memory may have faded just a little in the 15 years since your trip, with regard to the times you give!

...7 min after takeoff we broke M1...

7 minutes (accurately timed) from take-off to M1.0 is around two to three minutes too fast, even under the most favourable circumstances.

...and after only 12 min we hit M2...

5 minutes, from Mach 1.0 to M2.0, is impossible.

An explanation of what Concorde can achieve, along with some reasons, has already been given earlier in this thread.

I’m sorry to cast doubt on your figures, but pleased you enjoyed your trip, and as you say, it’s sad to see the superbirds going.

Regards

Bellerophon


User currently offlineMegatop From Denmark, joined May 1999, 349 posts, RR: 0
Reply 11, posted (11 years 6 months 3 days 22 hours ago) and read 1815 times:

Bellerophon !

Thanks for you reply. BUT the data is correct. Remember that the flight was only for 1h10min, so the plane was rather light.

It is not my memory that is wrong. I wrote every data from that flight down in a sort of dairy.



Megatop



User currently offlineSaintsman From United Kingdom, joined Mar 2002, 2065 posts, RR: 2
Reply 12, posted (11 years 6 months 3 days 21 hours ago) and read 1815 times:

As we are talking Concorde trivia. The pilots can fly something else, so what will happen to the Flight Engineers when Concorde retires? Do BA still use them on other aircraft?

User currently offlineGDB From United Kingdom, joined May 2001, 13256 posts, RR: 77
Reply 13, posted (11 years 6 months 3 days 20 hours ago) and read 1799 times:

There are not many left, my understanding is that BA will offer them 'a package'.
In other words, 'here's some money, goodbye.'



User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 14, posted (11 years 6 months 3 days 14 hours ago) and read 1762 times:

Megatop

When posting my reply to you, I was aware you meant a light weight flight, not a flight at trans-atlantic weight, and I am also aware of how Concorde performs at light weight.

For instance, one of the many points I considered in producing my original reply, which also assumed a light weight flight, was that at light weight, the maximum subsonic climb speed is reduced and the altitude Concorde must attain before going supersonic is increased.

I have flown many such light weight flights, and I still consider the time you quote to M1.0 to be too short, and the time you quote from M1.0 to M2.0 to be impossible.

My estimates of the shortest times possible are posted above, and I stand by them.

I truly hope your flight was both memorable and enjoyable, and so, rather than tarnish your memory of it with a rather pointless wrangle, forgive me if I suggest that we now just agree to disagree!

Regards

Bellerophon


User currently offlineGDB From United Kingdom, joined May 2001, 13256 posts, RR: 77
Reply 15, posted (11 years 6 months 2 days 19 hours ago) and read 1711 times:

Some illustrations for Bellerphon's posts;

http://www.concordesst.com/inside/cockpittour/flightcontrols/pedframe.html

http://www.concordesst.com/powerplant.html

Not a totally up to date flight deck for a service aircraft pictured, but the pics of the throttle/reheat controls give a good idea of them!



User currently offlineMirrodie From United States of America, joined Apr 2000, 7444 posts, RR: 62
Reply 16, posted (11 years 6 months 2 days 19 hours ago) and read 1696 times:
Support Airliners.net - become a First Class Member!

Bellerphon and GDB, thanks to your insight again! They are so appreciated! I love absorbing this knowledge and learning from good people.

Bellerphon, if I may, either the Concordes are all retired or when you decide to one day retire, will you ever let us in on who you are?

I mean, hey, if I am talking to a great pilot that I might have heard of, I would love to know! Big grin

(its like wondering if John Travolta is here, maybe posing as KROC or GDB.)


regards, mirrodie



Forum moderator 2001-2010; He's a pedantic, pontificating, pretentious bastard, a belligerent old fart, a worthless st
User currently offlineSvtdriver From United States of America, joined Jun 2003, 5 posts, RR: 0
Reply 17, posted (11 years 6 months 2 days 5 hours ago) and read 1648 times:

I wonder if he's the one who piloted my Concorde flight!  Smile

User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
Reply 18, posted (11 years 6 months 2 days 1 hour ago) and read 1626 times:

Really interesting thread.

Concorde makes its acceleration from M1.7 to 2.0 while in cruise climb if I recall once the reheaters have been shut down. Isn't the altitude passed once the reheaters have been shut down in the order of FL400 (can't remember exactly)?

Can she maintain level flight at say FL400 and get a quicker acceleration to 2.0 or are there compressibility/fuel transfer issues preventing such?

She will be missed once officially retired. I think I read the other day that BA will keep one aloft for publicity reasons but off the scheduled list of flights.

A glimmer of hope. But probably not something Sir Richard will be happy with...


User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 19, posted (11 years 6 months 1 day 18 hours ago) and read 1587 times:

Yikes!

Good afternoon, and thank you for your recent kind e-mail.

To take your points in order.

...Concorde makes its acceleration from M1.7 to 2.0 while in cruise climb...once the reheaters have been shut down...

Correct.

...Isn't the altitude passed once the reheaters have been shut down in the order of FL400...

It will be nearer 43,200 ft on an ISA day, but in fact the re-heats are cancelled on achieving M1.7, rather than on passing a given altitude. Passing through FL400 the Mach number would be between M1.42 to M1.50, dependent on aircraft weight.

...Can she maintain level flight at say FL400...

Supersonic, yes, but only for a short time and highly undesirable. She would still be in a relatively high drag region, re-heats still required with their consequent very high fuel flows and with the clock running down against the time limit for the use of re-heat.

Subsonic, yes, but FL400 is far too high for an economical subsonic cruise at any weight.

…level flight……and get a quicker acceleration to 2.0…

No, and the reason is simply this.

Acceleration in level flight should not be possible, because Concorde should already be at the maximum speed allowed for that altitude.

Concorde flies at her (highly variable) VMO whenever possible, and when I say that, I mean it quite literally, to the knot. If she were to level off at any altitude, she should already be at her VMO, for that altitude, and to fly any faster, as an IAS, would generate an overspeed warning.

I know you will understand, but for the benefit of others who may possibly be interested, allow me to expand on this a little, and please forgive me the occasional simplification or generalisation as I do so!

In level flight, flying at the maximum IAS permitted at that altitude, there are only three ways for Concorde to increase her Mach number.

Firstly, if still below the tropopause, climb higher at a constant IAS and as the OAT falls, the Mach number will increase. Most subsonic aircraft do this anyway, climbing at a constant IAS (though not generally VMO!) until reaching their desired Mach number, when they will transition to a constant Mach number for the rest of the climb.

Secondly, if at FL400, as in your example, and now (probably) above the tropopause, the OAT will (in theory) remain constant at -56.5°C and won’t fall as she climbs, so this technique won’t work. In order to increase Mach number now, climb, and utilise the fact that Concorde’s VMO increases steadily by 10kts per 1,000 ft above the tropopause, and that by climbing she can now gradually increase her IAS, and thus her Mach number.

Thirdly, at around FL440, Concorde’s VMO stops increasing, and stays at 530 kts IAS for the rest of the cruise/climb. Now, with no further IAS increase possible, and no OAT decrease likely, the only way to increase Mach number still further is to climb at 530 kts IAS and utilise the fact that during a climb at fixed IAS, as the ambient air density decreases, her TAS, and hence her Mach number, will both rise.

There are also nose temperature limits (TMO) which, for the sake of simplicity, I haven’t gone into, but the common thread is that Concorde needs to climb in order to accelerate.

Regards

Bellerophon


User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
Reply 20, posted (11 years 6 months 1 day 17 hours ago) and read 1569 times:

Brilliant Bellerophon. Well understood, with thanks! I guess I was somewhat on the right track by thinking compressibility issues were involved. As far as my using FL400 as an example, it's been so long since my single flight (seat 8A!) I've forgotten the specifics. I too kept a diary of my experience but don't have access to it to ask more specific questions.

Once again, thanks for the detailed reply.

Although I'm a fairly recent handle on A.Net, I was a quite frequent poster here prior to 9-11 under a different handle.

Some have already figured it out, methinks...  Big grin


User currently offlineGordonroxburgh From United Kingdom, joined Jul 2000, 550 posts, RR: 20
Reply 21, posted (11 years 6 months 11 hours ago) and read 1491 times:

I was looking at the figures from my "round the bay" flight with Air France:

M0 - M0.95 : 7 mins
Subsonic criuse to coast : around 5-7 mins
M0.95 - M1.0 : around 60 seconds
M0 - M2.00 : 29 mins (with the 5-7 min subsonic cruise)

Now here's my question for our resident expert (Bellerophon)

If enough people in the cabin were up for it and nobody objected, is there anything operationally or technically stopping all 4 re-heats being re-engaged together, to let people feel the true power of Concorde?

Maybe this is something for the the BA "Round the Bays"!!

Another great post in this forum, I'll save the info the the "Flight profile section" of my website, which one day I'll get on line Smile/happy/getting dizzy

Gordon.


User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 22, posted (11 years 6 months 10 hours ago) and read 1495 times:

Gordonroxburgh

...is there anything operationally or technically stopping all 4 re-heats being re-engaged together, to let people feel the true power of Concorde?...

No, not really, and not that long ago all four re-heats were frequently selected ON together, producing a more noticeable single "nudge", which proved very popular on charter flights!

However, whilst the nudge itself is not a problem, one must consider the possibility that two re-heats, both on the same wing, might fail to light up when selected, whilst the two re-heats on the other wing light up as normal.

This would result in a fair amount of asymmetric thrust, and a consequent yawing motion towards the failed re-heats. Nothing to be alarmed about, and easily controlled by the pilot, but probably noticeable in the passenger cabin.

Selecting the re-heats on two at a time, in symmetrical pairs (engines 1&4 and then engines 2&3) guards against this possibility, and reduces any potential asymmetry to that of a single re-heat.

It also makes life a little easier on the F/E, who would have twice as many gauges to monitor if all four re-heats were selected together, and it reduces the rate at which the pilot has to pitch the nose up, if all that extra power comes in more slowly.

For these reasons, whilst not prohibited, most crews seem to feel it is better airmanship, if a little less exciting, to select the re-heats on in pairs.

Regards

Bellerophon


User currently offlineGordonroxburgh From United Kingdom, joined Jul 2000, 550 posts, RR: 20
Reply 23, posted (11 years 5 months 4 weeks 1 day 2 hours ago) and read 1435 times:

Bellerophon

Thanks for your reply.

Aside from the expereince of a lightweight take off, on a flight I flew on the memories was the sheer power you feel when the throttles were pushed forward and the reheats applied. It really gives you the feeling of Concorde wanting to go to where she was designed to go....as if she was being unleased.

I guess we got to make sure the champers does not get spilt back in the cabin!


User currently offlineFrancoflier From France, joined Oct 2001, 3849 posts, RR: 11
Reply 24, posted (11 years 5 months 3 weeks 4 days 7 hours ago) and read 1344 times:

This definitely is a great thread.

I'd like to abuse of Bellerophon's patience and experience again for this question, somewhat related to an earlier post by Yikes! :

What is the lowest altitude (if any) at which the concorde can fly supersonic?

Sorry to bother, but I have to say, if I were a concorde pilot, I'd be talking about it every day for the rest of my life...



Looks like I picked the wrong week to quit posting...
User currently offlineBellerophon From United Kingdom, joined May 2002, 585 posts, RR: 59
Reply 25, posted (11 years 5 months 3 weeks 4 days 2 hours ago) and read 1366 times:

Francoflier

...What is the lowest altitude (if any) at which the concorde can fly supersonic?...

There is definitely a lowest altitude for supersonic flight on Concorde, as she can only fly really fast at altitude. At sea level, her maximum speed is in fact quite a bit slower than a B747.

Assuming that the air temperatures at altitude are standard, a heavy Concorde, at transatlantic weight, should become supersonic climbing through around 28,500 ft.

A light Concorde, on a charter flight, would need to climb a bit higher, and should become supersonic around 31,000 ft.

Regards

Bellerophon


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