LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 2:56 pm

Hi everybody,

A question that has been playing around my cranium for a while. And since I signed up today I can finally ask some real experts;

When looking at the thrust to weight ratio of Concorde:

MTOW: 408 000lbs
Total thrust: 128 000lbf
Total thrust: 152 000lbf (with A/B)

Thrust/Weight: 0,314
Thrust/Weight: 0,373 (with A/B)

And compare that to your standard sub-sonic 757-200:

MTOW: 255 000lbs
Total thrust: ~80 000lbf

Thrust/Weight: 0,314

You'll notice that the values without afterburner are virtually the same. Knowing that Concorde did Mach 2.something in super-cruise, so without the afterburner, I am wondering how this is possible? Is it all due to the better aerodynamics that Concorde achieved more then double the speed of a 757? Or did the Concorde engines remain at full thrust the entire flight? Something else I haven't thought about?

Regards,
Joost
 
wilco737
Posts: 7279
Joined: Sun Jun 20, 2004 12:21 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 3:01 pm

The aerodynamics change a lot once you have past the sound barrier! You need hell of a lot more thrust to pass the sound barrier than actually flying faster than the sound. The area from M0.90 to M1.2 the drag increases amazingly and therefore the Concorde needed the A/B. But once faster than M1.2 the A/B were switched off and the thrust of the engines were sufficient to accelerate the Concorde to M2.0!
The air in the altitudes the Concorde was flying is very thin! Concorde was flying at 55,000 feet or so and normal jetliner are flying roughly 40,000 feet. So the higher you fly, the lower the drag from the air because the air is thinner, so less thrust required to accelerate or to maintain your speed. That was a great advantage of the Concorde! But its fuel flow was amazingly high as well...

WILCO737 (MD11F)


P.S.: WELCOME TO AIRLINERS.NET! Enjoy it and have fun!  thumbsup 

[Edited 2008-02-20 07:07:10]
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 3:13 pm

Thanks Wilco!

Reading your posts I realized I knew the fact about the drag around mach 1, just didn't put it together  Wink Would that transistional phase of going supersonic also be the point where the skin temp would be at max value? I always thought the skin temperature was the highest at the highest speed.

Regards,

Joost
 
wilco737
Posts: 7279
Joined: Sun Jun 20, 2004 12:21 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 3:16 pm



Quoting LockstockNL777 (Reply 2):
also be the point where the skin temp would be at max value? I always thought the skin temperature was the highest at the highest speed.

Duh, good question! I think the highest skin temperature will be reached at highest speed - I think! but I dont know for sure...

Ah the good old times of Concorde! R.I.P. old lady! We all miss and love you  cloudnine 

WILCO737 (MD11F)
 airplane 
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 3:32 pm



Quoting WILCO737 (Reply 3):
Ah the good old times of Concorde! R.I.P. old lady! We all miss and love you

Hear hear! I only once experienced the thunderous roar of that sexy old lady (would it go to far to apply the MILF designation? Wink), and I was too little to understand how special that was... well, enough melancholy for one day  Wink
 
wilco737
Posts: 7279
Joined: Sun Jun 20, 2004 12:21 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 3:36 pm



Quoting LockstockNL777 (Reply 4):
Hear hear! I only once experienced the thunderous roar of that sexy old lady (would it go to far to apply the MILF designation? Wink), and I was too little to understand how special that was... well, enough melancholy for one day Wink

 rotfl  nicely said! I have been to LHR several times and heard and saw her there  cloudnine 

WILCO737 (MD11F)
 airplane 
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 4:35 pm



Quoting WILCO737 (Reply 1):
The area from M0.90 to M1.2 the drag increases amazingly and therefore the Concorde needed the A/B

I believe it could accelerate through M1 without afterburners but it was more efficient to do so with them.
 
wilco737
Posts: 7279
Joined: Sun Jun 20, 2004 12:21 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 4:44 pm



Quoting David L (Reply 6):
I believe it could accelerate through M1 without afterburners but it was more efficient to do so with them.

Ok, maybe they werent really needed, but it was for sure easier to accelerate above M1.0 with the A/B...

WILCO737 (MD11F)
 airplane 
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 5:46 pm



Quoting WILCO737 (Reply 7):

And don´t forget the incredible cool-factor...just imagine, a MD11 with afterburners....rrrrrrrrrrr
 
BAE146QT
Posts: 981
Joined: Sun Sep 24, 2006 4:58 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 5:51 pm



Quoting LockstockNL777 (Reply 4):
(would it go to far to apply the MILF designation?)

It would be grammatically incorrect since;

a) The Concorde was no-one's mother as far as I know and,
b) I don't think it would have any external orifices suitable for the activity you propose unless you're a blue whale, (or a gerbil - I'm thinking 'pitot tube' here.)

Welcome to A.NET anyway, you crazy Dutch person you.

Quoting David L (Reply 6):
I believe it could accelerate through M1 without afterburners but it was more efficient to do so with them.

Really? I never knew that.

I can see why it would be inefficient (lower rate of fuel burn but for a far longer time) but I had no idea it could theoretically/actually do that.
Todos mis dominós son totalmente pegajosos
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 5:51 pm



Quoting WILCO737 (Reply 7):
Ok, maybe they werent really needed, but it was for sure easier to accelerate above M1.0 with the A/B...

Sorry, I wasn't disagreeing with you, just adding some more information.  Smile
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 6:03 pm



Quoting BAe146QT (Reply 9):
Welcome to A.NET anyway, you crazy Dutch person you.

Well thank you!

Quoting BAe146QT (Reply 9):
It would be grammatically incorrect since;

a) The Concorde was no-one's mother as far as I know and,
b) I don't think it would have any external orifices suitable for the activity you propose unless you're a blue whale, (or a gerbil - I'm thinking 'pitot tube' here.)

Yes I did realise that while posting. But with the first FADEC and sort-of-fly-by-wire you could call, while bending the laws of logic a bit, it a mother of modern airliners.. (bit=a lot)

Cheers!
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 6:27 pm



Quoting BAe146QT (Reply 9):
Really? I never knew that.

Well, I'd hold on until GDB, Bellerophon and/or "Little" Vc10 get here.  duck 
 
vc10
Posts: 1341
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 6:30 pm

The drag did not start to decrease until Concorde had accelerated past Mach1.4 and the reheats were switched off at Mach 1.7 or after 15 mins of use whichever came soonest. If I remember correctly in commercial use you would not start an acceleration unless you had at least 3 reheats. After the reheats were switched off at M1.7 or even more so after 15 mins if the OAT was high then it could be a long slow acceleration to cruise height and speed

The highest skin temps [Max 127deg C] was reached at cruising speed especially in the higher latitudes where the OAT was warmer. In tropical latitudes skin temps were never a problem.

The max forward position of the throttles gave the power that was selected on the rating switches these being Take-off,
Climb and Cruise and shortly after take-off Climb position would be selected on the rating switches which meant that at full throttle the power would be restricted to Climb Power. Once in Mach 2.0 cruise then the rating would be selected to Cruise Power. The Throttles would be selected fully forward for supersonic acceleration [M0.95] and would stay there until the descent phase of flight

Some say Concorde was the mother of Airbus  stirthepot 

littlevc10
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 6:57 pm



Quoting Vc10 (Reply 13):

thanks for the info vc10!

BTW: why is the OAT higher at the upper latitudes? I would expect it would be warmer near the equator, even in the upper atmosphere, but I understand they aren´t?
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 7:30 pm

It's the opposite of what you'd think, OAT being cooler the equatorial regions, at 50,000 feet and above.
Making the engines in supercruise even more efficient, added to the range.
This was first apparent on the short lived LHR-BAH-SIN, on the BAH-SIN leg.

Later, after building up operational experience with one stop flights, the seasonal LHR-BGI service became non stop (most of the time!).
When you consider that BGI is not, as many think, part of the Caribbean chain, but is in fact off the coast of Venezuela, you can see how this route could be non-stop by having a chunk of that cooler equatorial upper atmosphere, as part of the sector.
This longer sector, (around 4 hours 10 min) compared to LHR-JFK or LHR-IAD, meant that the aircraft usually reached 60,000 ft rather than the usual around 57-58,000.
As I saw myself in my last Concorde, the last supersonic international and G-BOAE's final flight, to retirement in BGI.
 
BAE146QT
Posts: 981
Joined: Sun Sep 24, 2006 4:58 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 8:04 pm



Quoting LockstockNL777 (Reply 11):
Well thank you!

You're welcome!

Quoting LockstockNL777 (Reply 11):
But with the first FADEC and sort-of-fly-by-wire you could call, while bending the laws of logic a bit, it a mother of modern airliners..

I still think you're stretching the metaphor, sir. And planes are no good for a nice chat and a cuddle unless your bed is vast. I expect you will have to settle for the same relationship that the rest of us have with hardware.

Quoting David L (Reply 12):
Well, I'd hold on until GDB, Bellerophon and/or "Little" Vc10 get here.

I could have held my breath for as long as it took. 3 minutes later...

Quoting Vc10 (Reply 13):
The highest skin temps [Max 127deg C] was reached at cruising speed especially in the higher latitudes where the OAT was warmer. In tropical latitudes skin temps were never a problem.

This is counter-intuitive, though I don't dis-believe you of course. To mirror Lockstock's question, do you have a good link that explains this? Seems to me that the equator is always closer to the sun and should be hotter. Is the air thinner because it is warmer? Is that why the total heating is lower?

Quoting Vc10 (Reply 13):

Some say Concorde was the mother of Airbus

They may have a point, to some degree. But it's a big leap. I wonder if our Concorde pilots are now flying Airbus aircraft? If so, I bet the experience is quite different. Concorde was quite a specialist bird. Has its DNA filtered down?
Todos mis dominós son totalmente pegajosos
 
LockstockNL777
Topic Author
Posts: 53
Joined: Wed Feb 20, 2008 11:33 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 8:51 pm



Quoting BAe146QT (Reply 16):
Quoting Vc10 (Reply 13):
The highest skin temps [Max 127deg C] was reached at cruising speed especially in the higher latitudes where the OAT was warmer. In tropical latitudes skin temps were never a problem.

This is counter-intuitive, though I don't dis-believe you of course. To mirror Lockstock's question, do you have a good link that explains this? Seems to me that the equator is always closer to the sun and should be hotter. Is the air thinner because it is warmer? Is that why the total heating is lower?

If I would guess I would say that the hot lower regions of air near the equeatour ascent to higher regions, cool down there. And would then be "transported" to the north and south due to the earth rotation (or something completly else, just guessing here) and be warmed up a bit along the way. Maybe interaction with solar radiation which is more intense near the poles?
 
vc10
Posts: 1341
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 10:07 pm

In very broad terms the atmosphere cools by about 2 deg C per 1000 ft up to the tropapause where the temp remains the same for some gain in height. The tropopause height varies with latitude being lower nearer the poles than the equator
On Concorde's N.Atlantic track the tropopause would be some where about 35,000 so let us say 35000 for the example

Ground level temperature 15 degs C Lapse rate 2 deg C /1000ft

Temp at 35000ft 2 x 35 = 70 minus 15 = Minus 55 deg C . Now in Concorde's Flight envelope no further temp decrease will take place so
Temp at 50000ft = minus 55 deg C


At the equator the tropopause is higher say 50000ft then

Temp on ground 30degs C Lapse rate 2 Deg C/1000ft

Temp at 50000ft is 2 x 50 =100 minus 30 = minus 70 degC

The following site might help

http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html

http://www-mdp.eng.cam.ac.uk/library...mal_dvd_only/aero/atmos/atmos.html

littlevc10
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 20, 2008 10:19 pm



Quoting BAe146QT (Reply 16):
Seems to me that the equator is always closer to the sun and should be hotter.

Actually, in the northern hemisphere, the earth is closer to the sun during winter. It's the tilt of the earth's axis that causes it to be warmer in summer. The point being that "it isn't that simple".  Smile

I vaguely remember that the reasons given above for Concorde being able to cruise higher nearer the equator were to do with the tropopause being higher there.

Quoting BAe146QT (Reply 16):
Quoting Vc10 (Reply 13):

Some say Concorde was the mother of Airbus

They may have a point, to some degree. But it's a big leap.

I think Vc10 means that it lead to the creation of the Airbus consortium, not specifically of the technicalities of the FBW aircraft. However, look at Concorde with the visor fully down and you can see a resemblance in that area.  Smile
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Thu Feb 21, 2008 6:20 pm

Well she was the first collaborative project, in a major civil airliner at least.
Airbus surely learned lessons, including how NOT to do it, from Concorde.
 
BAE146QT
Posts: 981
Joined: Sun Sep 24, 2006 4:58 am

RE: Concorde Thrust To Weight Ratio Compared

Thu Feb 21, 2008 7:37 pm

I had to read it a few times, but I get it now. Cheers, VC10.

Incidentally, does anyone know why it is that the French have such a liking of delta-winged (and double-delta) aircraft?
Todos mis dominós son totalmente pegajosos
 
luv2cattlecall
Posts: 627
Joined: Fri Sep 28, 2007 6:25 am

RE: Concorde Thrust To Weight Ratio Compared

Fri Feb 22, 2008 2:24 pm



Quoting WILCO737 (Reply 1):
The area from M0.90 to M1.2 the drag increases amazingly and therefore the Concorde needed the A/B. But once faster than M1.2 the A/B were switched off and the thrust of the engines were sufficient to accelerate the Concorde to M2.0!

Makes you wonder what Boeing was thinking with the whole Sonic Cruiser idea...! I'm still convinced that the whole purpose of that was to distract Airbus while they were cooking up the 7E7.
.
 
ConcordeBoy
Posts: 16852
Joined: Thu Feb 01, 2001 8:04 am

RE: Concorde Thrust To Weight Ratio Compared

Mon Feb 25, 2008 4:17 pm



Quoting GDB (Reply 15):
When you consider that BGI is not, as many think, part of the Caribbean chain, but is in fact off the coast of Venezuela, you can see how this route could be non-stop by having a chunk of that cooler equatorial upper atmosphere, as part of the sector.

Interesting.

Taking that into consideration-- do you think the MIA flights could've (operationally-speaking) gone nonstop as well?
Faire du ciel le plus bel endroit de la terre c'est impossible sans Concorde!
 
User avatar
mighluss
Posts: 965
Joined: Tue Oct 02, 2001 12:11 am

RE: Concorde Thrust To Weight Ratio Compared

Tue Feb 26, 2008 1:08 am



Quoting LockstockNL777 (Reply 8):
just imagine, a MD11 with afterburners....rrrrrrrrrrr


MyAviation.net photo:
Click here for bigger photo!
Photo © Martin Oertle



 Big grin ... sorry, coundn't resist.
Miquel.
 
wilco737
Posts: 7279
Joined: Sun Jun 20, 2004 12:21 am

RE: Concorde Thrust To Weight Ratio Compared

Tue Feb 26, 2008 6:38 am



Quoting Mighluss (Reply 24):
Big grin ... sorry, coundn't resist.

hehe, very nice! Big grin

WILCO737 (MD11F)
 airplane 
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Tue Feb 26, 2008 12:08 pm



Quoting VC10 (Reply 18):

It only took me five days to notice but you covered the tropopause issue so completely while I was posting that my comment was utterly worthless - sorry!  embarrassed 
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Tue Feb 26, 2008 6:50 pm



Quoting ConcordeBoy (Reply 23):
Taking that into consideration-- do you think the MIA flights could've (operationally-speaking) gone nonstop as well?


That's something I'll have to ask someone who was on the fleet, when the IAD-MIA sector ran, from 1984-91.
If someone here knows for sure?
 
vc10
Posts: 1341
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Thrust To Weight Ratio Compared

Tue Feb 26, 2008 8:19 pm

The memory is failing a bit now, but London- Barbados stretched the Concorde to it's limit and London -Miami is an even longer route so basically no it would not have been possible with a commercial load.

What also made the London - Barbados route possible was

1] Quiet arrival time at Barbados with a simple flight route from top of supersonic decel to landing. Barbados ATC were very good to Concorde. Usually Concorde was given also a straight out climb and accel from Barbados ATC which saved the old girl a lot of fuel [ No Land to worry about]

2] A few reasonable on route refuelling stops, should that be required, such as Shannon and Lisbon for example

3] Santa Maria for on route alternate

4] Decel and routing up the English Channel on way home which again saved fuel.

All this special treatment just would not have been available in a busy airport like Miami

Also the Miami extension was just a trial [even if it was a long one] to try and improve the profitability of the LHR- IAD route, as the aircraft would have night stop IAD anyway so using it for the IAD-MIA-IAD sectors did not require an extra aircraft. The Crew did LHR-IAD-MIA, night stop and return to London so no extra crew needed . However It never did commercially live up to expectations

It was very popular with the crew as it allowed them to see the sun during the winter , which was quite important when all you did was LHR-JFK [ I can hear all of your groans of sympathy]

A lot of Concorde's operation was beyond what was initially expected of it,but LHR MIA would have been pushing it too far, although I seem to remember a Concorde on a positioning flight did do MIA LHR direct but it was empty and I could be wrong on that.[ memory getting vague again ]

A lot has been said about Concorde's operation, but I have to say that generally not enough credit publicly, has ever been given to the Air Traffic Controllers who whilst staying within the rules and without showing favouritism would still bend over backwards to facilitate any request from Concorde's crew . I think they almost saw it as a challenge. This flexibility definately helped the London--Barbados route

littlevc10

[Edited 2008-02-26 12:21:04]
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 27, 2008 1:39 am



Quoting LockstockNL777 (Thread starter):
You'll notice that the values without afterburner are virtually the same. Knowing that Concorde did Mach 2.something in super-cruise, so without the afterburner, I am wondering how this is possible?

Thrust/weight ratio is very rarely instructive for cruise performance. It's driven almost entirely by takeoff speed, takeoff drag, and MTOW. None of those three figure into cruise very well. Concorde needed a longer runway and higher takeoff speeds, which allowed the "low" thrust/weight ratio (relative to a conventional airliner) to get it off the ground.

Quoting LockstockNL777 (Reply 2):
Would that transistional phase of going supersonic also be the point where the skin temp would be at max value? I always thought the skin temperature was the highest at the highest speed.

Skin temp maxes out at max speed. The drag rise as you go through the sound barrier is primarily wave drag (pressure drag) due to the formation of shock waves. As you increase speed even more, the stagnation temperature of the air continues to rise and the temperature jump across the shock waves also goes up.

Tom.
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 27, 2008 5:08 pm

Thanks VC10, MIA making IAD more profitable was the impression I got, or thought so, my own memory isn't perfect on this.
Also, I just was not sure about the distance from LHR, to MIA as well as all the other factors.

I completely concur that we had some terrific support, beyond the obvious in the airline, from industry etc.
That last emotional message from ATC, as G-BOAF prepared to depart on the very last Concorde flight in Nov 2003, said it all really.

Now, if we had got some of these, MIA non stop would have been possible;
www.concordesst.com/concordeb.html

If only!
(Might still be flying this model today).
 
Rj111
Posts: 3007
Joined: Wed Sep 08, 2004 9:02 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 27, 2008 8:36 pm



Quoting LockstockNL777 (Thread starter):
Or did the Concorde engines remain at full thrust the entire flight? Something else I haven't thought about?

It's engines design cruise thust is around 10kbl each, which is comparable to a Trent 553 of an A340-500 (11lkb).

Quoting Tdscanuck (Reply 29):
Concorde needed a longer runway and higher takeoff speeds, which allowed the "low" thrust/weight ratio (relative to a conventional airliner) to get it off the ground.

What? It needed a longer runway because it needed a higher takeoff speed. If it did not require the high thrust to weight ratio for take off do you think it would use the reheat - more than doubling the fuel consumption? Delta wings perform poorly subsonically, though Concorde's wing was an extremely advanced delta wing which had to address this problem adequately, without compromising the supersonic performance too heavily.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Feb 27, 2008 10:23 pm



Quoting RJ111 (Reply 31):
Quoting Tdscanuck (Reply 29):
Concorde needed a longer runway and higher takeoff speeds, which allowed the "low" thrust/weight ratio (relative to a conventional airliner) to get it off the ground.

What? It needed a longer runway because it needed a higher takeoff speed. If it did not require the high thrust to weight ratio for take off do you think it would use the reheat - more than doubling the fuel consumption? Delta wings perform poorly subsonically, though Concorde's wing was an extremely advanced delta wing which had to address this problem adequately, without compromising the supersonic performance too heavily.

I'm really not following you here. Concorde needed a high takeoff speed because of the delta wing. High takeoff speed coupled with normal thrust/weight ratio means a long runway. But I can't tell if we're agreeing or not.

Tom.
 
Rj111
Posts: 3007
Joined: Wed Sep 08, 2004 9:02 am

RE: Concorde Thrust To Weight Ratio Compared

Thu Feb 28, 2008 10:13 am

Concorde didn't have a normal or low thrust/weight ratio on takeoff is the point, it had a very high one.

High take off speed means you have to accelerate to your higher take off speed in less time than a slower aircraft if you want to use the same length of runway. Of course, Concorde used more runway, but it shows how small increases in TO speed more than proportionally increases the need for acceleration. Meaning even with a long runway, Concorde still needed a very high thrust.
 
User avatar
cpd
Posts: 4574
Joined: Sat Jun 28, 2008 4:46 am

RE: Concorde Thrust To Weight Ratio Compared

Thu Feb 28, 2008 10:23 am



Quoting VC10 (Reply 28):

A lot of Concorde's operation was beyond what was initially expected of it,but LHR MIA would have been pushing it too far, although I seem to remember a Concorde on a positioning flight did do MIA LHR direct but it was empty and I could be wrong on that.[ memory getting vague again ]

I would be interested in what route it used on that flight (eg, INS co-ordinates). Do know, or would you be able to hazard a guess which one it used?

Would I be correct in assuming it went via SL1 for the obvious fuel savings?
 
Oryx
Posts: 123
Joined: Fri Nov 18, 2005 9:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Fri Feb 29, 2008 5:15 pm

I suppose that the Olympus engines had a very low bypass-ratio. This should have imposed relatively low thrust at low velocities in favour of higher thrust at cruise speed. When comparing the thrust to weight ratio, Mach number is of interest.
 
BAE146QT
Posts: 981
Joined: Sun Sep 24, 2006 4:58 am

RE: Concorde Thrust To Weight Ratio Compared

Fri Feb 29, 2008 7:07 pm

VC10 spaketh thus...

Quoting VC10 (Reply 28):
I think they almost saw it as a challenge. This flexibility definately helped the London--Barbados route

Not commenting on any particular aspect of your post - just wanted to say thank you for posting it. Much appreciated.
Todos mis dominós son totalmente pegajosos
 
vc10
Posts: 1341
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Thrust To Weight Ratio Compared

Fri Feb 29, 2008 7:11 pm



Quoting Oryx (Reply 35):
I suppose that the Olympus engines had a very low bypass-ratio

No, the Olympus was a true turbo jet, however the use of the Primary Nozzle program could alter the relative speed of the low and High pressure compressors to make the engine more efficient/safe for the different phases of flight

Quoting Cpd (Reply 34):
I would be interested in what route it used on that flight (eg, INS co-ordinates

I am sorry but it was all a long time ago now, so cannot help you there. It is like a lot of things in life where you never think anybody in the future would be interested, so do not record things in detail

littlevc10
 
Analog
Posts: 1193
Joined: Fri Jul 14, 2006 3:24 am

RE: Concorde Thrust To Weight Ratio Compared

Fri Feb 29, 2008 9:43 pm



Quoting David L (Reply 19):

Actually, in the northern hemisphere, the earth is closer to the sun during winter. It's the tilt of the earth's axis that causes it to be warmer in summer. The point being that "it isn't that simple".

You're closest to the sun when the sun is directly overhead, which only happens between the Tropics of Cancer and Capricorn. On June 21 or so Paris and the equator are almost equidistant to the sun (at noon).

Quoting VC10 (Reply 37):
Quoting Oryx (Reply 35):
I suppose that the Olympus engines had a very low bypass-ratio

No, the Olympus was a true turbo jet,

So it had a very low bypass ratio: 0:1.  Wink What about the secondary air doors? The air that passes through them and into the afterburner is bypass of sorts, but it doesn't get acted on by any fan. Is there a term other than "bypass" for this bypass air?

Shouldn't it be "Olympus was a true turbo jet."? After all, it's part of the non-countable noun "Concorde" (like "Air contains oxygen.") Of course then you cannot say that "Concorde had four Olympus..." you'd have to say "Concorde had four examples of Olympus."

Quoting Vc10 (Reply 13):
If I remember correctly in commercial use you would not start an acceleration unless you had at least 3 reheats.

So you could leave the gate with a defective afterburner?

Does this have any relationship to the special nature of the #4 engine? http://www.concordesst.com/powerplant.html (bottom of the page).
 
User avatar
cpd
Posts: 4574
Joined: Sat Jun 28, 2008 4:46 am

RE: Concorde Thrust To Weight Ratio Compared

Sat Mar 01, 2008 1:38 am



Quoting VC10 (Reply 37):

I am sorry but it was all a long time ago now, so cannot help you there. It is like a lot of things in life where you never think anybody in the future would be interested, so do not record things in detail

That's okay - no problems.  Smile I'll make a few educated guesses.
 
Bellerophon
Posts: 516
Joined: Thu May 09, 2002 10:12 am

RE: Concorde Thrust To Weight Ratio Compared

Sat Mar 01, 2008 3:03 am

Analog


...You're closest to the sun when the sun is directly overhead...

A popular misconception, but still a misconception..


DavidL was indeed correct when he said:

...in the northern hemisphere, the earth is closer to the sun during winter...

The angle the midday Sun makes with the horizon does not determine the distance the Sun is from the Earth.


...So you could leave the gate with a defective afterburner?...

In certain circumstances, it was allowable to despatch with one re-heat unserviceable, not something I ever did, but quite possibly something Vc10 may well have done!

At lighter T/O weights, generally on Eastbound flights,it was frequently possible to continue a take-off, after a single re-heat failure during the take-off roll, and this did occur from time to time.

The re-heat system itself was more reliable than the re-heat indicating system, so a lot of the apparent re-heat failures (which sometimes led to a rejected take-off) were merely indication failures rather than actual failures.

Two re-heats were the minimum number needed for the transonic acceleration, M0.95 to M1.7.


Best regards

Bellerophon
 
Analog
Posts: 1193
Joined: Fri Jul 14, 2006 3:24 am

RE: Concorde Thrust To Weight Ratio Compared

Sat Mar 01, 2008 4:47 am



Quoting Bellerophon (Reply 40):

...You're closest to the sun when the sun is directly overhead...

A popular misconception, but still a misconception..


Really? At any given time. where on Earth are you closer to the sun than the spot where the Sun is directly overhead?

Quoting Bellerophon (Reply 40):

DavidL was indeed correct when he said:

...in the northern hemisphere, the earth is closer to the sun during winter...

That's true, but mostly because Earth's orbit is not a circle. Earth passes closest to the sun right around the new year (is that a coincidence?). So the absolute closest any point on Earth gets to the sun is probably at some point a bit north of the Tropic of Capricorn.
 
prebennorholm
Posts: 6418
Joined: Tue Mar 21, 2000 6:25 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Mar 05, 2008 8:17 pm



Quoting Analog (Reply 41):
At any given time. where on Earth are you closer to the sun than the spot where the Sun is directly overhead?

We are closest to the sun on 4th January - some 147 million km - and furthest away on 5th July - some 151 million km.

The annual variation in earth to sun distance - some 4 million km - is a few hundred times more than the diameter of the earth. Therefore it obviously means practically nothing where on earth you are placed.

Only the variation in earth to sun distance is roughly ten times more than the distance to the moon.
Always keep your number of landings equal to your number of take-offs
 
Analog
Posts: 1193
Joined: Fri Jul 14, 2006 3:24 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Mar 05, 2008 9:58 pm



Quoting Prebennorholm (Reply 42):

We are closest to the sun on 4th January - some 147 million km - and furthest away on 5th July - some 151 million km.

I already confirmed that, but my statement that at any given time, the spot on Earth that is closest to the sun is the spot where the sun is directly overhead, is still correct. It even holds true on Jan. 4, the closest you can get to the sun while on Earth is still a spot where the sun is directly overhead (at the time when the Earth is closest to the sun).

To put it another way, at the exact moment on Jan. 4 when Earth is at it's closest to the Sun, where on the planet are you closest? Wherever the Sun is directly overhead, somewhere close to the Tropic of Capricorn.
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Mar 05, 2008 10:01 pm



Quoting Analog (Reply 41):
So the absolute closest any point on Earth gets to the sun is probably at some point a bit north of the Tropic of Capricorn.

Yes. During summer in the southern hemisphere at local noon.  Smile

All points between the Tropics of Cancer and Capricorn will see the sun overhead at some point at local noon during the year. Outside that region, the further you move towards the poles, the lower the sun gets at local noon in summer.

In summary, the variation in the angle at which the sun hits the earth's surface at a given location is more significant in terms of heat than the variation in distance from the sun throughout the year.
 
Analog
Posts: 1193
Joined: Fri Jul 14, 2006 3:24 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Mar 05, 2008 10:12 pm



Quoting David L (Reply 44):
All points between the Tropics of Cancer and Capricorn will see the sun overhead at some point at local noon during the year.

But only one point on each Tropic sees the sun directly overhead each year.  Smile
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Thrust To Weight Ratio Compared

Wed Mar 05, 2008 10:52 pm



Quoting Analog (Reply 45):
But only one point on each Tropic sees the sun directly overhead each year.

If you're making very sensitive measurements... I suppose so... technically.  Smile
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: Concorde Thrust To Weight Ratio Compared

Fri Mar 07, 2008 6:49 pm



Quoting Analog (Reply 38):
So you could leave the gate with a defective afterburner?

To add to other answers, put it this way, going with 3 reheats would be no great biggie on a LHR-LHR charter, with it's lower fuel uplift, take off weight.
But forget it on any BGI sector!
 
vc10
Posts: 1341
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Thrust To Weight Ratio Compared

Fri Mar 07, 2008 8:22 pm



Quoting Analog (Reply 38):

So it had a very low bypass ratio: 0:1. What about the secondary air doors? The air that passes through them and into the afterburner is bypass of sorts, but it doesn't get acted on by any fan. Is there a term other than "bypass" for this bypass air?

Yes, it was called powerplant cooling air, because that is what it was bled off the intake for.

Hope that helps, and as to the rest of your posting I am an old "oily",not an English pupil, but I am sure you are correct
 grumpy 

vc10

Who is online

Users browsing this forum: No registered users and 19 guests