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Concorde Thrust To Weight Ratio Compared  
User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Posted (6 years 5 months 1 week 22 hours ago) and read 7798 times:

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

48 replies: All unread, showing first 25:
 
User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 1, posted (6 years 5 months 1 week 22 hours ago) and read 7811 times:
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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]


It it's not Boeing, I am not going.
User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 2, posted (6 years 5 months 1 week 22 hours ago) and read 7794 times:

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


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 3, posted (6 years 5 months 1 week 22 hours ago) and read 7794 times:
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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 



It it's not Boeing, I am not going.
User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 4, posted (6 years 5 months 1 week 22 hours ago) and read 7784 times:



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


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 5, posted (6 years 5 months 1 week 22 hours ago) and read 7781 times:
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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 



It it's not Boeing, I am not going.
User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 6, posted (6 years 5 months 1 week 21 hours ago) and read 7765 times:



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.


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 7, posted (6 years 5 months 1 week 20 hours ago) and read 7758 times:
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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 



It it's not Boeing, I am not going.
User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 8, posted (6 years 5 months 1 week 19 hours ago) and read 7730 times:



Quoting WILCO737 (Reply 7):

And don´t forget the incredible cool-factor...just imagine, a MD11 with afterburners....rrrrrrrrrrr


User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 9, posted (6 years 5 months 1 week 19 hours ago) and read 7727 times:



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
User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 10, posted (6 years 5 months 1 week 19 hours ago) and read 7726 times:



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


User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 11, posted (6 years 5 months 1 week 19 hours ago) and read 7715 times:



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!


User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 12, posted (6 years 5 months 1 week 19 hours ago) and read 7709 times:



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

Well, I'd hold on until GDB, Bellerophon and/or "Little" Vc10 get here.  duck 


User currently offlineVc10 From United Kingdom, joined Nov 2001, 1406 posts, RR: 16
Reply 13, posted (6 years 5 months 1 week 19 hours ago) and read 7710 times:

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


User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 14, posted (6 years 5 months 1 week 18 hours ago) and read 7692 times:



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?


User currently offlineGDB From United Kingdom, joined May 2001, 13166 posts, RR: 78
Reply 15, posted (6 years 5 months 1 week 18 hours ago) and read 7677 times:

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.


User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 16, posted (6 years 5 months 1 week 17 hours ago) and read 7662 times:



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
User currently offlineLockstockNL777 From Netherlands, joined Feb 2008, 99 posts, RR: 0
Reply 17, posted (6 years 5 months 1 week 16 hours ago) and read 7648 times:



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?


User currently offlineVC10 From United Kingdom, joined Nov 2001, 1406 posts, RR: 16
Reply 18, posted (6 years 5 months 1 week 15 hours ago) and read 7625 times:

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


User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 19, posted (6 years 5 months 1 week 15 hours ago) and read 7614 times:



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


User currently offlineGDB From United Kingdom, joined May 2001, 13166 posts, RR: 78
Reply 20, posted (6 years 5 months 6 days 19 hours ago) and read 7481 times:

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.


User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 21, posted (6 years 5 months 6 days 18 hours ago) and read 7467 times:

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
User currently offlineLuv2cattlecall From United States of America, joined Sep 2007, 1650 posts, RR: 2
Reply 22, posted (6 years 5 months 5 days 23 hours ago) and read 7389 times:
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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.



When you have to breaststroke to your connecting flight...it's a crash!
User currently offlineConcordeBoy From , joined Dec 1969, posts, RR:
Reply 23, posted (6 years 5 months 2 days 21 hours ago) and read 7241 times:



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?


User currently offlineMighluss From Spain, joined Oct 2001, 945 posts, RR: 8
Reply 24, posted (6 years 5 months 2 days 12 hours ago) and read 7173 times:



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


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25 Post contains images WILCO737 : hehe, very nice! WILCO737 (MD11F)
26 Post contains images David L : 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 - so
27 GDB : 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?
28 VC10 : 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 i
29 Tdscanuck : Thrust/weight ratio is very rarely instructive for cruise performance. It's driven almost entirely by takeoff speed, takeoff drag, and MTOW. None of
30 Post contains links GDB : 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 ab
31 RJ111 : It's engines design cruise thust is around 10kbl each, which is comparable to a Trent 553 of an A340-500 (11lkb). What? It needed a longer runway bec
32 Tdscanuck : 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/weig
33 RJ111 : 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 accele
34 Cpd : 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?
35 Oryx : 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 t
36 BAe146QT : VC10 spaketh thus... Not commenting on any particular aspect of your post - just wanted to say thank you for posting it. Much appreciated.
37 VC10 : 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 compr
38 Post contains links and images Analog : 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 a
39 Post contains images Cpd : That's okay - no problems. I'll make a few educated guesses.
40 Bellerophon : Analog ...You're closest to the sun when the sun is directly overhead... A popular misconception, but still a misconception.. DavidL was indeed correc
41 Analog : Really? At any given time. where on Earth are you closer to the sun than the spot where the Sun is directly overhead? That's true, but mostly because
42 Prebennorholm : 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 t
43 Analog : 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
44 Post contains images David L : Yes. During summer in the southern hemisphere at local noon. All points between the Tropics of Cancer and Capricorn will see the sun overhead at some
45 Post contains images Analog : But only one point on each Tropic sees the sun directly overhead each year.
46 Post contains images David L : If you're making very sensitive measurements... I suppose so... technically.
47 GDB : 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 w
48 Post contains images VC10 : 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
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