SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 2:44 pm

I came accross this great cockpit video of a Concorde takeoff on youtube and I was wondering why when at takeoff do they advance the thrust lever from idle to takeoff power instantly?

Why do they not let the engines stabilize first for a couple of seconds first and then set the throttles to takeoff power?

http://uk.youtube.com/watch?v=ZnGhJSonKcI (2.35)


The second question is this. What doe's the metal "guard" in front of the fanblades of this Concorde engine do? I have also seen them on other aircraft engines too.

P.s I dont mean the flap that slows the air entering the engine. If you watch the start of this other video you should know what I mean.

http://uk.youtube.com/watch?v=f-nEKYthtm8


Thanks in advance for any replys.  

[Edited 2009-01-21 06:45:41]
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 3:39 pm



Quoting SpeedBirdA380 (Thread starter):
I came accross this great cockpit video of a Concorde takeoff on youtube and I was wondering why when at takeoff do they advance the thrust lever from idle to takeoff power instantly?

Because Concorde had a form of "throttle by wire", i.e. pre-FADEC type of computer (analogue?) that interpreted the throttle lever movements and took care of the details. I seem to recall that the swift movement from idle to take-off power wasn't just possible, it was preferred but I can't remember why.

I'm sure Bellerophon, GDB and/or VC10 will help us out shortly.
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 4:37 pm

Being a turbo jet with a relatively small diameter compressor [unlike modern big fan engines where you have to pause to allow the big fan to catch up] the Olympus could accelerate to take off power very quickly and any odd problems were catered for by the the electric throttle control system along with the primary nozzle which could alter the speed of the LP compressor compared to that of the HP compressor so overcoming any engine acceleration problems.

As Concorde was a noisy aircraft noise abatement proceedures had to carefully planned and as part of this the predictable and fast acceleration of the engines was built into the proceedures, in that if the electric throttle system was allowed to do this then the time taken for the engines to get to T/off power could be predicted whereas if the pilots opened them slowly the time was unpredictable. Therefore to allow the electric control system to control the engine acceleration, the throttles where advanced by the pilots at a faster rate than the control system would open them.

The metal vanes in front of the compressor blades were supports for the the engine shaft front bearings

Hope that helps

littlevc10
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 6:42 pm



Quoting VC10 (Reply 2):
Hope that helps

It certainly does.

Thanks for taking the time to write a good detailed description.

 thumbsup 
 
vikkyvik
Posts: 11768
Joined: Thu Jul 31, 2003 1:58 pm

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 7:49 pm



Quoting VC10 (Reply 2):
Being a turbo jet with a relatively small diameter compressor [unlike modern big fan engines where you have to pause to allow the big fan to catch up] the Olympus could accelerate to take off power very quickly and any odd problems were catered for by the the electric throttle control system along with the primary nozzle which could alter the speed of the LP compressor compared to that of the HP compressor so overcoming any engine acceleration problems.

Sort-of-related question:

Given that Concorde had an electronic throttle control, why did it also have a flight engineer? Seems that in modern airplanes, electronic engine controls have largely replaced FE's in the cockpit.

Just wondering. Thanks....
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
ANITIX87
Posts: 2952
Joined: Mon Mar 07, 2005 4:52 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 7:56 pm



Quoting Vikkyvik (Reply 4):
Given that Concorde had an electronic throttle control, why did it also have a flight engineer? Seems that in modern airplanes, electronic engine controls have largely replaced FE's in the cockpit.

This, however, wasn't the only reason for having an FE. If you watch the video posted by the OP (which is amazing, btw), you'll see that the FE is responsible for ensuring the positioning of the intakes, for moving the center of gravity, and for various other small tasks that a computer could do but that must be guaranteed in order for Concorde to fly safely. The FE was a redundant system of sorts, but his role was crucial in order to allow the pilots to focus on their respective tasks.

TIS
www.stellaryear.com: Canon EOS 50D, Canon EOS 5DMkII, Sigma 50mm 1.4, Canon 24-70 2.8L II, Canon 100mm 2.8L, Canon 100-4
 
vikkyvik
Posts: 11768
Joined: Thu Jul 31, 2003 1:58 pm

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 7:58 pm



Quoting ANITIX87 (Reply 5):
This, however, wasn't the only reason for having an FE. If you watch the video posted by the OP (which is amazing, btw), you'll see that the FE is responsible for ensuring the positioning of the intakes, for moving the center of gravity, and for various other small tasks that a computer could do but that must be guaranteed in order for Concorde to fly safely. The FE was a redundant system of sorts, but his role was crucial in order to allow the pilots to focus on their respective tasks.

Cool, thanks for the response.

I figured there was a good reason for having the FE's. Just didn't know exactly what it was.

Can't watch the videos at work, unfortunately.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 8:00 pm



Quoting Vikkyvik (Reply 4):
why did it also have a flight engineer? Seems that in modern airplanes, electronic engine controls have largely replaced FE's in the cockpit.

It wasn't electronic in the modern "glass-cockpit" sense. It may have had an analogue FBW system, computer-controlled thrust and digital intake computers but there were still a lot of systems to monitor with "steam gauges", especially compared to contemporary airliners.
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 8:29 pm



Quoting ANITIX87 (Reply 5):
The FE was a redundant system of sorts, but his role was crucial in order to allow the pilots to focus on their respective tasks.

I do not think you will find anybody who knows anything about the Concorde operation would agree with your statement as Concorde took 3 people to operate it and the F/E was not an add on he was as necessary as the other two.

Just to point out the intakes under normal conditions worked automatically and only under failure conditions did the F/E operate them manually. In fact to get the intakes to work automatically was one of the marvels of the design.

There were if I remember correctly 197 emergency/abnormal drills which included the 14 memory drills and all these drills were operated by the F/E, on top of his normal duties. He was not only expected to operate these procedures but also to understand the technical background to them so as to interpret their correct operation

Electric throttles did not kill off the F/E but rather the huge increase in computer capacity, the improvement in system design and reliability and the vast improvement in communications, which allow the crew to ask base immediately for technical advice

Anyway that is all history now , but was great fun whilst it lasted Big grin

littlevc10
 
ANITIX87
Posts: 2952
Joined: Mon Mar 07, 2005 4:52 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 8:45 pm



Quoting VC10 (Reply 8):
I do not think you will find anybody who knows anything about the Concorde operation would agree with your statement as Concorde took 3 people to operate it and the F/E was not an add on he was as necessary as the other two.

I didn't mean he was unnecessary compares to the pilot. I meant he was there as a redundant system for the aircraft's computers. As you said, the FE was very important to Concorde's safe operation, especially in case something went awry.

TIS
www.stellaryear.com: Canon EOS 50D, Canon EOS 5DMkII, Sigma 50mm 1.4, Canon 24-70 2.8L II, Canon 100mm 2.8L, Canon 100-4
 
User avatar
moo
Posts: 4033
Joined: Sun May 13, 2007 2:27 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 10:10 pm



Quoting SpeedBirdA380 (Thread starter):
The second question is this. What doe's the metal "guard" in front of the fanblades of this Concorde engine do? I have also seen them on other aircraft engines too.



Quoting VC10 (Reply 2):
The metal vanes in front of the compressor blades were supports for the the engine shaft front bearings

They were also guide vanes to clean up the airflow through the engine - you can see another set behind the front fan.

I have one in my living room  Smile
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Wed Jan 21, 2009 11:14 pm

SpeedbirdA380,

Most commercial engines spool up slowly for a number of reasons most notably the fact that for safety and simplicity reasons: Most civilian-engines fuel-control systems operate with a wider surge-margin. Safer it may be, and simpler than the alternatives, it produces a slower spool-up rate. Military (particularly fighter-jet and high performance aircraft engines) engines often use a fuel-control system which is geared to operate with a smaller surge-margin which allows a faster spool-up rate. To compensate for the closer surge-margin, more bleed valves are usually fitted to the engine (possibly, different scheduling on guide-vanes, and a more precise electronic fuel control system) to allow the pilot to rapidly move the throttles around without having to seriously worry about stalls and surges.

Other factors that play a role in spool-up rate has to do with
- The fact that some engines are naturally more surge-resistant than others which usually allows a faster spool-up rate
- The weight or weights of the shaft(s). The heavier the shaft is, generally the slower they respond. When you have twin-spool jets you have sometimes a case where one shaft responds behind the other.

The engine from which the RR Olympus Mk.593 (and later 610 model) was a derivative of, was the engine to power the TSR.2 which was a military, high-performance twin-engined strike plane the British were developing during the 1950's and 1960's which was largely cancelled for political reasons. Being a military design, it was built to have good aerodynamics: Stall and surge resistance (though technically it had a bunch of problems early on, but they were eventually fixed to the best of my knowledge), and reasonably quick responsiveness. The Mk.593 was a derivative version which to the best of my knowledge was a bit more powerful, and probably had various aerodynamic refinements not to mention a few modifications to the nozzles to reduce noise-levels a bit, but was still quite responsive, had good stall and surge resistance and such.

As other members noted, the Concorde utilizes an Electronic Fuel Control system which is basically a Fly-By Wire for engines, and as David L basically stated interpreted the throttle movements and took care of the small details. This essentially maximizes the performance and responsiveness of the engine while minimizing the odds of a surge occurring (not that the Mk 593 was not a surge resistant engine to begin with).

The Mk.610 by the way more or less was a version with an annular combustion chamber -- the 593 used a can-annular system which is not as efficient.


One interesting thing to note about the Concorde's throttles is that unlike most afterburning engines, where you push the throttles up to full power, and once you continue pushing the burners kick on -- Concorde's throttles work pretty normally up to the max-thrust point.

When the pilot want burners, there are four buttons which kind of look like the buttons you see on an old casette recorder. They're silver in color if I remember correctly. When those are pressed and the throttle is pushed to max the burners light (or if you push the throttles to the max power setting, then hit those buttons they light). There are at least 2 AB settings, a 20% afterburning set-up, and a Contingency setting which gives full burner which is to be used in emergencies such as a dual engine failure. Contingency power setting from what I've been told is only to be used in emergencies and actually can melt part of the nozzles.


If I'm wrong in anyway, please say so.


Blackbird
 
Max Q
Posts: 5629
Joined: Wed May 09, 2001 12:40 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 7:33 am

Are the afterburner switches pushed down or pulled up to activate ?

I believe they were operated in pairs inflight to allow for a 'gentler' acceleration.

Were they ever operated inflight simultaneously and was that a really abrupt sensation.

Thanks a lot from a huge Concorde fan.
The best contribution to safety is a competent Pilot.
 
User avatar
HAWK21M
Posts: 29867
Joined: Fri Jan 05, 2001 10:05 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 8:10 am



Quoting VC10 (Reply 8):
There were if I remember correctly 197 emergency/abnormal drills which included the 14 memory drills and all these drills were operated by the F/E, on top of his normal duties

Interesting Information.Pity the Aircraft no longer flies.But very educational never the less.Thanks.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 8:42 am

Quoting Moo (Reply 10):
They were also guide vanes to clean up the airflow through the engine - you can see another set behind the front fan.

Makes sense. I thought it might be something like that as well.

Quoting Moo (Reply 10):
I have one in my living room

:D

I would love to have some memorabilia from a real Concorde in my room.

Quoting VC10 (Reply 8):
Anyway that is all history now , but was great fun whilst it lasted

  

Quoting Blackbird (Reply 11):
Blackbird
Reply 11,

Thanks very much. Great stuff.


Glad some of you liked the videos. You probably found the other video's but in case you didn't here are some more from the same flight.


Concorde Acceleration 0.90 mach to 1.7 mach
http://uk.youtube.com/watch?v=KX9Wf87ShIE

Concorde Descent and Landing in JFK
http://uk.youtube.com/watch?v=JL4cT05Ctck

Take off from JFK
http://uk.youtube.com/watch?v=LRbKs3C_l-Y

[Edited 2009-01-22 00:43:00]
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 9:52 am



Quoting Blackbird (Reply 11):
When the pilot want burners, there are four buttons which kind of look like the buttons you see on an old casette recorder. They're silver in color if I remember correctly. When those are pressed and the throttle is pushed to max the burners light (or if you push the throttles to the max power setting, then hit those buttons they light). There are at least 2 AB settings, a 20% afterburning set-up, and a Contingency setting which gives full burner which is to be used in emergencies such as a dual engine failure. Contingency power setting from what I've been told is only to be used in emergencies and actually can melt part of the nozzles.

The 4 reheat switches are selected up for reheat and for the take -off they were all pre selected to the reheat position so that as the engine accelerated the reheat would automatically ignite when egine conditions were correct [above 82% N1 seems to ring a bell]
The use of reheats increased the thrust by about 20% but the engine used approximately double the fuel flow to achieve this. 23,000 kgs per hour per engine I seem to remember
was a good ball park figure, so it was lucky that we only used reheat for about 60 seconds or so

For power loss emergencies during take-off [such as any single engine failure] as the failed engine wound down contingency power would automatically be selected on the other engines, or contingency could be manually selected by further upward selection on the reheat switches. Contingency power increaased the speed of the engine and so as reheat fuel flow was a % of dry engine fuel flow the reheat fuel increased as well.

Although an emergency power setting and the crew had to record every use of Contingency power as it did affect the TBO to say that there was a fear of it melting the nozzles is a bit extreme

Quoting Max Q (Reply 12):
I believe they were operated in pairs inflight to allow for a 'gentler' acceleration.

The maximum power that could be achieved with the throttles fully open depende on what power rating was selected, ie Take off, climb , cruise so for supersonic acceleration
"Climb rating" would be selected and the throttles were slowly advanced to their stops, at which point the reheats were selected in pairs so as not to spill the champagne  Big grin and there was a nudge, but to be honest at heavy weights it was hardly noticeable. However at light weights like when we did round the bay charters the nudge was very noticeable and the passengers loved it and the performance was exciting too. On one charter by mistake
[ and that is another story] all four reheats were selected at the same time and the old girl really lived up to her name of pocket rocket.


SpeedBirdA380,

Just as a matter of interest the F/E in your sequence of videos was the longest serving flight crew member on Concorde as he started his course in 1975 and retired off the old girl in 1999 some 24 years

littlevc10  cloudnine 
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 10:16 am



Quoting VC10 (Reply 15):
Just as a matter of interest the F/E in your sequence of videos was the longest serving flight crew member on Concorde as he started his course in 1975 and retired off the old girl in 1999 some 24 years

Very interesting. He must have loved his flying. This is also a guess but the Captain refers to the pilot flying in the right hand seat as Les. Is that the famous Les Brodie?

Quoting VC10 (Reply 15):
However at light weights like when we did round the bay charters the nudge was very noticeable and the passengers loved it and the performance was exciting too.

So were you are F/E on the old bird too?  Wow!
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 10:37 am

Yes the co-pilot in this video was Les Brodie during his first stint on Concorde when he was a young man.He left to get his command on another aircraft and after a few years came back as a captain on Concorde. In answer to your second question yes I was, retiring off the old girl in 1998 which is hard to believe is now some 10 years ago .

littlevc10
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 10:46 am

Quoting VC10 (Reply 17):
In answer to your second question yes I was, retiring off the old girl in 1998 which is hard to believe is now some 10 years ago .

Fantastic. Thanks for your imput to this thread.

And yes I know it's a bit of an old cliche but time really doe's fly. - No pun intended. 

I cant believe roughly 5 and a half years has passed since she retired.

[Edited 2009-01-22 02:47:16]

[Edited 2009-01-22 02:47:45]
 
zarniwoop
Posts: 255
Joined: Wed Apr 27, 2005 11:43 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 11:38 am

If you have an interest in Concorde I would recommend buying the DVD that the youtube clip was taken from. It goes into lots of detail and is about 4hrs long, so value for money.
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 11:56 am



Quoting VC10 (Reply 15):
at which point the reheats were selected in pairs so as not to spill the champagne Big grin and there was a nudge, but to be honest at heavy weights it was hardly noticeable.

On a couple of my flights there were people who were disappointed not to feel the nudges, even after the warning from up front. If you were leaning forwards or moving even slightly in your seat, I suspect you wouldn't notice them. I, on the other hand, was utterly focussed and never missed them.  Smile
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 1:34 pm



Quoting Zarniwoop (Reply 19):
If you have an interest in Concorde I would recommend buying the DVD that the youtube clip was taken from. It goes into lots of detail and is about 4hrs long, so value for money.

Yes I think I will. I did not realise you could get this but of course, this is a ITVV production. I already have a few of their DVD's of the 747-400 series,dont know how I missed this one over the years.  boggled 

I never got the chance(well finance to be honest) to fly in her so DVD's like this are great.
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Thu Jan 22, 2009 11:07 pm

VC-10,

The afterburners engage at only 82% N1? What's the the typical N1/N2 settings for takeoff?

How much of an increase in RPM is produced when contingency power is engaged?


BTW: Sorry about the comment about the nozzles melting, someone told me that.
 
Max Q
Posts: 5629
Joined: Wed May 09, 2001 12:40 pm

RE: Concorde Questions(throttles And Engines)

Fri Jan 23, 2009 3:58 am

Thanks for the very informative and interesting information VC10, I wondered about the reheat switches and thought it might be possible to 'accidentally' select them if they were activated by pushing down !

Incidentally, did you fly the VC10 as well ? another one of my all time favourite aircraft. I remember flying on them from London to Hong Kong with numerous stops in the 70's.

A stop in Rangoon was particularly memorable, flying was truly an adventure back then.
The best contribution to safety is a competent Pilot.
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Fri Jan 23, 2009 2:01 pm

Blackbird,

The actual requirements for Reheat were as follows

1] Reheat or Contingency selected
2] N1 greater than 81% [ I was wrong by 1% never trust memory too much]
3] The throttles more than 10% open [ this was for the reject t/off conditions when you
[ did not want reheat with reverves power, NOW
that would burn out the secondary nozzles]

As you can appreciate it is difficult to remember actual engine figures 10 years after retirement,
and rather than give some figures from distant memory which could be wrong and misleading I can give you the limits and normal figures would have been some what less

N2 . N1 . EGT . Time

Contingency . 106.8 % 102 % 833 2.5 minutes
Take Off . 105.7 % 102 % 806 5 minutes




Max Q

Yes I was an all British aeroplane boy [well a bit of French to] with VC-10 and
Bristol Britannia on my licence which meant I could go any where in the world and be unemployed. The VC-10 was definately used as the equivalent to the stopping train as we very rarely went any where non stop unlike the flash B707 which went one long sector and stopped
It was quite normal on the VC-10 crews to do 3 sectors 12.5 hours duty days with a single crew,
All good fun though and a lovely aircraft, but glad I was young when I did it.

littlevc10 Big grin
 
ex52tech
Posts: 553
Joined: Wed Dec 06, 2006 2:28 pm

RE: Concorde Questions(throttles And Engines)

Fri Jan 23, 2009 8:33 pm

Great info. on a beautiful airplane guys. Thanks.

Wish I could have worked on Concorde, and it's engines.  crying 
"Saddest thing I ever witnessed....an airplane being scrapped"
 
Max Q
Posts: 5629
Joined: Wed May 09, 2001 12:40 pm

RE: Concorde Questions(throttles And Engines)

Sat Jan 24, 2009 5:26 am

VC10,

You certainly flew some classic and unique British Aircraft, I am somewhat familiar with the 'Whispering Giant' myself as my father flew it in the RAF.

Post war aviation development up to the introduction of Concorde and the 747 was, in my opinion the most fascinating and interesting era a Professional Pilot could be involved in and I couldn't think of a finer way to cap that than with flying the Concorde itself.

Those were the days you could look up to watch an Aircraft fly overhead and immediately know what it was as each type was so distinctive.

Not to knock modern Airliners as their capabilitys are truly impressive but they all seem a bit sterile and boring these days, another 'big twin' they lack the character of earlier machines !

Thanks for your very interesting and informative posts.
The best contribution to safety is a competent Pilot.
 
SpeedBirdA380
Topic Author
Posts: 335
Joined: Sat Jul 26, 2008 9:57 pm

RE: Concorde Questions(throttles And Engines)

Sat Jan 24, 2009 10:08 am



Quoting Max Q (Reply 26):
Post war aviation development up to the introduction of Concorde and the 747 was, in my opinion the most fascinating and interesting era a Professional Pilot could be involved in and I couldn't think of a finer way to cap that than with flying the Concorde itself.

Yes MaxQ,I totally agree with you.

It must have been a wonderful time to have been an aviator. Especially since flying was not available to the masses and was rather expensive so it must have been a great privilige to have been a part of a flight crew that got to fly these amazing new jets and travel the world at the same time.

What an adventure it must have been to visit all those places with some being I imagine, virtually untouched by tourism.

Must of been a blast!
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Questions(throttles And Engines)

Sat Jan 24, 2009 11:46 am



Quoting Max Q (Reply 26):
I am somewhat familiar with the 'Whispering Giant' myself as my father flew it in the RAF.

Perhaps he flew me. I flew in a few RAF Britannias in the '60s.  Smile

Yup, my favourite aircraft, too: Britannia and VC-10 because I spent so much time in them in my early years, and Concorde, for obvious reasons. I'd add the CV-880 because it was my first jet but this is not the time.  Smile
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Sat Jan 24, 2009 9:01 pm

VC-10,

Quote:
Contingency . 106.8 % 102 % 833 2.5 minutes
Take Off . 105.7 % 102 % 806 5 minutes

I thought 100% was the maximum safe RPM...
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Concorde Questions(throttles And Engines)

Sat Jan 24, 2009 10:18 pm



Quoting Blackbird (Reply 29):

I thought 100% was the maximum safe RPM...

Many engines are like that...100% is somewhat arbitrary, since the actual thrust is primarily a function of N1 speed, not N1 %. Some designs normalize it all to be 100% = maximum thrust for that mode, some just assign 100% = a particular RPM, some pick 100% = maximum rated thrust.

Tom.
 
JAGflyer
Posts: 3453
Joined: Tue Aug 10, 2004 5:31 am

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 4:33 am

These "Nitrocharger" featuring the Concorde are very interesting, thanks for making us aware of them.

Why do they retard the throttles substantially (after the 2nd countdown)?
Support the beer and soda can industry, your recycle old airplanes!
 
User avatar
Starlionblue
Posts: 17058
Joined: Fri Feb 27, 2004 9:54 pm

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 5:54 am



Quoting Tdscanuck (Reply 30):
Many engines are like that...100% is somewhat arbitrary, since the actual thrust is primarily a function of N1 speed, not N1 %. Some designs normalize it all to be 100% = maximum thrust for that mode, some just assign 100% = a particular RPM, some pick 100% = maximum rated thrust.

For example, the Space Shuttle Main Engines go to 104.5% of thrust during take off. During emergencies, they can go to 109%, although failure probability increases significantly over 104.5%. The 100% figure is simply the thrust level from the original requirement. During testing, it was found that the engines could operate safely beyond "100%"
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 11:47 am



Quoting JAGflyer (Reply 31):
Why do they retard the throttles substantially (after the 2nd countdown)?

"3-2-1-noise" is the noise abatement initiation and at the noise call the F/E switches off the Reheats and retards the throttles to a setting pre-set before the take off. Once the noise listening point has been passed climb power is gently restored. The video shows a LHR departure which is reasonably simple,however on a 31L departure out of JFK the engines would be throttled restored then throttled again so as to comply with noise requirements and minimum height required by the departure procedure.

From places where there was no noise abatement procedure [such as Barbados where you went out over the sea] then the the reheats were switched off at 500ft and the engine ratings were selected to CLIMB at 1000 ft with the throttles never being moved.

littlevc10
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 4:21 pm

VC-10


I have some questions...

1.) Does 100% N1 or N2 with burners equate to 38,030 lbf or 38,050 lbf? Or does 105.7% N1/102% N2 + 20% Burner = 38,030 lbf or 38,050 lbf (I've heard both figures)?

2.) What RPM's are used during supersonic cruise (from M=1.7 to M=2.04)

3.) While I'm at it, how much thrust does 81% N1 yield (with or without afterburner)?

4.) Also, with contingency power set how much thrust does the engine produce would you say?


Blackbird
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 5:07 pm



Quoting Blackbird (Reply 34):
1.) Does 100% N1 or N2 with burners equate to 38,030 lbf or 38,050 lbf? Or does 105.7% N1/102% N2 + 20% Burner = 38,030 lbf or 38,050 lbf (I've heard both figures)?

Almost certainly neither. Max rated thrust is usually measured on a test stand with a bell mouth inlet (it's essentially impossible to accurately measure true thrust in flight). As soon as you install it in a real nacelle with a real inlet, and start giving it some airspeed, it all changes.

Tom.
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Sun Jan 25, 2009 5:33 pm



Quoting Blackbird (Reply 34):
.) Does 100% N1 or N2 with burners equate to 38,030 lbf or 38,050 lbf? Or does 105.7% N1/102% N2 + 20% Burner = 38,030 lbf or 38,050 lbf (I've heard both figures)?

Well to start with I only ever used the term 38,000 lbs of thrust the odd 10s are hardly worth the worry to an operating crew.

The engine is rated at 38,000 lbs of thrust {including reheat} at sea level at 15 deg C

The max N2/ N1 are the max structural limits for those parameters, but in day to day operation the N2 and N1 will vary according to the conditions of the day and those expected N2 and N1 speeds will be worked out prior to take off so the crew can check whether the engine is working correctly. Basically on a cold day the rotational speeds will be quite low for take off and on a hot day they will be quite high but never exceeding the limit

100% power equals 38000 lbs but the N2/N1 required to get that depends on the conditions of the day

Quoting Blackbird (Reply 34):
While I'm at it, how much thrust does 81% N1 yield (with or without afterburner)?

No information on that,but from the VC-10 aircraft using R/R Conway engines and a max N2 of about 103%,then 85%N2 equated to about 50% of max power the other 50% coming from the next 18% increase in N2, so I imagine the Concorde's engines would be similar

As to the other questionswell as I have said before I am sorry but with 10 years having passed and then another airraft under my belt actual day to day figures I cannot remember , but I can give you the Max figures allowed

Climb/Cruise------N2 105.3------N1----102 ,and Max EGT varied with total air temp

I always feel if I do not know the actual figures it is better to say nothing than guess

Sorry I cannot be of more help

littlevc10
 
User avatar
cpd
Posts: 4551
Joined: Sat Jun 28, 2008 4:46 am

RE: Concorde Questions(throttles And Engines)

Mon Jan 26, 2009 2:07 am

Quoting David L (Reply 1):
I seem to recall that the swift movement from idle to take-off power wasn't just possible, it was preferred but I can't remember why.

Wasn't that the take-off power selection. Taking the throttles and advancing them very rapidly forward. It didn't speed up the engines necessarily that quickly - but it was interpreted as requiring take off power. In other situations, (like autoland), advancing 2 or more throttles all the way forward would do other things like commencing a go-around.

Quoting ANITIX87 (Reply 9):
I didn't mean he was unnecessary compares to the pilot. I meant he was there as a redundant system for the aircraft's computers. As you said, the FE was very important to Concorde's safe operation, especially in case something went awry.

The FE was essential. I couldn't imagine it being operated by only two people. If you were to watch the ITVV 2-DVD set (which these videos were ripped from), you'd see exactly how much Roger Bricknell does. He's pretty busy. And there is no scope for it to be done by two people. Nowadays, if the plane had been upgraded to a digital flight deck, there might have been scope to automate a lot of the procedures done by the FE.

Quoting SpeedBirdA380 (Reply 16):

Les Brodie, Flight Engineer Roger Bricknell (who was the most senior flight engineer at the time) and Captain David Rowland. They did a superb job presenting on this video. The Canarsie Climb on the 2nd DVD is worth watching.

Quoting Max Q (Reply 26):
Not to knock modern Airliners as their capabilitys are truly impressive but they all seem a bit sterile and boring these days, another 'big twin' they lack the character of earlier machines !

Bravo, bravo! I love the older planes.  Smile

[Edited 2009-01-25 18:12:54]
 
Max Q
Posts: 5629
Joined: Wed May 09, 2001 12:40 pm

RE: Concorde Questions(throttles And Engines)

Mon Jan 26, 2009 5:06 am

It's very possible David L, love that Convair 880 as well, another great machine from a golden age !


Happy landings,

Max
The best contribution to safety is a competent Pilot.
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Mon Jan 26, 2009 4:05 pm



Quoting Cpd (Reply 37):
who was the most senior flight engineer at the time

No he was not the most senior I am afraid, but very near it.

littlevc10
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Mon Jan 26, 2009 5:00 pm

VC-10,

Not to sound stupid, but it invariably will... I'm just wondering... if you have cold weather, why do you use a lower RPM? I figure you guys would want to milk it for all it was worth.
 
vikkyvik
Posts: 11768
Joined: Thu Jul 31, 2003 1:58 pm

RE: Concorde Questions(throttles And Engines)

Mon Jan 26, 2009 6:59 pm



Quoting Blackbird (Reply 40):
Not to sound stupid, but it invariably will... I'm just wondering... if you have cold weather, why do you use a lower RPM? I figure you guys would want to milk it for all it was worth.

I'm assuming due to the air being more dense on a colder day = less RPM required to generate takeoff thrust.

Correct me if I'm wrong, though.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 12:39 am

Vikkyvik,

Yeah, but I'd figure you'd want to get your money's worth and use full power anyway as you'd get more bang for your buck.


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

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 12:48 am



Quoting Blackbird (Reply 42):
Yeah, but I'd figure you'd want to get your money's worth and use full power anyway as you'd get more bang for your buck.

... or more bucks for your bang. After a shaky start, Concorde was expected to make money or have the plug pulled.

How much of a difference would it have made to the overall performance of a transatlantic flight, for example, especially considering that noise-abatement procedures began 90 seconds after take-off?
 
User avatar
cpd
Posts: 4551
Joined: Sat Jun 28, 2008 4:46 am

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 1:54 am

Quoting Blackbird (Reply 40):
VC-10,

Not to sound stupid, but it invariably will... I'm just wondering... if you have cold weather, why do you use a lower RPM? I figure you guys would want to milk it for all it was worth.

From my limited knowledge, it's to do with the extra power not being needed to achieve the same performance.

It's a set of four rocker switches on the overhead panel (climb / cruise power settings). Part of the normal procedures. In some conditions, there is said to be no change at all in the RPM.

It'll most likely have effect around the equator where the temperatures at higher altitude are very cold. I never thought these reductions applied on takeoff (apart from the engine no.4 88% reduction). The reductions being hinted at above are done at the corner point between climb and cruise (FL490/FL500 and M2.0) if I remember right.

If you were to buy the ITVV Concorde DVD set, you'll get a good explanation of what this is all about from Roger Bricknell. Sadly, they have pretty ordinary weather on the route, so there is no effect at all when the rating is changed.

Quoting David L (Reply 43):

How much of a difference would it have made to the overall performance of a transatlantic flight, for example, especially considering that noise-abatement procedures began 90 seconds after take-off?

However, the RNA procedures save time don't they - so they would balance out the noise-abatement procedures on takeoff? And the anti-noise procedures are generally waved at some modest distance away from the airport where dispensation is given to surpass 250kias (so the plane is free to climb at VMO up to FL270 or FL290). Correct me if I'm wrong.

I'd imagine they wouldn't save much time waving the noise-abatement procedures.

Quoting Vc10 (Reply 39):
No he was not the most senior I am afraid, but very near it.

Thanks for the correction.  

[Edited 2009-01-26 17:57:59]

[Edited 2009-01-26 18:02:06]

[Edited 2009-01-26 18:04:33]
 
vikkyvik
Posts: 11768
Joined: Thu Jul 31, 2003 1:58 pm

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 7:35 am



Quoting Blackbird (Reply 42):
Yeah, but I'd figure you'd want to get your money's worth and use full power anyway as you'd get more bang for your buck.

Can't say I understand what you mean. If you can have the same performance (or enough performance, as the case may be) with less wear on the engines (lower RPM's), why wouldn't you do that?

Similar to derates for "normal" airliners. If you don't need the extra thrust on a particular takeoff, then why use it? It'd just waste fuel and contribute more engine wear.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
vc10
Posts: 1339
Joined: Thu Nov 15, 2001 4:13 am

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 11:45 am

I think you are all missing the point an engine at full throttle operates to a limiting parameter and we will say at full throttle for take-off the limiting parameters could be

Max N2---Max N1--Max EGT or Max pressure within the engine[ P3] which is the output pressure from the HP compressor There are more sophisticated limiters too but these will do for demonstration

Now for example at high OAT the engine max RPM will be limited by the EGT limiter

At low OAT because of the higher density of the air the Max[ P3] pressure will achieved at a lower RPM and so the engine RPM will be limited so as not to exceed that max P3 and similar with the Max EGT

So for any given take off the expected N2 , N1 are calculated before the roll begins and takes into account the conditions for THAT day. When the engine has stabilized at that days maximum power then the parameters are checked to see that they meet or exceed the pre calculated figure and also that they do not exceed the maximum parameters.

There was no graduated power take offs on Concorde , you just opened the throttles fully and checked that you got the correct power setting for that day's conditions

litlevc10
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 1:44 pm



Quoting Vc10 (Reply 46):
I think you are all missing the point

In my case that's always possible, however...

Quoting Vc10 (Reply 46):

At low OAT because of the higher density of the air the Max[ P3] pressure will achieved at a lower RPM and so the engine RPM will be limited so as not to exceed that max P3 and similar with the Max EGT

I assumed Blackbird was talking about allowing those limits to be busted "for effect" and not worrying about excessive wear and tear or minor damage. Of course, I've no idea what damage would occur. I was just making the point that, for most of its career, Concorde wasn't treated as a bottomless pit down which to pour limitless maintenance resources just for effect.  Smile

Quoting Cpd (Reply 44):
However, the RNA procedures save time don't they - so they would balance out the noise-abatement procedures on takeoff?

I don't think Blackbird was looking for balance. I think she was talking about "pulling out the stops".
 
vikkyvik
Posts: 11768
Joined: Thu Jul 31, 2003 1:58 pm

RE: Concorde Questions(throttles And Engines)

Tue Jan 27, 2009 4:37 pm



Quoting Vc10 (Reply 46):
I think you are all missing the point an engine at full throttle operates to a limiting parameter and we will say at full throttle for take-off the limiting parameters could be

Gotcha. That's what I thought you were originally stating. I guess my 2nd reply probably wasn't really a propos.

Quoting David L (Reply 47):
I assumed Blackbird was talking about allowing those limits to be busted "for effect" and not worrying about excessive wear and tear or minor damage. Of course, I've no idea what damage would occur. I was just making the point that, for most of its career, Concorde wasn't treated as a bottomless pit down which to pour limitless maintenance resources just for effect.

That's what I thought Blackbird was talking about too.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".

Who is online

Users browsing this forum: Bing [Bot] and 10 guests