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-   -   Concorde question (https://www.pprune.org/tech-log/423988-concorde-question.html)

Hapsen 24th Jan 2014 19:54

Great thread - and it inspired me to buy Ted Talbot's book.

I used to work with a design engineer who worked on the intake controls team - many an hour at work was spent listening to his stories!

But back to the thread....

In T. Talbot's book he mentions that above Mach 1.6 (?) Concorde was certified as a twin-engined aircraft due to the common intake.
As I don't know how in those days the equivalent of ETOPS was - how were the diversion airfields worked out? As today (say) ETOPS 180 is somewhat different if you're at Mach 0.83 or 2.02 :-)

Thanks!

Shaggy Sheep Driver 19th Feb 2014 11:26

Static ports
 
I've noticed static ports under the fuselage at the back, between the engines. Are these just additional ports for the aircraft's general static pressure measurement system, or do they have a specific function?

ruddman 19th Feb 2014 17:03

Here's a question or three from a non-pilot:

Evidently most modern airliners use around 3 x height plus whatever to slow on approach etc.

1. Being that the Concorde looks like a slippery sob, how were the descents planned?

2. Did you just pull the throttles back to flight idle?

3. Or was there a little more engine management and more gradual handling of the engines and descent?

4. And I'm guessing the approach speeds were fairly high so hitting the touchdown zone was pretty important?

5. So if things got out of shape a little, and a G/A was required, how do you handle what looks like 4 rockets on the wings and applying the right amount of power?





Ok, more then 3 questions sorry. :O

Simple questions I'm sure but since I'm probably never going to able to fly one myself, getting these questions answered will allow me to sleep again at night. :p

CliveL 20th Feb 2014 07:09

Static ports

SSD

I'm afraid I can't tell you what they actually do, but I am pretty sure they aren't part of the anemometry because those static ports are "pepperpots" mounted on specially machined and jigged flat plates. This was necessary because static pressure at Mach 2 is sensitive to local skin waviness.

Do you have a photo?

Shaggy Sheep Driver 20th Feb 2014 08:54

Thanks Clive, I did wonder why the static ports near the doors used those plates.

I'll look for a photo. If I can't find one, I'll take one next time I'm with G-BOAC (next week).

There are others as well, as in the pictures below (but these are not the ones I'm referring to):

https://www.google.co.uk/search?q=co...%3B3912%3B2599

Linktrained 20th Feb 2014 16:40

Concorde Descent.
Further to ruddman's 1, 2 & 3 ( above)


After a small number of years of operating, there was a press report that AF had altered their descent on NY - Paris, which allowed them to carry 2 more passengers ( high revenue). Does anyone recall what this was ?

Bellerophon 22nd Feb 2014 00:48

Shaggy Sheep Driver

...I've noticed static ports under the fuselage at the back, between the engines. Are these just additional ports for the aircraft's general static pressure measurement system, or do they have a specific function?...

I'm not the right person to be answering this, and the reference diagram I'm looking at, whilst very detailed, is not particularly clear - at least to a pilot!

However, from your description, I wonder if they might possibly be the two pressurisation static ports that are located in that area?

Bellerophon 22nd Feb 2014 02:16

ruddman


...Being that the Concorde looks like a slippery sob, how were the descents planned?...

The distance required to decel/descend from M2.0 in cruise/climb down to 3,000 at 250 kts was obtained from a checklist chart. Entering with the (expected) FL at Top of Descent and then correcting for the average wind component expected in the descent and also for the temperature deviation from ISA gave the required track miles. It wasn’t used a lot, because generally the more critical descent requirement was to decelerate so as to be (just) below M1.0 at a specified point on the arrival route, for noise reasons, to avoid booming land.

There was a second chart, utilised in the same way as the first, which provided this information. Sometimes this distance might need to be increased a little, as, if a subsonic cruise was expected before continuing the approach, the engines were “warmed” up at M0.97 and after passing FL410, by the application of power, for one minute, by the Flight Engineer.



...Did you just pull the throttles back to flight idle?...

Only if you were willing to run the risk four pop surges from the engines and the near certainty of a clip round the ear from your Flight Engineer.

Usually the pilots handled the throttles from “Power Up to Gear Up” and from “Gear Down to Shut Down”. The Flight Engineer generally did all the rest, which, thankfully, left all the tricky drills and procedures as his responsibility.



...Or was there a little more engine management and more gradual handling of the engines and descent?...

On a normal decel/descent, the handling pilot would select ALT HOLD and then ask the Flight Engineer to reduce power to 18º TLA (Throttle Lever Angle). The speed would decay to 350 kts IAS (Indicated Air Speed) IAS HOLD was engaged and the descent flown at 350 kts IAS. The next power reduction (32º TLA) came when, still flying at 350 kts IAS, the Mach number reduced through M1.50.


...And I'm guessing the approach speeds were fairly high so hitting the touchdown zone was pretty important?...

In terms of not running off the end of the runway, touching down in the correct spot was as important on Concorde as on other aircraft types.

However, due to the geometry of Concorde on landing, the tail, engine pods and reverser buckets were already fairly close to the runway. Add in a “firm” touchdown, or if the wings are not completely level, and ground clearance becomes marginal, so a prolonged flare and floated landing, with an increasing aircraft attitude, was not acceptable. The risk of a pod, tail or a reverser bucket scrape on Concorde was greater than on most conventional jet aircraft.



... So if things got out of shape a little, and a G/A was required, how do you handle what looks like 4 rockets on the wings and applying the right amount of power?...
  • Disconnect the autothrottles.
  • Apply FULL power without reheat.
  • Rotate to 15º and level the wings.
  • Check for Positive Climb then call for the Gear Up.
  • Maintain 15º and accelerate (you will accelerate!)
  • Passing around 210 kts, reduce power to 95% N2.
  • Approaching 250 kts, engage Autothrottles for 250 kts
  • Reduce Pitch Attitude, aiming to achieve 2,000 fpm RoC.
  • Do not miss the level off altitude for the GA profile.

Shaggy Sheep Driver 22nd Feb 2014 09:09

Thanks Bellerophon. Here's a picture:

http://i18.photobucket.com/albums/b1...ps04423a50.jpg

EXWOK 22nd Feb 2014 10:14

For the AICUs perhaps?

Bellerophon 22nd Feb 2014 11:30

Shaggy Sheep Driver

S14 and S15 decode as "Pressurisation Static Ports".

Anything more than that and I'm afraid I'm out of my depth, so you'll need one of our resident engineer experts to chip in. The one I'm thinking of might be at sea at the moment!


Here's the page from the Flying Manual:

Concorde Static Ports S14 and S15


http://i303.photobucket.com/albums/n...aticPlates.jpg

CliveL 22nd Feb 2014 12:04

SSD

I know they aren't anything to do with AICUs but seeing where they are located and looking at Bellerephon's diagram I would think they are reference static ports for the air conditioning system - needed to monitor differential pressure.

Dude where are you when we need you?

ruddman 22nd Feb 2014 19:00

Bellerophon?
 
Thank you very much sir. Appreciate it. :)

TURIN 23rd Feb 2014 11:02

By a process of elimination, as my AMM discs seem to be corrupted in CH 31 & 34, those ports could be the sense ports for the Ambient Pressure Switch & the CAU Outlet Overpressure Switch.

Shaggy Sheep Driver 23rd Feb 2014 20:29

Many thanks Bellerophon and others. It seems these ports are concerned with cabin pressurisation.

neprendo 4th Mar 2014 13:00

Hey Guys,

I'm attempting to optimise corconde wings for drag reduction as part of my thesis. My question for you is: do you know what type/name of the wing profile Concorde had.

CliveL 4th Mar 2014 16:51

Sorry Nick, you are out of luck on that one. It was tailor made to optimise cruise drag. Varied from 3% thick at the root to 1.8% near the tip, but the camber and twist don't fit any recognisable standard section.

PM me and I will send you something that might help

NHerby 5th Mar 2014 05:55

Hi,

I found on a blog a curious information. It says that in October 1964, UK wanted to leave the project. But, since the agreement signed between France and UK didn't allow any of the party to give up the project, thay stayed onboard the boat. It is the first time I hear that. Does anybody here knows if UK at some point really wanted to give up on this project? And, if this was really the case, what was the reason for this decision?

Another thing:
Earlier in this thread, Bellerophon gave a pretty good explanation of the ATC clearance for Concorde's block altitude. How did ATC managed Concorde while approaching big airports like LFPG, EGLL or KJFK? She was flying faster than any other jets, even during approach. Did the controllers had to apply specific procedures for Concorde, like bigger spearation with other planes or higher priority for landing?
Also, what was the correct pitch angle at touchdown? I guess it must be around 9 or 10 degrees but would like to know the exact figure.

roulishollandais 5th Mar 2014 08:32

Haute-couture renversante
 
@CliveL

It was tailor made
BRAVO L`ARTISTE ,MERCI :D

Shaggy Sheep Driver 5th Mar 2014 15:21

My understanding (may be wrong) is that Julian Amery (a British politician) had the 'interlocking' clause written into the Anglo-French contract because the Brits thought the French might want to pull out. Harold Wilson did want to pull ou, but couldn't because of that clause. Were the French ever prevented from pulling out by the clause?

If both parties had wanted to pull out, presumably they could have re-negotiated the contract to allow that.


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