Looking at the pic of G-BOAB in the detuner brings me to the question how they performed the run-up. No brakes, just chocks?

Club Concorde seems very bullish about its plan to moor G-BOAB in the Thames outside the London Eye. I asked around the office here (just down the river in Southwark); nearly everyone thought it was a fabulous idea.

Quax .95
Looking at the pic of G-BOAB in the detuner brings me to the question how they performed the run-up. No brakes, just chocks?

What makes you think they would not have any brakes?? When performing any engine runs always set the brakes & chock the wheels.

Just think back to the A340 that was written off in France when the brakes were released & the aircraft jumped the chocks.

tristar 500

I've got good reason for knowing that's wrong. Some time ago in the A340 discussion I said that chocks shouldn't touch the wheels but be set ahead of them by about a foot. Welllll ...... The wrath of the Eng and Tech city fathers came down on my head - until some kind soul posted the passage from the 747-400 AMM. Bingo. :ok:

tristar,
The question is less odd than it seems....
With full take-off power plus reheat, Concorde could not be held on brakes alone (hence the various procedures at take-off).

Maybe somebody has the full story.... in the light of chocks being less than perfect....

CJ

I cannot imagine any requirement for more than one engine (with or without reheat) to be run at full power when parked in the detuners. Thus there would be very little chance of exceeding the brake torque limits.

I was at Heathrow on last Sunday, 15th May; G-BOAB is still in the location detailed by Heritage Concorde. Also I can confirm that the detuner where you can see G-BOAB parked in the other picture, has now been completely demolished.

ZimmerFly said
I cannot imagine any requirement for more than one engine (with or without reheat) to be run at full power when parked in the detuners. Thus there would be very little chance of exceeding the brake torque limits.

Brake torque us only one of the things you have to think about when running at high power.

Consider running an engine on one side with all the others at idle or even shut down, what do you do when the aircraft starts to slide sideways?

The engine run drills call for "balanced" power. What this means is that you have to balance the power which means running the opposite engine at high power also.

Been there, done that!!

tristar 500

I know we seem to be straying a little off topic, but having two engines at high power against brakes set to park and all wheels chocked is going to produce a lot less torque than say a sudden stop from 30 knots at RTOW.

[I am too lazy to attempt the sums !]

:hmm:

4 years ago Spanner Turner came to my rescue on ground runs with -

Quote below is from the Maintenance Manual. (a 747 manual, but you get the picture).

C. Prepare for Engine Operation.

(1) Check that airplane is parked in clean area with wheels on areas
that are free of oil, grease, or other slippery substances.


(2) Make sure the wheel chocks are installed at the main landing gear
wheels and ground locks are installed.


(a) Do these steps if you will operate the engines for a high power
engine run.


1) Make sure that the forward wheel chock is six to twelve
inches in front of the tires.

NOTE: This will cause the thrust of the engine to be held
by the frictional force between the airplane tires and the
ground, and not the wheel chock. The wheel
chocks do not have the same frictional force as the
tires. If the tires touch the wheel chock, some of
the frictional force between the tires and the
ground is lost, and the airplane can skid. The
wheel chocks are only used to prevent the airplane
from rolling if the airplane brakes were
accidentally released before or after the engine run.

maybe not the proper place but I wanted to share this very nice and supposedly recent photo gallery on the topic...

atakacs
 

Oh wow! :ok:

Roger

Photoshop, most of it, I would say.
Still, well done.

CJ

it does say cgi if you lookhttp://images.ibsrv.net/ibsrv/res/sr...lies/wink2.gif
rod

CJ & rodlittle
 

I know, I know. :rolleyes: I saw that, but the images are just the ones you would like to have taken ............ if you wouldn't have been arrested if you'd tried to. :uhoh:

Roger.

Landroger,
What triggered my remark was merely that I don't think there's any record of a BA and AF Concorde flying in formation near to the LearJet....
But yes, we would all want to have taken photos like that.

And all of us still hope that there is a video somewhere, somehow, of one of Jean Franchi's barrel rolls.....

CJ

Firsty, i would like to say a big "hello" and "thanks" to everyone who has contributed to this fantastic record of Concorde development and Service!!

I grew up in South Oxfordshire, and on weekday mornings, at what i remember to be a bit after 11am, we would hear the "roar", and run outside into the garden to look up as she passed overhead. The most wonderful racket ! A perfect white arrow, spearing off to exotic destinations, we used to try to guess who might be aboard ;-)

Certainly one of the things that made me interested in engineering, and something to be proud of ;-)


So, here's 2 questions that i hope someone might be able to answer:


1) roughly, how many people worked on the complete development program?

and

2) How many total passenger miles did the fleet clock up over it's service life??


As someone who is now an automotive controls engineer, i have serious respect for the people who built and tested Concorde. We now take for granted being able to log and analyse data over 100's of channels at kHz rates with just a laptop and a small input conditioning box. Having been round 101 at Duxford, and seen the size and capabilites of the engineering flight recorders fitted (and the 1000's of wires linked to them) i tip my hat to anyone trying to get that all to work ;-) :ok:

Ground Running Concorde
 

I've been away 'cruising' for a few weeks (lecturing about Concorde) and thought it was time I popped back into this wonderful forum.
There were a few questions regarding ground running Concorde, so here are some 'facts' as far as I recall (Wrinkled old brain permitting).

Concorde was ALWAYS ground run in the detuners at the BA Engineering base at Heathrow, with the parking brake ON. (Save idle runs on the ramp after, say, replacing a PNC actuator etc. on departure. The required high power nozzle trim run could be deferred until the aircrafts return to LHR). Sadly I can confirm that the Concorde 'Hush House' was being demolished when I was last over the engineering patch a few weeks ago, and is probably all gone now.

The detuner chocks were like nothing else you could imagine. They were HUGE steel affairs that needed wheels to be wound down in order to move into position (took a couple of guys at least to move). Once in position forward and aft of the undercarriage, the wheels would be retracted and these 'chocks' would be tension chained together. Believe me, nothing was going to move these suckers!! :=

Engines WERE NOT run in symmetrical pairs, but the adjacent engine always was run at idle power. The reason for this was so that there was airflow over the T1 probe of the adjacent engine, a winding in this being used by the alternate engine control lane if needs meant it might be required if the main lane failed during the engine run. The way that the aircraft was tethered meant that symmetrical high power running was not any sort of issue.:ok:

We were very mean too. In the summer the hangar doors of TBK opposite would invariably be open during the day, the challenge was to see how long it took for us to make them close the doors to shut out the din. (Like I said, Concorde engineers were mean :}).

Good to be back
Best regards to all
Dude :O

What was the minimum maneuvering speed for Concorde
- At a typical takeoff weight?
- At MTOGW?

Also what was the typical climb speed
- At lift-off?
- Once 240 kts is achieved?
- At minimum maneuvering speed at typical takeoff weight?
- At MTOGW?

What was the minimum maneuvering speed for Concorde
It was expressed in the flight manual as "Lowest Authorised" speed, Vla, and didn't depend on weight. 0-15,000' Vla=V2 or Vref as appropriate, 15,000'-41,000' Vla=250kias, 41,000'-60,000' Vla=300kias

Also what was the typical climb speed I'm guessing you mean rate of climb rather than IAS?
- At lift-off? From memory Vr was around 200kts, V2 around 220kts and if restricted to 250kts (way below min drag) you'd get pretty poor rates of climb - about 1000fpm if you were lucky and IIRC - you'd quickly want to lower the nose, just barely climb and get her up to 400kts when she'd really fly...
- Once 240 kts is achieved? see above - but once you got her up to min drag (about 400kts at MTOW) things went better - about 4000fpm without reheat
- At minimum maneuvering speed at typical takeoff weight? At V2 she staggered up due the the drag of the slender delta wing at low IAS - but climb performance on three engines (in contingency reheat) at V2/MTOW was better than a conventional subsonic jet on three / MTOW / V2 due to conservative certification requirements of the TSS
- At MTOGW? Does the above answer your Q? Happy to add more if you need...

Edited to add, most transatlantic takeoffs were at MTOW - around 185 tonnes - and due to the slender delta aerodynamics, weight didn't affect performance as much as a conventional wing anyway because induced drag was the bigger player at slow speeds - and I've just completely exhausted my very limited grasp of aerodynamic engineering!!

Fuel penalty for speed limit?
 

That 250 kt limit had a truly startling effect on climb rate. Compared with an unrestricted climb, how much would that limit cost in fuel?

Well it took a long time, but Dudley eventually came up trumps!

http://i1080.photobucket.com/albums/...1/scan0110.jpg">

If anyone wants more, the source is an AGARD CP 260 by Cazenove and Ivroas ( but I have not been able to access the only URL that comes up on Google!)

CliveL

Thanks for that much better picture Bellerephon.

I have a bit more information now, although my French is very rusty so I may not have it all correct - CJ can probably correct me if necessary.

They did 8 flights over 10 hrs, preceded by about 30 simulator 'flights'. Most of the flight testing was looking at low speed behaviour, since that was where they expected to see most gains on Concorde, and where the most problems might be expected, but they did go up to 2.04M. The primary advantage was seen to be the possibility of using very aft CGs for takeoff to reduce trim drag - they flight tested as far back as 56% at around 0.4M (no consideration of limits from U/C location of course for this sort of testing). In addition they were predicting a weight saving of around half a tonne.

The simulator work sorted out the basic laws, where they tested a pure pitch rate feedback and a C* law with load factor and pitch rate terms. The pilots preferred the latter (which became in time the basis for the A320 laws).
The simulator was also used to establish the best ergonomics (movement and force harmonisation) of the sidestick.

The 'blue' electrical signalling system for elevons was replaced by the digital control and sidestick arrangement, keeping the 'green' signalling as a safety backup. Normal rudder control system was retained, as well as the mechanical backup.

In the general arrangement of the digital control system one can see clearly the genesis of the A320 design - two computers with the software written by separate teams etc.

Pilot reaction seems to have been very favourable, the aircraft being somewhat easier to fly than the basic Concorde (which was already pretty good ....).
In particular the paper suggests that the precision with which the aircraft could be positioned was much improved.
Stick force per 'g' was pretty much the same throughout the speed range at about 7daN/g, whereas on Concorde it varies from 20 to 40 daN/g - but on a sidestick rather than a control column of course.

One problem that did show up, although not peculiar to Concorde, was the sensitivity of these systems to structural response, particularly during ground roll.

Not contained in the report, but in a side letter from Dudley, is a remark that the guy most responsible for the development of the Concorde basic system and later in charge of the Airbus system thought that these Concorde experiments were the key to the success of the A320.

'Nuff said!

CliveL

Never get tired of this thread !


Very interesting about the sidestick, was the installation and testing purely for research / experimentation purposes or was it seriously contemplated for use in production Aircraft ?



If so, why was it decided against ?!

Basically an R&D exercise I think, funded by the French government in the same way as NASA might fund as similar research project.

It was done at just about the time that Concorde development was being abandoned, but had anyone seriously contemplated a Concorde 2 then ths would certainly have figured in the design.

A Side Sticky Subject
 

As I recall, they referred to this research project as a CCV (Controlled Configured Vehicle) design study. It would be great if we could get this confirmed, but they talked about subsonic drag reductions of 10 to 15% by flying (not taking off!!) with a far more aft CG than the norm. The 'system' I seem to remember, as a result naturally commanded some down elevon, which increased lift. As the aircraft could then fly with less alpha, I guess this is where the drag reduction comes from. (Clive, I wonder if you could find out through one of your contacts if this was true?).
I'd still personally like to know how the sidestick was integrated into the flying control system, I've been thinking and can not now believe that sidestick inputs could be simply input to the flying control system 'at resolver level'. Remember that the concept of the FBW system on Concorde was that resolvers were utilised as simple 4 wire synchros, and the pitch and roll axis utilised a CX/CDX/CT chain, which produced the error signal to the ESA's in the Autostab computers. Using a sidestick completely breaks up the chain, and my guess is that a seperate digital unit contained the flight rules which were summed against PFCU CT position and sidestick input would have been necessary. It is possible then that an analog output from this 'box' could be fed to the Autostab Computer ESAs and hence drive the elevons. I'm probably completely wrong, but I'd surely still love to know the truth. As you say Clive, ideal stuff for Concorde 2.

Best regards
Dude :O

Don't need no contacts Dude. The drag reduction came simply from flying at a lower AoA when trimmed at an aft CG. Less 'up' elevon, which is similar but not the same as 'down elevon' in an absolute sense, so less adverse elevon lift and work the wing to a lower AoA in consequence. Just an extension of the basic Concorde certification with a 'point' TO CG really.

They were certainly looking to study control laws that allowed flight at very aft CGs to increase aircraft performance, so yes, this was a CCV exercise, but they were also seeking experience with digital control and system architectures that could be transferred to other active control applications.

The 'sidestick' arrangement was virtually a complete A320 style arrangement using two computers and digital signalling throughout. For just 10 hrs they wouldn't need anything more complicated than a 'panic switch' to return control to the standard Concorde green system that was still there and available.

Clive

Thanks for the info Clive, now all is explained. (And I take your point about the elevon deflection).

Best Regards
Dude :O

Shirley the aft CG research for lower cruise drag could equally be done with conventional Concorde controls? Why is it associated only with sidestick control?

They weren't looking for cruise drag reductions; just takeoff climb improvements which would have required genuine relaxed stability - CGs back at the aerodynamic centre etc.
This entailed introducing artificial stability terms that would have been difficult in a purely analogue system such as the basic Concorde controls, so they decided to go digital.
Sidestick or conventional control column doesn't come into that of course - see Boeing vs AI FBW systems; but no doubt the French government saw the opportunity to get two for the price of one .....

CliveL

Did the Sidestick controller have the same authority as the Conventional Control yoke or were there 'hard limits' a la Airbus 320 and on ?

Same authority as basic controls - no envelope 'protections' or other hard limits so far as I know.

NW1

I assume in the US then you were restricted to 250 kts below 10,000 feet just like all other aircraft?

Why higher speed? That have to do with shockwaves and the resulting pressure distribution differences?

No, I meant the airspeed you'd be flying at while climbing (post takeoff)

Wow, that's pretty bad. You'd figure with a T/W ratio of around 0.40 you'd do far better than most other aircraft.

Were you allowed to get over 250 below 10,000 feet in the US, or UK? Regardless, what rate of climb would you get at that speed?

408,000 pounds?

With respect, that sounds more like the sort of climb rate associated with noise abatement rather than full power. Brian Calvert quotes 250 kts/2000ft/1000fpm/12deg attitude/reduced thrust for this. At 8000ft/400 kts/dry climb thrust he quotes 3000fpm, which is more the sort of number I would have expected (it is all a long time ago ......)

CliveL

Then what does 250 kts, 19-degrees of climb, afterburners engaged produce?

Noise, high rates of fuel consumption, mostly.

GF

<<I'm guessing you mean rate of climb rather than IAS? >>
<<No, I meant the airspeed you'd be flying at while climbing (post takeoff)>>

OK, then the answer to your Q's:
Also what was the typical climb speed
- At lift-off? About 200kts
- Once 240 kts is achieved? 240kts
- At minimum maneuvering speed at typical takeoff weight? Vla after takeoff was V2 until 15,000'. I.E. about 220kts
- At MTOGW? V2 didn't vary much by weight

Out of JFK we flew at Vmo once further than 12nms from the coast. Vmo=400kts IAS at low level.

Out of LHR overland the IAS restriction was 300kts until past the speed limit point early in the SID - much less draggy than 250kts and hence better climb rates. But you'd quickly be released to get to 400kts (barder's pole) where it was designed to be flown.

<<Why higher speed? That have to do with shockwaves and the resulting pressure distribution differences?>>
The flight envelope was bigger and more complex than subsonic types: it was developed in flight test and probably had many considerations involved. I think someone posted it earlier in this thread in graphical form (from the flight manual) if you want to see it. In practice, you had to be aware of three basic parameters - IAS, Mach and CG position (the CG "corridor"). Once understood, it wasn't that difficult to keep up with it...and the IAS and Machmeters had barber's poles handily programmed to show the limiting values (including, cleverly, max temp on the nose Tmo=127 degrees celcius).

Regarding climb rates - best ROC was at 400kts (MTOW) or 380kts (MLW). As speed reduced below that, drag increased and ROC reduced. At MTOW and 400kts you'd get about 4000fpm max dry power. At 250kts it was all noise and very few feet per minute - after noise abate procedures you had to lower the nose, just barely climb, and get IAS up toward min drag as soon as possible. With an engine failed go for 300kts minimum - Vmo as soon as you can.

<<shockwaves and the resulting pressure distribution differences>>
You had to avoid the "transonic" region due to these effects: maximum subsonic cruise was 0.95M due to the auto-stabilised flying controls become over-active as shockwaves started to "dance" around the airframe (usually asymmetrically). This calmed down by about 1.3M in the acceleration (when the intake ramps started to do their thing). To accelerate to 2.0M you needed reheat until 1.7M so you didn't hang around between 0.95M and 1.7M. FL260 was best for subsonic cruise because at that level 400kts IAS = 0.95M...

Per Person Operating Costs
 

At the time Concorde stopped flying was she making a profit?

My question however is this:
If we assume that the Concorde operation is not for profit, what should have been the cost of a ticket per person in 2003 to have broken even.

If she was still in service today, given airframe and engine servicing, fuel prices etc... what would have been the cost today of a ticket?

Heads up for Concorde enthusiasts -

http://www.pprune.org/aviation-histo...rde-pilot.html


Biography just published.