Posts about: "Glide" [Posts: 10 Pages: 1]

I feel like the fog is begining to clear and I am getting a slight understanding of how she flew. I was hung up with her flying at Mach speeds where as she was flown at an IAS (specific the the profile she was in). The Mach speed, especially when high, was a result of the temperature and not because she was f a s t ! The altitude flown was due to temperature and weight of the areoplane. This is true of all aeroplanes but due to the extreme environment this was more true of Concorde?

The subsonics have issues with Coffin Corner (I think I read that one Airbus model had somehting like 7kts between the high and low end of the envelope when up high); did Concorde have this "problem"?

I remember reading the BA Concorde flew with 2 Captain Pilots (and of course the most important Flight Engineer) and when I was watching The Rise and Fall of the Concorde , I was looking for the 4 bars in the RHS. Didn't see one but on the Air France Concorde the RHS pilot had 3 stripes. Was this correct or are my "little grey cells" confused?(sorry can't type a Belgium accent )

I don't know why this popped into my head but what was her glide ratio if all the engines stopped? Maybe because I remember from my early training being told the a B707 had a better glide ratio than the PA28-140 I was learning in. Now that was an eye opener at the time.

Just wanted to add my voice to those encouraging you to continue... this thread is great stuff! What a fascinating ship; makes my day job on the B744 look plain in comparison

I too would like to ask what her idle thrust glide ratio was? From Bellerophon's post: Sounds like a typical airliner 15:1 glide ratio? (but down from FL600 in 22 minutes ?)

Biggles78


...The altitude flown was due to temperature and weight of the areoplane. This is true of all aeroplanes...

Sadly, it isn’t, as subsonic aircraft are allocated a specific cruising flight level and often - for example on the North Atlantic Track system - a specific cruising Mach number as well, and no deviation from that clearance is permitted without specific permission from ATC. Obviously everyone flight plans at the most economic heights and speeds for their aircraft type, but in busy airspace not everyone gets what they want!

Think of your flight plan as being Angelina Jolie, and your ATC clearance as being your wife. Your flight plan is what you’d really like to have, but your ATC clearance is what you’re going to have to live with!


... altitude flown was due to temperature and weight of the areoplane...this was more true of Concorde?...

Subsonic aircraft could equally benefit from using cruise-climb techniques (early long range aircraft crews knew all about cruise-climb techniques and used them when able) but with the large number of subsonic aircraft now using the world’s airways it is impractical for ATC to allow them to drift up and down at will, and so they are assigned specific cruising altitudes.

Few other aircraft got up to Concorde’s cruising levels, and so ATC were able to issue much more flexible clearances to her.

A typical Concorde ATC clearance would have allowed her to accelerate to M2.00 whilst operating within a "block" of altitude, rather than at a specific flight level. Typically this block clearance would have been to operate anywhere between FL450 up to FL600 without restriction.

So, unlike subsonic aircraft assigned a fixed cruising altitude such as FL350, Concorde could, and did, drift up or down, and was thus able to remain at the optimum altitude for the prevailing conditions throughout most of the flight.


... I remember reading the BA Concorde flew with 2 Captain Pilots (and of course the most important Flight Engineer)...

Concorde operated, as did all 3 crew aircraft in BA, with a standard crew of a Captain, F/O and F/E.

A small number of trips had two Captains on board (or two F/Es for that matter) when training or checking was going on, or an extra crew member was carried for PR purposes, but otherwise, the vast majority of occasions, just the standard crew was on board. Everyone preferred it that way, especially the F/O and F/E!


... The subsonics have issues with Coffin Corner (I think I read that one Airbus model had somehting like 7kts between the high and low end of the envelope when up high); did Concorde have this "problem"?...

Have a look at this picture of G-BOAE, cruising at her maximum certificated altitude of FL600, en-route to Barbados on 16 August 2003:





The available IAS speed range is shown on the ASI, and lies between the yellow and black Barbers Pole, currently indicating 440kts, and the white bug set to 300kts, the VLA ( L owest A uthorised speed) at this altitude.

The available Mach speed range is shown on the Mach meter, and lies between the yellow and black Barbers Pole, currently indicating M2.05, and the yellow bug which indicates the lowest Mach number allowed for the current aircraft CG position (the AFT limit) currently showing M1.35.

So, given that at her maximum altitude she had a speed range of 140kts IAS and a Mach range of M0.7, we can see that coffin corner was not a problem!


main_dog


...I too would like to ask what her idle thrust glide ratio was...

By my calculations, the figures quoted for a straight in approach, give an average glide ratio of around 20:1, however these were for a standard decel/descent, and on Concorde the early part of the decel/descent was not flown at idle power.

A considerable amount of power was left on initially, around 94% N2, for various reasons, and only below M1.0 were the throttles usually selected to idle.

I hadn’t noticed it until now but there does not appear to have been a chart giving glide distance at idle thrust!

However, since the speeds to be flown during the “4 Eng Flame Out” procedure were not too far from the normal decel/descent speeds, I’ll hazard a guess (and that is all it is) that the glide distance from FL600, with no thrust, would have been about 150nm, giving a glide ratio of around 15:1.

Sorry Bellerophon, a badly worded question from me but you gave a really good analogy. Gonna remember that even though I don't like my Flight Plans have collagen filled lips. I will see if I can reword it to make it comprehensible.

Thank you for the Instrument Panel image that I have now added to my collection. What is the Yellow Arc on the Mach metre that starts at about M1.12?
Do you remember if you had a signifigant headwind at that stage? I notice that the G/S is 1,139kts was this fairly standard for an East-West flight? (DUH me. Just read the fastest crossing was an east-west direction. Winds must have been quite favorable) I am now guessing the displayed G/S would be fairly typical, plus or minus a bit.
The Glide Ratio, even if it is a highly educated guess, is impressive. I would not have expected it to have been about the same as a B747. How many more times is this Lady going to surprise me with her performance.

Also notice the ball is slightly off to the left even though it is still inside the lines. Was this normal or does it need a tad more rudder trim? Can't imagine it is really out of balance.

Was that because of the tight fit on the flight deck or because we really don't like others in our workspace?

ChristiaanJ thanks for the CoG diagram. That I am still getting my head around. There is a large range at the bottom and top of the speed range but fairly narrow in the mid speed range. Seems like 165T was a less complex balancing act than it was at 105T.

The center rear fuselage gear unit, what was that for? I have seen it deployed on many occasions but I can't for the life of me remember if it was during T/O or LDG however it didn't seem to be extended every time the aeroplane flew. Was this used during loading so she didn't accidently "rotate" at the ramp or to avoid a tailstrike during LDG? I can't imagine an over rotate during T/O.

And a big Thank You to Bellerophon for sharing his knowledge with this thread.

On the ITVV Concorde DVD the Captain explains that during the cruise climb at mach 2 the auto throttles were armed and would be used as required. Then during descent the throttles were gradually pulled back whilst the autopilot was given an IAS of I think 350 knots. Therefore the plane would have to descend to maintain that speed. He explained that the power settings were chosen to ensure that there was sufficent cooling etc.
My query is if an autoland was to be undertaken was the auto throttle system able to maintain the required landing speed or would the pilot have to manage the throttles? I guess that decreasing or increasing the pitch to control speed when on the glide slope would not be a good idea.
Thanks again
Nick

Diesel8 made this observation which, given he/she was in New York, was hardly surprising that people stopped to look. I live in south London under an area where aircraft are not far from acquiring the glide slope for 27L or departing from 10R, so aeroplanes are a part of everyday life. Having said that, they're not at the moment because of the runway work! But I digress.

I have loved aeroplanes since I was very young - I genuinely understood Bernouli's principle when I was about nine - and I always looked at aeroplanes, indeed I still do. But most of the time, when the engine note was obviously a 747 or 727 (noisey!) or some such, I would perhaps concentrate on what I was supposed to be doing. But in the early evening, the absolutely inimitable sound of 593s would draw the eyes of nearly everyone in our area. We saw her every day and yet we all looked. Always. Extraordinary.

Not being in the flying profession, I only have two Concorde stories of my own. Back before the M25 was completed and it stopped at Poyle, I would take the opportunity to use what became the Poyle northbound on ramp as a 'plane spotters' place. One evening I stopped in the gathering dusk and got out to watch a few planes. 737s and 757s abounded as the light faded, leaving a broad, light blue band across the horizon, tinged with peach and little colour anywhere else.

Then I heard her on her way and the old heart beat a bit quicker. Suddenly she was up and passing and my mind's eye took the photograph I always wanted and now will never get. Concorde, silhouetted against the horizon, the cabin lights just visible, but the four, electric blue reheat exhausts - including shock diamonds - the only other colour in the monochrome image. Unforgettable.

The second was day time. I was parking my car in the north car park - when it was basically all the way down one side of 27R. On my way, I think, to Stockholm Arlander, I was ignoring the succession of 'light iron' going by very close. Again, I heard her light up and just stood and waited. Fabulous sight of Concorde, just rotating as she passed me and climbing away to the west trailing thunder ..... and every car in the north car park sounding their tribute when the reheat set off their alarms.

You just had to look - every time.

Roger.

Mr Vortex

An ejection was recommended because it was possible, not that was necessarily impossible to land a Draken dead stick. F-16s have done a number of them, I witnessed one at KTPA. There was a video of the HUD view of one at NAS Glenview, IL.

To your question, it would depend on distance to go to the airport, glide ratio (high but probably not terribly worse than any conventional airliner) and most importantly the capability of the RAT providing hydraulic power.

M2dude , any idea of the min IAS for the RAT to provide the juice and hydraulics? Would it be as low as Vapp minus some margin?

GF

The "venom" is in the tail of your question.....
Best glide angle for Concorde is in the order of 1:10, so with an multiple failure at 40,000ft (7.5 miles) your "nearest airport" would have to be well within a distance of 75 miles.
(BTW, I think somebody earlier already mentioned that a large part of the actual descent from top-of-descent was with the engines barely above idle, so that it was much like a glide. It was during the final hold, approach and landing, that it was preferable to have a few engines left.....)

Four-engine surges have happened a few times during flight testing, but I don't think there ever has been a four-engine flameout.

Re the SAAB Draken, I would think a dead-stick landing would be possible, but only IF you could arrive 'overhead' at about 10,000ft and IF you were well aware of the horrendous sink rate 'on the back of the drag curve' once you committed to the final approach and landing.
Even the F-104G, not known for its gliding qualities, could be and has been landed dead-stick - there is a section on the subject in the flight manual. On the 104, things were further complicated by the fact that without an engine you also lost the "blown flaps", so your landing speed was a lot higher.

In Western Europe, with its densely populated areas on the one hand, and a lot of airbases on the other hand, there were certainly cases where you thought twice before 'punching out'.

CJ

quote:I don't know why this popped into my head but what was her glide ratio if all the engines stopped? Maybe because I remember from my early training being told the a B707 had a better glide ratio than the PA28-140 I was learning in. Now that was an eye opener at the time.unquote

A lot depends on how fast you were flying. You can get pretty good values of Lift/Drag ratio (that defines the potential glide slope with all engines operating, if that is not a contradiction in terms) from the Concorde B pages of the Concorde SST site. The actual glide slope with engines out would have been a lot worse than those numbers because of windmilling and (supersonically) intake spillage drag.

Nowhere near any subsonic values!

Clive

Wow, what a great thread! I started reading it yesterday and am up to page 19 so far! I flew on the wonderful white bird once, in 1999, a Manchester - round the bay at Mach 2 - Paris flight in G-BOAD. And the wonderful thing was I did the entire flight, push back at Manchester to parking at Paris, in the jump seat! What a fabulous experience - thank you Roger!

Here's a picture I took as the aircraft turne left towards the French coast:



One memory is climbing through 50,000 feet over South Wales before turning down the Bristol Channel. It was glorious August day and I had a great view forward past the captain and particularly out of the left window. The speed over the ground at Mach 0.95 seemed noticably faster than a subsonic jet, and that view was breathtaking! The Bristol Channel was edged in golden yellow beaches, and I could see right across south west England to the English Channel. In my headset the controller called another aircraft; "Speedbird 123 if you look up now you will see you are about to be overflown by Concorde". I leaned towards my side window and there was Speedbird 123, a tiny scurrying beetle miles below us. From this height the fair-weather cu looked as if they were on the ground - like small white splodges from some celestial artist's paint brush.

We cruised at Mach 2 and 60,000' over the Bay for a while and the pax came forward to view the flightdeck. I was amazed how patient was the supernumery captain who was answering the same questions over and over again was (the flight crew were too busy to chat).

The approach to CDG looked far steeper than other airliner approaches I had witnessed from the flight deck; more like one of my glide approaches in the Chipmunk! But it wasn't, of course, as we were following the 3 degree glideslope. I guess it was an illusion brought about by the steep pitch angle.

I remember the captain resting his hands on the throttles as they shuttled back and forth under autothrottle control, the smooth touchdown, the 'landing' of the nosewheel followed by full forward stick, and thinking "we'll never make that turn off". Then on came the powerful reverse and the brakes, I was thrust foreward in my harness, the speed disappeared, and we made the turnoff easily!

Oh, and that stange bouncy ride in the flight deck on the ground as the long nose forward of the nosewheel flexed over every joint in the taxyway. So bad at times it was difficult to take a photograph!

What an experience!

I have a question which I hope hasn't been answered in the pages (20 to this one) that I've yet to read.

From an earlier post I understand that the anti-skid used a rotational reference from the unbraked nosewheels to compare to the rotation of the mains, and that with gear down in the air a substiute nose-wheel referance is supplied which, because the mains are not yet rotating, allows the anti-skid to keep the brakes off.

But what happens when the mains touch down with the nosewheels still high in the air? What (if anything) inhibits wheel braking until the nosewhels are on the ground (and therefore rotating)?

Also, this thread started with a question about the lack of an APU. When Concorde was parked could the aircon and cabin lighting be powered by external electrical power, or did the cabin aircon without engine power require an external 'aircon unit' to be connected? Or was aircon simply not available without at least one engine running?

And one for Landlady or any other CC. If a table top was set up between the cabins during service, how did the 'front' crew service the first 2 rows of the rear cabin?

Being 'up front' for my entire flight, I missed out on the cabin service. But superb though I'm sure that was, under the circumstances it's not something I regret!