Posts by user "pattern_is_full" [Posts: 14 Total up-votes: 0 Page: 1 of 1]¶

I just have a problem with studies that try to analyze human activities with reductionist statistics and math. Most of human achievement comes not from the masses (which perhaps can be studied that way) but from the outliers, the screwballs, the few who, through enhanced human cussedness and stubbornness, decide NOT to stay with the obvious, efficient or safe thing.

Concorde was a political animal, heavily subsidized because someone want it to happen, regardless of efficiency.

But then, ALL advances in transportation have been - and often still are - political animals, subsidized because someone with money and power wants it to happen, regardless of efficiency.

Columbus and Magellan were subsidized, to head straight out to sea when everyone else was sticking close to the coastlines. Look up the land grants to U.S. trans-continental railroads. Or the Air Mail contracts that supported the fledgling American air transport industry (and if you think "that was then, and this is now," - consider the budget of the FAA and NTSB and TSA, and the military contracts to Boeing and its suppliers.)

Cars? Consider how much tax money goes to build and maintain highway systems.

And consider the man who stood up in the U.S. Capitol and declared, "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth."

Concorde failed because it lost political support** - just like Apollo and the Space Shuttle. But most of the other aircraft on those charts would also be, or have been, far rarer in the skies (or never appeared) if they lost (or never had) their own political backing and subsidies, direct and indirect.

**If the French government had felt it was in France's interest for Concorde to continue, I'm sure money for, and political pressure on, Airbus would have been found to keep her flying.

And Concorde also faced substantial political opposition - its market viability would have been much higher if U.S. authorities had been as lenient with its "furrin" sonic booms as they had been with our own home-grown booms ("The Sound of Freedom!", it was called.)

Now - Concorde's technology was pushing 40, and no doubt that particular airframe would have faded away, just like the 727 and the other designs from the 1960's. To be replaced with something newer. But the future of supersonic transport in general was cut short not because of some statistical failing, but simply because it no longer shared the same political support as subsonic aviation.

@mozella

I guess my point would be that the same problems of supersonic flight existed in 1963-1976 as did in 2003. It was a technological challenge, and it was expensive.

The physics of the sound barrier did not change over that time. Nor did the constituent gases in Concorde's exhaust plume*, nor did the volume of the sonic booms.

However, in 1976, going supersonic was considered worth the costs, and in 2003 it was not, and that was a political (or if you prefer, cultural) calculation.

*Actually, I think the engines were tweaked to be less "smoky", but that may have been before commercial ops began.

Here's a link to the six development aircraft, with pix of all of them.

CONCORDE SST : PROTOTYPE FLEET

Several had different paint schemes throughout their history, so that may not be definitive. But there are variations that can narrow down which might be in your painting: long or short tailcone, and small window or large greenhouse cockpit visor.

Three of the six are British G registrations, and three have French F-numbers. Three have "...01" production numbers. As ChristiaanJ says, none would be registered "1-GEE" - but that might have been something added for a specific test flight or for some other reason unrelated to registration. They were repainted occasionally (including one painted in BA livery on one side and AF livery on the other, for a time.)

@ BN2A

I'm sure the real experts will "adjust" my understanding - but I believe Concorde, loaded for the transatlantic "Sierra" routes, could hit about 5000 fpm peak VS when climbing at 400 KIAS between ~10,000 and ~28,000 feet (wherever 400 KIAS = M 0.99). Leaving a coastal airport (New York, Barbados, Dakar), she would quickly be clear of land and could more or less transition directly through Mach 1 as soon as she reached 28-30,000 feet.

Those 4 Olympus engines could maintain Mach 2 with no afterburner at 50,000+ feet, so they had tons of excess power down low. Again my understanding is that they stayed at 100% dry thrust from brake release until TOD (except for subsonic cruise segments), with the AB added for takeoff, and when accelerating from Mach 0.96 through Mach 1.7.

Mach 2.00 was reached in about 30 minutes @ ~51,300 feet, depending on atmospherics - a relatively long slow slog compared to the initial climb and acceleration.

From inland airports such PDG or Heathrow, there was a "pause" for level subsonic cruise (M 0.94-0.96) in the high 20s until clear of the coastline by 20 miles (over La Manche or the mouth of the Bristol Channel.)

@ leb001 - greenhouse visor, BA livery, and short tail - probably G-AXDN (aircraft 101). Although I'll defer to the experts, as always.

@tomahawk_PA38

Here's a chart of AF Concorde routings: Concorde route

Given that BA and AF used the same "Sierra November/Sierra Oscar" EB oceanic routes, and Paris and London are about the same longitude, the decel point was likely nearly identical as well.

Handwritten note is a bit small, but I believe it amounts to "50nm east of BISKI."

Waypoints change, however, and BISKI no longer exists - the closest approximation to the actual decel point that I see on a current chart looks like it would be MOSIS. Mouth of the English Channel, just west of the Scilly-Ushant line.

Deceleration clear of land then takes you directly up the center of the channel to SSW of Southhampton (roughly, ORTAC), and then hang a subsonic left to Heathrow.

But I'd also love to hear if someone has more authoritative info.

Thanks, guys - I knew the OB route was out the Bristol Channel (described in detail earlier in this thread), and where the SN/SO eastbound routes rejoined at BISKI.

I see where "hanging the left" further out and decelerating up the Irish Sea and Bristol Channel is almost certainly correct, and makes more sense, for BA.

Thank you , sir!

I wish I hadn't "assumed" so much based on the AF chart.

According to this, 5500-6000 feet/1700 meters

Heritage Concorde

IIRC from one of the previous posts here, the strong differential required also defined the normal descent/deceleration timing and distance.

Power could only be reduced to 94% (N1 or N2, I forget which) or there would not be enough "bleed" air available to maintain the cabin altitude at TOD.
(although I could have misinterpreted that - it may have had more to do with maintaining the oblique inlet shocks, or hydraulics, or some such.)

Yep - Braniff crews trained to fly the full envelope. But for BA insurance reasons, there had to be a BA captain and flight engineer riding along in the jumpseats.

Another cute trick - the European airlines "sold" the airframes temporarily to Braniff, with new US N-numbers, so they could fly a "domestic" route without violating cabotage laws. Then "sold back" to BA or AF for the transatlantic legs.

CONCORDE SST : Braniff Concorde Services

I'll always bow out to the pros did the actual design and flying - but this book quote may be one insight.

The Concorde , Christopher Orlebar, 2017, p. 55

From the point of view of the most critical phase of human piloting, the radio altimeter was far more important in the scan than the baro altimeter. Baro altitude was generally a problem for the automated part of the envelope, or the FE, while the guys up front needed only spare it a glance (most of the time) only twice a minute or so (or less often?)

It's actually a window, with a red warning annunciator/flag behind it, that flags a problem with the functioning of the Vmo needle (yellow and black "speed-limit" barber pole.)

See section 4 on this web page: Heritage Concorde

On the extreme right - microscopic explanatory type (sorry!)

Since one of its triggering events is a loss of electrical power, the red flag will be showing unless the aircraft electrical system is powered up (my guess). So it shows red in most cockpit photos.

It takes a confluence of technologies and market structure to make something viable.

Concorde could not fly as anything but a very expensive subsonic aircraft over populated land, due to sonic-boom noise pollution - ruling out a lot of the marketplace. London-Africa/South Asia, for example, or Paris-Beijing. Or even NY-LA.

Flying the Pacific non-stop requires a doubling or even tripling of range to avoid refuel stops (sitting on the ground once or twice part-way, for 90 minutes or so, plus acceleration/deceleration time, defeats a lot of the speed advantage). Technology has advanced a lot, but nowhere near doubling/tripling the efficiency/range of an Olympus-type turbojet (which, counting the thrust recovery from the brilliant nacelle designs, was already amazingly efficient).

That's why regular Concorde service (and thus aircraft sales) was, practically speaking, limited to trans-Atlantic routes only.

Work is being done on shockwave/boom attentuation, which might open up far more markets. But it is still small-scale experimental.

Airbus recently proposed - on paper - a boom-defeating flight profile: rocket-assisted vertical acceleration to supersonic (boom travels sideways rather than towards the ground) combined with Mach-4.5 cruise at 104-115,000 feet (30-35km altitude attenuates the boom effects at ground level) and near-vertical descent while passing back to subsonic. Quite a roller-coaster ride!

Using liquid H2 fuel that gets it range from London-LAX at Mach 4.5 - but carrying only a dozen or so pax (hydrogen tank fills the rest of the fuselage).

ATC Watcher

it was possible - if the total route was short enough. And you had ~60000 kilos of fuel to waste.

Key points:

- Concorde's speed was directly related to altitude - going subsonic required descending to FL400 or below. With a corresponding decrease in Mach/true airspeed. Very poor fuel efficiency below Mach 1.7 - couldn't hold speed without afterburner/reheat. Don't forget how much Concorde's flight profile and range absolutely depended on turning the engine/nacelle system into a ramjet from Mach 1.7-2.02 to work "commercially" at all. The old "at Mach 2.02 cruise, 85% of the thrust came from the nacelle" idea.

- to get back to supersonic flight required repeating the whole climb-and-accelerate profile with AB/reheat fuel flowing by the tonne, until re-acquiring Mach 1.7 at FL400\xb1.

which leads to:

Nope. It was far more efficient to simply maintain Mach 2.02 and bypass India (and Sri Lanka) to the south. Circling all the way around them while maintaining supersonic speed and altitude used less fuel than: descend - slow to subsonic - cross India on a direct route - climb and accelerate back to supersonic.

You can google up some maps of Concorde routes (e.g. Paris-Dakar, Dakar-Rio). Actual routes, not airline "schematics." And see that it was almost always preferable and more efficient to get out over an ocean ASAP and get the ramjet effect going at Mach 1.7+, and then stay out over water as long as possible. Even if it meant an indirect "dogleg(s)" route covering more miles. Except for some intentionally "transcontinental" routes like KHI-CCU, Perth-Sydney, Dulles-Dallas.

There are folks here who can correct me, but in the meantime, what I think I know is....

The DC-Dallas route, entirely over populated land, could not be flown at supersonic speeds (regulations, noise pollution, sonic booms), but Concorde could do it in high- sub sonic cruise at around Mach 0.95, somewhat faster than the norm for regular subsonic transports.

I believe the DC-MIA route was flown mostly supersonically, by climbing subsonically at Mach 0.95 straight down the Potomac to the Atlantic at Norfolk, Va., and then, 20+ miles offshore, turning SW towards Miami and making the supersonic acceleration-climb out over the water. Remained offshore (dodging the coastal bulge of the Outer Banks) until about 250nm from Miami. where the descent/deceleration phase would slow it to subsonic speed before getting too close to the shoreline.

Once at ~28,000 feet at Mach .95 - and over the water - it only took a few moments, after turning on the reheat/afterburners, to punch through Mach 1, and maybe 20 minutes (depending on weight) to reach 51000 feet* and Mach 2.02 (air termperature permitting.) And maybe 20 minutes for the deceleration/descent to Mach 0.95 at ~34000 feet.

(*I believe the afterburners were switched off at Mach 1.7 - usually about 42000 feet? - at which point the dry thrust of the engines and fancy shockwave-pressurized nacelle design could maintain the IAS and (reduced rate) climb (and increase the Mach) all by themselves.)

Across the Pond, short "experience flights" from both Paris and London were made from time to time - get out over the Atlantic, light up the afterburners, and tool around at supersonic speeds for some part of an hour before returning to base.

I'm pretty sure subsonic flight was never really efficient at any speed. Concorde was dependent on Mach 1.7 or so (and high altitudes) to maintain the efficiency of nacelle thrust modulated by supersonic intake shockwaves, without very thirsty afterburners. I think that over the Atlantic, losing just one engine (25% of thrust) was enough to make it instantly a fuel emergency situation - you were going to come down into thicker air and fuel burn would skyrocket.