Slashdot Mirror
Son of Concorde
targo writes "BBC reports that EADS is considering a new generation hypersonic commercial aircraft. "Son of Concorde" would be twice as fast, carry twice as many passengers while being much quieter than its predecessor. It would get from Tokyo to Paris in just two hours, US destinations are not mentioned.
However, as Japan's failure last summer suggests, it might not happen too easily."
2 hours to cover half the world... It almost sounds like a low-earth-orbit travel arc.
Supercruise is a fairly easy-to-understand phenomenon; in effect, it requires two things:
- lots of thrust from the powerplant;
- subsonic airflow in high quantities through the engine due to the way a "conventional" turbine operates, with slightly supersonic exhaust flows.
Normally, a turbine can't attain supercruise because of the latter; the airflow needs to be slowed considerably going through the powerplant in order to stop a shock stall (where the supersonic shockwave suffocates the powerplant).The powerplant behind the F-22 (Pratt&Whitney F119-PW-200) attains this primarily though a few good engineering tricks such as single-crystal-cast blades with a slightly shallower angle of attack than most; thus allowing the engine to operate at a higher temperature and pressure internally than is "normal". It has a lower bypass ratio (the ratio of cool air passing around the engine to that going through the engine) than most fighter-class engines; thus, it needs a smaller front fan, which in turn reduces the area causing a shock stall. It also wears out quicker, but that's another matter entirely. :)
High bypass ratios are great for fuel efficiency at subsonic speeds, but by virtue of the way these turbines work and their tendency to shock-stall when confronted with a supersonic airflow, are not much good for supersonic flight, and not for the nearly-supersonic airflows that supercruise requires.
A typical mid-to-high bypass turbine used in a fighter will have a bleed air system to reduce the airspeed running through the turbine; this has to be counteracted by dumping raw fuel into the bypass & exhaust (i.e. afterburner). Indeed, to get much over M1.0 the F22 needs to employ this same trick. A low bypass turbine can operate with input airspeeds closer to M1.0, which in turn means less air needs to be bled, while still producing a slightly supersonic exhaust out the rear end.
Unfortunately you have neglected what happend with the Concorde that impact your "math" quite significantly,
First of all, Concorde never flew to Tonkyo. The flights to Paya Lebar, Singapore had to stop over at Bahrain for refueling, even a quick turn around will cost you a couple of hours at best. The route flew over what was nearly all land so it had to fly at subsonic speeds on large portions of the journey (M.95), after a while even flights over the Saudi desert had to drop to subsonic speeds because of nomads whose camels reportedly stopped breeding because of the supersonic boom.
So that's why you had journey times in the 8-9h region, if they flew the journey at 2M nonstop then you would expect to half that time, so a plane going 4M nonstop could be in the region of 2h.
So much for you logic, nevermind the math.
Since we were referring to Concorde earlier, I used the calculator at British Airways for flights London (UK) to Sydney (Australia). That's a long flight, pretty much half way around the globe.
The cheapest economy fare is GBP 511-848 (return);, Business class is GBP 1,927-2,570; 1st class is GBP 2,891-3,220. That's a huge difference, yet people are willing to pay it, just for more leg room.
You don't think those same people would pay business class rates for cattle class seating---but get there in a few hours?
Protoplasm. Quiet Protoplasm. I like quiet protoplasm.
It appears the Beeb has confused peak speed with average speed.
According to the US Department of Agriculture, the Great Circle distance from Paris to Tokyo is 6033 miles. Let's round that to 6000 mi. The speed of sound varies with temperature, but using 750mph makes the math easy (at aircraft altitudes, the speed of sound is closer to 700mph).
If it could hold the fuel, the Concorde at Mach 2 (1500mph) could do 6000 miles in four hours. If the EADS jet achieves Mach 4 (3000mph), it could do 6000 miles in two hours. If the entire distance were covered at cruising speed.
My impression (purely from being a passenger) is that it takes half an hour or so for a typical commercial airliner on a 1000 mile flight to reach cruising speed and altitude; the plane will then be at cruising speed for about 60 minutes, and then another 30 minutes is spent in deceleration. Of the 2 hours spent in the air, only half of the time is actually spent at crusing speed.
How long would it take for the EADS-SS to reach Mach 4? And how long would it take it to slow down from that speed to the typical 150mph (+/-) landing speed that current runways are designed for? I doubt the typical passenger is prepared for Michael Schumacher / John Force g-forces on takeoff and landing.
Let's say the EADS-SS takes 45 minutes to reach Mach 4, and another 45 minutes to drop back to landing speeds. Assuming linear acceleration and deceleration, that's an hour and a half spent at an average speed of 1500mph. So 2250 miles of the trip takes 1.5 hours. Transiting the remaining 3750 miles at Mach 4 (3000mph) would take another 1.25 hours, for a total trip of 2.75 hours. [Ignoring any ground taxi times or other delays.]
I would think, fuel-wise (which is basically the only marginal cost of airplane flight), that going from Mach 2 to Mach 4 is more expensive than going from Mach 1 to Mach 2. On the other hand, Mach 1 -> 2 is done in denser air than Mach 2 -> 4, so maybe not.
This could be a great question for a final exam in Engineering Analysis and Synthesis.
It's not clear that the Sonic Cruiser was scrapped for the right reasons. It was probably board of directors politics rather than an informed technical and business decision that killed this bird.
In general, Boeing is hurting; it's a cyclical industry and even in the best of times they have to take huge financial risks with new models.
Also, they seem to have a really antagonistic relationship with their unions, and it so happens that the mechanics and even the engineers were on strike at the time that the Sonic Cruiser had been announced. Under these circumstances, a couple of board members including John F. McDonnell, relics from the old McDonnell-Douglas corporation, were able to veto the project as "too expensive".
There's been a lot of articles about Boeing's descent from a dynamic innovator to a stodgy defense contractor, partly caused by its merger with Mc.D. See this article for example.
It's sad to see a once great company fading away.
it's = "it is"; its = possessive. E.g., it's flapping its wings.
I think the parent means planes that have an unstable airframe, like the F-22 Raptor for example, that wont stay in the air without computers keeping it stable. Take that 777, make all the computers in it malfunction and it will still fly, glide at least. Do that to an F22 and it will drop like a rock... I'm not aware of any civilian airliners that would be like this, but maybe they are coming. I would feel less safe flying in one of those than a "traditional" airliner.
Indeed. Air routes aren't determined based on the shortest path between two points, they're based on "hops" from one airport region to another (regardless of whether they actually land at the airport). Easier to keep track of the aircraft, but terribly inefficient.
Concorde didn't use its afterburners while cruising.
http://www.concordesst.com/powerplant.html
Perhaps you should think before you post?
Single-crystal titanium blades are common in high performance engines, not just the F119-PW-100 (note it's 100, not 200).
"A typical mid-to-high bypass turbine used in a fighter will have a bleed air system to reduce the airspeed running through the turbine; this has to be counteracted by dumping raw fuel into the bypass & exhaust (i.e. afterburner). Indeed, to get much over M1.0 the F22 needs to employ this same trick."
The F-22 has demonstrated supercruise at 1.53 mach, i.e. it has reached speeds significantly above 1 mach without afterburner use. Top speed in level flight, at altitude, is probably no greater than 1.9 mach due to the deletion of variable intake ramps (which the YF-22 had).
Supercruise is generally used as a term to describe an aircraft capable of maintaining supersonic speeds without the use of afterburners. Supercruise is rarely used to describe the ability to accelerate to supersonic speeds without afterburners e.g. the ability to push through the transonic region.
Supercruise as defined in the context of the F-22 is the ability to cruise M1.5 @ 50,000ft without the usage of afterburners. F-22 is unique in that it can accelerate to its supercruise speed without afterburners. However current information suggests afterburners will be used operationally in the transonic region to achieve M1.5 due to payload weightings (no publicly disclosed test has achieved M1.5 without using afterburners to attain that speed when fully laden). The only tests to attain the aircrafts supercruise speed without afterburners have been un-laden tests.
There have been plenty of aircraft capable of supercruise after using afterburners in the transonic region. SR-71 could supercruise at M1.8+, Concorde was/is capable of supercruise at M1.4+. Both aircraft would routinely supercruise at those speeds during their operational life. It might surprise you to learn that the Rolls-Royce/SNECMA Olympus 593 Mark 610 (used in concorde, designed back in the 60's) could be used to accelerate the plane through the transonic phase without afterburners, but was found to be more expensive operationally than using the afterburner from M0.95 to M1.4.
A revision of the engine was under development in the late 70's before cancellation of the concorde mrk-II project which would have made transonic acceleration economic. The intake system on the Rolls-Royce/SNECMA Olympus 593 engine is even today still a state secret and had to be removed from the planes before they could be put on public display.
As a comparison the engine specs state that:
Rolls-Royce/SNECMA Olympus 593 Mark 610
31,350 lb st dry thrust
38,050 lb st with afterburner.
F119-PW-100
35,000 lb st dry thrust
39,000 lb st with afterburner.
"The real reason Concorde failed was that it carried too few passengers, used too much fuel and protectionism in the US blocked landing at the major airports until the consortium stopped manufacture."
Not only in the U.S., but also in Europe.
"Airbus will be building a 1200 seat aircraft, which with the current glut of 600 seaters is probably the sweet spot in the market at this point."
Whoa there! 1200 seats? The double-decker A380 currently undergoing early construction seats about 560, roughly 100 more than the 747-400 (the current largest capacity civil passenger aircraft). There are no 600 seat aircraft in service at this time, and certainly not any 1200 seaters for a while.
not quite. I work for an airline. A positively giddy amount of work goes into flight planning. Shortest path comes into it if you're trying to be quicker, but these days fuel burn and thus cost matters a lot. Trying to maximize your tailwind, reduce headwind, avoiding restricted airspace and following airways (like an interstate in the sky) for air traffic control reasons. This might answer the "hops" you talk about. Its navigational beacons which are often at airports.
Which brings us to tracking. If you're over the open ocean you follow tracks. Its a bit like hunt for red october going through the canyons. This speed, at this altitude through these points to maintain separation. Over land, you can be spotted within a couple hundred miles by your ground-air comms. And theres a lot of those. You are almost right on the airports, depending on where you're flying, type of aircraft and and how many engines you must be within a certain flying time of a suitable airport. Its called ETOPS.
So lots of things to worry about, including weather, but it typically starts with shortest distance.
While the XB-70 Valkyrie was not quite as fast as the SR-71, it was nearly as fast (Ben Rich in "Skunk Works" tries to tell us it was only Mach 2.5, but that was only for the number 1 XB-70 because when they took it up to Mach 3, parts melted off (the brazing on the honeycomb steel panels came apart) and got ingested in the engines). They fixed that problem on the number 2 XB-70, but they crumped the number 2 XB-70 in a fatal rear-end collision doing a photo op with a bunch of "chase planes", and the XB-70 parked inside the Dayton, Ohio Air Force museum is the Mach 2.5-capable number 1 plane.
Anyway, the XB-70 also experienced the unstart problem. The XB-70 was used for aero research for the SST, and the honkin' sonic booms from the XB-70 were part of what helped discourage the SST. It was also noted that unstarts were pretty scary and would need to be remedied for the SST.
Concord/Concorde has movable inlet ramps for the shock waves -- I wonder if it ever experienced unstarts?
Also, the XB-70 was supposed to use "compression lift" -- they stuffed the six engines in this big, wide pod under the delta wing to get lift from the shock wave. This was supposed to make it much more aerodynamically efficient than the typical supersonic aircraft, allowing it to have intercontinental supersonic cruise range. I also heard that the compression lift didn't quite work up to the expectations of the wind tunnel model tests.
Is anyone considering whether compression lift (apparently there is better fluid modeling software) can result in a more fuel-efficient/longer-range SST?