There's little need for commercial travelers to get anywhere on Earth any faster than they already can.
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights. I used to live under the flight path and the booms never bothered me, in fact I barely heard them.Shame really.
Quote from: nacnud on 11/12/2009 07:24 pmConcorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights. I used to live under the flight path and the booms never bothered me, in fact I barely heard them.Shame really.BA found it profitable on a few limited routes that fit both the range limitations of the jet, the over water limits, and had the necessary market size of luxury passengers willing to shell out thousands per ticket.The plane did not meet original range specifications, and that is what greatly limited its marketability. There was a proposal for an upgraded version that would have had slightly larger wings and greater fuel capacity to make longer range flights. Would have increased the number of possible routes ten fold.These are the little economic factors that may get overlooked in development but are make or break for the viability of the vehicle, same as happened with Shuttle, where the silica TPS' high maintenance requirements cut the possible sortie rate by 3/4 and thereby doomed the commercialization of the vehicle.
Quote from: mlorrey on 11/13/2009 12:25 amQuote from: nacnud on 11/12/2009 07:24 pmConcorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights. I used to live under the flight path and the booms never bothered me, in fact I barely heard them.Shame really.BA found it profitable on a few limited routes that fit both the range limitations of the jet, the over water limits, and had the necessary market size of luxury passengers willing to shell out thousands per ticket.The plane did not meet original range specifications, and that is what greatly limited its marketability. There was a proposal for an upgraded version that would have had slightly larger wings and greater fuel capacity to make longer range flights. Would have increased the number of possible routes ten fold.These are the little economic factors that may get overlooked in development but are make or break for the viability of the vehicle, same as happened with Shuttle, where the silica TPS' high maintenance requirements cut the possible sortie rate by 3/4 and thereby doomed the commercialization of the vehicle.It assumed hydrogen fuel, which is expensive and troublesome to handle.Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you breach the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
Quote from: 8900 on 11/13/2009 10:39 amQuote from: mlorrey on 11/13/2009 12:25 amQuote from: nacnud on 11/12/2009 07:24 pm......It assumed hydrogen fuel, which is expensive and troublesome to handle.Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you breach the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)in-place solid rocket, similar to how the military gets ramjets going.
Quote from: mlorrey on 11/13/2009 12:25 amQuote from: nacnud on 11/12/2009 07:24 pm......It assumed hydrogen fuel, which is expensive and troublesome to handle.Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you breach the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
Quote from: nacnud on 11/12/2009 07:24 pm......
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It assumed hydrogen fuel, which is expensive and troublesome to handle.Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you bridge the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
Quote from: 8900 on 11/13/2009 10:39 amIt assumed hydrogen fuel, which is expensive and troublesome to handle.Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you bridge the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)If you have a pile of money to throw at the problem, you develop what is called a combined cycle engine. There are two types:Rocket Based Combined Cycle (RBCC) uses a rocket engine in the core with the ram/scram jet built around it. This would use the rocket engine to reach high subsonic, transition from there to ramjet til mach 5, transition there to scramjet til mach 10-12, then back to pure rocket the rest of the way to orbit. NASA was developing this type of engine in the early oughties and was proposing a $400 million program to build a prototype test vehicle called GTX, which would have flown between 2004-2009 on suborbital test flights to Mach 15. This program was cancelled by Bush-Cheney in favor of Love And Missiles, but the engine is built in prototype form and tested in wind tunnels as well as having undergone Navier Stokes simulation.Turbine Based Combined Cycle (TBCC) uses a turbine engine core with the ram/scramjet built around it and is speed limited to the top end speed of the scramjet. This obviously is only useful on a first stage. One of the big engine companies developed this concept in its Pyrojet project and is capable of propelling vehicles up to mach 8. They have not as yet received any nonclassified customers for this engine...If you want to save money on developing expensive hardware like this, you can follow a proposal like my own in the link at the bottom of this message: tow launch, use ramjets up to mach 8, drop the ramjets, go the rest of the way on rocket power.You could alternatively launch from an airfield under rocket power and air refuel like Clapp's Black Horse proposal suggests.
Mlorrey may i correct you? First. since when ramjets works up to mach 10, they will melt down at around mach 6 (thats why the supersonic ramjets were invented).
Second the GTX program was an Air-augmented rocket and not a rbcc (as i know it) engine
if you want to see a real rbcc engine check out the x-43 program and a specially the x-43b with its ISTAR engine http://gltrs.grc.nasa.gov/reports/2005/TM-2005-213432.pdf plus there is no any rocket mode after the scramjet engine ignited ( thats why nasp failed) and the rocket mode that comes before the scramjet are just a little rocket injectors that turn on the ramjet mode .
As for the tbcc engine you are right but the tbcc engine is much more efficient than the rbcc engine and more durable ( but more complex) . for more info see here http://gltrs.grc.nasa.gov/reports/2001/TM-2001-210564.pdf and of course here http://www.wslfweb.org/docs/usg/afsabhyper.PDF
plus you may look at Darpa and Afrl latest work on the first stage for tbcc engine PROJECT VULCAN that aims to combine a turbine engine with a cvc or pde and than combine it with ramjet/scramjet engine to create a tbcc engine http://www.darpa.mil/tto/solicit/BAA08-53/VULCAN_Industry_Day_Presentations.pdf.
and if you have a time check out those studies http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212612.pdf , http://www.nianet.org/workshops/pdfs/NASA-NIA_ETO_Workshop_RJ_Litchford.pdf it seems that MHD Augmented Propulsion could give us a real SSTO. correct me if i am wrong .
The internal working of the combined engine will melt. I am not even sure you could make a variable inlet that will not melt at the very, very high heat. Also scram jets are VERY fuel inefficient. I saw a chart on them vs. turbo and ram jets. They are not that much better than a rocket that has to carry its own oxidizer. Fuel cost was a big problem with Concord. I think it paid its way on operating cost, but never paid back development cost (I am not sure on this). Maintenance cost was out of sight also. I think a military based cruise missile is all scram jets are going to be good for. Maybe not even good for that, but even then it is worth the money spend so far on just developing the concept.And I believe a ram jet needs a strong shock wave at the inlet to run. This makes them something like Mach 3 to run. I might be wrong on this, maybe someone can find us a link. Danny Deger
I'm pretty sure you're wrong. The engines weren't the limiting factor on the SR-71. Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.