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BBC Hypersonic Jet ready to be launched
The Scramjet Engine known as Hyshot III will be the first of a series of International Scramjet launches in Australia. If all goes well it will be launched Saturday.
Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.
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BBC Hypersonic Jet ready to be launched
The Scramjet Engine known as Hyshot III will be the first of a series of International Scramjet launches in Australia. If all goes well it will be launched Saturday.
Looks like there is international competition in the area of hypersonic research. Perhaps this will be the real start of the next space race.
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Nah, not really. Scramjet technology, for all its coolness, doesn't really make much difference until we're talking higher mach numbers. Reasonably speaking, you need to be able to ignite around Mach-3 or 4 and burn up to Mach-20 to build a true single-stage-to-orbit vehicle. Two-stage-to-orbit vehicles really don't need to bother with Scramjets, enlarged SR-71 Blackbird engines, updated with modern materials, is enough for that.
These engines are all small and cylinder shaped too, which doesn't have much application to spaceflight except as maybe strap-on boosters for conventional throw-away rockets... Oh, and hypersonic cruise missiles of course, kind of a poor-mans ICBM. It takes far, far more engineering to make a Scramjet airplane, since the engine and the airframe can't be seperate like conventional aircraft, but have to be designed to work together... and it still has to fly.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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Nah, not really. Scramjet technology, for all its coolness, doesn't really make much difference until we're talking higher mach numbers. Reasonably speaking, you need to be able to ignite around Mach-3 or 4 and burn up to Mach-20 to build a true single-stage-to-orbit vehicle. Two-stage-to-orbit vehicles really don't need to bother with Scramjets, enlarged SR-71 Blackbird engines, updated with modern materials, is enough for that.
These engines are all small and cylinder shaped too, which doesn't have much application to spaceflight except as maybe strap-on boosters for conventional throw-away rockets... Oh, and hypersonic cruise missiles of course, kind of a poor-mans ICBM.
So maybe an SR-71 Blackbird engine can be supped up for two stage orbit but the faster the first stage can go the smaller the second stage vehicle needs to be to deliver the same payload. Or equivalently the smaller the first stage needs to be. This must have some economic advantage.
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Not the SR-71 moldlines and engines themselves, but something not too unlike them. The big Mach-3 Valkyrie bomber (that Aviation Week thinks actually was used to carry a military suborbital spaceplane) would be a decent starting point. Make the engines, called coaxial turbo-ramjets, withstand even higher temperatures but for shorter "sprints" to launch speed/altitude. This could be accomplished, and the maximum altitude increased, by injecting liquid oxygen and/or water into the turbine, which has been shown to extend the performance of conventional fighter jet engines up to Mach-4 or Mach-5.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Not the SR-71 moldlines and engines themselves, but something not too unlike them. The big Mach-3 Valkyrie bomber (that Aviation Week thinks actually was used to carry a military suborbital spaceplane) would be a decent starting point. Make the engines, called coaxial turbo-ramjets, withstand even higher temperatures but for shorter "sprints" to launch speed/altitude. This could be accomplished, and the maximum altitude increased, by injecting liquid oxygen and/or water into the turbine, which has been shown to extend the performance of conventional fighter jet engines up to Mach-4 or Mach-5.
You still need a pretty good mass fraction to get to orbit from Mach 3 or 4 don’t you? At least I think this was one of the points of Jeffry bells article debunking the secret military space plan as technically unfeasible.
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BBC Hypersonic Jet ready to be launched
The Scramjet Engine known as Hyshot III will be the first of a series of International Scramjet launches in Australia. If all goes well it will be launched Saturday.
It is interesting that other nations are launching such flights from this local..
I am curious if GCNRevenger use of them as a booster is possibly a good use to make them of a flyback type or to place them say at the end of an ET at the outer locations. Possibly keeping the inrush vent closed and feeding them with oxygen and Hydrogen until it reaches hyper speed then switching over to scramjet mode.
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Mach-4 at 80kft probobly isn't fast enough, but Mach-5 or 6 above 100kft starts to really shrink the size of the orbiter needed. Note again that I want a vehicle that holds either crew or cargo; imagine if the present day Shuttle didn't have to lug that inch-thick aluminum cabin, how much smaller would the whole vehicle be?
I maintain that it would be quite difficult but not impractical with today's technology to build such a thing (without getting too big), but a little advancement in technology could make a big difference here. Slushed hydrogen spiked with chlorine or aluminum with carbon nanofiber composite structures and so on (or if someone figured out how to make a cyclic ozone catalyst) would make a big difference, since it would substantially shrink the fuel tank volume.
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A cylinder-shaped scramjet just seems to have limited application to me, since the air has to be hitting it straight on for it to work, but you don't get that if the engine is tucked under the shock-front of supersonic flight. The Navy's Trident-II missiles use a extendable nose "spike" to generate a shock front that the rest of the missile "hides" behind to reduce drag infact, since the rushing air flows around rather then against the nose.
I was thinking like strap-on scramjet boosters like the Delta-II/IV and Atlas-V SRMs or the Delta-IV HLVs side boosters, but they won't work very well if they are "behind" the shock front from the nose, nor will they burn very long if its a true rocket, since it leaves the atmosphere quickly.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Which brings me back to what altitude is the atmosphere unuseable for scramjets and can we obtain the orbital velocity before reaching this point using this technology making the need for another stage either small or not needed.
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A scramjet all the way to or near orbital velocity is probobly a little beyond our technology level right now. As nice as it is not to have to bring along oxygen or all your reaction mass, Hydrogen doesn't burn hot enough nor can the vehicles' skin survive air friction heating with passive thermal protection. You've got to hit about Mach-20 to make the final orbital push easy for rockets.
If there were some way to work these "simple" scramjets into a launcher like, say, the Pegasus that might really boost their payload considerably, while still being a relativly small/cheap/easy launcher.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Say you had a rocket somewhere between PegasusXL and Delta-II, mounted under a large cargo jet...
The rocket would be in two (or two and a half) sections, the forward end would contain one of these "simple" scramjets, fuel for the engine (hydrogen, methane), and associated pumps.
The rear of the rocket would have a simple conventional liquid rocket, preferably with a reasonably high specific impulse, and restartable. The payload would ride at the front of this section.
The assembled vehicle would be dropped and the chemical rocket ignited until scramjet ignition speed, where it would accelerate to a fairly high mach number (12-15) and shut down. Then, using some means to effect seperation, the complex scramjet section would eject and reenter before achieveing orbital velocity, so a heat shield would be easy.
Then the chemical engine would reignite to go the final ten or twelve mach numbers and drop the payload (with its circulization kick stage) into orbit/transfer orbit.
Edit: ...hmmm. Rigid metal scramjet section, preferably fueled by Methane, or Hydrogen if nessesarry. The rocket section would be pressure-fed Methane to hold down the volume, with two seperate pressurization tanks for two ignitions. Carbon composite would be ideal here.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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The first applications of Scramjets will be military. Long range sonic to hypersonic missles of all sorts will almost certianly be the first applications of such a system. The reasons are pretty simple. Smaller engines for these missles are much easier to design and the potential military payoffs are enormous. Scramjet missles could bring incredibly enhanced range and speed to missles of all sorts. We aren't quite there yet, but my money is that scramjet missles and unmanned drones will dominate the next generation of aircraft. Their introduction makeing our 5th generation fighters and BVR (beyond visual range) missles as obsolete as these fighters are making our current 3rd and 4th generation fighters obsolete.
He who refuses to do arithmetic is doomed to talk nonsense.
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Some food for thought.
Air fuels spacecraft
An airborne atmospheric oxygen liquefaction system that would fuel an air-launched vehicle in spaceflight to produce liquid oxygen on the carrier aircraft by cooling ingested atmospheric air.
Empty tank being filled as you go...
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All these Rube Goldber LACE sytems give you is complexity and headaches. All in a vain attempt to lower oxidant weight which isn't a big deal. Just make a big simple rocket and be done with it.
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