X-51 hypersonic scramjet test: Flameout at Mach 5? US government aerospace agencies have achieved the world's first hypersonic scramjet flight using hydrocarbon fuel. The test did not go perfectly, but further flights will follow; organisers said they were "ecstatic" with progress thus far. Concept graphic of the Waverider in flight, during rocket boost. Credit: AFNS …
Didn't Barnes Wallis forsee this sort of thing years ago - IIRC a flight from London to Oz in about two hours? Remember seeing a programme about his work on the telly in the 70s or early 80s and showed his design for an 'aeroplane' to undertake such a flight. If IIRC also the 'plane had very slender wings with the engines mounted towards the tips of the wings.
The original design of Concorde was for two of its four engines to be ramjets, which would have given it incredible range and fuel economy. That plan was scrapper in part due to a new Labour government at the time. Make's you want to weep, eh?
(Paris, cos I bet she'd never scrap a ramjet)
If you listen to the You Tube video, the X15 project had started this effort. However the materials required to handle the heat and stress didn't exist.
Knowing how something might work and having all of the requisite technologies working and available is another.
Thumbs up because this is really cool. If they can work out the kinks, it would mean cheaper access to space.
Don't ramjets occasionally "unstart"? And isn't that a potentially nasty situation? Ask a Blackbird pilot. I for one would never have flown on Concorde if it was fitted with ramjets.
Oh and as for the Labour government, you must remember it was none other than that shuperior shocialist Tony Ben who kept Concorde going whenever it looked like the project was going to die. He it was who made sure both sides agreed to a no pullout clause in the contract. Even on silly little arguments like the letter E (the french wanted it, the brits didn't) it was TB who came up with a compromise.
"If you listen to the You Tube video, the X15 project had started this effort. However the materials required to handle the heat and stress didn't exist."
It would seem you are unaware that the X-15 flew 199 times. It hit M6.15 (on pure rocket power). It was *designed* to study the *problems* of prolonged hypersonic flight. To do so it used a thicker (but not *much* thicker) skin than conventional aircraft in a high temperature Nickel alloy (rather than aluminium) to act as a heat sink in a "hot structure" design concept.
Getting to M6 or 8 has *never* been a problem. Doing it with oxygen from the *atmosphere* has taken 6 decades to get to a flight vehicle.
And it *still* can't do so from a standing start.
Knowing where to put the sensors and knowing what the sensors will say are two very different things. They will have created computer models of the craft before building the real thing, which will have given them an idea of where potential problem sites and useful areas to monitor will be; what it won't tell them is what actually happens there. The sensors will tell them how close their model us to reality. With the new data they can improve the model and use that to inform the next round of physical tests, thus improving the actual machine.
The first time someone looked at Saturn they had no idea what they would see, but they still knew where to look. This is the same principle.
The obvious move here would be to take off on rockets, briefly boost to scramjet speeds, then cutover to scramjets for the trip to the edge of space and finally go back to rockets for orbital insertion.
That way you'd only need two sets of engines, the rockets and the scramjets and you could do away with all the problems associated with the transition between the performance envelopes of turbo/ram/scramjets. An external droptank containing the fuel/oxidiser for the first rocket burn should solve any fuel capacity problems associated with the takeoff side of things.
An external oxidizer droptank would be huge, and the whole point is to get a spacecraft into space WITHOUT dropping large parts of airframe.
Jets kick rockets into the dust for lifting capacity because the oxidizer is ambient and does not require acceleration or carriage on the craft. This is an inherent limitation. You can carry a lot of jet engines and fuel for the volume and mass of an oxidizer tank.
"An external oxidizer droptank would be huge, and the whole point is to get a spacecraft into space WITHOUT dropping large parts of airframe."
I think you'll find he was proposing a *pair* of drop tanks, oxidiser and fuel, to bring the vehicle up to ramjet (or rather scramjet) ignition speed.
"Jets kick rockets into the dust for lifting capacity because the oxidizer is ambient and does not require acceleration or carriage on the craft. "
No. Modern good turbojets (something like those on the JSF or Eurofighter) achieve T/W of 10:1.*Poor* rocket engines hit T/W of 40:1. *good* hydrocarbon fueled ones hit 100:1.
A *true* bill needs to take into account *wings*,inlets and landing gear. Thrust on aircraft is *typically* 1/3 of takeoff weight. On the Virgin jet powered round the world aircraft it was 1/9. With *anything* but a rocket wings (and *all* their mass) are *essential* rockets don't need them.
BTW 1 cubic metre of Liquid Oxygen is *roughly* equal to ingesting 700 cubic metres of air.
Now you were saying what exactly?
To get into orbit, you need to be at 400km and flying at 28000km. Therefore, flying at 20km and 6000 doesn't help you much. In fact, the scramjet engine would be dead weight.
This is entirely a military stuff. Or pure curiosity.
Sorry to spoil the dreams. I'm going to get a beer.
Sure, you can learn a lot from failure, _if_ you have something to examine, but the plan all along was to destroy the vehicle entirely at the end of the flight, so if their sensors were in the wrong place then they will learn nothing. And if they knew where to put the sensors in the first place, then they probably didn't need the test flight.
The whole oxygen argument could also be made with a launcher that is lifted by a U2-type aircraft (extremely long winspan/high altitude capability) to about 20000 meters and then the "conventional" rocket would be ignited to shoot the thing into orbit.
Above 20000 meters (60000 feet) there is not much oxygen left....
Anyway, it will be difficult to challenge the tried and tested, cheap Russian throw-away launchers.
What happens when aerospace guys do economics arguments can be seen with the space shuttle - much more expensive than the conventional way of doing things....
...of what happens when a budget is slashed and when an airforce insists on a cross range capability. NASA had to agree to the Air Force request to get some money out of them.
The original design prior to the cuts was way different to the finished product. It was supposed to haver smaller wings and sit on top of a booster, not strapped to a tank as if it was humping it...
I can't see turbojet -> scramjet being a particularly pleasant (or survivable) experience for a squidgy human. Then there's the whole issue of materials science - throw away experiments (as impressive as this one is) are one thing, having a boat that can fly mach 5+, be refuelled and turn around for another sortie without bits (like engines, wings etc) falling off is another.
The friction on that thing must be crazy. I know it's not quite in the region of atmospheric re-entry, but it ain't *that* far off.
I don't imagine ejection would be that healthy an option either!
Hope they (as in America) don't think that using it as a cruise/exocet type missile is a good idea tho. You can imagine the news story already - "an American missile today destroyed a terrorist training camp killing 80 combatants. On its path to its target its shockwave destroyed 14 schools and 3 market towns killing 1500 civilians. Officials said they were 'looking into the matter'".
"...Something then occurred that caused the vehicle to lose acceleration....."
My guess is either a very (very, very...) high-flying bird strike, or the hypersonic vehicle cabin crew decided on a go-slow.....
Paris, because I think she'll be a great contender for the 'Mile-High AND Mile-A-Second' club....
" either a very (very, very...) high-flying bird strike"
Now please point me to the wiki entry of the 20000 meter-high flying bird. I remember reading that 12000 meters is the record for birds.
More likely a piece of shit falling down from ISS. Or maybe just a malfunction of the experiment. Which is OK, if I compare it with the contraptions I daily create. They normally don't work at all on the first run :-)
"we sort of wanted to re-use the crews. Didn't always work out that way but that was the plan."
I haven't researched it, but my feeling is that the Russian throw-away booster tech has a better record of "reusing" humanoids traveling in spacecraft than the Shuttle. Maybe that is because everything is just so much simpler than the shuttle ?
The only main usefulness of the Shuttle is the ability to steal a Russian sat for the USAF. Go figure the politcial implications of that....
According to Wikipedia (http://en.wikipedia.org/wiki/Space_accidents_and_incidents):
"About two percent of the manned launch/reentry attempts have killed their crew, with Soyuz and the Shuttle having almost the same death percentage rates....
In total, Shuttle accidents have claimed the lives of fourteen.
Soyuz accidents have claimed the lives of four. No deaths have occurred on Soyuz missions since 1971, and none with the current design of the Soyuz. Including the early Soyuz design, the average deaths per launched crew member on Soyuz are currently under two percent. However, there have also been several serious injuries, and some other incidents in which crews nearly died."
The apparent discrepancy in death rates is explained by the fact that the Shuttle flights generally carry more people, so the same number of fatal flights (2) results in more deaths.
I'd say neither system has a statistically significant edge in safety, partly due to the fact that we're only talking about ~240 flights (~130 for the Shuttle, ~110 for Soyuz) over the past 40 years.
When it comes to putting a human in it, it doesn't matter how fast it ends up going - the important bit is how much acceleration you experience.
Let's say you're dropped from a parent aircraft at 36,000ft at 150m/s (335mph). According to Wikipedia, Mach 1 is 295m/s at 36,000ft. If we assume most humans can tolerate 4G with reasonable discomfort, then we want to be accelerating upwards at 3G. If we want to end up at 20G (2950m/s), we need an extra 2800m/s. 1G=9.81m/s/s, so with continuous at 3G acceleration, that only takes 95s. Which is perfectly acceptable. Dial this back to 3G on the people inside, 2G aircraft acceleration, and you're talking 142s.
As for ejection, they figured that out ages back for the F111. You don't eject the pilots individually in their seats and faff about with canopies and stuff like that. No, you just blow the whole front of the plane off, because it's already a nice strong armoured unit designed to protect the pilots. Then the whole thing floats down on a chute like a space capsule.
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Dyson could do better :).
On a serious note - why use fuel when they could just do all the computational processing on a group of nvidia GPU's and and run the heatsinks into the expansion chamber to use those to heat thinks up. Would be one solution to passive cooling GPU's :D.
What next - sensors that detect the thermal boundiaries and ride between those.
Another thought - how small can these be scaled down - but guess would end up using the expansion chamber as the main flight winds on that scale.
ANON for the bad comedy
"I can't see turbojet -> scramjet being a particularly pleasant (or survivable) experience for a squidgy human. "
Acceleration is *not* velocity. Provided the environment system is up to the job (and that's a pretty *big* if) the crew won't have a problem.
Then there's the whole issue of materials science - throw away experiments (as impressive as this one is) are one thing, having a boat that can fly mach 5+, be refuelled and turn around for another sortie without bits (like engines, wings etc) falling off is another.
Correct.
The friction on that thing must be crazy. I know it's not quite in the region of atmospheric re-entry, but it ain't *that* far off.
Actually it's *very* close to re-entry conditions in terms of heat input per unit area, *especially* in the intake area. Proposed solutions included ones proposes to cool the Shuttle wings on reentry.
I don't imagine ejection would be that healthy an option either!
As pointed out a self contained crew capsule would be the proffered option. BTW the F111 capsule had some "issues," concerning misfiring of the guillotine severing the control cables prior to separation. A number were lost over Vietnam before this little fault got found out.
Hope they (as in America) don't think that using it as a cruise/exocet type missile is a good idea tho. You can imagine the news story already - "an American missile today destroyed a terrorist training camp killing 80 combatants. On its path to its target its shockwave destroyed 14 schools and 3 market towns killing 1500 civilians. Officials said they were 'looking into the matter'"
Ballistic flight path. Likely to remain *very* high as long as possible. Inlet pressure is a multiple of surrounding atmospheric pressure. IIRC at M3 it is 37x surrounding air pressure, but at 60-80 000 (roughly SR 71 ceiling) it's roughly 1/16 sea level. Running full tilt at ground level would rupture it unless *ridiculously* strong.
Hypersonic cruise has *some* potential uses. Boosting to orbit (especially single stage) is *highly* speculative.
Mine would have a PMP loaded with "Facing The Heat Barrier" including the history of NASP and its, er, "creative" promoter Anthony DuPont.
Six was the figure. Yes technically it *is* a number but your statement was misleading.
BTW there's a hyphen in F-111. It's an American concept, foreign to the British forces. But then so is the concept of a supersonic swing wing bomber with more range than any other save the B-1.
Farewell F-111s. You will be missed.
Ever notice how for speedy progress we need to be in a war? You know, getting from tri- and biplane to monoplane, getting the engines up to serious capability, jet engines, long range rocketry, getting into space even if that war was mostly fought by posturing and proxy, and so on and so forth. Right now the US is actually slacking because they already have a large fat technical edge over their enemy du jour, and they change enemies too often, so the big advances are in subtly or not so subtly destroying privacy in the name of finding new citizen-enemies to pursue. And in pork barreling for the beltway bandits, of course, but that's a given since we're all well and truly caught in the military industrial complex, currently expanding into security scareware. It's big business.
The thing is, beyond a certain point the earth gets too small to have a jolly old war big enough to advance the current technology in the traditional way.
...that the craft ran to the end of its useful life and, having served its purpose, was allowed to complete its willy-nilly course into the deep blue sea. Meanwhile, back at base, the eggheads are going, "OK looks like something came up about 200 seconds in. Let's take the data back home and see what we stumbled upon." IOW, not preferred but not unexpected, either. Initial tests going awry is actually par for the course (which is why they have a few more remaining). As others have said, simulations can only take you so far; eventually you have to just get out there and, well, blow stuff up.
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