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First Ever Scramjet Reaches Mach 10
stjobe writes with the news that a group of US and Australian scientists successfully tested a supersonic scramjet engine in the Australian Outback on Friday. The Sydney Morning Herald reports that a rocket carrying the engine reached mach 10, and climbed to an altitude of 330 miles before the apparatus re-entered the Earth's atmosphere. "Australia's Defense Science and Technology Organization (DSTO) said it was believed to be the first time a scramjet had been ignited within the Earth's atmosphere ... Scramjets are supersonic combustion engines that use oxygen from the atmosphere for fuel, making them lighter and faster than fuel carrying rockets. Scientists hope that one day a scramjet aircraft fired into space could cut traveling time from Sydney to London to as little as two hours."
What about the X-43A? It also ignited successfully and flew under power.
http://en.wikipedia.org/wiki/Boeing_X-43
This is cool, yes, but the emphasis on "first" seems a bit off.
From TFA: "Australia's Defence Science and Technology Organisation (DSTO) said it was believed to be the first time a scramjet had been ignited within the Earth's atmosphere."
http://en.wikipedia.org/wiki/Hyper-X
Is there something I'm just not getting here?
How can I believe you when you tell me what I don't want to hear?
"scramjets are supersonic combustion engines that use oxygen from the atmosphere for fuel"
Scamjets use oxygen from the atmosphere as an oxydizer unlike traditional rocket engines which need to carry their oxydizer. Scramjets still need to carry fuel.
No. I am not a rocket scintist.
Holy cow, no it can't! Not only isn't it going nearly fast enough, but the vast majority of that delta-V came from a conventional rocket. The scramjet experiment only operated for 14 seconds.
This is an experiment. Scramjets are still in the "data-gathering" phase, not the "let's make a realistic engine" phase, nor the "let's make a scramjet-powered craft" phase.
Everybody point at the libertarian and laugh.
This event took place in Australia, and was reported by an Australian paper; therefore, it was correctly reported in the metric altitude of 530 kilometres.
So why was the summary changed by slashdot editors to the imperial unit?
Firstly, not everyone who reads this site is American, and secondly, this is an audience of nerds. I think we can handle kilometres! Even the USA's NASA is all metric now.
The scientists who developed this scramjet used metric, the country it was tested in used metric, the newspaper that reported it used metric, so how about we keep it that way?
This is very interesting to read as I just finished reading Ben Rich's book "Skunk Works" where he talks about the SR71. When president Reagan announced the administration's intention to build a hypersonic airplane, he just shook his head. It's simply not practical, with or without the scramjet engine. The SR71 flew at 85,000 feet at about Mach 3.2, and reaches skin temperatures of 2000-3000 degrees (F I presume) just from moving through the atmosphere. Accelerating to Mach 10 would burn up or otherwise compromise any current building material, except for the carbon-carbon and ceramic materials used on the space shuttle's heat shield, but aren't practical for airplanes. So what good is this scramjet, at least as far as a hypersonic airplane goes? Seems to me all this talk of Sydney to London in 12 hours is a bit fanciful. So the question is, how exactly will this engine be used to accomplish this? The only way to reach hypersonic speeds without burning up is to make the trajectory sub-orbital so that the aircraft is in the thinnest atmosphere possible when it's firing it's engines to go Mach 10. But of course there's not a lot of oxygen at that altitude. And to really achieve sub-orbital trajectory you need a rocket engine, not any kind of air-breathing engine. So my questions are: Is Ben Rich right that hypersonic travel is essentially impossible? Will the scramjet help with a suborbital trajectory? I understand that igniting the scramjet is a breakthrough. Jet turbines at supersonic velocity have always been problematic.
Off-topic, Ben Rich says in his book that the codename Aurora that everyone likes to think refers to some hypersonic aircraft, was actually the codename placed on the B-2 project as Lockheed and Northrop were competing for the contract. It's funny to think that to this day, folks still hang onto this and imagine some mythical hypersonic airplane. Which never existed. Or does it?
Holy cow, no it can't! Not only isn't it going nearly fast enough, but the vast majority of that delta-V came from a conventional rocket.
Not only that, scramjets need an additional propulsion system in order to reach working speeds. Usually, yes, conventional rockets are used. This is one of the major drawbacks in these type of designs.
330 miles is approximately 5 times the minimum altitude for entry into "space." The Kármán line is at an altitude of 62 miles (100 km) which is the boundary that defines where space begins. 75 miles is where atmospheric drag starts to have an effect. This means the craft traveled well into the Thermosphere. People who travel above 50 miles are called astronauts by NASA.
Yeah nerds, learn KM, not Miles.
No self respecting scientist or nerd would ever use the word MILES in their own documents.
Slashdot is NOT mainstream, get back to being NERDY!!!
Liberty freedom are no1, not dicks in suits.
for consistency, would you prefer if they used the speed of sound in a vacuum?
Blazing Spiders
I really do hate to nitpick, but the skunk-works are Lockheed Martin, not Boeing.
I'm sure they could develope some insane passenger aircraft, but they need to make money not bleed it. If I came up with a proposal to build basically the concord on steroids I don't think people would buy it. I'd try to sell them more cost effective and reliable planes since that's what they are buying.
It was the same fuel as HyShot, plain old hydrogen (plus oxygen gathered from the atmosphere). This scramjet project was named HyCAUSE and the engine was physically a fair bit larger than the successful HyShot flights by the same team a few years back. The team originated from the University of Queensland moved to the Defence Science and Technology Organisation about a year ago. The next flights are a series of ten over five years under the name "HiFire".
getting these to fly without using a rocket to start it. If we can get it to start from say a mach 2 or better sub sonic mach .9, then this will be feasable for more than just bombs. As it is, the only place that this will be of use is in intercontental bombs (small and cheaper).
I prefer the "u" in honour as it seems to be missing these days.
As the theory of relativity breaks down when someone switches the lights off - as C becomes ZERO.
...Einstein didn't think of that.
Oh no
EMail: 0110001101100010010000000110001101110010 0110000101111010011011100110000101110010 0010111001100011011011110110
This is prime example of technology that has almost purely military applications.
However since that does not excite public positively, they are instead fooling the public talking about civilian use.
What might be possible some day is to deliver a bomb from Sydney to London in very short time. Not human passangers.
The inherent heat problems are about 100 times easier to solve, if you imagine
the payload is 50kg of plutonium instead of 5000 kg of humans.
You seem to be sharing the common misconception that LEO altitudes and above cannot be reached at low speeds.
Dude, you can reach an altitude of 330 miles just fine with a perfectly low speed. There's nothing unphysical about it that requires the invocation of holy cows. It is also true that with the lack of a *horizontal* velocity of about mach 30 (at ~100km, you'd need less if you get as far as 330 miles high), you fall back down (well, not back to the same place, you may have traveled halfway around the world by then, but still, back *down*) like a rock. This is what spaceship-1 did, this is what this experiment did. This is what ICBM's do. This is even what proposed "2-hour-sydney-to-london" flights will do. Speed is only needed to get into low orbit.
They go high, fast enough to stay in space for the duration of cruising their trajectory, without air resistance and at pretty dang fast speed, then they just drop back into the atmpsphere.
Nothing to get overly excited about. The concept was already proven to work, and we haven't reached a point where the technology is generating value yet, so it's all still technological limbo. Not that it wouldn't be nice if it actually got done after 20 years of R&D. Shorter times for less fuel would pro'lly mean many more flights in lifetime of aircraft, less fuel burned, less time-in-air per trip, more in-range accessible destination for carriers and while I haven't the slightest clue as to what operational costs on scramjet-based planes would look like, it would seem to have the potential to cheapen things from where they are today.
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Including airport queues that's only about 5 or 6 hours.
According to wikipedia, (I know), the atmosphere is usually considered to end at 328,000ft. (Karman line)
The Stratosphere goes to 160,000ft. You have to go above 50 miles (264,000ft) to be considered an astronaut, and atmospheric effects are noticeable at 400,000ft during reentry.
How is an altitude of 330 miles within earth's atmosphere ?
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Oddly enough I was looking at a scramjet model at around this time in 1987. Subsequent revisions used less fuel and had other advantages - but while it's relatively cheap to do computer modelling and to build a shock tunnel to test these things at mach 8 on the ground it costs a lot to launch a rocket to get the higher speeds. It's not that surprising that it has taken over 20 years on a shoesting budget in a relatively small engineering department in Australia to get this far and get moved to a better funded organisation.
Scramjets need an atmosphere anyway, just like ramjets and turbojets. That's the whole idea. The air flows through it, fuel is injected into that air and ignited. Trying to operate a scramjet in a vacuum would make as much sense as trying to operate a turbojet there. Pretty much all 3 are the same jet engine, more or less. A turbojet uses a compressor in the front to push the air into the engine. A ramjet relies on the fact that if you fly fast enough to start with, you get air pushed into the engine anyway. (Plus some clever design of the intake so the flame doesn't go in both directions.) But the air is slowed down to a subsonic speed at the point where the fuel is injected and lit. A scramjet is a ramjet where the air does flow at supersonic speed through the engine, so basically it's choked. You can add the fuel past the choke point and, since waves can't move backwards in a supersonic flow, whatever pressure you generate there by burning fuel can only go towards the back engine. The front of the engine can't "notice" the higher pressure in the back half because a pressure wave would have to travel through that air faster than sound speed, which isn't possible. Another rough description would be that a scramjet is like a turbojet with an afterburner, only without the turbojet. (Sorta like the sound of one hand clapping, I guess;) Instead of having the turbojet push air through a nozzle and add extra fuel to it, the engine _is_ the nozzle and the airplane's existing speed is what pushes air to it. So you just add the fuel and light it. It's an afterburner without a turbojet. But in the end all 3 work by the same basic principle: air comes through the front, fuel is added, hot air comes out the back. No air, no flame, the engine stops. The plans to use a scramjet to get to a highe enough orbit or even leave the planet, involve getting enough speed while still having enough air for the scramjet, or as boosters in addition to the normal rocket engines, or both.
A polar bear is a cartesian bear after a coordinate transform.
Scramjets need an atmosphere anyway, just like ramjets and turbojets. That's the whole idea. The air flows through it, fuel is injected into that air and ignited. Trying to operate a scramjet in a vacuum would make as much sense as trying to operate a turbojet there.
Pretty much all 3 are the same jet engine, more or less. A turbojet uses a compressor in the front to push the air into the engine. A ramjet relies on the fact that if you fly fast enough to start with, you get air pushed into the engine anyway. (Plus some clever design of the intake so the flame doesn't go in both directions.) But the air is slowed down to a subsonic speed at the point where the fuel is injected and lit. A scramjet is a ramjet where the air does flow at supersonic speed through the engine, so basically it's choked. You can add the fuel past the choke point and, since waves can't move backwards in a supersonic flow, whatever pressure you generate there by burning fuel can only go towards the back engine. The front of the engine can't "notice" the higher pressure in the back half because a pressure wave would have to travel through that air faster than sound speed, which isn't possible.
Another rough description would be that a scramjet is like a turbojet with an afterburner, only without the turbojet. (Sorta like the sound of one hand clapping, I guess;) Instead of having the turbojet push air through a nozzle and add extra fuel to it, the engine _is_ the nozzle and the airplane's existing speed is what pushes air to it. So you just add the fuel and light it. It's an afterburner without a turbojet.
Downside: a turbojet can start at zero speed, ramjets and scramjets need enough airspeed to start. Hence all these experiments involve booster rockets.
But in the end all 3 engines work by the same basic principle: air comes through the front, fuel is added, hot air comes out the back. No air, no flame, the engine stops.
The plans to use a scramjet to get to a highe enough orbit or even leave the planet, involve getting enough speed while still having enough air for the scramjet, or as boosters in addition to the normal rocket engines, or both.
A polar bear is a cartesian bear after a coordinate transform.
Scramjets look good on paper. The thin air coming in is compressed by a series of standing shock waves. Unfortunately, the geometry of these shock waves can easily be upset by small distortions in the engine, which in turn can lead to changes in the stresses with in the engine, which - to cut a long story short - can mean the engine spectacularly demolishes itself when faced with real bits of atmosphere with unpredictable air currents. I found the flight time in...
http://www.abc.net.au/science/slab/hyshot/default. htm
It may not sound like much, but six seconds is very respectable for a scramjet. Yay!
There is a lot of touting about how this would get you from London to Sydney in 40 minutes and stuff. I am not sure how true or economical this is, even if scramjets can be made safe. When you are flying fast, you can either take your oxidant with you (as rockets do) or you can scoop it up as you go along. Scooping it up as you go along means taking in air that was initially at rest and getting to move at the speed the engine is currently going. As only 20% of the air is actually the oxygen you want, this is not necessarily an effective thing to do. It becomes most effective when the oxidant (oxygen) is a lot heavier than the reductant (fuel - and hydrogen is particularly light), so scooping it up as you go takes a lot off the take-off weight.
The other London to Sydney option is to get just beyond the atmosphere using a conventional rocket, then going ballistic and weightless for the main distance, and re-entering and gliding, a lot like the space shuttle. While being weightless is fun, being weightless for 20 minutes makes most people puke, so a large passenger jet might skip the atmosphere and retain a little gravity. A scramjet might be used for this.
Nevertheless, yay!
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Now, that was an explanation! Right now I regret that I'd already posted to this discussion - I can't use my mod points on you. THANKS.
You can't handle the truth.
Actually, at least theoretically a scramjet would continue to accelerate as long as you have air and fuel. You have enough air you have of that ascent (after that you have the speed anyway), and fuel you'd carry anyway. A rocket carries its fuel too.
That's actually one thing that makes scramjets tempting: the fact that it doesn't cap lower than that orbital velocity, and it can work with rather thin atmosphere too. So if you can go upwards at all with it, and modify the trajectory to have enough air for more of the time, you can eventually get it to stay up there.
Probably the only thing that _might_ change, if your scramjet doesn't get enough acceleration, is that you shoot it closer to the horizontal than upwards. Well, normal rockets don't really go vertically either. As you've said, they have to end up with that mach 30 horizontal speed. The difference would be that the rocket starts closer to vertical, to clear the dense atmosphere as fast as possible, and bends later, while probably a scramjet would start directly oblique, to make the most of that atmosphere.
Of course, when experimenting to just get the thing sorted out at all, there's somewhat less point in aiming directly for LEO. So probably 14 seconds are enough for experimental purposes.
Also, well, while scramjets are still experimental, ordinary ramjets aren't. A heck of a lot of missiles already use ramjets. E.g., IIRC the Russians were the first to use them on anti-aircraft missiles, but in the meantime almost everyone else does.
So technically we'd already have a pretty damn fast engine to put on an aircraft. If anyone wanted to make a Mach 5 passenger aircraft, that's probably already feasible with ramjets. The reasons why we don't are completely different, and IMHO somewhat unlikely to change because of scramjets.
A polar bear is a cartesian bear after a coordinate transform.