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A Million Bucks, Mach 7.6, Straight Down
Dspiral writes "At the Canadian publication, The Globe and Mail, they
write about the scramjet.
A jet engine, with theoretical speeds over 8000 Kph, and pollution free!" Zero pollution because its fuel is hydrogen
(a scramjet
takes its oxygen from the air).
The HyShot homepage
is amazing; the beast has been built on a shoestring, barely over a million dollars Australian, and my favorite part is their planned test:
"...shooting an engine into the atmosphere on a rocket, and hoping it will ignite as it plunges back down to Earth. Mr. Paull's speed objective is Mach 7.6, and the engine should ignite 23-35 kilometres off the ground."
Glad to help debunk that lose use of terminology. The SR-71 propulsion system really contains two Pratt and Whitney J-58 turbojet engines. Now, keep in mind several things: first of all, the flow at the jet engine face must be subsonic. To date, no operational gas turbine engine has supersonic axial flow through it. So all of today's gas-turbine engine'd supersonic planes have an intake system that sets up a shock system to make the flow following the last shock (a "normal" shock) subsonic. This is the flow the engine face sees.
The SR-71 incorporates what's called a mixed-compression inlet, that is the _external_ big (movable) cones do some of the compression, setting up a conical shock wave, and then an _internal_ "shock train" (several small "linked" shock waves) inside the inlet lip do the rest of the slowing down and inlet flow compression to subsonic. Now at full speed, the SR-71 is operating with the J-58s in full afterburner. The "ramjet" designation comes from two details.
One is that at full speed, a good portion of the air that passes through the inlet then gets ducted directly to the exhaust nozzle -- but this air has already contributed to the thrust because it is part of the high-pressure stream pushing on the back of the inlet cone (higher-pressure against aft-facing area is thrust, boys and girls).
The other detail is that the J-58 engines have big tubes that at high Mach, bypass a lot of flow past the high-pressure compressor stages and directly to the afterburner. This bypassed air doesn't see a turbine, so it's "like" a ramjet in that sense. But because the majority of the flow at least passes through the gas turbine engine's compressor and afterburner, it's not a "true" ramjet.
You are correct regarding subsonic operation of ramjets. What differentiates the two is that scramjets have supersonic flow all the way through the engine flowpath, whereas scramjets turn their flow subsonic before combusting it. Both engines use the exact same principle for air compression -- setting up a shockwave system that the air passes through. As the air passes through the shock wave, it slows down and its static pressure goes up. The ramjet must have the flow following the last shock be subsonic, whereas in the scram it is supersonic. However, the air gets slowed down in both cases (if it didn't, there would be no compression).
:)
While an engine that could do ram/scram certainly would have a larger operational flight Mach number range, it wouldn't be able to get off the ground on its own (i.e. no static or subsonic thrust). Research has indeed been done on combined gas-turbine ("conventional jet")/(sc)ramjets (known as "combined-cycle" engines), and that kind of beast could potentially have the the full envelope capability. Also, don't confuse the SR-71's so-called "turboramjet" as being a combined-cycle engine. It doesn't have a true ramjet-type flowpath, and the compressor would start to melt if the flight speed reached "true" high-speed ram/scram speeds.
All this kind of talk, though, is sort of pie-in-the-sky and ignores the fact we've still not yet demonstrated a free-flight scramjet-powered vehicle. That's what NASA's Hyper-X project is supposed to address. You can get more info on Hyper-X via http://www.dfrc.nasa.gov/
BTW, as you might have guessed, IAAE (I am an Aerospace Engineer)...
Isn't that what Michael Knight turned KITT's engine into in that episode of Knight Rider when they got stuck in the dessert?
--
A buddhist walks up to a hot dog stand and says ``Make me one with everything.''
IANAAE (I Am Not An Aerospace Engineer) but IIRC (If I Recall Correctly), a huge proportion of the fuel used to put a shuttle into orbit is used in the first mile or so, getting up to the speed of sound.
/. article).
This is why NASA is working on a launch system that runs on an inclined rail using electromagnets. (from a past
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
Ramjets and Scramjets were used chiefly in surface to air interceptor missiles of the 1960's and 1970's. For taking out high-altitude bombers and supersonic attack planes.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
They're more than acronyms now, they're web cliches. Had to use em. But didn't want to risk the inevitable 30 or so postings afterwards asking "what does IANACN stand for?"
I Am Not A Clueless Newbie.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
It follows that ultra-light rockets that can achieve orbit would be practical, using this kind of technology.
Second, it -ALSO- follows that giant rockets, capable of putting entire large-scale constructions into orbit, would be practical, as it would be within the sorts of costs you expect for modern rockets.
By implication, if the Oz engine works, you could start seeing groups of High Schools (with a bit of sponsorship) lobbing entire space-stations into orbit, rendering the ISS completely worthless.
(Which, to be honest, is an accurate assessment anyway.)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Unfortunately, this method produces gas-state hydrogen. The liquifying process requires energy also. I know a slick way to do this with water power, but it's not very efficient...
-- Jeff Paulsen
I haven't tried this myself, but here goes. It should work for liquid air (mostly nitrogen), but the principle should hold for hydrogen as well. Take a pressure-safe vessel and put it in the creek. Take a paddle wheel and put it in the creek. Use the wheel to compress your gas-state hydrogen into the pressure vessel. This heats the hydrogen, but the heat is lost into the running water. When the vessel is full of high-pressure room temperature hydrogen, bleed the hydrogen out through a small valve. Hydrogen expands, cooling as it does. Liquid hydrogen then drips from your valve, with extensive loss to the air.
Pretty crappy, eh? But for liquid air, the loss doesn't matter much, and all you had to do was go down to the creek.
Feel free to tell me why this won't work, if anybody knows a reason.
-- Jeff Paulsen
Ok, is it me or does this planned test sound like an Urban Legend in the making.
-The JungleBoy
--
"You never know when some crazed rodent with cold feet
might be running loose in your pants."
"You never know when some crazed rodent with cold feet might be running loose in your pants."
-Calvin
Hydrogen can be obtained from non-polluting sources of power such as solar. But it would seem that a hydrogen-burning engine is going to produce some oxides of nitrogen, as long as you suck an oxygen-nitrogen mixture (air, of course) into the engine.
There was a Canadian comedian (I forget who) I heard on the "This American Life" radio program saying that Canadians cannot let a comment about space flight pass by without saying "Canadian-made robotic arm! Canadian-made robotic arm! We made that arm!"
And what do you think happens to that oxygen it takes out of the air?
Answer: it combines with the hydrogen to become water vapor, which then falls on the ground as rain, where it sustains plants, which are busily converting carbon dioxide into oxygen.
As for "hundreds of rockets smashing through the stratosphere a day", compare the cross-sectional area of a rocket with the "surface area" of the stratosphere, say "gosh, that's a tiny ratio" and then stop to think how much worse all the petroleum fuels burned by airplanes are for the atmosphere.
Hell, next you'll be worrying about the fact that every launch slows the rotation of the Earth.
-
This is somewhat old news. Now call me a conspiracy theorist, but I honestly believe the US govt has had atleast one of these types of aircraft for quite some time now.
In the 90's, Reagan started the Aurora Project which was to create a hyper-sonic plane that could go from NYC to Tokyo in under 2 hours. The engines were scram jets.
The project was never really heard of since then, but oodles of initial money was dumped into it. Also, the US' fastest airplane, the SR-71 has since been retired with no replacement (some say that satelites make high/fast flying planes obsolete). IMHO I think we have a couple of these jets being used in our military.
I'm pretty sure I've got my facts straight on this. Anyone else heard of this?
"Woomera is right in the middle of nowhere so it's a bit hard to hit anything."
...
"Now it's used as holding area for illegal immigrants..."
Sooo... it's a bit hard to hit anything but illegal immigrants? Check.
Kevin Fox
--
Kevin Fox
Laiks was the first cosmonaut. :-)
Science, like Nature, must also be tamed, with a view turned towards its preservation.
Ramjets may be; scramjets I doubt, as there is no self-sustaining, thrust-producing scramjet in operations, AFAIK. Little problem with trying to combust air while it's travelling higher than the speed of sound (and thus pressure waves, and thus flames) of the medium combusting.
Solar cells are a type of semiconductor. And we all know how clean and pollution free the semiconductor manufacturing industry is. Pollution free, hah!
Ryan
The X-15 wasn't a jet. It was a rocket. Air launched from a B-52. They have one at the National Air & Space Museum. Seriously cool looking.
Best Slashdot Co
Yes. You can burn hydrogeon fairly easily on the ground and despite atmospheric conditions, the speed at which the aircraft is travelling actually creates enourmous pressures (and ammounts of O2). The problem with scramjets is that like their cousins ramjets, they must be taken to very high speeds before the engines can operate. Those speeds are estimated at around Mach 2 to Mach 4. This is because, the compression is achieved not with a turbine (as in a traditional jet) but with the velocity of the incoming air.
Someone you trust is one of us.
Wow, I'm not sure how this got pegged as a troll. It was supposed to be funny. Sorry if I contaminated the screenwaves. That goes for the other one too. That was just slashdot not reloading when I clicked the button.
One thing you need to add: Things like Ozone and nitrogen oxydes aren't created by the fuel itself, but by the heat involved in the combustion. It's likely that a Hydrogen engine will still produce this kind of pollution.
Opus: the Swiss army knife of audio codec
Stupid sexy Flanders.
Because of the slightly different climate, Canadians have a tendancy to take the probability of environmental extremes more seriously. +40C~-40C is supposedly considered US Mil Spec (104F ~ -40F). In Canada, it's considered outdoor equipment. I can exceed those exremes in one year driving around Alberta. Most years I can get +30~-40 just planting it in my backyard in Edmonton.
A friend ofmine has a story of some oilpatch equipment that froze up while stil inside of it's rated spec (rated to -45C; froze at -37C). He called down to the Texas company that supplied it to complain. The answer:
----In any event, there isn't a whole lot of conspiracy theory around the Avrow. The generally accepted theory is that the US needed many of those hot engineers for the Apollo project. That's where many of them went when the Arrow was tanked.
You didn't think that the States could get all the way to the moon without foreign help, did you?
As to the Avro enginering data being destroyed, it makes complete sense to me. The system was capable of doing stuff that the US was either incapable of, or unwilling to acknowledge being capable of. With most of the engineers going over to NASA associated work, the project was going to be, at best, mothballed for a long time. The last thing that you want is to have all this engineering data stacked in a warehouse somewhere just waiting for a Soviet Spy to cart it off to the Embassy. Far better to just trash the existing data, and rebuild from scratch later when/if you decide to do it again. Besides -- by the time they'd get around to restarting the project available technology could be expected to have advanced beyond whatever miracles they'd produced back then.
Pretty much the same thing was done with the Saturn 5 engines when NASA decided to go to the Space Shuttle. Although some people feel that it was done to prevent the ability to go back to non-reusable craft, I think that the security explanation is quite applicable here as well.
--
Free Software: Like love, it grows best when given away.
And hydrogen is a pain in the ass. It has a higher specific impulse (thrust per mass of fuel) than any other fuel. That's why NASA is addicted to it. But it's density impulse (thrust per volume) sucks. Plus it's a hard cryogen. So you have to have a BIG, well insulated tank. That translates into major weight and major drag. This is OK on the ground, but it's really not such a great aerospace fuel. NASA insists on using it, as far as I can tell, mostly for reasons having to do with internal politics and organizational culture. (The Russians use kerosene or alcohol, which don't have as good a specific impulse but have a much, much better density impulse.)
"Research is what I am doing when I don't know what I am doing." -- Wernher von Braun
Depending on how high up the rocket sends it, it could easily, with an apogee of, oh, say, 1.6 million feet, attain a speed at reentry (300000 feet, or about 100 km) of 24,400 feet/second, well over mach 20-something (I just ran my code for those numbers for something completely different, how coincidental!).
Then, of course, it will heat up very rapidly and ablate. The point is, speed is not a problem, but materials may be.
SDMI: Finally! Music that won't rip or burn! Brought to you by the fine folks at RIAA.
You're right. As the object falls into the atmosphere (300 kft is above the sensible atmosphere, and right on 'the edge'), the dynamic pressure increases and drag goes with it, slowing the vehicle down until it 1) reaches terminal velocity, or 2) slams into the ground. What I am flying slammed into the ground at 20000 fps. I looked at the picture of the hyshot on the webpage and it reaches apogee at just over a million feet. This means it might have a max v of about 18000 fps or so. Then it starts slowing down. When it hits the desired speed (I am sure it isn't as low-drag, or high-beta to be pedantic), it flicks on the jets and uses that to basically overcome the effects of drag.
They are claiming a sustainable velocity of Mach 7.6 or so, so you are correct. It would be prohibitive to expect Mach 20, but the fact is, it may pass through that velocity. The higher they go, the harder they fall, and velocity in a vacuum is only a function of potential, that is v= const* sqrt(h), h being height at apogee.
SDMI: Finally! Music that won't rip or burn! Brought to you by the fine folks at RIAA.
big deal
I am become Troll, destroyer of threads
As a canadian, that was my first thought...
I am become Troll, destroyer of threads
I remember an old story illustrating the differance a 50 or 100 year gap in technology makes. It was based on the idea of someone from 1920 trying to cope with a jet engine from 1970 drone with semi conductors, etc. interesting stuff.
just goes to show you what progress has been made
"It is a greater offense to steal men's labor, than their clothes"
Dude, the first rule of Flight Club is: Never talk about Flight Club! You also forgot the second rule of Flight Club, which is: Never talk about Flight Club.
A couple of people have mentioned the Arrow, presumably because this article appeared in a Canadian publication. However, it should be noted that nowhere does it mention any Canadian involvement in this scramjet research.
Also, I think comparisons with the Arrow are not very valid.
The Arrow was not a research project on new technology, it was an engineering project to produce a working fighter incerceptor that can enter active service.
It was a military vehicle, which meant that the market for it was relatively small. Furthermore, the Canadian requirements on the aircraft were so specialized that nobody else in the world was interested in such a beast.
On the other hand, the market for a working scramjet vehicle would probably be huge.
I'm not going to start speculating why the Arrow project was nixed, because that would probably ruffle a lot of Canadian feathers and start a flame war (it's probably Canada's biggest conspiracy theory).
Personally, I don't find it fishy that they cancelled the project; I do find it fishy that everything related to the project was destroyed.
--
Accountability on the heads of the powerful.
Power in the hands of the accountable.
Would it be possible to strap a couple ScramJet engines to what is essentially a 'large-ish' and appropriately desgined 'airplane' and fire up a couple solid fuel rockets to propel the bastard into space?
Someone tell me these engines will enable the takeoff of a 'Personal* Space Plane'?
*I realize they wouldnt be TurboProp Planes like the local Flight Club - but I do mean a 'personal sized' Space Plane....
How does MACH7.6 compare with the the speed necessary to escape the atmosphere and head off into space? Obviously I realize the mass of the vehicle is relevant. What Im getting at is would it be possible that this technology could lead to what Im describing?
Pollution free? Maybe air pollution free, but I doubt that it is noise pollution free! At least it will fly so fast that you won't hear it for long, and by the time the noise hits, it will be long gone.
Keeping
NASA is run by the US government. Of course they are going to have troubles
Actually, just because one group is having problems doesn't mean that another group will not be able to approach the problems from a fresh perspective.
I think this is an excerpt from the Southwest Airlines business model.
The X-15 plane (scroll down the page for program history), which flew for the first time in 1959, exceeded Mach 6, and flew over 100,000 ft.
The project was eventually cancelled, after a combination of spectacular crashes, exceedingly high costs, and the success of NASA's programs.
It is interesting that the X-plane pilots viewed themselves as the true masters of high-altitude and space flight. In their opinion, they were in control of their missions from start to finish, unlike the Mercury astronauts, who were simply strapped down on top of an explosive bottlerocket. Indeed, the first astronaut was a chimp!
Bob
Science, like Nature, must also be tamed, with a view turned towards its preservation.
Little thing, but Ramjets definitely don't produce subsonic thrust. No moving parts, so without a strong compressed air input there's not a whole lot they can do... They're restricted to Mach 2 ish and above, too.
I was trying to find something on Google to back this up - hit Roger Ramjet instead :) Try http://www.britannica.com/bcom/eb/article/6/0,5716 ,64186+1+62599,00.html?kw=ramjet instead.
Greg
(Inside a nuclear plant)
Aaaarrrggh! Run! The canary has mutated!
It's a good thing we're dumping all that CO2, then, so that the plants can get carbon to build roots to gather H2O which they can convert (together with the CO2) into hydrocarbons and free oxygen.
Save the environment! Burn coal today!
---
Did you notice the careful wording of the SR-71 description?
"The fastest known aircraft was the U.S. SR-71 Blackbird..."
Liquid Hydrogen does not occur naturally here on earth. The most natural state of hydrogen is as a component of water. And when it's burned it turns back to water. Even with a 100% efficient process it takes as much or more energy to create liquid hydrogen as the liquid hydrogen itself has the potential to create. Therefore it's not polution free, the polution is simply pushed off to some other source that generates the hydrogen, such as a coal, gas, or nuclear power plant.
So I wish I could stop hearing how burning liquid hydrogen is our savior as unlimited pollution free energy.
-- Greg
Slashdot, would a spell-checker for posting be too much to ask? It's not rocket science!
They also claim that they have set the world speed record for a chamaign cork (40 km/s) here (bottom)
If Godzilla did not exist, man would have had to create him.
It will.
Really.
There is a lot of it, surely. But when you get into the stratospheric levels there are delicate layers up there. The ozone layer is not just a simple 2 atom thick layer of ozone, there are support layers of other gases that help to keep it stable.
I agree, this technology is vastly superior to using fossil fuels for transportation purposes.
I simply hope that they work out the bugs and take the climactic effects into account, so the cure isn't worse than the disease.
Yes we have rockets all the time, but this is a question of scale. We do not have hundreds of rockets smashing through the stratosphere a day.
Goat sex free since 2001
One example of Canadian engineering abilities might be found in some of the sites regarding the ill-fated Avro Arrow, like here and here. Some of the things achieved with this experimental craft have never been duplicated, and unfortunately the project was only destroyed due to political reasons. It could be said that while the U.S. does have great research abilities, in some areas the U.S. can learn from their Northern neighbours. After all, even NASA is still using the Canadian-made robotic arm on the space shuttle.
You can accomplish anything you set your mind to. The impossible just takes a little longer.
On top of that, the article is so short on facts (not even any links to more information in the article body - don't these nitwits understand what hypertext is about?) that it's hardly worth reading. News for nerds? I think not.
--
Knowledge is power
Power corrupts
Study hard
Time is Nature's way of keeping everything from happening at once... the bitch.
It means that the combustion occurs above mach 1. A normal ramjet is quite capable of operation above mach 1. However, the incoming air is slowed down and pressurized before combustion. In a scramjet, the air is still moving at supersonic speeds relative to the combustion chamber and fuel injectors. I've seen trying to keep a hydrogen/gasoline/whatever flame alive in those conditions (at the qantities of fuel burned by standard jet engines and more) compared to keeping a candle lit in a hurricane. It's difficult. No, REALLY. The benefit of a scramjet is that it can operate at REALLY high speeds. A ramjet loses too much energy slowing the air down to work above about mach 3-5. The concept is *similar* but fundamentally different.
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
Conventional turbine engines can of course be used, but they don't really like getting all the way up into the scramjet operating range. Thus, there has been a lot of research into engines that can work both as ramjets (subsonic combustion) and scramjets (supersonic combustion). Whereas they would still need to be moving around Mach 1 before they can start operating, it means conventional engines would be used for less of the flight, OR that the use of rocket combustion (bring your own oxygen) for the initial part of the flight without a serious weight problem. After all, the whole point with this whole thing is to avoid the rocket weight problem of having to bring your own oxidizer and just use the O2 in the air. Since for an H2-fuelled engine the oxygen is 8/9 of the weight, the advantage is obvious.
(Did I mention that I really hate that Slashdot don't let you use <SUB> and <SUP>?!?)
Call me crazy (go ahead, do it) but I see a rocket going up really fast, turning over, coming down really fast in order to build up the speed to go down even faster (2 kilometers per second) and then it hits the ground (or whatever). Isn't anyone concerned about a system that has no uplink at all, using only internal instruments for navigation, with this kind of power? There's no way to turn it off once the launch pad umbilical is cut, and even if things go right, 2km/sec is faster than anything else I've ever seen hit the ground. Even the terminal velocity of meteors is often slower, because they aren't falling and pushing at the same time.
I'm worried, but I wanna see...
Kevin Fox
--
Kevin Fox
"Thank God it landed in that smoking crater!"
"Prefiero morir de pie que vivir siempre arrodillado!"
--