X-43A ramjet

Palomar · 2004-03-25 11:37:49

[http://story.news.yahoo.com/news?tmpl=s … rsonic_jet]Vrrrroooooooom!

*Hyper-X program. They're going to give it another try on Saturday (last try 3 years ago resulted in explosion). Speeds up to Mach 7 / 5000 mph. Not a "strong-suit" topic for me, but interesting.

What, no in-flight movie? Oh...it's unmanned (never mind!). :;):

--Cindy :laugh:

::EDIT:: Shouldn't neglect THIS little item (Bill, can you hear me?):

"Even so, the future of the $250 million Hyper-X program remains in doubt: NASA recently cut funding for more advanced versions of the plane."

*What's next on the chopping block?

RobertDyck · 2004-03-25 14:29:03

Have they established safety procedures to detach the aircraft from the rocket and let it parachute to safety? The aircraft is already equipped with a parachute as its primary means of recovery. The last failure was the rocket; they never got to test the aircraft itself. At the cost of these things we can't afford to keep throwing away the aircraft every time the rocket manufacturer screws up.

::Edit:: The news story says the plane will crash into the ocean when the flight's done. They won't even try to recover via parachute this time?

Ad Astra · 2004-03-25 19:18:04

The problem last time was releasing the booster 20,000 feet lower than the will this time. The computer models predicted that it could be controlled at this low altitude; the flight test showed otherwise.

Even though NASA pulled out of the X-43C follow-on, it is also an Air Force program, and the AF will probably follow through without NASA participation.

RobertDyck · 2004-03-26 19:23:12

If the Air Force continues the X-43C without NASA participation then hypersonic aircraft development can become classified. Anything NASA is involved with must be public domain.

But NASA only built 2 X-43A aircraft, one was destroyed last time. If they destroy the last one this time, how will they fly two more times?

Ad Astra · 2004-03-26 20:48:09

NASA built three test articles that were intended for tests at Mach 7, Mach 7, and Mach 10, respectively. Assuming that the upcoming test goes well, the disastrous first attempt will not have been a big loss. Should this one fail, the third vehicle will probably be flown at Mach 7 or cancelled entirely.

SBird · 2004-03-27 12:49:27

I'm interested to see how this turns out. We'll find out soon enough, the launch occurs at 1PM PST.

Rxke · 2004-03-27 16:49:55

Yiaaah! Great show!

Looks like this is NASA's good luck year! ... If we forget all about the ISS and the Shuttle, errr... nevermind...

Any way you turn this, it seems like it was a great success. Congrats to the guys 'n gals working on the (axed) project!

Now, what's next?

Palomar · 2004-03-27 21:12:08

Yiaaah! Great show!

[http://story.news.yahoo.com/news?tmpl=s … 4&ncid=716]*Yep! Nice little article here. Would have been fun to see it go.

--Cindy

GCNRevenger · 2004-03-27 22:07:08

Next is, the project is quietly handed over to the USAF to build their hypersonic superbomber while Nasa switches into Moon-Mode. It would be a long, long time before Nasa could build a hypersonic spaceplane with the Scramjet anyway, let the air force play with it for a while.

dicktice · 2004-03-28 10:05:22

Too right, GCNR! The time intervals between NASA's (scale model, don't forget) scramjet tests mean unless the design details are released (the way advanced aeronautical data were made available by the NACA, before it became NASA) we may as well plan on using chemical rocketry for the first generation private LEO attempts. But, what a great thing to have got that hypersonic feasibility flight behind us. Just like the latest Mars rover results, regarding seawater. Now our brainstorming can advance beyond the "if it were possible" stage, in discussing future developments.

SBird · 2004-03-28 12:20:34

Personally, I'm kind of happy about the way this has played out as well. The Air Force has plenty of cash - let them shoulder some of the burden of developing technology they wil no doubt end up using.

GCNRevenger · 2004-03-28 13:59:50

Cost of one Spirit B-2A Stealth Bomber - ~$2Bn
Total USAF space budget ~$22Bn
Total NASA budget ~$15Bn

It will be pretty hard to make a Scramjet airplane hit or beat Mach 20, yeah, let the USAF play with it an advance the basic technology first.

John Creighton · 2004-03-29 10:45:31

How long might it be classified for?

Ad Astra · 2004-03-29 22:45:01

Beleve it or not, the military just doesn't go around classifying everything because it's fun. Classification adds 10-15% on top of a project's cost, and hampers the project members from cooperatin with other groups that might be able to assist the classified project. So I'm hesistant to speculate on whether futur Air Force X-43 flights will be classified.

The best we can do to follow this story is by staying informed. The Air Force Research Laboratory publishes a magazine called AFRL Horizons. If you haven't heard of it, get acquainted with it. It's highly technical, but it's the best journal of the cutting-edge research being done by the Air Force with your taxpayer dollars.

John Creighton · 2004-03-30 08:25:13

cool here is the website:
[http://www.afrlhorizons.com/]http://www.afrlhorizons.com/

Palomar · 2004-07-15 06:00:15

http://www.space.com/businesstechnology … 15.html]An update

*They're going for Mach 10 (the mind whirls)...

Caught my attention especially -- says the temperature of the leading edge of this craft is approximately 2400 degrees F at Mach 7. At Mach 10 the temperature would be at least twice that.

"Those blistering temperatures will be tamed by special thermal protection applied to the Mach 10 vehicle, Sitz said. 'The coatings that we are using were sort of a mini-research experiment in itself.'"

Mach 10 = 2 miles per second. My god.

--Cindy

GCNRevenger · 2004-07-15 08:38:36

And how about this to boggle ones mind... to reach ORBIT you have to hit Mach Twenty Five, cooking along in the region of five miles per second... There is a very good reason the Space Shuttle has to carry such a huge tank of fuel, and why Burt's dinky SS1 and dervitives aren't going anywhere fast (literally).

One of the issues that scuttled the X-30 "Orient Express" Scramjet SSTO was heat and drag at high speeds... though there is a solution, its just difficult: pipe liquid hydrogen fuel through lines in the skin of the craft, particularly the leading edge, to cool it off and pre-heat the fuel, thus adding some of the friction energy to the engine's thrust and defeating the drag to a point.

If a Scramjet vehicle can hit around Mach-20, a small rocket burn could take it to orbit, or perhaps if it could reach lower mach numbers could serve as a TSTO spaceplane carrier of less-than-gargantuan size.

Palomar · 2004-07-15 10:20:49

And how about this to boggle ones mind... to reach ORBIT you have to hit Mach Twenty Five, cooking along in the region of five miles per second...

*Hi GCN! Yes, now that you mention it, I do recall that information from some Apollo-related stories/articles I've read.

I'm wondering what's "the cap" for Mach speed *within* the Earth's atmosphere (as opposed to LEO)?

Just wondering. I wish more brainiacs like you would chime in more often! SBird, come back!

--Cindy

RobertDyck · 2004-07-15 10:40:36

Yea! Yippie! Yahoo! I seriously thought the mach 10 flight wouldn't happen, that the mach 7 flight was the last mission of X-43A. This is really good news.

Theoretically there is no cap. As long as you are flying through an oxygen atmosphere you could take it in. The problem is how much that air will heat during intake, and how much hotter can combustion make the exhaust. Gas expansion provides thrust, and gas expansion is directly proportional to increase in temperature above absolute zero: 0°Kelvin or -273°Celcius. At what point will thrust be less than drag caused by the engine intake? Engine designers can give you some numbers based on old designs, but the truth is they're still working it out.

One complication is conversion of fuel into exhaust; the exhaust may be a form that has higher pressure than stored fuel, which adds to thrust. But liquid hydrogen has very low density (large volume) so this factor works against it. Normal jet propellant (JP-1) or rocket fuel (RP-1) is based on kerosene, which can be handled like gasoline at room temperature. Kerosene is very dense (low volume) but doesn't burn as hot or as completely as hydrogen, so the mass ratio of fuel weight vs. thrust isn't as good. The very small fuel tank makes it ideal for lower rocket stages, but the lower engine performance make liquid hydrogen better for upper stages. But what about an air-breathing jet engine? Isn't that the ultimate lower stage? Expansion of fuel into exhaust by chemical conversion instead of just heat is much better than liquid hydrogen, and the fact that oxygen isn't carried makes it more dramatic. The problem is how to get a kerosene based fuel (JP-1 or RP-1) to burn quickly enough to produce thrust before the supersonic airflow of a SCRAM jet engine blows it out of the engine. JP-1 won't help if it just pours unburned out the back end. However, researchers working on the Turbine Based Combined Cycle engine (turbine SCRAM jet) have already been using it. I read an article of one wind tunnel test for the airforce at mach 6.

GCNRevenger · 2004-07-15 11:33:32

Methinks you are a liiiittle confused about rocket fuel Robert... today's chemical fuels do undergo chemical reaction to produce heat and the byproduct gasses, chemical fuels undergo change as well. When you burn hydrogen fuel, it all comes out as H2O out the end of the rocket.

The fuel volume itself has no bearing on the thrust or thrust efficency of a given fuel, it is simply an engineering concern. Lower density fuels need larger fuel tanks which add to vehicle weight and increases cross section, drag, and heating.

The engineering asside, the efficency of a rocket fuel is how much thrust you get for a given length of time per mass of fuel, and since Hydrogen moecules are the lightest ones in the universe, you can pack alot of them in (hence lots of energy) by mass. It is very low density and a little hard to work with, but the advantage of Hydrogen on paper is clear. Its ultra-low temperatures can even be a boon to spaceplanes, because the fuel itself could be used to cool the skin of the craft.

And air breathing engine has an advantage of lots of free reaction mass (air) even ignoring the free oxidizer yes, but alot of the advantage comes from not having to carry much or any LOX on board: the weight of a rocket grows exponentially when you start talking fuel, because you need more fuel to push that fuel, and so on. Dropping the LOX tanks decreases the weight of the vehicle many times, not by a modest margin.

the TBCC isn't a Scramjet persay, its really more like a fighter jet/ramjet combo with a LOX combustion booster that permits higher performance at higher altitudes. These would be great for getting you off the ground and to an altitude/speed to light up your Scramjet, or for a pretty large vehicle used as the first stage of a TSTO spaceplane.

RobertDyck · 2004-07-15 12:05:48

Chemical fuels go through conversion: LH2 + LOX -> H2O. You get liquid to gas phase change as well as expansion from heating. Gas expansion is dependant on number of molecules, not how big those molecules are. Therefor changing a fuel like kerosine from a single stored molecule to many smaller molecules of H2O and CO2 permits greater expansion. Gaseous heated kerosene wouldn't be a very effective propellant.

Storage size is important. The larger tank required for LH2 is very significant. In space the added tank mass is more than compensated by the increased engine performance. However, the faster an aircraft travels through air the greater the drag. Larger volume tanks mean significantly more drag. This is why engineers are currently looking at a COMBINED fuel system: kerosene for take-off/landing and flight up to mach 7, then LH2 above mach 7. Since the paper I read only demonstrated a wind tunnel test of a supersonic combustion turbine engine up to mach 6, they have one more mach number to go.

Technically you're correct, SCRAM means Supersonic Combustion RAM jet. If the engine has a turbine it isn't a RAM jet. But can a turbine engine operate at mach 10? Operation may require a shift from supersonic turbine engine to SCRAM jet to get double-digit mach numbers.

Palomar · 2004-07-15 12:33:09

Yea! Yippie! Yahoo! I seriously thought the mach 10 flight wouldn't happen, that the mach 7 flight was the last mission of X-43A. This is really good news.
Theoretically there is no cap. As long as you are flying through an oxygen atmosphere you could take it in. The problem is how much that air will heat during intake, and how much hotter can combustion make the exhaust.

*Okay, thanks Robert.

--Cindy

P.S.: If one of you brainiacs would care to go visit http://www.newmars.com/forums/viewtopic.php?t=1416]this thread and answer the question in my last post regarding tank size and gallons of propellant, I'd be eternally grateful. Sorry, but I'm wondering if there's not a typo in the article...but as we know, I really am lousy with math, so...

GCNRevenger · 2004-07-15 12:59:05

It is true you can get alot of molecules of exhaust gas per mole of kerosense, the kerosense itself is heavy with its 12x heavier carbon atoms. So not only do you have to carry the fairly heavy LOX, but the modestly heavy kerosene too instead of superlight hydrogen... Yes I know quite well that the molecular size is almost trivial.

The Saturn series of rockets were the first to employ both fuels, with the first stage run by Kerosense and the second & third stages by Hydrogen, where the upper stages would already be at altitude and have considerable velocity before the hydrogen engines would light up.

The Russians have thouht of using both propellants in one engine in their RD-701, originally intended for the MAKS spaceplane program, which did reduce the volume of tankage considerably but the engine itself is heavy and complex.

As for carrying two sets of engines, a TBCC setup running on Kerosene and a Scramjet powerd by hydrogen, this does make quite a bit of sense but it would also make the spaceplane heavier with two sets of engines, two fuel systems, and so on. Putting each set of engines, or just the TBCC and a conventional hydrogen aerospike engine, on seperate stages would seem to me to be a good plan if we wanted such a vehicle sooner than later.

the TBCC as I understand it is a turbofan of sorts... a conventional jet engine with an additional set of compressor blades on the front that pulls air around the engine and not just through it. The TBCC I think (though I may be thinking of another engine) switch to Ramjet mode at a high mach number, and simply duct the air around the turbine and burn fuel there instead of in the turbine engine.

RobertDyck · 2004-07-15 13:25:15

the TBCC as I understand it is a turbofan of sorts... a conventional jet engine with an additional set of compressor blades on the front that pulls air around the engine and not just through it. The TBCC I think (though I may be thinking of another engine) switch to Ramjet mode at a high mach number, and simply duct the air around the turbine and burn fuel there instead of in the turbine engine.

Yes, but I think the TBCC is an ejector. That is a turbojet with exhaust into the exhaust nozzle of the SCRAM jet. The draft from the turbojet exhaust pulls air through the SCRAM jet engine. It's kind of like a turbofan but without the additional set of compressor blades.

I believe this combined engine is all you need. I'm trying to imply you can close baffles to shut off the turbojet and operate the SCRAM jet alone. This should avoid the maximum speed limitation of an ejector engine.

Palomar · 2005-06-21 05:26:41

http://www.spaceflightnow.com/news/n0506/20x32a/]X-43A makes Guinness Book of World Records

*I don't see that this article has been posted previously. Did Search.

--Cindy

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#1 2004-03-25 11:37:49

Re: X-43A ramjet

#2 2004-03-25 14:29:03

Re: X-43A ramjet

#3 2004-03-25 19:18:04

Re: X-43A ramjet

#4 2004-03-26 19:23:12

Re: X-43A ramjet

#5 2004-03-26 20:48:09

Re: X-43A ramjet

#6 2004-03-27 12:49:27

Re: X-43A ramjet

#7 2004-03-27 16:49:55

Re: X-43A ramjet

#8 2004-03-27 21:12:08

Re: X-43A ramjet

#9 2004-03-27 22:07:08

Re: X-43A ramjet

#10 2004-03-28 10:05:22

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#11 2004-03-28 12:20:34

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#12 2004-03-28 13:59:50

Re: X-43A ramjet

#13 2004-03-29 10:45:31

Re: X-43A ramjet

#14 2004-03-29 22:45:01

Re: X-43A ramjet

#15 2004-03-30 08:25:13

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#16 2004-07-15 06:00:15

Re: X-43A ramjet

#17 2004-07-15 08:38:36

Re: X-43A ramjet

#18 2004-07-15 10:20:49

Re: X-43A ramjet

#19 2004-07-15 10:40:36

Re: X-43A ramjet

#20 2004-07-15 11:33:32

Re: X-43A ramjet

#21 2004-07-15 12:05:48

Re: X-43A ramjet

#22 2004-07-15 12:33:09

Re: X-43A ramjet

#23 2004-07-15 12:59:05

Re: X-43A ramjet

#24 2004-07-15 13:25:15

Re: X-43A ramjet

#25 2005-06-21 05:26:41

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