X-43A Hits Mach 7

quiggy writes "As previously reported, NASA tested the X-43A yesterday. The results are in, and the scramjet hit Mach 7, setting a new speed record. CNN is also reporting the story, with a note that a similar jet could be tested by the end of the year, hopefully reaching Mach 10."

Stupid, Slightly OT Question

[dupper]

The news media keeps reporting NASA's previous failure to reach Mach 5. But didn't the X-15 do this in, like, the 60's?

And, to keep a little more on topic:
18 tiems the speed of light!

Mach 10

[Boss, Pointy Haired]

is 3402 meters per second

or 12247 kilometers per hour

or 7610 miles per hour

Speed of sound

[CaptBubba]

For those of you wondering how to convert between Mach numbers and mph or m/s, here's a nifty java tool [nasa.gov] that lets you see how altitude affects the Mach number.

basically the higher you go, the less air there is, and the slower sound travels. So, the mach number, which is the ratio of your speed to the speed of sound, will be higher at high altitudes if the speed is constant.

Re:Stupid, Slightly OT Question

[stripmarkup]

Yes, they did it in the 60s [af.mil]. They reached Mach 7 with a manned plane. This one is unmanned. I don't understand why it is such a big deal.

CNN gets it wrong

[AlecC]

It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours.

Considering Concorde did that in three hours, thit wouldn't be much achievement. I make it that it could do NY-LON in just over one hour.

What I think they should have said is that it could go from any point on the earth to any other, including the antipodes, in less than five hours.

Mind you, it would take three hours to get through security on departure and an hour on arrival to collect your baggage, if it had arrived with you.

Re:Stupid, Slightly OT Question

[Boccaccio]

That was a rocket - this is an air breathing engine.

The Mach 10 is not enouth...

[S3D]

Mach 10, projected speed to the end of the year is about 1/3 of the orbital velocity. While already in the same order of magnitude it is still a long way toward the space plane...

Great Things to Come

[Denix]

I think this finally points to a replacement for the space shuttle that was sorely needed. The shuttle is a decent space truck, but we need a cheaper (and safer) space "bus."

Hopefully it will be designed with a space station or dock in mind. It's my understanding that the shuttle was retrofitted for in-space docking such that the International Space Station almost had to be built around it.

"And how much more black could it be? None more black." - Spinal Tap

Why its important

[Veteran]

SCRAM stands for Supersonic Combustion Ram (jet). What makes this different is that the combustion is taking place in air which is moving faster than the speed of sound inside the engine. Conventional Ram jets require that the air inside the engine be moving at less than sonic velocities for combustion to occur.

Conventional Ram jets are limited in top speed by the necessity to slow the incoming air down to sub sonic velocities.

Not only does the SCRAM jet have potential military applications, it can also serve as a 'midrange' stage for a lower cost to orbit booster.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

x-15 == rocket powered
this time == jet powered

That is why this is different

X 15

[p51d007]

Yeah, Pete Knight went to Mach 6.7 in Oct 67....STILL a record to this day, for a MANNED airplane (X-15 isn't "really" a traditional airplane since it is air launched). Also Pete Knight earned astronaut wings by flying the X15 near 300,000 feet. Several of the X15 pilots received astronaut wings by flying near or over 300,000 feet. Joe Walker, went the highest to 320,000 feet! Sadly, he was killed in the 60's when he was in a formation of planes for an Ad for the general electric engines that all the planes were flying. His "tiny" in comparison jet got too close to the XB-70 bomber (which was suppose to be a Mach 3+ bomber) and it went inverted and smashed into the tail of the bomber, and exploded. Sorry, the early years of test pilots, NASA has always fasinated me, and buddies of mine call me a walking encyclopedia of aircraft knowledge ;)

SCRamjet = Supersonic Combustion Ramjet

[amigoro]

So what's a Ramjet?

There's one fundamental difference between an ordinary jet engine and a scram jet engine: The Ramjet has no moving parts.

The all jet engines,operate according to Newton's Third Law of Motion:
For every action, there's an equal opposite reaction

The standard jet engine, invented by Sir Frank Whittle, sucks in air at the front. Then this air is mixed with fuel, and made to combust. The combustion causes the air to exit the engine at a velocity greater than when it came in, thus creating thrust. The escaping air causes the turbine to spin, and this intern activates the compressor, sucking more air in.

The Ramjet has no turbine and compressor unit. Ramjets fly supersonically and have an inlet which injests subsonic air after it goes through a shock wave in front of the inlet. The intake is slowed down aerodynamically, and then mixed with fuel and made to combust. But after about Mach 5, ramjets don't work so well.

The scramjet is almost but not quite entirely like a ramjet. The only difference being in a scramjet the combustion takes place as the air is travelling through the chamber at supersonic velocities.

More [uq.edu.au] about the scram jet. Or another [aviation-history.com] more concise explanation.

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Re:Speed of sound

[mindstrm]

Common misconception.

The speed of sound in a gas is affected mainly by temperature... not density or pressure.

From the page you just linked to:
"The speed of sound depends on the state of the gas; more specifically, the square root of the temperature of the gas."

Mach at 35,000 ft is 663mph

Mach at 150,000 ft is 732mph

The reason higher aircraft hit higher mach numbers is due to decreased air resistance... concorde can hit mach at 50,000 ft, but not at 20,000.. not because mach is perceptibly slower, but because there is less drag.

CNN should take a look at the history books...

[Anonymous Coward]

Taken from the CNN article:

"It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours."

Wow... Concorde used to cover the distance in about 3.5 hours...With turbojets. Now that's progress!

A flight at mach7 between NYC and London should take less than an hour... with most of the time spent circling over the destination in the holding pattern before landing...

Re:Stupid, Slightly OT Question

[mindstrm]

It's not. This whole experiment is not at all about speed, and everything about a new engine design.

IIRC, Mach5 is the speed at which the scramjet is released, and ignited... up until then it's just being boosted by a conventional rocket.
During the first test, the scramjet failed.

During this test, it worked, pushing the rocket up another mach or two.

This was not meant to be any kind of speed record.. that's just how fast you need to go to get a scramjet working.

But it isn't nothing.

[Anonymous Coward]

Instead of a rocket launching this vehical, it's big brother could launch a rocket then return to earth for reuse. Bigger satellites, smaller cheaper, simpler rockets, both.

And BOOYA think of the cruise missles. KE=vmv/2.

Shit hits the fan, but the battle group isn't on station? No worries. Diplomacy is en route. Maybe paint a little picture of gerry-curl sam jackson smoking a cigar on the front of each one.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

The big deal is the difference between Mach 6.72 and 7. And the speed was achieved with air-breathe engine (c.f., any rocket would exceed Mach 7 all the time, but then their engine does not intake compressed air to gain thrust).

I've been dreaming about a working scramjet since 80's. Well done guys at Dryden.

-b

Adtional information on scramjets

[Faith_Healer]

If you want some something that will help understand the scram jet and you have a little aerospace knowledge check out this paper on combustion on a supersonic stream, http://www.anu.edu.au/Physics/aldir/publications/H yslop_hons_thesis_1998.pdf. Its amazeing that this jet can sustain a burn with out a flame holder, at least it looks like it does.

Re:Mach10?!

[It's the tripnaut!]

And just how do you keep something going that fast from burning up in the atmosphere?


...by travelling in the exosphere [mmu.ac.uk].

Re:sublight speed ;)

[fredrikj]

Indeed. You need to account for friction, though. Wikipedia article on escape velocity [wikipedia.org].

Re:sublight speed ;)

[Kiryat Malachi]

Uhm.... no. You are correct in your definition of escape velocity, but orbiting spacecraft reach speeds just about as fast.

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface. Thus, when Shuttle is orbiting at 300km altitude, it is traveling at 7.73 km/sec. In order to achieve that orbit, it has to achieve that speed, tangential to the direction of gravity. It can do this (neglecting friction) in one burst at ground level, or over time, but it has to hit that speed to hit orbit.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

No, during the first test the rocket booster (the Pegasus) failed, mostly due to being released too low in the thick atmosphere. The entire package was destroyed by mission control before it went totally out of control.

Re:Stupid, Slightly OT Question

[the eric conspiracy]

I don't understand why it is such a big deal.

As some have noted, it's because of the engine type - air-breathing - that makes this so significant.

The economics of space travel are dominated by the cost to put something in orbit. Sitting on the launch pad, the payload to weight ratio of the Shuttle system is something like 1:50. Picking up the oxygen just lying around gives you a big increment in payload to weight ratio.

Re:Mach10?!

[costas]

Mach 10 is a record for powered flight; it is not even close to the record of a man-maned craft; IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

The real problem here is that a scramjet engine is very sensitive to its input (the air coming in) as it only spends literally milliseconds in the combustion chamber. So you have to wonder what aerodynamic tricks the X-43A designers are pulling to smooth that flow before it goes into the intake. Notice the side-view of the aircraft; the belly is smooth and curvy in order to produce many small shocks ahead of the intake and slow down the air as much as possible. A terrific aerodynamic feat, I just have to wonder if it will be reproducible (i.e. stable enought and robust to any aerodynamic event) for a manned aircraft. [Yes, I am an aerodynamicist].

Re:Feasibiliy of High Speed Travel

[mindstrm]

Not that massive.

Shall we calculate?

Let's say for rough estimation purposes mach is about 1000km/h, or 277.8 m/s
So mach 7 is 1944m/s

Let's say that G is 9.8m/s^2 (It is)

1944/9.8= 198.4 seconds

In other words, at 1G, after 3 minutes and a bit ,you will already be cruising at mach 7.

IN that time, you would have gone approximately 193km.

Factor in the same for deceleration... and we could say.

You could comfortably go 400km in about six minutes. Less than that and this speed is not practical.
For that matter, you spend more time in preparation and airports than you do on an aircraft for a 400km flight in the first place... so mach 7 would be really practical for longer flights.

Re:Speed of sound

[Inspector Lopez]

To first order, the speed of sound does not depend upon the pressure at all; rather it depends primarily upon the mean mass density and the temperature.

The reduction of sound speed at altitude is due to the reduction of temperature. The temperature rises again in the upper stratosphere (ozone heating) and then drops down to its coldest temperature at the mesopause (around 120 K, at 85 km). However, the temperature increases rapidly above that, getting back to room temperature by 110 km, and heading for 1000k and beyond by the time you get to LEO.

At high altitudes the mass density is decreasing as you get more and more atomic species (e.g. O rather than O2) as well as larger fractions of light constituents (e.g. H2, H), so the speed of sound is quite high at LEO. At altitudes above the "turbopause" (somewhere around 105 km) the components of the atmosphere are no longer well-mixed, thus the different component gases stand at their own scale heights.

see scale height [wolfram.com] and speed of sound [wolfram.com]

Re:sublight speed ;)

[SillyNickName4me]

It is a speed record for a vehicle driven by an air breathing engine (ie, it gets its oxygen from the atmosphere)

Rockets have gone faster, but they carry their own oxygen.

Re:Mach 10

[Anonymous Coward]

Not at 95000 feet (the altitude the article claims). Assuming a standard atmosphere [stanford.edu], the speed of sound is 315 m/s. So Mach 10 is 3150 m/s.

Re:sublight speed ;)

[AndroidCat]

Rockets still have to reach escape velocity, regardless of how long they boost. However you're right about ground level--the further away, the lower the escape velocity required.

If I jumped in a '57 Space Coupe (2457) and gunned it for the stars at a constant 120 MPH, after a very long time, I'd be far enough away that escape velocity would have come down to 120 MPH and it would be safe to switch off the ignition.

Re:sublight speed ;)

[Maimun]

So an escape velocity can vary in speed as the angle of escape changes.

Wrong! It absolutely does not matter which direction the velocity vector points to. All that matters is the kinetik energy of the body. The kinetic energy is 1/2 * m * (v^2), where v is scalar, the speed in your terminology.

See this page [gsu.edu], it is really neat, you can compute escape velocities for different planets.

Armchair physicists are idiots

[Anonymous Coward]

Let's sum it all up. 1) Escape velocity is IRRELEVANT in the discussion. That applies to unpowered vehicles - not a vehicle under constant power such as this one.

2) As has been already posted. The speed record isn't for ANY vehicle. The record is for a vehicle with an air breathing engine (ramjet, scramjet, etc). It doesn't apply to vehicles such as the X-15, Apollo capsules, the space shuttles, etc as their speeds were/are either rocket powered or unpowered reentry.

3) During the first test the scramjet engine did NOT fail. It was never even fired. The booster engine that was supposed to get the scramjet to mach 5 is what failed. If I remember right the fins or something fell off and it went out of control so the remote detonated the booster and consequently the scramjet testbed attached to it.

4) The toyota corolla attachment won't be out until 2006.

Re:sublight speed ;)

[slim-t]

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

I don't have a physics book handy, but I'm pretty sure mass has nothing to do with the velocity.

Re:sublight speed ;)

[Andy_R]

Actually, you don't need escape velocity to escape the earth. Any velocity will do if you carry on for long enough. Escape velocity is a measure of how fast you need to be moving to leave *if no additional thrust is applied*, which, given the fact that you are probably strapped to a huge big rocket if these things are relevant to you, is rarely the case.

Uhh guys...this has been done before

[shthd]

From cnn It is the first time a supersonic-combustion ramjet, or scramjet, which uses air for fuel, had traveled so fast, flight engineer Lawrence Huebner told reporters. The University of Queensland Launched the HYSHOT in July 2002. It Hit Mach 7.6. The first people who did this [space.com]

This thing is (*TINY*)

[blair1q]

Take a look at the photo of the actual X-43 [yimg.com].

All the pics were of the Pegasus booster rocket which was dropped from a B-52. You can't even resolve the X-43 in those photos.

That X-43 is smaller than most of the bombs that B-52 has dropped in its lifetime.

Re:At the present rate

[NeoThermic]

In 1994, a paper was written by Miguel Alcubierre which detailed a possible way of obtaining warp drive.

The current problem is that of relitivty, at which there is a certian point where energy stops creating speed, and goes into increasing the mass of the moving object, thus making light speed impossible.
Alcubierre's idea was that the ship doesn't move. Instead, it modifies the space around it much like an esclator. Since the ship doesn't move in relitive terms, it doesn't gain mass or suffer time dialation.

However, at this time, there was a problem with obtaining the required energy, which was quite alot [think total solar output of the sun in its current life, per second].
In 1999, however, Thomas Valone spotted an answer. Zero Point Energy. In a nutshell, one can theoretically harness the binding energy of a particle. This energy, if harnessed, would be enough energy to power an Alcubierre warp drive.

However, both ideas are still in the working stage, and I think we will see Duke Nukem Forever before we see warp drive from either of these two concepts.

NeoThermic

Re:CNN Errors and the quarter mile

[ralphh]

One G is about 22 mph/s, so 1400 mph/10s is a about 6.4 G's.

the scramjet did not accelerate to mach 7

[lfnoise]

According to their press conference yesterday, the maximum speed was attained at booster burn out. The scramjet achieved positive thrust, but it was decelerating the whole time (10 seconds). The speed was therefore the result of the booster and not the scramjet.

Re:sublight speed ;)

[wass]

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

Not exactly true. When solving the two-body system, a number of coordinate transformations change the equations of motion into a simple one-body equation that can be solved exactly. The mass in the transformed one-body system is called the reduced mass, which is defined as mu=(A*B)/(A+B), where A and B are the masses of the two bodies in question.

Assuming A>>B (ie, Earth is much greater than the mass of a satellite), this can be rewritten exactly as mu=B/(1+B/A), or w/ a first-order taylor expansion as mu=B-B^2/A. For a standard communications satellite, the second term is approximately 10^-18 times smaller, and can realistically be dropped, and the mass of the satellite is to within measurable uncertainties B.

But you're wrong in general when you say it's independent of the mass of the object it's orbiting. In the system of the moon orbitting Earth, there's about 1% error by replacing the reduced mass by moon's mass. For a more dramatic example look at a binary star system where one star has 3x the mass of another.

Re:CNN Errors and the quarter mile

[lfnoise]

It was taken to mach 5 by the Pegasus, then it accelerated under the scramjet to mach 7

This is not true. The pegasus booster took it all the way to mach 7. The scramjet proved it could make positive thrust, but it did not accelerate, it actually decelerated during those 10 seconds. Maximum speed was at booster burn out. This is according to their press conference yesterday.

Also, see this video: (remove the space in the URL)

http://www-pao.ksc.nasa.gov/kscpao/videos/metafi les/ksc_032504_x-43.ram

Perfomance and economy

[soldeed]

Orbital velocity is damn near escape velocity, and thats the whole point. Getting to orbit economically is the key to making space travel pay instead of cost. It takes WAY more energy to get to orbit than to get from orbit to anywhere else in the solar system. Think about the Saturn V moon stack. You needed all the fuel in the 1st and 2nd stages, and most of the fuel in the 3rd, just to make orbit. only a small additional thrust from the third stage was required to send it on its way. We have all sorts of economical solutions for interplanetary travel, such as ion engines, solar sails, and nuclear engines. We need an economical booster technology, and this is it! 3500 mph to 5000+ mph in ten seconds with TWO POUNDS of fuel! Thats outstanding power and fuel economy In my opinion.

Re:10 seconds

[lommer]

In the scramjet reasearch buisiness, 10 seconds is an eternity. Most institutions who are researching this technology are universities and the like who don't have access to B-52s, rocket boosters, and the other equipment needed to actually flight test scramjets. Rather, they are forced to rely on less expensive wind tunnels. To simulate >mach 6 airflow (scramjet operational range), they either use an enourmous piston driven system, or a series of pressure build ups with a simultaneaous release. Regardless of the method, these techniques generally can't provide more than 5 milliseconds of flow time to test the engine. If you compare testing engines in 5 ms bursts to one sustained 10 s flight, the perspective kind of changes your opinion on how long 10 s is.

If you want a good paper on the subject, I suggest this one [anu.edu.au] from the Australian National University.

Re:Uhh guys...this has been done before

[Anonymous Coward]

Not quite, according to the NASA link the scramjet ran for about 10 seconds out of the 6 minute flight.

Re:Perfomance and economy

[corngrower]

Mod parent up. This is correct. Orbital velocity is the velocity an object needs to maintain an orbit about a planet (or another object). This is a tangential velocity. Escape velocity is the velocity necessary for escaping the gravitational pull of the planet (or other object).
Escape velocity is faster than orbital velocity. But like the parent poster says only a relatively small amount of thrust is needed to gain escape velocity.

Most of the energy in the fuel in a rocket is used to accelerate the remaining fuel in the rocket. Not having to carry along the oxidizer for the lower portion of the flight would save a lot of weight.
And with less oxidizer you need less fuel as well.

12-feet-long. Small in proportion

[johnjay]

I think the X-43 is 12-feet-long. This quote:

"The unpiloted 12-foot-long vehicle, part aircraft and part spacecraft, will be dropped from a B-52,aircraft. It will be boosted to nearly 100,000 feet by a rocket..."

from this [nasa.gov] NASA page is one source.

I think you are underestimating the size of the Pegasus rocket and B-52 bomber. I know I did. A quick google search found a page on the Pegasus rocket: it is 55.4 feet long and about 4 feet in diameter.

Re:the scramjet did not accelerate to mach 7

[KD5YPT]

You're right, scramjet didn't accerlerate to mach 7, the only thing they're testing is that CAN scramjet operate when the air flowing through it is at mach 7. Because in the past, the major problem with scramjet is that when it approaches mach 6, the speed of the airflow literally snuff out the engine. Now they seems to be able to keep the scram jey burning at mach 7 (now they just need that thrust).

Re:Uhh guys...this has been done before

[Chairboy]

Nope, the X-43 flew under its own power for 10 seconds.

Re:Doubt it Re:10 seconds

[WolfWithoutAClause]

Um. No. Density of LH is a tiny fraction of gasoline- just 70kg/m^3.

Compare this to liquid oxygen which is (IRC) more like 1100 kg/m^3; or water 1000kg/m^3. Gasoline or kerosene is slightly lighter than water, but not a lot. Liquid Hydrogen is seriously not dense- that's actually the biggest problem with it.

Re:Uhh guys...this has been done before

[Anonymous Coward]

The Australian scramjet produced no net power (as it says on the website), so any acceleration was caused by gravity. NASAs produced net power (accelerating from Mach 5 to Mach 7 if I remember correctly).

Re:Uhh guys...this has been done before

[shthd]

Nope, X-43 did not accelerate from Mach 5 to Mach 7. The booster carried it all the way up to that speed. The x-43 got ignition going at mach 7 which is an incredible feat. When you read into the article that it accelerated from mach 5 to 7 it was the fault of crappy reporting.

Re:sublight speed ;)

[Anonymous Coward]

Available here [ucl.ac.uk] It's Windows only. Requirements are:

• 300 MHz PC or better (Pentium, Athlon, etc.)
• 128MB RAM or more
• Windows 95/98/ME/2000/XP
• DirectX 7.0 or higher
• DirectX compatible 3D graphics accelerator card with at least 16MB of video RAM (32MB or more recommended) and DXT texture compression support.
• Approximately 60MB of free disk space for the minimum installation (additional high-resolution textures and addons will require more space).
• DirectX compatible joystick (optional)

Re:sublight speed ;)

[wass]

You must have missed the entire point of my post. I was showing how mu exactly is B/(1+B/A). This will always be true for the 2-body system. There is only one assumption I made, which was for the satellite that A>>B. This assumption doesn't do anything until it's realized with a 1st-order Taylor expansion.

The whole point of the Taylor expansion was to give an estimate of the difference between B and mu, and in this case it's -B^2/A (to 1st order). If you don't like the expansion then keep the exact form, or take the taylor expansion to higher orders.

Anyway, since you missed the mathematics of my post, here's a recap of simple Taylor expansions.

Binomial expansion : for 1>>|x| (and n not insanely large), (1+x)^n ~= 1+(x*n)

So 1/(1+x) ~= 1-x

Recall mu=B/(1+B/A) exactly. To within some specified precision, mu~=B-(B^2/A). You can compare exact to approximate answers to see what the error terms will be.