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Nasa's X43a reaches mach 9.8

Posted by: André - Wed Nov 17, 2004 8:58 am
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Nasa's X43a reaches mach 9.8 
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Post Nasa's X43a reaches mach 9.8   Posted on: Wed Nov 17, 2004 8:58 am
According to NASA's website, the X43a reached a recordbreaking topspeed of mach 9.8 in a testflight yesterday. The unmanned airplane is equiped with a scramjet engine, and is considdered as a way to bring payloads into space.

I think it's really interesting that they finally have the concept working. Still, I'm curious as to how this can be an effective engine in practice. As I understand it, scamjets only work above a certain speed. That means, it will take another engine to reach that speed. A second engine means additional complexity and weight, right? Or, maybe something like this could be launced using a magnetic rail gun? Any insights?


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Post    Posted on: Wed Nov 17, 2004 10:24 am
Am I correctly informed that Scaled has been involved in the development of X43a? Or is that an error due to similarities in the names of vehicles?



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Post    Posted on: Wed Nov 17, 2004 1:56 pm
Ekkehard Augustin wrote:
Am I correctly informed that Scaled has been involved in the development of X43a? Or is that an error due to similarities in the names of vehicles?


I am not sure of that, but do not believe so, I've seen no reports to that effect.

The X43 program, according to an article I saw yesterday, is now over. NASA only built three craft---the first one crashed, the second hit 5,000 mph, the 3rd 7,000 mph. They did not even bother to retrieve this last one.

We hope, of course, that a private concern like Scaled, will pick up the technology and run with it. NASA, to put it in Austin Power terms, appears to have lost its Mojo, alas.

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Post    Posted on: Wed Nov 17, 2004 9:23 pm
University of Queensland's HyShot programme will be launching three scramjets at Woomera next year, two to Mach 8, one to Mach 10:-

http://www.uq.edu.au/news/index.phtml?article=6108


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Post    Posted on: Wed Nov 17, 2004 9:52 pm
Stellvia wrote:
University of Queensland's HyShot programme will be launching three scramjets at Woomera next year, two to Mach 8, one to Mach 10:-

http://www.uq.edu.au/news/index.phtml?article=6108


Excellent. Go Oz!

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Post    Posted on: Thu Nov 18, 2004 5:10 am
While the scram jet is undoubtedly cool tech, how practical is it?
While there is no doubt that its great to not have to carry oxidizer with you, you have to stay in the atmosphere to get it to work. This means that you have extra drag from the atmosphere, not to mention the heat sheilding required.
While I dont like to refrence the Shuttle much, it only spends about 8min in the atmosphere, with the rest of the accel done in vacume. This to me has alot of benefits, namely the reduced thermal & structural loads, an reduced power requirements.
When looking at the whole space plane idea, I often wonder whether it could ever compete against a sub orbital ballistic vehicle.


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Post    Posted on: Thu Nov 18, 2004 8:31 am
The eight minutes in atmosphere are much more than the 84 seconds burn-time of the engine of SSO in its second flight - more than five times that burn time.

So if a scramjet for manned spacecrafts could be constructed that saves more weight of propellant than it's weighing itself it would be a significant advantage.

The initial engine then is required only up to that point it has accelerated the craft to the minimum velocity required for the scramjet ignition. Perhaps this engine too can be improved.

What's left then is propellant for operations in space - deceleration for reentry, changing orbits, leaving for interplanetary space etc..



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Post    Posted on: Thu Nov 18, 2004 10:01 am
I dunno, I thought that scramjets aren't a very smart way for going sub-orbital (much less orbital). The higher you get the atmosphere is increasingly rarified and your efficiency drops accordingly. So you are going to need three engines in total ... one (a rocket) to get the speed up for your scramjet, then your scramjet and then one to take over once your scramjet is at it's last gasp. Granted, you probably don't need the third one for sub-orbital ... but it just sounds like an overly technified way of doing something.

No the only real use for scramjets is so that knee-jerk foreign policy decisions can have near immediate "impact" in distant lands.

Cruise missile at mach 10 anyone?

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Post    Posted on: Thu Nov 18, 2004 10:17 am
That seems to be depending on the desired suborbital altitude - at least some propellant could be saved for use above that regions a scramjet is working in.

Concerning the scramjet it would be interesting if it can be improved by nanotechnology - are nano- or at least micro-scramjets possible? Could nanotechnology provide smaller scramjets that are working in regions where the current scramjet cannot work?



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Post    Posted on: Thu Nov 18, 2004 11:10 am
Dr_Keith_H wrote:
I dunno, I thought that scramjets aren't a very smart way for going sub-orbital (much less orbital). The higher you get the atmosphere is increasingly rarified and your efficiency drops accordingly. So you are going to need three engines in total ... one (a rocket) to get the speed up for your scramjet, then your scramjet and then one to take over once your scramjet is at it's last gasp. Granted, you probably don't need the third one for sub-orbital ... but it just sounds like an overly technified way of doing something.

You wouldn't need three engines. You'd need two (rocket for launch, scramjet for Mach 5-15 and back to rocket again) or one (an RBCC engine of some description).

Dr_Keith_H wrote:
No the only real use for scramjets is so that knee-jerk foreign policy decisions can have near immediate "impact" in distant lands.

Cruise missile at mach 10 anyone?

I don't think Queensland is plotting to invade anywhere in the near future... but I could be wrong ¬_¬


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Post    Posted on: Thu Nov 18, 2004 1:09 pm
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... I don't think Queensland is plotting to invade anywhere in the near future... but I could be wrong ¬_¬


One should keep an eye on those blokes in New South Wales :lol: . One never knows when a preemptive strike to protect the Foster's might be called for.

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Last edited by author on Fri Nov 19, 2004 11:04 am, edited 1 time in total.



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Post    Posted on: Thu Nov 18, 2004 11:29 pm
NASA has also said that since efforts are returning to the space shuttle and the construction of the ISS (boooo!!!) that the scramjet project will be dropped.... Seems foolish to me, but what do I know, the government at least seems to think they are always correct....

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Post    Posted on: Fri Nov 19, 2004 8:29 am
Is it possible, that NASA has in mind to use the scramjet at Venus, Titan or a gas giant later? Their atmospheres are much thicker than the earthian one (except Titan at which it's only 1.4 times the earthian) - but the problem will be the oxygen. But are there two other reacting gases available at those planets that a scramjet could make use of?



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Post    Posted on: Fri Nov 19, 2004 10:04 am
Interesting thought Ekkehard - there is a book by Peter Hamilton called the Nano Flower (I think thats the one) where a (s)ramjet is used to accelerate a craft out of the Jovian atmosphere. Also, I think it was dropped from a hot gas ballon prior to launch - ring any bells??

James


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Post    Posted on: Fri Nov 19, 2004 10:22 am
I don't know that book - but I remember well that in the seventies there was a concept of a nuclear spacecraft Ulrich Walter too has described in his book. The plan was to get hydrogen out of the jovian atmosphere for a fusion drive. This has nothing to do with scramjets but has in common with it that atmospheric propellant would be used - the difference is, that the scramjet would use it at once without storing it while the other concept only would store it first instead of using it.

Sorry - no bells ring, but I feel reminded too to ARCHIMEDES, the Mars balloon of the german section of the Mars society, the Zeppeline concept for a Titan mission and two XPRIZE teams. And there is the australian team that dropped a scramjet from more than 300 km to get it ignited - they succeeded

And the australian scramjet was only 60 centimeters long - useful for private spacecrafts? What size had the X43a-scramjet?



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