X-51A Scramjet Flight Successful
Boeing X-51A WaveRider Sets Record with Successful 4th Flight
“A Boeing X-51A WaveRider unmanned hypersonic vehicle achieved the longest air-breathing, scramjet-powered hypersonic flight in history May 1, flying for three and a half minutes on scramjet power at a top speed of Mach 5.1. The vehicle flew for a total time of more than six minutes. The flight was the fourth X-51A test flight completed for the U.S. Air Force Research Laboratory. It exceeded the previous record set by the program in 2010.”
““This test proves the technology has matured to the point that it opens the door to practical applications, such as advanced defense systems and more cost-effective access to space.“
I won’t debate this claim, but I do wish to point out that it says simply “access” to space, as opposed to human access to space. Given the small size and fuel mass of this bird (it’s a technology demonstrator), a lot more progress would be needed to even consider human use. And past (wind tunnel) programs have shown that scramjet is not necessarily a size-scaleable technology.
The fact that this is happening at the same time as SpaceShipTwo suggests to me that this launch concept is considered viable and worth investing in by people in the know, although this program, unlike SS2, doesn’t seem to be thinking in sustainable or reusable terms yet.
Considering the number of space-related capabilities that have been lost in the US, it’s nice to know that it’s still possible to do an X-15A-type bird — with significant upgrades — which is something that I very much wish had been done in the 60’s instead of spending all NASA’s money and efforts on the Moon race. Things would be very different today if X-15A had been taken further.
Congrats to all involved, and when I see promotion for a larger-scale version, which lands instead of splatting, I’ll get more excited.
Steve, You mention the moon race which brings to mind lessons taught by Mr. C. Where is he??? Is he healthy??? I do miss, a Joe Q like me, being able to sneak into his class and raise my hand and sometimes getting an answer from one so wise!
Miss him
He was permanently banned by Keith.
Yeah, it’s certainly not the same without him, but he made a silly mistake one day and suffered the consequences. We all make silly mistakes, and most of us have the brains to immediately regret them (I’m sure Mr. C saw the error of his ways), but the rules are rules, and they must apply to everyone equally. His wasn’t the first bad joke to flop on a blog, but part of what attracts me to NASA Watch is that the comments are intelligently monitored and moderated, unlike so many other blog sites which aren’t and subsequently turn into disgusting collections of infantile garbage.
What are the rules??? Is there a link to them???
Steve!
I’m very bothered by this! I feel robbed! Your rules are rules argument doesn’t cut it.
Me and Clem
I Need to think more about this!
George,
Yes, to be honest, I think you do. There are no rules published that I know of, but it’s a matter of basic social etiquette. Even though we log in to our accounts, we are still “guests” in someone else’s place, in this case a place of business.
The owner of this web site, Keith, has the responsibility for making sure it is both legal and socially acceptable, therefore he has every right to decide what is acceptable on his web site and what isn’t. You or I would be in the same position with respect to people entering our homes. If we found someone’s actions unacceptable to our standards, we’d make them leave. This is really no different.
I think it’s also a matter of simply respecting the general public. I’ve seen too many web sites, some of them for well-known publications, that are not moderated and the disgusting filth that gets posted and left there for the whole world to see makes a very bad impression and damages the web site owner significantly. There’s hundreds of us but only a very small staff at NASA Watch, yet they take the time to monitor and moderate all the comments. I see this as dedication, not restriction. They are assuring the quality of their “product” to everyone’s advantage.
The bottom line, as Keith has pointed out to others, is that if we don’t like something about NASA Watch, we’re free to go elsewhere instead. Although I, too, miss Mr. C, I have no problems with Keith’s actions with respect to people that he’s banned. Actually, he’s more tolerant than I would be in his place. I place a lot of importance on simple politeness and consideration; it’s what keeps us civilized.
Just my opinion, of course.
Steve
Steve
I WILL reply to you here when I have time to answer properly.
George
Note that it flew under scramjet power for three and a half minutes and in that time it went from Mach 4.8 to Mach 5.1. If your goal is “access to space” this is a terrible way to get there. To get into space (orbit anyway), you need to accelerate far beyond Mach 5.
No, a scramjet is far more useful as propulsion for a hypersonic cruise vehicle, not a hypersonic accelerator. Rocket engines are far better at hypersonic acceleration than this scramjet demonstrator.
I have no argument with that. But one of their goals was to get access to space with a smaller “package,” which this accomplishes for very small payloads.
It’s also probably a lot quicker to snap one of these onto a B52 pylon fitting and take off than to integrate a standard EELV launch package. This is clearly a weapons system, not intended for HSF.
I suspect that they’re after something can can either cruise or go up, and change from one to the other after launch.
The basic problem I see with this system is that scram gives you one shot and then you’re ballistic — once it drops below scram ignition speed there’s no way to:way to restart the scram mode. So, ground controllers/programmers have to guess right the first time.
I am, for some reason, unimpressed. We had SR-71s carrying humans only a little bit slower 50 years ago. 50 years later, and less than twice as fast for a much smaller technology demonstrator?
Um… The SR-71 flew at about Mach 3.5 and was practically melting down from the friction most of the time. It also had an engine not even a tenth as sophisticated You clearly don’t understand the advances in materials and engine technologies required here.
X-15 then, multiple Mach 6+ piloted flights, also decades ago. Short-sheeting the SR’s J-58 isn’t a great idea, given what it did, when, and for how many years as an operational as opposed to eternal R&D engine.
X-15 was NOT based upon an air-breathing engine propulsion system…but rather on a liquid-fueled rocket. Moreover, the complexities involved in using supersonic inlet airflow to compress the combustion chamber is far, far from trivial. So, in summary, a Scramjet-based vehicle will be an order of magnitude more advanced than a rocket-propelled X-15. Furthermore, it will have to perform much of it’s flight profile in lower altitude (denser) air…which ADDS to the complexity (shock and frictional heating, combustion stability, flight controls, etc.). A fully Scramjet-based vehicle will be as much a revolution as the first jet-engine powered aircraft.
Never said the X-15 was a scramjet. It did, however, carry many pilots to Mach 6+, and controlled landings. I understand that scramjets are hard and that they require a lot of CFD-icists doing their CFD thing. They seem to have a devil of a time performing wherever they fly. According to the release, this thing needed a B-52 and a rocket engine just to get the scramjet going.
People, since we can only speculate on the intended uses, if any, for the X-51, this may be an apples and oranges debate.
Right off the bat, X-15 was as much a science program of its time as a propulsion/airframe program, whereas X-51 seems to be solely about fast delivery to a target from a carrier plane. Although both are dropped from a bomber wing, their differences far outweigh their similarities.
Like all of the X birds, X-51 has some X-15 DNA in it, but only because X-15 was the starting point for the science of this technology.
As advanced as the “hybrid” turbojet/ramjet engine of the SR-71, it is nothing compared to the advanced computational fluid dynamics that goes into a Scramjet engine which employs a supersonic airflow through the inlet, and associative shockwave to compress air, and allow for high density, CONTINUOUS ignition of a hydrocarbon fluid for propulsion.
The SR-71 was (is) an amazing piece of technology, and nothing will take away from it’s trail-blazing performance records. But any aerodynamicist or aeronautical engineer worth their salt would be the first to exclaim the fundamental “game changing” technology that a fully air-breathing Scramjet-based vehicle represents. The advancement from Ramjet to continuous Scramjet propulsion is as great a leap as from subsonic turbojet/turbofan inlet jet engine to Ramjet hybrid…if not greater, given the incredible internal engine temperatures, combustion instabilities (that must be overcome), as well as over-all aerodynamics and long-term heat tolerance of the flight vehicle, as a whole.
Night and day, my friend…night and day
I think we can sum it up more simply: people, continuous scramjet is hard to do, much harder than in-air rocket or ramjet.
There is no margin for error with scramjet. Although the concept has been a round for a while, design and materials to actually do it are both right on the leading edge of today’s technology.
I suspect you may have come to the same conclusion that I have. This isn’t in any way about human flight, air or space. It’s a weapons development program, a successor to the cruise missile. SkyNet would be delighted.
Imagine what we might have accomplished instead for the same money.
Beat me to the punch on that. I was holding back trying not to put a negitive spin on things.
But what if someone like Musk decides to use such tech to make recoverable rockets smaller and cheaper by reducing the amount of fuel needed. Cheaper more flexable horizontal launch could be just around the corner.
Lol
What if Spacex F9R could fly down range to Mach 5 scram jet style, then turn straight up as spacex now plans for f9rs flight profile.
Yup still trying to add my jets to rockets Steve lolol
Reducing fuel and size may even make using an electric launcher worthwhiled. A large buzz bomb looking thing that jets/and rockets to space. Two stage of course
Steve the good news is they proved it works 🙂
George,
Actually we’ve known it works for a long time; it’s just the scram part that’s progress. This is a logical extension of the old X-15 program, except no longer manned.
The launch-from-a-bomber-wing method has been done many times, from X-15 through many X birds and test articles, and then Pegasus. There are advantages to it, some of which you’ve pointed out, but it will always be an unmanned situation. Mass, and therefore size, limitations constrain its uses.
The X-15A, with one man on board, could just reach the the lower limits of “space” (and was the first spacecraft to do so), so with the added velocity that scram provides, X-51A could be a cheaper LEO LV for low-mass payloads such as small satellites and, of course, weapons.
While rocket plus scram works well for the X-51, adding further technologies into the mix, as we’ve discussed before, is still a no go. For example, you can’t mix ramjet and scramjet in a single package because of the mechanical differences in their chambers, and you can’t mechanically reconfigure ram into scram on the fly.
I don’t foresee the mass/size limitation being circumvented, so it will remain a limited use system, unless they go with a larger carrier aircraft — but what’s bigger than a B-52? And the cost advantages will disappear quickly if they attempt to scale this system up.
It seems to me that the government LV options now being worked on only come in Army sizes — too big and too small.
Steve
It was never about human spaceflight-it was always a military program. Maybe 20 yrs from now it may trickle down, but right now human spaceflight is not an agenda of the military.
If NASA can make human spaceflight work on its own budget thats fine, but don’t be mistaken-everything NASA does is exploited for any kind of military application.
We’re discussing the human possibility simply because this is NASA Watch, not USAF Watch. Also, it would be nice to think that shared use might be a possibility.
Well there was the X-43 which went about Mach 10. How’s that?
It’s an Air Force wet dream: getting somewhere almost half as fast as a missile without having to leave the atmosphere. But it still needs rockets to get going. Can we stop wasting money on this concept, please?
Agreed. Although it was a staple of science fiction for years (like Heinlein’s mail rocket), it’s long been known that point to point (on Earth) travel is neither practical nor cost effective using rockets, whether ground launched or dropped from a wing.
With the dropped-from-a-wing case you lose all of the time that might be gained using a rocket in getting a B-52 to altitude. In the ground/silo launch scenario, because it’s a ballistic trajectory, you end up leaving the atmosphere just to come right back down — in other words, a whole lot of vertical to achieve a little horizontal, and short flights are worse than long flights because you have to complete at least one Earth orbit to come back down in the right neighborhood.
No matter how you slice it, this is just another weapons launch system. Do we really need another one?
Steve
In the sort term, this may lead to military applications, but I think you miss the point that this is a technology demonstrator. The project goal is to develop scramjet technology, in this case, particularly using a more practical hydrocarbon fuel. Early scramjets were designed to run on hydrogen, which adds a number of significant complications to a design.
The fact that this technology demonstrator was launched at altitude with a booster rocket was due simply to the fact that the X-51 was supposed to test a scramjet, not be a fully-developed flight vehicle. A scramjet, by definition, is designed to operate completely in supersonic flight. It cannot get you off the ground from a stand-still. An air-dropped, rocket-powered booster was the most practical, readily available way to get the vehicle past the speed of sound at altitude for its very short duration test.
On the other hand, a scramjet doesn’t _need_ a rocket. If one was developing a practical vehicle, one would likely develop a high-speed turbojet to get one up to speed. The problem with a turbojet, is that by being designed for subsonic operation, they face some fundamental aerodynamic (not to mention material) issues that prevent them from operating at hypersonic speeds. If you want to fly that fast, and do not want to haul all your oxidizer with you (as with a rocket), you do _need_ a scramjet.
As technology develops further, turbojets will reach up and scramjets will reach down to the point where they overlap to the point you can design a practical vehicle that uses both.
Without experiments like the X-51, we will never get there.
A practical vehicle to do… what, exactly? What purpose is best accomplished by Mach 6 flight through air?