back to article Scramjet X-51 finally goes to HYPER SPEED above Pacific

The US military may have finally achieved its goal of powering a sustained hypersonic flight on relatively ordinary jet fuel, according to a report. The first X-51A and its booster rocket mounted ready for release from B-52 mothership. Credit: USAF Fourth time lucky, maybe? Aviation Week says that the fourth and final X-51A …

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Flame

Well done-

Next- Thunderbird 1.

Hypersonic Fire

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Facepalm

Why more Weimar?

"The palmy days of War On Stuff budget bulge are over for the US military"

I didn't hear about Eisenhower being back in the presidential seat. I think the debtmonetization express is going to roll to ultimate wreckage whatever happens.

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Re: Why more Weimar?

" I think the debtmonetization express is going to roll to ultimate wreckage whatever happens."

Well, you never heard such squealing as when the sequestration cuts came into effect. Of course that's only about a 7% cut, so nothing like the 50% cut that's needed if Uncle Sam wants to balance the books. I'm with you that they won't sort the deficit out, with the US going the way of Europe (lots of lovely but unaffordable entitlement schemes), but the US military will still have to make their own guns or butter choices.

And offer a five star general a choice of troops,or aircraft, or bombs, or some applied research that might one day make a weapon, what's he going to choose? Nope, not research. Which means that all those exciting rail guns, death star lasers, and scramjets simply aren't tangible enough, and are at risk. With scramjets it's a pity, because there might be civil applications many decades hence.

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Facepalm

Firstly, congratulations... secondly... so, what is the benefit now???

It's a scramjet that has to be launched like a missile with a massive rocket to get it up to speed first?

It's only real use is on a cruise missile, there is no real other benefit, i.e. no use on a fighter jet, pointless to consider on a commercial liner, and it would not even make space launches cheaper!

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Yes, because all technology is first tested in a final state, ready to be used for a random joe public's pet project.

Heck, even trains were initially dismissed as useless, as were cars and computers...

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Meh

@John Robson,

Bah, Computers! I wouldn't go near one!!

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Boffin

Remember Lasers?

When they were first invented they were referred to as "A solution in search of a problem".

How did that work out?!

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Quite well for evil geniuses and their sharks.

This may seem like good old fashioned American military madness, but it has potential to filter into civil avionics via new engine designs. True it seems like every couple of years boeing or whoever releases a render of a supersonic plane that can go from London to Sydney in 12 minutes, mad shit like this is what gets us closer to that one day being a reality. Look at the origins of the jet engine. Look at the origins of radar, or rockets which we use for satellites (telecoms \ weather). 'mad war research' shouldn't be given free reign, but neither should it be written off as useless.

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The Scram jet has been envisioned as orginally part of the Space plane/bomber (http://www.aviationweek.com/Article.aspx?id=/article-xml/awx_05_02_2013_p0-575769.xml ). The idea is to deliver a bomb or missile at great distances in 30 minutes or less and then return to back. The space plane could also drift aloft in in space and be ready to deter countries like N Korea or China. The scram jet is still in R&D phase and will take some time before the technology is perfected. There are other uses such as space laser platform. A hypersonic missile is possibility, but I doubt it will be used in a ICBM.

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Coat

Or a pizza...?

else it's free.

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I am not dismissing it as useless, but asking what use it it beyond a cruise missile?

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Go

it would not even make space launches cheaper!

The idea is to launch it by mass driver so you won't need the rocket stage. The SCRAM takes the craft to escape velocity and then you'd just need a little rocket-nudge to get orbital insertion. This means that you can ditch the oxidizer - a big part of any lift budget, weightwise.

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Mushroom

@MrXavier

Nobody was claiming it was the finished product, it's just research. Sure it can't immediately be strapped to a commercial airliner and make it fly London to NYC in <1hr, but the data gathered goes into the next gen of research and eventually we have (hopefully) hypersonic airliners that can transition from turbojet to scramjet flight without booster rockets.

Re:ICBM launch, surely launching a hypersonic cruise missile is a damn site less conspicuous than launching an ICBM. So much less conspicuous that you could conceivably deny it all together, if anyone except the target noticed it in the first place.

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Re: @MrXavier

Oh I would love to hope they could, but unfortunately due to the way scramjets actually work, I can't see how they could ever have a dual mode engine, scram & turbojet...

Although possibly a pulse jet - scramjet hybrid could be built if they could get the fuel efficiency high enough

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On course for UK - Oz in 30 minutes

and a 6 hour wait at the airport

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Re: On course for UK - Oz in 30 minutes

Just out of curiosity, wouldn't the G-forces involved with hypersonic stuff end up laminating the pilot/passengers to the rear wall of the plane?

Not a troll, just a genuine question. =)

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Anonymous Coward

Re: On course for UK - Oz in 30 minutes

Going fast doesn't say anything about acceleration. You could accelerate from zero to 7200 km/h (roughly Mach 6) in 3 minutes at 1 G (1.4 G experienced by the passengers, since you'd have 1 G downward due to gravity and 1 G horizontally due to acceleration, take the vector sum at 90 degrees and you get 1.4G).

It would take longer than 3 minutes to climb to the altitude you'd need to be at to safely travel Mach 6.

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Headmaster

Re: On course for UK - Oz in 30 minutes

A quick look at the Apollo 11 launch profile shows it hit 2 km/s (~Mach 6) at about 2 minutes post-launch. So no pancake.

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Anonymous Coward

Re: On course for UK - Oz in 30 minutes

> Just out of curiosity, wouldn't the G-forces involved with hypersonic stuff end up laminating the pilot/passengers to the rear wall of the plane?

Shouldn't do; it might be uncomfortable* but not fatal. For comparison the shuttle crews generally pulled about 3g and the legendary John Paul Stapp took a sustained 25g with a peak of 46g** after ride on a rocket sled.

* +4g is fucking weird if you have no experience of high G.

** It's worth noting that he did this, voluntarily, in a time when 8g was thought to be fatal. Like I said, legendary.

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Megaphone

Re: On course for UK - Oz in 30 minutes

>John Paul Stapp took a sustained 25g with a peak of 46g** after ride on a rocket sled.

Yep and there have been cases of F1 drivers in wrecks momentarily being exposed to nearly 200g and surviving (ie 300 kph to virtually 0 in a meter).

>** It's worth noting that he did this, voluntarily, in a time when 8g was thought to be fatal. Like I said, legendary.

Yes the man not only saved a whole lot of pilots but he figured out the thing killing his pilots (tasked as doctor with safety of pilots in military) the most was actually car accidents and he was the one that pushed for seat belts in cars that save countless people every day.

>You could accelerate from zero to 7200 km/h (roughly Mach 6) in 3 minutes at 1 G

Yep and when we have the technology you could go from 0 to just under light speed (damn relativity) accelerating at 1G in a shade less than a year .

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Unhappy

Re: On course for UK - Oz in 30 minutes

"Shouldn't do; it might be uncomfortable* but not fatal. For comparison the shuttle crews generally pulled about 3g and the legendary John Paul Stapp took a sustained 25g with a peak of 46g** after ride on a rocket sled."

IIRC his last ever ride was to -60g as some documentary mentioned it was the same force that Princess Diana experienced when her limo hit the pillar in the tunnel in France.

Survivable in a 4 point safety harness if you're prepared to be treated for a detached retina afterward.

That is something you want to avoid.

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Re: On course for UK - Oz in 30 minutes

Force is only applied with acceleration or deceleration. Speed it self is not making up any force.

A space shuttle accelerates with a force of around 3g. Some extreme fighter pilots needs to be able to maintain cautiousness for a short period in up to 12g. This is achieved with very aggressive turns, where you get the so called "centrifugal force".

In conclusion only when your speed is changing in any direction you deal with forces, with one exception, gravity.

It's because of this force you can stand on a scale and measure your weight. Force is measured in Newton Meters (Nm) or with a gravity constant g. 1 g is around 9.81 Nm. But the exact value of the gravitational force varies from location to location. So when doing exact calculations Nm is used.

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Boffin

Re: On course for UK - Oz in 30 minutes

Force is measured in Newtons (N). Mewton-meters is momentum.

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Joke

Re: On course for UK - Oz in 30 minutes

"Force is measured in Newtons (N). Mewton-meters is meowmentum."

FTFY.

(I know, I hate it when I let a speling [sic] error like that through as well.)

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Coat

Re: On course for UK - Oz in 30 minutes

Mewton-meters is the force with which a cat compels you over a distance to open the door for it, or feed it.

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Re: On course for UK - Oz in 30 minutes

+4g is fucking weird if you have no experience of high G.

According to Wikipedia, one common carnival ride exposes riders to 3.5g. I dubious many people would be able to distinguish between brief experiences of 3.5g and 4g, and I've never heard a carnival ride described as "fucking weird". But no doubt YMMV.

That said, a couple of online references I found with a quick search suggest acceleration for commercial aircraft is rarely higher than about 1.5g (accidents aside). I expect 3g, even for short periods, would be disconcerting for many passengers and dangerous for some in relatively poor health or otherwise less able to tolerate it. For your average business traveler, probably not an issue, but liability would be a concern if this were commercial technology.

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Re: On course for UK - Oz in 30 minutes

>Force is measured in Newtons (N). Mewton-meters is momentum.

er.. Nm=torque (or moment .. so close, I guess)

momentum is kg m/s (i.e. mass * velocity)

</pedant>

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Meh

"It was hoped that the X-51A would break Mach 6"

Er, last time I looked Mach 6 was included in the set of "speeds in excess of Mach 5", so it doesn't actually say that it didn't go that fast.

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Pint

Re: "It was hoped that the X-51A would break Mach 6"

True, it could have got past MACH6. But if it had, they would advertize it as "greater than MACH6". By the same logic, it could have got faster than MACH 10 (it IS faster than MACH5). But they would say it, don't You think?

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Thumb Up

Re: "It was hoped that the X-51A would break Mach 6"

I would assume that all Av Week knew was that it went hypersonic and translated that into "speeds in excess of Mach 5" for excitement. I'm in agreement that it could well have done Mach 6.

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Mushroom

An ICBM launching a conventional HE warhead would be even more riculously expensive and wasteful than a scramjet hypersonic missile would be.

Nukes also don't need to be particularly precise, for obvious reasons, so to producing a ballistic warhead capable of fulfilling this mission wouldn't just just be a case of taking the nuke out and stuffing it full of explosives - it would need to have a terminal guidance solution to allow to be at least as accurate as current precision munitions.

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>it would need to have a terminal guidance solution to allow to be at least as accurate as current precision munitions.

Guarantee this could be done quite easily. <1 meter precision without breaking a sweat.

>An ICBM launching a conventional HE warhead would be even more riculously expensive and wasteful than a scramjet hypersonic missile would be.

1 trillion USD in Iraq, 1 trillion USD in Afghanistan (direct costs only that can't be argued, indirect costs for whole war on terror fiasco may end up being more like 6 trillion) , the US government wrote the book on ridiculously expensive and wasteful.

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>Guarantee this could be done quite easily. <1 meter precision without breaking a sweat.

Not easily at all. <1 meter precision requires a terminal guidance precision that is quite difficult when the reentry vehicle of an IBCM is moving around 25,000 kph and sheathed in plasma. For Prompt Global Strike, Tridents with GPS terminal guidance were proposed that were expected to obtain an accuracy of about 10 m (down from the 100 m or so of the nuclear variety that cannot rely on GPS, for obvious reasons). Incidentally, the comment you were responding to was incorrect in the assessment that the missiles would need to be "at least as accurate as current precision munitions"- a projectile can afford to be slightly less accurate when it has an impact speed of Mach 17.

*Shorter-range quasi-ballistic missiles, moving at something more like 8000 kph, should be easier to maneuver in atmosphere, but there are theatre-class weapons only, so aren't much use for a "global strike".

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Unhappy

"1 trillion USD in Iraq, "

But according to one report there are around $13 terra dollars missing from the people of Iraq, so the US is very much ahead on profits.

Of course if I were an Iraqi and knew that I'd be pretty p**sed off too.

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FAIL

what?

All of Iraq's oil reserves altogether probably wouldn't add up to 13 trillion. The whole middle east minus Israel GDP is less than Spain's (pre recession). I won't deny the human costs and probably some Iraq money was stolen to help with the no bid contracts but no way it more more than a tiny fraction than the US taxpayer got bilked out of.

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Joke

Reminds me of Spaceballs

What's next, Ludicrous Speed???

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Pint

Re: Reminds me of Spaceballs

Hadn't you better buckle up?

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Coat

Re: Reminds me of Spaceballs

WHAT? You went over my helmet?

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Mushroom

Since a lot of people are pointing out how this wouldn't work in practice. How about...

A missile rack embedded in a satellite with re-entry shields on the missiles. Need a boom? drop one from orbit then once speed passes mach 3 or 4 from the force of gravity ignite the scramjet.

Just a thought.

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Anonymous Coward

space weapons are banned by treaty.

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Anonymous Coward

@Sulehir

Not even remotely necessary - a de-orbiting completely inert metal telegraph pole would impact at about Mach 10 with no help at all from a booster, scramjet or otherwise. cf. the 'Rods from God' concept.

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Re: @Sulehir

True, I was thinking of the scramjet more for a high speed change of trajectory, for targets that you want to hit at just a bit of an angle and fine grain aiming.

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Boffin

Re: @Sulehir

"a de-orbiting completely inert metal telegraph pole would impact at about Mach 10 with no help at all"

You'd probably find it wouldn't get anywhere *near* the surface.

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Re: @Sulehir (@ Annihilator)

"You'd probably find it wouldn't get anywhere *near* the surface."

Both devices would need a rocket for de-orbiting, of course, but from that point on, the 'rod' is just an inert lump of metal, far less expensive -and lest prone to failure- than the scramjet.

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Re: @Sulehir (@ Annihilator)

And "inert lump of metal" falling uncontrolled at high speed into our atmosphere would most probably burn up long before it got to the ground, was my point.

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@ Annihilator

Nope. You're wrong. Satellite parts routinely survive reentry, and they're flimsy compared to a solid tungsten telegraph pole.

This technique isn't merely a thought experiment - they would impact with the severity of a tactical nuclear missile, with accuracy measured in feet with existing technology, and have been considered for deployment by the US military - The only reason they haven't been is that it's too.expensive to get that amount of mass into space.

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Boffin

Re: @Sulehir

"You'd probably find it wouldn't get anywhere *near* the surface."

Depends what you make it out of.

Tungsten has a melting point of 3000c+ and a specific gravity around 19. A big enough lump of that will survive to ground level and make quite a hole in whatever it hits.

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Childcatcher

a solid telegraph pole

...is a lot of tungsten.

I just ran the figures...

If *every single* lightbulb created worldwide in a year was an incandescent bulb, they'd use about 10% less tungsten than one of those poles!

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Mushroom

Ha ha ha...

"space weapons are banned by treaty."

So are nukes, chemical and biological weapons. The good ol' USA have plenty of all three (and so does Britain, France and a few others)

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