Next- Thunderbird 1.
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- …
" 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.
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!
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.
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.
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.
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.
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
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.
> 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.
>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 .
"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.
+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.
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.
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.
>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.
>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".
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.
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.
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.
Not realy likely to be a problem either - almost every missile warhead produced today has at least a couple of kilos of tungsten wrapped round the HE. It is the material of choice for preformed fragments as it has the correct mass/hardness/price/penetration.
Plenty enough of it around at the right price to start making telegraph poles if anyone felt the need.
"accuracy measured in feet with existing technology"
Really? When stuff falls out of space the estimates of point of impact are generally given +/- a couple of hundred kilometres. I understand that a neat pole shape is more predictable than an irregular satellite, even so the main issue is that the altitude of the top of the drag-significant part of the atmosphere varies a lot in an unpredictable manner over very short periods of time.
Yep. They were certainly designed as bunker-busters, so they needed a high level of accuracy. It surprised me too. Perhaps the sheer density of it means its momentum over rules the aerodynamics? But I remember reading about its accuracy from a reliable source*
*a google search is throwing up plenty of questionable sources saying 25ft, but I can't find this reliable source. Don't purchase an Orbital Kinetic Bombardment system without doing your own due diligence.
I was referring to the fuel costs, which have to be lower thanks to this tech surely?
The missile is an accomplishment, I agree, it's just a shame it's primary use (or only use) would be for warfare.
The fuel tech I would hope would be sold to the rest of the world I would hope for general commercial and public use.
You will be happy. The best thing about this test is that it uses cheap-ish fuel, that is available at most airports (OK, lower grades are, this isn't too much of a stretch). But the big thing is energy density - drawings for hypersonic planes always show a cabin, but in reality with hydrogen the entire plane would be devoted to having to carry the fuel. But petrocarbons pack a lot more energy in a litre than hydrogen, so your commercial plane travelling hypersonically suddenly can actually carry PEOPLE, not just a huge hydrogen tank.
Will it ever go commercial? I don't think so, it will always be hugely expensive. And the failure mode of such a fast plane is pretty bleak - things would go wrong so fast, and probably so violently, that it's ultimate safety record for a large number of flights looks pretty suspect. It's one thing to have that happen in an SR-71, where at most two aviators are at risk, and have ejection seats. Its another to have that with 100 passengers with no hope of escape. Even Concorde was positively sitting still compared to this. There will be no "Salt Lake, Salt Lake...." radio transmissions, I suspect crashes with hypersonics will just be either a fireball or no wreckage at all...
"Will it ever go commercial? I don't think so, it will always be hugely expensive."
Its not just expensive, it *more* expensive ... when compared to a fully featured suite for conducting meetings over the internet or building a transcontinental rail link that can carry people in comfort rather than cubic-close-packed. The long-term future of mass transit by air is already doubtful.
"Its not just expensive, it *more* expensive ... when compared to a fully featured suite for conducting meetings over the internet or building a transcontinental rail link that can carry people in comfort rather than cubic-close-packed. The long-term future of mass transit by air is already doubtful."
Don't be silly. I can't go on holiday overseas* using the internet or a transcontinental rail link, and boats are too slow. Nor can I visit my relatives using any of those things. I'll always want/need to fly. Millions will agree with me. The long-term future of mass transit by air is ensured.
*The important part of the word 'overseas' is 'sea'.
"Don't be silly. I can't go on holiday overseas* using the internet or a transcontinental rail link, and boats are too slow."
When you are going on holiday, you aren't in *that* much of a hurry. I don't know the endpoints of your trips, so I'll use the ones I am personally familiar with: US to UK. That trip, on a normal aircraft, is about 5-8 hours (depending upon from where you leave the US.) For a holiday, spending basically one day getting there and one day getting back isn't a big deal.
For a business trip, it can be a big deal - you may be talking about a couple of days of meetings, and then you are looking at spending as much time traveling as working. Depending upon where in the food chain you reside, converting those 2 days traveling into half a day can be worth it.
Yes, converting those days into a few minutes to set up the link is even better, but for some types of business, being there in person is more valuable than being on the other end of a wire.
But I agree with the grandparent post: in *many* cases, the cost to use a proper teleconferencing setup, with cameras, shared whiteboards, good speakers and mikes, etc. is much less than traveling (and WAY less than traveling supersonic).
"The best thing about this test is that it uses cheap-ish fuel, that is available at most airports"
I think you'll find very few airports that can provide JP-7, and all of them will actually be US Air Force bases. JP-7 is the moderately exotic fuel used in the moderately exotic operating conditions of the SR-71, and now in the X-51... As you said, though, the thing about JP-7 is that like all other hydrocarbon fuels, it has a much higher energy-per-volume density(*) than liquid hydrogen, and doesn't require cryogenic storage.
(*) Per-volume is a useful measure of energy density for aircraft, but for rocketry, you also have to consider per-mass energy density, where hydrogen wins.
"It's one thing to have that happen in an SR-71"
Bill Weaver can tell you all about surviving the Mach 3+ disintegration of an SR-71. Ejecting wasn't an option, as the plane went from flying in good condition to a cloud of fragments in a couple of seconds, leaving the crew to take the scenic route to the ground... http://roadrunnersinternationale.com/weaver_sr71_bailout.html
"The US military may have finally achieved its goal of powering a sustained hypersonic flight on relatively ordinary jet fuel[....]"
For some values of ordinary - JP7 is NOT something you find at your local airport. It was the fuel that the SR-71 used; is almost impossible to light under normal circumstances (you can drop a lit match into it and it will extinguish the match, the SR-71 had to use a special hypergolic chemical to light it - tetra-ethyl-borane).
Still, being a liquid at normal pressures and temperatures, and not a cryogenic liquid like LH2, it is much easier to work with.
That step up from mach 3.5 ramjets to mach 5 scramjets must be a doozy considering its now taken 50 years and the scramjet is just now at the prototype stage. Just all the more amazing how quickly the SR71 (A12 could do mach 4 supposedly but probably safer to say mach 3.5 tops for either) was designed and ready for action and how state of the art it was at the time.
The Annie Jacobson "Area 51" book has quite a good history of the development of the U2/A12/SR71 with info gathered from the test pilots et all (until she wanders off into unsubstantiated fruit loop territory). The A12's were faster iirc just like the CIA spec U2's went higher then the USAF spec ones (due to USAF ones being painted and other little things)
Truly an amazing plane for its time. The 50 years is a moot point though, we could have scramjet airliners now but there is no demand so little money(relative to project size) gets spent on research. After concord no one was going to invest in fast travel and it was not a useful military option until the end of the cold war.
Probably not, as I recall the design of the intakes on the SR-71 was specifically designed to slow down the incoming atmosphere to below the speed of sound to allow ignition, unfortunately the design and theory doesn't scale up to higher mach speeds, hence it never going hypersonic. The scramjet is designed to negate the need to slow the incoming air to below the speed of sound, hence its much higher potential velocity, the problem is igniting the fuel in a superssonic and hypersonic stream of air, so probably nothing like it at all.
Firstly let's congratulate all concerned on a long awaited successful test ( providing Av Week are correct of course).
A history of Hypersonics at the Johns Hopkins APL suggests they first saw hypersonic combustion around 1962, so it really has been about 50 years to get to sustained free flight thrust vehicles.
The SR71 despite it's M3+ (the top speed can be worked out if you have a scale drawing and know the leading edge angles) side stepped the supersonic combustion problem by slowing the airflow in the nacelles and adding fuel as a subsonic ramjet. Above around M5.5 no fuel can add as much energy back into the flow that has been lost (into the airframe) as heat by just slowing the air to a useable speed, hence the ongoing interest in this problem.
JP7 is not the regular stuff in US military jets, that's (IIRC) JP4. In fact the hassle of setting up JP7 logistics was one of the cited reasons for shutting down the SR71 programme (It needed dedicated aerial refueling tanker aircraft as well because bad things happen when they mix). Less of an issue with missiles. For example US cruise missiles run on JP10, which is a single wholly synthetic compound at about $10/lb.
Precision guidance. I'd guess they will be dusting off the old plans for the Pershing II warhead. This used a radar head inside the casing at 2-4 RPM feeding a vacuum tube called a "correlatron" developed by Goodyear capable of near instant comparison of a bit mapped image of the target with a series of stills held on a few KB of ROM. At hypersonic speed you don't need very big control surfaces to manoeuvre. But anything hitting the ground at M5+ will leave a fair mark. I would guess something in the 10-100gram range (if hard enough) could punch through the roof of an armoured limousine for example and kill everything inside.
Hypersonic passenger travel. Reaction Engines did this work for the EU
Definitely the fastest way to get out of Brussels. :)
But they feel hypersonic flight is tougher than going to orbit. Ground to space is roughly 10mins climbing to thinner and thinner air all the time, but hypesonic flight could last hours with no simple way to dump the heat.
In climate modelling people say "climate is notweather," in aerospace the equivalent should be
"Cruise is not launch".
The bootnote points out that an ICBM would be cheaper and already exists.
However, an ICBM once launched is impossible to recall. At a certain point you can't even initiate self-destruct (like when there is a plasma sheath preventing radio communications ...)
This sort of weapon could be launched at the first sign of trouble but give the politicians an extra 30-45 minutes of negotiation time during which it can still be "called off". Which may be all that is needed. Depending on the situation, the simple launch of such a vehicle may be sufficient to resolve it.
I really view these hypersonic missiles as pure research. Someone at the military may be deluded into thinking it's useful but I think it really isn't... the materials research, control systems research, and so on, could trickle down into something useful, and would not need hypersonic speeds to be useful.
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