Now that is rocket science!
Still like blowing things up though
The successful test launch of the hydrocarbon-fuelled scramjet HIFire 2 by the US brings mankind a step closer to practical travel at over five times the speed of sound. Reliable hypersonic transportation could revolutionise trips to space and across the globe, but sustained flight at such speed is difficult: several test …
North Korea gets penalized for firing a rocket but when America does it (after dropping 2 nukes on civilians, has a long history of hydrogen bomb and nuke testing plus invading a country under false pretenses), nobody cares that this technology can (and will) be used in WMD's.
I get it though, really I do. I just wish big countries would stop being bullies, grow up and play nice together before we are all blown to smithereens.
ask the japanese civilians abducted for NK spy program training if NK attacks other countries. NK ship carrying addictive drugs off Oz also. Social attacks are attacks, just not with guns.
SK also has a slight problem with attacks from their neighbour. The yanks have problems as a culture, but aside from their multinationals, mad bankers and deluded talk/radio show hosts, have been remarkably restrained as a world power.
'Nobody cares that this technology can (and will) be used in WMD's'.
You're right, nobody cares. But then when (from that perspective) the story is 'country which already has ICBMS that can kill anyone anywhere on the planet in minutes tests new rocket which is slightly slower and shorter range' they're not exactly likely to are they?
So what is the military use? I'd have thought that if they can make the technology reliable, it's for delivering conventional explosives onto mobile targets ... this thing may be too fast to intercept and too fast to move when you spot it coming.
But also a good step towards Earth to Orbit without needing huge expensive rockets to lift fairly small payloads. Ultimately, this might lead to a genuine spaceplane, if HOTOL doesn't get there first .
There is a minor, insignificant detail here.
In USA there is a well known power structure in front of the "Launch" button. At least that is the case most of the time. It is more or less clear what drives it and what are the circumstances when it may push it. Ditto for Russia & France. It is less so for China, but even in that case we can do some extrapolations based on known facts and past behaviour. Ditto for India though I'd rather not go into what is the "power structure" there and what drives it.
So when one of these countries tests the latest S400 missile, the latest scramjet or just fires a plain old ICBM like India did recently that does not really upset the balance. It is, yeah, so what, yawn, news at 10...
The difference between these and North Korea rulers however, is that North Korea Kim dinasty are like a macaque with a hand grenade. You have no f*** idea where he will throw it and will he pull the ring or not before throwing it. To make matters worse you have no idea who really the macaque in charge of the troop is on this particular day. In addition to that if you extrapolate from past behavior and known facts your most "happy thought" will be that the macaque has been bitten by a rabid dog more than once.
Yes, I agree with you. Hence me stating that I understand the situation.
I am watching 'Dr. Strangelove' as I type and I feel history is repeating itself. The Communist threat then is the North Koreans' now. I believe NK people are being oppressed, starved and ruled by a puppet master hiding behind a cloak of a giant military force ruled by but a few, but I am also aware of the continuous negativity in which NK is being portrayed. As I have never visited NK, all information I have been receiving has been from sources keen on making NK look like the worst place on earth.
A bit like Communist Russia was portrayed during the cold war, don't you think?
Before you ask, 'yes' I have seen the BBC docu on NK and I feel deeply for the people, but in war those same people would fight harder for their country then any other. They can't help it...
The USA has had nukes for almost 70 years. If your paranioa were based on anything other than rather dated groupthink, you'd stop to notice that there's been precisely two combat uses of nukes, and that at the very end of a long and devestating declared war.
Hardly the things of which proper paranoid fantasies are built. Do try harder, next time.
How does current hydrogen fuel usage compare to hydrocarbons in terms of energy per stored kilogram, or on a stored volume basis?
Re. supersonic combustion: I thought that all 'jet' engines had supersonic airflow in the combustion chamber, which is why the burning fuel doesn't 'explode' out from the front of the engine.
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There's supersonic flow out of the chamber, but with the exception of scramjets there's no supersonic flow into it. The output of the compression stage of a turbojet or ramjet or whatever is high pressure subsonic air. Its that high pressure that stops any sort of blowback.
Hydrogen is the best fuel (i.e. highest specific impulse) when measured by mass (per kilogram) which is why it is commonly used for heavy lift and super-heavy lift rockets. However it is relatively poor when measured by volume (per m^3) since even liquid hydrogen has a very low density (about 67.8 kg/m^3 - compare to water which is 1,000 kg/m^3). Also liquid hydrogen tanks typically need lots of insulation, while leaks (due to the small size of hydrogen molecules) are a major problem. That's why rockets using liquid hydrogen have their fuel tanks topped off right to the point of engine ignition.
In terms of energy per kilogram, hydrogen is almost an order of magnitude better that hydrocarbon fuels. But if you add the pressure container, that advantage shrinks significantly. In "Energy Environ. Sci., 2010, 3, 689-699", the authors claim that you can drive the same 500 km distance with either 33 kg Diesel (+10 kg tank) or with 6 kg hydrogen (+120 kg container).
If you want to get rid of the pressure container, you have to liquefy the hydrogen by seriously cooling it down and then you should launch quickly before the fuel warms up. But the foam insulation on those tanks can be a bitch (see Columbia disaster).
Was that what you were looking for?
Thank you for those informative replies. That's one of the reasons I enjoy El Reg :)
(I had thought that the fuel-air mixture in a 'jet' combustion chamber experienced a 'continuous explosion' effect where the flame front travelled at the speed of sound. Apparently not, or maybe the compressor output air speed is pretty high... some combination.....whatever.)
Soyuz and most '60's rockets used Kerosene.
SpaceX are using RP-1 as it's cheap and as the technology is well proven and low risk.
The cost of developing a reusable cryogenic engine is much higher, for a couple of percent mass fraction.
Additionally the rocket would need to be much larger to contain the LH2 required.
"to productionise hydrogen in safer ways and wean us off our carbo"
Producing it safely is not the problem - getting the energy to produce it is.
Whatever way you make it needs energy - 2H2+O2 -> water +~~600kJ/mol So you need at least that and indeed a lot more to produce hydrogen gas. So >1MJ to produce about 70 litres of hydrogen gas.
Distribution and storage are also problems
Target... Target... Target...
Roger that scan I’ve got a contact and locked on
Something’s going on at the jack slinger
Target... Target... Target...
Let’s jet out, we’ll cruise at hyperspeed
I got the beat, I got the beat
And that’s all we need – check it out!
The driver behind this is for the Amerikans to have a weapon system that can strike fleeting precision targets with conventional warheads launched from "safe" areas (USA or from warships) at global distances and in short flight times.
Its known as the Conventional Prompt Global Strike (CPGS)... go google it - FAS has a nice docco on it.
There are a number of reasons why they need this and can't use ICBM's - the main one being that characteristic ICBM launches tend to "un-nerve" some "other folks" and also the technology in ICBM's is restricted in numbers by START/SALT.
So what they need is a non-ICBM system that can rain small (think hellfire or maverick missile) sized warheads onto a selection of folks driving Toyata Hi-Lux's in a desert somewhere at a few minutes notice when a satellite either sees them or hears them on the phone.
Its cheap, its low risk (well, no amerikans will die) and it puts the fear of Allah into their enemies...
Really? I mean faster global travel would be nice for the (sadly) rare occasions I go on my hols, but I'm not convinced I'd enjoy the acceleration!
It definitely seems more like a military "thang". They might see some use from drones where speed is vital (Al Dave is spotted in his convoy headed into town - they want to make sure Al Dave doesn't get more than 100yds up the road before he is killed by "insurgents" to avoid press conferences...err... killing civies)
I have two points to make concerning lack of crucial detail in the article:
a) Exactly how many cartons of off-milk would have to be dumped down drains to equal the greenhouse emissions of this scale model of Thunderbird 1?
2) Was there or was there not a Playmobil pilot on board during the test, and if not, does it represent an exclusionary policy on the part of the agencies involved (no Playmonauts need apply?).
Okay, three points.
Why are we wasting time with energy intensive lift technologies?
Adequate funding should be provided to those searching for an economical way to produce Cavorite on an industrial scale. The spin-off benefits to this research are obvious to all: it would revitalize the sagging railway buffer market and revolutionize the crane industry, besides making flying cars a trivial exercise in re-engineering current marques. Elevator technology would be given a much-needed shot in the arm and emergency skyscraper escape harnesses would be a new "must have" accessory for the busy Wall Street executive.
But no. NASA and the industrial-military complex remain mired in the 1950s vision of Von Braun. Probably because Cavorite was invented by an Englishman.
I wonder how many other wonders of science have been lost to jingoism?
NASA Aeronautical history book 2, a free PDF download from nasa.org... about 1/3 of a really big book is devoted to Supersonic Cruise... a joint NASA, USAF, DARPA project is extending this into speed levels to clear the planet... basic shape, fuels, and engine research is progressing... someday...