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 …
Still like blowing things up though
What you'll probably find is, that those engines don't have that many useful applications other than blowing things up quickly and far away. Oh, this wasn't covered by Lewis? Maybe I'm wrong.
THIS IS BOGUS ITS IMPOSSIBLE FOR ANYTHING TO TRAVEL FASTER THAN SOUND
Well, it's not... these are jet engines, i.e. air-breathers. Rockets carry their own oxidizers.
Well, rocket engineering, really. Which is a lot harder, as it turns out, than rocket science.
Get one of these for LOHAN
Lester has been suspiciously quiet about the new propulsion hasn't he?
LOHAN is designed to operate well into the upper atmosphere, I doubt there would be enough air for it to operate.
At Lohans operating altitude, when travelling at mach 6-8 there will be more than enough air passing into the engines for it to work. These engines are designed to work at these and higher altitudes.
LOHAN being lofted by a balloon won't be going mach 6.
Reports state that it reached a max altitude of 109,000ft, however it doesn't give the engines operating altitude.
Cool but for us mere peons it will only mean you get to your airport queue's faster.
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.
Much as I worry about the US I don't think they are comparable to North Korea....
'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?
There are already several ways of delivering WMDs that are already deployed. Rockets (ICBMs), Bombers, Cruise Missiles. What need is there for a new delivery system?
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.
"There are already several ways of delivering WMDs that are already deployed. Rockets (ICBMs), Bombers, Cruise Missiles. What need is there for a new delivery system?"
Orbital Weapons Platform.
Nuke them from orbit. Only way to be sure.
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.
Right. North Korea has a long history of invading sovereign states on paper thin pretexts, assassination and torture.
Erm, we were talking about....
Yes, which of these two countries is the more worrying.
Classic deterrence strategy for a small nuclear power faced by overwhelming external threats.
Too right. I've lost count of the countries North Korea has attacked, over the past few decades.
Only because its neighbors would roll it. NK would make Sadam look like a peaceful neighbor if they weren't so much less developed than their neighbors.
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.
We're talking about fantasies revolving around weapons of mass destruction; Do try to stay on topic, M'kay?
BTW: Your handle? Exactly correct.
Still hot, make sure you have the correct money!
Or British curries to Australia ! Still hot.
Why would you order your pizza from New York? If you want REAL pizza then you order it from its birthplace - Naples.
surely the island of Dominos?
The noise these things would make would have the the local of Naples running not for the hills, anywhere but the hills!
Pizza originates from Greece not Naples.
noise ??? at 50000 B52s are nearly silent to ground based listeners. at 80,000 SR71 is silent at Mach 3 to ground dwellers. At 109,000 at any mach these things would be effectively silent unless they were the size of a battleship.
my Broadband was faster.
Well, if they can do TCP/IP over carrier pidgeons...
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.
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.
Roughly 3 times as much energy by mass for hydrogen compared to kerosene. But liquid density roughly an order of magnitude less. So I'd assume the tank needs to be 3 times the size for the same energy content AND capable of holding cryogenic fuel.
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.
I think you are a bit confused. Aviation fuel is not a high explosive.
Therefore the speed of flame propagation < the speed of sound.
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?
"In terms of energy per kilogram, hydrogen is almost an order of magnitude"
Not as far as I know.
Hydrogen ~ 140 MJ/kg
Diesel ~ 45 MJ/kg
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.)
So this test was slower and used hydrocarbons rather than the much faster test with hydrogen. So all the brains in the world can't be arsed to develop ways to productionise hydrogen in safer ways and wean us off our carbon addiction which will run out one day anyway.
The point of hydrocarbon fuel is its energy density: more per tankful. It is easily synthesised from water and atmospheric carbon dioxide - plants do it all the time.
Beer ... because it contains a hydrocarbon!
"Beer ... because it contains a hydrocarbon"
Well it might have a trace but I think you mean carbohydrate
So SpaceX are barking up the wrong try by replacing H2 with Kero? Or are they taking the smart route, of cheap fuel with a higher energy density that requires less specialised storage?
Or, just perhaps, Chemist - Ethanol?
"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