7 ms·
Hypersonic flight: A new fuel for jets and missiles is on the cards
- sudosysgen 5y agoRussia and the USSR have already been working on such fuels, which are due to be used on the Zircon hypersonic missiles. In order to achieve the same goals while avoiding the safety issues of boron fuels, the Decilin-M fuel for the Zircon missile is thought to use engineered hydrocarbons (the exact composition is unknown) with polyethylene to thicken the solution with aluminium nanoparticle added.
- david-gpu 5y agoWikipedia has an article about this, for those interested. https://en.wikipedia.org/wiki/3M22_Zircon https://en.wikipedia.org/wiki/3M22_Zircon
- jcun4128 5y agoCurious, says range is at most 400mi if used ballistically. I wonder even at Mach 9 can a laser stop this thing or would ships just use railgun/lasers against each other? Maybe it's surface to ship.
- wongarsu 5y agoThe problem with ship-to-ship laser combat is that line-of-sight only a couple kilometers. Two objects mounted in 20m height can only see each other for 36km. Railguns are a lot more likely, but I think we still don't have "barrels" that survive firing more than a couple shots before replacement.
- mc32 5y agoCan they bounce the beam off of a sat or flying object?
- wongarsu 5y agoMaybe a good use for quadrocopters or other low-cost drones. If you use a satellite, you might as well put a larger concave mirror on it to focus sunlight. A nearly 100 year old weapon concept that luckily never happened [1] 1: https://en.wikipedia.org/wiki/Sun_gun https://en.wikipedia.org/wiki/Sun_gun
- deleted 5y ago[deleted]
- sudosysgen 5y agoIf your lasers can be reflected easily by mirrors, then the missile will simply be painted with a mirror coating.
- chrisseaton 5y agoYou need ballistic weapons to get around the fact that the surface of the earth is curved.
- bernulli 5y agoThe key point of hypersonic weapons is that they are maneuverable.
- chrisseaton 5y agoRight - ballistic or guided - I really meant kinetic as opposed to energy weapons like lasers.
- jhgb 5y agoIf it's heading at you at Mach 9, just dump a load of BB pellets against it.
- rbanffy 5y agoUnless you dump a significant amount of BB pellets, you’ll still have high-speed missile parts flying in your direction.
- jhgb 5y agoAt the altitude at which you can reasonably fly at Mach 9, destroying the aerodynamics of the vehicle means that you have low-speed parts of a formerly high-speed missile flying in your direction. And unless the interception happens in the zenith, whence they could just fall down on you, they won't keep flying in your direction for long.
- sudosysgen 5y agoI don't understand your description. Where do you want to put shrapnel in front of the missile? Because you're not going to be able to do it until shortly before impact. Also, flight at Mach 9 can be done at low altitudes. Just not for very long and only once.
- pie420 5y agoThose high speed middle parts will get slowed down by insane air resistance down to sub Mach 1 speeds in a couple hundred meters would be my guess. Non-aerodynamic, non-propelled middle chunks are not a threat to battleships, especially compared to Mach 9 missiles.
- sudosysgen 5y agoHow do you shoot projectiles at a hypersonic missile within a hundred meters of impact? Also, I don't think you appreciate the amount of energy in a 5 ton missile going at hypersonic speeds. For it to slow down within 200m, it needs to basically stop in 0.075 seconds.
- david-gpu 5y agoNon-paywalled mirror: https://archive.is/lT5dT https://archive.is/lT5dT
- grouphugs 5y agoit's a really bad time for new weapons
- seiferteric 5y agosounds like https://en.wikipedia.org/wiki/Zip_fuel https://en.wikipedia.org/wiki/Zip_fuel
- adeelk93 5y agoThat is indeed what the article says
- knolan 5y agoFor anyone interested in the development of rocket propellant and related fuel I’d highly recommend ‘Ignition!: An Informal History of Liquid Rocket Propellants’ by John D. Clark.
- nyankosensei 5y agoI also recommend ‘The Green Flame’ by Andrew Dequasie. It’s the fascinating personal story of a chemist embarking on a new career and ending up working with borane fuels.
- tim333 5y agoStart of the chapter on it: >Fifteen years ago people used to ask me "What is an exotic fuel any- way?" and I would answer "It's expensive, it's got boron in it, and it probably doesn't work." I had intended, originally, to entitle this chap- ter "The Billion Buck Boron Booboo," but decided against it on two grounds. The first was that such a title might conceivably be consid- ered tactless by some of the people who authorized the programs con- cerned. The second reason is that it would not be completely accurate. Actually, the boron programs did not cost a billion dollars. It just seemed that way at the time.
- SiempreViernes 5y agoIt's funny how articles about hypersonic weapons always talk about their speed when the defining property is manoeuvrability; Obviously you can't turn very well if you go super fast, so the solution is to go slower: hypersonic missiles aren't actually the fastest missiles around.
- rbanffy 5y agoIf you know where your target will be, you don’t need to manoeuvre too much. If you are getting there on Mach 9, the target will very much be wherever it was when you launched.
- bernulli 5y agoBut you also don't want your target to know that it is being attacked to prevent countermeasures.
- rsfern 5y agoThe current sort of arms race around hypersonics is precisely because there are no good currently existing countermeasures for a missile traveling at like Mach 10. I’m sure it’s being worked on, but there’s a lot of effort going into the mutually assured destruction short of strategy.
- SiempreViernes 5y agoA car going 30 km/h clears the 30m blast radius of a 900kg bomb in about three seconds, and the 340m fragmentation radius in about 40 seconds. This means that to hit a moving target at Mach 9 (or about 3 km/s) you need to launch your 11m long rocket within either 9 or 120 km depending on the desired probability for a kill. As a reference, an aircraft carrier can go over 50 km/h, the Chinese hypersonic weapons go about 1.7 km/s and have a range of at least 1000 km. How does that work out you wonder? Simple, they put nukes on their hypersonic missiles.
- elric 5y ago
- pfdietz 5y agoThere is an interesting boron fuel combination that would be useful for an air turborocket. (See https://en.wikipedia.org/wiki/Air_turborocket https://en.wikipedia.org/wiki/Air_turborocket for what that is.) The combination is diborane (B2H6) and hydrazine (N2H4). These react to form boron nitride (BN) and hydrogen. This reaction is exothermic and by itself would give an Isp of maybe 250 s, IIRC. The gas is hydrogen rich, and would be great for feeding into the air turborocket, or into a scramjet, for combustion with air.
- ricardobeat 5y agoThe original research was suspended in part due to how dangerous these fuels were, hydrazine doesn't sound like a very promising option being extremely toxic and flammable.
- bernulli 5y agoSurely the Isp, i.e. thrust per propellant weight flow rate, would have to be much higher for that air turborocket? 250s is not that great already for a rocket that has to carry all of the propellant; the big advantage of an airbreathing engine is that only a fraction of the accelerated massflow is propellant.
- msandford 5y agoI believe that's the ISP of the initial reaction that makes a hydrogen rich gas that you feed into your air breathing thing. That's how it reads to me anyhow. You'll likely get extra ISP from the hydrogen/air combustion too.
- pfdietz 5y agoThat's correct; it was the Isp of that combination if just used in an ordinary rocket engine, not an airbreathing engine.
- deleted 5y ago[deleted]
- mikewarot 5y agoHave they solved the erosion problems with it that lead to it being dropped in the 1960s?
- jjk166 5y agoThere are a lot of issues that led to these fuels being abandoned the first time around, most of which are unavoidable. 1) Boron Carbide and Boron Nitride particles form in the exhaust. These are extremely abrasive, destroying downstream engine components. They also make the exhaust plume highly detectable over long distances - think of the particles like soot from a coal burning ship. 2) The fuels are extremely corrosive, and thus you can't leave a tank full with them, and even when you do fuel up, you can't run on pure boranes, you need to mix them with other fuels. This means you can't keep a boron fueled missile on standby, so its speed advantage is rendered moot except for surprise first strikes. Further, in diluting the fuel the performance gains are reduced. 3) Boron based fuels suffer from incomplete combustion, dramatically reducing real performance below theoretical values. 4) Manufacturing and storing these chemicals is incredibly dangerous and expensive. One of the major reasons for the initial program's abandonment was that a production plant exploded. These safety concerns were damning in the age of atmospheric nuclear tests, one can imagine the difficulty of production in a modern regulatory environment. In short, boron based fuels offer only questionable performance gains at very high economic, technical, and human costs. I won't say there is no future at all for them, but the idea that they are the fuel of the future is laughable.
- carapace 5y agoIt's not Plichta's silane fuel. Instead of hydrocarbon use hydrosilicon. Thought to be unstable (like "big bada boom" unstable) Peter Plichta discovered that "Silanes with chains of seven or more atoms of silicon per molecule are stable and can be pumped and stored very much like gasoline and other carbon-based liquid fuels." http://www.rexresearch.com/plichtasilane/plichta.html http://www.rexresearch.com/plichtasilane/plichta.html They burn nitrogen and are said to make lightning instead of flames. > The combustion process of hydrosilicons is fundamentally different from the exclusively oxygen based combustion we know from burning hydrocarbons. In a sufficiently hot reaction chamber, silanes separate into atoms of hydrogen and silicon, which immediately mix with the oxygen and nitrogen of the air. The hydrogen from the silanes and the air's oxygen now burn completely leaving only water vapor, bringing the temperature of the gases close to 2000 degrees C. > Since there is no more oxygen, no silicon oxide can be formed in the following phase. What happens instead is an extremely energetic reaction of the 80% nitrogen in the air with the silicon atoms present, that forms a fine powder called silicon nitride (Si3N4).