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U.S. successfully flight-tests Raytheon hypersonic weapon
- timcavel 4y ago
- superkuh 4y agoHow long did it travel at hypersonic speeds while operating it's air breathing engine? I'm going to guess it was shorter than the thermal soak time of whatever material they were using for the inlet. The non-simple conical form of a scramjet means shockwave impingment has to happen in there somewhere and you can bet there's no material on Earth that's going to last more than a couple minutes. Hypersonic air-breathing craft that generate lift just aren't a reasonable thing to make. Hypersonic "gliders" and other rocket lofted things that get up to speed outside of the atmosphere and then just briefly travel through it make sense. But all this 'research' towards lift generating air-breathing hypersonics is just a trap to get nation states to dump money and effort.
- lallysingh 4y agoHow would you get the gliders above the atmosphere? Or rather, how would the military?
- detaro 4y ago> and other rocket lofted things
- tablespoon 4y ago> How would you get the gliders above the atmosphere? Or rather, how would the military? A rocket. I believe the those hypersonic gliders are ICBM warheads.
- knz 4y agoThey have options, including platforms such as https://en.m.wikipedia.org/wiki/Boeing_X-37 https://en.m.wikipedia.org/wiki/Boeing_X-37
- randomopining 4y agoSo why are they investing in it then?
- stevehawk 4y agoto make Americans feel better about the fact that Russia also has them. Plus any research in the field is likely to provide benefit elsewhere.
- superkuh 4y agoThe USA invested a lot in them in the 1960s/70s. That research pretty much conclusively found lift-generating thrust-producing in-atmosphere hypersonic craft weren't feasible. So the US let it drop. Fast forwards 50 years and other nation states are looking for ways to achieve ICBM-like performance without being mistaken for an ICBM. They foolishly fund these projects and then have to save face. The "hypersonics" are lauded as impressive "new" weapons for propaganda. The US, seeing this propaganda, has researchers that realize they too could use the funding again even if the end goal is silly. They could get in on the propaganda too. I assume the decision makers re: funding just don't understand the physics.
- dragontamer 4y agoNo one cares about 'just' a hypersonic per se. The world's militaries want a *homing* hypersonic missile, to avoid AEGIS missile defense and attack a US Carrier moving at 35MPH, trying to actively dodge out of the way. That means steering and thrust on the way down, likely staying at hypersonic speeds until it impacts the moving target. The world's militaries are trying to kill the US Carrier Strike Force.
- superkuh 4y agoThere's no need for air breathing, or other, thrust for this. Maneuverable reentry vehicles have existed for quite a while. We can call them hypersonics for nationalistic reasons but the speed is only achieved after the atmosphere and very briefly in it going down. If the goal is to avoid looking like an ICBM trajectory to avoid the other nation states thinking it's a nuclear attack then it makes sense. But it's still not achieveable for long periods of flight so the ICBM is required regardless.
- nautilius 4y ago> "[Hypersonic] Maneuverable reentry vehicles have existed for quite a while" I keep reading this comment on HN. It's like saying "What's the deal with Chuck Yaeger breaking the sound barrier, we've had supersonic bullets that do that for a long time". There is zero overlap between the two. Maneuverable reentry vehicles can wobble around a bit while falling, whereas the point of hypersonic weapons is maneuverability for a significant part of the trajectory.
- tomatotomato37 4y agoNot just maneuvearable, but actively maneuverable, aka able to sense some type of input inside the cone of visibly superheated air around it. This is different than an ICBM RV drifting around with RCS before re-entry or a cruise missile idling about before it's accelerated to attack speed. Unrelated but that's also why any talk of stealth with hypersonic is stupid; everything around the projectile is going to give off more of a signature than the projectile itself
- Robotbeat 4y agoSo just regeneratively cool that portion like you would in a rocket engine (or an ablative or whatever). No big deal. Why this assumption that aerospace engineers are just idiots and they didn’t think about designing it to last longer than thermal soak?
- superkuh 4y agoYou can read the full reasoning here as it is too long to fit in a HN comment: https://exrocketman.blogspot.com/2022/06/about-hypersonic-vehicles.html https://exrocketman.blogspot.com/2022/06/about-hypersonic-ve...
- Robotbeat 4y agoRead it. None of that justifies the absurd claim that no materials exist and therefore they can only fly to thermal soak.
- nautilius 4y agoYour only comment about heat load is that it's the most important factor and then I should look at some picture. There's zero reasoning in that picture.
- WillPostForFood 4y agoHow long did it travel at hypersonic speeds 300 miles was the reported test distance. https://www.darpa.mil/news-events/2022-07-18 https://www.darpa.mil/news-events/2022-07-18 After release from an aircraft, the first stage boosted the vehicle to the expected scramjet ignition envelope. From there the missile’s Northrop Grumman scramjet engine fired up and propelled the cruiser to speeds greater than Mach 5 (five times the speed of sound) for more than 300 nautical miles and reaching altitudes higher than 60,000 feet.
- Ajedi32 4y agoSo ~2 hours then: https://www.wolframalpha.com/input?i=300+nautical+miles+%2F+mach+5 https://www.wolframalpha.com/input?i=300+nautical+miles+%2F+...
- jmgrosen 4y agoI think more like 5.5 minutes: https://www.wolframalpha.com/input?i=300+nautical+miles+%2F+%28mach+5%29 https://www.wolframalpha.com/input?i=300+nautical+miles+%2F+...
- Ajedi32 4y agoYeah, I just realized that number seemed way off and was about to edit my comment. ~5 minutes is correct.
- nradov 4y agoThe British are still investing in development of the Reaction Engines SABRE air-breathing hypersonic engine concept. They have a novel design to address engine cooling but it's unclear whether it will really work. https://reactionengines.co.uk/advanced-propulsion/sabre/ https://reactionengines.co.uk/advanced-propulsion/sabre/
- cpursley 4y agoMeanwhile Russia is successfully fielding hypersonic weapons in it's invasion of Ukraine. Additionally, US air defense tech is severely lacking compared to Russia's multilayered systems. Yet US spends much much more. Where is the money going?
- Nick87633 4y agoThis reads a lot like propaganda unless you bring in some sources and numbers
- dsr_ 4y agoAlso, hypersonic weapons are not new. The new part of this is "air-breathing", i.e. not carrying an oxidizer.
- dragontamer 4y agoHow many HIMARS rockets are the Russian defense system shooting down? Given all the ammo dumps on fire this past week, it is clear that the Russian air defense system fails at subsonic rockets, let alone supersonic or hypersonic. We'll seriously discuss air defense the moment Russia can deal with cheap rockets / Missiles (HIMARS or Neptune). But Moskova sank and now S300 /S400 systems are getting wrecked. The Russian systems have proven to be a complete joke to a degree no one expected. Against the Russian adversary, it has become clear that hypersonics are not needed. Neptune (subsonic sea skimming cruise missiles) and HIMARS (ballistic semi-guided subsonic rockets) are all that's actually required.
- vasac 4y agoThat doesn't work the way you think it works. Even Israel, with limited territory that it wants to protect isn't successful in 100% of times. Currently air defense of all military powerful countries is able to defend against limited attack of ballistic missiles, not against every single rocket that MRLS spews in a span of 20 seconds. btw Iran rocked US bases in Iraq just fine with not terribly modern rockets.
- dsr_ 4y agoIs the only point of these to evade treaty requirements on ICBMs?
- dragontamer 4y agoMissile defense systems seem able to defend against normal rockets. Hypersonics beat the defense by flying faster. To defend against a hypersonic missile, you yourself need to build a hypersonic air defense missile. -------- I still don't know if it's a practical weapon though. It seems like normal missiles / rockets are working vs Russia (Moskova and these ammo dumps this past week). Maybe Chinas air defense is a worthy adversary. But it's clear we ain't building these for Russia...
- rich_sasha 4y agoI believe modern ICBMs are not really so defensible against. Perhaps some of the simpler ones like North Korean or Iranian ones. If nothing else, dropping a fast projectile from space is an easier way to create hypersonic speeds than using an air-breathing engine, and there's nothing stopping you implementing manouvreability into these (and I believe that's what modern ICBMs do at the end). US has missile defence programs but they don't seem like a huge priority in the grand scheme of things (just an amateur defence follower here). The main thing about hypersonic weapons seems to be that others have them and US don't so it better close the hypersonic weapons gap. I suppose you never know where the technology might lead. But for example, during the Cold War, Russia had weaponry specifically designed for destroying US carrier groups, which were thought to be a major threat. Whereas US didn't need such weapons, since Russia didn't have carrier groups. So there can be a bit of asymmetry built in from the get-go.
- waffleiron 4y ago> Hypersonics beat the defense by flying faster. ICBMs go hypersonic speeds. These "hypersonic" weapons don't fly a ballistic trajectory and are therefore: - Easy to discriminate from ICBMs (e.g. potentially not start a nuclear war if you need a conventional "fast" weapons). - Later/harder detectable, because they fly lower it can be more difficult to detect them. - More manoeuvrable. - Harder to intercept, an ICBM doesn't always fly at top speed, and travels in a predictable arc. - Fancy / cool sounding, other countries have them, so none of the major players want to feel left out.
- robertlagrant 4y agoWhat they forget is an air-breathing Tom Cruise already beat Mach 10.
- rsutherland 4y agoHe is limited in supply so we cannot load up missiles with Tom more than once, unfortunately. It has been considered
- H8crilA 4y agoFyi, there are hypersonic ramjet tube artillery shells being developed by the Norwegians. Pretty cool stuff, great range extension and you don't have to worry that much about engine unstarts (some shells will simply miss, by a lot, if they unstart). And there is no problem with bringing the ramjet to the minimum operational speed, the howitzer does that for you. Link: https://www.nammo.com/story/the-range-revolution/ https://www.nammo.com/story/the-range-revolution/
- tim333 4y agoCool gizmos but those are supersonic (~mach 3) rather than hypersonic (5+).
- openasocket 4y agoQuick reminder that hypersonic weapons are not in any way new. Most ballistic missiles reach hypersonic speeds, the V2 rocket used by Nazi Germany in WW2 very nearly reached hypersonic speeds. ICBMs generally go above Mach 20. What is new here is an "air-breathing" cruise missile traveling at hypersonic speeds. It's not traveling in a ballistic arc, or gliding after a boost phase, but actually reaching hypersonic speeds "under its own power" so to speak. No weapon actually fielded today does that, though several countries are developing it (including the US, Russia with the Zircon missile, and India with the BrahMos-II).