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Science

Oblique Wave Detonation Engine May Unlock Mach 17 Aircraft (newatlas.com) 131

Posted by BeauHD from the world-first dept.
schwit1 shares a report from New Atlas: UCF researchers say they've trapped a sustained explosive detonation, fixed in place, for the first time, channeling its enormous power into thrust in a new oblique wave detonation engine that could propel an aircraft up to 17 times the speed of sound, potentially beating the scramjet as a hypersonic propulsion method. [...] Rotating detonation engines, in which the shockwaves from one detonation are tuned to trigger further detonations within a ring-shaped channel, were thought of as impossible to build right up until researchers at the University of Central Florida (UCF) went ahead and demonstrated a prototype last year in sustained operation. Due for testing in a rocket launch by around 2025, rotating detonation engines should be more efficient than pulse detonation engines simply because the combustion chamber doesn't need to be cleared out between detonations.

Now, another team from UCF, including some of the same researchers that built the rotating detonation engine last year, says it's managed a world-first demonstration of an elusive third type of detonation engine that could out-punch them all, theoretically opening up a pathway to aircraft flying at speeds up to 13,000 mph (21,000 km/h), or 17 times the speedThe UCF team claims it has successfully stabilized a detonation wave under hypersonic flow conditions, keeping it in place rather than having it move upstream (where it could cause the fuel source to explode) or downstream (where it would lose its explosive advantage and fizzle out into a deflagration). [...] Where a detonation typically lasts only a matter of micro- or milliseconds, the UCF team managed to sustain this one experimentally until the fuel was turned off after around three seconds. That's long enough to prove the device works [...]. The paper is open-access at PNAS.
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Oblique Wave Detonation Engine May Unlock Mach 17 Aircraft More

Oblique Wave Detonation Engine May Unlock Mach 17 Aircraft

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  • Hypersonic flight is the application du jour (Score:5, Interesting)

    by sonoronos ( 610381 ) on Friday May 14, 2021 @02:18AM (#61383278)

    A year or two ago, the applications for this type of engine were reported as âoefuel savings for warshipsâ and as a replacement engine for space launch vehicles.

    The US military has been pushing the hypersonic weaponry angle lately in the last few months. Virtually anything in the media you will read regarding mach 3+ flight is almost totally geared towards hypersonic weaponry in flight.

    I think the technology is interesting, but it is rather funny to see it being advertised as a solution to the US military problem du jour, as if the target audience were Janes readers.

    Dear national media: some more information about the actual technology, please? The applications are obvious.

    • Well that is the way battles are fought by the super-powers now.

      We shoot at you like real men, from miles and miles away, and the shit coming at you cannot be countered at the speed its coming in at.

      • Re: (Score:3, Interesting)

        by Anonymous Coward

        Pretty sure if you can work out it's trajectory (very simple), and detonate something in front of it (very simple) that it's not going to get it's shit together at the speed it's moving at, to be able to get out of the way.

        In a way, the faster you go, the easier a target you become because you simply can't change direction fast enough.

        • Re:Hypersonic flight is the application du jour (Score:4, Interesting)

          by luis_a_espinal ( 1810296 ) on Friday May 14, 2021 @07:33AM (#61383656)

          Pretty sure if you can work out it's trajectory (very simple), and detonate something in front of it (very simple) that it's not going to get it's shit together at the speed it's moving at, to be able to get out of the way.

          In a way, the faster you go, the easier a target you become because you simply can't change direction fast enough.

          Holy crap dude, you suck at physics. You can't work out the trajectory because you can't detect the bloody thing (and thus calculate the trajectory) until it is too late. We just don't have that kind of technology (so it is not "very simple.") So, no, we can't just dodge it Neo style.

          • Re:Hypersonic flight is the application du jour (Score:4, Interesting)

            by rossdee ( 243626 ) on Friday May 14, 2021 @08:49AM (#61383858)

            "you can't detect the bloody thing (and thus calculate the trajectory) until it is too late."

            Thongs that move that quickly tend to be not stealthy. The meteor like trail could be spotted by satellite.

            • Re: (Score:3)

              by flink ( 18449 )

              "you can't detect the bloody thing (and thus calculate the trajectory) until it is too late."

              Thongs that move that quickly tend to be not stealthy. The meteor like trail could be spotted by satellite.

              Spot it yes, launch and accelerate an interceptor in time to meet it? Doubtful.

              • I think it may be possible if one establishes a grid of stationary countermeasure-launching platforms, creating a mesh above the protected area. The density of the mesh would be a function of the countermeasure acceleration and final velocity figures, in relation to the same of the incoming missile. Further, deviations in the incoming missile's flight path, such as through 'piloting,' would necessitate a tightening of the mesh.

                An advancement of this tech would be non-stationary. It could be the function o
              • In the 1970s we had this thing called Sprint, an anti-ballistic missile designed to intercept re-entry vehicles as they dropped into the atmosphere. It could accelerate to Mach 10 in five seconds, which was necessary because the RVs only left a window of a few seconds before it reached its target. So, not only is it possible, but we've had the capability for a long time.

              • Unless the interceptor itself is hypersonic. Which is why the Navy has built a sub-caliber saboted shell for their 5 inch guns that can achieve hypersonic velocities. The guidance systems were actually built for the Navy's Dhalgren division's railgun.

        • the easier a target you become because you simply can't change direction fast enough.
          That is nonsense.

        • Re: (Score:2)

          by sjames ( 1099 )

          The faster it's moving, the shorter your window is to explode something at the right time to destroy it. At mach 17, you don't even have time to finish saying "OH SHIT!" before it hits you.

          • Re: (Score:2)

            by suutar ( 1860506 )

            At mach 17, you probably don't even need much of a warhead, and a solid slug is going to be deflectable but difficult to completely neutralize.

            • Re: (Score:2)

              by suutar ( 1860506 )

              I went and looked up some numbers. Mach 17 is about half of escape velocity, so a slug of metal at that speed is going to have about 1/4 the energy of one dropped from orbit... and orbital tunsten rods are supposedly comparable to nukes.

        • Can you detonate something in front of a speeding bullet? Or place anything in front of it, to protect the target? According to https://en.m.wikipedia.org/wik... [wikipedia.org] the fastest reach speeds of 1700m/s, and Mach 17 is more than 3x that at close to 6000m/s.

        • Re: (Score:2)

          by djinn6 ( 1868030 )

          Actually you can change your sideways velocity just as quickly as if you were moving slowly. A airfoil deflection that causes a 10 g sideways acceleration causes your velocity to change by 98 m/s/s in no matter how fast you're moving. You'll be hundreds of meters away from your original predicted location in a few seconds in all cases.

      • Re:Hypersonic flight is the application du jour (Score:4, Insightful)

        by arglebargle_xiv ( 2212710 ) on Friday May 14, 2021 @06:32AM (#61383560)
        Actually it's "we spend twenty years and umpty bazillion dollars trying to develop something of marginal practical advantage over what we've already got which may or may not ever see the light of day but which will be so expensive once fielded that it'll require the personal approval of the president every time one is used". In the meantime a bunch of guys who dropped out of school at age 14 will be blowing up US troops with recovered explosives from US bombs that failed to detonate. But hey, shiny flashy shiny!

        • Re:Hypersonic flight is the application du jour (Score:5, Insightful)

          by flink ( 18449 ) on Friday May 14, 2021 @10:11AM (#61384148)

          If there is anything the last 20 years should have taught the powers that be in the US it is that unless you are willing to wage total war and commit genocide, you cannot defeat an insurrection from the air. You'd think we would have learned that from Vietnam, but no, they are determined to keep trying.

          Maybe spend some of that DARPA R&D money on decent HUMINT and stop engaging in foreign policy that generates so much murderous rage. But it is easier to hand a kid sitting in a shipping container in North Carolina an XBox controller and have him blow up another wedding, thus ensuring that the forever war continues.

          • Re: (Score:2)

            by leptons ( 891340 )
            This is all in response to Russia announcing they have a hyper-sonic nuclear weapon, which the US currently does not have. It's the typical arms race thing.

            • Re: (Score:2)

              by vlad30 ( 44644 )
              Russia learned from Reagan Don't have to go to war just send them broke chasing whatever we announce, OTOH if this works it could be a good countermeasure to scarmjets

      • It has always been US policy to have the best trained, best equipped people on the battlefield. Let the other nations throw human waves against each other. Your nostalgia for this is disturbing.

        And don't say unilateral peace. Last time I checked half the world wasn't, and was expanding.

      • Well that is the way battles are fought by the super-powers now.

        We shoot at you like real men, from miles and miles away, and the shit coming at you cannot be countered at the speed its coming in at.

        This concept is the basis of Mutually Assured Destruction, and has thus far staved off World War 3. While any of the super-powers can destroy the others anytime they choose, there is no viable defense -only an unstoppable retaliation.

      • "Those COWARD GAULS fighting with SLINGS from a DISTANCE"

    • Re:Hypersonic flight is the application du jour (Score:5, Interesting)

      by thegarbz ( 1787294 ) on Friday May 14, 2021 @04:09AM (#61383408)

      I sincerely doubt this has any practical benefit in weapons. It would be many orders of magnitude to complex and expensive to be practical. Even the American MIC couldn't afford these.

      Scramjets has the benefit of high speeds and incredible simplicity and are far more likely to find their way into hypersonic weapons. Also there's really a question if there's any practical benefit to a missile that goes Mach 17 over Mach 10.

      • The big race at the moment is to develop delivery systems that can target anyone, anywhere within not hours but minutes. A 70% increase in speed is not to be sneezed at. Mach 17 is around the equator in two hours.

        • Re: Hypersonic flight is the application du jour (Score:5, Interesting)

          by njvack ( 646524 ) <njvack@freshforever.net> on Friday May 14, 2021 @10:37AM (#61384256)

          The big race at the moment is to develop delivery systems that can target anyone, anywhere within not hours but minutes. A 70% increase in speed is not to be sneezed at. Mach 17 is around the equator in two hours.

          One alternative they might consider is some kind of weapon launched on a rocket, following a ballistic trajectory to its target. Since we can launch things all the way into orbit, and those rockets go very fast, it's a reasonable guess that these could deliver missiles all the way across continents very fast too. I don't know what you'd call them, maybe Internationally Cheered Blammo Munitions, or ICBM for short, or something.

          I honestly don't get why the military keeps working on new hypersonic missiles when WE ALREADY HAVE HYPERSONIC MISSILES and have had for the last 50 years. It's not like our adversaries are going to look at this and say "well, ICBMs were bad and scary but these new launchers are fine because they're airbreathing, we sure won't resume our arms race for those."

          Yes, the technology is cool, but people keep talking about these like they're going to be deployable weapons that somehow get around the geopolitical problems of existing ballistic missile systems despite having awfully similar capabilities. Or that they're going to be useful civilian systems, despite the fact that civilian flights would look an awful lot like weapons. And if you're moving at Mach 17, it's not like adversaries have very long to decide how to react.

          Anyhow, existing ICBM systems are quite a bit faster than this — Minuteman III tops out at Mach 23 and Trident II at Mach 24.

          • I honestly don't get why the military keeps working on new hypersonic missiles when WE ALREADY HAVE HYPERSONIC MISSILES and have had for the last 50 years. It's not like our adversaries are going to look at this and say "well, ICBMs were bad and scary but these new launchers are fine because they're airbreathing, we sure won't resume our arms race for those."

            I can think of several offhand:

            • - They travel at a much lower altitude than ICBM's. reducing radar warning time.
            • - Since they're not surrounded by re-entry plasma, they could conceivably mount sensors of varying kinds to improve accuracy.
            • - It's quite likely (since they're not limited to ballistic trajectories) they'll be able to take evasive action and maneuver on deceptive flight paths.

          • I honestly don't get why the military keeps working on new hypersonic missiles when WE ALREADY HAVE HYPERSONIC MISSILES and have had for the last 50 years.

            There's a big difference between weapons that achieve hypersonic speeds via a big rocket booster, and AIR BREATHING hypersonic weapons. In rocket fuel and explosives alike only about 25-33% of the mix is fuel - the rest is oxidizer. Thus, anything that breathes air - that gets its 02 for "free" from the atmosphere - is MUCH lighter and smaller than a ballistic rocket booster. This matters a lot when you're trying to load missiles onto, say, a warship, with strict tonnage and volume limits. Or an aircraft, f

        • Mach 17 is around the equator in two hours.
          You are roughly 1 hour off :P

          • Re: (Score:3)

            by suutar ( 1860506 )

            to clarify (assuming I understand your point) while earth is 25000 miles around and going that far at mach 17 would be about 2 hours, you would not in fact go all the way around to hit something close. Therefore no point is actually further than 1 hour away.

            • Unless there is a good reason to not take a certain route. E.g. flying over Russia or China. But the < 1h distance is actually a good point. I wonder how quick such a plane would accelerate and ow it decelerates again. Talking about a plane, not a missile ...

      • Re: (Score:2)

        by alxc ( 853960 )
        " Also there's really a question if there's any practical benefit to a missile that goes Mach 17 over Mach 10." My Mach is faster than your Mach.

      • I sincerely doubt this has any practical benefit in weapons.

        Depending on how small the engine could be made, having a missile capable of Mach 17 means the time to target is insignificant on the battlefield. If you have a jet five miles away and it's called in to take out a tank or artillery battery, the people on the ground will literally, in the truest sense of the word, not have time to react before they're turned into pink mist.

        Another option would be put these into ICBMs. The first stage is conventio

        • I sincerely doubt this has any practical benefit in weapons.

          Depending on how small the engine could be made, having a missile capable of Mach 17 means the time to target is insignificant on the battlefield. If you have a jet five miles away and it's called in to take out a tank or artillery battery, the people on the ground will literally, in the truest sense of the word, not have time to react before they're turned into pink mist.

          Another option would be put these into ICBMs. The first stage is conventional to get it out of the silo/out of the missile tube, then this engine kicks in. As someone else said, the target could track the incoming missile and throw up a bunch of stuff to try and hit the missile, but your aim would have to be dead on or at least close enough to deflect it. Which would then send a wave of debris at you any way. Depending on how close to the target the incoming was destroyed, kinetic energy of the pieces could still do damage. Especially to soft targets like humans.

          I would think a cluster of Lazy Dogs [wikipedia.org] going alongside the main payload raining down at Mach 17 would be a nasty thing.

      • Also there's really a question if there's any practical benefit to a missile that goes Mach 17 over Mach 10.

        There is a clear benefit of 7.

      • Re: (Score:2)

        by necro81 ( 917438 )

        Also there's really a question if there's any practical benefit to a missile that goes Mach 17 over Mach 10

        As the article points out: at those speeds you don't really even need a warhead, the missile is a kinetic weapon. As such, going from Mach 10 to Mach 17 almost triples the kinetic energy (1.7 * 1.7 = 2.89). So, yes, there's probably a benefit there.

      • any practical benefit to a missile that goes Mach 17 over Mach 10.

        You use the Mach 17 missile to shoot down the Mach 10 one.

        If at those speeds the interceptor's detonation can be timed accurately enough to be sufficiently close to do any damage.

      • Re: (Score:2)

        by PPH ( 736903 )

        if there's any practical benefit

        Bragging rights. It's the Pentagon's version of "our missiles go to eleven."

      • A Mach 17 missile is a hell of a lot better at intercepting a Mach 10 missile than another Mach 10 missile is.

    • Re: (Score:2)

      by hey! ( 33014 )

      It's a big deal because other countries are doing it.

    • I feel there have been variations of "hyper super duper fast airplane engine" for decades with nothing more to show than scale models in Oscar Goldman's office.

      https://en.wikipedia.org/wiki/... [wikipedia.org]

  • You can see harmonics affecting the propulsion jet angle. I imagine a super sonic wavefront would induce harmonic effects across the device including the nozzles and especially the explosion chamber. How would you even tune a fuel nozzle when the pressure changes every time you retune it? I suppose that’s what they mean by complicated dynamics.

  • ...or that it breaks apart after three seconds!

  • Passenger application? (Score:3)

    by Monty Worm ( 7264 ) on Friday May 14, 2021 @03:41AM (#61383364) Journal
    Can we get this in a passenger aircraft?

    It'd cut other-side-of-the-world trip journey times from 24 hours (approx) down substantially.
    My quick calculation suggests approx time to orbit at the equator is about 2 hours at M17, but you couldn't run that as an average speed, plus getting airborne, into airspace where sonic booms won't disrupt third parties but should be able to come down to 5-6 hours, say London -> Sydney over the North Pole and down the dateline.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      Might be difficult... At that speed the amount of heating of the cabin would be a problem for the occupants. The noise level might be too, if you prefer not to go deaf.

    • My quick calculation suggests approx time to orbit at the equator is about 2 hours at M17

      The problem with passengers is they take up space that could otherwise be filled with fuel. At those speeds, air resistance will be insanely high and you will burn fuel at a huge rate to maintain it so it is likely that a passenger jet would have a very low range making it somewhat less useful and insane fuel costs making it very expensive. Then there is the noise issue. Concorde was restricted to trans-oceanic flights only because of the sonic boom.

      So while a passenger jat that can get anywhere in the

  • The description of difficulty in tuning so the shockwave does not back up the fuel line exploding it means it is I guess for missiles and crazy attack drones. Could a human even handle it? Might be nice to have some of these for missile defense..

  • So they've got the engine sorted (Score:5, Insightful)

    by Viol8 ( 599362 ) on Friday May 14, 2021 @05:46AM (#61383494) Homepage

    But what do they plan on building the fuselage out of that can survive doing 13K mph in atmosphere for any prolonged period of time?

    • The only flight regime where this could be used is at extremely high altitude where the air is very, very thin since the drag and heating at this speed is extreme. The only vehicles that encounter such conditions now are re-entry bodies that are shedding velocity rapidly due to that high drag and expecting only very short exposures to those high temperatures.

      So this could have an application in a reusable launch system where this is helping to get close to where rockets must be used but with an air breathin

  • Sustained detonation vs conventional burning (Score:4, Interesting)

    by JoeRobe ( 207552 ) on Friday May 14, 2021 @05:50AM (#61383506) Homepage

    I wasn't quite understanding this from the article: what is the difference between a sustained detonation and the more conventional fuel burning? Are the same bonds broken/products formed?

    I guess I'm wondering what metrics you'd look at in their experiment to determine whether that its co to you a detonation.

    Not that I'm questioning their results, just trying to understand them.

    • Re: Sustained detonation vs conventional burning (Score:5, Informative)

      by Åke Malmgren ( 3402337 ) on Friday May 14, 2021 @07:48AM (#61383686)
      In burning, heat from the fire sustains the reaction. In a detonation, heat from pure compression does the same job, but a lot quicker. There's also some thermodynamic reason I don't fully understand (possibly higher peak pressure?) which makes more of the energy in a detonation able to perform work.

    • If you've ever driven a classic car, one so old that it doesn't tune itself up, you may have heard it "knocking". That's the difference between detonation and deflagration. Instead of a steady push on the piston there's a bang.

      I don't know what you measure in the lab to make the distinction.

    • Re:Sustained detonation vs conventional burning (Score:4, Informative)

      by Solandri ( 704621 ) on Friday May 14, 2021 @11:57AM (#61384542)
      Scott Manley has a good video [youtu.be] describing how these work and the potential advantages (the video is on rotating detonation engines, but the physics of the detonation are the same for pulse and oblique wave detonation engines). It's a simpler design. There are no moving parts - no mechanical compressor needed for the engine. The detonation wave itself creates the compression. And the pressures you can achieve are much higher than mechanical compression anyway. The resulting thermodynamic cycle has a broader hysteresis, meaning you can extract more mechanical energy from the combustion. And the potential impulse is higher - you can get to higher speeds/go further with the same mass of propellant.

  • On to the next problem (Score:3, Insightful)

    by prisoner-of-enigma ( 535770 ) on Friday May 14, 2021 @06:05AM (#61383516) Homepage

    Great, we have an engine that can push an aircraft to Mach 17. Now all we need is an aircraft that can survive the continuous aerodynamic heating at Mach 17. That problem alone is at least as challenging as coming up with the engine.

  • the Pulse Detonation engine used (supposedly) by the Aurora reconnaissance aircraft.

  • To put this in perspective, mach 17 is 13,043 MPH. The ISS orbital velocity is 17,130 MPH. So we're talking about speeds in the realm of astronomical / orbital re-entry velocity here. As we all know, it takes a tremendous amount of heat shielding to survive travelling through the atmosphere at those kinds of speeds (and even then, it is extremely high in the atmosphere where there is much less air).

    The reason spacecraft do not need heat shields on launch is because they are not reaching those kinds of ve

  • Hey air- and space-craft guys, teach me. One hears about the Chinese rocket burning up on re-entry. What would it be like flying through our atmosphere at Mach 17? Would we require extra- or special-cladding? Extra weight and all that? What are all the real-world requirements to make this reasonable for human flight, or are we just going to be doing drones with this? Of course, TL;DR. Thanks!

    • You're right - materials research is a huge part of hypersonics. Stagnation temperatures above Mach 3 and 4, let alone Mach 17, get quite toasty, and you can only put so much ablative coating on a vehicle. The weight tends to be a much lower concern than the temperatures.

  • However anything going Mach 17 is going to quickly get white-hot and quickly run out of fuel, so applications are going to be quite limited.

    • The space shuttle glowed for 10 minutes during re-entry, suppose a craft could somehow manage heat for that long. that's a 2200 mile / 3500 km journey.

  • Really? And what are they going to use to cool the rest of the vehicle? At mach 17, friction heating with the atmosphere approaches an incoming Shuttle.

  • Noting that the (or a) Pulsejet [wikipedia.org] engine was first patented in 1867.

    Russian inventor and retired artillery officer Nikolaj Afanasievich Teleshov patented a steam pulsejet engine in 1867 while Swedish inventor Martin Wiberg also has a claim to having invented the first pulsejet, in Sweden, but details are unclear.

    The first working pulsejet was patented in 1906 by Russian engineer V.V. Karavodin, who completed a working model in 1907. The French inventor Georges Marconnet patented his valveless pulsejet engine in 1908, and Ramon Casanova, in Ripoll, Spain patented a pulsejet in Barcelona in 1917, having constructed one beginning in 1913. Robert Goddard invented a pulsejet engine in 1931, and demonstrated it on a jet-propelled bicycle. Engineer Paul Schmidt pioneered a more efficient design based on modification of the intake valves (or flaps), earning him government support from the German Air Ministry in 1933.

  • There's a high-efficiency one-moving-part internal combustion engine under development (at Michigan State University, I think) that uses a triggered detonation wave in a rotor that serves as both the compressor and turbine, along with a shaped housing that, by opening and closing the passages in the rotor, keeps the wave where it should be.

    If the passage could be shaped to hold a continuous detonation wave in place it would get 'way simpler.

    (Detonation waves are good for efficiency in an I.C. engine desined

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