Even if you ignore that, it ended very strangely. Feels like there was more to it, but he cut something out during editing and didn't record a new ending.
If you think thermo is kind of alright I strongly recommend going the career way of technical safety engineering. It's a load of fun dealing with fires and explosions all day
I helped build the first self-aspirating Pulsed Detonation Engine with Dr. Fred Schauer at Air Force Research Laboratory in 2003. It was built with junkyard parts (An old Honda motorcycle engine with the tubes jutting out between the block and head), but proved the concept. They made another non-self-aspirating PDE (it had a supercharger powered with a piston engine) that actually powered a Long-EZ in flight several years I left the program, which is the one you see at 3:50 in the video. You're just seeing the PDE there- the big compressor in the belly tank that fed it. I still have my engineering-pad sketches of a variety of rotating PDEs, except my ideas would have one wall of the tube rotate, or have the tubes rotate more like a gatling gun.
@yeah I'm John Assal No actually these PDEs used a kind of simple metal helix inside the tube to initiate detonation. The idea was to not use mere automative valves.
blurglide interesting! I imagine either an annular tube with a spinning core, annular tube with a rotating outer sleeve, or a Gatlin exhaust with the tubes each ‘’firing’’ as they read top dead center. I don’t understand enough, but I imagine a series of vanes synchronizing with my first two imaginings, and the Gatlin seems fairly straightforward. I’m probably wrong as all hell. I have no training in physics, but I do like to draw! This’ll be fun! Y’all take care.
The thermodynamics of the detonation engine compared to standard rocket engines is very much like the new HCCI (Homogeneous Charge Compression Ignition) engines compared to standard petrol engines. HCCI engines have been developed which compress the air fuel mixture to just below spontaneous combustion. The spark plug then ignites the fuel air mixture and the slight pressure increase from deflagration causes detonation of the rest of the air fuel mixture. The pulsed detonation engine is basically an HCCI engine without the pistons and vice versa from what I can see. The rotating detonation engine looks like a very interesting concept, just need some way to stabilise the detonation wave. Maybe with a rotating inner or outer sleeve as you mentioned, with a shaped portion on the sleeve which moves with, and helps control, the detonation front.
@Daniel Downs Yeah you have the basic idea there. There's already a sort of helix (kind of like rifiling, but held a short distance off the wall). You could have the nozzles angled to provide the rotation, and put the entire thing in a duct for better subsonic efficiency and for cooling (these tubes glow red hot at their bases). For slower things, we were even thinking PDEs could replace the combuster in regular jet engines, giving you a lot of extra compression for free and deadening the noise. Oh yeah- these prototypes were LOUD. Like a machine gun, but WAY louder.
We managed to film transfer from deflagration to detonation in oxy-acetylene mixture last year with some serious high speed camera setup. Many viewers said that we almost made science by accident since it was so interesting shot :D Here is link to slow motion clip of that ua-cam.com/video/p9XandILnvk/v-deo.html Edit: I already forgot but seems that we also filmed rotating explosion with oxy-acetylene bubbles :D Just one lap but still. It's on end of the same video
• RDE’s need a single initiation for operation and the combustion is self-sustained. The detonation waves will stabilize in a short duration. • Frequency of operation is of the order of KHz. Which makes uniform exhaust flow downstream of the combustor. • Compared to PDE’s the thrust produced by an RDE is continuous. The detonation waves are enclosed inside the channel which reduces the energy lose with exhaust. Which makes it a suitable replacement for the gas turbine combustor. • The reactant inflow does not require any flapping valves as well as it is a self-pressurizing system. The injection pressure loss will be overcome by pressure gain combustion. So it is easy to integrate it with an axial compressor with lesser number of stages. • RDE’s have very high power density, so that the size of the combustor reduces drastically. • Smaller the size of the combustor, smaller will be the losses due to wall heat transfer. Moreover, the exhaust flow can be simply approximated to a 1D quasi steady flow. • It is easy to resize the combustor because there isn’t any hard rule for the size constraints. • Fuel injection system associated with such combustors are fairly simple, as they don’t need any moving parts or swirlers. • Integration with an existing turbine stage will be easy because of lower unsteady pressure fluctuations downstream of a properly designed RDE combustor. • Propagation of the detonation wave independent of direction of inflow and outflow of reactants and products respectively. Such combustor can be easily integrated to axial as well as centrifugal compressors. • Even though there is no need of a secondary air for dilution of exhaust, if employed it will further reduce the periodic oscillations downstream of the combustor. • RDE’s possess large effective thrust, which is a measure of how well the total pressure of reactants are converted to thrust. So an engine employed with RDE combustor can work with lesser number of compressor stages compared to the same system with a constant pressure combustors. • Large specific thrust and high Specific impulse of the system make sure the maximum utilization of the available air. • Operating space (mass flow rate of reactants vs equivalence ratio) is wide for an RDE combustor. So it can be effectively operated with equivalence ratios required for low emissions. • Most preferable reactants which can be initiated are H2 and O2 combination. So having a clean combustion is favored with such combustors. • The mode control is not well defined as of now and there are scope of having multiple co rotating detonation propagation can improve the capabilities of this combustor.
So, in addition to increased efficiency and many other benefits, it sounds like RDE's should be lighter and more compact. Does that mean RDE's also promise better thrust-to-weight ratio?
@@DistracticusPrime Too soon to tell about "lighter and more compact", surely, since we don't have a practical working design and don't know yet what additional hardware/reinforcement/plumbing will be added to make one. But even if they're heavier and *less* compact than current engines, the improved efficiency will, at some particular breakpoint, make up for that. And then we'll be in for lots of interesting new discussions about optimal vehicle design. =:o}
It's not easy to find conditions, where the waves stabilize. I'm not really informed on that subject, as I had a brief contact with it in 2014, while doing my internship, yet I remember the problems. It was extremely difficult to find conditions, where the waves were created in a repeatable pattern - sometimes it was just one, sometimes two, or even three. And then, the biggest problem at that point of the project, was the transition from H2 to jet fuel. It was a real bummer for the team, when the engine flamed out just after couple of seconds or sometimes the exhaust gas temperature rose above the critical for the turbine, which meant that they had to switch it off and the whole procedure had to be repeated. It was called a success, when they managed to get 25s of continous work. I only wish, I kept in touch with the team, to track their progress. I only hope, that some team from around the world will finally manage to keep it all steady and reliable, as the idea of RDE always seemed great for me.
As a PhD student researching combustion and detonation processes, I’m very impressed by how intuitively you explained the differences between the two. Great video!
@@thefreemonk6938get out there and involve yourself. Hard to get into it from 0 but start talking to people, show interest in their interest. People love sharing their interests. Surround yourself with people who are doing these things, this is to start. It’s who you know.
You videos strike a perfect balance between hardcore science and a pop sci. It's super hard to explain such complex topics without degrading into totally handwavy talks. And it involves very good understanding of the subject. I can't even imagine how much researching do you put in. UA-cam is a better place thanks to you! Thank you :)
Scott, take a look at work of Jan Kindracki from Warsaw University of Technology, Poland. This guy is was recently taking care of applying a RD into an old Russian turbine engine (GTD-350) to prove a concept. Jan is great teacher (during our studies we had some lectures about RDE to better understand it) and he's really responsive. As far as I remember he was able to sustain a detonation in a relatively small rocket engine (100-200N?) for 10+ seconds if I remember correctly. Awesome dude and his lab even better. Don't quote me on numbers - it was years ago.
Lacking a requirement to fly safe, the Insane American flew very deadly. **Dual Vulcan sound* **GAU-8 sound* **GBU-16 sound* **AGM-65 sound* **Various explosions* Damage: about $1200000, 12 wounded.
@@user2C47 Many years ago my parents took me to an air show. I stood on the roof of our car (in those days cars were built of thicker steel) and clutching my camera awaited the Vulcan flyby. This is hard to put into words but maybe "awesome", "bonkers" and other adjectives will apply. As the Vulcan flew low overhead I nearly fell off the roof of the car, everything shook! I got the the shot but the Vulcan looked quite small, it was only a basic camera. I can never forget that!
As a life long fan of space flight (watched first moon landing when I was 5), I have been slowly learning the technical aspects of rockets. My dad was a race engine builder. One of the things that allows a auto engine to work is that it cycles the most heat stresses parts. Getting a little time to cool makes the metals used able to deliver amazing performance. Sounds like it's time to apply the same idea to rocket engines.
Possibly - one of the things to understand about rockets is that they are: 1- not 'mass-produced' and therefore more given to using exotic materials than most engine blocks 2- focus more on constant thermodynamics and on thermal stress tolerances than 'duty cycles', whether milliseconds or minutes long; one of these ideas is found in nozzle designs, specifically in ablative vs. rigid, and the innovation of _regenerative cooling._ Dealing with detonations would require more of the engineering involved in harmonic balancing for driveshafts - dampeming/destroying vibrations & such. If you haven't already, look up Scott's video on designing and testing the F-1 engine for the Saturn V.
@@HuntingTarg In response to point 1: It is the exhaust valves that are the most thermally and structurally stressed part in a 4-stroke piston engine. Modern race engines routinely make use of exotic alloys for the valve & seat. The amazing performance would not be possible without the time for cooling while closed. In response to point 2: I have been well aware of the basic technical features of our current state of the art in rocket engines since I was in my twenties when the space shuttle was in development. What I am trying to say is that intermittent combustion based on the detonation cycle (while fully aware of how hard it will be to work out the harmonic stresses) would allow us to leverage the use of the best materials even more than they are now. A 25% efficiency improvement is a BIG chunk of mass in fuel. Engines could be a lot heavier and still come out ahead.
@@markhatch1267 👍 We're roughly the same age and came into real-life rocketry through the same avenue - the Orbiter program. I'm aware of the thermomechanical stresses on valve covers, and while you're quite right, 90+% of any production-line engine block is some variety of hardened steel or cast aluminum - economies of scale don't like high-tolerance, expensive parts. (I said 'more given to', since the quantities rocket motors are made in lines up with Supercars).
@@markhatch1267 I have a notion, that in a rocket engine that is typically designed for radially aymmetrical collimvariable flow, a 'rotating detonation' within the combustion chamber could introduce undesirable flow instabilities. While this may or may mot be a problem, I have to wonder what a rocket motor designed for vortical flow would be like - and _then_ wonder what detonation front would be like in _that_ engine... 🤷♂️💡
Scott, you are so freaking concise....that was a GREAT video, amongst many of ur best. ....of which, you have many. Thx for all your hard work educating us laymen, to help us grapple these insanely intelligent concepts from other, alien-level-smart, humans. Kudos, happy new year!
If Colin Furze sees this video, you just know that he's going to find pulsed detonation _way_ cooler than pulsed deflagration and he's going to build one. And do something ridiculous with it.
Fantastic video, you explained this thoroughly and clearly. Im a Mechanical engineering major and you refreshed some of my thermo concepts while explaining something new. Thank you so much for putting this together!
One useful consequence of airbreathing RDEs possible not needing a compressor is that they then do not need a turbine either, as the sole purpose of the turbine is driving the compressor. This means you can run it much hotter, as you don't need to worry about the turbine blades melting.
If the tube is the right size you could tune the sound. Like a Harley. What you would hear is the vibration caused by the resonance frequency of the tube which would change as the flame front moves down the tube, Like a slide whistle.
They tested that (3:50) PDE at 5 am on a Saturday, a mile away from my apartment in Mojave. This woke me, terrified my cats, and pissed me off. It cut off after a few seconds, and a minute or three later did another burst. And again... the effect was like having a machine gun going off outside my window. Long story short, they were confronted by a wild man wearing two layers of hearing protection who threw a total screaming obscenity-laden fit at them. Further static tests were done in the day time at the far side of the airport from the town.
Thank you for another awesome video! After I saw some articles about this I have been patiently waiting for your video so I can actually understand it.
This is a great introduction to RDTs. I am impressed with how you encapsulated the challenge of modeling this theoretically, especially with regard to the development of multiple detonation fronts.
A friend is actually working on this at Argonne, totally were brainstorming this topic a couple summers back in a nearby Starbucks haha! Totally gonna show him your video Scott
Thanks Scott for your usual enlightening explanation for plebs like me. This looks like a real step up in efficiency so I am sure buckets of money are being thrown at it. Everytime I see video of that prototype I think of Firefly, or back even further the original Jupiter II. :) Who knew Irwin Allen was a physics visionary?
Months ago I thought of an engine design with only one moving part, it has the core principles of functioning the way a Wankel Engine works, but doesn't have an odd circular path, the center part stays fixed in place while spinning, no shims to wear out, and it doesn't need oil, just grease for two bearings, Centrifugal forces bring in new fuel and air, also exhausting burnt fuel. This engine is also perfect for using HHO
At 4:55, the long red tube is the igniter, starting with a deflagration that becomes a detonation, and launching that into the chamber. The main propellant feed is through the small axial tubes, at right angles to the travel of the detonation wave. The feed is subsonically supplying the blue cool mix, which the shock travels through at mach 2 to 5 or so. Note that at 5:19 the two shocks coalesce into one stronger shock after a few revolutions, a tiny fraction of a second in real time. As long as the chamber is not too short, the feed mix can't escape without getting shocked and burned as the wave comes around.
the physics is closely related to Tuned Headers on classic V8 engines... where cam timing is generally critical. JFF, BMW "airhead" motorcycles use strategically-located "balancer tubes" on their exhaust systems.... exhaust pipe length... even muffler-end shape... is also very important... to enhance exhaust system "scavenging".... on the aforementioned V8 engines, 4" pipes, vs. 3" exhaust systems can be catastrophically counter-productive (particularly at high RPM)... the same physics has also been applied to tuned intake manifolds - similarly, with commensurate cam/ignition timing (consider the physics of cold gases, vs. hot gases... along with atmospheric Nitrogen/oxygen dynamics). There have also been experiments with "acoustic turbo-chargers" for internal combustion engines. Ask any competent mechanic about the relationship of ignition timing vs. flame front (TDC, BTDC, ATDC)
Very nice to have some heat engine thermodynamic cycles explained by charts. It is difficult to go into efficiency calculations without covering a lot of background material but pointing out that work corresponds to the enclosed area in P-V diagram as you did gives a very good idea of what is involved in increasing efficiency.
Pretty much every rocket engine I have ever made was technically a non-rotating detonation engine. Or an enhanced deflagration engine, depending on how fast they disassembled themselves
@@scottmanley How Long Do You Think Realistically It Will Be Scott Before We See These Rotating Detonation Engines AND Aerospike Engines Used In New Launch Vehicles And Spacecraft ? ? ?
Made think... Was the V1 sort of utilizing detonation? On the other hand, you do your most to avoid detonation mode in your car engine cylinders. Seek service, if you hear a certain kind of knocking.
Sick video. I'm doing my PhD at Embry-Riddle and a few times a year I have to give tours of the Gas Turbine Lab.. there's a pulse detonation experiment that's just been sitting there for a few years with no grad student working on it and folks always ask lots of questions about it.. it has nothing to do with my research so I've been saying "I don't know" a lot. Now I can just brush up with this! Life hack
This is the Scott Manley I like. 1. Tells me something I didn't know before the video 2. Just technical enough to wet my engineer and mathematical whistle 3. The subject is interesting 4. Scott Manley isn't in a bath-robe
0:42 Bambi P.S. Excellent description of detonation vs deflagration. Detonation is when the reaction front moves faster than the local speed of sound, creating shock wave(s) and much higher resultant pressures.
I just read an article about hypersonic missiles and this video was attached. I want to let you know how helpful this explanation was. Thank you very much for this video. I have a small background in science, so this was a perfect introduction to the concept.
This constant volume heat delivery reminds me of the Otto cycle, which, for a given compression ratio, has higher efficiency than the Diesel cycle. Funny enough, you can't increase the compression ratio in an Otto engine too much because of, well... detonation :-)
Many of the problems of preignition and detonation have been solved with the HCCI Homogeneous Charge Compression Ignition. The charge is ignited by either injecting a easu to ignite liquid such as DME (Dimethy Ether) or manipulation of the air fuel ratio and exhaust gas re-circulation. The RCCI engine Reactivity Controlled Compression adds a spark plug. Daimler Benz was testing them in WW2 all the way to 40,000ft. Formula 1 use them and they are 45%-50% efficient. It's likely they will operate to 58% efficiency. Better than fuel cells.
I'm a simple man, a farmer and yet this stuff absolutely amazes me...... I'll be in my shop later messing with fire and telling my son to "hold my beer, watch this" and later tonight we'll be sitting in the ER and my wife will be saying "WTF were you thinking" ...... Thanks for posting another fun video, let's see what we can build now🎉
Excellent. I read about the Japanese actually flying one of these today, and so I wanted to learn more about it. I should’ve known you’d have an old video about it! This is so cool
Experiment: 12" "woofer" placed "face-down" on a smooth surface; apply swept sine wave signal from audio amplifier; how much power can be applied to momentarily lift ( through air pressure)the woofer off of the surface... at what frequency would the speaker remain suspended, where it's momentary inertia would "hold' it in place, before it begins to fall back? try connecting a tuned tube to the back of the speaker... potentially off-setting the nodal/antinodal points. (bass-reflex speakers can stimulate an in-phase resonance... with up to 3dB gain @ Fs/ Fso)... placing speaker "face up" on a scale (to measure force in grams) could lead to further insight(s)... just for fun, add a second woofer to the other end of the tube and experiment with phase alignment... nodal at the bottom, antinodal at the top...
He didnt tell me thats he's scott manley and to fly safe at the end.
I feel lost.
he DID say hes scott manley. its literally the first thing he says
Maybe he just did not think it would be necessary since nobody is actually flying these days... \__/
oops!
I screwed up the edit!
It was so jarring. I though I had accidentally pressed against my phone, causing it to skip forward.
I have flown ... unsafe..
"I don't have any rocket engines in my garden"
- totally what someone with rocket engines in their garden would say.
ikr
TAndrei Kucharavy HaHa I would love to have a rocket engine in my garden !!
I was expecting Scott to add to the end of that statement: *"...YET."*
😊😊😊
As of today, i can confirm that i do have a rocket engine in my garden!
@@robbiejames1540 After testing: You have a rocket engine in what was your garden.
Now i am wondering if i have to fly safe or not....
this world is full of uncertainties....
It's not safe to flay these days.
When you have something called "rotating detonation engine", you can't fly safe.
If you can't Fly Safe.....Fly dangerous!
Even if you ignore that, it ended very strangely. Feels like there was more to it, but he cut something out during editing and didn't record a new ending.
@@Phelan666 I'm not sure flaying is ever safe... ;p
At least, not for the person being flayed. XD
You know, it's kind of funny: I'm taking a break from my thermo class to watch this video, and this video is half ideal heat engines!
@MillionFoul I just had my final on the 2nd, gotta love those P-V diagrams.
Has our first midterm on the 9th and will have our final on the 19th. Midterm was a disaster for everyone haha
If you think thermo is kind of alright I strongly recommend going the career way of technical safety engineering. It's a load of fun dealing with fires and explosions all day
You're gonna learn dammit!
I failed my thermo exam😔😔
I helped build the first self-aspirating Pulsed Detonation Engine with Dr. Fred Schauer at Air Force Research Laboratory in 2003. It was built with junkyard parts (An old Honda motorcycle engine with the tubes jutting out between the block and head), but proved the concept. They made another non-self-aspirating PDE (it had a supercharger powered with a piston engine) that actually powered a Long-EZ in flight several years I left the program, which is the one you see at 3:50 in the video. You're just seeing the PDE there- the big compressor in the belly tank that fed it. I still have my engineering-pad sketches of a variety of rotating PDEs, except my ideas would have one wall of the tube rotate, or have the tubes rotate more like a gatling gun.
@yeah I'm John Assal No actually these PDEs used a kind of simple metal helix inside the tube to initiate detonation. The idea was to not use mere automative valves.
blurglide interesting! I imagine either an annular tube with a spinning core, annular tube with a rotating outer sleeve, or a Gatlin exhaust with the tubes each ‘’firing’’ as they read top dead center. I don’t understand enough, but I imagine a series of vanes synchronizing with my first two imaginings, and the Gatlin seems fairly straightforward. I’m probably wrong as all hell. I have no training in physics, but I do like to draw! This’ll be fun! Y’all take care.
Can I get one of those for my Hyundai? That's a badass engine.
The thermodynamics of the detonation engine compared to standard rocket engines is very much like the new HCCI (Homogeneous Charge Compression Ignition) engines compared to standard petrol engines. HCCI engines have been developed which compress the air fuel mixture to just below spontaneous combustion. The spark plug then ignites the fuel air mixture and the slight pressure increase from deflagration causes detonation of the rest of the air fuel mixture. The pulsed detonation engine is basically an HCCI engine without the pistons and vice versa from what I can see. The rotating detonation engine looks like a very interesting concept, just need some way to stabilise the detonation wave. Maybe with a rotating inner or outer sleeve as you mentioned, with a shaped portion on the sleeve which moves with, and helps control, the detonation front.
@Daniel Downs Yeah you have the basic idea there. There's already a sort of helix (kind of like rifiling, but held a short distance off the wall). You could have the nozzles angled to provide the rotation, and put the entire thing in a duct for better subsonic efficiency and for cooling (these tubes glow red hot at their bases). For slower things, we were even thinking PDEs could replace the combuster in regular jet engines, giving you a lot of extra compression for free and deadening the noise. Oh yeah- these prototypes were LOUD. Like a machine gun, but WAY louder.
We managed to film transfer from deflagration to detonation in oxy-acetylene mixture last year with some serious high speed camera setup. Many viewers said that we almost made science by accident since it was so interesting shot :D Here is link to slow motion clip of that ua-cam.com/video/p9XandILnvk/v-deo.html
Edit: I already forgot but seems that we also filmed rotating explosion with oxy-acetylene bubbles :D Just one lap but still. It's on end of the same video
So awesome! Thank you!
Imagine using the slomo ring to film a rotating detonation engine and synchronize the flame to the ring's rotation!
HI LAURIE AND ANNIE
Whoa Laurie and Anni watch Scott Manley? Sweet
It could really be interesting to offer the Ring for these research labs. :D
It feels weird that you don’t wish us fly safe at the end of the video
yeah , it was like - good night....
It's a tragedy, I messed up the edit
Chico Liu
Doesn’t Scot want us to fly safe anymore?
Has the recklessness of some Americans got to him?
@@scottmanley it's one step closer to the end of the world
@@scottmanley
That's OK, I had this engine in a question the other day, and here it is!
• RDE’s need a single initiation for operation and the combustion is self-sustained. The detonation waves will stabilize in a short duration.
• Frequency of operation is of the order of KHz. Which makes uniform exhaust flow downstream of the combustor.
• Compared to PDE’s the thrust produced by an RDE is continuous. The detonation waves are enclosed inside the channel which reduces the energy lose with exhaust. Which makes it a suitable replacement for the gas turbine combustor.
• The reactant inflow does not require any flapping valves as well as it is a self-pressurizing system. The injection pressure loss will be overcome by pressure gain combustion. So it is easy to integrate it with an axial compressor with lesser number of stages.
• RDE’s have very high power density, so that the size of the combustor reduces drastically.
• Smaller the size of the combustor, smaller will be the losses due to wall heat transfer. Moreover, the exhaust flow can be simply approximated to a 1D quasi steady flow.
• It is easy to resize the combustor because there isn’t any hard rule for the size constraints.
• Fuel injection system associated with such combustors are fairly simple, as they don’t need any moving parts or swirlers.
• Integration with an existing turbine stage will be easy because of lower unsteady pressure fluctuations downstream of a properly designed RDE combustor.
• Propagation of the detonation wave independent of direction of inflow and outflow of reactants and products respectively. Such combustor can be easily integrated to axial as well as centrifugal compressors.
• Even though there is no need of a secondary air for dilution of exhaust, if employed it will further reduce the periodic oscillations downstream of the combustor.
• RDE’s possess large effective thrust, which is a measure of how well the total pressure of reactants are converted to thrust. So an engine employed with RDE combustor can work with lesser number of compressor stages compared to the same system with a constant pressure combustors.
• Large specific thrust and high Specific impulse of the system make sure the maximum utilization of the available air.
• Operating space (mass flow rate of reactants vs equivalence ratio) is wide for an RDE combustor. So it can be effectively operated with equivalence ratios required for low emissions.
• Most preferable reactants which can be initiated are H2 and O2 combination. So having a clean combustion is favored with such combustors.
• The mode control is not well defined as of now and there are scope of having multiple co rotating detonation propagation can improve the capabilities of this combustor.
So, in addition to increased efficiency and many other benefits, it sounds like RDE's should be lighter and more compact. Does that mean RDE's also promise better thrust-to-weight ratio?
How throttlable is it? Can we land rockets with it?
Time to practical application?
@@DistracticusPrime Too soon to tell about "lighter and more compact", surely, since we don't have a practical working design and don't know yet what additional hardware/reinforcement/plumbing will be added to make one. But even if they're heavier and *less* compact than current engines, the improved efficiency will, at some particular breakpoint, make up for that. And then we'll be in for lots of interesting new discussions about optimal vehicle design. =:o}
It's not easy to find conditions, where the waves stabilize. I'm not really informed on that subject, as I had a brief contact with it in 2014, while doing my internship, yet I remember the problems. It was extremely difficult to find conditions, where the waves were created in a repeatable pattern - sometimes it was just one, sometimes two, or even three. And then, the biggest problem at that point of the project, was the transition from H2 to jet fuel. It was a real bummer for the team, when the engine flamed out just after couple of seconds or sometimes the exhaust gas temperature rose above the critical for the turbine, which meant that they had to switch it off and the whole procedure had to be repeated. It was called a success, when they managed to get 25s of continous work.
I only wish, I kept in touch with the team, to track their progress. I only hope, that some team from around the world will finally manage to keep it all steady and reliable, as the idea of RDE always seemed great for me.
As a PhD student researching combustion and detonation processes, I’m very impressed by how intuitively you explained the differences between the two. Great video!
it seems like combustion to me, too, but specifically at "supersonic" speeds.
How to become like you?
@@thefreemonk6938get out there and involve yourself.
Hard to get into it from 0 but start talking to people, show interest in their interest. People love sharing their interests. Surround yourself with people who are doing these things, this is to start. It’s who you know.
"Anyways, I'm Scott Manley! FLY SAFE!"
WE MISSED YOUR OUTRO! 😕
Spencer Coleman Ain’t nobody flying and Scott knows this!
Shibboleth
i think... he just gave us permission to fly dangerously.
I was gonna say it for him! glad somebody already did! :)
Pavlov no ringy bell.
You videos strike a perfect balance between hardcore science and a pop sci. It's super hard to explain such complex topics without degrading into totally handwavy talks. And it involves very good understanding of the subject. I can't even imagine how much researching do you put in.
UA-cam is a better place thanks to you! Thank you :)
4:14
You do realise you've just challenged Colin Furze to build a supersonic pulsed-detonation engine....
(this is gonna be awesome)
Scott, take a look at work of Jan Kindracki from Warsaw University of Technology, Poland. This guy is was recently taking care of applying a RD into an old Russian turbine engine (GTD-350) to prove a concept. Jan is great teacher (during our studies we had some lectures about RDE to better understand it) and he's really responsive. As far as I remember he was able to sustain a detonation in a relatively small rocket engine (100-200N?) for 10+ seconds if I remember correctly. Awesome dude and his lab even better. Don't quote me on numbers - it was years ago.
I've got a flight to catch in the morning and I feel very nervous after the end of this video...
Fly safe!
@@jannegrey Thank you, I feel better.
Don't worry, most deaths associated with aircraft accidents are near instantaneous so if you do die it will likely be painless
@Anant Tiwari Yes, the engine detonated but I figured it was a new development in the aviation world so I was fine with it.
[SAW]Spitfire [SAW]Spitfire and if it’s a prolonged death you won’t remember the agony anyways... 🤔 😉
Dang, I forgot and just crashed my plane.
now everything is screwed , the world is going to crash and fall apart.....
Im dead too now. Manley failed us all.
Lacking a requirement to fly safe, the Insane American flew very deadly.
**Dual Vulcan sound*
**GAU-8 sound*
**GBU-16 sound*
**AGM-65 sound*
**Various explosions*
Damage: about $1200000, 12 wounded.
@@user2C47 Only about $1.2 million? Some missiles cost more than that. XD
@@user2C47 Many years ago my parents took me to an air show. I stood on the roof of our car (in those days cars were built of thicker steel) and clutching my camera awaited the Vulcan flyby. This is hard to put into words but maybe "awesome", "bonkers" and other adjectives will apply. As the Vulcan flew low overhead I nearly fell off the roof of the car, everything shook!
I got the the shot but the Vulcan looked quite small, it was only a basic camera. I can never forget that!
4:20 Those shock diamonds are sick! I never knew you could see them in thermals.
Also, nice.
I'm confused as to who teaches me about rocket science after the video ended.
I was equally confused about whether or not I should fly safe
Get a parrot it might repeat the finer points afterwards. Fly safe.
As a life long fan of space flight (watched first moon landing when I was 5), I have been slowly learning the technical aspects of rockets. My dad was a race engine builder. One of the things that allows a auto engine to work is that it cycles the most heat stresses parts. Getting a little time to cool makes the metals used able to deliver amazing performance. Sounds like it's time to apply the same idea to rocket engines.
Possibly - one of the things to understand about rockets is that they are:
1- not 'mass-produced' and therefore more given to using exotic materials than most engine blocks
2- focus more on constant thermodynamics and on thermal stress tolerances than 'duty cycles', whether milliseconds or minutes long; one of these ideas is found in nozzle designs, specifically in ablative vs. rigid, and the innovation of _regenerative cooling._
Dealing with detonations would require more of the engineering involved in harmonic balancing for driveshafts - dampeming/destroying vibrations & such.
If you haven't already, look up Scott's video on designing and testing the F-1 engine for the Saturn V.
@@HuntingTarg In response to point 1: It is the exhaust valves that are the most thermally and structurally stressed part in a 4-stroke piston engine. Modern race engines routinely make use of exotic alloys for the valve & seat. The amazing performance would not be possible without the time for cooling while closed.
In response to point 2: I have been well aware of the basic technical features of our current state of the art in rocket engines since I was in my twenties when the space shuttle was in development.
What I am trying to say is that intermittent combustion based on the detonation cycle (while fully aware of how hard it will be to work out the harmonic stresses) would allow us to leverage the use of the best materials even more than they are now. A 25% efficiency improvement is a BIG chunk of mass in fuel. Engines could be a lot heavier and still come out ahead.
@@markhatch1267 👍
We're roughly the same age and came into real-life rocketry through the same avenue - the Orbiter program.
I'm aware of the thermomechanical stresses on valve covers, and while you're quite right, 90+% of any production-line engine block is some variety of hardened steel or cast aluminum - economies of scale don't like high-tolerance, expensive parts. (I said 'more given to', since the quantities rocket motors are made in lines up with Supercars).
@@markhatch1267
I have a notion, that in a rocket engine that is typically designed for radially aymmetrical collimvariable flow, a 'rotating detonation' within the combustion chamber could introduce undesirable flow instabilities. While this may or may mot be a problem, I have to wonder what a rocket motor designed for vortical flow would be like - and _then_ wonder what detonation front would be like in _that_ engine... 🤷♂️💡
@@HuntingTarg Did you really mean valve covers, or is that a typo?
... so you're telling me I can put an explosive device that rotates under my Kerbals?
Well, you can always do that, but now you can put a static device under your Kerbals and have a constant explosion inside it spinning around.
Well, you have until his next video to try it since we don't have to "fly safe" until then :P
The device doesn't rotate, the shockwave of the explosion does
I suppose that's one way to get a DIY vasectomy :D
Sounds like a kraken summoning ritual to me!
Scott, you are so freaking concise....that was a GREAT video, amongst many of ur best. ....of which, you have many. Thx for all your hard work educating us laymen, to help us grapple these insanely intelligent concepts from other, alien-level-smart, humans.
Kudos, happy new year!
I guess there's no flying safe with a literal detonation constantly under your rear end.
V-1 did OK. The test versions were piloted. But deafening!
Nothing is safe if you consider all risks of technology used for transport. Even walking around is dangerous in it´s own way.
If Colin Furze sees this video, you just know that he's going to find pulsed detonation _way_ cooler than pulsed deflagration and he's going to build one. And do something ridiculous with it.
He's going to gravity feed it several thousand paintballs or something isn't he, destroyer of paintball worlds
That's it, folks, hypersonic unicycle.
I demand a pinned comment by Scott saying "I'm Scott Manley, fly safe".
Scott please, if you even are Scott! How can we know?!
Already watched this before, but now it's time for a refresh.
Are you me? Because that's why i am here. Also SM is the science instructor we need.
I sort of feel like this video didn't wrap up properly. I'm a little light headed in fact. What happened?
Yea, it almost seemed to end in the middle of a sentence
It was an editing mistake
[Removed]
@@user2C47 up
That pulse animation made me think about revving up a rocket like a car, lol.
I wonder if VTEC will kick in?
yo
"BAAAAAAH"
So who else is here now that Japan has actually flown a RDE?
Really? Any links?
Me!
Fantastic video, you explained this thoroughly and clearly. Im a Mechanical engineering major and you refreshed some of my thermo concepts while explaining something new. Thank you so much for putting this together!
Grats on 1 million subs I didn't notice!!
Finally!! A UA-cam content provider that knows the difference between an engine and a motor!!!
Are you Scott Manley? Do we fly safe?
I think he's Mott Scanley and we're to crash and burn. Good day, i go to my death now.
No. We fly deadly.
I Came from the future. Jaxa proved that the engine works in space. The test was a success.
You need to make a part 2 to this one. It is very interesting. I want to see the actual device(s) built.
One useful consequence of airbreathing RDEs possible not needing a compressor is that they then do not need a turbine either, as the sole purpose of the turbine is driving the compressor. This means you can run it much hotter, as you don't need to worry about the turbine blades melting.
Also, next video from Colin Furze: "hold my beer, let me build a detonation jet engine"
Tea with milk you mean. Underrated comment though. Need to ping Colin.
Jaxa demonstrated one in space. Time for an update
No flying safe with those detonation engines I guess :D
Makes sense.
That was some really neat photography with the bottle! Thanks!
WHO WOULD WIN:
A multi-stage turbine with hundreds of perfectly machined inconel blades
OR
A tube with some spark plugs and fuel injectors
Brrrr tube goes brap brap brap brap brap
10 trillion horsepower
I love watching these videos midday at work. It’s a mood.
Here after the JAXA flight!
Hey Scott! At 5:09 that's a model from the ANL, or Argonne National Laboratory! That's down the street from me here in Illinois!!
Yaaay! I've been geeking about this for long time
HOORAY! (Let's make it happen.)
Claxvii 177th **for
I hate your name. Remember, my opinion does not matter, I am just a random person on the internet. But I hate that name.
SECONDQUEST looking for who asked 🧐🔎
@@SECONDQUEST lol, we can't all be as cool as Scott Manley
If the tube is the right size you could tune the sound. Like a Harley. What you would hear is the vibration caused by the resonance frequency of the tube which would change as the flame front moves down the tube, Like a slide whistle.
They tested that (3:50) PDE at 5 am on a Saturday, a mile away from my apartment in Mojave. This woke me, terrified my cats, and pissed me off. It cut off after a few seconds, and a minute or three later did another burst. And again... the effect was like having a machine gun going off outside my window.
Long story short, they were confronted by a wild man wearing two layers of hearing protection who threw a total screaming obscenity-laden fit at them. Further static tests were done in the day time at the far side of the airport from the town.
do you have any video footage?
Just hearing protection? I mean, if it was early in the morning...
Yet concorde was not allowed in america.
@@tomstech4390 Concorde was used almost exclusively on the New York routes, so clearly allowed in America.
@@johndododoe1411 it wasn't allowed OVER the US
seriously the best rocket content! you make the concepts so readily available and easy to comprehend, thank you!!!
11:14 "Im Scott Manley, Fly Safe"
We all needed to hear it.
Thank you for another awesome video! After I saw some articles about this I have been patiently waiting for your video so I can actually understand it.
Last time I was this early you were making KSP tutorials
just from reading the title I thought this was one xD
This is a great introduction to RDTs. I am impressed with how you encapsulated the challenge of modeling this theoretically, especially with regard to the development of multiple detonation fronts.
Can’t wait to see A10 pointing its head down and take off vertically using its rotating detonation engine
Scott. You've gone and done it again and made a brilliant and educational video about my favourite things once again! Thank you!
I understand like 10% of what he says yet still watch his videos for some reason...
A friend is actually working on this at Argonne, totally were brainstorming this topic a couple summers back in a nearby Starbucks haha! Totally gonna show him your video Scott
Thanks Scott for your usual enlightening explanation for plebs like me. This looks like a real step up in efficiency so I am sure buckets of money are being thrown at it.
Everytime I see video of that prototype I think of Firefly, or back even further the original Jupiter II. :) Who knew Irwin Allen was a physics visionary?
Or the engines on Space Battleship Yamato.
Very well done. You had great graphics. They were very well leveraged and your teaching explanation was superb. Thank you.
Months ago I thought of an engine design with only one moving part, it has the core principles of functioning the way a Wankel Engine works, but doesn't have an odd circular path, the center part stays fixed in place while spinning, no shims to wear out, and it doesn't need oil, just grease for two bearings, Centrifugal forces bring in new fuel and air, also exhausting burnt fuel. This engine is also perfect for using HHO
Was hoping to hear you mention this new demonstration was completed at my alma mater, the University of Central Florida.
I apparently forgot to say 'Fly Safe' so I'm really off my game.
Came back here after seeing the NASA test footage! Thanks for making a great explanation!
I had been looking for a nice overview of this concept. Thanks for the excellent watch!
A real indicator of channel popularity is how many people comment "he didn't say fly safe!" :)
You presented the most simple explanation about Carnot cycle I have seen.
JAXA has tested a rotating detonation engine in space.
At 4:55, the long red tube is the igniter, starting with a deflagration that becomes a detonation, and launching that into the chamber. The main propellant feed is through the small axial tubes, at right angles to the travel of the detonation wave. The feed is subsonically supplying the blue cool mix, which the shock travels through at mach 2 to 5 or so. Note that at 5:19 the two shocks coalesce into one stronger shock after a few revolutions, a tiny fraction of a second in real time. As long as the chamber is not too short, the feed mix can't escape without getting shocked and burned as the wave comes around.
0:17 100 kilograms of thrust Scott? Don't you mean 100 kN of thrust? or 100 kgf?
Absolutely excellent! Best explanation of detonation and deflagration I've ever seen. Thanks!
They’ll need to rebrand this engine type to not use the word “detonation” if public approval is ever needed.
Vortical shock and awengine?
Humphrey Cycle Engine
They could use “Humphrey Cycle Engine”...
rapid combustion? edit: i like Humphrey Cycle lol much like a Wankel.
Kind of like the Magnetic Resonance Imagining (MRI) was renamed from Nuclear Resonance Imaging.
the physics is closely related to Tuned Headers on classic V8 engines... where cam timing is generally critical. JFF, BMW "airhead" motorcycles use strategically-located "balancer tubes" on their exhaust systems.... exhaust pipe length... even muffler-end shape... is also very important... to enhance exhaust system "scavenging".... on the aforementioned V8 engines, 4" pipes, vs. 3" exhaust systems can be catastrophically counter-productive (particularly at high RPM)... the same physics has also been applied to tuned intake manifolds - similarly, with commensurate cam/ignition timing (consider the physics of cold gases, vs. hot gases... along with atmospheric Nitrogen/oxygen dynamics). There have also been experiments with "acoustic turbo-chargers" for internal combustion engines. Ask any competent mechanic about the relationship of ignition timing vs. flame front (TDC, BTDC, ATDC)
That went over my head by about the same altitude as the ISS but it sounds interesting.
Thank you very much for making and sharing this video Scott Manley.
Time for a new Rotating Detonation Rocket Engine video!!
I study Aerospace engineering, at 3am on a Saturday night drunk eating chicken strips and watching detonation engines. my life has peaked.
I think I just found the best name for this one... The Ouroboros Drive
Your literally answering all the questions I had on Rotating Detonation Engines. Awesome stuff.
When going from linear to rotation, where do the valves go? Has the rotating engine 100 valves which sustain the pressure of the shock wave?
Here on the heels of the news that JAXA just successfully tested their RDE in space!
Very nice to have some heat engine thermodynamic cycles explained by charts. It is difficult to go into efficiency calculations without covering a lot of background material but pointing out that work corresponds to the enclosed area in P-V diagram as you did gives a very good idea of what is involved in increasing efficiency.
Any jet engine with the name "detonation" in it must be awesome.
I have been wondering about this and how it works for a LONNNNNGGGGGGGG time now. Thanks Scott for explaining! Favorite Channel! Fly safe man!
Japan just successfully tested this engine on a rocket.
Scott, might be time for an update on RDRE.
Agreed! Came here after seeing video of the recent NASA tests. I would love to see his input on the current state of RDEs.
Pretty much every rocket engine I have ever made was technically a non-rotating detonation engine. Or an enhanced deflagration engine, depending on how fast they disassembled themselves
The technical term is 'pulse detonation engine' with the number of pulses being one.
@@scottmanley How Long Do You Think Realistically It Will Be Scott Before We See These Rotating Detonation Engines AND Aerospike Engines Used In New Launch Vehicles And Spacecraft ? ? ?
Made think... Was the V1 sort of utilizing detonation? On the other hand, you do your most to avoid detonation mode in your car engine cylinders. Seek service, if you hear a certain kind of knocking.
"enthalpy" - a new word for me - had to google that one.
Great slo-mo footage of your kitchen experiment. Interesting to see residual flame fronts continue to move around after the initial one.
(10:00) I love a good graph.
Sick video. I'm doing my PhD at Embry-Riddle and a few times a year I have to give tours of the Gas Turbine Lab.. there's a pulse detonation experiment that's just been sitting there for a few years with no grad student working on it and folks always ask lots of questions about it.. it has nothing to do with my research so I've been saying "I don't know" a lot. Now I can just brush up with this! Life hack
A rotating detonation combustion chamber seems almost ideal for an aerospike nozzle geometry...
The less confining geometry of the aerospike might actually iron out some instability problems of the revolving shock.
This is the Scott Manley I like.
1. Tells me something I didn't know before the video
2. Just technical enough to wet my engineer and mathematical whistle
3. The subject is interesting
4. Scott Manley isn't in a bath-robe
Wait, what? He's not wearing a bathrobe? Dammit, I didn't even notice he was *naked*...!!! =8oO
So when I used to drive my crappy car that pinged whenever I stepped on the gas, I actually had a fancy super-efficient detonation engine. Cool!
No
0:42 Bambi P.S. Excellent description of detonation vs deflagration. Detonation is when the reaction front moves faster than the local speed of sound, creating shock wave(s) and much higher resultant pressures.
I didn't feel safe at the end
I just read an article about hypersonic missiles and this video was attached. I want to let you know how helpful this explanation was. Thank you very much for this video. I have a small background in science, so this was a perfect introduction to the concept.
This constant volume heat delivery reminds me of the Otto cycle, which, for a given compression ratio, has higher efficiency than the Diesel cycle. Funny enough, you can't increase the compression ratio in an Otto engine too much because of, well... detonation :-)
Many of the problems of preignition and detonation have been solved with the HCCI Homogeneous Charge Compression Ignition. The charge is ignited by either injecting a easu to ignite liquid such as DME (Dimethy Ether) or manipulation of the air fuel ratio and exhaust gas re-circulation. The RCCI engine Reactivity Controlled Compression adds a spark plug. Daimler Benz was testing them in WW2 all the way to 40,000ft. Formula 1 use them and they are 45%-50% efficient. It's likely they will operate to 58% efficiency. Better than fuel cells.
I'm a simple man, a farmer and yet this stuff absolutely amazes me...... I'll be in my shop later messing with fire and telling my son to "hold my beer, watch this" and later tonight we'll be sitting in the ER and my wife will be saying "WTF were you thinking" ...... Thanks for posting another fun video, let's see what we can build now🎉
The japanese apparently pulled it off now.
I'm soooo happy you covered this! I was waiting...
I rewatched Scotts old video to hear him say, *"Im Scott Manley, FLYSAFE"*
indeed, he was Scott Manley Flysafe
Excellent. I read about the Japanese actually flying one of these today, and so I wanted to learn more about it. I should’ve known you’d have an old video about it!
This is so cool
"Rotating Detonation Engine" is what I named the first rocket I ever built in KSP
Experiment: 12" "woofer" placed "face-down" on a smooth surface; apply swept sine wave signal from audio amplifier; how much power can be applied to momentarily lift ( through air pressure)the woofer off of the surface... at what frequency would the speaker remain suspended, where it's momentary inertia would "hold' it in place, before it begins to fall back? try connecting a tuned tube to the back of the speaker... potentially off-setting the nodal/antinodal points. (bass-reflex speakers can stimulate an in-phase resonance... with up to 3dB gain @ Fs/ Fso)... placing speaker "face up" on a scale (to measure force in grams) could lead to further insight(s)... just for fun, add a second woofer to the other end of the tube and experiment with phase alignment... nodal at the bottom, antinodal at the top...