7 ms·

Breakthrough in 'detonating' hypersonic propulsion

113 points by carabiner 3y ago

carabiner 3y ago
Basically this is the first demonstrated propulsion method that really supersedes the SR-71's J58 + inlet. Instead of 0 to mach 3, this is like 0 to mach 10.
zactato 3y ago
I learned about RDC engines from this great video https://youtu.be/fRMMSyCcTDI?si=ccXeWtJ7N3oibyuH https://youtu.be/fRMMSyCcTDI?si=ccXeWtJ7N3oibyuH
- nomel 3y ago
  Here's a great deep dive, into the complexities: https://www.youtube.com/watch?v=Ws4kbgfpKCw https://www.youtube.com/watch?v=Ws4kbgfpKCw
  - dylan604 3y ago
    They should come out with a sweatshirt with the name printed in reverse like on an ambulance to not look so cheap production quality.
  - nielsole 3y ago
    After watching these two videos it's unclear to me what is hard about building such engines. The numerical model seemed pretty pedestrian compared to anything else in fluid dynamics. If I understood correctly the detonation is basically stable depending on the right reactant intake. So you wouldn't need submillisecond active control or anything like that. Is the heat the biggest problem? Do RDE get that much hotter than other engines or produce more vibrations?
    - NewLogic 3y ago
      I haven't ran the numbers or anything but I would assume supplying the high PSI oxygen for a long burn duration would be a considerable engineering challenge. You would need a system to jump start with bottled oxygen and then a heat exchanger in the combustion chamber to gasify LOX once stable detonation is reached. It is likely New Space companies have run the numbers on engine weight versus a contemporary staged combustion engine and found it to be little to no efficiency gain.
fnorder 3y ago
This sounds like something straight from descriptions of the Aurora Project that I heard decades ago.
- kurthr 3y ago
  The rumors in Aviation Leak were that (one of the) Arora was an external burn (not RDL) unmanned aircraft around Mach 5-6. The "skyquakes" described here set off the local seismometers at regular intervals (eg 7am monday and wednesday), which doesn't normally happen. By looking at the parabolas (conic shockwave intersection with earth) of the arrival at an array of seismometers one could estimate the angle of the shockwave (Mach) and the angle relative the surface (attack angle). My memory is that it was accelerating Mach 3-5 at an angle over 45 deg. https://www.defenceaviation.com/sr-91-aurora-aircraft/ https://www.defenceaviation.com/sr-91-aurora-aircraft/
  - robterrell 3y ago
    Aurora, that's a blast from the past. Donuts-on-a-rope contrails, right?
Out_of_Characte 3y ago
Curious why they mention mach limits with their ramjet/rde I've seen them work under subsonic air conditions. Makes me wonder what the limiting factor is of rde under subsonic speeds. To me,the rde always seemed like the holy grail of propulsion even under subsonic speeds because of the significantly higher exhaust velocity. Something even rocket engines could benefit from due to the better ISP characteristics in low and high atm pressures.
- ballooney 3y ago
  This is an air breathing rde, you have likely seen rdes with seperate oxidiser injection, more like a rocket engine.
- icegreentea2 3y ago
  I think the mach limit part was referencing the "ramjet" portion. The description seems to say that there's also a rde turbine to handle subsonic and low supersonic flight.
UberFly 3y ago
I hope they have a good firewall.
idontwantthis 3y ago
I remember Scott Manley saying this was only like a 5% efficiency gain for rockets. Any idea if it’s bigger for air breathing jets?
- cf1241290841 3y ago
  Given how much of the total weight of a rocket is required for fuel, 5% is massive.
  - idontwantthis 3y ago
    I mean its a big deal on a statistical level for many launches adding up, but it’s not exactly going to take us somewhere we can’t otherwise go.
    - ben_w 3y ago
      It kinda does, a bit. "5%" by itself is a little vague thanks to the rocket equation relating delta-v and payload fraction with an exponential.
    - shikon7 3y ago
      It does for rockets with many stages, as the lower stages will get an exponential benefit.
dataflow 3y ago
Off topic but why is hypersonic Mach 5 and above? Anything special about that threshold, or was it chosen arbitrarily?
- rocqua 3y ago
  If I recall scott Manley correctly, mach 5 is roughly the speed only reachable by ramjets. And also roughly the speed where aerodynamic heating starts generating plasma around the airframe. Hence getting to mach 5 requires solving two problems that don't really need to be solved for slower speeds.
  - stavros 3y ago
    "You can't reach this speed easily" doesn't sound like a problem that's specific to Mach 5+.
    - geraldhh 3y ago
      yet, here we are
      - stavros 3y ago
        Yet here we are, at a problem that's not specific to Mach 5+?
    - vGPU 3y ago
      It’s not reaching it, it’s staying there. The heat and plasma represent enormous challenges. Comms are incredibly difficult to maintain, for example.
      - stavros 3y ago
        Isn't this the same with any speed, though? We've always had trouble breaking the next record.
        3y ago
sn00tz00t 3y ago
If they want to increase power is the RPM of the detonation wave increased?
rbanffy 3y ago
I know this is all weapons related (and mostly single-use weapons), but I long for the supersonic passenger jets of my childhood. Or even subsonic ones with 5% more legroom.
- engineer_22 3y ago
  Haven't you heard!? It's coming! These guys are building it right now https://boomsupersonic.com/commercial https://boomsupersonic.com/commercial
  - rbanffy 3y ago
    They won’t replace the 777 and A380 though. I would like a supersonic plane that could take 300+ passengers on long routes.
    - engineer_22 3y ago
      That's a cogent point. To add to that, I think the supersonic planes aren't proposed for flight over populated areas - but for transoceanic flight.
      - rbanffy 3y ago
        > but for transoceanic flight. That's fine. With the exception of routes that go from Europe to East Asia over the continent, there is no shortage of gruelingly long flights between South America and Australia, New Zealand and Europe that are done mostly over the ocean. And that doesn't take into account the recent developments in reducing sonic booms.
- ghaff 3y ago
  As another comment notes, various companies take a shot at this from time to time. It's more an economic problem than a pure engineering one. When you can buy lie flat seating on most long distance routes (and even sort of cabins on some), it's not clear how big the market is for supersonic tickets that may cost even more (as was the case with the Concorde) and probably will have less range. Legroom isn't a problem on bigger jets. You just need to pay a big premium for it. I also assume there's less market these days for flying NYC to London to shake hands and sign a deal over lunch and be back home for dinner.
kvetching 3y ago
America has strategic ambiguity when it comes to hypersonic tech.. It appears that America is behind. They keep reporting their hypersonic programs are failing. The best tech is not presented to the public. What happened with the NDAA makes it clear that defense contractors are hiding advanced technology related to UAPs. The UAP Disclosure Act unanimously passed the Senate. When it got to the House, it was completely gutted by the man who is Lockheed's #1 Lobbying Recipient (Mike Turner). Here is the response from the Senate when the House killed the bill: https://www.youtube.com/watch?v=N0HoXkQXpVE https://www.youtube.com/watch?v=N0HoXkQXpVE So it's clear, defense contractors have advanced technology that not even Congress or the President can learn about.
- _8j50 3y ago
  > defense contractors have advanced technology that not even Congress or the President can learn about. Who would they sell it to? And why is any of what you said a bad thing?
- dotnet00 3y ago
  The line I've often heard from defense enthusiasts is that America appears behind on hypersonics because they're aiming for "true" hypersonic weapons, ie ones which are capable of a wide range of navigation while in powered hypersonic flight, as that's what actually makes the concept so potent, by making the missile so fast and unpredictable that current air defense systems would struggle to intercept it. Without controlled navigable flight, "hypersonics" are much simpler, as you basically just have a ballistic missile, which can still be intercepted by traditional air defense (Russia's Kinzal being an example of this kind of so-called hypersonic missile).

113 points by carabiner 3y ago

Basically this is the first demonstrated propulsion method that really supersedes the SR-71's J58 + inlet. Instead of 0 to mach 3, this is like 0 to mach 10.

zactato 3y ago

I learned about RDC engines from this great video https://youtu.be/fRMMSyCcTDI?si=ccXeWtJ7N3oibyuH https://youtu.be/fRMMSyCcTDI?si=ccXeWtJ7N3oibyuH

nomel 3y ago
Here's a great deep dive, into the complexities: https://www.youtube.com/watch?v=Ws4kbgfpKCw https://www.youtube.com/watch?v=Ws4kbgfpKCw
- dylan604 3y ago
  They should come out with a sweatshirt with the name printed in reverse like on an ambulance to not look so cheap production quality.
- nielsole 3y ago
  After watching these two videos it's unclear to me what is hard about building such engines. The numerical model seemed pretty pedestrian compared to anything else in fluid dynamics. If I understood correctly the detonation is basically stable depending on the right reactant intake. So you wouldn't need submillisecond active control or anything like that. Is the heat the biggest problem? Do RDE get that much hotter than other engines or produce more vibrations?
  - NewLogic 3y ago
    I haven't ran the numbers or anything but I would assume supplying the high PSI oxygen for a long burn duration would be a considerable engineering challenge. You would need a system to jump start with bottled oxygen and then a heat exchanger in the combustion chamber to gasify LOX once stable detonation is reached. It is likely New Space companies have run the numbers on engine weight versus a contemporary staged combustion engine and found it to be little to no efficiency gain.

fnorder 3y ago

This sounds like something straight from descriptions of the Aurora Project that I heard decades ago.

kurthr 3y ago
The rumors in Aviation Leak were that (one of the) Arora was an external burn (not RDL) unmanned aircraft around Mach 5-6. The "skyquakes" described here set off the local seismometers at regular intervals (eg 7am monday and wednesday), which doesn't normally happen. By looking at the parabolas (conic shockwave intersection with earth) of the arrival at an array of seismometers one could estimate the angle of the shockwave (Mach) and the angle relative the surface (attack angle). My memory is that it was accelerating Mach 3-5 at an angle over 45 deg. https://www.defenceaviation.com/sr-91-aurora-aircraft/ https://www.defenceaviation.com/sr-91-aurora-aircraft/
- robterrell 3y ago
  Aurora, that's a blast from the past. Donuts-on-a-rope contrails, right?

Out_of_Characte 3y ago

Curious why they mention mach limits with their ramjet/rde I've seen them work under subsonic air conditions. Makes me wonder what the limiting factor is of rde under subsonic speeds. To me,the rde always seemed like the holy grail of propulsion even under subsonic speeds because of the significantly higher exhaust velocity. Something even rocket engines could benefit from due to the better ISP characteristics in low and high atm pressures.

ballooney 3y ago
This is an air breathing rde, you have likely seen rdes with seperate oxidiser injection, more like a rocket engine.
icegreentea2 3y ago
I think the mach limit part was referencing the "ramjet" portion. The description seems to say that there's also a rde turbine to handle subsonic and low supersonic flight.

UberFly 3y ago

I hope they have a good firewall.

idontwantthis 3y ago

I remember Scott Manley saying this was only like a 5% efficiency gain for rockets. Any idea if it’s bigger for air breathing jets?

cf1241290841 3y ago
Given how much of the total weight of a rocket is required for fuel, 5% is massive.
- idontwantthis 3y ago
  I mean its a big deal on a statistical level for many launches adding up, but it’s not exactly going to take us somewhere we can’t otherwise go.
  - ben_w 3y ago
    It kinda does, a bit. "5%" by itself is a little vague thanks to the rocket equation relating delta-v and payload fraction with an exponential.
  - shikon7 3y ago
    It does for rockets with many stages, as the lower stages will get an exponential benefit.

dataflow 3y ago

Off topic but why is hypersonic Mach 5 and above? Anything special about that threshold, or was it chosen arbitrarily?

rocqua 3y ago
If I recall scott Manley correctly, mach 5 is roughly the speed only reachable by ramjets. And also roughly the speed where aerodynamic heating starts generating plasma around the airframe. Hence getting to mach 5 requires solving two problems that don't really need to be solved for slower speeds.
- stavros 3y ago
  "You can't reach this speed easily" doesn't sound like a problem that's specific to Mach 5+.
  - geraldhh 3y ago
    yet, here we are
    - stavros 3y ago
      Yet here we are, at a problem that's not specific to Mach 5+?
  - vGPU 3y ago
    It’s not reaching it, it’s staying there. The heat and plasma represent enormous challenges. Comms are incredibly difficult to maintain, for example.
    - stavros 3y ago
      Isn't this the same with any speed, though? We've always had trouble breaking the next record.
      - 3y ago

sn00tz00t 3y ago

If they want to increase power is the RPM of the detonation wave increased?

rbanffy 3y ago

I know this is all weapons related (and mostly single-use weapons), but I long for the supersonic passenger jets of my childhood. Or even subsonic ones with 5% more legroom.

engineer_22 3y ago
Haven't you heard!? It's coming! These guys are building it right now https://boomsupersonic.com/commercial https://boomsupersonic.com/commercial
- rbanffy 3y ago
  They won’t replace the 777 and A380 though. I would like a supersonic plane that could take 300+ passengers on long routes.
  - engineer_22 3y ago
    That's a cogent point. To add to that, I think the supersonic planes aren't proposed for flight over populated areas - but for transoceanic flight.
    - rbanffy 3y ago
      > but for transoceanic flight. That's fine. With the exception of routes that go from Europe to East Asia over the continent, there is no shortage of gruelingly long flights between South America and Australia, New Zealand and Europe that are done mostly over the ocean. And that doesn't take into account the recent developments in reducing sonic booms.
ghaff 3y ago
As another comment notes, various companies take a shot at this from time to time. It's more an economic problem than a pure engineering one. When you can buy lie flat seating on most long distance routes (and even sort of cabins on some), it's not clear how big the market is for supersonic tickets that may cost even more (as was the case with the Concorde) and probably will have less range. Legroom isn't a problem on bigger jets. You just need to pay a big premium for it. I also assume there's less market these days for flying NYC to London to shake hands and sign a deal over lunch and be back home for dinner.

kvetching 3y ago

America has strategic ambiguity when it comes to hypersonic tech.. It appears that America is behind. They keep reporting their hypersonic programs are failing. The best tech is not presented to the public. What happened with the NDAA makes it clear that defense contractors are hiding advanced technology related to UAPs. The UAP Disclosure Act unanimously passed the Senate. When it got to the House, it was completely gutted by the man who is Lockheed's #1 Lobbying Recipient (Mike Turner). Here is the response from the Senate when the House killed the bill: https://www.youtube.com/watch?v=N0HoXkQXpVE https://www.youtube.com/watch?v=N0HoXkQXpVE So it's clear, defense contractors have advanced technology that not even Congress or the President can learn about.

_8j50 3y ago
> defense contractors have advanced technology that not even Congress or the President can learn about. Who would they sell it to? And why is any of what you said a bad thing?
dotnet00 3y ago
The line I've often heard from defense enthusiasts is that America appears behind on hypersonics because they're aiming for "true" hypersonic weapons, ie ones which are capable of a wide range of navigation while in powered hypersonic flight, as that's what actually makes the concept so potent, by making the missile so fast and unpredictable that current air defense systems would struggle to intercept it. Without controlled navigable flight, "hypersonics" are much simpler, as you basically just have a ballistic missile, which can still be intercepted by traditional air defense (Russia's Kinzal being an example of this kind of so-called hypersonic missile).