Hypersonic Propulsion News and Developments

A brief article in The Economist on MHD for steering hypersonic aircraft. Not a great deal of technical depth but it gives a name to watch.

www.economist.com

The challenges of steering a hypersonic plane

At five times the speed of sound, a craft flies through plasma, not air
www.economist.com www.economist.com

Steering hypersonically using conventional control surfaces, like wings and ailerons, is out of the question. The forces and heat involved would destroy them. Smaller versions called trim tabs can help a bit. But what is really needed is a different approach. And, as he told delegates at last week’s meeting of the American Association for the Advancement of Science in Denver, Hisham Ali of the University of Colorado, Boulder, is one of those proposing just that. He thinks the answer is to be found in a field called magnetohydrodynamics.

Aerodynamics manipulates gases. Magnetohydrodynamics manipulates plasmas. These are gas-like fluids whose atoms have been ionised by losing some or all of their electrons—as happens to the air, by frictional heating, when an object travels hypersonically through the atmosphere. Since a plasma’s particles are electrically charged (the electrons negatively and the ions positively), their flow pattern over a hypersonic vehicle could be altered using a set of electromagnets within. Changing the plasma flow would also change the craft’s trajectory, at a rate controllable via the electromagnets. Additionally, the plasma’s passage could be harnessed to produce electricity inside the craft, perhaps powering the magnets.
 
The front of the fictional Orion III had what looked like a Supersaber intake…here something like that could be a plasma Skvall type deal.

If you have a plasma handling system..might you need a bustle trunk tail for coils?
 
Proof of concept of aircraft with no moving control surfaces relying on blown gas has been done, BAE had the MAGMA drone demonstrator which flew in 2019 and used supersonic engine exhaust gases redirected into and out of the wings to change airflow over them (so you could lower the air pressure on one wing while raising it on the other and vice versa) and additionally blown into the engine exhaust nozzle for thrust vectoring and Boeing subsidiary Aurora is currently building the X-65 for DARPA which operates on similar principals (uses bottled gas rather than redirected engine exhaust) though it hasnt flown yet and has a backup set of physical control surfaces in case something goes wrong in testing unlike the aircraft BAE flew.

Edit: After looking it up BAE did the Phase 0 design library and airflow modelling for the X-65 while Aurora are doing the Phase 1 detailed aircraft design up to preliminary design review and phase 2 development of flight software and ground testing of controls while the phase 3 aircraft construction and flight testing hasnt been awarded yet.
 
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MagnetoHydroDynamics (MHD) involves generating magnetic fluxes to actionate air flows. Nothing like pulsating gases.
Note that the idea have been discussed for long. I have been mentioning this for long myself, including using the shrouding effect of plasma layers around an hypersonic body to generate a degree of stealth (something I call Hyperstealth).

Reciprocally, hypersonic bodies are potentially exposed to external actuation of their surrounding airflow to generate soft/hard kills (also long discussed, early on by me).

See as attached file and example of reducing the heat load of re-entry vehicle by using MHD to lesser drag, hence heat.
 

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The BOLT-1B hypersonic vehicle has had a successful test-flight, from Defense Updates:


US Air Force’s hypersonic test vehicle BOLT-1B has conducted its successful flight. The flight was carried out over Norway on September 2.
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The test vehicle lifted off from the Andøya Space Sub-Orbital launch site at 11:41:01 local time and reached an apogee of 157 miles (254 kilometers) before safely splashing down inside the impact and dispersion area.As planned, the test concluded with BOLT-1B impacting the ocean approximately 115 miles (185 kilometers) offshore.
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BOLT-1B completed all test objectives, according to reports. The experimental vehicle traveled over the Norwegian Sea at Mach 7.2 and provided a stream ofimportant data on the physics of airflow at hypersonic speeds.
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The project is coordinated by the Air Force Office Scientific Research from the United States and is carried out by Johns Hopkins Applied Physics Laboratory (APL), the Air Force Research Laboratory Aerospace Systems Directorate (AFRL/RQ), and the German Aerospace Center (DLR).
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In this video, Defense Updates analyzes why the successful test of the BOLT-1B hypersonic vehicle is awesome news for the U.S. ?
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#defenseupdates #hypersonicmissile #usmilitary
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Chapters:
00:11 INTRODUCTION
02:20 HYPERSONIC WEAPON
04:18 AFRL’s INSIGHTS
05:59 AID IN HYPERSONIC WEAPON DEVELOPMENT
06:52 ANALYSIS
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What is the advantage of an RDE over a scramjet? I get more compact, but does it have a much lower minimum speed for ignition?
 
Could this new propulsion system be installed on existing missiles such as the Jassm, Lrasm and Tomahawk, or as future upgrades for Hacm or various low-cost missiles such as those built by Aldurin?
 
Josh_TN said:
What is the advantage of an RDE over a scramjet? I get more compact, but does it have a much lower minimum speed for ignition?
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Its really just mechanical simplicity and therefore weight and cost savings (potentially some fuel efficiency savings from more complete fuel burn as well).
Its like lots of little miniature pulse jets each firing in succession so avoids the downsides of the one big pulse jet that it takes time to cycle the chamber. The downside compared to a scramjet is extra noise and potential non-uniform thrust or unreliability of missed ignitions like a engine with a faulty spark distributor.
 
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Lc89 said:
Could this new propulsion system be installed on existing missiles such as the Jassm, Lrasm and Tomahawk, or as future upgrades for Hacm or various low-cost missiles such as those built by Aldurin?
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No.
 
WatcherZero said:
Its really just mechanical simplicity and therefore weight and cost savings (potentially some fuel efficiency savings from more complete fuel burn as well).
Its like lots of little miniature pulse jets each firing in succession so avoids the downsides of the one big pulse jet that it takes time to cycle the chamber. The downside compared to a scramjet is extra noise and potential non-uniform thrust or unreliability of missed ignitions like a engine with a faulty spark distributor.
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A scramjet already has a similar lack of moving parts. The two big issues are volume - you need a long intake ramp and combustion chamber to completely burn hydrocarbons, even with pre cracking, and ignition speed - for a fixed inlet and combustor geometry, there is a narrow band of acceptable airflow. Mach 4+ at 50,000+ feet is the minimum, with increases in speed requiring increases in altitude to maintain a relatively steady volume of air.

Clearly the RDE is a much more compact design. My question is whether it lowers the speed threshold for ignition or if similar Mach 4 speeds are still needed.
 
Yes.
RDE provide lower speed efficient combustion than a ramjet for a less cavernous volume. Then the max efficient speed is well inside the range of a scramjet making them ideal for a combined propulsion device.
All the physical constraints combine better (more compact with less complexity) with a dual RDE / Scramjet when attached to a rocket booster. Ex.: hypersonic missile.

With a Turbojet / Scramjet compound, a Turborocket might be more suitable. Ex. : Hypersonic fighter.
 
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TomcatViP said:
Yes.
RDE provide lower speed efficient combustion than a ramjet for a less cavernous volume. Then the max efficient speed is well inside the range of a scramjet making them ideal for a combined propulsion device.
All the physical constraints combine better (more compact with less complexity) with a dual RDE / Scramjet when attached to a rocket booster. Ex.: hypersonic missile.

With a Turbojet / Scramjet compound, a Turborocket might be more suitable. Ex. : Hypersonic fighter.
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Couldn't you run an air-turbo-rocket with a rotating detonation combustor after the turbine?
 
Interesting suggestion.
Generally, elevated temperature decrease the detonation effect. But I would say that's highly dependent on local conditions.
What I could say is that flame propagation is highly dependent on the momentum of particles. With combustion gases, you'll have different species (unburned fuel, different ratio of combusted gases and then air) competing to rush around the compression part of the RDE and react differently to the addition of fuel. That would result in a stratified mix upstream of the detonation and probably a poor variation of pressure overall, very difficult to make stable and homogeneous in the RD part.

A quick search brings me this, which I don't have full access:

 
Couldn't an RDE combustion be combined with a compressor/turbine assembly?
 
techxplore.com

Simulations and diagnostics shed light on complex physics of hypersonic flight

Aerospace engineering has always had a preoccupation with speed. Now researchers at the University of Cincinnati are pushing the boundaries of what is possible, practical, reliable and safe at five times the speed of sound, or more than 3,800 mph.
techxplore.com techxplore.com

"This is just the beginning," Redding said. "Hypersonics is a multidisciplinary field of research that requires the insight of a passionate community intentionally pursuing the knowledge it has to go faster and higher."
 
This seems to the right thread for this video about NASA's Electric Arc Shock Tunnel at its' Ames facility, from Scott Manley:


The Electric Arc Shock Tunnel (EAST) at NASA Ames can generate hypervelocity shockwaves in test atmospheres to understand what happens during atmospheric entry. This system uses a capacitor bank that stored up to 1.25MegaJoules to drive a shockwave in a test gas then observe the light emitted.​
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This is essential to determining the radiative heating that will be experienced during atmospheric entry, and the facility at NASA Ames is the only one in the world that can even get close to the conditions experienced by probes to the gas giants.​
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This facility was originally built for the Apollo programme back in the 1960s but it's still going strong.
 
https://twitter.com/x/status/1989725508855287907
View: https://twitter.com/leap_71/status/1989725508855287907


Not designed by aliens. Designed by "the first AI that builds machines" as the press has called Noyron, our Large Computational Engineering Model. This hypersonic precooler we produced with @FarsoonAM uses a fractal folding algorithm to chill down superheated air.
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ChromeKiwi
@AshleyKillip

Ai engineered precooler. This is one thing i like about Ai being able to design new ways to do things and since it's computer based can likely do all its own flow path analysis and model simulations for total efficiency or material weight without compromising the structure. Maximising form and function.
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