4 ms·

This is pretty "out there." Conceptually it makes sense but the comment in the article that carrying along a power supply to make this practical cuts back on th

This is pretty "out there." Conceptually it makes sense but the comment in the article that carrying along a power supply to make this practical cuts back on the efficiency. That said, the idea of super heating the air in front of the leading edge so that the dense air in front goes around seems pretty amazing. But I am not sure I understand how the same super heated air doesn't result in the same heating they were trying to avoid.

m4rtink 6y ago
Isn't this basically what the supercavitating Shkval torpedo does ? https://en.m.wikipedia.org/wiki/VA-111_Shkval https://en.m.wikipedia.org/wiki/VA-111_Shkval Only this time in air and using plasma instead of pressurized gas - preatty high tech. As for the power source, I guess they could use chemical lasers. Also the faster it can get the less time the lasers need to run.
- jojobas 6y ago
  Soviets were working on plasma drag reduction as well, didn't get too far.
- techdragon 6y ago
  Yes, It is actually. I wound up pretty far down this rabbit hole while learning about re-entry dynamics. The issue with “normal” hypersonic drag is the pressure shock front is “attached” to the surface of your “plane”. Which means that location is subjected to the thermal loads induced by the shockwave compression. What they discovered back in the early days of manned space flight (and icbm development) was that there is a relationship between how pointy you make something and the detachment of that shockwave. The bi-conic space capsule shape were all familiar with from the Gemini and Apollo program pushes the hypersonic shock wave completely off the surface! This means that you have way less heat to work deal with... but that shape is ideal for re-entry, when your trying to slow down. Not for when your trying to go faster. As a result there’s been heaps of aerodynamic engineering research since the 60s on how to get similar detached shock fronts while maintaining aerodynamic control over the vehicle. One significant development was the drag reducing aerospike. https://en.wikipedia.org/wiki/Drag-reducing_aerospike https://en.wikipedia.org/wiki/Drag-reducing_aerospike and another was the creation of a lot of a lot of plasma physics funding ;-) All jokes aside, the other outcome was the realisation that by artificially inducing a plasma at a lower temperature in front of the airframe they could both aim to control the shape, composition and temperature of the plasma while also improving aerodynamic control, and minimising plasma heating and RF blocking, radar signature, all while still benefiting from the re-entry like effect of pushing the heated shock front entirely off the airframe. There’s been a fair bit of small scale wind tunnel testing over the years, some of which is available in the NASA technical reports server archives.
berkut 6y ago
I'm sure there's been at least research in this area since the 1980s - I remember hearing about it when I worked in the Defence industry on weapons systems in the early 2000s as an improvement over the default static "Spike" on existing high-mach-number vehicles (ICBMs for example)... As mentioned in the other comment, Supercavitation for torpedoes have existed for a while, which in some ways can likely be argued to be similar (altering the medium the body is in to reduce drag).

m4rtink 6y ago

Isn't this basically what the supercavitating Shkval torpedo does ? https://en.m.wikipedia.org/wiki/VA-111_Shkval https://en.m.wikipedia.org/wiki/VA-111_Shkval Only this time in air and using plasma instead of pressurized gas - preatty high tech. As for the power source, I guess they could use chemical lasers. Also the faster it can get the less time the lasers need to run.

jojobas 6y ago
Soviets were working on plasma drag reduction as well, didn't get too far.
techdragon 6y ago
Yes, It is actually. I wound up pretty far down this rabbit hole while learning about re-entry dynamics. The issue with “normal” hypersonic drag is the pressure shock front is “attached” to the surface of your “plane”. Which means that location is subjected to the thermal loads induced by the shockwave compression. What they discovered back in the early days of manned space flight (and icbm development) was that there is a relationship between how pointy you make something and the detachment of that shockwave. The bi-conic space capsule shape were all familiar with from the Gemini and Apollo program pushes the hypersonic shock wave completely off the surface! This means that you have way less heat to work deal with... but that shape is ideal for re-entry, when your trying to slow down. Not for when your trying to go faster. As a result there’s been heaps of aerodynamic engineering research since the 60s on how to get similar detached shock fronts while maintaining aerodynamic control over the vehicle. One significant development was the drag reducing aerospike. https://en.wikipedia.org/wiki/Drag-reducing_aerospike https://en.wikipedia.org/wiki/Drag-reducing_aerospike and another was the creation of a lot of a lot of plasma physics funding ;-) All jokes aside, the other outcome was the realisation that by artificially inducing a plasma at a lower temperature in front of the airframe they could both aim to control the shape, composition and temperature of the plasma while also improving aerodynamic control, and minimising plasma heating and RF blocking, radar signature, all while still benefiting from the re-entry like effect of pushing the heated shock front entirely off the airframe. There’s been a fair bit of small scale wind tunnel testing over the years, some of which is available in the NASA technical reports server archives.

berkut 6y ago

I'm sure there's been at least research in this area since the 1980s - I remember hearing about it when I worked in the Defence industry on weapons systems in the early 2000s as an improvement over the default static "Spike" on existing high-mach-number vehicles (ICBMs for example)... As mentioned in the other comment, Supercavitation for torpedoes have existed for a while, which in some ways can likely be argued to be similar (altering the medium the body is in to reduce drag).