6 ms·

Dr. Brownlee himself (the guy who designed the experiment) said that the plate was vaporized by the atmosphere and never got to space. Sorry for the buzzkill,

Dr. Brownlee himself (the guy who designed the experiment) said that the plate was vaporized by the atmosphere and never got to space. Sorry for the buzzkill, folks. https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_...

paulsutter 9y ago
You're misquoting the article: > Dr. Brownlee believes that the plate did not leave the atmosphere, as it may even have been vaporized by compression heating of the atmosphere due to its high speed.
- lotu 9y ago
  Well it sounds like the the only reasonable, responsible course of action is to replicate the original test but use modern high speed recording equipment to determine what would happen to that steel plate.
  - gambiting 9y ago
    How critical is the nuclear explosion in this experiment? Could you use an equivalent traditional explosive? 1KT explosion can be achieved without going nuclear.
    - flashdance 9y ago
      According to the wiki page the Pascal-B test was the equivalent of 300 tons of TNT.
      - solotronics 9y ago
        hold my beer
    - evan_ 9y ago
      I'm not a physicist but as far as I know a nuclear explosion releases its energy much more quickly than e.g. TNT, so just releasing the same number of joules wouldn't exactly duplicate the test unless you were able to release them in the same number of nanoseconds.
      - deleted 9y ago
        [deleted]
  - careersuicide 9y ago
    This video https://www.youtube.com/watch?v=T2orn6T2QFM https://www.youtube.com/watch?v=T2orn6T2QFM is a good DIY experiment along those lines and is interesting if not necessarily correct at the nuclear scale.
- mark-r 9y ago
  I'm curious, what speed is necessary for compression heating to be a significant factor? Obviously a regular rocket doesn't melt on its way into orbit, while it does need special protection for the trip back.
  - GlenTheMachine 9y ago
    Rockets do actually heat in flight. But their launch profile is carefully chosen to keep the heating to managable levels. Liquid fuel rockets typically throttle down somewhere around a minute after launch, at a point called "max-Q", which is the point of maximum aerodynamic pressure. They throttle back up again once they have gotten above enough of the atmosphere. As a point of reference, the SR-71 was one of the first major aircraft programs to use titanium extensively, the reason being that at the speeds the SR-71 flew, aluminum couldn't maintain structural stability due to the heat. And the SR-71 was "only" a Mach 3 airplane, flying at "only" 60,000 to 80,000 feet. It's fuselage would reach nearly 600 degrees. An orbital launch vehicle typically reaches Mach 3 very roughly that same altitude, or somewhat higher (the figure I can find is Mach 4.5 at 28 nautical miles, which by interpolation I'm guessing is Mach 3 at between ten to twenty nautical miles; ten nautical miles is roughly 60,000 feet).
    - orclev 9y ago
      Another bit about the SR-71 (and supposedly concordes) is that their structures are designed with tolerances based around the forces they experience at speed. The effect of which is that when sitting on the ground not going anywhere there are gaps between some parts, and others are tightly compressed together (and then separate while traveling at speed). I don't remember if it was the last concorde, or one of the SR-71s, but there's a story out there about the pilot on its final flight sticking his hat into a gap in the cockpit, which on landing promptly closed up permanently sealing his hat in place inside of the cockpit (he did it on purpose to commemorate the last flight). Similarly there are stories out there that claim the SR-71 leaked fuel like a sieve while sitting on the ground because it needed the atmospheric heating from going supersonic to seal up all the various fittings in its fuel system.
- deleted 9y ago
  [deleted]
NegativeLatency 9y ago
Interestingly those kind of speeds could put it on the speed record list (if it was a vehicle) https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#Relative_to_Earth https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#...

paulsutter 9y ago

You're misquoting the article: > Dr. Brownlee believes that the plate did not leave the atmosphere, as it may even have been vaporized by compression heating of the atmosphere due to its high speed.

lotu 9y ago
Well it sounds like the the only reasonable, responsible course of action is to replicate the original test but use modern high speed recording equipment to determine what would happen to that steel plate.
- gambiting 9y ago
  How critical is the nuclear explosion in this experiment? Could you use an equivalent traditional explosive? 1KT explosion can be achieved without going nuclear.
  - flashdance 9y ago
    According to the wiki page the Pascal-B test was the equivalent of 300 tons of TNT.
    - solotronics 9y ago
      hold my beer
  - evan_ 9y ago
    I'm not a physicist but as far as I know a nuclear explosion releases its energy much more quickly than e.g. TNT, so just releasing the same number of joules wouldn't exactly duplicate the test unless you were able to release them in the same number of nanoseconds.
    - deleted 9y ago
      [deleted]
- careersuicide 9y ago
  This video https://www.youtube.com/watch?v=T2orn6T2QFM https://www.youtube.com/watch?v=T2orn6T2QFM is a good DIY experiment along those lines and is interesting if not necessarily correct at the nuclear scale.
mark-r 9y ago
I'm curious, what speed is necessary for compression heating to be a significant factor? Obviously a regular rocket doesn't melt on its way into orbit, while it does need special protection for the trip back.
- GlenTheMachine 9y ago
  Rockets do actually heat in flight. But their launch profile is carefully chosen to keep the heating to managable levels. Liquid fuel rockets typically throttle down somewhere around a minute after launch, at a point called "max-Q", which is the point of maximum aerodynamic pressure. They throttle back up again once they have gotten above enough of the atmosphere. As a point of reference, the SR-71 was one of the first major aircraft programs to use titanium extensively, the reason being that at the speeds the SR-71 flew, aluminum couldn't maintain structural stability due to the heat. And the SR-71 was "only" a Mach 3 airplane, flying at "only" 60,000 to 80,000 feet. It's fuselage would reach nearly 600 degrees. An orbital launch vehicle typically reaches Mach 3 very roughly that same altitude, or somewhat higher (the figure I can find is Mach 4.5 at 28 nautical miles, which by interpolation I'm guessing is Mach 3 at between ten to twenty nautical miles; ten nautical miles is roughly 60,000 feet).
  - orclev 9y ago
    Another bit about the SR-71 (and supposedly concordes) is that their structures are designed with tolerances based around the forces they experience at speed. The effect of which is that when sitting on the ground not going anywhere there are gaps between some parts, and others are tightly compressed together (and then separate while traveling at speed). I don't remember if it was the last concorde, or one of the SR-71s, but there's a story out there about the pilot on its final flight sticking his hat into a gap in the cockpit, which on landing promptly closed up permanently sealing his hat in place inside of the cockpit (he did it on purpose to commemorate the last flight). Similarly there are stories out there that claim the SR-71 leaked fuel like a sieve while sitting on the ground because it needed the atmospheric heating from going supersonic to seal up all the various fittings in its fuel system.
deleted 9y ago
[deleted]

NegativeLatency 9y ago

Interestingly those kind of speeds could put it on the speed record list (if it was a vehicle) https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#Relative_to_Earth https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#...