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I think creating cannons along the designs of Gerald Bull would be more promising. Just huck cube sats into orbit. Obviously you'd probably want a cube sat with

I think creating cannons along the designs of Gerald Bull would be more promising. Just huck cube sats into orbit. Obviously you'd probably want a cube sat with no moving parts or something that could withstand what I'd assume to be like 10K G's.

TheLoafOfBread 4y ago
Even if something is rated on i.e. 1000G it is rated for a very short time, like a shock or a fall on the ground. Which from my perspective is the problem of whole concept described in the video. In 5:55 minute mark, video is describing force applied on the payload will reach from 1G to 10000G, but how long does this take? 10 minutes? 30 minutes? An hour? Can you have a payload which will be able to withstand 1000G+ for minutes? Contrary to big cannons, like [0] there would be forces of 10000G only for few milliseconds as shells are accelerating only during the time of being in the barrel. [0] https://en.wikipedia.org/wiki/Project_HARP https://en.wikipedia.org/wiki/Project_HARP
- gonzo41 4y ago
  I would guess you'd do something like try and cast any electrical components in something like a resin so it's just a solid brick that can handle the stresses. But 10k G is a lot.
  - TheLoafOfBread 4y ago
    Well problem is that this concept is supposed to replace 1st stage as it can reach only to 70km. What kind of 2nd stage rocket engine can survive such Gs? Solid booster which you can't control?
    - chasil 4y ago
      There is lengthy discussion at the end of the video on design changes, primarily for the reaction wheel. They conclude by placing a digital camera in their lab mockup and taking it to 10,000g. This probably would not have worked for a phone, but they seem quite confident.
    - adgjlsfhk1 4y ago
      They have the significant advantage that they get pretty much free mass before the fairing opens (since more mass reduces drag and they aren't fighting the rocket equation until they are out of the atmosphere). As such they can do things like heavily brace the inside of the nozzle without it hurting their payload capacity.
  - MichaelCollins 4y ago
    10k G should be doable, during WW2 the allies had radio proximity fuzes for artillery shells that exceeded that: https://en.wikipedia.org/wiki/Proximity_fuze https://en.wikipedia.org/wiki/Proximity_fuze
    - TheLoafOfBread 4y ago
      What about the rest of the satellite? Solar panels, antenna, engines?
      - MichaelCollins 4y ago
        It all seems generally dubious to me. But I think solar panels could survive that force if they were firmly supported inside the vehicle before launch; I don't think the acceleration itself would break the panels if they were prevented from flexing. For an engine, maybe solid fuel but the fuel itself would be structural. A pressure-fed liquid fuel engine might be easier, if you could get valves (and actuators for those valves) to survive that kind of force.
    - torginus 4y ago
      The problem is that this thing is supposed to throw a whole second stage rocket, with plumbing, turbopumps with moving parts, and fuel that sloshes around.
      - JumpCrisscross 4y ago
        > fuel that sloshes around Pressure and ballast balls.
    - morcheeba 4y ago
      That was one design that was extensively tested and then copied. Weight was no concern. Most satellites are unique, so the same can't be done. Besides being weight critical, every failed satellite becomes space junk.
      - 4y ago
  - Animats 4y ago
    Militaries have been shooting working electronics out of guns since WWII. The earliest versions were vacuum tube proximity fuses. The U.S, military has been shooting guided weapons out of guns since the 1970s. They work pretty well. This technology seems to be suited for launching moderate numbers of small satellites. It's not a huge win on launch cost over filling up a Falcon 9 with racks of small satellites. This competes with the Pegasus air-launch system, where a rocket is carried to high altitude by an aircraft. That works fine, and launches have been going on since the 1990s. But it's not a huge financial win. It's good to have a few competing technologies. Keeps the price down.
- Someone 4y ago
  One advantage this has over guns is that jerk (https://en.wikipedia.org/wiki/Jerk_(physics) https://en.wikipedia.org/wiki/Jerk_(physics)) is lower. I don’t know whether it makes a difference in survivability, but it seems to me that it would, at least somewhat, for some materials. But then, what do I know? Impact resistance typically is reported in gs, but that might be a simplification because, typically, the higher order time derivatives of position correlate well with acceleration.
  - JKCalhoun 4y ago
    I would invest in more rockoon research. More of an elegant way to sidestep the thick atmosphere we're straddled with rather than brute force it with cannons and such. https://en.wikipedia.org/wiki/Rockoon https://en.wikipedia.org/wiki/Rockoon
    - aaronblohowiak 4y ago
      Makes a lot of sense to me — make the atmosphere do a lot of the heavy lifting rather than fuel.
- bergenty 4y ago
  The rate of change of acceleration is going to be massive in a cannon though. That intuitively feels worse than very high acceleration but with a more gradual increase in the rate of change.
thrown_22 4y ago
Or a closed magnetic rail which you unlatch when you fire. The idea that you should use an actual spinning arm is needed is what everyone has a problem with. A sane solution will be something that's closer to a large water mains pipe supported by a roller coaster frame.
- Aeolun 4y ago
  A practical railgun of that kind is several kilometers long last I heard.
  - thrown_22 4y ago
    It has to withstand exactly the same forces as the torsion arm used here.
    - aaronblohowiak 4y ago
      That’s not true? The problem with spinning is the pulling to the outside, not the going faster. With a straight track/tube you only have the go faster forces not the pull to the outside
cjensen 4y ago
You can't fire anything into Earth orbit. Once propulsion is complete, you are in an orbit. Orbits repeat. So if your orbit starts from the ground, your orbit will intersect the ground which is... undesirable. Instead, you have to fire a rocket motor to alter the initial orbit into one that doesn't intersect the ground. Now you have a new problem: you have to design a rocket motor which can withstand the launch. A solid rocket almost certainly will spontaneously RUD when heavy acceleration is applied. A liquid rocket has pumps and pipes which are likely can't survive the acceleration. This is the reason spin launch is nonsense: you've traded a solved problem (make big rocket motor) for an unsolvable problem: make a rocket motor which can withstand absurd acceleration. The other red flag with spin launch is that genuinely new approaches to problems do not come from unqualified randos thinking about a problem. For example, if a company has a crazy new idea for blood testing, it's really bad if the crazy new idea came from someone with zero experience and zero domain knowledge.
- 01100011 4y ago
  > https://www.freethink.com/space/low-earth-orbit-satellite https://www.freethink.com/space/low-earth-orbit-satellite Seems like there is already a mechanism, sans moving parts, of generating force post-launch. Not saying it is sufficient to correct a ground-launched, ballistic projectile though. > A solid rocket almost certainly will spontaneously RUD when heavy acceleration is applied I am skeptical that there is no chemical propellant capable of resisting the initial acceleration. That seems like a bold claim. What about gas-based thrusters(i.e. ion drive with xenon or even just nitrogen gas)?
  - cjensen 4y ago
    The LEO post-launch force you link to is for minor orbital changes. Or large changes over a large amount of time. The problem with an orbit that begins at the ground is that you have exactly one orbit's worth of time in which to convert it into a real orbit. Magnetic or ion propulsion won't cut it. My comment about solid rockets is due to the fact that they include fully combustable fuel in a ready-to-use mix. Solid rockets don't require much input to get them to combust. I assume no one is considering solid rockets for this application; I only mention it as part of assuming they would need a liquid rocket so I could explain the problem with liquid rockets which rely on pumps and pipes.

TheLoafOfBread 4y ago

Even if something is rated on i.e. 1000G it is rated for a very short time, like a shock or a fall on the ground. Which from my perspective is the problem of whole concept described in the video. In 5:55 minute mark, video is describing force applied on the payload will reach from 1G to 10000G, but how long does this take? 10 minutes? 30 minutes? An hour? Can you have a payload which will be able to withstand 1000G+ for minutes? Contrary to big cannons, like [0] there would be forces of 10000G only for few milliseconds as shells are accelerating only during the time of being in the barrel. [0] https://en.wikipedia.org/wiki/Project_HARP https://en.wikipedia.org/wiki/Project_HARP

gonzo41 4y ago
I would guess you'd do something like try and cast any electrical components in something like a resin so it's just a solid brick that can handle the stresses. But 10k G is a lot.
- TheLoafOfBread 4y ago
  Well problem is that this concept is supposed to replace 1st stage as it can reach only to 70km. What kind of 2nd stage rocket engine can survive such Gs? Solid booster which you can't control?
  - chasil 4y ago
    There is lengthy discussion at the end of the video on design changes, primarily for the reaction wheel. They conclude by placing a digital camera in their lab mockup and taking it to 10,000g. This probably would not have worked for a phone, but they seem quite confident.
  - adgjlsfhk1 4y ago
    They have the significant advantage that they get pretty much free mass before the fairing opens (since more mass reduces drag and they aren't fighting the rocket equation until they are out of the atmosphere). As such they can do things like heavily brace the inside of the nozzle without it hurting their payload capacity.
- MichaelCollins 4y ago
  10k G should be doable, during WW2 the allies had radio proximity fuzes for artillery shells that exceeded that: https://en.wikipedia.org/wiki/Proximity_fuze https://en.wikipedia.org/wiki/Proximity_fuze
  - TheLoafOfBread 4y ago
    What about the rest of the satellite? Solar panels, antenna, engines?
    - MichaelCollins 4y ago
      It all seems generally dubious to me. But I think solar panels could survive that force if they were firmly supported inside the vehicle before launch; I don't think the acceleration itself would break the panels if they were prevented from flexing. For an engine, maybe solid fuel but the fuel itself would be structural. A pressure-fed liquid fuel engine might be easier, if you could get valves (and actuators for those valves) to survive that kind of force.
  - torginus 4y ago
    The problem is that this thing is supposed to throw a whole second stage rocket, with plumbing, turbopumps with moving parts, and fuel that sloshes around.
    - JumpCrisscross 4y ago
      > fuel that sloshes around Pressure and ballast balls.
  - morcheeba 4y ago
    That was one design that was extensively tested and then copied. Weight was no concern. Most satellites are unique, so the same can't be done. Besides being weight critical, every failed satellite becomes space junk.
    - 4y ago
- Animats 4y ago
  Militaries have been shooting working electronics out of guns since WWII. The earliest versions were vacuum tube proximity fuses. The U.S, military has been shooting guided weapons out of guns since the 1970s. They work pretty well. This technology seems to be suited for launching moderate numbers of small satellites. It's not a huge win on launch cost over filling up a Falcon 9 with racks of small satellites. This competes with the Pegasus air-launch system, where a rocket is carried to high altitude by an aircraft. That works fine, and launches have been going on since the 1990s. But it's not a huge financial win. It's good to have a few competing technologies. Keeps the price down.
Someone 4y ago
One advantage this has over guns is that jerk (https://en.wikipedia.org/wiki/Jerk_(physics) https://en.wikipedia.org/wiki/Jerk_(physics)) is lower. I don’t know whether it makes a difference in survivability, but it seems to me that it would, at least somewhat, for some materials. But then, what do I know? Impact resistance typically is reported in gs, but that might be a simplification because, typically, the higher order time derivatives of position correlate well with acceleration.
- JKCalhoun 4y ago
  I would invest in more rockoon research. More of an elegant way to sidestep the thick atmosphere we're straddled with rather than brute force it with cannons and such. https://en.wikipedia.org/wiki/Rockoon https://en.wikipedia.org/wiki/Rockoon
  - aaronblohowiak 4y ago
    Makes a lot of sense to me — make the atmosphere do a lot of the heavy lifting rather than fuel.
bergenty 4y ago
The rate of change of acceleration is going to be massive in a cannon though. That intuitively feels worse than very high acceleration but with a more gradual increase in the rate of change.

thrown_22 4y ago

Or a closed magnetic rail which you unlatch when you fire. The idea that you should use an actual spinning arm is needed is what everyone has a problem with. A sane solution will be something that's closer to a large water mains pipe supported by a roller coaster frame.

Aeolun 4y ago
A practical railgun of that kind is several kilometers long last I heard.
- thrown_22 4y ago
  It has to withstand exactly the same forces as the torsion arm used here.
  - aaronblohowiak 4y ago
    That’s not true? The problem with spinning is the pulling to the outside, not the going faster. With a straight track/tube you only have the go faster forces not the pull to the outside

cjensen 4y ago

You can't fire anything into Earth orbit. Once propulsion is complete, you are in an orbit. Orbits repeat. So if your orbit starts from the ground, your orbit will intersect the ground which is... undesirable. Instead, you have to fire a rocket motor to alter the initial orbit into one that doesn't intersect the ground. Now you have a new problem: you have to design a rocket motor which can withstand the launch. A solid rocket almost certainly will spontaneously RUD when heavy acceleration is applied. A liquid rocket has pumps and pipes which are likely can't survive the acceleration. This is the reason spin launch is nonsense: you've traded a solved problem (make big rocket motor) for an unsolvable problem: make a rocket motor which can withstand absurd acceleration. The other red flag with spin launch is that genuinely new approaches to problems do not come from unqualified randos thinking about a problem. For example, if a company has a crazy new idea for blood testing, it's really bad if the crazy new idea came from someone with zero experience and zero domain knowledge.

01100011 4y ago
> https://www.freethink.com/space/low-earth-orbit-satellite https://www.freethink.com/space/low-earth-orbit-satellite Seems like there is already a mechanism, sans moving parts, of generating force post-launch. Not saying it is sufficient to correct a ground-launched, ballistic projectile though. > A solid rocket almost certainly will spontaneously RUD when heavy acceleration is applied I am skeptical that there is no chemical propellant capable of resisting the initial acceleration. That seems like a bold claim. What about gas-based thrusters(i.e. ion drive with xenon or even just nitrogen gas)?
- cjensen 4y ago
  The LEO post-launch force you link to is for minor orbital changes. Or large changes over a large amount of time. The problem with an orbit that begins at the ground is that you have exactly one orbit's worth of time in which to convert it into a real orbit. Magnetic or ion propulsion won't cut it. My comment about solid rockets is due to the fact that they include fully combustable fuel in a ready-to-use mix. Solid rockets don't require much input to get them to combust. I assume no one is considering solid rockets for this application; I only mention it as part of assuming they would need a liquid rocket so I could explain the problem with liquid rockets which rely on pumps and pipes.