4 ms·

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.

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.
  - MichaelCollins 4y ago
    If a satellite thrown by this system fails, it won't make orbit, so it won't become space junk. Even if it did make orbit; space junk in LEO isn't such a huge deal, it will fall out of the sky within a few months/years. Kessler syndrome is a popular but frequently overstated meme. With regard to weight, they say this system works best with very dense payloads. But that's only for the spin/toss stage; it doesn't account for the rocket booster needed to actually bring the satellites into orbit. As for testing, engineers don't need as much empirical testing anymore, since we have very good computer simulations now. Most of the satellites launched with this would probably be variations on a handful of designs. But I don't understand where the demand for such a launch system comes from anyway. There is only so much demand for school project cube sats; communication satellites launched this way seem dubious (not least because you can launch dozens/hundreds of them at once with a rocket like Falcon 9 or Starship)
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.

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.
- MichaelCollins 4y ago
  If a satellite thrown by this system fails, it won't make orbit, so it won't become space junk. Even if it did make orbit; space junk in LEO isn't such a huge deal, it will fall out of the sky within a few months/years. Kessler syndrome is a popular but frequently overstated meme. With regard to weight, they say this system works best with very dense payloads. But that's only for the spin/toss stage; it doesn't account for the rocket booster needed to actually bring the satellites into orbit. As for testing, engineers don't need as much empirical testing anymore, since we have very good computer simulations now. Most of the satellites launched with this would probably be variations on a handful of designs. But I don't understand where the demand for such a launch system comes from anyway. There is only so much demand for school project cube sats; communication satellites launched this way seem dubious (not least because you can launch dozens/hundreds of them at once with a rocket like Falcon 9 or Starship)

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.