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This would be used in something like Starraker. That design can get 100 tons to orbit with a single stage much more efficiently than any rocket. Take off like a

This would be used in something like Starraker. That design can get 100 tons to orbit with a single stage much more efficiently than any rocket. Take off like a plane, climb to high altitude. Enter a supersonic dive. Pull up and ignite your rockets from high in the atmosphere when travelling relatively fast. You need much less fuel that way. The wings get you the first 30k mètres.

rjmunro 3y ago
Orbit is not about height, it is about speed. You have to get to almost 30km/s otherwise you aren't in orbit and you fall back into the atmosphere.
- 3m 3y ago
  I think you are confusing the speed at which the earth orbits the sun (~29.8km/s) with the speed at which an object needs to travel to maintain earth orbit (~7.8km/s).
  - rjmunro 3y ago
    Whoops, you are right. I think it's too late to edit my original post. The point still stands, though, you have to get to nearly 8km/s otherwise you aren't in orbit and you fall back into the atmosphere. You can't get to anywhere near that speed while still in the atmosphere - SR-71s only manage about 1km/s, and because kinetic energy is proportional to the square of the speed, at that point you are only 1/64th of the way there.
- seabass-labrax 3y ago
  To get to an appropriate speed, you need to accelerate eventually. But it's easier to do that at a higher altitude, where you have thinner air to travel through: less drag, less severe transonic effects to mitigate and, on the way up, a wider variety of air-breathing engine types to choose from (including the Astro Mechanica one).
  - pfdietz 3y ago
    The wider variety of air-breathing engines points out a problem: the launcher necessarily goes through a wide variety of aerodynamic regimes where different engines work. Making a single engine that works over a wide range of speeds is difficult. And for what? Using more fuel in a larger first stage just so you can save on cheap oxidizer (LOX at $.10/lb)?
pfdietz 3y ago
> with a single stage SSTO is driven by the notion that staging is dangerous and worth avoiding. I think the SpaceX experience shows that effort was better spent making staging reliable rather than trying to make SSTO work.
- Kim_Bruning 3y ago
  Eh, winged SSTO has some very practical potential advantages! (To wit: you can use existing airfields for your turnaround). This is not me advocating for winged SSTO every day of the week. But I can definitely see the lure.
  - wolfram74 3y ago
    Are those advantages worth inherently worse amortization costs on the first stage though? A TSTO can have one first stage for ~10ish orbiters since it's only used for 10 minutes while the orbiter has to do all it's supposed to do before coming back into the soup. An SSTO definitionally has to have all parts of the vehicle involved at all stages of operation. I think a more complicated ground facility is fine if you're doing enough flights.
    - JumpCrisscross 3y ago
      > Are those advantages worth inherently worse amortization costs on the first stage If you can launch from and land at any airfield, even if just any military airfield, absolutely. You've opened the market for point-to-point ballistic transport.
      - consumer451 3y ago
        > point-to-point ballistic transport. What does ICBM early warning look like in a world with point-to-point ballistic transport?
        dotancohen 3y ago
jve 3y ago
Orbit is a different beast than space. > The extra energy needed to make an object travel fast enough to stay in orbit is more than 30 times as much as the energy needed to lift it to an altitude of 100 km. https://www.sciencelearn.org.nz/resources/272-launching-satellites https://www.sciencelearn.org.nz/resources/272-launching-sate...

rjmunro 3y ago

Orbit is not about height, it is about speed. You have to get to almost 30km/s otherwise you aren't in orbit and you fall back into the atmosphere.

3m 3y ago
I think you are confusing the speed at which the earth orbits the sun (~29.8km/s) with the speed at which an object needs to travel to maintain earth orbit (~7.8km/s).
- rjmunro 3y ago
  Whoops, you are right. I think it's too late to edit my original post. The point still stands, though, you have to get to nearly 8km/s otherwise you aren't in orbit and you fall back into the atmosphere. You can't get to anywhere near that speed while still in the atmosphere - SR-71s only manage about 1km/s, and because kinetic energy is proportional to the square of the speed, at that point you are only 1/64th of the way there.
seabass-labrax 3y ago
To get to an appropriate speed, you need to accelerate eventually. But it's easier to do that at a higher altitude, where you have thinner air to travel through: less drag, less severe transonic effects to mitigate and, on the way up, a wider variety of air-breathing engine types to choose from (including the Astro Mechanica one).
- pfdietz 3y ago
  The wider variety of air-breathing engines points out a problem: the launcher necessarily goes through a wide variety of aerodynamic regimes where different engines work. Making a single engine that works over a wide range of speeds is difficult. And for what? Using more fuel in a larger first stage just so you can save on cheap oxidizer (LOX at $.10/lb)?

pfdietz 3y ago

> with a single stage SSTO is driven by the notion that staging is dangerous and worth avoiding. I think the SpaceX experience shows that effort was better spent making staging reliable rather than trying to make SSTO work.

Kim_Bruning 3y ago
Eh, winged SSTO has some very practical potential advantages! (To wit: you can use existing airfields for your turnaround). This is not me advocating for winged SSTO every day of the week. But I can definitely see the lure.
- wolfram74 3y ago
  Are those advantages worth inherently worse amortization costs on the first stage though? A TSTO can have one first stage for ~10ish orbiters since it's only used for 10 minutes while the orbiter has to do all it's supposed to do before coming back into the soup. An SSTO definitionally has to have all parts of the vehicle involved at all stages of operation. I think a more complicated ground facility is fine if you're doing enough flights.
  - JumpCrisscross 3y ago
    > Are those advantages worth inherently worse amortization costs on the first stage If you can launch from and land at any airfield, even if just any military airfield, absolutely. You've opened the market for point-to-point ballistic transport.
    - consumer451 3y ago
      > point-to-point ballistic transport. What does ICBM early warning look like in a world with point-to-point ballistic transport?
      - dotancohen 3y ago

jve 3y ago

Orbit is a different beast than space. > The extra energy needed to make an object travel fast enough to stay in orbit is more than 30 times as much as the energy needed to lift it to an altitude of 100 km. https://www.sciencelearn.org.nz/resources/272-launching-satellites https://www.sciencelearn.org.nz/resources/272-launching-sate...