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My intuition, as a rocket scientist[1]. Once the boosters have come off, it feels like the drag from the nose is going to flip the rocket around. Those contro

My intuition, as a rocket scientist[1]. Once the boosters have come off, it feels like the drag from the nose is going to flip the rocket around. Those control surfaces on the nose are at the exact wrong end of the rocket. They don’t even need to be dynamic — a set of static stabilizers at the rear of the liquid stage is should be added to provide stabilizing drag after the boosters have been detached. This might not be a problem if the rocket has reached an altitude where it is subsonic or the drag from air is small enough to be countered by the torque provided by thrust vectoring. Those engines have a gimbal, right? [1] I’ve worked at KSC[2] since almost the very beginning[3] of the programme. [2] Kerbal Space Center. [3] 0.18. ...written with apologies to those who are actually qualified in this area.

_Microft 7y ago
I think the thing at the top of the rocket is meant to be a launch escape tower. Gimballed engines should give more than enough control authority. Look how the tumbling SpaceX booster regained control after relighting one of its engines [0]. All in all my first impression of the Lego rocket was that it is far too small (or short) to get to orbit and replacing the second stage with even more payload... well, that's not even a rookie mistake. [0] https://www.youtube.com/watch?v=rkR7iaim4aw https://www.youtube.com/watch?v=rkR7iaim4aw
arijun 7y ago
Funnily enough, when I was first reading your comment, I was thinking, yeah, being a rocket scientist is great, but people who play KSP probably have better intuition about how wacky things like this would fly (as per the XKCD[1])[2]. [1] https://xkcd.com/1356/ https://xkcd.com/1356/ [2] Written as someone who does neither
- cbanek 7y ago
  As someone who's done both, I agree with the article that basically the rocket isn't big enough. Or my feeling is that the cockpit part is actually too big in relation. But it still looks like a fun kit, as someone who also loves building legos. As someone who's built the Lego Saturn V kit, that one is a lot bigger. :)
  - teknopaul 7y ago
    I think its big enough already. It took a four man team most of Christmas to assemble. The additional thrust is provided by what creationists call "the guiding hand". Mid flight power into very high orbit provided by grandads new chairlift. In a serious of unplanned aborts the SRBs proved the most resilient component. Satalite payload went the way of Galileo shortly after lunch.
sandworm101 7y ago
Looking at their nozzles, the boosters also appear to be SRBs. That's a real rookie mistake. Nobody has dared launch humans in a capsule atop SRBs. The general consensus is that, in an emergency, deploying a parachute under a hail of burning solid rocket fuel will not end well.
- NikolaeVarius 7y ago
  Is Nozzle design actually a method of determining Solid/Liquid? I know that the design depends on expected stage of flight use and things like exhaust velocity, but i didn't think just seeing a nozzle would be enough to make a determination,
  - sandworm101 7y ago
    (1) Relative size. Solid fuel is much more energy dense. In this case, if the nozzle was for liquid then its tank is so small that it would burn out very quickly. So it is likely an SRB. Note the other nozzles for the relatively wider center tank. (2) Shape. You can look to the shape of the nozzle to see which altitude it is optimized for. SRBs are generally optimized for lower altitude. (3) Throat diameter. By following the shape of the nozzle towards the tank above you can estimate the throat. SRBs have wider throats. (4) Gimble (not seen here) SRBs can be steerable but they don't 'gimble' the same as liquid engines. Their nozzles are moved rather than the whole engine (see shuttle). So any moving nozzle bits suggests an SRB. So ya, there is much to read from just the nozzle. In fact deep in the CIA there are probably some experts with magnifying glasses studying pictures of a North Korean rocket nozzle doing exactly that.
    - NikolaeVarius 7y ago
      1) I think relative size is a bit of a crapshoot. The size of the strap-ons is effectively the same size as the center core, The second stage of the core makes it look like a full sized LOX/LH2 tank because its painted orange, but it isn't. 2-3) Sure, but that is a general principal, not a sure sign its an SRB. 4) I don't see a sign of a gimbal. It may actually not even be a nozzle, and just the skirt.
NikolaeVarius 7y ago
By the time the all engines shut off, I would hope that the capsule is high enough where drag is effectively not a concern. The nose is a Apollo/Starliner style launch escape system.

_Microft 7y ago

I think the thing at the top of the rocket is meant to be a launch escape tower. Gimballed engines should give more than enough control authority. Look how the tumbling SpaceX booster regained control after relighting one of its engines [0]. All in all my first impression of the Lego rocket was that it is far too small (or short) to get to orbit and replacing the second stage with even more payload... well, that's not even a rookie mistake. [0] https://www.youtube.com/watch?v=rkR7iaim4aw https://www.youtube.com/watch?v=rkR7iaim4aw

arijun 7y ago

Funnily enough, when I was first reading your comment, I was thinking, yeah, being a rocket scientist is great, but people who play KSP probably have better intuition about how wacky things like this would fly (as per the XKCD[1])[2]. [1] https://xkcd.com/1356/ https://xkcd.com/1356/ [2] Written as someone who does neither

cbanek 7y ago
As someone who's done both, I agree with the article that basically the rocket isn't big enough. Or my feeling is that the cockpit part is actually too big in relation. But it still looks like a fun kit, as someone who also loves building legos. As someone who's built the Lego Saturn V kit, that one is a lot bigger. :)
- teknopaul 7y ago
  I think its big enough already. It took a four man team most of Christmas to assemble. The additional thrust is provided by what creationists call "the guiding hand". Mid flight power into very high orbit provided by grandads new chairlift. In a serious of unplanned aborts the SRBs proved the most resilient component. Satalite payload went the way of Galileo shortly after lunch.

sandworm101 7y ago

Looking at their nozzles, the boosters also appear to be SRBs. That's a real rookie mistake. Nobody has dared launch humans in a capsule atop SRBs. The general consensus is that, in an emergency, deploying a parachute under a hail of burning solid rocket fuel will not end well.

NikolaeVarius 7y ago
Is Nozzle design actually a method of determining Solid/Liquid? I know that the design depends on expected stage of flight use and things like exhaust velocity, but i didn't think just seeing a nozzle would be enough to make a determination,
- sandworm101 7y ago
  (1) Relative size. Solid fuel is much more energy dense. In this case, if the nozzle was for liquid then its tank is so small that it would burn out very quickly. So it is likely an SRB. Note the other nozzles for the relatively wider center tank. (2) Shape. You can look to the shape of the nozzle to see which altitude it is optimized for. SRBs are generally optimized for lower altitude. (3) Throat diameter. By following the shape of the nozzle towards the tank above you can estimate the throat. SRBs have wider throats. (4) Gimble (not seen here) SRBs can be steerable but they don't 'gimble' the same as liquid engines. Their nozzles are moved rather than the whole engine (see shuttle). So any moving nozzle bits suggests an SRB. So ya, there is much to read from just the nozzle. In fact deep in the CIA there are probably some experts with magnifying glasses studying pictures of a North Korean rocket nozzle doing exactly that.
  - NikolaeVarius 7y ago
    1) I think relative size is a bit of a crapshoot. The size of the strap-ons is effectively the same size as the center core, The second stage of the core makes it look like a full sized LOX/LH2 tank because its painted orange, but it isn't. 2-3) Sure, but that is a general principal, not a sure sign its an SRB. 4) I don't see a sign of a gimbal. It may actually not even be a nozzle, and just the skirt.

NikolaeVarius 7y ago

By the time the all engines shut off, I would hope that the capsule is high enough where drag is effectively not a concern. The nose is a Apollo/Starliner style launch escape system.