[Svartalfiar]

I see they plan to spin inside a huge vacuum chamber. That almost eliminates the bird problem, but the release must be timed with incredible precision.

They open the exit port just before releasing the rocket. Air floods in, the spin slows down slightly, then release.

Someone else posted that the ordnance will bed hitting about four revolutions per second (I did no math). If true, the doors have to be timed to fully open in less than a quarter of a second. Doors big enough for the rocket, and heavy duty enough to seal in a vacuum for the entire time it's spinning. That's a lot of movement, fast.

And, as you mentioned, the release timing. At those tangential speeds, you're probably looking at a millisecond window, if not nanoseconds. Combined with the sudden hit of air pressure (that'll be a big punch), plus the friction slow for the half-turn or so, means it's even more variable in timing. Air is going to have different densities/fill rates depending on time of day, temperature, moon/sun position (air has tides just like the ocean), wind velocity, and probably several other environmental factors. I really don't see this turning out well, for several trials at least.

[TChad]

Doors big enough for the rocket, and heavy duty enough to seal in a vacuum for the entire time it's spinning. That's a lot of movement, fast.

Might be possible with a lightweight metal (titanium?) iris door (beware of loud soundtrack):

https://www.youtube.com/watch?time_continue=5&v=wYIm5Hx82Dk&feature=emb_logo

Air is going to have different densities/fill rates depending on time of day, temperature, moon/sun position

Yes, that sounds like an unquantifiable aerodynamic mess, but the rocket is heavy and is moving much faster than the incoming wind, and most of the wind will be blowing directly at the pointed nose, so the effect on the rocket's trajectory might be minimal.

If a counterbalance to the rocket is used during spinup, something has to be done with it on launch. If the launch is parallel to the ground plane, then you might as well balance one rocket with a second rocket, launch both at once in opposite directions, then use fins/steering rockets to change the rockets' trajectories. If you launch at an angle, then the counterbalance must be slammed into the ground. Instant earthquake?

I really don't see this turning out well, for several trials at least.

One nice thing about this idea is that you can work out many of the bugs using small cheap models.

Hmm.