For quite comfortably 1/5 of weights in a cylinder settlement vs. Earth's surface full gravity, thus having cylinder centrifugal force acceleration compared vs. Earth surface gravitational acceleration becoming 9.80/5 = .196 m/s^2 [^2 means squared], this meant having the old or new cylinder world turning once in 31.7s or 44.9s.
After all had gotten sufficiently formed, all airlocks had been closed. A little initial sent isolated oxygen + nitrogen air had been injected, to assure the cylinder shell had no air leaks. More proper good breathable air from Earth had then been introduced & warmed up by electric heaters powered from the Solar energy converting disks out on towers outside the new outer cylinder's ends.
By ion jets (using some asteroid matter also delivered here), cylinder rotation time period got slowly increased (to sqrt(2)=1.414 times that of the previous half as big cylinder settlement radius in the homes level). Seeds for the needed farms were planted. Good grass was started growing inside the park layer, plus fruit bushes, trees, etc. Grass and some fruit bushes etc. were started around the twin level homes in the layer surrounding just outside the central park level volume.
Let past settlers now move here whenever they choose. The doubled new radius 100m wants the new cylinder world to rotate in sqrt(2) times the old one's time. But no need to join the two. (Or they could be joined with maybe a temporary sliding ring link, to let them have different rotation rates.) When everyone eventually likely moves to the new cylinder, then the old one can be saved simply for letting its parts be usable for maybe forming some future more expanded bigger cylinder settlement.
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