Woopert's RSS Replicas - SLS Blocks I and II, Saturn V

[Woopert]

still tuned old boy

I'll try to fix it up for 0.25 this weekend.

Can I make a question? How`s the core stage TWR?

In my case, I made a replica of SLS block 2, but when I detach SRB, core stage TWR drops to 0.8 so it seems unable to do circularize.

TWR after booster separation I believe is under 1.00, but the SRB's (or possibly LRB's for Block II) give enough time to apogee that you can fly a bit with a low TWR. Try to get time to apogee to 2.00 minutes at time of booster separation. That will give you time for your core stage to burn fuel and become lighter. Most real rockets have TWR's of less than 1 on their upper stages but it works out okay since they're already going fast enough.