@TobiasVdb The F9 booster can reach low orbit as a single stage if not carrying the upper stage and a heavy satellite.

Here is a simulation of the Falcon 9 first stage as a SSTO (Single Stage To Orbit) vehicle. There would be no practical reason for SpaceX to demonstrate this. However, I wanted to confirm the speculation that it could at least be theoretically possible. I try to keep the stress load on the rocket under 4.5Gs at all times by shutting down pairs of symmetric engines. This is a pretty aggressive flight profile, but I'm having trouble finding anything else that works. This barely makes it to LEO with a final orbit of around 180km x 170km.

The simulation software I wrote can be found on GitHub here:
https://github.com/zlynn1990/SpaceSim

If you just want to run the simulation here is a link to the program:
https://github.com/zlynn1990/SpaceSim/raw/master/builds/SpaceSim%20F9%20SSTO.zip