thanks to prof hwang's expert and masterful tips, here http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2461.msg9275#msg9275

attached is the latest model that has the corrected escape velocity from Earth as -11200 m/s.

enjoy!

the new refinement is thanks to teacher feedback

"As for the simulation speed itself . . . i think this one is a bit slower? I dont recall having to wait for 3-4 minutes for the entire launch from Earth to moon, but apparently that's what is happening to the critical speeds (1.12 m/s to 1.15 m/s) Can this be addressed?"

[color=blue][b]done thanks to Prof Hwang's tips http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2461.msg9275#msg9275

also added a dt for time step[/b][/color]