EastWindCC

I had the same problem before. I spent some time checking out what part was broken.I found ModularRCS provided by SSTULabs could stuck the rocket. Maybe you can check if it works.

Obviously,there's something wrong.The total △V is about 4236 m/s. I made a excel table and calculated everything related to Liquid Fuel/Oxidizer consumption.It looks like this. LV-N LV-909 engines 3.5t thrust 60kN 60kN tank 4t isp 800s 345s liquid fuel 14.4t LF 0.0076531t/s 0.0079858t/s oxidizer 17.6t OX 0 0.0097604t/s wet mass 39.5t mass 3.0t 0.5t remaining ox 8.612766t dry mass 16.112766t average isp 482.1s wet/dry 2.4514723 △V 4236m/s I got the average isp in this way: isp=dI/dm dI=F*dt and dm=m*dt, where m is propellant consumption per second. so isp=F/m then convert m/s to s You can't simply get (800+345)/2. What's more,my calculations shows the higher thrust LV-N is,the lower ΔV you'll get.