download the keybind boosters mod by autumnatic
then, ingame bind the keybind boosters to whatever u want (shift for example)
and then add around 7 keybind boosters to the mech anywhere (make sure they face upwards)
now hop in the mech and activate the boosters with the keybind key, now you should be flying (PS: it does flop around a lot without control sometimes, so be careful on flying into stuff)