i have done some maths.
R.A.T.T works I90 rocket, modified
overall tank volume = around 720cc
weight of the 2 tanks = 2.48kg full
i need around 800g of fuel for 12 second burn
the rocket alone will weigh around 3.5kg
average thrust will be around 7.5kg
max thrust will be around 17kg
hear is the throttle curve for an un-modified one
i dont know if i will choose this combination at the moment and correct me if i have made a mistake.