With sub-stepping on async physics calculations the two tick events are unhooked from each other and all go at the same rate.
You could try capturing the sim seconds and check via a modulo (modulus in ue) operator if a compared to a value it’s equal zero (example sim time mod 2 == 0) and then add the force with a bool that makes it happen once per occurrence. Then you could steadily add the force every two seconds no matter the tick. (OFC 2 seconds is just an example experiment until you are happy with the result)
It wil be a steady stream of force then.
Ok so direct modulus comparison can be too precise with the fluctuations in sim time (causing lack of execution in some cases). Better use nearly equal to get a more reliable result.
Think of it as a controlled burn in a rocket, with spurts of fuel.
You’ll have to play around with the modulo percentage and nearly equal value to get it stable.
Or you could consider Add Impulse in place of Add Force