Calculate Force Required to Hover (Rigid Body)

Questions & Answers
1

Is it possible to calculate the exact force required to keep a rigid body hovering in the air with gravity on and taking into account the bodies mass etc. This force will be applied along the Y axis.

I wish to make my craft hover perfectly and want to be able to dynamically change the weight etc.

2

Taken from unity tutorials:

if (Physics.Raycast(ray, out hit, hoverHeight))
        {
            float proportionalHeight = (hoverHeight - hit.distance) / hoverHeight;
            Vector3 appliedHoverForce = Vector3.up * proportionalHeight * hoverForce;
            carRigidbody.AddForce(appliedHoverForce, ForceMode.Acceleration);
        }

That will basically try to maintain a hoverHeight.

You can do the full tutorial here: Unity Connect