On the first page of the chapter on Weight Distribution, Lennon makes a couple of errors":
The PU's [power unit's] weight multiplied by its distance from the model's CG is its "moment of inertia".
It is the square of the distance, because for a given rotation rate the mass moves faster if farther from the CG and it also resists change in rotation with a longer lever arm. He does mention "Also longer moment arms...." but it is not clear that this is to be multiplied, and anyway angular moment of inertia is defined with the square in it. This is important, among other things, because the square is what makes a smaller vehicle more maneuverable than a larger one. (Actually, the moment of inertia is a tensor, but he was right not to confuse people with that. That is, the angular momentum is not always parallel to the rotation axis.)
The other error is that he says that a model with greater angular inertia will do a wider loop. Starting and stopping the loop will take longer, but during the round part of the loop the rate of rotation is not changing significantly, so the moment of inertia makes little difference.