Hi Hilmar,
>I find the entire article doubtful. What makes it extremely doubtful IMO is that even a partial gravitational shielding would violate the principle of Conservation of Energy.

if it is only "doubtful", we should take the chance and apply for a patent on a gravitic engine. Something like a backwards 2 stroke combustion engine: compressing will be done by a falling weight which is also tapped for energy, while lifting on the other stroke is done by shielding gravitiy of the weight and giving it a small nudge from the previously compressed air. Perpetuum mobile as soon as the energy generated by the "downward" movement is greater than the energy needed for the "gravity shield". And it is not even friday...

regards

thomas