There's a power / height chart in the world record claim form (as well: https://dl.dropboxusercontent.com/u/5093348/Draft%20Atlas%20World%20Record%20Claim.zip

There's a power / height chart in the world record claim form (as well: https://dl.dropboxusercontent.com/u/5093348/Draft%20Atlas%20World%20Record%20Claim.zip https://dl.dropboxusercontent.com/u/5093348/Draft%20Atlas%20... More considerations are the additional power needed for control inputs and to resist wind, and to compensate for thinner air at altitude, and the weight of a craft strong anough to operate outdoors.