With an all up weight under 7lb and a wing loading of just 8.4oz/sq ft, this model was never going to be a racing machine. However, since I'm flying it off the slope, a certain amount of penetration is necessary to enable the model to be flown in windier conditions than were perhaps envisaged when Gordon Waite designed it as a thermal soarer. So I decided that the option of adding a bit of lead might come in handy.
Clearly, the ballast needs to go as close to the cg as possible. Similar logic was of course applied to the design of the full size machine to ensure that variability in the weight of the pilot doesn't upset the handling so the best place for the ballast is in the area of the pilot's seat.
Had I thought about this earlier, I might have made the seat a more substantial (and easily removable) structure so that ballast could be attached directly to it. However, that's not practicable with the current seat and, rather than re-make it, I decided to try to work out a method of fitting ballast under the seat, from behind the wing mounting bulkhead.