I'm in the same boat, trying to come up with a good power package for a Riser 100. Using MotoCalc, I got a long list of motor and prop combinations, and it seems all are very expensive. This is my first real shot at powered soaring, and I don't want to sink a bunch of money in it, so I did a lot of digging, and found that what was most recommended is 70-80 watts per pound for this type of aircraft. I also read that a bigger, slower turning prop will do better. So after doing a bit of shopping, I came up with a Turnigy G15 710kv motor, and I already have 11 x 7 and 12 x 7 Graupner folding props to go on it. The motor may a bit of overkill, but the price is certainly more affordable. Does this sound like I'm in the ballpark Mr. Matthews?