I recently bought an Utter Chaos kit on RCU ands thought I could modify it to use an OS .91 Four stroke for SPA contests. . I spliced the fuse in several locations and widened the fuse 1/2 inch to accomodate the engine. I had to lengthen the fuse to compensate for the extra engine weight. You will notice I also placed the elevator and rudder servos in the rear fuse to counter this weight. I has worked out well. Todays' test flights went well and I like the way the plane flies. I need to move the battery aft slightly to compensate for slight nose heaviness that is still there. Throughout the construction process I continually did c/g checks to make sure I was going to come out OK. Here are the pix from todays test flights ( 7/05/07 )