It was the canister setup from DA. Also I did make a removable hatch on the bottom of the fuse behind the gear plate. Just remove the 1/16" sheeting and replace with 1/16 ply with cooling vents cut in it. You can even get fancy on the cooling vents if you want. I glued in a couple of 1/4 sq balsa supports along the edges so that the hatch was recessed and flush with the remaining sheeting. Used 1/4 sq basswood supports in the front and back so I could attach the hatch with small servo screws. Worked like a champ. In this pic you can see the vented hatch on the bottom.