Dave's got the right idea. Trig calculations (what do you do if your fuselage isn't PERFECTLY square? how much you wanna bet it ain't?) and incedence meters!! In our daddy's day do you think they were doing that stuff? And they were turning theirs loose for Free Flight! They risked it all, and managed quite well, thank you very much, by eyeballing. If you can't see a little right thrust, add some untill you do...It's like the thread about flat building boards. To listen to some folks, you just can't build on anything with .010" of bow or sag over a 4' length, can't design a proper aircraft model without CAD, and SURE can't use anything but some arcane gourd-rattling, wierd-science RIT dye method to tint your canopies... Keep it simple, and you'll get more out of it, I bet. I do.