Originally posted by mikehannah
Gents
..what you are telling me is that if I build a modern pattern design ( which I am currently doing) it should require no engine offset other than that already built in.
For your info I am currently building a MK Skystar which was built for a YS90 but I am putting a Webra 80 long stroke into it.
Mike
Well yes and then again no.
A good well sorted design sould have all the trust angles built/designed in. This depends on just how many hours the producer/designer invested in testing. With a company link MK you are pretty well sure that you're getting something worth while.
But think about this... It was as you say, designed around a YS .91. Thats what the designer used probably with a 14x10/12 APC prop etc etc...and he was happy! Now when you come along with a Webra .80 long stroke, quite a different kind of engine/power delivery I wouldn't expect it to match 100%. You'll very likely have to do a little tweeking here and there. Thats got to be excepted. Again, prop choice can make a great difference. I have a YS.91 powered G-Trick. 14x12 it tracks left. 14x8 it tracks right, 14x10, spot on.
Different designs have diffent ammounts. I have one 2x2 with 1deg down and 1.5 deg right and another 2x2 (with the same wing and stab) that has 1.5deg down and 3.5deg right. Hummmmmm. It goes without saying the former (the expensive design) flys far better then the latter(the cheap design).
By the way, with regards to the original post, if you have no down and right thrust, no wonder its going all over the place. Make the corrections PatternFlyer suggested.