conclusions on trimming and decalage
the data that i have found the most precise on the issue was mentioned by mikeruth in his post 3919 of the forum of the radian:
https://www.rcgroups.com/forums/show....php?t=2089760
he said: Page 20 of this article is a very good explanation of Setting decalage and CG.
I have been using this for years.
http://www.rcsoaringdigest.com/pdfs/...SD-1992-03.pdf
the article was re-issued on 1992, and the copyright by Frank Deis is from 1990. it is the oldest i have ever seen on the subject, so the credit goes to him, and the flight test goes as far as 1973.
(by the way, the drawing has a mistake: in the rectangle at the left it says that cg is too far "forward" but should be "aft").
it shows how to do it and also shows tests on fixed stab and moving stabilator.
i will make a condensation of all that matters in that article. the goal is to have a decalage of about 1 to 3 degrees.
(decalage is the angular difference between the wing airfoil and the stabilizer).
this is the way i interpret it:
1.-start with a 33% balance point (called center of gravity);
test fly the plane:
2.-for a fixed stab (with moving elevator), trim the elevator until the plane glides well:
if the elevator is not parallel to the fixed stab, move the cg accordingly:
a.-if the elevator is up, move the cg back a little and try again until the elevator is parallel to the stab.
b.-if the elevator is down, move
...Continue Reading