Airplane will not trim
#26
Thread Starter

After a few weekends, and much head scratching, have found at least part of the problem.
The AOI was +5 deg. spec calls for -2deg add to that the rear stab was found to be around -.5.
I am going to shim the wing and see what happens I suspect it will fly a lot better.
I suspected this was an issue but without a meter was just guessing. And where the other plane flew so well set up in a similar fashion there had to be something way out of wack.
Thanks for all your input.
The AOI was +5 deg. spec calls for -2deg add to that the rear stab was found to be around -.5.
I am going to shim the wing and see what happens I suspect it will fly a lot better.
I suspected this was an issue but without a meter was just guessing. And where the other plane flew so well set up in a similar fashion there had to be something way out of wack.
Thanks for all your input.
#27
The angular difference between the wing and tail is commonly reffered to as the decalage angle. 10 degrees is CRAZY high and totally explains the flight charactaristics you encountered. Shim the wing and shim the tail and keep in mind the engine thrust angle. Get it into spec whatever you need to do. The fuselage center line means diddly. It's the angle of the thrust line, the wing and the tail surfaces that counts. The centerline is just a convienient way to provide a basis to compare them.
I doubt if just shimming the wing will do the total trick. It'll certainly make it better but if that -5 degree angle of the stab isn't proper then you'll still have a big problem.
I doubt if just shimming the wing will do the total trick. It'll certainly make it better but if that -5 degree angle of the stab isn't proper then you'll still have a big problem.
#28
Thread Starter

Bruce,
Thanks will do...
I should have typed -0.5 deg for the stab. just .5 gets lost, it wasn't that bad but the AOI is way out anyhow. Hopefully setting the wing at -2 from the + 5 should help.
If not I may be posting what the VNE is for this aircraft. LOL
I think I may take out some of the right thrust, I have not measured it yet but this is the first airplane I have ever used left rudder on takeoff...
Thanks will do...
I should have typed -0.5 deg for the stab. just .5 gets lost, it wasn't that bad but the AOI is way out anyhow. Hopefully setting the wing at -2 from the + 5 should help.
If not I may be posting what the VNE is for this aircraft. LOL
I think I may take out some of the right thrust, I have not measured it yet but this is the first airplane I have ever used left rudder on takeoff...
#29
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Joined: Nov 2004
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From: Mission Viejo,
CA
Remember to take out all or most of the elevator down trim before the first test flight. Possibly move CG closer to where it is supposed to be. That is a big change that is will hopefully improve control.
#30
Senior Member
Don't bother with trying to change the tail incidence --- that should be your reference -- adjust the wing incidence & thrust line appropriately.




