...I ignore wing root alignment. I align the wings at either the inboard end of the ailerons or at the polyhedral break for RES models....
On a propeller blade the aerodynamic center is at the 75% radius, i.e.: 3/4 of the way out from the prop's axis to the tip of the blade. The blade angles are measured at this radius during final assembly of the prop. This is where most of the thrust is centered on the blade, so it's good for the performance issues. It's also well outboard on the blade, where most of the bending moments are generated, so it's also good for addressing vibration issues.
On a wing, we have a contradiction to deal with in this regard. For roll trim, we should measure well out on the wing, like Chuck recommends. However, the bulk of the lift on a wing is generated in the center, so for performance issues the roots are probably more critical. On the other hand, the ailerons are out near the tips, so the airfoil distortion (and related performance losses) introduced by aileron deflection is related to roll trim. This raises the priority of the outboard measurements again.
Ideally we need to consider the alignment along the entire wing. The consensus I see in all of this is that we should probably check incidences at the root, mid-span and tip, and then split the differences to get all of those as close as possible. Of course the problem with that approach is that you'll spend so much time getting the wings mounted that you'll never finish the model!
Don Stackhouse @ DJ Aerotech [EMAIL PROTECTED] http://www.djaerotech.com
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
