chris mitchell
Well Known Member
This post is a bit long and a bit complex - I've tried hard to explain where I have got to so I hope its not confusing! I'm feeling uncertain about how to proceed, so please read on and give me the benefit of the accumulated VAF experience!
I spent the weekend rigging the ailerons and flaps. Previously, when building the wings, I had set the aileron pushrod length with the aileron locked in the neutral position and the bellcrank also locked. For the former I used an aluminum strip appropriately drilled and attached to the tool holes in the outermost rib, with a bolt through it that sat tightly in the trailing edge radius of the aileron. For the latter I used the Vans template. So far so good.
Now that the wings are on, I mounted the ailerons and flaps, again set the ailerons in the neutral position and set the bellcrank. I attached the flaps (after trimming the upper surface to match the fuselage) and the flap pushrods (after enlarging the holes that the pushrods run through. Then, before drilling any holes for the flap fairings, I thought I would check that the ailerons and flaps on the left sat at the same angle as the ailerons and flaps on the right.
Leveled fuselage along and across top longerons, rechecked incidence and both wings are at identical incidence within 0.1 of a degree (using a digital angle meter). I then put the meter on the top surface of the outboard part of the right aileron - 10.6 degrees, and inboard 10.8 degrees. The right flap not surprisingly as I had aligned its trailing edge with that of the adjacent aileron - was 10.8 degrees. On the left side the outboard aileron measurement was 10.3, inboard 10.2 and the flap 10.2 degrees ie all slightly less than the right.
Taken at face value, the implications of these measurements to me are that:
In flight the aircraft will try to roll to the left (right aileron down in comparison to left average 10.7 versus 10.15 ie 0.55 degrees different)
The left aileron has a slight twist (0.1)
The right aileron has slightly more twist (0.2)
Given the uncertainties in any measurement process - even the leveling process is subject to + or - 0.1 degree (smallest calibration on the meter), then all the individual measurements also; and the inaccuracies of building a handmade aircraft, - are these figures acceptable? Has anyone else gone through this exercise (surely you all have?). My inclination is to go back and adjust and tweak until everything is as identical as I can make it - after all I got the wings to come out as identically as I can measure. But in practice would I notice the control stick deflection need to take out these minute differences? If I toured the hangar checking all the production aircraft, would they even come close to these sorts of differences?
As ever, many thanks in advance.
Chris
RV8, final assembly......
I spent the weekend rigging the ailerons and flaps. Previously, when building the wings, I had set the aileron pushrod length with the aileron locked in the neutral position and the bellcrank also locked. For the former I used an aluminum strip appropriately drilled and attached to the tool holes in the outermost rib, with a bolt through it that sat tightly in the trailing edge radius of the aileron. For the latter I used the Vans template. So far so good.
Now that the wings are on, I mounted the ailerons and flaps, again set the ailerons in the neutral position and set the bellcrank. I attached the flaps (after trimming the upper surface to match the fuselage) and the flap pushrods (after enlarging the holes that the pushrods run through. Then, before drilling any holes for the flap fairings, I thought I would check that the ailerons and flaps on the left sat at the same angle as the ailerons and flaps on the right.
Leveled fuselage along and across top longerons, rechecked incidence and both wings are at identical incidence within 0.1 of a degree (using a digital angle meter). I then put the meter on the top surface of the outboard part of the right aileron - 10.6 degrees, and inboard 10.8 degrees. The right flap not surprisingly as I had aligned its trailing edge with that of the adjacent aileron - was 10.8 degrees. On the left side the outboard aileron measurement was 10.3, inboard 10.2 and the flap 10.2 degrees ie all slightly less than the right.
Taken at face value, the implications of these measurements to me are that:
In flight the aircraft will try to roll to the left (right aileron down in comparison to left average 10.7 versus 10.15 ie 0.55 degrees different)
The left aileron has a slight twist (0.1)
The right aileron has slightly more twist (0.2)
Given the uncertainties in any measurement process - even the leveling process is subject to + or - 0.1 degree (smallest calibration on the meter), then all the individual measurements also; and the inaccuracies of building a handmade aircraft, - are these figures acceptable? Has anyone else gone through this exercise (surely you all have?). My inclination is to go back and adjust and tweak until everything is as identical as I can make it - after all I got the wings to come out as identically as I can measure. But in practice would I notice the control stick deflection need to take out these minute differences? If I toured the hangar checking all the production aircraft, would they even come close to these sorts of differences?
As ever, many thanks in advance.
Chris
RV8, final assembly......