Friday, January 19, 2007
Fitting the Wings
The RV4 build manual gives you remarkably little help in installing the wings. Disappointing, since its quite important!
Although VANS seem reluctant to tell you about it, they do have a most useful document hidden away, but available if you know where to look. A fellow builder told me, not VANS. I could easily have missed it.
There is an important difference between the two documents. The build manual stresses that you must set up the wing incidence wrt the canopy rails. The alternate document sets the wing incidence wrt the HS only, and concerns itself more with optimum fit of the fuse/flap interface.
This is important, because for me, since if I had to set the incidence wrt the canopy rails, my edge distance would have been dangerously marginal. Since I have used the 'other' document I have the fuselage about 1 degree tail high with respect to the normal canopy rail position.
You can find the VANS document here.
In these pictures, the wing incidence is set, the rear spar is drilled, under size at the moment, and its now time to do a trial fit of the flaps. Depending on just how the flaps sit, I still have a last opportunity to raise or lower the trailing edge a little since the hole is under size. I still have to hold on to the 5/8" edge distance.
I don't know why, but as you can see from the pictures, the right hand wing sits very slightly lower than the left. Still that is not what is important. Its identical wing incidence that matters.
If I wanted to do a trial fit of the flap, I had to be able to get the flap hinge in and out. No methodology for this is given in the build manual, so I plagiarised a German solution, and drilled a hole in the aileron bearing bracket, so the hinge can be withdrawn through the bracket. I haven't quite decided how to stop the hinge working its way out, but I have several ideas.
This is where I have to get to in order to do an initial setup. To decide where the flap should sit you need the aileron installed, though not in this position.
This shows the detail fitting of the flap. The upper skin has to be cut
to fit around the fuselage. The lower skin tucks underneath.
Although VANS seem reluctant to tell you about it, they do have a most useful document hidden away, but available if you know where to look. A fellow builder told me, not VANS. I could easily have missed it.
There is an important difference between the two documents. The build manual stresses that you must set up the wing incidence wrt the canopy rails. The alternate document sets the wing incidence wrt the HS only, and concerns itself more with optimum fit of the fuse/flap interface.
This is important, because for me, since if I had to set the incidence wrt the canopy rails, my edge distance would have been dangerously marginal. Since I have used the 'other' document I have the fuselage about 1 degree tail high with respect to the normal canopy rail position.
You can find the VANS document here.
In these pictures, the wing incidence is set, the rear spar is drilled, under size at the moment, and its now time to do a trial fit of the flaps. Depending on just how the flaps sit, I still have a last opportunity to raise or lower the trailing edge a little since the hole is under size. I still have to hold on to the 5/8" edge distance.I don't know why, but as you can see from the pictures, the right hand wing sits very slightly lower than the left. Still that is not what is important. Its identical wing incidence that matters.
If I wanted to do a trial fit of the flap, I had to be able to get the flap hinge in and out. No methodology for this is given in the build manual, so I plagiarised a German solution, and drilled a hole in the aileron bearing bracket, so the hinge can be withdrawn through the bracket. I haven't quite decided how to stop the hinge working its way out, but I have several ideas.
This is where I have to get to in order to do an initial setup. To decide where the flap should sit you need the aileron installed, though not in this position.
This shows the detail fitting of the flap. The upper skin has to be cutto fit around the fuselage. The lower skin tucks underneath.
Labels: wings flaps
