Wednesday, January 31, 2007
Rear Spar
The flaps and ailerons fit well in a trial , so it is time to drill the rear spar attach bolts out to 5/16th.
In order to achieve the 5/8th clearance I have had to force both rear spars down somewhat, but all the critical distances have been achieved.
I was delighted by a tool that another British RV builder had fabricated to aid in the drilling of the rear spar. Very ingenious. Needless to say, he was kind enough to lend it to me. Its a clamp and drill guide all in one. Its not easy to use in the cramped space, but that is because of the lack of room.
In order to achieve the 5/8th clearance I have had to force both rear spars down somewhat, but all the critical distances have been achieved.I was delighted by a tool that another British RV builder had fabricated to aid in the drilling of the rear spar. Very ingenious. Needless to say, he was kind enough to lend it to me. Its a clamp and drill guide all in one. Its not easy to use in the cramped space, but that is because of the lack of room.
It came with three brass inserts to facilitate drilling 1/8th. 3/16th and 5/16th. Here it is ready to drill the final hole.
With both holes drilled, the digital level is content that the wings are within .05 degrees of each other so I am happy.
Yes, that is my blood and DNA all over the side of the fuselage. I had bought a new drill and reamer for this step of the build, and I think just handling the reamer drew blood!
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
