Wings

I am installing the AFS AoA system. It is quite important to me since as I have mentioned elsewhere I fly in and out of a very short strip. It comprises two pressure sensors, one on the top of the wing and one on the bottom, together with a processor and display. The sensors need to be placed reasonably precisely, and surprisingly to me, are located in the final outboard bay of the RV4 wing. It makes for an easy installation. My surprise stems from the fact that the airflow at the tip can not be representative of the wing as a whole.

With the kit there is a #60 drill bit to drill the hole in the wing surface through which the pressure is sensed.

In this picture the sensors are not yet sealed in place. I will probably use proseal. The upper sensor has a sump with a drain valve in case water is sucked in. It seems unlikely through a #60 hole, though I suppose a descent in heavy rain might just force it in. I am told it very rarely does. On the ground you can operate the drain valve by means of a steel probe (supplied with the kit) through a hole you can just see in the top left hand corner of the picture, the bottom surface of the wing. To my surprise it is easy to find the drain valve with the rod without looking.

There is a nice touch with the kit. They suggest you use the blue tube (nearer the sky) for the upper sensor, and the green tube (grass) for the lower surface one.

Yes, I do jump around a bit in my work. I'll get back to the tips soon. Right now I am waiting on some welding.

I have started on the left wing tip. Its well made, much better than the tips I received when I built an RV-9A. So far I have cut out a foam former which I have pressed inside the glass tip and pushed it onto the wing. I then used one of those straps (blue) with a ratchet to push the tip down to the leading edge. Without much pressure it pushed it about 1/8th inch forward against the leading edge. I am planning to make the tips removable with #6 screws and tinnerman washers at 2.5" spacing. For now I have marked out the hole locations and drilled every 3rd one with a #40 drill.












So far so good! I am worrying that I should have first locked the aileron in position to ensure alignment. I think I will do that next to be sure, though they are so stiff once mounted without attachment, that I doubt there will be much I can do to move where the trailing edge of the tip wants to sit. Lets hope it is in the right place!

I would strongly recommend having a foam mat on the floor when you are trying to get the tips on because they have a will of their own not wanting to go inside the wing.