Angle of Attack Pro – AoA
I agonized for ages over the prospect of installing the AoA, since I didn't think the instructions were quite as clear as I would have liked.
Here's how I did it:-
- I did the upper pressure port first. Using a sharpie pen I drew a line down the of the outboard bay from the leading edge to the aft edge. I then marked a point 6" forward from the aft edge at the edge of the skin and the center line that I had drawn and drew a line across. Finally I marked where the center of the pressure port would be, which is 4.75" from the edge of skin of the outboard bay. (These figures came out of the manual in the appendix, and I verified them against the AoA website; I'd advise you to check yourself though, just in case I screwed up!).
- Now that I had my center point for the pressure port I put a piece of masking tape on the outside of the skin. I could see the pen marks under the tape, but I re-marked the center point and the horizontal line on top of the tape to make it clearer. I placed the pressure port over that center point and then marked through one of the screw holes with a drill bit; just enough to mark the tape. Then I removed the port and drilled the hole #41. I then cleco'd the port back in place using a cleco from inside the bay: the cleco doesn't go all the way through but it does expand to grip the screw hole ok. Using the same method (drill bit through the hole) I marked and drilled the other screw hole #41. Finally, I drilled the center hole #60 (which was supplied in the AoA kit, despite what I wrote in my kitlog and what's written on the photo! I didn't use a #53
- Next job I deburred the holes and then used the DRDT-2 to dimple the screw holes for a #4 screw (I have a set of #4 dimple dies, but I think 3/32" dimples would work out ok too, screw seems to sit a little higher though, in my opinion). Since the leading edge was off the wing at this stage it was easy to do this way, but if it was on the wing you could always use a pop-rivet dimple set (Avery sells them).
- Next, I marked the underside of the wing and fitted the lower pressure port in exactly the same way. This time the port is positioned at the same 6" in front of the aft edge, but 7.5" from the outboard edge of the skin (see
- That's all that needs to be done. The next job would be to apply proseal to the white delrin parts to seal them against the wing skin and then just install the screws and allow to set. They won't come off again!
- However, I wanted to be able to easily find the water drain with that piece of wire so I decided to make a guide for it. I had a friend make up another 'port' the same dimensions as the upper port. Same mounting holes and everything. To determine where to place it I taped a 6" ruler to the upper port and then marked the lower inside skin where the ruler touched it. That gave me the rough location. When I actually came to install it, I simply assembled the upper port and the guide with a piece of 0.5" clear vinyl tube and then drilled through one of the screw holes with a right-angle drill attachment. Cleco'd it and then drilled the other screw hole. Cleco'd that, removed the vinyl tube and drilled the center hole. To give sufficient clearance for the wire I drilled out the middle hole to #27. I also countersunk the underside and the top of the guide piece that I had had made up with a larger drill so there was plenty of opportunity for water to run out of there!
- And then I did 'step 5' with all three bits. Applied proseal and then screwed them in place. The proseal alone holds the part in place while you get the screws in. I got the nuts on with needle nose pliers and then used a screwdriver to tighten the screw while holding the nut in the pliers. Don't apply too much proseal, and try to keep it away from the middle so it doesn't block anything up; that #60 hole is mighty small :-)
Here’s a link to a bunch of photos.