365 hours on the hobbs - Right Elevator almost completely riveted

Took the day off yesterday and got a lot of work done on the elevator. First off, thanks Steve for pointing my incorrect reference to the rudder in my previous post - man what a slip that was.... I have changed to header to read "elevator" and not rudder.

So it started with drilling out the 4 rivets attaching the counterweight skin to the elevator skin so that I could address the missing dimples described at the end of my previous post. Then I had to carefully remove the skeleton so as not to destroy the seals I had created with the blue RTV before I clecoed everything together. This turned out to be a non-event. The RTV had hardended and held what ever shape it had been conformed to after removing the frame from the skin.

Now for some pics to explain my dilemma about the missing dimples. I had done a fair amount of research on VAF about attaching the fiberlgass tips with either screws or rivets, adn found one pots in particular with lots of good pics and explanations about what was done from Rick6A. He is a builder/mechanic with lots of experience in the industry, and tends to do his own thing and has a lot of really inventive ideas about tools and the building process. Anyway, the discussion was about using a number 4 screw vs. a number 6 screw for attaching the fiberglass. Number 8 screws are too big, and most were saying that the number 4 screws are too fragile and damage easy, and are too small in comparison with the surrounding rivets. SO the consensus was that if they could do it over again they would use a number 6 screw.

Number 6 means that it has a diameter of 6/32. That lead me to the hardware that came with my electric trim kit. During my review of the plans for the left elevator, I noted that it was using some #6 screws and K1100 nut plates to create a bracket and service pate cover for the electric elevator trim tab servo that I am using to trim the elevators. I'll get into more of a discussion about trim tabs and systems when I start building the left elevator. The service plate for the servo is attached using small half inch long 6/32 or #6 screws. So I was able to use those screws to determine how they would look if I used them to attach the fiberglass tips to the elevators.

SO I committed to that screw size, and proceeded with the dimpling. Cleaveland Tools included both a number 6 and number 8 dimple dies for two different sized screw heads, and you may recall that I have used a #10 dimple die for the screws that attach the lead counterweight. I took a practice peice of metal, drilled a hole with a number 28 drill bit, which by the way is also listed in a wonderful pull out chart that Cleaveland tools inserts into their catalogue. It has decimial conversions, drill bit size charts for specific applications, and  a host of other useful info. Anyway the screw head seemed to fit nicely into the dimple, so I then went ahead and drilled and dimpled the two #28 holes in the counterweight skin E713 and the skin E701 R ( 2 top and 2 bottom holeswhere both parts overlap each other), and then dimpled each hole with the hand squeezer with the #6 dimple die.

One note of concern is that Vans had prepunched all of these tip attach holes with a 1/8 inch CS4-4 countersunk pop rivet in mind. This means that all the holes are spaced from the edge of the skins to provide adequate clearance (2 times the rivet diameter) from the edge of the skins. After drilling adn dimpling using these same prepunched holes as a guide, I am about 1/16 of an inch short of what the proper edge distance should be. However, I think that this rule is only for proper rivet spacing, and does not apply to other fasteners such as screws or bolts, but that may also depend on the material used. IN any event, I am not concerned about this, because there are several other screw attach points for the tip to be attached to the elevator, and if I need to I can drill other holes on the skin to provide a bit more adequate clearance from the edge of the skin. Will cross that bridge when I get to it.

OK, so pics now. Here is the #6 screw, and the nut plate for the trim hardware, and two of the four holes on the edge of the skin and counterweight skin that are now drilled and dimpled for this screw size:

And  a slightly burry pic of the screw inserted into the dimpled hole:

So of course the dimpling had to be done AFTER the frame had been removed from the skin, and then I re-inserted everything again adn clecloed it all together. I also drilled the other holes along the edge to 1/8 or #30. I did not final drill them to # 28 yet just in case I need to adjust the edge distance for he remaining screws.Nore have I dimpled the remaining holes because I can get to them later, and they are not overlapped (or underlapped, as it were) by any other parts like the two holes shown above. So I can drill and dimple the other holes later, even after the elevator is riveted together.

Which leads me to the next two pics. Right elevator is almost completely riveted. Just deciding about pop rivets in the final 2-4 holes closest to the trailing edge. the only thing remaining after that will be the dreaded rolling of the leading edge. I will wait on that until the left elevator is also done. Then I will roll the LEs for both of them to finish them up. It was nice to finally get this one riveted together.

On that note, since I dove into my hardware for the electric trim system, I decided to have some fun and crack open all the parts for the trim system, and I even temporarily wired up the components and attached them to a 9 volt radio battery to see if it works. I also trial fit the trim servo to the attach brackets and trim servo mounting plate. More pics of this to follow as I start on the left elevator. There are bascally three components to this system, the trim tab servo that actuates a pushrod to raise or lower the trim tab, the switch, and an indicator that displays the position of the trim tab relative to the movement of the trim tab servo. I wired it all up and attached the power leads to a 9 volt battery and whala, it worked! Very cool to be messing around with electrically driven parts!