3/1/2008
Lots of pics today! I started today by making the template I mentioned to locate the 1/4" hole on the ribs. I thought about this for two days on how to do it, and I think this is the best, maybe only, way I could do this. Mike Bullock, an RV-7 builder buddy of mine, had told me about another method, but after looking over what I had already done, with the holes already drilled in all the plastic spacers, I really didn't have much of a choice but to use a template, and hope for the best when I go to drill the frame hinge. Edge distance has been a concern for many tip up builders, but they usually get the typical response from Van's...it's not structural, move on.
So, I made the template, and cleco'd it to the ribs to drill.
Using the spacer for all four ribs will ensure that the pin hole is in the same spot on each one. This worked out pretty well!
The instructions say to run a .251 reamer backwards thru the plastic spacers to ensure a nice slip fit of the pins.
Here's the stack of spacers in place with some temporary bolts.
That's where those are left for now...on to the canopy jettison mechanism. This is something that many builders are choosing not to put in because the probability of getting the canopy off during flight is fairly slim, and even if it did exit the airplane, I would have to be wearing a 'chute all the time to make it worth jumping out... ;o) So, why am I installing it? For ground maintenance. I doubt I would really ever need to take the canopy off, but if I ever did need to, this will make it very easy. I am not going to run the release handle thru the panel. Instead, it will run straight down vertically off the bellcrank. I also decided to put it in for another pound or so of weight up front where I need it. I'm trying NOT to use dead weight if I don't have to, so this is a functional part that adds a small amount.
To start out building the mechanism, you have to drill holes and make slots in steel tubing. Yippee. I HATE working with steel! My holes are slightly off, but they should work. Many builders who do put this part in, use a cutoff wheel in a drill press. I thought about this a bit, and decided against it because the slots have to be widened somewhat further than the cut off wheel is wide. Seemed a little more difficult that way. So, my trusty Dremel tool goes to work again!
With those done (I may need to remake the short one...my slots are not in line with each other, end to end. I'll have to see if it binds the bellcrank later on), I made the hinge pins by cutting off the threads of a couple of shoulder bolts.
Next, I drilled the bellcrank block to the "hat section". I marked the first hole and drilled it without the block, then put that bolt in and clamped it to drill the other hole.
Then I ran in to a problem. Since I fully riveted the sub panel together a while back, I had VERY restricted access to get the platenuts in for the block bolts. Now, back when I built the sub panel, I was not planning on using the jettison feature, so I didn't think this would be a problem. If you're reading ahead, and see this paragraph before you've built your sub panel...DON'T RIVET THE HAT SECTION or RIB 644 until your past this point! Another example is coming up...Anyway, I figured out how to get the stupid platenuts in the hat section. Here the holes are drilled.
Since I had no way to get a squeezer or bar behind the hat section, I had to use blind rivets here. No big deal, and they'll never been seen...just holding platenuts anyway.
So, another example of why you want to wait on riveting some of this stuff together...I needed to make the clearance holes in the hat section for a bolt, and another hole in the center panel rib for the pushrod to go thru. First, I mounted the block to figure our where the holes needed to go.
Then I used drill bits, snips, and the cutoff wheel in the Dremel to make the holes.
I also trimmed the top of the "hat" for clearance with the pushrods. Pretty much a pain in the ass day, but I still was happy to be in the garage.
4.75 hours