September 17, 2006
Today I decided to do some more tank work and flute the tank ribs. These ribs have holes that are a lot closer together and require strict attention to detail. Here you can see me using the straightedge to check the holes for straightness.
Here is a picture of all the ribs for both tanks all fluted and ready to cleco to the skins.
September 20, 2007
Today I marked and drilled the Z-brackets. First thing you have to do is determine the center (lengthwise) of the Z-bracket and then mark the center between the ends so that you have a starting point when attaching it to the main spar. In this picture you can see the Z-brackets marked and ready for the initial drilling
How Do you drill Z-brackets? Very carefully and you probably want to surf around and see how others are doing their Z-brackets because they are so critical to the skin alignment. I personally followed Dan Chekoway and his method because of his excellent documentation and the way that his tank alignment turned out. Fist I clamped a wood block in the drill press so I had something to steady the Z-bracket while drilling the bracket. Next I put the bracket on the block and checked to make sure the drill press would center on the marks. After some adjusting, I could drill all 7 brackets the same each time.
Here is a picture showing my drilling jig.
Once all 7 brackets were drilled with the center hole, I had to debur the z-brackets and mount them to the spar for final drilling. I used some scrap AN365-3 bolts and washers with nylon lock nuts to holt the Z-brackets in place. You have to make very certain that the brackets are straight. Best way for me was to look from under the spar and make sure the line was centered in the hole. I then double-checked with my straight-edge.
The above picture is actually the reverse of how they are mounted (nutplates are used) but it works great for drilling purposes. I decided to call it a night at this point so that I could get some quality time in with the birds and Jenni.
September 23, 2007
I finally got some time out in the shop and was able to final drill the Z-brackets to the main spar. Here is the fruit of my labor on that. If you go slow and take your time, you will be fine on these.
October 1, 2007
Next I clecoed together the tank and let me tell you, that was a major pain in the butt. To say that I wrestled it together would be an understatement. I was actually sweating inside our air conditioned home wrestling this thing together. I was not happy at all with how hard it was to bring this together. Next, I had to take the tank out to the wing and put it on with the leading edge just so I could see what it looked like.
Ok, not really. What you do next is put the tank on and use the tank skin hole to drill the attach strip and attach strip. Didn't do that yet because I was not too happy with the fit of the tank. The gap seemed to be a bit too wide for my liking. Here are a few pictures to highlight was I was talking about.
Frustrated, I decided to hit the group up for some suggestions and got pointed in the right direction with some good ideas for drilling the tanks and making a good fit.
In November we decided that we were going to farm out the building of the tanks and have Evan Johnson of Evans Aviation Products do our tanks. He will Install Flop Tubes, capacitance fuel probes, fuel injection return lines and do it all for about the same price that Van's was charging for Plain Jane tanks with float senders and no FI return line.
So I called Evan and started talking to him about the tanks. He was very helpful and answered all of my questions without hesitation and gave me a good sense that he could do the job without any problems. At the time of this update (February 2007) Evan is about 4 months out because he is pretty backed up from a hand injury.
Do good work Evan...I am giving you a free plug here!!!
I got the tanks back from Evan Johnson of Evans Aviation Products. Evan built my tanks and the pictures do not do justice to just how fantastic the tanks are. In this first picture you can see just how busy that first bay is. You can see the fuel door and flop tube in the foreground. The fuel injection return line is just below the capacitive fuel probe wire (in the picture) and just below that is the vent line.
This next picture you can see the other bays better.
In this picture you can just barely make out the Service Bulletin issued by Vans directing that safety wire be used to secure attach points.
And finally the inboard side of the tanks where the fittings are located. The fuel supply line is obscured by the forward attach point, but trust me it is up there.
Installing the tanks proved to be an entirely different animal. Before you install your pre-built tanks, be sure to rinse them out thoroughly. After you do that and they are all dry, you need to locate the tanks on the spars and drill the z-brackets for mounting. Since my wings are in a cradle, that required the use of tow straps and 2x4's to hold the tanks up in place. It actually isn't too difficult to accomplish, just be sure that your straps are over a rib and that your 2x4's are over a couple of main ribs along the rear spar.
First I had to ratchet the tank into place, get the fit right, and then drill the holes in the Z-brackets and the tank attach strip. Once the holes were drilled, I removed the tanks, deburred the holes, and drilled for the nutplates on the Z- brackets. Once I installed the nutplates, I had to dimple the holes for the tank attach points. This was fairly easy because there was no drilling in place. I drilled off the spar since the spar already had nutplates installed. The tanks were ready to go back onto the spar, right? Oh wait, I have to install the nutplates on the tank attach strip first.
Here are some pictures of the completed attach strips with the nutplates installed.
I repeated the same steps as before to get the tank back in place on the spar. Then I started installing screws and AN3 bolts in the Z-brackets - OMG are my arms sore after that little adventure. I got some waving between screw holes where the tank attaches to the spar, but after looking at other completed RV's, at Copperstate 2008, that seems to be something that can happen.