Home > Tanks > Started Left Tank Inboard Rib Modifications

Started Left Tank Inboard Rib Modifications

October 11th, 2012

Match Drilled the T-405-L to the Rib

With the T-405-L fabricated, it was time to drill it to the rib. I laid out the rivets as close to the drawing provided since there really is not a list of dimensions for each rivet anywhere, so it really is an “eyeball it” or best guess anyway. I simply worked it to insure good pitch and edge distance and drilled away. Once that was done, I inserted the bracket into the nose of the inboard rib of the left tank to prep it for match drilling to the rib.

Inside T-410-L Drilled to Rib

On the other side of the rib is the T-410 that also gets match drilled to the rib with the T-405. It creates a sandwich and also helps reinforce the nose of the rib. I also think it helps later in the sealing the nose of the rib with sealant by closing the gaps where all the tabs are. Here you can see the rivet holes drilled to the rib and the T-410-L.

Flywheel Cutting the Access Port Hole

Once the nose was done, I moved on to cutting out the access port hole. It is a good size hole and I had to use my Fly Cutter. I have had this tool for some time [aka long before thinking about building a plane] since it works will to cut centering rings for large rockets. It was nice to have on hand to complete this task. It is actually a pretty quality tool. Some have used ones from Harbor Freight, that look as cheap as they are. Mine worked well. You can see here the center of the hole after I was able to finish the cut. Took longer to set up then it took to cut the hole in the rib.

T-407-L Riveted to T-703

After deburring the new large hole in the rib, I located the position of the T-407-L reinforcement ring and match drilled it to the rib. This went pretty quick since I had deburred the T-407 some time earlier. I then countersunk the ring and dimpled the rib and used my pneumatic squeezer to attach the platenuts to the rib and ring. I really felt like I was moving along tonight.

Reinforcement Ring Installed with Platenuts

Here is the backside of the rib with the ring and platenuts. Looks pretty good to me. Since the plate is on the inside of the rib, there is no real need to seal it to the rib. Any leak path would simply return to the inside of the tank. The screws and rivets will be sealed by sealant when the access cover is attached.

Hard Parts Done

By the time the night was spent, I was able to slip the cover over the access hole and hand thread some screws to hold the cover in place. You can see here I have some markings on the cover. Since I am not using the float senders for fuel level, the stock covers can be tossed. However, the covers supplied with the capacitive senders are not pre-drilled for the fuel pickup. Some builders install flop tube pickups, so Van’s ships the covers blank. I simply used the stock cover and marked the location of the pickup tube and anti-rotation bracket holes for reference. I will eventually use the stock cover to match drill for the anti-rotation bracket. Then I will use a step drill to open the hole for the fuel pickup.

The time has arrived to decide if I intend to install a flop tube in one or both of my tanks. Short answer, I am not in either. I have read where they can stiffen up. I’d rather avoid maintenance issues inside my tanks. Additionally, in order to truly take full advantage of inverted fuel, you have to install fuel injection (which I am planning on) and an inverted oil system (which I do not intend to do) in order to enjoy sustained inverted flight. I just do not think that I will do any extended negative G maneuvers. Others report that they get 20+ seconds of good fuel flow without a flop. Again, do not think it will be something I want to add to my flying. So, I feel that I will get all the excitement out of my plane with standard fuel pickups and be just fine. I will still have good ability to do “gentlemen” aerobatics without the hassles of possible maintenance issues. That, and it conforms to the KISS [Keep It Simple Stupid] principles.

All in all, it was a great work session for an “after work” day in the shop. Next up is fabricating the T-405-R and repeating the above completed work on the right tank rib.

Categories: Tanks
Comments are closed.