Archive for October, 2010

Preparing to Rivet Tank Stiffeners – 2.5 hrs

October 31, 2010 Leave a comment

Sunday Oct 31, 2010

Next up in the process of preparing to rivet the tank stiffeners to the skins is to scuff up the surfaces that will be sealed. But first I deburred the holes using a deburr bit in my Ryobi electric screwdriver. It turns really slowly so its not aggressive. Then I started scuffing. This is just boring, laborious stuff. Here you can see the scuffed region for the ribs, stiffeners, and baffle on the lower surface of the left tank skin. Half way though I found that using the orbital hand sander with a scotch-brite pad attached got the job done much faster. But you have to be careful to use just the edge of the sander to confine the zone to the regions under the ribs and such.

Then I dimpled the holes in the skin for ribs, stiffeners, and the fuel cap flange. I almost dimpled the holes for the fuel drain but just in  time I noticed that the countersinks are on the outside surface of the drain flange. Don’t dimple the skins for the drain!

Then I masked off the regions around the stiffeners with electrical tape so I can keep sealant off the surfaces for the ribs when installing the stiffeners.

Categories: Fuel Tanks, Wings

Finishing the Vent Lines – 2 hrs

October 30, 2010 Leave a comment

Saturday Oct 30, 2010

I made a second diagonal anti-hangup bracket this morning in a mirror image of the one I made last night for the left tank and I installed the new one in the right tank. Here you can see it installed with the flop tube.

After that I left to go visit one of my daughters in college in Santa Clarita. One the way home in the afternoon I stopped to see Eric, another builder in Irvine who I just recently met on the SoCal Yahoo Groups who is building an RV-10. He volunteered to let me use his Parker Rolo-Flair tool to flair the ends of my vent line tubes. I know I’ll have to buy one of those sooner or later but right now the cash is going to go toward other things like a heated pitot tube. Eric was great to let me use the tool and we talked for about a half hour about our building history. It took about two minutes to actually flair the two tubes. Thanks Eric!

Once again back home I measured the length of the offset and the run I needed in the joggle to shift the line of the tube from the hole in the inboard rib to the line of the pre-drilled holes in the other ribs. Then I made two 25 degree bends with my tube bender. With the inboard and outboard ribs removed, I inserted the tube all the way to the joggle. Then I installed the inboard rib and mated the tube to the fitting. Then I marked the outboard end of the tube where I needed to cut it to fit just shy of touching the outboard rib. I cut the tube using a small cut-offf wheel on my rotary tool. Then I had to take the inboard rib off again, remove the tube and deburr the end. And put it all back together. In this picture you can see the vent tube installed along with a reflection in the upper surface of the skin. The real tube is the lower one.

Then I took the entire left tank apart to start preparations for final assembly and sealing. I laid the skin on the work bench and match drill the stiffeners to the lower surface as seen here.

Categories: Fuel Tanks, Wings

Diagonal Anti-Hangup Brackets – 1 hr

October 29, 2010 Leave a comment

Friday 29 Oct, 2010

Another short night in the shop as I get closer to being ready to start the assembly and sealing of the tanks. Tonight I made the diagonal anti-hangup brackets for the flop tube. These brackets keep the flop tube from getting hung up on the aft stiffener in the first bay. It is made from scratch from 0.020 thick aluminum sheet stock supplied in the kit. I cut the strip 0.75 wide and tried several ways to bend it to get a decent fit. The trial piece was kind of ugly after re-bending it several time so I made a right a new one to match the final version that fit. I drilled one hole through the stiffener and one through the 2nd rib and dimpled for an AN427AD3 rivet to come later.

Categories: Fuel Tanks, Wings

Fitted Outboard T-410 Plates – 0.75 hr

October 28, 2010 Leave a comment

Thursday Oct 28, 2010

Tonight I match drilled the T-410 reinforcing plates that are installed on the outboard ribs of the fuel tanks. I marked the plates at six points for rivets, drilled the holes on the drill press, and then clamped the plates to the ribs and drilled through. After deburring the holes I was done. Oh yes, I marked each one so I won’t get them mixed up later.

Categories: Fuel Tanks, Wings

Installing Fuel Senders – 8 hrs

October 27, 2010 Leave a comment

Wednesday Oct 27, 2010

I took the day off from work today to get a few loose ends taken care of and take a flying lesson. The weather has been unfavorable for flying lately and I am close to taking my check ride so I wanted to get some prep in while the skies are clear. Unfortunately the winds were so high I had to scrub the lesson so I got a good bit of time in the shop.

The objective for today was to install the two fuel sender in the 2nd bay of each fuel tank. This is the recommended location if you install flop tubes which I did. But the instructions are vague at best so I relied on tips from Rudy Greylings web site.  Thanks Rudy.

I started with the T-708 access plates which I did not use because I installed flop tubes and used T-411 access plates instead. I cut out the central region where the sender normally mounts to make a reinforcement ring for the baffle. Here is a photo of one original T-708 and the improvised reinforcement ring I made from the other T-708.

Then I located the ring on the baffle near the inboard edge of the 2nd bay just far enough away from the Z-bracket for clearance. I match drilled the holes for the screws and the rivets and traced the center hole on the baffle.

I don’t have tools to cut large diameter holes in metal very easily so I brute forced it. First I drill an array of hole around the inside edge of the cut line.

Then I took a small grinding wheel in my rotary tool and cut along the dotted line to remove most of the material.

Then I used a sanding drum on the rotary tool to remove the excess material up to the circle. Not super precise but plenty good for a clearance hole.

Then I dimpled the rivet holes in the baffle and machine countersunk the holes in the reinforcement ring and installed the fuel sender with a couple clecos. I’m going to rivet the ring to the baffle with nutplates and tanks sealant later.

Next I bent the float wire according to the instructions and installed it on the sender.

Here is how the sender looks inside the tank with the outer two ribs removed so you can see in. Not bad. I also check the resistance of the sender with an ohmmeter at the full and empty positions and the readings were right where they should be (247 ohms full and 31 ohms empty).

I also located and drilled a hole in the inboard rib for the vent line fitting. Here it is with the fitting installed.

Here is the outside of the rib for reference.

Last but not least I made a couple of extension tables for my DRDT-2 dimpler. I should have made these for the empennage but I put it off until now. I’ll need them for the wing skins and leading edges.

Categories: Fuel Tanks, Wings

Installing Left Flap Door – 1.5 hrs

October 25, 2010 Leave a comment

Monday 25 Oct, 2010

Tonight I installed the Flap Door in the left fuel tank on the 2nd rib from inboard. I also installed the closeout plate over the hole in the center of the left circular dimple.

In case you are interested, here is the inboard rib anti-hangup bracket and flop tube as it looks inside the tank with the baffle removed.

And here is the 2nd rib with the flap door and closeout panel installed.

A “quart” of black death (aka fuel tank sealant) arrived today via UPS. The dreaded sealing phase starts soon. I’m not sure I’m ready for that.

Categories: Fuel Tanks, Wings

Making Anti-Hangup Brackets, Flap Doors – 7 hrs

October 24, 2010 Leave a comment

Sunday Oct 24, 2010

Today I made the flop tube anti-hangup brackets for the access cover. I did not like the Vans design because it is permanently mounted inside the tank where it blocks the access hole. So I based my design on one made by Jason Beaver that mostly mounted to the inside of the access cover so the view is wide open when you take the cover off. The trick is how it is split into two sections to allow the majority of the bracket to come out through the access port hole.

I spent a few hours planning it and cutting out pieces until I was happy with it. Once I had one made, I copied it for the other tank. Here is the result. It is actually four pieces of 0.025 thick aluminum strip. 0.8 inches wide. The long strip is mounted to the access cover with two pieces bent into Z shapes. The fourth piece is a C-shape and it is there to prevent the flop tube from getting under the longer piece.

Once those were made I was able to rivet the reinforcement rings and nut plates to the rib along with the short C-shaped pieces. Here are both inboard tank ribs with the nut plates installed. The Z-brackets won’t be riveted until my fuel tank sealant arrives because these must be sealed.

Next I made two square plates using 0.025 aluminum to close out the large hole in the center of the second rib in each tank. This is to retard the flow of fuel out of the inboard bay during maneuvers so the flop tube don’t suck air. Here is one installed with four rivets in the corners. There are no instructions for these. You just have to wing it (pun intended).

Next up was to make the Flap Door for the second rib. This acts like a one-way valve (albeit a leaky one) and also retards the flow of fuel from the first bay to the second bay during wing down maneuvers. There is a general description of this on drawing 16A but no specific dimensions so I had to figure this one out myself also. The hinge material is from the stock for the flaps. It is longer than necessary so I cut 2 1/2 inches off each piece. Then I measured the dimensions I needed for the lap from the rib itself and cut the hinge so I had a little tab bent upward to act as a stop for the flap. I also made a shim of 0.025 thick aluminum to put under the hinge where it mounts to the rib so the flap would sit flat against the rib.

Here it is installed on the right #2 rib. The hinge pin is bent 90 degrees on one end then I used safety wire to tie it to the rib through two small holes I drilled.

That’s it for today. Tomorrow I will install the other flap door for the left tank.

Categories: Fuel Tanks, Wings