Tanks

 

P7130008.JPG (87067 bytes) 13 July 03 I've started the tanks. Lot's of work to go on these. The Z-brackets have been started by smoothing the edges. #12 bit is creating off-round holes so I have a straight flute reamer on order. Also fit together the tank ribs and skin. Due to the skin thickness, this is a little harder than it looks. I'm also going to use Dan's version of putting together the tanks as this seems like a good way to get the perfect fit. Look here for the gory details http://www.rvproject.com/20020602.html. 
P7160010.JPG (72931 bytes) 16 July 03 1) After drilling one 3/16" hole in the center of one side of each Z-bracket, bolt the bracket to the forward spar with a short AN-3 bolt and tighten it down a bit. Ensure it's square with the spar.
P7160011.JPG (74033 bytes) 2) Back drill from the aft side of the spar. This gives you the three holes through which to mount the AN-3 bolts. Dan's method then had you pull off the brackets and install the nut plates. I just installed the other two bolts in each bracket. This seemed to work out just fine aside from one minor problem. Those with sharp eyes will catch that all these Z-brackets are installed backwards! Dooohhh! Didn't catch this till the next Day.
P7170012.JPG (91128 bytes) 17 July 03 4) Take off all the Z-brackets and turn them around. This took most of the night!

5) Put the cleco'd tank on the spar. Mucho visual progress here. a couple of taps with a hammer on the root end really snug up the tank against the outter leading edge.

6) Cleco the tank to the spar and drill the splice plate holes. I drilled to a #30 then the #19 per plans. So far, so good.
P7170014.JPG (69828 bytes) 7) Per the photo at left, I ended up with a fairly decent joint between the LE and the tank. Cool!
P7170015.JPG (100307 bytes) 8) Next, drill the most inboard z-bracket through the root rib. Here, you can see the clecos. This is a whole lot of visual progress but it's got to come apart very soon...
P7180017.JPG (89845 bytes) 18 July 03 9) Better shot of the outboard end of the tank. The rib/baffle/Z-bracket interface has been drilled. WHile I was at it, I drilled the skin/rivet holes for all ribs and most of the baffle. Be careful as the spar gets in the way so there's some you can't do.

10) Now remove all cleco's from the end ribs and along the skin/ spar, and the skin/rear baffle.
P7180018.JPG (80248 bytes)

11) This is what you ought to have. Rear Bracket sitting on top of the Z-brackets, attached by the end ribs.
P7180020.JPG (82596 bytes)

12) Whip out that 1/8" drill bit and drill teh Z-brackets through the pre-punched holes in the rear baffle. Cleco as you go along. 

13)  Now remove all this, Including Z-brackets. I noticed that the Z-brackets didn't line up exactly on center and the rib/Z-bracket holes are somewhat close to the middle web of the Z-bracket. The rivets do have enough space though. 
P7180022.JPG (91290 bytes)

14) Now, finish drilling the baffle/ rib matched holes and the rest of the skin/ baffle holes you couldn't do on the wing.  Now back to the left wing....
P8310042.JPG (221616 bytes) 31 Aug 03 15) After I had finished riveting the top skins to the wing frame, it's back to the tanks. Since the baffle was still cleco'd to the tank, I figured I'd machine countersink the skin/ baffle holes.

16) While I'm here, I used a 2x4 chunk as backing and opened up all the tank/ spar attach holes to #19. 
P8310043.JPG (216824 bytes) 17) Next was the attempt to drill the fuel filler backing. The bent parts of the flange ares on the forward/ aft side. Actually, after drilling a couple holes, I found that I didn't quite have the fuel cap in the center. Sure....no one else would notice but I would. For $14, I ordered a new one from Van's. 
P8310044.JPG (190427 bytes) 18) I planned on cutting out the 2" x 2.5" angle brackets on the inboard nose of the ribs. The T410 backing plate is shown here drilled to the inboard side of the outboard rib. 
P9030046.JPG (294422 bytes) 3 Sept 03 19) Finished up the two tank attach angles. Band saw really helps here. It's now fitted and drilled to the inboard tank rib. 
P9030047.JPG (291711 bytes) 20) Put the access panel backing plate in place and drill the rib for the platenuts. 

 
P9060048.JPG (201510 bytes) 6 Sept 03

21) Drilled the 7/16" hole for the vent line (upper left) and smoothed out the two large al. washers for the vent and fuel pickup fittings.

22) Fitted the fuel pick-up fitting and fabricated the anti-rotation bracket. Just need to bend the fuel pickup tube.

23) The access plate has also been smoothed and the float mount hole has had the platenut holes countersunk.  
P9140001.JPG (310357 bytes) 14 Sept 03

24) Spent the last couple days finishing up the prep work for the left tank. Ordered and received a quart kit of Proseal. I also ordered a couple of the premixed tubes. We'll see how that works. Bent the fuel pick-up tube and cut the input slots in the end. Fitted the vent tube. Scuffed up all the mating surfaces wtih a rough scotch brite 2" disk. Spent an hour de-vinyling the tank skin as well de-burring same.  

25) Dimpled the skin as well as all the stiffeners and ribs. After whacking the C-frame "I -don't -know-how-many-times", using the pneumatic squeezer on the ribs and stiffeners is almost therapeutic. Also machine counter-sunk the fuel filler flange. So far there's about 22 hours of work in the tank to get to this point. 
P9150002.JPG (228625 bytes) 15 Sept 03

26) First major encounter with the dreaded elephant snot. Nasty, stinky, sticky, stuff!!! But it's not sooo bad. Took an hour to get this figured out and then rivet the plate nuts and backing plate to the inboard rib. Plans say that you don't have to proseal the backing plate but I'm not taking chances.
P9160004.JPG (232053 bytes) 16 Sept 03

27) Not shown but I did seal and rivet the re-enforcment plate to the outboard rib as well as rivet and seal the fuel filler neck. That took the better part of just over an hour.

 
P9160005.JPG (211500 bytes) 28) As part of the filler neck, a good clean up is necessary. I found very quickly that you need to clean all tools after use, especially clecos. Pneumatic and hand squeezers, squeezer dies, cat, and anything that comes in contact with this stuff. Clean rags are better for clean-up than paper towels and lots of MEK. 
P9220008.JPG (272402 bytes) 21 Sept 03

29) Haven't had a lot of time on the RV lately. Had to go fly the Boredom Fighter a bit. I did manage to get the tank drain sealed and riveted. 

 
P9220009.JPG (188568 bytes) 30) Also managed to install the plate nuts and the fuel pick-up fitting with anti-rotation bracket to the tank access panel. Pretty straight forward. Next comes the stiffeners and ribs. 
P9280011.JPG (226338 bytes) 28 Sept 03 31) A couple days earlier I had riveted all the stiffeners in and that ended up working OK.

32) Started riveting in the ribs. This is nasty, stinky, sticky, stuff! It was a little hot in the workshop, and wearing a respirator, latex gloves, and long sleeves, you get a little warm and sweaty. Other than that, it looks like the first two ribs came out alright. It's taking about an hour per rib to get this done. For spreading the pro-seal, I'm using a a small plastic spreader like the squeegie you use for epoxy. This seems to work better than the popsicle stick. Lesson-learned number two: wear two pairs of rubber gloves. When your hands get really nasty sweaty, getting a mucked-up pair off and a new pair on is way easier over a second pair, than your nasty wet skin. Lesson three: I bought a digital food scale at Walmart for $29, and it has a granularity of 1g. To rivet and seal one rib, use 36 grams of the white stuff, and 3.6 (OK, 4) grams of the black stuff. Works just right and not much sealant left over at the end of the session. 
PA050021.JPG (272363 bytes) 5 Oct 03 33) Over the course of several nights, I was able to seal and rivet all the ribs into place. Plan on taking about an hour per rib but the end ribs take a little less time. There's nothing neat about pro seal. It's still nasty, stinky, sticky stuff, but overall, it went fairly well. 

34) Spent an hour today inspecting the ribs for pin holes in the sealant. Found a couple spots which I'll go over when I mix up the next batch of pro seal. I did get the float indicator bent and fitted. The good thing is that it appears to function as advertised, at least with the Ohm meter. The bad thing is that the 3" measurement between the float and the first bend, as called out in the plans, appears to be short about an inch. When the float is in the empty position, all the way to the stop on the transducer, the float is about an inch above the bottom of the tank. The good thing is that when it indicates empty, I still have a little fuel left. 
PA080020.JPG (225791 bytes) 7 Oct 03 35) Spent 2.5 hours this evening installing the rear baffle. This really took a while as there's a whole bunch of rivets! Started with the install of the Z-brackets, and progressed to the span-wise skin-to-baffle rivets. Appears that everything sealed OK. I'll find out in several days. Man, there's lots of clecos to clean... 

At left is the view through the tank access of the first bay, upper skin to baffle joint. I sure hope I had enough pro-seal on this. 
PA110027.JPG (258729 bytes) 8 Oct 03 36)  This evening I pretty much finished up the left tank. Here's the access panel installed as well as the float transducer. I ordered the hex-head stainless #8 x 1/2 screws from McMaster and these seem to have done well. The cork gasket never got installed and I opted for the pro-seal version. I tried a cork/ proseal solution on an oil tank on a Continental A-65 and that didn't quite work very well. This actually seems like a nice, neat install, however, it might take some effort to remove if necessary. 

Soooo, after 40.3 hours, this tank is about done. The only thing left to do is run the pressure test, which I should get done in a couple days. 
PA090023.JPG (301064 bytes) 9 Oct 03 37)  Time to test the tank. I made up a short, flared tube extension to connect with the fuel line fitting. This was then connected to a 3/8" I.D. tube and filled with some water for a manometer. Seemed to work well, but as I've read in a lot of postngs, the fuel tank cap leaked a little according to Mr. Bubbles. I tightened up the cap a little, then used some clear packing tape to seal off the fuel fill. Apparently, this worked well. I couldn't find any leaks in the tank with soapy water.
PA110026.JPG (188541 bytes) 10 Oct 03 38) The black line at the to the left of the tube is the 24" level. I tested this up to about 1 PSI. The red markings were the first try, and the blue, the second. The difference between the upper blue mark and the lower was about 4 inches and was the result of about a 10 degree temperature change overnight. The next day, when the temp went back up, the water level went back up to where it was supposed to. No leak!
PA110031(rev1).jpg (94189 bytes) 11 Oct 03 39) I installed  the tank on the wing and promptly found a doofus error when I had riveted nutplates to the Z-brackets a while ago. Seems I riveted the wrong sige nutplates to the z-brackets and none of the AN3-4 bolts were going to work. Soooo, after drilling all of these out, and replacing with the correct nutplates, everything went together as advertised.  Well, almost. Due to dimpling, pro seal, and whatever, I ended up with some pillowing between the screws on the tank/ Leading Edge splice plate. Yup, it would work. Nope, doesn't look good. 
PA120033.JPG (236384 bytes) 12 Oct 03 40)  This is my fix. I measured and drilled screw holes between the existing holes so instead of 2.5 inched between the screws, now I have 1.25". This is only for the upper surface. The lower is no problem. The tank was removed in about 15 minutes and nutplates installed on the splice plate. Not a big deal but now I have to order more nutplates and screws for the next tank. 
PA120034.JPG (210371 bytes) 41)  Taaa-daaaa. Fixed tank. This ended up looking mucho better than the previous arrangement. Now back to finish up the left wing....