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MIKE
HOWE'S RV7 CONSTRUCTION FUEL TANKS
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March 12, 2002 ASSEMBLING THE FUEL TANKS The fuel tanks are also the inboard leading edge of the wing., so they are constructed in a manner similar to the outboard leading edge. However , the tank is removable so the tank ribs can not be permanently attached to the spar. The tank is attached to the wing in two ways. Flush machine screw fasten the skin to the spar flanges and bolts hold the T-71`2 fuel tank attach brackets (mounted on the rear tank baffle) to the spar web. The tank is also held to the fuselage by the T-405 attach angle bracket. Fuel tank construction and details are on DWG 16A We are going to finish both tanks at the same time FITTING THE ATTACH BRACKETS TO THE SPAR AND REAR TANK BAFFLE Mark a vertical center line on the forward and aft flanges of all the T-712 attach angles. Find the exact lengthwise center of each flange. Drill a 1/8" hole in one flange of each angle. Set one T-712 aside and drill a #12 hole in the center of the other flange on the remaining six. When you are done, six of the attach angles will have a 1/8" holes inn one flange and a #12 in the other. The seventh attach angle will have one 1/8" hole in one of the flanges and the other flange will be blank. Click here for PDF enlargement
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Drilling the tank attach brackets |
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March 15, 2002 Cleco the drilled T-7121 Attach Angles to the aft side of the prepunched spar so you have good access with the drill. Position them so the centerline is centered in the pre-punched holes in the spar. Clamp the angles in place and drill the remaining holes using the spar as a guide.
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Drill holes in attach angles |
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March 15, 2002 Remove the angles and rivet the nut plates to them. The instructions no longer give you instructions on how to install nut plates, as I guess they assume you should know by now, so countersink the backside of the angle for flush rivets, (AN426AD3-4) to hold the plates on.
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Rivet nut plate |
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March 15, 2002 Bolt them in place of the front of the main wing spar. Notice there is just the one hole in the top of the flange you drilled when you made the part. Later on the tank baffle is going to be clecoed there and the other holes back drilled through it as it is pre-punched. Again many of the holes are now pre-punched so it makes alignment very easy and gives you your drill template.. I am pretty much following Van's instructions book as there are many improvements over the old way of doing it where you had to drill the holes. |
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Bolt in place on spar |
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March 18, 2002 If you are following my progress you might wonder why I haven't worked on the wings for a few days, is because I have gotten sidetracked doing the builders group workshop pages, should be through with them in a few days |
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Finally got back to working on the wing after a week with this workshop stuff. If you would like to come to one check it out on the home page link. I finished drilling and putting the nut plates on the spar in preparation for drilling the tank baffle. all but one of the brackets are drilled using the holes in the spar as a template, the last bracket looks like it is not drilled yet as the ribs holes will be used later on to drill, I think! |
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| Finished tank baffle brackets | 
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March 29, 2002 Cleco the baffle to the center holes you drilled when making the brackets and check to see the holes in the baffle line up with the center line you drew on them |
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Cleco the baffle to the brackets |
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March 29, 2002 Here is the baffle clecoed on to the brackets using the one center hole you drilled when fabricating them. Check to see that the centerlines on the angles are visible through the holes in the baffle.
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Cleco baffle to the brackets using the center hole |
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FITTING THE TANK SKINS TO THE RIBS AND REAR BAFFLE Complete and remaining rib preparation details. Bend flanges 90 Degrees and flute ribs. Use a square to check the flanges and a straight edge and/or skin to check the ribs for rivet hole alignment. (This is a very important step as I found out later as when clecoing skin to ribs to drill they need to be aligned and not pulled into place as if puts pressure on structure. Test fit the ribs and skin when clecoing together to drill and further flute and bend flange as required some holes align with forcing them.) Make all T-711 A through D stiffeners as shown on DWG 16A. Round all stiffener corners, Deburr edges, then cleco and final drill them to the T-701 skin. |
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Cut, drill and cleco the stiffeners |
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I am finishing up the stiffeners. Next step. Cleco the tank skin to the baffle (still fastened to the spar) and wing spar. The fit between the spar, baffle, tank skin and leading edge should be perfect. If not, elongate the holes in the baffle inboard or outboard as necessary to allow the baffle holes to align with the T-701 holes when T-701 is clecoed to the spar. |
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| Tank skin clecoed to the spar and baffle. Again I am amazed at how well it fits thanks to the precision of Van's prepunched holes. | 
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March 31, 2002 Remove the T-701 skin and cleco all the tank ribs to the baffle. Drill the rib/baffle/attach bracket holes full size. |
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Cleco and drill rib/baffle/spar |
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March 31, 2002 Use a drill stop to prevent damaging the spar.
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Use a drill stop to prevent damaging the spar. |
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