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RV-8 Tank Baffle

Little Wing

Active Member
Any RV8 builders dimple their tank baffles? I read threads from other model builders that have with success. With the RV8 the first ten top inboard rivet holes are awful close to the doubler bar! Okay to countersink these and dimple the rest?
Any comments appreciated!
 
Tanks

Any RV8 builders dimple their tank baffles? I read threads from other model builders that have with success. With the RV8 the first ten top inboard rivet holes are awful close to the doubler bar! Okay to countersink these and dimple the rest?
Any comments appreciated!

7 and 8 tanks and wings are similar. The rivetz are close but they don't touch the spar cap. Assemble it with clekos and double check but there should be plenty of space for the shop heads.. What does come close is the proseal dollops and the proseal fillet along the baffle edge. One trick when you get there is after the rivets are set and you put dollops and a fillet on the baffle, set it aside for a day then put wax paper on the spar and install the tank with a few screws. When you pull it off the wax paper will come right off and the proseal will be shaped to the spar cap.
 
I considered dimpling but ultimately decided to countersink per the plans. The main reason for this was that the baffle flange looks like it'd be a pain to dimple - pretty tight quarters there.
 
Tank Baffle

If I had it to do over again I would dimple. I believe dimples would help keep the baffle aligned during riveting. With countersunk holes there is enough clearance in the holes to allow the baffle to walk a little during the rivet process.
 
Modified Countersink Method

I debated this for some time, searched VAF, asked every builder in my chapter and examined many finished aircraft. In the end I decided there was a greater chance of getting a gap in the ProSeal if I dimpled, so I decided to countersink the holes. To prevent the baffle from walking during riveting, I deferred countersinking every third hole until after assembly.

I loaded ProSeal into a Ziploc bag, snipped off the end and piped a bead of ProSeal around the edges like a cake decorator. It took about 100 grams of ProSeal to do the whole baffle. Once I had a nice bead along all the rivet holes, I added some extra sealant around the corners (because this is a common area for leaks) and then dropped the baffle straight down into place. I started clecoing by doing all the ribs first, then I clecoed every third hole, which had not been countersunk. Once all these were in place, I went back and clecoed the holes that were countersunk. I let this set up for a few hours before I began riveting.

I started riveting according to the plans with the top and bottom rib holes, and then riveted the T-712 Z-brackets with pulled rivets. Next I put solid rivets in the sides and then riveted the skin to baffle holes that had been countersunk. Once all the countersunk holes were riveted, I removed the remaining clecoes, countersunk the holes I?d skipped during the skin prep, added a little ProSeal to the holes, and riveted them.

This method kept the parts in alignment well and I didn't have any leaks.
 
Baffle

I debated this for some time, searched VAF, asked every builder in my chapter and examined many finished aircraft. In the end I decided there was a greater chance of getting a gap in the ProSeal if I dimpled, so I decided to countersink the holes. To prevent the baffle from walking during riveting, I deferred countersinking every third hole until after assembly.

I loaded ProSeal into a Ziploc bag, snipped off the end and piped a bead of ProSeal around the edges like a cake decorator. It took about 100 grams of ProSeal to do the whole baffle. Once I had a nice bead along all the rivet holes, I added some extra sealant around the corners (because this is a common area for leaks) and then dropped the baffle straight down into place. I started clecoing by doing all the ribs first, then I clecoed every third hole, which had not been countersunk. Once all these were in place, I went back and clecoed the holes that were countersunk. I let this set up for a few hours before I began riveting.

I started riveting according to the plans with the top and bottom rib holes, and then riveted the T-712 Z-brackets with pulled rivets. Next I put solid rivets in the sides and then riveted the skin to baffle holes that had been countersunk. Once all the countersunk holes were riveted, I removed the remaining clecoes, countersunk the holes I?d skipped during the skin prep, added a little ProSeal to the holes, and riveted them.

This method kept the parts in alignment well and I didn't have any leaks.

That's a great idea!
I used a scrap rivet every few holes to hold alignment. I also fay sealed both surfaces then applied the bead per Vans direction. When I installed the inboard and outboard ribs, I built up the aft corners so it wouldn't take a huge glob to fill those corners.
 
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