Vertical Stabilizer 6-3 to 6-4-3
In this section I started to work on the skeleton for the vertical stabilizer. The first steps involve deburring all the rib edges, and the plans specifically called out rounding the edges of the leading nose ribs to avoid dents forming in the skin due to faceting.
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| Vertical stabilizer skeleton pieces |
My initial attempt at rounding the leading edges of the ribs looked like the middle photo below. For comparison, the rib started off looking like the photo on the left. However, when I did an initial fit of the the vertical stabilizer skin to the ribs (and a tight fit it was), I ended up with a very small dent being visible on one side where the middle nose rib was attached. I obviously hadn't rounded enough!
So I took the skin off and proceeded to remove more material from the leading edge of the nose ribs while rounding the edges even more. The end result was the ribs looking like the photo on the right. Reattaching the skin, it was still tight but I didn't notice any more dents appearing at the leading edge.
Rib with no deburring Initial rounding attempt Final rounding
Maybe I didn't need to take off so much material, but I really wanted to make sure that I didn't cause any more dents in the skin. I was, however, careful to leave enough hole edge distance on the rib leading flanges, and to not leave any sharp corners that might cause cracks in the future.
Clecoing the ribs, front and rear spars together gave me my first impression of how the vertical stabilizer would end up looking. Nice to see a major component coming together!
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| Starting to look like a vertical stabilizer |
One thing I noticed here was that the ribs did not lay perfectly flat when resting on the workbench, and when clecoed together, I wasn't happy with how curved the whole skeleton looked. The plans didn't specifically call out straightening the ribs, but I did as several other builders have done and pulled out the fluting pliers to remove the bend in the ribs. This was my first time using fluting pliers, so I watched the Cleaveland fluting demo video and went slowly, gradually added flutes until the ribs were straight. I was very happy with the results! Nice straight ribs!
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| Ribs fluted and leading edges rounded and deburred |
For the skin, I used a soldering iron to remove strips of protective blue plastic on the outer surface around the holes, match drilled the holes to the skeleton and then marked off holes with tape that are not to be dimpled.
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| Vertical stabilizer skin ready to dimple |
I also marked off holes on the bottom rib that were not to be dimpled and made sure those holes corresponded to the ones in the skin.
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| Several holes marked with tape not to be dimpled, as screws will be used in those holes at a later time |
Now it was time to start dimpling. First up was the vertical stabilizer skin (#40 dimple). This was awkward to dimple on my own with the DRDT-2 due to the shape and size of the skin, but I managed to dimple most of the holes myself, using the DRDT-2 for the interior holes and the pneumatic squeezer for the edge holes.
There were, however, several holes along the middle (front spar) row of rivets that I couldn't dimple because it involved simultaneously pulling the skin sides apart while maneuvering the skin into place on the DRDT-2 and pulling the handle. I just couldn't do it with just two hands. My wife helped me here by holding the sides apart while I dimpled. Her first (of many, I guess) contributions to the RV-10 build!
The only other holes I couldn't dimple with either the DRDT-2 or the squeezer were the holes where the middle leading nose rib is attached. This is because there is very little space in here and it is impossible to pull the skin sides apart enough to comfortably seat the holes in the DRDT-2.
So here I used the 3/32" close quarters dimple die set from Cleaveland Tool. My initial attempt at forming the dimples with the copper mandrels resulted in under-formed dimples, and several broken mandrels. I would have tried the steel mandrels, but the ones supplied in the set did not fit the dimple dies.
Instead, I ended up using some LP-4 pull rivets (that I had left over from practice kits) as mandrels. These worked really well due to the mandrel being steel, and I was able to form 3 to 4 nice, crisp dimples from a single LP-4 rivet before it became too stretched. I also highly recommend this rivet puller I recently got. It replaced one I initially purchased from Aircraft Spruce that just didn't work.
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| Tight fit dimpling with an LP-4 pull rivet |
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| Vertical stabilizer skin all dimpled |
The next steps involved countersinking and dimpling the holes of the rear spar where the skin attaches. Before doing that, I made myself a countersink depth gauge using aluminum from the empennage trim kit. I could use this to check if the countersinks were deep enough to accept the skin dimples. Fabricating the gauge, I dimpled a hole for a 3/32" and 1/8" rivet, and #6, #8 and #10 screws. This way I can reuse the gauge in future for different countersink sizes.
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| Countersink depth gauge |
With the 3/32" countersink cage dialed in (7 notches (7/1000") below where the rivet sits flush as recommended in Van's Section 5), countersinking went smoothly but did take some time due to the number of holes.
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| Countersinking the rear spar flanges |
With the rear spar all done, I moved on to page 6-4 and dimpled and countersunk the front spar and front spar doubler.
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| Front spar doubler countersunk to accept dimples in front spar |
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| Finishing the rudder hinge brackets |
The last preparatory step before priming and riveting the vertical stabilizer together involved preparing the rudder stops. The instructions state to heavily debur the rudder stops, so I went at them with the bench grinder deburring wheels. Below are the before and after shots.
Rudder stops before... ...and after deburring heavily
Finally I did an initial cleanup of all parts (including the inside face of the vertical stabilizer skin) using acetone to remove any markings and fingerprint residue.
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| Parts ready for priming |
The next step will be priming, however before doing that I will start working on the rudder so that I can combine priming of the vertical stabilizer and rudder parts in one session. For now I will pause on the vertical stabilizer, and continue once I have rudder parts ready to be primed. Stay tuned!
Build Hints
- When rounding the leading edge of the nose ribs of the vertical stabilizer, remove more aluminum than you think. The plans don't specify how much to remove, but if you don't remove enough you risk leaving small dents in the leading edge of the vertical stabilizer when the ribs are installed.
- Even though the plans don't specify to do so, flute the ribs as necessary to lay flat.
- The plans call out final drilling holes in several places. Don't do this if you received your kit recently as all holes are already final drilled. If you do so, you risk enlarging holes unnecessarily.
- Having a helper makes dimpling the vertical stabilizer skin much easier.
- Use LP-4 (or equivalent) pull rivets when tight-fit dimpling for crisper, better formed dimples
- Fabricate a countersink/dimple depth gauge for use throughout the build.
- Use a drill press when drilling larger holes as it helps to ensure hole roundness.
Time Taken: 12.8 hours
Dates: July 2 - July 7 2022
Vertical Stabilizer Total Time: 20.2 hours
RV-10 Build Total Time: 20.2 hours