As get closer to being able to drill the fuel tank skin, I still need to do a bit more prep work by cutting the access hole into the T-403 end rib.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231128_161746-940x940.jpg)
With the end rib access hole cut, I now have access to the entire fuel tank.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231128_162857-940x940.jpg)
Next up was to centerpunch and drill the skin.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231128_164626-940x940.jpg)
I drilled the skin with a small pilot hole (5/64-inch), so that when I matched the holes to the ribs, that would be drilled at the final #40 size.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231129_142855-940x940.jpg)
With the drilling complete, I quickly deburred the holes. I know it will all be drilled again, I just don’t like working with the sharp edges and try to eliminate possible scratches to the metal skin wherever possible.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231129_153216-940x940.jpg)
Then I reassembled the the ribs and tank baffle back into the skin, using the backing board with some wooden spacers to hold the straps from crushing the skin.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231129_160856-940x940.jpg)
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231129_160910-940x940.jpg)
When tightening the straps, don’t forget to check the ends to make sure you take up all the slack in the skin to make it tight against the ribs.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_101555-940x940.jpg)
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_101612-940x940.jpg)
When I was satisfied that I had the skin as tight as I could against the ribs, I worked the ribs to get them aligned along the drilled holes, looking for that centerline that was drawn on the rib flange. Then I started drilling. I started drilling as close to the leading edge as the jig would allow. As you can see, I’ll have to go back, after I drill a few more holes, and pull the tank out of the fixture a bit to be able to access the most forward holes.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_111813-940x940.jpg)
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_121109-940x940.jpg)
In the picture below, you’ll notice that I’ve started to use some wing-nut clecos. I found that these worked really well along the lower side of the fuel tank where the ribs have a slight undercamber to them. This helped me to be able to hold the skin tightly against the rib. This worked out better than using a standard cleco. Once the line of rivets was drilled, I then started on the next high line of rivets and just moved these wing-nut clecos up one by one, replacing them with standard clecos as I went.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_154858-940x940.jpg)
Here’s a picture of the upper tank surface as I’m drilling.
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231201_154907-940x940.jpg)
I’m almost there…OMG there are a lot of holes here!
![](https://f1rocket-hangar.com/wp-content/uploads/2024/03/20231205_170618-940x940.jpg)
I eventually did finish drilling this tank skin. When this task was done, I too was done for the day. Like I said, that is a lot of drilling for one build session. Ugh!
That’s all for today folks! Please comment. I love to hear from my readers. Thanks again for coming along for this ride, you make my work worthwhile.
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