Now that the aileron assembly is pretty much put together, I now need to focus on the aileron spars which still have a bit of work outstanding. What I need to do now is to dimple the spar caps, and also to cut out the lightening holes that run the length of the spar.
I started with the dimpling because it’s easy to do.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_101044-940x940.jpg)
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_101056-940x940.jpg)
Lightening hole layout
The first task of cutting out the lightening holes was to measure the location of the holes along the spar. I started by measuring in 5 inches from the inboard end. The holes are 2 inches in diameter and are on 2-3/4 inch spacing.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_104457-940x940.jpg)
For cutting the holes, I started with a piloted center hole in each location. Then I used the Noah Industries ARC-360 hole cutting tool. It’s basically an angle grinder with a cutting bit and a hole cutting frame assembly, which is adjustable for holes from 1.5 inches up to 10 inches. It’s available from Aircraft Spruce and costs about $150 USD. This tool worked really well to make accurate holes. I prefer using this over a hole saw. I feel it gives me much more control. If you plan to use one, just make sure your pilot hole is quite a snug fit, as that centers the pivot of the entire tool.
Once the holes are cut, they are a bit jagged, but they clean up quite easily with a file and some scotchbrite.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_130623-940x940.jpg)
Here’s another view of the ARC-360 tool and the radius adjustment plate.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_130648-940x940.jpg)
When cutting the holes, I just clamp the spar material to the workbench and start slowly working an area with the cutting bit until I break through. Then It’s just a matter of working the cutting bit around in a circle.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_130731-940x940.jpg)
And before you know it, all the holes are cut and then I moved on to the other spar.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220312_134802-940x940.jpg)
A little riveting
With the spar lightening holes done, I was able to get the spars primed. While waiting for the primer to dry, now was a good time to get the stiffeners riveted on to the aileron trailing edge skins.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220309_193254-940x940.jpg)
Once the stiffeners were riveted, I was able to put the aileron together as a complete assembly. There isn’t much more I can do here on the ailerons until they go through their pre-cover inspection. So for now, the ailerons are as complete as I can make them. Time to set them aside and move on to other parts.
Please comment. I love to hear from my readers. Thanks again for coming along for this ride, you make my work worthwhile.
![](https://f1rocket-hangar.com/wp-content/uploads/2023/01/20220309_204935-940x940.jpg)
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