Upper cowl hinge refinement

Previously, I mentioned wanting to work on the hinges for the upper cowl before moving on to drilling the side hinges. To recap, the reason for tapering the hinge eyes is to improve the fit where the cowling curves are the tightest – and more specifically, to make it easier/possible to put the cowl in place from directly above. None of this would be necessary if the cowl could be slid in place from a forward position, but that’s not going to be possible once the side hinges are in place.

So tonight I went to work on those hinge eyes with a file. Overall, it wasn’t as tedious as I was expecting, though it still wasn’t exactly a lot of fun. One thing I realized as I did this is that the end goal here isn’t for the cowl to drop right in place from above – that’s just not going to be possible with the way the sides wrap around and down. Instead, I think it’s fine if I can drop the middle (ie not so curved) portion of the cowl in place, and then work the sides into proper mating just by manipulating each side a bit. This still gets me the real goal, which is to be able to get the cowl in place without having to slide it forward/back.

In the end it took just a couple tries to taper the pertinent eyes, and then I was able to get the cowl to pop in place like I wanted. One more little thing out of the way…

With the upper cowl dropped into place yet again, I took a bit of time to look over the alignment on the sides, and I think I’m going to have another item to cover before I can drill those hinge halves. You see, near the front corners of the cowl, where the upper and lower don’t line up perfectly, that misalignment may make it tough or impossible to get the upper cowl to nest properly with the hinge halves. I didn’t spend a ton of time really evaluating the fit, but it may be that I have to address the alignment of those corners – via adding layup material and/or carving out the inside material some – before I can do the drilling.

Working on the cowl is really an interesting love/hate thing. On the plus side, seeing the airplane with the cowl on it is motivating, because it’s really starting to look like an airplane! On the other hand, fitting this thing is turning into one of those multivariate problems where each little thing you need to do is affected by four other things, with all sorts of cascading effects.

But hey, progress is still happening, even if there’s a lot of rethinking on the fly going on…and in the end, the motivation is definitely beating out the fitting challenges.

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