Fixing wing root gaps- a cautionary tale

If you’ve built the AMT P-40 kits, you know they’re not too bad. They are affordable, everywhere, and cover the range of models from the P-40E onward.

In the few I’ve built, there is always a pretty significant wing root gap. In my latest build, I thought I had come up with a good way to fix it.

I started by adding shims to the inside edges of the top wing pieces. Test fitting showed this should work pretty good, and would allow the wingtips to drawn up a bit by a rubber band in order to add the needed dihedral.

But as I test fitted further, I noticed the lower cowl piece was a bit too wide for the area of the fuselage where it was supposed to fit. “No problem” I thought. “I’ll just add a fuselage spreader!” So I cut a piece of sprue that was a bit too wide, and then sanded it down until test fitting showed a perfect fit. I mated the lower wings on to test things, and they virtually snapped into place. Perfect!

Not quite….

I had forgotten to account for the fact that the fuselage spreader should have been added before I added the wing shims. But because I had already test fitted that, it didn’t occur to me that any problems would result.

So I added the wings on, glued them in place, and used a rubber band to pull the wings up a bit. Setting it aside to dry, I was quite happy with myself. Even posted to Facebook about it.

Once it dried, I pull the rubber band away, and saw-  no dihedral. Yes, the rubber band did draw the wings up- but what I had seen was wing flex- not actual dihedral.

So now I have a reasonably nice P-40 with flat wings. Great.

But, lesson learned.

  • Spread the fuselage first
  • Test fit the wings
  • Hold the fuselage from above, and press on the wings from below as close to the wing root as possible to see an how much dihedral you’ll get
  • Then, if needed, add shims without gluing and test fit some more
  • Once you have it correct, glue the shims in place
  • Test again and make any needed adjustments.

Now I know. 🙂

 

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