[Rick6a]

Advances in newer kit design is nothing short of astounding based upon my comparative experience building the standard RV-6A kit. Still, in a determined effort to build the lightest RV-8 possible I am reviewing everything, especially when it comes to weight. Case in point.....the flaps. I am considering cutting in additional lightening holes into the four FL-705 ribs to shave a few grams of weight from the assembly.

Considering the loads imposed at Vfe, and also that such lightening holes generated with a Unibit would not have the stiffening ring pressed around the perimeter of the holes (such as those typically found on wing ribs), I'd appreciate input from knowlegeable forum members, especially welcoming thoughts from those with a structures/engineering background.

 

[Mel]

Rick,
In theory there should be nothing wrong with the lightening holes you propose, provided they are properly flanged. However, considering the flight loads on the flaps vs the potential weight savings, I personally wouldn't recommend it.

 

[Guy Prevost]

Rick,
In theory there should be nothing wrong with the lightening holes you propose, provided they are properly flanged. However, considering the flight loads on the flaps vs the potential weight savings, I personally wouldn't recommend it.

Rick,
I'm a mechanical engineer specializing in aero structures. I agree with Mel wholeheartedly. The holes you are proprosing are on the neutral axis for the expected loads and SHOULDN'T contribute structurally. However, there's not much weight savings to be had by putting them in there. The conservative approach is to leave things alone.

As a rule, I wouldn't make structural changes without talking to the original design team to make sure I'm not missing some part of the original design intent.

Guy