closing holes at center section

[KayS]

Hi together,

i build a 7. the instruction says to close the open holes in the center section with bolts that are there for the nose gear version. is that really necessary? can i leave them just open? i asked vans and the answer was "yes you should close them due to drawing 11..." thank you but i saw that too... any ideas if the structural integrity is affected by an open hole?

thank you...

Kay

[flion]

Yes, close them. It's not a good idea to second-guess the designer. Even John Harmon took a lot of grief before the Rocket was deemed a viable mod and, unless you are a similarly talented engineer, you probably don't want to go directly against what the manufacturer tells you. You really don't want the center section to fail; tends to ruin your day.

[apkp777]

We all know how fun it is to reach in between the spars to put the nuts on, however you have to put those bolts in. The shear loads on the center section are, in my estimation, pretty significant.

[mcencula]

If the bolts are only going through the forward half of the center section, I doubt they contribute any strength (yes I'm an engineer, no I haven't done any analysis on this). Shear loads are max at the halfway point in the web and taper off near the top and bottom. The bars at the top and the bottom will be in either tension or compression. Adding a bolt could help the compression strength of the bar depending on how tight the clearance is in the hole.

I would expect any inspector to ask about empty holes, however, and I can't see any downside, so I'd follow Van's recommendation.

FYI, I just taped the nut to the end of my scale to get them started down in there. Easy enough.