rivets and swiss cheese

[Darick]

I was speaking recently with an older pilot (I have to be careful how I word that, as I'm 64) with lots of experience with tube and fabric construction, but little experience with our riveted Sonex (and RV's, Zeniths, etc.) construction. Not having much faith in pulled rivets, he asked if I was going to fill up all those rivet holes in the wings with body putty so the wing wouldn't be like a piece of swiss cheese. Well yes I thought to myself, you can see a speck of light through some pulled rivets but so its so small it would have to be measured in microns.

Up to this point, I hadn't reality thought about it, but knowing John Monnett's engineering background and experience I knew this had to be a silly question. Still, I wanted to go back to this good intentioned pilot with an answer.

Turning to the wing plans page, I quickly added up the number of rivets on a wing. With micrometer in hand, I measured the diameter of the rivet stud and the diameter through which it is pulled. Then finding the difference in areas and multiplying by the number of rivets in one wing, I came up with less than one half square inch! And I'm certain it has to be less than that as the rivet body and stud relationship changes as the rivet is deformed. Well needless to say, it's less than negligible…not even worth the time to think about it. But it was an interesting exercise anyways.

When I tell this fellow the good news that my wing is much better than a piece of swiss cheese, I'll remind him about all the ill fitting inspection holes in his 40 year old Cessna. :-)

[tonyr]

Turning to the wing plans page, I quickly added up the number of rivets on a wing. With micrometer in hand, I measured the diameter of the rivet stud and the diameter through which it is pulled. Then finding the difference in areas and multiplying by the number of rivets in one wing, I came up with less than one half square inch! And I'm certain it has to be less than that as the rivet body and stud relationship changes as the rivet is deformed. Well needless to say, it's less than negligible…not even worth the time to think about it. But it was an interesting exercise anyways.

I doth think you have way too much time on your somewhat idle hands... get back to building !! lol

[Sonex1517]

Sounds like the EAA chapter I *used to be* a member of....

They held a Sonex fly in, and proceeded to bash the type. Including ill informed words about the pulled rivets.

Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

[Bryan Cotton]

I am sure Cessna built to a standard. I am sure it was much less of a standard than the average slightly obsessed homebuilder. Cessna was trying to turn a profit and the homebuilder is in it for pride. In the '46 Cessna I was restoring I found some ugly Cessna work and a lot more ugly rework. I could never earn my living as an A&P as I would be too slow to turn a profit.

I actually like solid rivets better than pops - except as the airframe is flying together under the hands of my 12 year old. The Monnetts had a vision of a design that would let the average person build an airplane, both financially and with respect to workmanship skills. I don't know the statistics for % of Sonex completions but it is probably pretty good.

If we were to talk absolutes, the Waiex is not my ultimate airplane. Look at the numbers and RV's are faster, roomier and have more payload. I still want a Pitts when I grownup too. But, it is an airplane that is pretty cool, I can afford it, and its mission fits the bill. A huge plus is that it is an easy project that I can build with my son. I voted Waiex with my dollars and my time.