Rivet Question for Repeat Offenders

[N223JH]

I'm flying a 6A and thinking about building a 12 as an amateur-built experimental. Would like to flush-rivet the 12 but Vans says the skins on the 12, particularly the wings will require many pulled rivets. If I remember correctly, my slow-build 6A required a few pulled rivets in the empennage and wings but many of the pulled rivet locations could be circumvented with planning and homemade tools.

I don't have the 12 plans, so would appreciate feedback from 12 builders on the "reachability" factor for getting the bucking bar behind the skins. Specifics on estimated percentage of pulled rivets needed by section would be especially appreciated.

BTW, I'm not looking to bust the LSA speed regs, it's just a matter of esthetics and...gosh, I've got this C-frame and all these neat dimple dies and rivet sets rusting away in my shop... TIA Jim in San Antonio

 

[Geico266]

IMHO, I think you could get at most if not all of the rivets to buck them, just like any other Van's plane, except for the wing tips. The wing tip close outs are gonna be the real challenge as they are all metal. The leading edges of wing walk areas are flush pulled rivets, so maybe you could use them in areas that get tough? You could use flush pulled rivets in any unaccessable areas. If you could adapt / build a set of fiberglass wing tips to it you would be better off. The design of the wing ribs (lightening holes) is pretty much the same as other models. The VS & elevator may give you some challenges, as they all do. The fuse & tailcone would be easy for a "tunnel rat". FYI, all / most of the pre-drill holes will require #4 rivets, but these will match the flush pulled rivets when you have to use them.



I think a flush rivet-12 would be pretty cool, lighter, and faster.

What engine are you thinking about? IO-390?

Good luck in your decision making. Keep us informed!

 

[tim.randles]

At the Thursday morning "Van's Aircraft Design" forum at Oshkosh this very issue was brought up by Ken Krueger. If I'm remembering correctly it was during a session where he was talking about common questions that they get from folks where the questioner is failing to fully consider the ramifications of what they're considering. A brief paraphrasing of what Ken said:

1) The -12 was designed with pull-rivets in mind and as such there are many places you will not be able to get into with a bucking bar
2) Van's back of the envelope calculations show that there would be at most a 1 or 2 knot increase in speed. At LSA speeds the parasitic drag difference between the pulled rivet heads and flush rivets is negligible.
3) There are other issues we can't get into with the limited time we have here.

I'm probably forgetting a few other points that were made. It seemed obvious to me that Ken and Van get this query quite often and that there is no benefit to using flush rivets on the -12.

 

[flion]

Just curious, but what would that do to the S-LSA status? 'Course, it should still be E-LSA but I was just wondering how strict the requirements are? Mel?

 

[Mel]

Not sure I understand the question

Just curious, but what would that do to the S-LSA status? 'Course, it should still be E-LSA but I was just wondering how strict the requirements are? Mel?

Van's is not offering S-LSA. If you deviate from the plans without written approval from Van's, the aircraft will not qualify as E-LSA. It would have to built as amateur-built.

 

[rbibb]

Why bother?

The RV-12 is a great sport trainer and would not gain much if anything from going to all the trouble to flush rivet it. If you want to flush rivet a plane build a -4, -6, -8....

The pre-punched holes might even be too large of -3 rivets requiring you to go to -4.

Of course you and do anything you want on an experimental plan but some thing just make no sense IMHO.

 

[rvbuilder2002]

Something not yet mentioned...

Why bother?

The RV-12 is a great sport trainer and would not gain much if anything from going to all the trouble to flush rivet it. If you want to flush rivet a plane build a -4, -6, -8....

The pre-punched holes might even be too large of -3 rivets requiring you to go to -4.

Of course you and do anything you want on an experimental plan but some thing just make no sense IMHO.

The prepunch holes in the exterior skins are all sized for -4 rivets.

Most builders would find it challenging to drive 1/8 inch flush rivets on .020 skins being attached to ribs and bulkheads that are also .020. It may actually look worse in some cases than just using the blind rivets.

 

[N223JH]

Thanks to all for your input, including those who think the idea "makes no sense." Indeed, flush riveting may be problematic as Scott points out but if practicing with -4's .020 on .020 yields good results, it may be worthwhile. Note that esthetics is the only consideration; we're not looking for speed. And yes, it would be E-AB with builder proof of AC qualifying as LSA and flown no-medical by currently-certificated pilot.

 

[flion]

Van's is not offering S-LSA. If you deviate from the plans without written approval from Van's, the aircraft will not qualify as E-LSA. It would have to built as amateur-built.

Thanks, I asked the question wrong but you answered the question I meant to ask.