Folding the rudder and elevator leading edges instead of rolling them?

[bruceh]

I came across something I had not seen before.

This is looking straight down along the leading edge of the rudder on this RV-6A.
The builder folded the rudder skins along the line of prepunched holes, then rolled the skins tightly.
So, the normal rounded leading edge of the rudder is open instead. No pull rivets connecting the rudder skins together at the leading edge.
Same technique was used on the elevators.
All of the control surfaces swing freely and there is no binding, but it has me scratching my head as to why they did this, and is it airworthy? Airplane has been flying for over 20 years.

Thoughts?

 

[Kyle Boatright]

I came across something I had not seen before.

<snip>

Thoughts?

No idea what the design margins are on the elevators and rudders, but leaving the leading edge open like that reduces the torsional stifness of the surfaces. By how much, and does it matter? Dunno. But I'd build it as designed.

 

[fixnflyguy]

As far as I know, there were never any prepunched skins on a -6, same as my -4 I built. Lots of unusual things have been done by builders that have worked fine for many years, but as mentioned, you take away strength in what us engineer types call a "D" section, which is extremely strong. The flaps are actually built like that somewhat, but any "per plans" deviation will be questioned by an RV savy set of eyes.

 

[HFS]

From "The Bakersfield Bunch" ...

I used to see this in some of their early (-3 & -4) airplanes - built circa mid '70's. Don't know if it was something John Harmon did for convenience, or whether Van's early (early) plans showed that as a finished condition. My -4 plans were drawn in 1980, and show the standard rolled/riveted leading edge, with no "change" note indicated.

HFS

 

[71459]

Wow. Of no structural consequence, but that's sloppy workmanship and done wrong. Maybe a small aerodynamic penalty when the rudder is swung to the right. Suggestion: take it off and fix it.

 

[PhatRV]

I've seen Mooney elevator leading edges that were bent like in the picture. There was no rivet to fasten the two edges together

 

[bruceh]

Wow. Of no structural consequence, but that's sloppy workmanship and done wrong. Maybe a small aerodynamic penalty when the rudder is swung to the right. Suggestion: take it off and fix it.

You wouldn't normally even notice this unless you start looking down through the access cut outs for the rod end bearings.
I didn't see any aerodynamic issues at full deflection.

 

[I-TERA]

changing the torsional stiffness of the rudder ( no D shape torsion box) changes the torsional resonance frequency.
Flutter speed change is the direct consequence. I hope you newer will discover your flutter limit speed , may be lower as you imagin……

 

[rvbuilder2002]

Wow. Of no structural consequence, but that's sloppy workmanship and done wrong. Maybe a small aerodynamic penalty when the rudder is swung to the right. Suggestion: take it off and fix it.

It absolutely could be a structural consequence, but as already mentioned, the amount of influence is unknown without testing.
Closing the leading edge will add some level of torsional rigidity.
It may not have a huge influence because of the opening for the middle hing point, but it would have some influence.

 

[Snowflake]

As far as I know, there were never any prepunched skins on a -6, same as my -4 I built.

Early -6 kits were not, but later -6 kits were. Not final size, but pre-punched. Not sure when the changeover occurred.

 

[Sam Buchanan]

Early -6 kits were not, but later -6 kits were. Not final size, but pre-punched. Not sure when the changeover occurred.

My October 1997 RV-6 kit had pre-punched tail and wing skins. The punched skins were actually a bit more labor intensive than non-prepunched due to having to line up sub-structure with the punched skin holes.

 

[JonJay]

For clarity, PP part numbers meant “Pre-punched”, not to be confused with “Match drilled” like the new kits.. Just the skin was punched.
Totally agree with Sam. Mine is the same vintage. You had to draw center lines on ribs and such and push them around to line up the holes for drilling.