Rudder Stiffeners?

[GTechRV]

So, I dive into the rudder assembly (HS & VS done, pics to come) and unwrap all my stiffeners and start matching them up. Uh... that was a mistake. After looking at the plans and hole spacings, I see that each stiffener has unique hole spacing (ie A-G). What I've come to find however is that all the stiffeners Vans sent me have the exact same spacing (A's) and they all only line up with the lower-most rudder skin holes. Is there something I'm missing here or do I need a new set of stiffeners from Vans?

Hmm. I guess some pics would be nice, but I'm totally slacking lately.

OOh... and on a side note, my maiden solo flight was this past Friday! I was so nervous but it went great. I actually have video of that here:
https://ryan.crawford.com/yjfc/
(Three takeoffs and landings - a video for each)

 

[rv7boy]

Stop, take a deep breath...and read the prints.

Ryan,
It's been over 3 years since I rivetted my rudder stiffeners, but IIRC the rudder stiffeners are "opposite hand" on the left side versus the right side. IOW, one side has angle legs on top and the opposing side has angle legs on bottom so there will be no interference when the two rudder skins come together. This brief description probably doesn't make sense, but I believe there is detail in the prints that shows this.
You might also do a search in this forum, as I believe it was discussed a few years back in a thread. Update: Here's one thread from a quick search...there may be others...

http://www.vansairforce.com/community/showthread.php?t=14266&highlight=stiffener


Hope this helps.
Don
Also an Engineer but I'm from TnTECH not GTech!
I also don't claim to be a He**uva Engineer!
I also assume you are building a 7/8/9 rudder. You didn't say. If you're building a 3, 4, 6 or 10, I have absolutely no idea!

 

[NewGuy]

The Stiffeners Really Do Fit!

...that all the stiffeners Vans sent me have the exact same spacing (A's) and they all only line up with the lower-most rudder skin holes. Is there something I'm missing here or do I need a new set of stiffeners from Vans?

Ryan,

I went thru this same issue Sunday afternoon. Line up the first hole in the stiffener past the cutout in the bend on the stiffener with the first hole from the aft edge of the right skin or the front edge of the left skin. The holes should line up. If not, rotate it around until it does. It fits. I tried both skins and they fit. I went thru the same issue.

Supposedly, the stiffener leg is on the bottom on the right skin and on the top on the left skin. I don't know where this is plainly stated- it's really hard to see in the plans and there is nothing in the text- but, I've had several tell me that's correct.

My HS is done and the VS is complete except for final riveting. I'm waiting to install the bullet camera and run the wiring before I button it up for good.

Ken Korenek
Arlington, Texas

 

[GTechRV]

Yep, I understand that the stiffener flanges between the two skins shouldn't line up. I'm just wondering if the hole spacings in the stiffeners should all be the same. I've cut the stiffeners in half and separated them into two groups, and when I line the factory edge of each group up with each other, all the holes align. Looking at other posts though, it looks like I may just need to tinker with offsetting them until they line up.
Thanks.

Oh... and also Don, I don't necessarily claim to be a helluva engineer either. Its just our fight song. "I'm a ramblin wreck from Georgia Tech and a helluva engineer"

 

[morlino]

I'm just wondering if the hole spacings in the stiffeners should all be the same. I've cut the stiffeners in half and separated them into two groups, and when I line the factory edge of each group up with each other, all the holes align

Here's a pic if it helps...

I don't remember if it is the left or right skin and I don't have the plans in front of me but it is the side with the 90* bend on the leading edge. And the stiffener flanges are on the top on this side.
I remember when I did this, I initially wanted to to trim the excess length of off the wrong side of the stiffeners and I could not get the holes to line up. I guess this means I had the left side stiffeners on the right side skin, or they were upside-down or something. I distinctly remember flipping them around a few times and going from left skin to right skin with one of the bottom-most stiffeners until the holes lined up correctly. Once you get one, the rest are easy.

 

[jdeas]

Flip them a few more times before you cut

I was warned by someone not so lucky that it is possible to cut these wrong. Not sure if that's true but it put the fear into me. I marked mine up with a blue marker as I check the holes until I found a combination that worked.
Take some more time before you cut to ID the finished stiffeners with a marker and I bet you will find a combination that works.

 

[GTechRV]

Yep, I got all the stiffeners lined up and clecoed. The plans for the rudder label each stiffener a different letter which led me to believe that each stiffener might be different. Van's assured me that they ARE and SHOULD BE all the same. Just takes a bit of playing around with the alignment. Hopefully clecoing and marking before cutting should reduce the possibility of cutting them wrong.

Thanks!

 

[AF_Alan]

Hole pattern changes

The hole pattern is the same for all the stiffeners but I found that the spacing changes very slightly at about the tenth hole from the trailing edge.

Trim to length from the leading edge of stiffener only. I bungled one of the long tapers (trailing ends) so recut the stiffener back one hole space intending to use it as a shorter stiffener. That's when I found the hole spacing changes toward the blunt end.

Alan
Wright-Patterson AFB, OH
-9A tail

 

[Flying Scotsman]

I *just* made these this weekend. If you do what they say, it works perfectly.

All of the stiffeners start out exactly the same.

Pick a skin, any skin, and begin at the bottom. Put the stiffener on the skin, with the cut-down angle piece on the aft end. Looks good, right?

Now, just work your way up the skin, putting the stiffeners on so that the cut-down (basically flat) end is always at the aftmost hole.

The *forward* part will stick out past the skin a successively longer amount as you work your way up the skin (it can *only* do that, after all). All you have to do is mark where to cut it to keep it a small fraction of inch away from the spar, and that's that. (I put the spar on first, marked a line on the skin, removed the spar and the laid down the stiffeners, then marked them about 1/16" aft of that line and cut them).

Do the same thing on the other skin. The flange will, of necessity borne of geometry, be opposite to the one you just did (if it was up, this one will be down and vice-versa).

Once you see it, it will be very obvious. BUT...make sure you are only trimming from the FORWARD end of the stiffeners...if you find yourself thinking "Hmmm...I need to shorten this up by taking more off of the tapered end", you're doing something backwards.

And...make sure you're putting the stiffeners on the *inside* of the skin. Pretty obvious on the one skin, as it has a flange on the leading edge, but the other one doesn't. I could see where one could get messed up on that one and end up with them backwards or somethine.

Hope this helps!