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Help, Bevel 713/counterbalance elevator skin?

grantcarruthers

Well Known Member
Can anyone give me a more complete description of this task in the right elevator construction????

I searched 713 and bevel and got no hits on the forum.

Instructions are to bevel 713/counterbalance skin inboard and aft over the understructure to get a smooth trasition.

Can't picture it so anyone have some words of wisdom.

This is for the -8 but figure most empennage are the same so posted in general, hope this is correct.

Thanks

Grant
 
Grant -

The idea is to bevel or "round" the lead counterbalance, so the 1/8" radius of the 713 skin bend isn't trying to bend around a sharp corner.

Take a look at my blog and you can see a pic from the end; showing the counterbalance wrapped in the 713 skin.

Empennage page - 4th row down - center

http://rv7builder.com
 
Thanks for the reply but I don't believe this pertains to the counter weight itself.

The instructions are: to bevel the inboard and aft edges of e-713 locally where 713 overlaps the spar and rib flanges to provide a smooth transition between the counterbalance skin and 701/elevator skin.

To me, 713 lays flat over the rib and spar flanges so

Bevel to me is shaving the underside of 713 so it doesn't ride so high over the elevator skin

This to me sounds like it would leave 713 too thin and prone to cracking.

If it means trim so 713 and 701 abut I think it would say trim instead of bevel?

Anyone???????????????????????

Thanks again.
 
Grant,

I beveled the top side of the bottom skin where it fits between the upper skin and the rib flange. This keeps the transition of the overlap fairly smooth and prevents a big "Bump" where all the pieces meet. Beveling the bottom side might create an uneven mating surface for the rib flange and I didn't want to do that because of the smaller surface area of the flange.

You don't have to take off a bunch of skin material, I left about half the thickness at the thinnest part of the edge. On the -7, there is a similar operation for the rudder counter-balance skin. I did it the same way there. Sorry I dont have a picture of the area, I didn't think it was that big a deal.

Hope this helps.
 
Grant -

sorry about the misunderstanding. Yep, you're right. It is telling you to shave a bevel on the underside of the skin - making it thin, so it transitions to the elevator skin without riding high. The same technique is used on the overlap of the wing skins.
 
They want you to put a slight bevel on the outside of the counterbalance skin. This is so when you put the main skin on top, you don't end up with an ugly bulge at the spar where they meet. Simple as that....just smooth out the transition a bit.

By the way, if you look about 1/2 down, you'll see how I riveted my stiffners. Made it a lot easier, I think.

http://www.ballofshame.com/flying/rv-7/buildLog/20060205.php

YMMV
 
Do I have this right?

34gpli9.jpg

Thinned on the edges, but not sharp.
 
34gpli9.jpg

Thinned on the edges, but not sharp.

:confused:

I'm thinking the whole portion of the counterbalance skin (E-713) where it slips underneath the elevator skin (E-701R/L) needs to be shaved down so that the E-701 will transition to the part of the tip rib assembly that extends forward past the spar without as much of a bump.

I'm at this point right now and have been mulling it over in my head all week. I think I'm going to call Van's this morning. The only picture I have from an RV8/A shows the counterbalance skin (E-713) riding over the TOP of the elevator skin (E-701R/L). Aerodynamically that sorta makes more sense to me, but it doesn't follow the instructions I have.

:confused:
 
:confused:

I'm thinking the whole portion of the counterbalance skin (E-713) where it slips underneath the elevator skin (E-701R/L) needs to be shaved down so that the E-701 will transition to the part of the tip rib assembly that extends forward past the spar without as much of a bump.

I'm at this point right now and have been mulling it over in my head all week. I think I'm going to call Van's this morning. The only picture I have from an RV8/A shows the counterbalance skin (E-713) riding over the TOP of the elevator skin (E-701R/L). Aerodynamically that sorta makes more sense to me, but it doesn't follow the instructions I have.

:confused:

What you are thinking is correct, and that is what is visible in the photo... there is a bevel on the aft edge and on the portion of the inboard edge that is underneath the elevator skin.
 
:confused:

I'm thinking the whole portion of the counterbalance skin (E-713) where it slips underneath the elevator skin (E-701R/L) needs to be shaved down so that the E-701 will transition to the part of the tip rib assembly that extends forward past the spar without as much of a bump.

I'm at this point right now and have been mulling it over in my head all week. I think I'm going to call Van's this morning. The only picture I have from an RV8/A shows the counterbalance skin (E-713) riding over the TOP of the elevator skin (E-701R/L). Aerodynamically that sorta makes more sense to me, but it doesn't follow the instructions I have.

:confused:


So, I just got off the phone with Van's. I was completely wrong! So the objective is NOT to take enough material so that the elevator skin (E-701R/L) sits near flush with the counterbalance skin (E-713). The objective is to take off the sharp outer edge of the counterbalance skin where it rides under the elevator skin. Once everything is riveted together, this sharp edge could vibrate into the elevator skin and cause cracking. So the operation is to use sandpaper (or scotchbrite wheel) to knock the sharp edge on the last 3 inches of the inboard side of the counterbalance skin and the aft end of the skin. I hope that makes sense....
 
This is why this forum is fantastic.
I had this exact same head scratching moment. A quick search and my question has been answered and am building on!!

Thank you VAF!!!
 
dcurrier I just had that same question on my -8, a quick read of the forum just solved my question too, thanks!

-Mama
 
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