Rudder stiffeners bowed

[RVG8tor]

I did a search and couldn't find this subject. I am starting the rudder and have cut out the stiffeners to length. But each one has a slight bow to it. reading ahead it seems you check the rudder skin for straightness. Are the bow there on purpose to counter the skin, will the skin take out he bow? If seem the skin is thinner and will end to follow the bow in the stiffeners. How would one flaten the stiffeners, maybe mine are bad and I need new one? what I think is that the bow is from the hole punching machine. Thanks if advance for any help.

Would heating the stiffeners make them flatten out.

[Paul Thomas]

Finish cutting them first, you'll add some bow or twist, specially if you do it by hand. Even dimpling gives a slight bend. Straightening them out in not hard and doesn't require heating.

[borislav]

Originally Posted by RVG8tor

I am starting the rudder and have cut out the stiffeners to length. But each one has a slight bow to it. reading ahead it seems you check the rudder skin for straightness. Are the bow there on purpose to counter the skin, will the skin take out he bow? If seem the skin is thinner and will end to follow the bow in the stiffeners.

Is the -8 rudder matched-hole these days? If yes, you don't need to worry - when you cleco/rivet the stiffeners on, they'll straighten out. (I had the same issue on a -7 rudder and asked Van's about it).

If you don't have matched holes, you have to be careful to have the stiffener flat when you drill it to the skin. Once it's rivetted, it won't be able to bow again.

[RVG8tor]

Originally Posted by borislav

Is the -8 rudder matched-hole these days? If yes, you don't need to worry - when you cleco/rivet the stiffeners on, they'll straighten out. (I had the same issue on a -7 rudder and asked Van's about it).

If you don't have matched holes, you have to be careful to have the stiffener flat when you drill it to the skin. Once it's rivetted, it won't be able to bow again.

My kit is matched hole so I guess I am OK. I just thought the skin was so thin that it might bend instead of the stiffeners bending. I think the other post is correct in that the cutting and dimpling might help straighten things out. I only asked the question in that the instructions have you measure the rudder for flatness after installing the stiffeners, so I thought if I was starting out with less than flat stiffened then I might run into trouble. We will see, so far I am really enjoying the build process. Thanks for all the help VAF.