Warped Tail Feathers

[TexMechsRobot]

So I built a small rubber powered FF from plans and wound up with a warped horizontal stab when everything dried. I'm a little new at this and I am unsure how to straighten it out. Any suggestions?

 

[hackofalltrades]

Perhaps spray the area lightly with a spray bottle set to mist, then hold the stab in a position just a little beyond where you want it, and let dry. Should work.

 

[TexMechsRobot]

Perhaps spray the area lightly with a spray bottle set to mist, then hold the stab in a position just a little beyond where you want it, and let dry. Should work.

Thanks. This was my initial thought as well so it's nice to see that I was on the right track! Would it help if I sprayed with windex instead of just plain water?

 

[roversgonemad]

I use isopropyl alcohol it seems to shrink the tissue slower.

 

[hackofalltrades]

Thanks. This was my initial thought as well so it's nice to see that I was on the right track! Would it help if I sprayed with windex instead of just plain water?

I think using the isopropyl or denatured alcohol as the above comment stated would be the best way. Evaporates much faster too.

 

[TexMechsRobot]

Watered down or straight 70% or so from the bottle?

 

[hackofalltrades]

I think you'd be fine straight from the bottle. Just don't soak it, and maybe try on an inconspicuous area first.

 

[TexMechsRobot]

I'll try it tonight when i get home and post the results. Thanks for the suggestions!

 

[hackofalltrades]

Glad I could help!

 

[TexMechsRobot]

Soooo....it turns out I actually don't have any isopropyl at home lol. Windex it is!

 

[hackofalltrades]

Hope it works for ya!

 

[roversgonemad]

Windex can be iffy because the ammonia can affect the balsa. Unless I'm forming pieces, I don't typically use windex. If your balsa is doped well it won't matter, but if you didn't dope it, I'd be concerned about the ammonia softening things. It firms back up when dry, but it definitely affects the wood.

 

[TexMechsRobot]

It definitely softened the wood which is kind of what I was going for anyway. I kept the tail in a flat form overnight and it seems to have straightened out nicely. We'll see what happens when I let it sit out of the form for a while.

 

[TexMechsRobot]

Within 30 minutes of removing it from the form after leaving it in there for over 12 hours, it started warping back to the original image.

I let it warp to see how far it would go and it basically went back to where it started. Later, I twisted the surface with my hands past the zero point and it straightened out again. I imagine that given an hour or so, it'll twist back to the warped position but I haven't checked on it.

What it tells me is that if/when I go fly it, I'll just need to give the surface a twist before flying and I should be fine. It isn't a competition plane or anything close to it so I'm fine with it as a fun flyer

Thanks for the help everyone!

 

[roversgonemad]

I recommend twisting it past where you want it, let it dry in that position, and then see where it ends up.

 

[FlyingMonkey]

What material did you use to cover the surfaces?

 

[FAI-F1D]

Warped tail surfaces won't stop it from flying. Use small paper trim tabs as needed to correct any rolling tendencies and make sure the net effect is to provide the desired stab incidence and rudder trim.

In the future, preshrink your tissue so this doesn't become an issue on such light models.

 

[roversgonemad]

Warped tail surfaces won't stop it from flying. Use small paper trim tabs as needed to correct any rolling tendencies and make sure the net effect is to provide the desired stab incidence and rudder trim.

In the future, preshrink your tissue so this doesn't become an issue on such light models.

Listen to this guy! He KNOWS stick and tissue!

 

[Guy123]

So yeah, either pre-shrink, or you can make sure to tag the model down into place immediately after spraying so that it physically cannot warp when drying - this works for me.