tbzep

Just finished my Ultimate FF. I've got the plane together and ready to install electronics but notice that the bottom wing isn't rock solid in the saddle even with the upper wing attached to help brace it. I assume this isn't normal.

I've read somewhere about using epoxy or some type of silicone to custom shape the wing saddle. What type of silicone and advice do you have?

Tim

PaulSwany

My Feedback: (45)

I heard of that method before... you mix some epoxy with micro balloons and coat the wing saddle with the slurry. Then you mount the wing with a piece of wax paper in between.... You can smooth it out alittle with it starts to get tacky. Just use a little water on your finger tip. After it dries, you have a perfect wing saddle formed to fit your specific wing airfoil.

tbzep

I don't have any microballoons, and I don't have access to a hobby shop due to location, work hours, and current weekend commitments.

Other than weight savings, microballoons wouldn't have any other effect, would it?

Anybody use clear silicone caulk or some other substance that I could obtain locally that would be easier and cleaner to work with than epoxy?

Tim

PaulSwany

My Feedback: (45)

You're right.. adding the micro balloons is only for weight... I've heard you can add some modeling puddy instead.. anything to reduce the weight... I imagine you could add some chopped up foam to realize the same weight savings.... Or just use the epoxy straight if weight isn't an issue.

I've used silicone on wing saddles before... It has a tendency to not adhear well to the monocote

rcman-RCU

My Feedback: (31)

The standard way to do this is:

1. Wrap the wing with saran wrap where it contacts the wing saddle.

2. Lay a bead of clear silicone caulk in the wing saddle. Make the bead the right size to fill the gap and ooze out the sides a ways.

3. Lay the wing in the saddle and secure it. Let the excess silicon ooze out the sides of the gap. Do not touch it! You will just smear it all over the covering.

4. After it dries, remove the wing and saran wrap. Then us a sharp razor blade to cut the dry silicone flush with the sides of the fuselage. In this opertion, you trim off the silicone that has oozed out past the gap.

tbzep

I wonder if I very lightly scuffed the Ultracote with fine sandpaper the silicone would adhere better. I don't plan to remove the wing, but I'd like to keep the option if needed.
I guess I'll try the silicone first, and if it doesn't work as well as I like, I can cut the stuff away and use epoxy.

Tim

danielfd

i have a sig ultimate profile and the same happened just fill it with epoxy