Willy Nillies Cub/Savage Bobber 250

[speedbirdted]

I would suggest using basswood. It's just a little heavier but much stronger and while its abilities to suck up thin CA aren't as good as balsa it's much better than bbq skewers. If you use thin square sections it will be much easier to get flush fitting joints which by themselves are good from a structural standpoint but will also maximize the effectiveness of gussets if you choose to add any. Painted black, the square sections versus the round tubing of the full scale bobber will still look fine.

You should be really careful designing the fuselage though. Many stick built airplanes heavily rely on the covering for stiffness, and not adding that means there must be some clever geometry employed in the fuselage construction. I'tll be a little more difficult to do this and keep it light, but nowhere near impossible

 

[TooJung2Die]

It's not because you used bamboo. Bamboo is better than carbon fiber in many applications. The reason the fuselage is breaking at the glue joints is you used end-to-end butt joints. Butt joints are the weakest glue joint there is. There needs to be overlap at least four times the diameter of the bamboo when joining it to another piece. Make a notch in the balsa to insert the bamboo before gluing. Overlap the bamboo-to-bamboo joints using a scarf joint. The more area the glue has to adhere to the stronger the bond. Simple scarf joint:

That kind of glue joint is stronger than the surrounding wood. For angled joints take the right side piece in the picture, flip it over and glue it to the top of the left piece. You can also wrap the joints with thread or dental floss then coat with CA glue for a very strong glue joint. Use gussets as speedbirdted suggested too.

 

[OliverW]

It's not because you used bamboo. Bamboo is better than carbon fiber in many applications. The reason the fuselage is breaking at the glue joints is you used end-to-end butt joints. Butt joints are the weakest glue joint there is. There needs to be overlap at least four times the diameter of the bamboo when joining it to another piece. Make a notch in the balsa to insert the bamboo before gluing. Overlap the bamboo-to-bamboo joints using a scarf joint. The more area the glue has to adhere to the stronger the bond. Simple scarf joint:

View attachment 180387
That kind of glue joint is stronger than the surrounding wood. For angled joints take the right side piece in the picture, flip it over and glue it to the top of the left piece. You can also wrap the joints with thread or dental floss then coat with CA glue for a very strong glue joint. Use gussets as speedbirdted suggested too.

Since it was a skewer I cut a rounded notch into each piece so they'd fit together noice

 

[Seahunter]

I love it too. I'm trying to keep close to the scale shape while keeping it strong

I'm watching this thread with great interest. I have wanted to try this build every since I saw the first video of one on u-tube. Looked at this drawing many times and wanted to build and fly one, they showed amazing slow speed control on theirs. Hang with it, looking good!
Fred

 

[OliverW]

I'm watching this thread with great interest. I have wanted to try this build every since I saw the first video of one on u-tube. Looked at this drawing many times and wanted to build and fly one, they showed amazing slow speed control on theirs. Hang with it, looking good!
Fred

View attachment 180388

I just need to finish laying tissue down on a micro project

 

[TooJung2Die]

Since it was a skewer I cut a rounded notch into each piece so they'd fit together noice

I know you said not to look too close at the glue joints but I zoomed in on a few joints in your photo and I don't see what you just described. I see gaps. Here is one way you can make a stronger joint for the longerons with more surface for the glue.

 

[OliverW]

I know you said not to look too close at the glue joints but I zoomed in on a few joints in your photo and I don't see what you just described. I see gaps. Here is one way you can make a stronger joint for the longerons with more surface for the glue.

View attachment 180391

I fixed it on the second side. The first one was definetly weaker and I went to go replace all the wood and make it look like the other one, but found the skewers had no flex to em and just kept on snapping at the glue joints

 

[chris398mx]

I fixed it on the second side. The first one was definetly weaker and I went to go replace all the wood and make it look like the other one, but found the skewers had no flex to em and just kept on snapping at the glue joints

What if you wrapped them in thread and soaked in CA?

 

[OliverW]

What if you wrapped them in thread and soaked in CA?

I probably could get that to work, but its much faster to just make a new fuse structure and have that take me around 30 minutes.

 

[OliverW]

I've been trying to get back to this plane. I've been having to do lots of maintenance on stuff and finishing old projects. Right now I'm working on finishing a Goldberg eaglet and then I'll be finally back to this one!

 

[Deni Veras]

Seu projeto é muito legal. Onde encontro arquivos desse trabalho?

 

[TooJung2Die]

Seu projeto é muito legal. Onde encontro arquivos desse trabalho?
Your project is very cool. Where can I find archives of this work?

He is modifying a kit and there are no plans. Willy Nillies J3 Cub 250