Sioux Bipe Contest Build

[FlyingTyger]

Willy Nillies has been hosting a wing kit build contest yearly. Here is a link to the announcement on their Facebook group: Linky
You may need to be a member of the group to view, but basically, the idea is to build a design of your own or a modified kit using at minimum 3 original WN ribs. The finished plane must be under 250g and you must provide proof of flight.

For this year's entry, I decided to build a biplane version of the Sioux. The inspiration coming from this random vintage RC image I found Pinterest.

 

[FlyingTyger]

First thing to figure out is the placement of the bottom wing. I drew a centerline on my bench then started sketching things out.

With the wing cutout in place, I now had to relocate the servo tray since they would've interfered with the bottom wing.

Once I decided where everything fit, I glued in some coffee stirrers so I could remove the wire rods until after covering.

 

[FlyingTyger]

With the internals figured out, the top of the fuse was sheeted.

Now the fuse sits until I have wings.

 

[FlyingTyger]

Wings!
I framed up the first wing half but realized that I had to make another decision before going much further.

Bottom wing span. Should it match the top or be a bit shorter?

I ultimately decided to do both wings at full span and got all four panels framed up.

Jigged for dihedral, then top sheeting applied.

 

[FlyingTyger]

Bottom wing was notched for the fuse. This opening will be cleaned up later and faced off with balsa.

Quick test fit.

First complete test fit.

 

[bisco]

looking good!

 

[MZ250Ben]

I love the cow pin holder. I'm just about to start my first balsa build in over a decade, so I'm trolling this page for hints. My old method was corrugated/plans/wax paper and pins to hold in place. What's your covering technique? I remember using diluted white glue to fix the tissue then shrinking it with alcohol spray. Is there anything new besides "dope" for fuel/moisture proofing? I'm doing the Guillows 16" F6F hellcat for 3 channel rc, so weight is a big factor.

 

[FlyingTyger]

I love the cow pin holder. I'm just about to start my first balsa build in over a decade, so I'm trolling this page for hints. My old method was corrugated/plans/wax paper and pins to hold in place. What's your covering technique? I remember using diluted white glue to fix the tissue then shrinking it with alcohol spray. Is there anything new besides "dope" for fuel/moisture proofing? I'm doing the Guillows 16" F6F hellcat for 3 channel rc, so weight is a big factor.

For my building board, I have a layer of sound insulation board that I pin the plans to. I cover the plans with clear plastic painters drop cloth. The drop cloths look kinda milkish in the package, but are clear enough when you lay them directly over the plans. And CA doesn't stick to them.

For covering something like a small Guillows kit, the tissue is still probably your best option. I too remember using a a dilluted glue mix to "dope" the tissue after tightening. Nowadays I'd probably seal the tissue with Polycrylic after shrinking. I know some have used Doculam as a lightweight iron-on covering. I have had mixed results getting paint to stick to it, so it wouldn't be my first pick.

I have found the Guillows models to be high performance machines when done. They tend to be a bit heavy for their size but that's not to say they can't make for a nice model. I did one (Beaver) successfully. It was a little too fast for indoor flying, but flew well outside.

There is a huge list of conversions over on RCGroups. I suggest you do some research over there. Linky

 

[MZ250Ben]

Thanks for the feedback, sorry mine took so long. My teeny tiny servos finally arrived so I got a jump on it finally. All up so far, battery included, I'm at 64ish grams. Still needs stringers, covering, cowling, wheels and the control surfaces/hardware. Gonna be tough to keep it below 4 oz, but I can't guess at this point, been a while since I've had to count calories. I am going to use a smaller battery also, it's not in my hands yet but should save me 5-7 grams. I forgot how much fun these were to build.

 

[FlyingTyger]

Thanks for the feedback, sorry mine took so long. My teeny tiny servos finally arrived so I got a jump on it finally. All up so far, battery included, I'm at 64ish grams. Still needs stringers, covering, cowling, wheels and the control surfaces/hardware. Gonna be tough to keep it below 4 oz, but I can't guess at this point, been a while since I've had to count calories. I am going to use a smaller battery also, it's not in my hands yet but should save me 5-7 grams. I forgot how much fun these were to build. View attachment 248842

Looks great!