Reinforcing wing (Kit 302 Cessna 170)

[tpwpny]

Instructions recommend reinforcing the wings with birch dowels for strength. In the case of the Cessna 170, it's a high-wing design, of course.

Since lining up the wings and maintaining dihedral are important, what’s the best way to drill holes on each side to ensure they line up? I have a Dremel tool with a fine bit… I imagine if holes don’t line up perfectly, I’ll have misaligned wings.

Apart from marking holes measured with a ruler so they align, is there any better way? (Caveat: I already covered the wings in tissue, per the instructions... seems this order not have been a good idea since instructions recommend drilling all the way into the second rib...!)

[heywooood]

in the future - I would align and stack the ribs to be drilled over the fuselage section - secure the work to a board, and drill them all at once - this way the holes are aligned perfectly on all axis...
after the wings are assembled the dowels can be secured to them..I would reinforce the fuselage receiving holes on the interior with 1/8" or thicker balsa...I would hog out the holes to make them slightly loose fitting to the dowels to allow for proper dihedral adjustment - then use a slow curing two part epoxy for strength and filler characteristics..

since you are working post wing construction I would carefully drill into the wings first - make those holes where they are best situated - insert your dowels then apply a drop of black paint to the dowel ends and use them to mark the drilling locations on the fuselage..line up the wings, tap the painted ends to the fuselage, then drill your holes...you can use a dihedral template to angle the drill if you have a drill press - or - just drill straight as possible then hog out the holes and use a two part epoxy using the dihedral guide under the wing and against the fuselage to get the angle right as it cures..

[Bill Gaylord]

Years ago I had to cut and remount a C150 wing, to correct the incidence. I would take the inner former from each wing, hold it against the mating former on the upper cabin and adjust into position. Then poke pins through the mating formers, in the front and rear of the formers. The further apart the better, for increased accuracy. Once the first one is in place, it would be used to set the other side with matched incidence. Since drilled holes tend to go off center, I'd actually glue the pin heads to the inner wing formers, creating locating dowels. Pins seem to be made from relatively soft metal also, so they could be cut shorter and resharpened with a file, before installing, so you wouldn't have an inch of pin sticking inside the cabin. Gluing a patch of balsa over the pin heads would ensure they stay in place and don't break the glue joint. The formers with the pins glued in place could then be used as the inner most former for each wing panel build, and you wouldn't be able to mix them up either, which is a good thing. I thought about doing this with my current Cub build, but the LC parts are accurate, so it shouldn't be much problem getting good wing-to-fuse alignment. With the die-cut kits, it's a different story.

Just read that the wings are covered, but I don't see why the indexing pins couldn't be installed from inside the cabin.

[tpwpny]

I tried something similar - haven't glued the wings yet but the dowels are now in place similar to the illustrated in the instructions.

I measured locations for holes with a ruler and marked the spots on each canopy mating former. I then finally realized why the instructions call for a 1/6" dowel with sharpened ends: I used a Dremel to sand the dowel ends toothpick-sharp and found that, if you twist carefully, you can poke them through the mating former just like a drill bit. After I poked them right through to the opposite side of the canopy, I pulled them out, positioned each wing against the mating former, and marked a spot on the mating wing former (through the holes) with a fine tip marker.

Then, rather than attempt to poke a dowel through a tissued wing and damage it, I drilled starter holes with a fine Dremel bit into the mating and 2nd ribs of the wings. This was like brain surgery-- one wrong move and I drill through tissue from the inside of the wing. Holding the wing up to sunlight helped... it gave me "x-ray vision" to inside the wing to see where I was drilling.

With both dowels in place, and a few adjustments to the holes with the Dremel, the wings went on nicely and (seemgingly) in line. Not perfect, but for my first model, I think I have decent wing reinforcement. (I'll check back with you once wings are glued and struts are attached...!)

Probably all more work than what was necessary, but in the future I hope Guillow's can revise their instructions to note that this reinforcement exercise should be done before tissue covering.

[Bill Gaylord]

Then, rather than attempt to poke a dowel through a tissued wing and damage it, I drilled starter holes with a fine Dremel bit into the mating and 2nd ribs of the wings. This was like brain surgery-- one wrong move and I drill through tissue from the inside of the wing. Holding the wing up to sunlight helped... it gave me "x-ray vision" to inside the wing to see where I was drilling.

The "brain surgery" brought back memories of the "adding torque rod ailerons after the build" procedure. Years ago I built a few models, thinking I could fly them RET. Not the case, but they eventually went on to be successful aileron flyers. I would sharpen a rod with a bit of a drill point, and have to guide it through the formers from the cut away aileron. You only got one chance, and they ended up wherever they did. Then the 90 degree bends had to be added in that little cutout area in the center of the wing.

[davidchoate]

I like that Spitfire wing. I love to just stick a servo on each one, but on a warbird it just seems to look like it stands out more than a high wing Cub or the like where the wingstruts hide rod and clevis. I personally like to make a one piece wing. On a high wing You leave the front of the wing Rib part attached to the fuselage where the front windshield attaches, and cut the top off above the side window, and configure it to make a center section. I am not smart enough to think of that. I copied it from a Model I built by Alien Aircraft. I also learned the hard way (I read about it after) to reduce the dihedral when adding ailerons, and make them larger than scale. I Rc converted a Dumas Aeronca Champ 30". I did it perfect, and had one of the best Pilots at My RC Club Maiden it. AS soon as he went into a turn a disasterous crash occurred. David Lewis could probably explain it better but there is an effect that has a name I do not recall that the dihedral actually makes things worse the more You try to get the plane level. I wonder how many Planes I destroyed in the last 6 years learning? I cant even count em. But I really hated that crash because if I had come across that thread or article a few years ago I would be way more ahead of where I am now. I spend a lot more time going through conversion threads on a Plane I am going to convert before I do it now.