More joiner madness

Not really much to report over the last few days.  I've had to do some traveling for work, but I did manage to get the joiner boxes all buttoned up and everything has aligned well.  I also discovered that with the longer joiner rods in the wings combined with a little bend introduced into the rod, will hold the wings together very tightly and will probably eliminate the need for any fastening system.

Tips and joiners

Today I made some good progress.  After a nice brisk 34 mile ride on the bike (that make 120 miles this week), I started working on the wings again.  I wanted to get the tips and wing joiners done before I started sheeting, so that's what I worked on.

First, the tips.  The plans say to use bent bamboo.  As luck would have it, I'm fresh out of bamboo.  I could have laminated and steam bent some strip spruce, but I wanted more surface area to glue the wing sheeting to, and I want the tips to be a bit more sturdy.  So instead of the thin edge, I went with light weight sheet balsa 3/16" thick.  In order to get the plan image on the wood, I used the Acetone transfer method, and viola, a perfect reverse image.  Stack to pieces of wood together, take it to the bandsaw, and out pops two tips.  As you can see in the pic, I also cut slots for the spars.

Also, I created my joiner ribs by cutting out 1/16" ply ribs matching the rib #1 profile then gluing sheet 1/8" balsa to the backsides and sanding to shape.  I took those assemblies, marked out the slots for the spars and leading edge, and attached them to the wing pieces.

Then came the joiners.  I've decided to go with two 3/16" steel rods with brass receivers.  I could have gone with cf rods, but this is what I have on hand and I'm a big believer in keeping momentum going.  Will they be strong enough?  I think so unless I decide to do ground loops.

I put the brass receivers in the gull side of the wing, 2 bays deep.  Then I put the rods in the tips panels also two bays deep.  I probably could have gotten away with only one bay, but a little extra strength doesn't hurt the weight too much.  First, I measured my hole spacings and used my hand drill to make the holes.  The I dry assembled everything to make sure it all lined up.  When I was happy with the fit, I built joiner boxes around the rods using hard balsa and 1/64" ply caps and used 60 minute epoxy to hold it all together.  I kept the wings joined together with clamps to ensure that the rods and receivers stay lined up.  Since the receivers aren't attached yet, I can still tweak those a bit, but I like doing my wing joiners this way to ensure the best joint possible.

Tomorrow night, the other wing!

Starting the wings

That pesky thing called work has gotten in my way the past few days, but I have managed to get some things done.  I made the main and secondary spars for the right wing half using 3/32" hard balsa then made sure every rib joint was tight as a drum with a complete dry fit assembly first.  Then came the Tightbond, some weights along the trailing edge to make sure it stayed straight and level, and voila, a new right wing half.  Obviously, I need to add a lot more wood to the picture, but you get the drift.

I also managed to cut 1/16" ply for the wing joiner ribs, but I will wait until I get to the point where I can do alignment of the wing halves before installing the joiner system and end ribs.

The gull is framed

I'll admit.  This is the part of the build that most intimidated me, and it feels really good to be through most of it.  I like to do the hardest things first, but I imagine the fuselage will throw some curves at me too.

below is a series of shots of how I assembled each gull half.  After flying the Playboy today with fellow clubmates at the sailplane field, I was anxious to get back and glue this thing up.

First, the crappy picture.  I should have gotten the tripod out, but you'll get the drift.  In order to make sure I had the main spar square to the subspar, and straight to the rest of the assembly before I screwed down the bases, I got out the laser beam and aligned everything with the main spar.

Then I added measurements to the drawing so I could make sure each individual rib was lined up correctly.  First, I drew a line under the gull on the plans from the root to 7" directly below the tip joint.  Then I measured straight down from the bottom edge of the spar to the line, and added 1/8".  This addition of 1/8" is to make up for the up-sweep from the bottom of the rib(spar) to the leading edge groove.  Then as I assembled the ribs, I measured each one so it matched the plans.  At the rear, I used the spar template to make sure the trailing edge tips stayed in alignment.  You can see the results below on the starboard gull assembly.

Then came the leading edges.  These stacked assemblies weren't holding their shape very well, and I needed them to be dead on because I didn't want to add any stress to the gull assembly as I was putting it together.  What I found was that my heat gun did a great job of allowing me to bend a little at a time and get the leading edges fit perfectly.

And finally, a mockup of the gull assembly!

The jig is up!

I also started building a jig to put together the Gull.  It will be built on the jig and I'll try to get everything nice and even, and so far the dry fit is coming out nice and straight.  The pieces are coming together like it was laser cut!  Once I get it positioned on the drywall, I'll screw it down and start gluing.

Leading edge

The plans call for a 1/8x3/8" leading edge, but of course it needs to follow that wicked gull curve.  So instead of one piece, I decided to laminate 3 pieces of 1/8" sq. bass stock.  First I used the spars to cut a pattern in two slabs of foam board and used spray adhesive to stick them together.  I fastened them down to my drywall building board.  Then I steamed all 3 pieces for a short while - just enough to get them flexible.  I glued the edges, and pinned them against the foam board.  These should make for a nice leading edge.

Spars take 2

I made some pretty good progress today.  I figured out my slot cutting for the ribs, created a jig for the assembly, and also started on the leading edges.

First, the rear spars.  I used the main spars as the template to draw the rears, but since the rears are also narrower, I had to reduce the width to 3/4".  I also had to transfer the slot marks, and you can see how I did that in the following pics:

From there, I took all 4 spars out into the garage and setup my 4.5" grinder with a carbide cutoff wheel.  Yes, the same wheel that helped me create a new exhaust for the Porsche can cut nice clean 1/16" slots too!  Here you can see the table jig I setup to feed the spar nice and straight.

Spars

Not much to report tonight.  I got the forward spars cut out of 1/8" 5 layer plywood, but I have stalled on the rib slots.  The micro-table saw I have cuts a kerf of 3/32" and the ribs are 1/16", so there is too much slop for me.  I need to find a different way to cut the slots, or find a thinner blade, so this could be a couple of days before I get the spar slots cut.

Here are some pictures:

The ribs are born

Tonight I finished the remaining ribs, well almost.  I still need to cut the spar slots, but that will have to wait until I get the spars cut.

I used the tried and true method of spray adhesive, a modeler's best friend.  I have a special wall in my workshop that is used as the backdrop for things the get sprayed with 3M77.  The wall has enough stickem on it to hold balsa wood now.  So I cut enough blanks to make a pair for each sized rib.  I stuck each pair to the wall, lightly sprayed them with 3M77, and attached the paper rib template.  Then I stuck that blank to the other blank, and bingo, we have a stacked pair ready to cut out.

Then I took a new x-acto knife blade and started cutting around the lines making sure to stay on the outside of the lines.  Then I trued each stack up with sandpaper, and the ribs are finished.

Tomorrow, the SPARS!

Balsa dust

Tonight I realized again why I should have bought that 10" sanding disk by now....

I got the plans copied today, and started cutting them apart tonight.  I decided that the first task should be the wings.  The wings are in 3 pieces - a center section which makes up the gull, and two outboard plug-in tips.  The center section is made of 32, #1 root ribs including a couple of #1 ribs as the first set on the outboard panels.  I decided that I'll be making the two inboard root ribs, and the outboard joint ribs out of 1/16" ply for strength and durability, which means I only needed to cut 26 balsa ribs out of 1/16" stock.

I had good rib stock on hand, so I first cut 26, 1.25x9.5 inch blanks, then cut the #1 rib pattern out of the plans and attached to the top blank using 3M77.  I stacked the wood tightly, took it to the drill press, and bored two holes that I could bolt through.  Then I took the stack to the band saw and cut the pattern down to within about 1/16" of the rib outline.  I also had to make a jig to fit under the stack and accept the through bolts so it would ride flat on the band saw table.  From there, it was lots of sanding, checking with a square, and more sanding until they were perfect.

This was my very first stacked rib project, and I think they turned out pretty good.  I still need to cut the spar notches, but I'm going to tackle the other ribs tomorrow night then do all of the notches at the same time.  The next set of ribs will be more time consuming, but I only need to make two of each so the sanding part will be easier.

Plans and wood

Every good scratch build starts with a set of plans and some wood.  Well, we sort of have both covered now.  The plans came from Eut, and I did a little touch up work on some of the lines that had been faded.  Nothing serious, just a little touch up with a  pencil.  Then comes the studying....what I love most about these old plans is the freedom of interpretation it gives the builder at times.  Most of the new cad plans of today have everything down to the exact detail, but these old plans leave a LOT of detail out, and leave it to the builder to figure it out later.  I like that challenge.  So my next step with the plans is to have another copy made, so I can cut them apart and start creating templates.

All on one sheet.

I took the plans out to my good friend Jay Burkart's shop this weekend, and we both had our own head scratching session looking at the different parts of the plane, Eut's modifications, and some of the interpretations we would need to make.  That's when Jay realized that this fuselage needs to be built via the crutch method.  I didn't recognize it because I'd never built one like that before.  So over to Jay's hobby shop supply we went for a couple of good matching pieces of medium balsa to use as the main crutch assemblies.  Now I have no excuse to get started.

Check out some of the former mods and this cool note about sheeting the sides.

Welcome to my blog

Initially, I'm going to use this blog to document the build of an old free flight airplane known as the Big Gull designed in 1938 by Winnie Davis, but in this case, I'm going to install RC equipment.  After that, who knows.  Maybe I'll keep it going with another plane, but one thing is certain, you will only see me build planes - I don't fly ARFs.

The original had a 153" span, but the scaled down 120" version is better aligned to what I'm looking for at the moment.  I wanted a plane that was going to be a challenge to build but still have a distinctive and attractive final outcome, and I think the Big Gull will provide that challenge.  SAM Hall of Famer Eut Tileston has supplied the plans for the 120" version of the Big Gull complete with improvements that he has incorporated into his Gulls over the years.  A big thank you to Eut for this contribution and for supplying the ONLY pictures of the Big Gull that I can find anywhere on the internet.  IF YOU HAVE BUILT ONE OF THESE BEAUTIFUL PLANES, PLEASE LET ME KNOW!

I haven't decided on all of the details, but the plane will be electric powered.  I'm in no rush to complete this plane, so sit back and enjoy the build.

Here are a few pics of the plane and Eut on the cover of SAM Speaks newsletter.  I can only hope to duplicate Eut's skills on this plane, but I'm going to give it a try!