1923 B3 'Charlotte II' in 1:3 Scale

[ARUP]

Yeah, Len! I think I have the pics at a size my ISP can handle. No more 'activity wheel' spinning in the top left corner of the page after I post!
Spruce compression struts were let between the spars. 1/4" marine ply triangles cut and got epoxied to the compression struts. Drag and anti-drag cables get attached to these. Triangles of 1/16" marine ply added to spars. The angled extension spars attach to these.

[lenb]

Looks like "somebody" figured out how to post his pictures!!!
Nice layout and fantastic work...

[ARUP]

Yessir, Len! More time is spent preparing for activity and that doesn't even include my slow brain processing time figuring things out! The rib locations were marked onto the spars and the strut attach fittings bolted in place. The packing to hold the spars was pinned to the board. The ribs were slowly threaded onto the spars. This required lifting the spars off the packing multiple times then resetting root end alignment when the spars put back down. Not difficult but tedious. Ribs will get glued once the compression struts with their drag and anti-drag wires are installed. The ribs will get shimmed so the bottom of the rib contacts the spar. Music wire was threaded thru the TE 'eyes' for a quick check of alignment. Not bad alignment so far since the ribs aren't glued yet! Another pic is supposed to show how the noses of the ribs are pretty much in the same plane (pun intended ) to place the false spar and not induce twist. The extended portion of the wing that has the control surfaces gets built 'in the air' on spacer packing blocks. That'll really get tedious! I wonder how the 'real deal' was built?

[lenb]

Michael, so true the statement its 80% Preparation, 20% Installation .

[ARUP]

I forgot the diagonal braces on the elevators. They are the ones in pic above with aerodynamic counterbalances. I stuck a note on them so I won't forget! I got my train layout done! Looks like it, right? Actually, it was prudent to clear the bench to make spars. While bench was clear the 'twist' was measured at different stations along the wing span so the packing could be properly cut to hold the spars. The spars were fabricated. The fore spars are 1/4" square section spruce while the aft ones are 1/8" x 1/4" spruce. They have the same size shear webs of balsa. Mild sheet steel used to make strut attach fittings. These will bolt to 1/4" marine ply blocks properly placed as shear webs. One pic shows how the truss ribs 'thread' onto the spars.

[ARUP]

The micarta horns attach to bass wood 'rib' parts which are reinforced with 1/32" marine ply. I made a little jig to test fit the depth of the hinge so it can get epoxied into the rib. There are only two hinges per control surface so these have to be robust and accurate. When they were done they were test fitted to the control surfaces' spars. The elevators are the outermost control surfaces. Aluminum tubing was epoxied into a slot cut into the back of the spar. These tubes are spaced so that the control surfaces won't move or 'creep' laterally. These tubes also allow a 'piano hinge' pin to be removed allowing the control surfaces to be taken off the wing. All parts cut as 'doubles' at one time to ensure symmetry between left and right sides. The very last picture shows them all completed. The one in the lower right corner has its inside corners 'radiussed'. The other three need to be finished similarly. Once that is done then the wings get built!

[ARUP]

Thanks, Petr! Truss built ribs are pretty cool in appearance! The 'Hershey Bar' section ribs weigh 7 grams each. A similarly sized 1/8" medium density balsa rib without any cut outs or aluminum tube end weighs 6 grams. The truss ribs are stronger (or at least as strong?) in vertical loading but the balsa rib is stronger in lateral loading. Since the wing gets compression struts with drag and anti-drag bracing the ribs won't carry much in the way of loads so I'm happy with the weight of the truss ribs.

Elevator and aileron construction begins! The 'Charlotte II' had some kind of as yet to be discovered coupled drive mechanism for the control surfaces. One was driven by a regular pull-pull cable(?) but the other was driven by an internal gear drive with bevel gears(?) at the control surface hinge line. Vince Cockett and I discussed possibilities via e-mail. The easiest route is good ol' 'artistic license' again! I'm gonna make each one operate via pull-pull cables. The horns were drawn, cables' angles determined, et al. They were cut from micarta and finished sanded in preparation for painting. Music wire was heated cherry red, their ends hammered flat, hinge pin holes drilled then they got a general filing and clean up in preparation for the painting and install. The hinge pin will allow the control surfaces to be removable. The LE of the control surfaces will be built up in layers to allow placement of aluminum tube bushings to guide the hinge pin. I'll start cutting wood for the control surfaces tonight.

[stihac]

Good nose job on the ribs and very cool idea with the tubie thingies.

The ribs are piece of art. Most people's airplanes don't have as many parts as each of your ribs

Petr

[ARUP]

The 'Charlotte II' has a wire or cable TE. To anchor them at the rib TEs I came up with this solution. Aluminum tube segments were cut, slotted, then the 'slot flaps' were peened over a mandrel to make an 'eye' for the cable to pass. A slot depth of ~3.5mm found to be ideal. The 'mandrel' was a drill bit. Four of the tubes had to have 'angled' eyes to fit the ribs that transition from the Hershey bar portion of the wing to the extended ribs. These were fun to make! I made a few extras. I love whacking objects with a hammer! Where's Jeremy? A brass tube sized the same as the aluminum tubes was used to cut the rib TEs. The brass tube has 'teeth' cut into the end. Works great! The nose trimming jig was modified to become an 'aluminum tube spacing jig'. I'm of Irish heritage and love jigs! After all the aluminum tubes were epoxied in place 1/64" ply was glued to strengthen the rib ends. The ribs are done!!! Next... elevators and ailerons.

[ARUP]

Hey Asher! Yessir... BIG plug! Funny thing but I've set, topped, cut and hung 'backy' but never smoked, snuffed, dipped or chewed it except for an occasional cigar celebrating the birth of others' children. I love how tobacco smells in the barn!
Bob, thanks for checking in here! You hit the nail on the head... patience is what it takes! Everything else is a by-product, lol.
Len... thanks very much! Glad to contribute. Even if some folks aren't interested in these types maybe they will find them amusing or come away with a useful tidbit.

Off with their noses! The ribs got put on the jig in order to mark their noses for trimming. This will allow the false spar stay 'square' as referenced to the building board. Remember... the ribs gradually 'wash out' toward the tip so if they were all trimmed equally with respect to each other then the LE would have to be installed 'twisted' to compensate. I don't like 'forcing' materials into place. You can see how the penciled line aligned with the slot edge on saw. Easy-peasy!

[lenb]

Way to go Michael. Thanks for keeping the thread updated. Excellent build!!

[BobM]

Beautiful work Mike.........incredible attention to detail and amazing patience !

Looking forward to seeing it in person at some point this summer.

Bob

[Asher Carmichael]

Whoa thar yung fella, At's a mite big plug of "backy" you dun bit ofen fer yer sef. Shore tastin' gud tho, tain't it?
Incredible as usual, Mike.

[ARUP]

Here is a picture of the micarta patterns used to make the balsa LE and TE rib parts. It takes an hour or so to build a rib not including adding gussets. The second picture shows a stack of ribs for the constant chord portion of the wing and a rib on the 'LE trimming jig'. This is used to get the false LE nice and square when it gets added later. A root rib is 'belly to belly' to an outermost constant chord rib demonstrating the differences in the spar slot angles. Two of the extended ribs are shown plus a third one without gussets. The rest of the pictures are just close ups of the particulars. I have six more ribs to build. Whew!

[ARUP]

Petr- glad you are having quality time with daughter. Sailplanes can wait!
The Charlotte will get done when it's done. Sorry Stephane but this one gets maidened at the Horizon Hobby Aerotow along with the Franklin Eaglet. It's an informal 'tradition' Len and I have worked out. I can bring a small 1/6 scale Nimbus 4D to Wilbur Wright Birthplace Aerotow for you to maiden for me if I get it done. I only bought it back in 1996 or so! I have the retract and doors working properly, the canopy frame is painted with canopy installed and the spoilers work freely. They were a pain to get operating without hanging up. Just gotta finish radio install.
Dion, after you get your Cherokee done maybe you can put the Hols back on the board. If you build washout in the wing it won't fly as bad as some have experienced. I finished all the ribs for the straight portion of the Charlotte's wing. I started on the 'extended' ribs for the swept back portion of wing. They are a little more laborious. Has to do with swept spar and wing thickness transitions. I'll get pics soon. I have been cutting wood like a beaver!