Halberstadt Cl.IV

[Paperwarrior]

Amazing work on those machineguns. Great techniques.

Jeff

[DrLaser]

Thanks again guys. Now for the struts.

To build up of the struts, I cut out the wings struts leaving extra on the ends. I'll need that extra for assembly. Using the reverse side color piece (with no lines that I have to line up), I simply glue the struts down. It will be a simple matter to cut them out, edge sand a little, and color.


I'll need to use my needle tool to poke holes in the struts right at the base (where the wing surface will be) for the rigging wire to threat through. I'll leave a short piece of rigging in the hole during assembly - acts as a stop and prevents the hole from gluing shut.


I now have to make the slots in the wing for the struts. My assembly procedure is to make the struts with a tab that gets inserted into the wing - just like a mortise and tenon woodworking joint. That joint is very strong, and provides a lot of glue surface. I already cut a slot before I built the wing. Now I work open the slot with a disecting needle and Xacto blade to create a tenon the right size for the strut. It's not as difficult as it may seem - working with magnification.
I handle the struts with tweezers during this entire process being very carefull not to bend or smash the strut or its end. Two pieces of glued cardstock is not very strong, so I'm real careful. I'll strengthen the struts but I can't do that until after the top wing is glued in place. For now, I dry fit the struts to be sure all is goodness.


When I'm satisfied, I'll darken the strut tabs (just in case) and glue them in place, my left side ones first (as I'm right-handed). I made an alignment guide for the strut angle using a 3 view drawing. After I plug in the strut there is plenty of time to place the strut into perfect alignment in two dimensions. The struts slant forward, are not parallel to one another, and perpendicular to the wing in a front view.


Here is how it looks with the wing struts ready to accept the top wing.


Next time I'll attach the top wing.

[Don Boose]

I'm catching up with the last few entries, John. Excellent narrative description and a cornucopia of valuable techniques to add to the Paper Modeler's Vade Mecum.

Don

[DrLaser]

Thanks Don. I'm am honored to be added to your reference work.

Adding the top wing is fairly straightforward. First I set things up and see if the struts line up with the slots. Close enough, got the angles right.


Now I trim the strut tabs. The rear strut tab is rather short because the wing's chord is rather thin. I insert some rigging tippet through the strut holes, then carefully insert the strut tabs into the wing slots, dry fitting the wing in place using tweezers and check the fit. Looks good to me!


Now pull apart one wing and glue the struts in place - one at a time, don't need the glue setting before you set things in place. Then the other wing. Now I have a biplane!


Next I need to make the cabane struts and glue them in place.

[Don Boose]

Another excellent set of images and instructions. The Halberstadt in those markings was a good-looking airplane and the paper model, as you have built it, is a real beauty.

Don

[Paperwarrior]

Great tips, John. This is really coming together. I look forward to applying these techniques on my next bi-plane. I've been copy and pasting this thread into a Word document to archive it.

Jeff

[DrLaser]

Now I'll finish the struts.

The cabane struts consist of a V strut and a single strut. I cut out the inside of the V shape first, so the remaining paper can support the part and prevent it from any damage through stress or warping or whatever. When I cut the inside corner of the V, I like to make a preliminary relief cut in the paper so I don't stress the part when I cut it out.


I cut out the struts and glue them to the back side color piece. I cut out the inside of the V, then color it before I cut out the outsides. This way, the remaining uncut paper helps support the part while I color the inside.


I finish cutting the part, and color it. Notice I left some tabs on each strut end. One tab will fit into the wing slot, and the others are for just in case.


I trim the tab to fit the V strut into the wing slot, and dry fit it in place. Notice I cut a block of blue foam and used it to immobilize the top wing at just where I want it while I attach the struts.


Now I can adjust the lengths of the struts to fit exactly onto the fuselage. I usually use simple butt joints to attach the struts to the fuselage. I trim little by little - pretty hard to add back some length if you trim it too much. Once all is good, I glue the V strut in place: first into the wing, then onto the fuselage. Then I do all this for the single strut.


After I repeat for the other side, I'm done!


Next I'll get to the real fun part - the rigging!

[DrLaser]

Before I continue, I must say that at this point in the construction, the wings are incredible rigid and locked in place. That is because of the large slant angle the cabane struts possess. The Germans certainly knew how to design a biplane.

But I am still worried about the strength of those long wing struts. I generally like to improve the stiffness by laying a thin coat of Super Glue (CA) on the front and rear sides of the strut - that is where I'll gain the side-to-side strength I'm looking for. I don't over do it and I am very careful not to get too near the ends of the strut or on the wing. After the CA treatment, the struts are much stiffer.

Now I refresh my memory on the rigging plan. This photo I took of this Halberstadt at the Udvar-Hazy Center shows all the key rigging clearly.


Now I remove the short lengths of rigging wire in the struts during their assembly, and start with a front wire going from the inner top to the lower bottom. Then cross it over the struts and feed it through to the lower rear.


Now I need to poke a hole in the fuselage at where the lower wing spar would be, and feed the rigging into the fuselage. I feed it all in, but it never emerges - getting stuck inside. I figured this would happen because the lower wing support blocks the way out. This is where I use an extraction tool I made for just this occasion. I reach in and easily pull the rigging out.


So here is the rigging of just one wire as it feed to and fro.


Now repeat for the rear rigging wire, feeding it through the strut, across and back to the front fuselage - entering the fuselage at the front of the lower wing attachment point, and pulling through the fuselage.


Now rig the cabane wires into the fuselage and through.


Next I'll repeat for the other side.

[DrLaser]

Okay, the other side is done. Now I have the landing gear rigging wires still remaining to go somewhere. Soooo, I need to build the landing struts next. The struts are built up just like the wing struts. I glue them with butt joints using a jig to get the angle right.


The cross strut attaches to the bottom of the V struts.


Before I glued the struts to the fuselage, I punch two holes in the end of the V strut to accept the rigging. The rigging is standard cross bracing. This rigging terminates into the fuselage at the front attachment point. This picture shows how the rigging is threaded.


Now all the rigging wires have been threaded correctly into the fuselage. I'm now ready to tension and glue off all the rigging.

[jagolden01]

Beautiful work on this rigging, John. And the tutorial is invaluable.