8th Scale Aviation's, "CzechMate" Short-kit, Group build
#76

Thread Starter

With the installation of the shear webs "locking in" the washout, the washout tabs on the bottom of each rib can now be removed. I used a razor saw to cut away the tabs on the plywood ribs, and an Exacto knife to remove the tabs from the remaining balsa ribs. If you are going to be "off", it is better to err on the side of leaving too much material -- as this can still be sanded to the proper airfoil shape; than to cut into the airfoil, thereby altering its shape.

When using the razor saw, be sure to hold the end of the saw away from the trailing edge sheeting.
When using the razor saw, be sure to hold the end of the saw away from the trailing edge sheeting.
#77

Thread Starter

Here is the view of the bottom of the wing panel from the tip rib, after cutting away the tabs. Note that if they are not perfectly flush, I left just a little bit of the tab material behind.

The next step is to sand any excess tab material -- and that of the wing bolt reinforcement block -- off, so that the bottom of the wing is properly contoured to the airfoil shape.
The next step is to sand any excess tab material -- and that of the wing bolt reinforcement block -- off, so that the bottom of the wing is properly contoured to the airfoil shape.
#78

Thread Starter

A solid surface is also necessary for properly mounting and securing the aileron control horn. A filler block is needed at the point of installation of the control horn. Tim purchased a length of tapered aileron stock for this purpose.

Beings we are building 3 of these planes, simultaneously, I cut 6 lengths -- each approximately 2" -- on my table saw.
Beings we are building 3 of these planes, simultaneously, I cut 6 lengths -- each approximately 2" -- on my table saw.
#79

Thread Starter

Each 2" length of aileron stock was beveled slightly on each side to match the contour of the airfoil, when lined up with the tip of ribs and the beveled edge of the trailing edge sheeting. When happy with the fit, apply medium CA and glue to the sheeting as shown.
#80

Thread Starter

We repeated the process to this point to build the other wing panel for each of our wings. Obviously, the only major difference in the process is that the layout of the pieces is a mirror image of the first panel, so that there is a left and right matching pair of wing panels.

Here, I am installing the plywood ribs to the bottom spar, in reverse order, for my left wing panel.

Here are the two largely completed wing panels for my wing (foreground & right), and Tim's wing (background & left).
Here, I am installing the plywood ribs to the bottom spar, in reverse order, for my left wing panel.
Here are the two largely completed wing panels for my wing (foreground & right), and Tim's wing (background & left).
#81

Thread Starter

Although there is still more to be completed with the wing, before we could say the wing is "done", we decided to stop on the wings for the moment, and turn our attention to starting the fuselage.
Construction of the fuse begins with slicing through the retaining tabs to release the laser-cut parts from the remainder of each sheet.


Eric cuts his ply formers free from the cut-sheets.

I do the same; and many ofTim's are visible towards the back-left corner of the bench.
Construction of the fuse begins with slicing through the retaining tabs to release the laser-cut parts from the remainder of each sheet.
Eric cuts his ply formers free from the cut-sheets.
I do the same; and many ofTim's are visible towards the back-left corner of the bench.
#82

Thread Starter

Fuselage construction begins with the top half of the fuse.
Tim stacks all the top fuse formers into one pile, and snaps some pictures . . .

. . . while Eric and I continue to cut out all our parts.
Tim stacks all the top fuse formers into one pile, and snaps some pictures . . .
. . . while Eric and I continue to cut out all our parts.
#83

Thread Starter

There are laser-etched marks on the firewall. Using a ruler, these marks are used as a reference to draw "crosshairs" for the wing dowel retaining hole, and to mark the thrustline in order to center the engine mount.
#84

Thread Starter

The top fuse view of the plans were laid out on the workbench, as well. Unlike the rest of the fuse, the firewall does not have a top and bottom section -- it is one piece. Therefore, when building the top half of the fuse, the firewall will extend off the edge of the building surface, so the plans need to be aligned with the edge of the bench, accordingly. Carefully fold the plans at the back edge of the firewall; and suspend the portion in front of this line over the edge. Note that any misalignment could result in unintentionally introducing right or left thrust to the finished fuse.
#85

Thread Starter

The engine mount (the Dave Brown 60FS mount is pictured) is aligned with the thrustline and is tack-glued with four drops of medium CA, in preparation for drilling holes for the engine mount bolts and blind nuts.
#86

Thread Starter

Tim shows Eric how to use the GreatPlanes centerfinder for marking pilot holes in his firewall; and, the engine mount is then removed.
Pilot holes are marked on my firewall; and, the temporarily tacked engine mount can now be removed for drilling holes for the blind nuts.
Last edited by Iron Dog; 12-27-2015 at 06:49 PM.
#87

Thread Starter

Anyone following this thread, please give Tim and I some feedback. He would love feedback as to what you think of the design, thus far.
Additionally, I would appreciate feedback as to how my write-up of the build-log is working for you. It is a tough line to walk in order to give specific enough details regarding what we are doing, and the reasoning behind those choices to builders that are not very experienced, while hopefully not simultaneously "turning-off" more experienced builders by being too wordy.
What do you think, thus far?
Additionally, I would appreciate feedback as to how my write-up of the build-log is working for you. It is a tough line to walk in order to give specific enough details regarding what we are doing, and the reasoning behind those choices to builders that are not very experienced, while hopefully not simultaneously "turning-off" more experienced builders by being too wordy.
What do you think, thus far?
#96

Thread Starter

We drilled the holes in the firewall that were marked in the last step, and installed 6-32 blind nuts from the back side. After pressing them in by hand, I applied a couple drops of medium CA and set them in firmly by tapping them in with a hammer.

We then drilled the Cowl Mount's three pre-marked holes for 4-40 blind nuts and set them in the same manner as with the firewall.

Firewall and Cowl Mount with blind nuts installed.
We then drilled the Cowl Mount's three pre-marked holes for 4-40 blind nuts and set them in the same manner as with the firewall.
Firewall and Cowl Mount with blind nuts installed.
#97

Thread Starter

1/4 x 1/4" balsa stringers are pinned to the top view of the plans with T-pins. Then, the main (top) formers are placed per their locations on the plans, aligned with a builder's square, and glued to the stringers with thin CA. We started with the rear-most former, and worked our way forward.
Tim gets his stringers pinned down:
Eric mirrors our excitement that things are finally taking shape, while ensuring his formers are glued at right angles to the building surface:
Tim gets his stringers pinned down:
Eric mirrors our excitement that things are finally taking shape, while ensuring his formers are glued at right angles to the building surface:
Last edited by Iron Dog; 01-02-2016 at 07:47 PM.
#98

Thread Starter

Tim and I get our formers glued-in, as well. Tim marks a centerline on one of them (although I don't remember why).
Last edited by Iron Dog; 01-02-2016 at 08:23 PM.
#100

Thread Starter

I very carefully set my firewall in-place and check all angles. As stated before, any variance when installing this piece could unintentially introduce right or left thrust in the finished model if the plans are not set up properly to the edge of the work surface. Likewise, this former must absolutely be installed at a perfect right angle to avoid unintentially introducing up- or down-thrust.

Take your time with this one!

This is one of those steps when you wish you had 3 hands: one to hold the square, another to hold the former in-place, and a third to apply the glue. So Eric gives Tim an assist when Tim installs his firewall.
Gee, thanks Eric. Where were you when I needed help?
Take your time with this one!
This is one of those steps when you wish you had 3 hands: one to hold the square, another to hold the former in-place, and a third to apply the glue. So Eric gives Tim an assist when Tim installs his firewall.
Gee, thanks Eric. Where were you when I needed help?

Last edited by Iron Dog; 01-02-2016 at 08:27 PM.