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By John Goschke
March 2002
The Basics
In addition to the usual knives, files, sandpaper and sanding sticks, adhesives…dividers, it is helpful to have a steel ruler with a division to 1/64", a small 90 degree drafting triangle, a cutting mat or sheet of glass marked with 1/8" - 1/16" grid, a good plan view drawing of the subject, and GOOD LIGHT.
1. Test fit - Constantly!
2. Tape or tack together major components of the model, including interior floors and bulkheads.
3. Fix problems by trimming and shimming - gradually, and on the least conspicuous areas of the part.
4. Achieve a tighter fit on the outside edge of parts by beveling mating surfaces to the inside.
5. Check fuselage and wing halves, etc. for true straightness and flatness; some parts will align during assembly - those that don't, twist or bend (score or cut and glue first if necessary) to correct.
This is the relationship of the components of the finished model to each other and the relationship of the model to the ground plane. Along with well-executed seam work and painting, alignment is an important factor in creating a successful model. The amount of time and effort needed to achieve proper alignment is, in a large part, determined by the quality of the kit. Many older kits and most limited run resin and Vacuform kits require careful planning, test-fitting and reengineering to achieve proper alignment.
a. Check the "out-of-the-box" alignment by taping or tacking the model together. If possible, stand the model on its landing gear struts to check for level with ground plane.
b. During assembly, on most aircraft use the fuselage seam and the vertical tail as a reference point for the alignment of other components.
c. On aircraft with conventional tail arrangements and a non-dihedral tailplane, set the horizontal stabilizer at 90 degrees to the seam in the vertical stabilizer/rudder edge. Check with a drafting triangle.
d. Set the opposite stabilizer to align with the first one by sighting the trailing edges with a straight edge; check against the rudder edge with a triangle. Check the alignment of the leading edges by sighting it from the front of the model.
e. On an aircraft with a dihedral tail, use dividers to measure the distance from the vertical stabilizer tip to the horizontal stabilizer tip. Then, set the other side to match. An additional method is to use drawings to make a dihedral angle pattern to set the proper angle.
f. Refer to drawings to set the dihedral angle of the wings by eye. Another method is to use the drawing to make a pattern for setting the angle.
g. When attaching the wings, carefully refine the fit before cementing it together.
h. To cement a one-piece wing assembly together, tack it in place on one side. Use slow-setting cement that will permit adjustments to be made before setting.
i. Check the alignment by sighting the wing and the horizontal stabilizer relationship.
- From the front, turn the model nose up or down until the horizontal stabilizer's tip appears to touch the top of the wing on one side. Sight the other wing to see if it matches. Adjust one side up or down as necessary.
- From the back, turn the model nose up or down until the horizontal stabilizer's tip appears to intersect the trailing edge of the wing on one side. Sight the other wing to see if it matches. Adjust the un-cemented side up or down slightly if necessary.
j. With the alignment adjusted, use capillary action to flow liquid cement into the wing joint on each side.
k. On aircraft with separate left and right wings, attach one wing to the proper alignment and dihedral. Attach and adjust the other wing to match the first, checking the alignment as in Step I found above.
l. When attaching the landing gear, install the struts first. A tight, dry fit will help make the following steps easier…
m. Cement one main gear strut at the proper angle.
n. Attach the other side and refine the angle to match.
o. Using a cutting mat or sheet of glass marked with 1/8" - 1/16" grid, set the model up on its gear, placing the fuselage centerline on one line of the grid. Make sure that the struts touch the grid at exactly the opposite points in relation to the centerline. (Adjust by carefully bending if necessary). From the back, use the 90-degree triangle to check for level by measuring each wing and horizontal stabilizer to make sure they are the same height off the ground plane. (Adjust by shortening or lengthening the top of the dry-fitter strut - remember that a small change at the strut makes a big difference at the wing tip).
p. Reshaping the axle hole on one landing wheel can also be used to make level adjustments.
q. Use the grid/ground plane to also check the alignment and level of the other features, such as multi-engines, wing guns, ordinance and drop and tip tanks.
r. Some aircraft, such as biplanes, floatplanes and those with twin fuselages (P-38, C-119), may require a jig mounted on the grid to assist building in the alignment.
This is closely related to, affects, and is affected by alignment. This describes the exactly opposite placement of critical features such as wing, horizontal stabilizer and landing gear attachments, control surface breaks and those less critical features, such as exhaust stacks, windows, guns and panel lines. Here, again we're frequently dealing with problems inherent with the kit. The modeler must decide how far they want to go in correcting these problems.
a. During the test fitting/tacking together step, check the wing and horizontal stabilizer attachment points for symmetry. (Many otherwise excellent models frequently have one stabilizer attachment higher, or slightly in front of its mate). Fix as desired by adjusting and compensating, reshaping, removing and reattaching or rebuilding.
b. Check also the control surface breaks and panel lines that cross seams and trailing and leading edges. Fill and rescribe as necessary.
c. On older kits, don’t assume that wings or other features are the same shape. Check this by placing one on top of the other to see if they match.
d. Resin kits frequently have wings that are of a different thickness.
e. When rescribing panels and attaching parts that have a mate on the opposite side of the plane, use dividers to transfer the measurement of the locations from one side to the other.
Maybe the first thing people, particularly contest judges will notice about your model, after the paint finish, is a bad seam - (really Great seams are invisible). Again, we're at the mercy of the kit manufacturer. But time spent here will do more for a model than any photoetch detail set or resin cockpit…
a. Avoid the use of fillers by fixing gaps before assembly. Add slightly oversize plastic shims to the edge of parts with cyanoacylate cement. Then, trim as necessary. Test fit frequently.
b. Use cyano gel to cement fuselage, wing and other required halves together, allowing a little excess to squeeze out of the joint. Allow drying. File the excess cement almost flush with the surface. (Polish if desired).
c. When filling and sanding, follow surface contours and avoid flat spots. Do a little bit, wipe the area clean, check it and repeat the process.
d. Wings and tail joints can be filled using liquid cyano, flowed into the joint by "capillary action." Use repeated applications of small amounts, as necessary.
e. Acquire and use a wide variety of files and be prepared to improvise. Sanding blocks and sticks will enable you to get in to the various inside angles and curves created by wing and tail joints.
f. Rescribe panel lines and control surface breaks across seams as necessary. Sand smooth. Clean sanding dust from panel lines with a stiff brush, or sharp tool of material slightly softer than the kit's plastic.
g. After cleaning the model to ensure proper adhesion, airbrush with a medium grey primer or silver metallic paint to reveal any small imperfections. Repair as necessary with small applications of cyano or spot putty. Wet sand smooth as specified above.
h. Don’t use cyano to attach clear parts. It will fog them. Cement in place with watch crystal cement for a strong, flexible bond. Then blend in with Elmer’s White or Carpenters or Micro Kristal Kleer.
The most important elements of an accurate-appearing model of a particular aircraft are:
a. The fuselage and vertical tail profile.
b. The Wing dihedral angle.
c. The "Posture" and landing gear details.
d. The canopy, windscreen and window shape, in addition to their placement and proportions.
Sometimes, a subtle change is all that's necessary. Decide how far you want to go.
1. Basic accuracy modifications, such as thinning flight surface trailing edges and drilling out exhaust stacks and gun barrels will increase the realism and visual impact of any model.
2. Using drawings and photos as a reference guide, determine what profile changes are needed to enhance the accuracy of the model's shape. Concentrate on the fuselage, engine cowlings/nacelles, and vertical tail. In most cases, inaccuracies in wing and horizontal tail outlines are much less obvious.
3. Using drawings and photos as a reference, carefully modify the fit of the landing gear if necessary, to give the model the right posture. Note in particular how much of the wheel is covered by the landing gear cover - (is it half, more or less?) Also, what is the characteristic angle of the struts from the front and side?
4. Most kits need thinner landing gear doors that fit more closely to the strut and wheels. Again, use reference material to achieve the proper relationships and angles.
5. Bad canopies spoil many otherwise good kits. Recontour with files, then wet sand, polish and coat with Future Floor "wax" to restore the shine. (Also, use this technique to remove inaccurate bracing and framework). Many accurate Vacuform canopies are available from Squadron and Falcon. Otherwise, use modified kit canopy as a master to vac your own.