Click Here to return to the Index

 Sailplane Construction Project Session #146

Comet Sailplane Project
Early on in this project, the trim scheme I selected for the fuselage was a simple ring around the front of the cowl transitioning into a tapered stripe down the side of the fuselage. Conceptually, what I had in mind was something like is shown in the sketch below, which is straight forward except for the trim up on the cowl.
Now that the time has come to put on the trim, I had to get serious about the design of the trim pattern up on the cowl. Below are three sketches I considered before finally selecting No. 3. I have also made the decision to paint the trim on the Sailplane and to use Tamiya Acrylic.
To begin with, the four cowl alignment pins were inserted in the firewall and the cowl was pressed onto the firewall and taped in position. In order to lay out and mask off the trim pattern on the side of the fuselage, a straight reference line was needed. In the picture below, you can see that a piece of black thread was taped down on top of the center side stringer at the rear of the fuselage and stretched tight along the stringer forward where it was taped to the forward edge of the cowl.
Pieces of tape was put on top of the black thread and across the fuselage/cowl intersection on either side of the fuselage as shown below.
The tape and the thread were carefully cut at the joint and the cowl then removed from the fuselage as shown below. Notice that the tension of the black thread was preserved on both the cowl and the fuselage.
Using 1/4" "low tack" red vinyl masking tape, a ring was taped off around the forward end of the cowl as shown below. In addition, two pieces of the red masking tape were placed on either side of the black thread.  
Using 1/8" wide Pactra masking tape, the trim pattern was laid out free hand on the left starting and ending up along the outside edges of the red masking tape as shown below. The trim pattern was laid out in such a way that the width of the trim around the forward end of the cowl was 1" and that the tapering stripe starts out 1/2" wide as shown below. 
Now the free hand trim pattern had to be duplicated on the right side of the cowl. So a piece of bond paper was laid over the taped pattern on the left side and a No. 2 pencil was used to shade in the pattern curve as shown below. 
A paper pattern was cut out, taped to the right side, and the 1/8" Pactra masking tape was laid down along the edge of the paper pattern as shown below.
Even though the upper portion of the pattern was further complicated by the cowl's exhaust cut out, this technique worked out fine as shown below..
The red masking tape and black thread was then removed, leaving the cowl's trim pattern on the left side masked off for painting as shown below. Of course additional tape will be added to the outside of the Pactra tape to prevent getting paint on the outside.
This shows the cowl's trim pattern on the right side masked off for painting.
With the cowl taped back onto the front of the fuselage and using the black thread tight string as a center reference, 1/4" Pactra masking tape was used to mask off the long tapering stripe down the side of the fuselage. Notice the black thread tight string running in the center of the strip.
This is a view of the total trim pattern from the left side of the fuselage.
Tomorrow, additional masking tape will be added outside the trim pattern. The inside of the mask will be clear doped to seal the edges. Finally when the clear dope is fully dry, semi gloss black Tamiya Acrylic will be carefully brushed on to the mask. One thing I am not too clear on is how long to let the black Acrylic dry before starting to remove the masking tape. If any of you have experience in this area, please make a recommendation?........................Tandy  

Click Here to go to the next page (147)....