1/3-Scale Cessna L-19 "Bird Dog" Kit by Peter Goldsmith Designs

[JimD]

With the fuselage right side up, we added the extension wires for the elevator servos.

Our preference is to custom make these extensions and we purchased our wire, connector sets, wire stripper and connector crimper tool from Hansen Hobbies. These are very high quality tools.

Twisted wire is also available from Servo City in Futaba and Hitec colors. Hansen Hobbies has twisted wire in JR/Spektrum colors.

We used rubber grommets to route extension wire forward through the bulkheads. McMaster Carr has a huge selection of sizes, the ones used here require a 7/16" diameter hole.

[Gordon McLean]

Jim - I really appreciate you providing the source for the additional materials used in your builds. Finding those items when you don't know who has them has always slowed me down...

[JimD]

Thanks Gordon...agreed that having a link to the source of items is a great help. Always appreciate it when others do this, so trying to return the favor!

[gunny11]

Nice build thread Jim, always following.
Keep up the great work!

[ARUP]

+1 from a lurker!

[JimD]

F6b through F12b can be added to the top side now. We used some scrap basswood sticks and clamps to hold the top formers in place while gluing. 1/8" balsa sheeting is then added in similar fashion to the bottom.





The 1/8" balsa sheeting on the side of the fuselage has to be cut to fit rather exactly, Not that hard to do, just measure twice and cut once!







Note how the sheeting covers only half of the thickness of the crutch (crutch is 1/4" thick).

The top side sheeting needs to runs from F12b forward to F4b.

Use scrap 1/8" balsa sheeting to make 1/2" wide cap strips to cover the sides of the fuselage formers.

[JimD]

We made a pattern (which is now included on the plans) to cut the top sheeting for the rear window. A sharp #11 X-acto blade and a razor saw makes short work of this cut.

[JimD]

The upper cabin is built from multiple parts that basically sit on top of the crutch. The front and back 3/8" dowel rods are very important in that they tie the upper cabin structure to the lower fuselage structure.

Locate F2b, F3b, F4b, F6 triangles, the inner and outer liteply window frames (8 pieces), the 3/8" dowel rod, and the top of cabin root ribs.

Note that F2b and F3b have tabs that fit into the notches of the top root ribs and provide the correct spacing between F2b and F3b.

Note that F2b, F3b, and F4b are NOT perpendicular to the crutch. They follow the slant of the lower F2, F3 and F4 formers.

Note that the bottom edge of F2b, F3b, and F4b are square and either this bottom edge or the crutch needs to be sanded to set the angle of the slant.

Note that the forward side window frames align with the front edge of F2b and align with the centerline of the edge of F3b.

Note that the elongated holes in F2b and F4b plus the elongated holes in F1b and F6b need to have edges angled to allow the dowel rods the sit at their proper angles.

We elected to use the edge of a large miling file to make an angled notch in the crutch at the placement of F2b, F3b, and F4b.

We also elected to glue a scrap piece of 1/4"x1/4" basswood to the inside edge of former F2 and extending upward to be attached to former F2b.

We started by test fitting F2b and the forward side window frames to the fuselage (no glue at this point) and marked where each part should attach.



Then we modified the elongated holes to accommodate the dowel rods. We used a round file to do this.







Here is the notch for F2b filed into the crutch and the 1/4"x1/4" splint glued to F2 and extending upward. Ink line marks forward edge placement of F2b.



F2b is glued into place using the 1/4"x1/4" basswood splints and the F6 triangles to help set the proper slant.



Here is the notch in the crutch for former F3b. The ink line marks the rear edge location of the side window frame (center of F3b edge).



Now the side window frames are added (while the glue for F2b is still wet). Align forward edges and rear at ink mark.







Allow the glue to cure before proceeding. These parts align the top cabin area and need to be carefully placed. Make sure you are satisfied with their placement now!

[JimD]

Next step is to add the 1/4"x1/2" basswood side window frame stiffener.

Note the notch between the window frame and formers.



Use F3b and the root ribs to set spacing, but do not glue them in place yet. Again, note the notch where the 1/4"x1/2" basswood stiffener will be inserted.



Cut a piece of 1/4"x1/2" basswood to length and sand an angle on the top of the window frame and the basswood stiffener to match bottom edge of the root rib.





Once satisfied with the fit, glue the basswood stiffener in place (but not F3b or the root ribs).

[JimD]

With F3b and the top root ribs clamped in place, test fit the inner window frames. These may need slight sanding for a proper fit. Ours needed slight sanding along the top forward edge.


Glue the inner frames in place. We used binder clips as clamps. these clips are readily available at office supply stores and come in assorted sizes. They are extremely useful and very inexpensive.




Now F3b and the top root ribs can be added and glued in place.






***Please note that we made an error with part R1c. We mistakenly glued it to the fuselage root ribs instead of the wing root ribs! So please disregard the R1c parts visible in this series of pictures.***

[JimD]

Next, the rear window frames are added. Glue along the bottom edge onto the crutch and the front edge along F3b.


Glue in the inner window frames.


Add F4b and 1/4"x1/2" basswood stiffener along the top like was done along top of front window frames. Note that window frames taper inward at the rear and glue to the edge of F4b. Tabs at top of F4b align with the aft end of the root ribs.


Dowel rods are fitted so there is no force or strain needed to insert them throught the holes.


We cut the lower ends at an angle so they fitted together and prevented them from sliding out of place while epoxy cured.





A piece of scrap 1/32" plywood was cut to fill the space between the root ribs and top of rear window frames.


Dash added, then stringers and sheeting.

[JimD]

Tow release mounting assembled, servo added, and a 4" Hangar 9 Titanium Pro-Link rod used for release pin. Cut the threads off one end and round that end.







Locate hatch parts, assemble frame.







Sand the top edges of H2 and H3 to follow the contour of the H1 ribs. 1/32" plywood sheeting is added to the framework to finish the hatch.

[JimD]

For now, we will move on to wing construction.

[JimD]

Wings

• Wings are sheeted with 1/32" plywood skins.
• Wing skins are in four pieces for both bottom and top. Eight pieces per wing.
• Wings are built over the lower wing skins which have laser etched lines for the placement of spar, ribs, leading edge and trailing edge.
• Wings are built in tow sections, the 24" inner panels and the 36" outer panels.
• Basswood 1/4"x1/2" spars are supplied as (4) 36" and (2) 48" lengths. The two 48" pieces are cut in half to make four
  24" spars.

We will start with the inner wing panels first. Locate the ribs and other parts for the inner wing panels. Cut the 48" basswood 1/4"x1/2" spar in half to make the top and bottom 24" spars.




Tape the bottom center panel front and back halves of the wing skins together.


Use the G10 and plywood flap hinge parts to align the Hinge Support Plates over the slots in the lower 1/32" wing skins. Do not glue the hinge parts in place, just use them to locate the support plates which are glued to the lower wing skin at this step.




Locate the 1/8"x1/4" basswood stick and cut a 24" long piece. The 1/64" Flap Fairing is glued to the edge of the basswood stick and needs to be securely attached so it will be exactly vertical along the side of the basswood. Holding these parts tightly together against the surface of your workbench (don't forget the wax paper) and glue with thin CA.


Clamp a straight edge to your workbench (steel ruler shown here) and hold the bottom 1/32" plywood bottom skin and the 1/8"x1/4" basswood stick with attached 1/64" Flap Fairing against it for correct alignment. Then use Thin CA to glue the parts together.


Use the ribs that fit over the hinge support plates to set the placement of the lower wing spar. Make sure that the rib fits over the rear 1/8"x1/4" basswood stick and that it folds over the 1/64" Flap Fairing as shown. Mark the main spar notch location on the 1/32" lower wing skin as a reference. This should match the laser etched lines, but if there is a slight variance, go by the mark that you just made for the spar location.

[JimD]

Note the use of the clamps to bend the Flap Fairing over so it does not "fight" the placement of the ribs while checking for the main lower spar placement. As noted before, Ribs wR2, wR4, and wR5 were used to check the position of the lower spar. Our parts lined up perfectly with the laser etched lines for the spar.









As ribs are glued to the lower sing skin, do not glue the curved rear edge of the rib to the 1/64" Flap Fairing.


Ribs wR2, wR4, and wR5 were the first to be glued in place. We used our bricks to hold them in place while the glue cured.



The remainder of the ribs were added along with the laser cut shear webs. Leading edge was clamped but not glued as this point.


Shear webs around the wing tube were gluedin with slow set epoxy and West System 404 filler.





Leading edge was glued on and the bottom edge of the plywood leading edge was lightly sanded to follow the contour of the ribs. Next step, a piece of stick wood was inserted under the 1/32" wing skin to hold it up tight against the leading edge while glue cured.

[JimD]

Next step is to add the strut mount blocks.

Since the struts are fractional width (4 pcs 1/4" wide) and the strut mounting blocks are metric width (4 pcs 6mm wide), a few early kits need to have an extra piece added to make up the necessary width (make piece from 3mm liteply scrap). End caps also need to be made from scrap 3mm liteply. These parts are laser cut and included in current kit.

Once strut mount blocks are glued together, they are added to the wing along with rib wR7.

[JimD]

Now that all of the ribs are in place, hold the 1/64" Flap Fairing tight against the curve of the ribs and glue with CA (critical that there is no gap between rib and plywood).



Next, add the 1/8"x1/4" basswood strip in the notches of the ribs along the trailing edge. Install the T-nut wing for the wing attachment bolt in part R1c and epoxy it to the inside of the root rib along with part Sh1b that supports the steel anti-rotation pin.