ASTRO-HOG RC55
4. FUSELAGE SIDES

Cover the building board with wax paper. Pin printed balsa sheets No.7 and No.8 - the right and left fuselage sides - onto the board.

a.

With a modelling knife, cut loose from the rest of the printed sheet the small parts that are printed under the wing saddle area of each fuselage side. The part is marked A and B for the right fuselage side, X and Y for the left fuselage side. Save these parts to be used later.

b.

Cut to length and glue onto the fuselage sides all of the 1/4"sq. balsa corner stringers and vertical pieces. Be sure to leave a 1/8" gap in the corner stringers where formers F2 and F5 will go.

c.

Glue and pin balsa doublers FSD on the fuselage sides. Be very careful to achieve good alignment of FSD with the printed lines on the fuselage sides, as FSD will set the stabilizer at the correct incidence later.

d.

Glue lite-ply doublers LPD-1, LPD-2 and LPD-3 in place. Note the gaps between the doublers for formers F2 and F5. Use epoxy glue, not Sig-Bond or any other water base glue (the water can cause these parts to curl).




e.

Cut to length and glue in place the 1/2" balsa triangles that go along the front and bottom edges of doubler LPD-1.

f.

Trim completely around the outside edge of each fuselage side with a shap modeling knife, cutting away the excess printed sheet. Where structure has already been glued on, trim the excess away flush with the structure. At the front trim to the printed outline.

g.

Cross-match the fuselage sides by pinning them together and using a sanding block to true-up any rough edges. If the sides were built and cut accurately, not much sanding will be needed. Be careful when sanding in the wing saddle and stabilizer mount areas not to change the incidence angles.

h.

Finish cutting out the two small A-B and X-Y parts that were set aside in step 4a. Then glue them in place on the fuselage sides, pinning flat until dry. The corresponding letters on the sides will help align the parts correctly. Use a piece of waxed paper or plastic wrap underneath the glue seam to keep it from sticking to the board.




5. FIREWALL ASSEMBLY

NOTE: You need to have the engine and muffler that you will be using on hand when working on the firewall.

.

a. Epoxy the die-cut plywood firewall parts F1A and F1B together. Hold or clamp together until dry.

b.

Mark the vertical center-line and thrust line on the front of the firewall, using the F-1 cross-section drawing on the plan as a guide. Check the width of the engine that you intend to use and determine the spacing that will be required between the aluminum engine mounts. Now locate the mounts on the firewall accordingly. Mark the locations of the four mounting holes and drill them out with a 3/16" drill bit.

c.

Bolt the engine mounts loosely onto the firewall with the 5-32" mounting bolts and blind nuts provided. Double check to see that the mounts are lined up properly and then start tightening up the bolts. Keep tightening until the prongs of the blind nuts are started into the wood and holding. Now carefully remove the mounts and bolts from the firewall and tap the blind nuts the rest of the way into the wood with a hammer. Spread epoxy glue over the blind nuts to keep them firmly in place. Be careful not to get any glue in the threads of the blind nuts.

d.

Draw a line across the back of the firewall representing the bottom of die-cut balsa former F1C. Use the F-1 cross-section drawing on the plan as a guide. Now trim out the bottom of former F1C where necessary to clear the blind nuts. Then glue F1C in place.





e.

Hold (or tack glue) the firewall in position on one of the fuselage sides. Slide your engine back and forth on the mounts until the engine's thrust washer sticks out 1/4" to 1/2" ahead of the fuselage side. Mark the engine mounting holes on the aluminum mounts. Drill the holes with a #36 drill bit and tap for 6-32 mounting bolts. (See below)

TAPPING ALUMINUM ENGINE MOUNTS
Clamp the engine mount securely in a vise and center punch the motor mounting holes. Drill the holes with a sharp twist drill bit in a variable speed electric drill. If possible, use a drill press instead of a hand held drill. Lubricate the drill bit with machinist's cutting oil, special aluminum tapping fluid, or other light household oil such as Marvel or 3-in-1.
Run the drill at a moderate speed with moderate pressure. Let the bit cut its way through the aluminum at its own rate. Don't try to force it with excess pressure or high speed. Aluminum galls easily and may jam and break the bit if forced. If resistance builds up, back it out of the hole frequently and clean off the metal fragments. Relubricate the bit and hole with oil and continue drilling. Tapping the drilled holes is easy if the same precautions are taken. Lubricate the tap liberally with cutting oil. Use moderate constant pressure when turning the tap into the hole. If resistance builds up, back the tap back out frequently and clean the fragments out of the threads. Use plenty of oil and work slowly.

.

f. Position the nylon nose gear bearing on the front of the firewall and mark the mounting hole locations. Drill out the holes with a 9/64" bit and install 4-40 blind nuts and mounting bolts- in the same manner you did for the engine mounts in step 5c.

g.

Assemble the nylon steering arm and formed nose gear wire into the nose gear bearing on the firewall. Check it turns freely.

h.

A hole must be drilled through the firewall at this time for the flexible cabel pushrod that will operate the nose gear steering. First check these instructions further on and familiarise yourself with pushrod installation. Then fasten the supplied pushrod connector into the middle hole of the nylon steering arm. Turn the steering arm back against the firewall and mark the spot for the pushrod to exit and hit the connector. Drill with a 3/16" drill bit.

i.

Locate the best spot on the firewall for the throttle pushrod to exit and line up with your engine's carburetor control arm. Drill the hole with a 3/16" drill bit. Avoid placing the hole within 1/2" of the firewall edge. A 1/2" balsa cowl side doubler will occupy that space later.

j.

Cut a 7/8" dia. hole in the firewall for the tubes from the fuel tank to stick through. See section 14 "Tips On Tanks" for some recommendations for fuel tank selection. If you use a standard-style 12oz round or rectangular tank, as recommended, place the center of the hole 1/2" above the thrust line. If you elect to use a slant-style tank or a tank smaller than 12oz., you may want the hole a little higher. Plan your tank installation now!

A jig saw works best for cutting out the hole. Or, you can drill a series of smaller holes around the perimeter of the 7/8" hole, and then cut between the small holes with a keyhole saw blade (such as X-Acto #27).




6. JOINING THE FUSELAGE SIDES

a.


b.




c.

With a sanding block, bevel the rear ends of the fuselage sides as shown. Sand until the tail end of each fuselage side is 1/8" thick.

Glue the firewall in place on the left fuselage side. Use 5-minute epoxy and hold it square against a 90 deg. triangle until dry.
IMPORTANT NOTE: The bottom lip of former F1C should seat tightly against the top of the 1/4" sq. fuselage corner stringer.

Epoxy die-cut plywood formers F2 and F5 in place on the left fuselage side. Glue them on one at a time with 5 minute epoxy and use a 90 deg. triangle to hold them square until dry.

IMPORTANT NOTE: Both F2 and F5 have small die-cut slits on their sides which should line-up with the top of the 1/4" sq. fuselage corner stringer.



.

d. Epoxy the right fuselage side onto the formers and firewall. Use slow drying gue and lots of pins so that you have plenty of time for getting an accurate alignment of the fuselage sides to each other and to the formers before the glue dries. Make sure that the tail ends of the sides line up properly. Let dry.

e.

Glue the die-cut balsa formers F3, F4, and F5A in place. Space them out carefully between F2 and F5. The exact distances between the formares are shown on the side view plan.

f.

Cut to length and glue in place the 3/16" sa. balsa top stringers that go between formers F1C and F5A.

g.

Sand down the edges of the die-cut lite-ply cockpit floor until it fits between the two stringers that bridge across the sides of formers F3 and F4. Glue the floor in place.

h.

Align the fuselage on the top view plan, pinning the bottom of F2 and F5 to the building board. Pull the tail ends of the fuselage sides together and glue. Make sure that the joint is directly over the centerline on the plan. Let dry.




i.

Glue in die-cut plywood formers F6, F7, F8A, and F9A. Check side view plan for exact positioning in relation to the 1/4" sa. balsa uprights in the fuselage sides.

j.

Glue the die-cut plywood formers F8B and F9B. The bottom corners of these formers should be flush with the 1/4" sq. corner stringers.

k.

Cut to length and glue in place the 3/16" sq. bottom middle stringer that runs from the back of former F5 to the tail end of the fuselage.

l.

Cut four short pieces of 1/4"x1/2" balsa stick to use as cross braces behind former F5. Sand them to fit between the corner and middle stringers and then glue in place.




m.

Using a long straightedge and a modeling knife, cut a 3/32"x3"x36" balsa sheet diagonally from corner to corner.

Glue and pin the two tapered pieces onto the bottom of the fuselage. When dry, trim off the excess flush with the fuselage sides.

n.

Cut to length and glue in place the three 3/16" sq. balsa top stringers that run from former F5 back to former F9A.

.

7. FINISHING THE FUSELAGE

a.

Trial fit your fuel tank in the fuselage. Slip a 3/16"sq.x2-1/8" balsa stick (cut from scrap) between the top of the tank and the bottom of the fuselage top stringers. Slide the stick backward or forward until the tank sits level in relation to the top fuselage sides. Glue the stick to the stringers after you find the right spot.



b.

Glue die-cut plywood former F2A in place.

c.

Use a sanding block to bevel the ends of the 1/2"x4-3/16"x6" nose bottom block until it fits in place. Recess a small area on the front of the block to clear the nose gear blind nuts. Then glue the block in place. Don't get any glue in the threads of the blind nuts.

d.

Two pieces of 3/32"x4"x36" balsa are supplied for sheeting over the top of the fuselage formers. Use the paper patterns provided to cut the sheeting stock into 4 separate pieces - 2 for covering the front formers (F2 through F5A), and 2 for covering the rear formers (F5 through F9A). You'll find that the paper patterns are approximate only and slightly oversize to allow for minor variations between models. Slight trimming of the balsa sheets may be necessary to make them fit your airplane perfectly.

e.

Glue both the front sheeting pieces, along their bottom edges only, to the fuselage sides. Once these joints are dry, wet the outside surface of the sheets to make them easier to bend. Trial bend the left sheet down onto the formers to check the fit. Carefully retrim where necessary. Note that the top seam should overlap halfway onto the 3/16" sq. top stringer. When satisfied with the fit, apply Sig-Bond glue to the formers and stringers, and start pinning the left sheet securely in place. Finish trimming any rough edges after the sheet is pinned down.
Repeat the bending, gluing, and pinning process for the right side sheet, joining it to the left sheet at the top stringer.

f.

Attach the two rear 3/32" balsa sheeting pieces in the same manner you just did the front piece.

g.

Cut out the 1/2" balsa cowl side doublers from printed balsa sheet No.11. Glue the doublers in place.

h.

Sand the sides of the 5/8"x3-3/16"x4-1/2" balsa cowl bottom block until it fits between the cowl side doublers. Bevel the back end of the block to fit flush against the firewall. Shape the side view of the block to match the contour of the fuselage sides.



i.

Make an oval cutout at the back end of the block to clear the nose gear assembly. Hollow out the inside of the block enough to allow adequate movement of the steering arm. Glue the block in place.

j.

A 6" long piece of balsa triangle stock is supplied. Cut it in half and glue the two pieces in the front corners of the cowl. Cut and sand the excess off flush with the fuselage sides.

k.

Add the 3/4"x1"x3-1/4" balsa filler block that goes along the top of the firewall, between the cowl side doublers. Cut the block to the shape shown on the top view plan before gluing it in.

l.

Carve and sand all the wood in the top cowl area down flush with the fuse top sheeting

m.

Carve and sand the 1/2" balsa bottom block down flush with the bottom of formers F1 and F2.

.


n.

Carve and sand the remaining front corners of the nose to blend smoothly into the top and bottom contours.

o.

Shape the 1" balsa triangles and the inside of the top filler block to a pleasing contour. 80 grit sandpaper wrapped around a large diameter dowel is handy for this job.

p.

Carefully sand the remainder of the fuselage to final form. Round the bottom corners of the rear fuselage as shown in the cross-section drawings on the plan.




8. COCKPIT AND PLASTIC HEADREST

Trim the cockpit opening to finished size using the full size pattern provided with the plan as a template. Trim with a sharp knife and finish the edge with fine sandpaper.


Sand the outside of the headrest with 360 grit or finer sandpaper to remove the surface gloss of the plastic. Do not use courser sandpaper which will put deep scratches in the plastic. Deep scratches will often open up wider during painting and become prominent. Shape the bottom edges of the headrest with an 80 grit sanding block until it fits evenly onto the top of the fuselage.

If you are planning to paint your entire model, glue the headrest in place now and paint it later when you do the rest of the model. Glue it with Sig-Ment, Sig Epoxy, or cyanacrylate "super" glue.

If you are planning to use an iron-on pre-colored covering, paint the headrest separately and glue it in place after the fuselage has been covered. Peel off the iron-on covering where the headrest will sit so that it can be glued directly to the balsa.

CAUTION: Do not try to cover the ABS plastic headrest with Monokote or other iron-on types of covering material. The heat may melt and distort the plastic.


We recommend that the headrest be painted with Sig Supercoat Dope or Sig Skybrite paint for best results. Hobbypoxy, K&B Superpoxy, and Dulux (automotive) enamel have also been proven compatible with ABS plastic and can be used if desired. Do not use other paints, dopes, or finishes without testing to make certain it is compatible with the plastic.

.

Color paint can be put directly on the sanded headrest. Primer type coats are not needed if a good sanding job was done with fine sandpaper. The color paint can be brushed or sprayed onto the headrest. Try not to apply heavy, wet coats which may cause an "orange peel" effect. Put on light coats with adequate drying time between coats. Follow the paint manufacturer's instructions carefully.

9. MATING THE FUSELAGE TO THE WING

a.

Set the fuselage on the wing to check the fit. If necessary, lightly sand the wing saddle area of the fuselage to achieve a good fit with no large gaps.

b.

Carefully drill two 1/4" dia. holes through former F2 for the wing dowels. The exact locations for the holes are premarked on F2 by two small dimples.

c.

Cut the 1/4" dia.x6-1/2" long hardwood dowel supplied into three pieces - one 4" long elevator joiner, and two 1-1/4" long wing dowels.

d.

Grind or sand one end of both 1/4"x1-1/4" wing dowels to a sharp point - keep the point symmetrical and centered. Push the dowels into the holes in F2, leaving just the sharp points sticking out. (It may seem that the dowels go into the holes awfully hard at first, but they will loosen up after they've been pushed in and out a few times.)

e.

Carefully slide the wing into position, pushing the sharp dowel points into the wing leading edge.




f.

Remove the wing and drill two 1/4" dia. holes through the wing leading edge where indicated by the dowel punch marks.

g.

Remove the wing dowels from former F2. Put a piece of wax paper over the face of F2 and then reinsert the dowels through the paper back into F2. Push the dowels only 5/16" into F2 this time - leave most of the dowel length sticking out.


h.

Trial fit the wing in position, sliding it into the dowels. Check to see that the wing still fits the fuselage. If not, slowly enlarge the holes in the wing leading edge until it fits properly. When staisfied with the fit, coat the inside of the holes in the wing with epoxy glue. Put the wing back in place and hold securely in position until the glue dries. When dry, carefully remove the wing, pulling the dowels out of F2. Fill any small gaps around the dowels at the wing leading edge with another application of glue.

i.

The 3/4"x3/4"x1-1/2" hardwood wing bolt blocks must be shaped to fit properly in the fuselage. Bevel one end of each block by drawing a line on it matching this pattern, and then sanding to the line. This beveled end fits snugly against former F5 when the side of the block is lined up with the wing saddle.



Bevel the side of each block next. Draw a line on the block matching this pattern and sand to the line. This beveled side should fit snugly against the fuselage side when the end of the block matches the dihedral angle (indicated by the bottom seam of former F5). Be sure to make a right and left block.

.

After shaping epoxy the blocks in place

j.

Reinforce the wing bolt blocks with pieces of 3/4" balsa triangular stock, cut from the 6" long piece provided.

k.

Tape or pin the wing in correct alignment on the fuselage. Determine the correct spots on the bottom of the wing and drill through and hit the hardwood wing bolt blocks in the desired locations for the nylon bolts. Drill through the wing and the hardwood blocks at the same time with a No.7 drill. (Remember to keep the drill perpendicular to the bottom surface of the wing so the heads of the nylon bolts will seat flush against the wing.

l.

Take the wing off and tap the hardwood blocks with a 1/4-20 tap. Redrill the holes to 1/4" dia. to pass the nylon bolts.




m.

Two pieces of 3/4"x2-1/2"x2" balsa are provided for making a fairing behind former F2 on the bottom of the wing. Bolt the wing in place on the fuselage and shape each block to fit down into half of the cavity.

n.

Carve the blocks roughly to shape so that the contour of the fuselage is carried onto the wing.

o.

Glue the blocks onto the wing, not to F2. When dry, finish sanding them to shape. Fill any remaining gaps with model putty or wood filler(*) to complete the fairing.




10. STABILIZER AND ELEVATORS

Pin the stabilizer/elevator plan to the building board and cover it with wax paper.

a.

Cut to length and pin on the plan the 5/16" sq. balsa stabilizer trailing edge.


b.

Glue the die-cut 1/8" lite-ply doubler against the front of the trailing edge.

c.

Cut the S-2 parts from the printed balsa sheet No.10. Glue and pin them in place against the trailing edge.

d.

Cut to length and pin in place the 5/16" sq. spruce leading edges. Add a short doubler, also cut from the 5/16" sq. spruce stock, behind the leading edge center joint.

e.

Cut to length and glue in all the 3/16"x5/16" balsa strip ribs.

.

f. Cut two pieces of 3/16"x3/8" balsa for the top spars. Glue in place on top of the strip ribs and S-2 pieces. Let the entire stab assembly dry completely before proceeding!

g.

When dry, unpin the stabilizer from the board and glue in the two die-cut balsa S1 ribs. Make sure the ribs are centered on the leading and trailing edges so that the 3/32" balsa sheeting to be added later will be flush.

h.

Cut to length and glue two 3/16"x3/8" balsa spars onto the bottom of the stabilizer.

i.

Add the 3/32" sheet balsa fill-in to the top and bottom of the stabilizer center-sections. Notice that at the front, the fill-in sheets butt up against the back of the 5/16" leading edge doubler, they don't overlap it.

j.

When dry, sand the point off the front of the stabilizer. Make the flat spot as wide as shown on the plan.

k.

Taper the tip ends of the top and bottom spars down to the edge of the S-2 pieces.

l.

Mark a center-line all the way around the outside of the stabilizer. Using the line as a guide, carve and sand the stabilizer leading edge, trailing edge, and tips round.




m.

Sand the 3/32" center-section sheeting smooth. You will note a slight mismatch where the sheeting meets the leading and trailing edges. Fill in these small voids with wood filler or model putty(*). DO NOT try to sand the voids completely out instead of filling them in, or you may sand down the leading and trailing edges too much and weaken them.

n.

Two 13-1/2" long pieces of 1/4"x3" balsa tapered stock are provided for making the elevators. Cut one of the elevator patterns from the plan and trace the outline onto both pieces of tapered stock. Cut the elevators to shape. IMPORTANT: Notice that one side of the tapered stock feels slightly rough while the other side is presanded smooth - plan your cutting of the left and right elevators so that the smooth side is used as the bottom for both.

o.

Join the elevators together by gluing them to the 1/4"x4" hardwood dowel joiner. Pin straight and flat on the building board until dry.




p.

Block sand the rough side of the elevators flat and smooth. Sand carefully so that the 1/4" leading adge thickness is maintained.

OPTIONAL: When block sanding (to the right), steepen the taper a little bit near the tip of the elevator to make the trailing edge a constant thickness along the back. This sounds tricky, but actually won't take more than a few passes of the 80 grit sanding block.

q.

Sand all the edges of the elevator assembly round. Hold the elevators up to the stabilizer trailing edge to blend the shape of the tips together.

.

COVERING NOTE: Whether you intend to use a dope-on covering material or an iron-on pre-colored covering, it is best to cover the stabilizer and elevators at this time, before preceeding to the next step.

r.

Hinge the elevators to the stabilizer by installing 6 molded plastic hinges where shown on the plan. Use the same basic procedure you did for installing the aileron hinges.

11. FIN AND RUDDER

a.

Cut out the fin parts FN-1, FN-2, and FN-3 from the printed balsa sheet No.9. Glue the parts together using the connecting key letters (A,B,C) for alignment. Pin down flat on the building board until dry.



b.

Sand both sides of the fin smooth with a sanding block, removing the printed ink lines in the process.

c.

Sand the leading, trailing, and top edges of the fin round. Do not round the bottom of the fin where it will be glued onto the fuselage and stabilizer.

d.

A piece of 1/4"x3"x10-1/2" balsa tapered stock is provided for making the rudder. Cut the tapered stock to match the rudder pattern on the plan. Finish shaping the rudder by sanding all the edges round.

COVERING NOTE: If you intend to use or an iron-on pre-colored covering material, it is best to cover the fin and rudder at this time, before preceeding to the next step.

e.

Hinge the rudder to the fin by inserting 4 molded plastic hinges where shown on the plan. Use the same basic procedure you did for installing the aileron hinges.


12. ATTACHING THE TAIL SURFACES

a.

Bolt the wing on the fuselage and pin (don't glue) the stabilizer/elevator assembly in place. Carefully check the alignment of the stabilizer with the wing from the top view. Measure from the back of the wing to the stabilizer hinge line on both sides.

Also check the alignment of the stabilizer with the wing from the front view.

When properly aligned, use a pencil to draw the exact location of the fuselage on the bottom of the stabilizer center section. Unpin the stabilizer and remove it from the fuselage.

b.

If you've precovered the stabilizer as recommended, remove the covering material from the marked area to insure a good wood-to-wood glue joint with the fuselage. Apply slow drying epoxy glue and pin the stabilizer back in position. Recheck the alignment again and adjust the stabilizer position if necessary. Pin securely and let dry!


c.

Epoxy the hinged fin/rudder assembly in place, installing the bottom hinge into the rear of the fuselage at the same time. Align carefully, making sure the fin is perpendicular to the stabilizer. Let dry!

d.

Cut the tail fairing blocks from the printed balsa sheet No.11. Shape the blocks to fit each side of the fin. Glue in place.