Tamjets A4 Skyhawk User guide

Tamjets
A4 Skyhawk
Assembly and Flight Set-up Manual
Specifications:
Wing Span………………….48”
Weight (Dry)………..18.5 – 21 lbs
Fuel Capacity………………70 oz.
Overall Length……………..70"
Radio……………………….Min. of 8 channels required
Turbine Power ..……………13 to 17 lbs thrust turbine

Alignment: Wing Incidence………………. 0 degr. To Thrust line
Wing Dihedral..……………….0 degr. (at trailing edge)
Horizontal Stab. Incidence…….0 degr. To Thrust line
Thrust-line ..……………..…….0 degr.
Radio Requirements:
8 Ch. Minimum Computer Radio
Ail, Elev, Flaps & Rudder servos………JR-3421 or equal.
Steering ………………….… 60-70 in./oz. Hi Torque Std.
Retract servo…...…..... Mini. 50 in./oz. OR Jetronic valve.
Center of Gravity: Located on the CENTERLINE of the FORWARD WING TUBE.
C.G. with gear down and UAT full.
Control Throws: Elevator…………… 3/4” Up and Down W/ 25% EXPO.
Ailerons……. …… 7/16” Up and Down W/ 25% EXPO.
Rudder.………………………………..1” Right and Left.
Flaps……………………………….1/2 flaps 1” Take off.
Flaps… Landing 1-7/8” mix 1/8” up Elevator and mix crow.
Crow Setup…Flap – 1-7/8” for Landing mixed with 3/16” UP
Aileron.
You will find the assembly to be straight forward provided that you follow these instruction
in the sequence as outlined. An assembly jig is now available from TAMJETS to aid in the
alignment of the wings to the fuselage ensuring proper wing and supporting bulkhead
alignment.
Adhesives:
The following information is provided as a guide for glues and structure fabrication.
CA+ or 15 Min Epoxy Tacking parts into place.
Aeropoxy (Hysol) Final gluing of all bulkheads etc. to Fiberglass.
Fiberglass preparation for gluing:
Thoroughly sand all areas with 60 grit paper where bulkheads and etc. will be mated to
the fiberglass. Wipe down this area with acetone or lacquer thinner.
Painting:
It is recommended that the entire airframe be completed and equipment installed
BEFORE painting is performed. Light sanding with a Medium 3M pad is needed before
application of primer.

Hinges pivot point
Servo control arm and linkage hook up

BEGIN CONSTRUCTION:
FUSELAGE:
1. Locate all plywood components that will be fitting into the Nose cone. Trial
fit all parts together and LIGHTLY sanding any part that may cause the
fiberglass to “BULDGE” as we do not want this tight a fit as we must allow
for the glue joint as well. The TRAY is to remain REMOVABLE !
2. When satisfied with all fits, sand the fiberglass in the areas of the glue joints
and proceed to tact glue bulkheads into place and finish with a bead of Hysol
9462. Allow to cure overnight at room temperature

3. Trial fit all bulkheads inside of the fuselage and sand (if needed) to obtain
proper fit-up to the fuselage and sand the fiberglass in these bulkhead areas as
well. DO NOT GLUE AT THIS TIME.
4. Locate the forward fuselage bulkhead and drill (3) 3mm holes (# 31 Drill) as
shown. Maintain ¼” edge distance to holes.
5. Trial fit this bulkhead into the fuselage as shown. When satisfied with fit, tack
into place with CA+ then finish with Aeropoxy.

5. Trial fit the nose cone to the fuselage and transfer the location of the 3) 3mm
holes onto the bulkhead in the nose cone. Remove the nose cone and drill
clearance holes to install 3) “T” nuts on the forward side of the Nose cone
bulkhead. Install the “T” nuts with CA+.

6. Assemble the TAMJETS A4 assembly jig using CA+. With the Fuselage
positioned in the jig, slide the Wings into the fuselage. Insure that the wings are
tight against the fuselage sides. When properly fitted to the fuse, the ROOT of
the wings should be resting on the JIG SADDLES. Support the wings at the tips
using the jig supports, check the Dihedral as it shall be 0 degrees from wing tip
to wing tip as measured at the trailing edge AND 0 degrees INCIDENCE
measured at the wing root. When satisfied, proceed to step 7.
Use Velcro straps to secure Fuselage to Jig.

NOTE: Check to see that the vertical fin centerline is 90 Degrees to the work
surface using a square. IF it is not, shim UNDER the fuselage jig to accomplish
this before performing step 7. Maintain this alignment when installing wings and
horizontal stabilizers later !!!
7. Slide the wing tube clamps onto each of the 4 wing tubes.
8. Install Wing mounting bulkheads. Sand these bulkheads (if needed) to provide
1/32” clearance with fuselage)

9. With the bulkheads positioned against the clamps, double check to insure that
the wings are properly supported in the jigs and aligned per step 6, tack the
clamps to the bulkheads with CA+ and allow to cure. DO NOT GLUE THE
BULKHEADS to the FUSELAGE at this time.
10. Remove the wings and remove these bulkheads from the fuselage. Using a
#31 drill, carefully drill the bulkheads for the clamp mounting bolts. We also
recommending drill lighten holes to the wing formers to reduce weight.
11. Sand the fuselage where these bulkheads will be glued. Wipe down with
lacquer thinner or equal.
12. Reinstall these bulkheads back into the fuselage along with the wings.
Tighten the clamps onto the wing tubes. Check all alignments and when
satisfied, tack into place with 15 min epoxy. When cured, remove the wings and
proceed to glue the bulkheads in place with a bead of AEROPOXY on both
sides. Allow to cure overnight.
.

NOTE: Check to see that your turbine mounts fit the rails properly side to side. If
you need wider rails, consider cutting new ones from birch ply and install or you
can add filler pieces to the outside of the existing rails BUT you will need to glue
a 1/16” splice plate under the joint area to reinforce the glue joint.
14. Locate and Install the Turbine Mounting Rails as shown using Hysol.
15. Locate the parts shown that makeup the forward equipment tray.
16. Assemble the 2) tray mounting ears to bulkhead F3 using CA+.

17. Assemble bulkheads F2, F3 and the tray. Place into the fuselage and slide
forward into position. Check fit to fuselage and sand F2 & F3 as required to
obtain proper fit if needed. Remember that the TRAY is removable.
17. When satisfied with fit, reassemble F2, F3 and tray and tack ONLY F3 into
place with 15 min. Epoxy, when cured install F4 and F5. (Tray removed for
clarity)
18. Locate the nose gear mounting plate and install the 4) “T” nuts. Trial fit
between F2 and F3. When satisfied with fit, glue into F2 and F3 and glue F2 to
fuselage. Finish with Hysol 9462.

19. Install the Latches into the REAR of the Main Hatch by locating the pin holes
first. Then mark the location of the Lever on the top surface of the hatch and
remove. Repeat for both latches.
20. Trial fit and check operation. When satisfied, glue into place.

21. Using the Black Magic Marker, coat the end of the hatch pin, install hatch,
pull back and release striking the fuselage identifying the location of the pin. Drill
a 1/16” hole at this location. Repeat for both latches.
21. Locate a hole in each FRONT corner of the Main Hatch for the mounting of
the brass tube pins. Epoxy the pins into each hole allowing ¼” to stick out. Allow
to cure. (NOTE: Carbon Fiber Pins can be substituted for the supplied Brass
Pins)
22. Now transfer the location of the pins to the fuselage as shown, then drill to
accept the pins. This completes the Main Hatch Installation.

23. Prepare to mount the canopy frames by Drill a #22 hole to receive the Brass
pin. (NOTE: Carbon Fiber Pins can be substituted for the supplied Brass Pin.)
24. CA Pins into place.
25. Mark and drill into Fuselage to receive the pins.

26. Shorten the latch pin by pulling the latch back, holding and cutting the pin
LEAVING 1/16” pin REMAINING.
27. Locate the latch pin opening as you did for the Main Hatch.
28. Locate and cut the latch lever slot into the Fuselage. Mount the latch using
CA tack. Than finish with Hysol 9462.
29. Mark the Canopy Frame as you did for the Main Hatch using the latch pin,
drill to receive the pin. Mount the Canopy Frame and check fit.
30. Install the Canopy only after you have completed your painting using silicone
or RC-56 canopy glue.

31. Lightly sand the backside of the F/G fuselage inlet pieces and the mating
surface of the fuselage, then using CA+ or 5 Min. Epoxy, glue the fuse. Inlet
sections into place.
32. Locate the Left and Right air inlet ducting and trial fit them into the fuselage
and mate to the backside of the fuselage Inlet pieces just installed. The internal
inlet ducts are to be removable to service the fuel tanks.
33. Fabricate a 1/8” ply saddle that will fit against the Wing tube bulkhead. Mount
in place with CA+ or 5 Min Epoxy. Be sure NOT to have excessive glue on the
forward face of the joint as you want a tight fit against the bulkhead when
mounted. After gluing into place, cut this saddle in half along the Inlet split line.
This will allow for each inlet to be removed independently for ease of install and
removal.

34. Trial fit and secure the Inlet dusting into the bulkhead as shown using #2 x
3/8” Socket Head Sheet Metal screws.
35. Trim the Inlet ductings to suite your installation.
36. Remove the bell mount from the pipe first. Slide the pipe from rear forward.
Use servo screw to secure the pipe to engine rail. Use metal heat shield mounted
to the engine rail to protect all your air hose and servo wires.

37. Adjust the engine location to insure that the FRONT EDGE of the pipe
Bellmouth Inlet is EVEN with the REAR of the Engine Exhaust nozzle. Inserting
the engine nozzle too far into the tailpipe can result in high engine EGT’s.
38. Fuel cell and UAT installation Diagram

39. Install fiberglass tail cone. Use micro screws to secure the cone.
40. Install nose gear door, air cylinder and closing valve.