Build Articles
HET-RC - F-20 Tigershark EDF
By Carl Tulanko
February 15, 2006 - 07:22:07 PM

01 - The F-20 as it arrived from Warbirds-RC. It is very well packed.	02 - The HET-RC ARF Minifan 480 sized F-20 Tigershark out of the box	03 - The major components of the model. It is very similar to the HET-RC FA-18 in construction and covering
04 - Model comes complete with pre-strung red cord wire pullers	05 - The Elevator area shows bolt mounts for easy alignment	06 - The fan area with blind nuts pre installed for fan mounts
07 - The other end of the red cord wire pullers. These ports are used for Aileron servo leads, ESC power wires and Receiver antenna	08 - A view of the ducting from the tail end	09 - Aileron Servo bays are already cut under the covering
10 - Wing cord is 13/16" thick, which makes is a good candidate for Retracts	11 - Time to build...Start by trimming away the covering from the Wing Spar and Aileron Servo holes	12 - Holes cleared of covering
13 - The wing spar is inserted with the angled edge facing downward in the fuselage. It is keyed inside so you can't get it wrong	14 - Wing is temporarily installed	15 - A ruler is rigged to measure wing position
16 - Build up a piece of masking tape with about 4-5 layers. This will be used as an anchor for the wing root position	17 - Rear of wing is positioned 1MM from the bottom of the fuselage. The "built up" masking tape is then placed on the side of the fuselage to keep the wing from shifting up (left)	18 - Wing is supposed to be 1mm up from the fuselage at the rear (left), then flush against the bottom where it's chord dips (left of thumb) and then it curves upward to a center of 10mm at leading edge

19 - A marker is used to draw spar position	20 - Wing position drawn	21 - Covering is cut away so the wing can be mounted to the fuselage
22 - Covering is then removed	23 - Aileron servo wire hole is opened up a bit	24 - Marker lines are removed with Denatured Alcohol
25 - Marker lines removed	26 - Monokote Iron is used to seal the edges of the removed covering area	27 - Epoxy is applied to the fuselage and wing spar hole

28 - Wing has epoxy applied and spar is coated with epoxy. Note that due to the much wider wing chord, holes were not drilled in the wing

29 - Wing is installed on the fuselage

30 - Rear of wing is pinned to keep the position at 1mm from the bottom and hold it up against the masking tape jig. Also note the wing is flush to the bottom of the fuselage near the center. It was left like this until the epoxy cured.

31 - Other side of the wing, shown with rear butted against the masking tape jig. Note that the wing has a slight dihedral, so it is ok if it seems to lean slightly	32 - Excess Epoxy was removed with Denatured Alcohol before it set	33 - Once the wing set, extra epoxy was used to fill any small gaps. The excess was removed with a paper towel dampened in alcohol
34 - Other wing is positioned and shown being marked. The procedure is repeated for the second wing	35 - Covering is removed	36 - Aileron hole has been opened and iron is sealing the edges of the covering to the fuselage side
37 - Epoxy is applied to the wing, spar and fuselage side, then it is installed	38 - Note that once again it is pinned in the rear to keep it at 1mm, then the center is flush with the bottom of the fuselage	39 - Vertical Stab spar was not shaped correctly, so it was trimmed to taper at the forward section. TIP: you can re-use old pieces of covering removed from wing chord to re-cover shaped areas

40 - Forward stake re-shaped to a more scale like appearance

41 - Rear of Fuselage was marked at the center top for Vertical Stab installation

42 - Mark shown at top center

43 - Forward section of fuselage marked at center of turtle deck

44 - A line is then drawn from the turtle deck to the Fuselage rear mark

45 - Center line drawn for Vertical Stab

46 - Covering is cut away about 1/8" on each side of the center line

47 - Covering is removed for good glue purchase

48 - Iron used to seal the freshly cut edges

49 - The bottom 1/2" of covering is cut from the Vertical Stab

50 - Covering being removed

51 - Edges of covering sealed with an iron

52 - The "front" of the Stab is marked to insure it is installed correctly

53 - Stab is test fit to the Stake

54 - A hobby knife assists with keeping the stake open while epoxy is applied

55 - Epoxy is applied to the inside of the stake rather than on the Vertical Stab. This will keep the upper seam clean and free of glue when the Stab is inserted

56 - Stab is inserted into the Stake until it is flush with the bottom of the Stake

57 - Clamps are used to hold the stake in place while Alcohol is used to clean up excess epoxy that squeezed out

58 - Vertical Stab and Stake Assembly completed and drying. Note the position of the Stake; the recessed area is at the front of the assembly

59 - A center mark is made on the underside of the Vertical Stab at the rear

60 - Pins are installed front and rear to keep the fin aligned and centered on it's marker lines. Check the fit for gaps and lightly sand if necessary

61 - Epoxy is applied to the bottom of the Vertical Stab Assembly and to the Fuselage

62 - The Vertical Stab is placed in position and pinned in place while glue sets. A square on a board works great to insure it is perpendicular to the Fuselage

63 - Pre-drilled holes are punched in the Horizontal Stab with a pencil

64 - Horizontal Stab shown positioned above it's location	65 - Supplied bolts and washers are installed in the pre-drilled holes	66 - The Horizontal Stab is temporarily installed using the supplied hardware
67 - A marker is used to mark the location of the fuselage sides on the Horizontal Stab	68 - Cut about 1/16" inside the marked lines to remove covering	69 - Covering is being removed from the top of the Stab. Note: SAVE THIS COVERING! It can be reused to cover Aileron covers later in the assembly

70 - Marker lines are removed with Denatured Alcohol

71 - Covering edges are sealed with an iron

72 - Horizontal Stab ready to glue in place

73 - Extra covering is trimmed away from the Horizontal Stab area on fuselage edges

74 - Covering is then removed

75 - Edges are sealed with an iron

76 - Epoxy is applied to the fuselage edges, rear lip and center spar. Be careful not to get glue in the blind nut holes on the center spar

77 - Epoxy applied to the trailing edge of the Horizontal Stab

78 - Stab is then installed on the Fuselage

79 - Bolts are used to hold the Stab in place

80 - The Stab is positioned flush against the rear lip of the Fuselage, then pins are installed to hold the Stab down to the Fuselage edges...this is important...make sure the fit is flush with no gaps

81 - Excess epoxy is removed from the rear

82 - Excess epoxy is removed from the top of the Stab and Fuselage joint

83 - Horizontal Stab Installation completed

84 - Front of Fuselage drilled for Antenna wire tube

85 - Inside of fuselage is drilled for Antenna wire tube. NOTE: You should always ground test as this antenna run may not work well with your radio

86 - Hole shown drilled under the front dashboard on the right bottom side

87 - Hole is drilled in right rear for Antenna wire tube

88 - Red cords are used to pull wires through fuselage

89 - Antenna wire tube installed from the front

90 - Receiver antenna wire is tied to the fuselage RIGHT SIDE red cord (Note that the fuselage is inverted)

91 - Antenna wire is pulled through the fuselage into the cockpit area. The red cord works great!

92 - Rear of tube is pushed through hole at rear cockpit former, then the front is marked for trimming

93 - Antenna wire tube is cut to length

94 - Antenna Installed	95 - Inside of nosecone is roughed up with 60 grit sandpaper	96 - Inside is shown sanded
97 - Epoxy applied to front edge of Fuselage	98 - Epoxy applied inside of Nosecone	99 - Nosecone installed on Fuselage

100 - Excess epoxy cleaned up

101 - Nosecone left vertical pointing up so it will run down to the Fuselage and create a fillet. Nosecone shown below is finished

102 - Fuselage Airframe Build completed

103 - Fuselage Airframe Build completed Most of what you will need to complete the electronics. 12Ga wire, hardware and batteries not shown

104 - Black Power Wire tied to red cord

105 - Wire pulled rearward through the Fuselage

106 - Red wire taped to the black and pulled through

107 - Power wires shown exiting hole in rear of Fuselage

108 - Tinning the power wires

109 - 3.5mm Wire sockets used and installed

110 - Heat shrink tubing installed on sockets

111 - Power Wires completed at rear end of Fuselage

112 - Connectors soldered on the ESC

113 - Matching connectors installed on the motor. Note the "Plugs" are installed on the motor instead of the wires from the ESC/battery; this is to prevent shorting of the power source if components are unplugged. Always use sockets on the power side of the wires and plugs on the component side for safety

114 - Motor plugs get some heat shrink to prevent the possibility of shorting

115 - Plug installation on motor completed

116 - It is important to balance the fan, especially for a 700w 4S power setup. A High Point Balancer is shown below, but any cheap magnetic balancer will due

117 - 3MM bolts are required for motor mounting in the fan assembly. Note this assembly is for the Wemotec Minifan 480. If you use another fan, follow the manufacturer's instructions for assembly

118 - The shaft adapter is placed on the motor shaft

119 - The supplied set screws are installed with just enough drag to allow the adapter to be moved up and down the shaft under some pressure

120 - Motor in installed in Fan Shroud

121 - You can install the two 3mm bolts temporarily to hold the motor in place

122 - Fan is installed and pushed down until the rear of the fan bottoms out on the shroud surrounding the motor

123 - Fingers are pushing against the fan to keep it bottomed out on the Shaft Adapter, while the Adapter is pulled out slightly to give about a 1/16" clearance between the rear of the fan and the front of the motor housing at the edges. This spacing will prevent the fan rear from rubbing against the motor housing

124 - Fan is then carefully removed

125 - Motor is removed from the motor housing area on the Shroud

126 - Locktite is applied to the set screws one at a time and they are each re-installed and tightened

127 - Once both set screws are tightened, use a Q-Tip to remove all traces of the Locktite, otherwise it can attack the fan shroud plastic

128 - Locktite is appied to the motor threads with a toothpick. Never apply Blue Locktite to the bolt threads, or it can attack the plastic in the shroud. Another solution is to use "Green" plastic safe Locktite

129 - Motor is installed for the final time in the Fan Shroud

130 - The two 3mm x 6mm mount bolts are installed and tightened to hold the motor centered and in place

131 - Fan is installed on the shaft

132 - Washer is installed next

133 - Aluminum nut is installed and made finger tight

134 - The shaft is pushed through a piece of paper, then a slot is cut dead center in the shaft with a Dremel. Paper is used to keep any filings away from the motor while cutting

135 - Slot shown cut into the shaft, about 3/16" deep

136 - A screwdriver is used in the slot that was just cut, holding the shaft while a 10mm wrench is used to tighten the aluminum nut

137 - Fan assembly completed

138 - A 2" long piece of heat shrink tubing is placed over the three ESC wires

139 - The ESC wires are connected to the motor

140 - Temporarily connect the receiver and motor, turn on your radio and start the fan unit to check direction. If it is spinning the wrong way, reverse any two motor leads to the ESC

141 - Once you set the motor direction (toward the ESC), use a heat gun and shrink the tubing around the leads. This will help prevent them from comming loose during normal flight

142 - Leads sealed and heat shrunk

143 - ESC is tie wrapped in place to keep the wires tight and somewhat areodynamic, so they don't fly around loose in the duct

144 - Top view of the completed power plant assembly

145 - Fan Assembly is installed in the Fuselage

146 - If you have difficulty sliding the fan into the duct, slightly bell the mouth of the duct with some fine sandpaper. Pic shows supplied mounting bolts being installed. Note the inside where balsa was cut away on the sides so the fan could be installed

147 - Double sided tape added to Hitec Electron 6 FM Receiver

148 - I installed the bottom cover plate with screws, then used a ruler through the rear of the fuselage to position the receiver and push it down in place. Note that it has clearance so the Crystal and leads will not interfer with the duct tube

149 - Cover screws are removed

<