Build Articles
HET-RC - F4D Skyray EDF
By Carl Tulanko
June 15, 2005 - 11:24:01 PM

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01 - Here's the box...
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02 - ... and a couple items I ordered to make the model fly.
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03 - Opening the box reveals typical HET-RC packing, with wings taped inside to prevent damage from movement. Take your time and carefully pull off all the tape before removing the components. This will prevent damage that can be caused if you use a knife.
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04 - Wings were removed from the inside panel then the panel was lifted, revealing the airframe, parts bag, cockpit assembly and thrust tube.
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05 - The "F4D Skyray ARF"... this is how it comes.
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06 - Tape was carefully and completely pulled off of each bag and then each item was removed. Pulling off all the tape first makes sure a piece doesn't accidentally stick to the covering and damage it.
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07 - The major components... top quality craftsmanship and covering!
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08 - The fan compartment is viewed from below.
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09 - HET-RC listened to their customers... this tow hook location is easy to find!
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10 - The cockpit assembly. Once again, improvements were found as the canopy has trim lines well marked in the molding.
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11 - The front of the vertical stab had a small rod protruding.
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12 - A view underneath reveals this is a rear canopy latch... a nice touch!
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13 - Elevon servo covers are extra thick, heavy duty plastic.
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14 - Removing the cover reveals the servo compartment.
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15 - My Hitec HS-81MG Metal Gear servos will fit, but need a bit of coaxing.
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16 - The "bag" of components.
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17 - Control surfaces have heavy duty hinges... they are removed before mounting the wing panels.
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18 - A small slot was extended to remove the wire pulling thread.
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19 - The 1/4" stick has to be pulled/snapped loose from inside as it is tack-glued in place during shipment. Once loose, remove it through the enlarged slot.
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20 - Removing the wire puller thread.
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21 - A dental pick or other device was used to break the stick loose, then used to remove it.
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22 - Removing the puller.
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23 - The other end of these strings are pre-threaded to the front cockpit area of the fuselage by the factory. They are used to pull the servo extension wires from the cockpit area through to a servo in each wing.
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24 - I decided not to mount the receiver in the cockpit area, so the RED pulling thread was removed.
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25 - A dual conversion high quality receiver is recommended for this model.
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26 - The receiver will be mounted next to the fan unit, similar to the HET-RC FA-18 Hornet. This will eliminate the need to route three long servo extensions and leave more room in the cockpit for batteries.
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27 - Make a mark 1/4" or more from the front wall and a second mark for the length of your receiver.
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28 - Area that needs to be removed for the reciever.
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29 - The location was cut out.
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30 - Horizontal cut made.
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31 - Receiver area cut out.
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32 - Sand the area to fit your receiver.
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33 - The Hitec Electron 6 reciever fits well for a 1 7/8" long hole.
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34 - A 1/2" square block was cut to extend the platform for the receiver.
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35 - A block was inserted...
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36 - ... and dropped into place.
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37 - An exacto knife was used to "spear" the block and hold it in place from the wing servo hold on the side.
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38 - Thick CA was applied to the block.
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39 - the exacto knife was used to position the block, making a nice and wide area now for the receiver to be taped.
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40 - The receiver fits easy enough for a child to install.
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41 - The cover will need to be opened so it fits over the receiver.
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42 - Cover was marked, then the area was cut.
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43 - The fan shroud was temporarily installed to mark mounting areas.
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44 - Two marks were made from the rear of the cover... one mark at 1" and another at 2 1/4".
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45 - For our friends overseas, this would be 25mm and 58mm.
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46 - The other side of the hatch was marked.
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47 - A 1/8" or 3mm wide strip was measured between the lines.
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48 - ... and a line was drawn.
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49 - This area needs to be removed in order for the lid to clear the fan shroud mounts.
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50 - Balsa removed from both sides.
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51 - Another view... hatch is ready to use.
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52 - Beginning the build... foam is removed from the wing for servo wires.
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53 - The foam was pushed out.
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54 - Then the area filed.
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55 - Picture showing wires routed through the wing.
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56 - Close-up showing wire routed through foam wing.
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57 - Beveling the edges of the dowels for easy insertion.
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58 - End beveled.
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59 - both dowels ready
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60 - Dowel is inserted so it is flush with the inside of the wing .
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61 - The outside of the dowel is marked for position.
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62 - Marked dowel ready to install.
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63 - Forward dowel, marked at 1/2" dead center.
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64 - Forward dowel marked.
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65 - 5 minute epoxy applied to forward dowel.
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66 - Forward dowel inserted in fuselage up to the line that was drawn.
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67 - Rear dowel with 5 minute epoxy inserted in fuselage up to the short line.
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68 - Excess epoxy was cleaned up with a paper towel and some denatured alcohol, then left to set.
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69 - Mixing up the good stuff for wing mounting.
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70 - Epoxy applied to wing spar.
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71 - Epoxy applied inside slot, then spar inserted. The spar can go in either way, making installation easier.
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72 - Spar will bottom out inside the fuselage.
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73 - Applying epoxy to the fuselage root.
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74 - Fuselage with epoxy applied.
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75 - Epoxy next applied to wing spar slot.
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76 - Epoxy applied to entire wing root and dowel holes.
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77 - Wing with epoxy ready to install.
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78 - Installing the wing
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79 - Wing pressed down until flush.
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80 - Excess epoxy was removed with paper towel soaked in denatured alcohol.
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81 - Joint cleaned and T-pins used to hold wing in place.
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82 - Wing was mounted flush to the top of the fuselage and a small ridge was evident at the bottom, but will be fine.
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83 - Edge view of installed and pinned wing.
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84 - Clean up the excess epoxy from the servo well.
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85 - Wing pinned and epoxy left to set.
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86 - Wing installed.
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87 - A piece of 1/2" brass tube is sharpened by shaving the inside with an exacto knife.
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88 - Brass tube inserted through servo access holes.
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89 - Brass tube is used as a drill to make a hole for the servo wires.
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90 - Tube was angled upward so it would come out inside just above the horizontal runner.
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91 - Tube came out just above the runner.
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92 - Hole drilled for servo wires.
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93 - Another view... you can see the fan tube through the holes.
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94 - Rear guide dowel installed in other fuselage root with 5 minute epoxy.
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95 - Guide pins installed and glue is set.
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96 - Slow cure epoxy applied to wing root.
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97 - Second wing installed just like the first.
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first. 98 - Epoxy was cleaned up.
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99 - Excess epoxy squeezed out of the top.
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100 - Wing cleaned up and pinned just like the first. Then placed aside so epoxy can set.
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101 - The power plant... a Wemotec MiniFan 480 and Mega AC 16-15-2.
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102 - Torch used to heat up the adapter so it would slide over the motor shaft. DO NOT push this adapter all the way on or the back of the fan will bind against the shroud when installed.

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103 - Set screws installed with some Loktite.
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104 - Other set screw installed... note the shaft base is not against the motor. It had to be pulled away about 3/16" for fan clearance.
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105 - Installing the motor in the shroud.
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106 - Motor intalled.
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107 - 3mm screws are used to retain the motor. The fan unit comes with 2.5mm screws, so you will have to buy 3mm screws if needed.
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108 - Fan installed, followed by washer and nut.
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109 - Shaft adapter slotted for screwdriver.
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110 - Bolt slotted.
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111 - With shaft slotted, a screwdriver can hold the shaft still while the nut is tightened.
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112 - Nut installed.
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113 - Fan hub installed...
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114 - ... and retained with supplied screw.
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115 - Wiring the motor... 3.5mm connectors added to motor ends.
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116 - Connectors installed.
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117 - Heat shrink added.
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118 - Soldering the connectors to the electronic speed controller.
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119 - Socket connectors installed.
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120 - Heat shrink added.
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121 - Extended power wires soldered to the ESC.
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122 - Assembly wired and fan balanced prior to installation into airframe.
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123 - Wings glued and model ready for color.
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124 - Hinges removed to mark them.
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125 - Center lines are marked down the middle of each hinge
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126 - Center lines are drawn... the lines are drawn up the shorter side, allowing more surface area to bond when installed.
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127 - NOTE: THE BUILD STOPS HERE. The next few steps show my method of dressing up the model with a bit of color.
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128 - Control surfaces stripped so I can recover them with white.
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129 - Areas I wanted to add color to were stripped of the original covering, leaving 1/8" - 3/16" for overlap.
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130 - A stripped area shows some of the quality of build by HET-RC at the factory.
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131 - Nose color applied.
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132 - Tail is stripped and black leading edge added.
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133 - Red added and being trimmed before cleanup.
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134 - Adding some color to the vertical stab.
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135 - Stab being ironed.
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136 - F4D Skyray with the color scheme I decided to use.
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137 - Skyray covered in color... NOTE: THE BUILD WILL CONTINUE FROM HERE
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138 - Install a hinge into the fuselage up to the drawn line.
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139 - Hinges installed. I used the control surface to make sure the hinges aligned correctly.
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140 - Hinges glued and tugged to make sure it is in solid.
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141 - Hinge glued and tugged to make sure it is in solid.
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142 - Elevon installed.
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143 - Other elevon installed.
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144 - Make sure it is even with the wing tip.
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145 - You should also not be rubbing the fuselage here at the root.
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146 - A piece of masking tape was marked at center, then 10, 12 and 15mm for down throw. The stab is designed to throw down only so far.
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147 - Holding the stab with one hand, 5 - 8mm throws are what is called for. I went to 10 - 12mm so the stab wouldn't bind if pushed a little too far.
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148 - Holding the fin down, thin CA was applied to teach hinge. Make sure the fin is even with the wing tip because once the CA is applied, it's too late.
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149 - Other side of hinge getting some CA.
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150 - Hinges glued in place.
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151 - This step may not be necessary for everyone. A 3/32" x 1" x 7/16" piece of ply was cut from some scrap.
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152 - Piece glued behind ply fan mount, extending the mount to the rear former. I plan on using FAUP's and wanted to make sure I could move the fan more if needed, so the mount was extended.