Backfitting positionlights to ARF modells

I prefer to build my models completely by myself. But sometimes I buy also an ARF model made of balsa or composite - if I like it very much. As a rule, I finally modify the ARF planes and provide them with additional details such as cockpits, painted sheet metal joints and rivets, etc.


For civilian aircraft models, position lights are a must for me. But how do you retrofit luminaires, including the required cables, in the edging of a fixed balsa wing? And without ruining the film completely ...


I just perform the following:


Before anythng else I try to get an idea of the wing structure through the existing openings in the surface. Very often, the ribs already have holes and recesses for weight reduction, which you can take advantage of. I decide for the optimal and shortest possible course of the required cables to the next opening.


First, I drill carefully at the desired position of the lamp from the outside in the edge bow, usually with a 5 mm drill. In doing so, I try by eye to specify as precisely as possible the direction within the surface for the later course of the lines and drill as deep as the drill used permits.


For the second step, I prepare an auxiliary tool by looping several saw-teeth at one end of a sufficiently long brass or aluminum tube with the same diameter. These saw-teeth are used to make a makeshift drill bit. Then I use the auxiliary tool as a drill in a cordless screwdriver and drill carefully with little pressure through all necessary ribs to the desired exit point. In this case, special care is required so that the makeshift drill does not pierce the film at an undesirable point before.


Once the hole is done, loosen the tube from the cordless screwdriver without pulling it out of the hole. Now you can push the required cable through the tube and then pull the tube out of the surface. Hold the cable at the other end to keep it in place.


Now the hardest part has already done. Very bright, large format SMD LEDs are a good choice as position lights. For example, I have had very good experience with CREE HighPower LEDs of type MX6AWT-A1-0000-000E51 (with a 4.7 Ohm resistor at 5 V) for the bright strobe pulse of an Anti Collision Light (ACL). If you glue these to the front of a short wooden pin that fits into the hole and guide the two cables along the left and right, you can easily glue the entire unit into the hole. With short flash effects, one can neglect the heat development of the LED, for continuous operation, the LED needs cooling. This type is bright enough to be still visible in the sunshine.

The following pictures show examples of such an ACL.

The model of the Cessna 421 is also a good example for further modifications. The ARF design consisted only of the white and blue cover and a bow with the larger lettering as stickers. That looked a little bit boring. All the other details in the photos were therefore added later - with relatively little effort:

  •      all the thin black lines and rivets of the window frames (CD markers)
  •      silver window frames (paint pen, beware - it fasten smears)
  •      black edges on nose strips of wings and tail (black cover film)
  •      lighting
  •      Rope antenna at the bottom of the fuselage (black rubber cord and toothpick)

In the overall effect, the plane looks much better in my opinion.