Roee Kalinsky's RV-7A Project

2010.06.22: (0.0) The airframe per Van's design does not make any specific provisions for the installation of landing lights ^[note].  However, several 3rd party kits exist, one of which -- the Duckworks kit -- has become the de-facto standard, and this is the one I'm using.

[Note: As of a recent design change, Van's latest wing tips include provisions for landing lights.  However, I have the older-style wing tips, and in any case I prefer the Duckworks design for a multitude of reasons.]

The Duckworks design calls for a cut-out in the wing leading edge skin in the outboard-most wing bay.  This is where weakening the wing box a bit has the least effect (Van's approves of this), and where the light will cause the least amount of reflection off the prop disc.  A shaped acrylic lens closes the cutout, and an adjustable mounting bracket for the lamp fixture is mounted inside the wing bay, right behind the lens.  The original Duckworks design used parts from an automotive driving light (55W H3 halogen bulb and a rectangular reflector), which was a very elegant and cost-effective solution.  Other versions were later made available, including a more powerful round aviation-style PAR36 bulb, as well as automotive HID lamps.  The beauty of the Duckworks design is that all these lamp styles are easily accomodated, and even easily interchangeable / upgradeable by just replacing the adjustable mounting bracket.  In my case, I'm planning on using LED-based landing lights (either from AeroLEDs or of my own design), and so I simply purchased "blank" mounting brackets from Duckworks, without any of their lamps.

I opted to install two landing lights, one in each wing.  This will give me 1) better illumination for takeoff/landing/taxi operations, 2) a measure of redundancy in case one light fails in flight, and 3) the possibility of a wig-wag flasher capability to make my aircraft more visible in flight.

2010.06.22: (0.0) So let's get to it.  Currently with the left wing temporarily attached to the fuselage, this is a convenient time to do the left landing light.  I started by marking the leading edge cutout outline on the wing.  The Duckworks kit comes with a paper template and dimensions on where to locate it relative to the top skin joint over the spar and the rivet line of the inboard rib of the outboard bay.  I measured and marked the rectangular outline on the wing based on the dimensions alone, and then placed the paper template over it and used it to mark the outline of the rounded corners.  I also took this opportunity to mark the locations of the mounting screws, using the pre-punched backing strips as a guide over the paper template.  Note that with the dimensions given, about two thirds or more of the cutout ends up on the bottom of the wing.  This looks suspicious at first, but I verified that that's the correct position (the light gets aimed down slightly).  Definitely a case for measure twice cut once!  And now for the slightly scary part of cutting the big hole into a perfectly good wing.  I started by drilling a hole near the upper right corner, and then used a milling bit in a rotary tool (i.e. cheap Dremel knock-off) to do the initial cut.  I kept it about 1/8" from the final outline at this point.  I then worked it toward the outline with a sanding drum in the air drill, then some touch-ups with files, and finally I polished it nice and smooth with a scotch brite drum in the air drill.  Came out great!

2010.06.23: (0.0) Drilled #40 pilot holes for the 6 screws that secure the lens in place.  Used the marks I made previously to position the pre-punched backing strips, which I used as a drill guide.

Did the initial trimming of the acrylic lens.

2010.09.02: (0.0) This entry describes work from a while back...

Finished fitting the lens and related hardware, although I may still choose to trim the side edges a bit more to facilitate insertion and removal when the lamp mounting plate is in place.

The paper templates provided to locate the bolt holes in the ribs were printed a bit out of scale, as measured against the hole spacing on the mounting plate.  The holes on the mounting plate flanges are deliberately cut oversized to allow for adjustment of the light geometry, so it's somwhat forgiving of the bolt position.  But as it is easy enough, I re-scaled the templates on a xerox machine to get it as close as possible.  Another more annoying issue, the mounting plate is about 1/4 inch too narrow to fit properly between the ribs.  Argh...  So I made some 1/8" spacers (one for each side of the bracket).  I cut them such as to prevent interference with the stiffener beads in the rib, which actually would have interfered had the mounting plate been the "correct" width.  Everything about this installation is just a little "off" like that... but at this stage in the project I know this is par for the course.  Easier to just make it work than to bitch about it.