16 Oct 04 - Light bulbs and a Pitot Mount


Well, let's see what's on the to do list for today. First, while reading Dan Checkoway's site, I noticed that he crammed 100 W lightbulbs in his Duckworks Landing lights instead of the standard 55 W bulbs. We'll have to run heavier wire in order to get away with that but we haven't run any wire yet, so deciding to do this now is ideal - we don't have to start tearing wires out in order to accomplish this. I have no desire to spend the additional $350 to get the super-bright HID landing lights, but spending a few bucks to almost double the wattage of the bulb sounds like a more economical way to make it better.

Secondly, it would be nice to get the pitot mount finished up. We'll talk about that after we get done with the lights.


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Used battery ($4) for testing the lights, etc.
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$5 each at Advance Auto Parts.
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Comparison: 55 Watt (left) and 100 Watt (right). Woop-de-doo, they look the same.

Finding these lights was actually more of a challenge than I thought - CarQuest and Auto Zone both didn't have them. Though to be perfectly fair, they're a pretty weird part. The 100 W halogens are so bright that you're only supposed to have them for off-road use, so they're not a replacement for headlights.

However, it all worked out well - the trip to the other auto parts store wasn't a total waste as they had a old battery that they sold us for $4 (donated into their coffee kitty, actually). Well, for $4 it's worth it, even if it doesn't hold a charge very long. Brought it home, put some water in it, recharged it, and suddenly we have a way to test the lights. I suspect we'll be using this sucker lots, even if we have to recharge it every week.


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Landing light off.
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Landing light on! Woo hoo!
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Hole for the pitot mount.

The thing we want to do is start thinking about getting the pitot mount on the wing. Here's the basic order of the steps that we followed . . . this seemed to work pretty well, but use these directions at your own risk:

  1. Get a general idea of where you're going to have to drill the hole in the wing skin. This will probably mean clecoing the brace on the wrong side of the skin and tracing it. (Trace both the hole for the pitot mount and the big square that is the outline of the brace.)
  2. Get some sort of a hole in there for the pitot mount, but don't get too close to the edges. We used a drill and a pair of snips, but I'm sure there are more elegant (and probably more expensive) ways to do this.
  3. Cleco everything together on the wing. (This is the step that we're doing in the above far right picture.)
  4. Match drill the holes.
  5. Take it off the wing and finish the hole for the pitot mount. There's actually good reasons for doing it in this way: this way, if you file it with the pieces clecoed together, the holes are going to line up. If you just trace it, and then make the holes as large as they should be, it may not line up exactly.


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Now the holes are match drilled.
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Clecoed on but now off the wing - now we can make the holes line up exactly.
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After a bit of filing. Getting closer, but not there yet.

As attentive readers may notice, we're about to not follow the directions. The directions for the rivets that connect the main bracket to the L-bracket also go through the skin of the wing. We decided to not do this for two reasons: First, if we did it that way, we wouldn't be able to attach these parts until we clecoed the entire skin on, and I'm not quite that patient. Also (and this is the real reason), the night before when we were drilling the rivet holes in that part, I didn't realize that the rivets were going to go all the way through to the skin, so I just sort of eyeballed it. Having un-lined up rivets on the outside of the airplane would stink, so let's not do that.

Plus, I think it's just a lot easier this way, and I'm certain it will be strong enough, as we didn't leave any rivets out, we just didn't run them through the extra layer of alumininum. (Though it wouldn't be a bad idea to put some proseal or something on this when we attach the skin for the final time, just to keep this from vibrating around.)


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Finished filing. Here's the pitot mount through the holes. Lines up pretty well!
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Riviting the main bracket to the l-brace. Because the wing skin is going to sit on top of this, we still had to use some flush rivets.
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The L-brace riveted to the wing rib.
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Finished! Well, except for riveting the bottom skin on, but we'll do that later.
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The whole wing, showing placement of the pitot tube mount.

Time to shove the wings aside. We're not really done, but this is as far as we are getting on the wings for now. Here's the reason for this: First, I'm still debating whether or not to put a wing leveler in this airplane. I'm leaning towards yes, so there's a large motivation for not putting the final wing skin on, as this means I won't have to slap the servo on the very end of the wing. Secondly, I haven't even started thinking about strobe lights, wires, and pitot plumbing, so let's leave that last wing skin and wingtip off for now. Because that skin supports part of the flaps, too, this means we're not putting the flaps on at this point, too. So what's left on the wings is:

So these really aren't done. But that's as fas as we're getting for now, so it's time to work on the fuselage!


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