Archive for May, 2009

So He Wants to Build a Plane

Saturday, May 30th, 2009

The following is a guest post…

Mary here, talking to all of you who ladies whose husbands have said, "Honey, I want to build a plane in our garage."  You're understandably freaked out right now – I was when I found out that building airplanes is one of Matt's favorite hobbies.  Don't fret!  This is a doable project!  However, you shouldn't go into it blindly.  Here are some things to expect from an airplane-building husband.

This is a huge endeavor. OK, you probably already figured that out.  But let me give you a little perspective.  Matt began building the plane in Spring 2005.   I started pharmacy school the following fall.  I graduated this month, but Matt's plane is still a year away from flying.  This is not for the flighty (no pun intended).  This is like having a baby.   The plane will be a major part of your lives for years, if not the rest of your life.  (Thankfully, there are no 3 AM feedings.)  And much like a baby, a plane will require you to invest a good deal of money and space.  Consider:

  1. You'll need workshop space.  For a lot of you, this means you'll have to give up parking in your garage.  You also might find an airplane canopy on your guest bed, or ailerons in your spare room.
  2. It gets expensive.  Builders need rivets, rivet guns, clecos, pliers, drills, screws, an air compressor, wires, deburring tools, wrenches, countersinks, fiberglass material, hoses…  It adds up, and will continue to add up throughout the project, as he'll need to get more and more stuff. The UPS guy and I are pals.
  3. As I mentioned above, it takes a ton of time.  If you want to be at his side 24/7 either be prepared for him to never finish the plane or go out and help him. Which brings me to my next point…

Building an airplane is not just something for him to do.  This can be a family project. You don't have to be out there every second – despite what the pictures on Matt's blog might suggest, I'm not out in the garage every time he is.  It will go a lot smoother if you get involved.  There are certain tasks that are a lot easier to do with a second pair of hands, and everything that gets done puts you a little bit closer to flying.  Even going to the workshop for a few minutes to look at the neat new thing he built can be a big morale boost.  And men, this is a two-way street.  Make a deal that for every, say, 30 minutes, your wife spends on the plane, you spend that much time on something she likes, or do some of the household chores for her, or stay home with the kids while she runs errands.  And speaking of kids, they can help too.  But use your good judgment; letting your toddler handle a rivet gun is probably a bad idea.

You'll meet a lot of new people in this process. Your husband will probably make friends with other builders through VAF, the EAA, and local airports.  Take advantage of this! For one thing, it gives him someone else to talk shop with when you get sick of the airplane stuff.   For another, a lot of these guys are married too, and you and the builder's wives can commiserate.  Airplane people are some of the nicest, most interesting people you'll ever meet.  Far-flung airplane pals can also tip you off to places to visit on your next vacation and maybe even get you a free lunch somewhere.  (Thanks Doug!)

You need to be his #1 cheerleader. I'm not asking you to put on a short skirt and wave pom-poms [aww. -ed.] unless you enjoy that sort of thing, [woohoo! -ed.] but airplane building can be a frustrating process, and your husband probably won't enjoy every part of it.  (See also: Matt and fiberglass)  Help keep him going during the difficult parts.  If you can't help, come down and talk to him while he builds, or let him bounce ideas off of you.

You may also need to keep him on task. Again, not every part of this is enjoyable, and it's easy to get discouraged, especially for someone who has a demanding job.  He may, like Matt, suddenly think it's more important to work on one of his other projects than the plane.  While sometimes that's necessary (the plane can wait if Junior needs help with his science project), too much of that can mean he loses momentum and before he knows it, he hasn't worked on the plane in a month.  Planes that don't get worked on don't get done, and we want these planes to get done.  I once had to threaten Matt with no slushes for the rest of his life if he didn't give up his extra projects and just focus on getting the plane done.

And finally, have a sense of humor. So your friends all think you're crazy, you can't walk into your house without tripping over a just-delivered box of parts, and your guest room looks like an obstacle course.  So what?  You and your spouse have a fun (hopefully) relationship-strengthening project you can do together, and even if you're only minimally involved, you always know what he's up to.

– Mary

Audio input jack

Monday, May 18th, 2009

I wish I had one of the new GMA 240 audio panels. The 240 has a stereo input jack right on the front panel, which the much more expensive GMA 347 that I have does not. So to enable my passengers to plug their iPods into the panel and hear the audio in their headphones, I had to track down and wire a separate 3.5 mm audio jack – one of the fancy switching kind that uses a separate set of contacts when the plug is inserted. This will let me use the single set of input pins on my audio panel for both external audio and XM music from the GDU 375 MFD.

I made this little bracket to mount the jack on, since the threaded part of the barrel is way too short to go all the way through my 0.090" thick instrument panel:

The mounting hole is drilled oversize to accommodate the enlarged plastic shoulder on the jack body. This insulates the jack from the metal panel, to prevent the possibility of a ground loop (which is important for quiet audio).

A mylar washer under the nut keeps things insulated there too:

The bracket is attached to the panel with a pair of #4 screws, and the hole in the panel is oversized to keep the nut from shorting to ground. Functional and looks good too.

Six wires are soldered to the five contacts on the jack… two separate pairs of left and right channels, and one common low connection. The two sets of wires also share a common shield.

The little ear on the bracket is for an adel clamp that supports the wires:

Here's what it looks like installed in the panel:

My dad was in town for Mary's graduation, so I enlisted him to help test the audio quality.

Now this is some flying music:

I don't have an XM antenna hooked up yet, but I verified the MFD side of the audio wiring using the 1 kHz factory test tone:

I noticed that this bundle of wires behind the subpanel is starting to get pretty close to a couple of subpanel rib flanges. I will probably put some cat grommet on the flanges, and tie-wrap some plastic conduit around the wire bundle too.

12V socket

Monday, May 18th, 2009

I installed a simple 12-volt socket on the passenger side of the panel, for powering miscellaneous devices:

I used 14-gauge wire and a 10A fuse for this socket. A rubber boot over the positive terminal protects against shorts.

What do you think, should I use this as my backup GPS?

Mary graduates

Sunday, May 17th, 2009

Congratulations to Mary on earning her doctorate!

She's been working a whole heck of a lot harder on her education than I have been on my airplane. That may have something to do with the reason why she got done first, and she definitely earned it.

And yes, the girl in the background does have a giant pill on her head.

Headset jacks

Sunday, May 10th, 2009

This weekend's main task was to connect and install the pilot and passenger headset jacks in the brackets I'd previously made. Each occupant has separate jacks for headphone audio and microphone, plus a separate Bose jack that combines phone and mic audio plus power for my nice ANR headsets. Add in the wiring for the push to talk button, and you end up with a lot of wires that all have to be carefully soldered to the jacks. Of course all the wiring is shielded too, and you have to join multiple shields together in a couple spots. The wires that come attached to the Bose jacks are 26 gauge, which is just incredibly small and difficult to work with. I think I'm still slightly cross-eyed from sorting out all those tiny wires.

Here's the same thing tied into a nice bundle and installed in the bracket. Note that I used heavy heatshrink to support the connections.

I left generous service loops for future maintenance:

The audio connector on the GMA 347 is by far the busiest connector in the whole panel. The bundle of shielded wires going to this connector keeps getting bigger and bigger. Luckily there's just a handful of connections yet to be made on this particular connector. Man, I really overused the word "connector" in this paragraph.

I made Mary come downstairs and help me test my handiwork by talking back and forth using a pair of headsets. It all worked! Not quite Alexander Graham Bell, but satisfying anyway.

I thought I would knock out the headset jacks in an hour or two and then move on to other things… instead it took me two afternoons to finish it all. Just a lot of fiddly little things to get hooked up and working right.