Archive for the ‘Misc’ Category

Moving

Sunday, August 23rd, 2015

Sorry for the lack of updates lately, but this time I have a good excuse: We are moving! Mary got a job offer that promised to be a very positive step for her career, but which also happened to be on the west coast. She took the job, moved out west, and is renting an apartment. Eventually we intend to look for a house in the Pacific time zone, but in the short term the airplane project will have to be moved cross-country and then put into storage for a while. Fortunately, I have a new friend out west who's agreed to allow me to put my airplane in his hangar.

In the meantime, I am still in the midwest packing up everything and getting ready to sell the house. I suppose it's only fitting that I'm the one left behind to do the packing, because – either by weight or by volume – the majority of the stuff in our house is the responsibility of yours truly. This whole process has caused me to realize that I'm a total tool hoarder and a complete packrat for anything mechanical. For instance, these shelves used to be absolutely chock full of tools and airplane parts, but in terms of my total shelf space they only represent ten percent of the total hoard, tops. I still have a lot of work to do, but a whole lot of stuff is already packed away.

I filled up the fuselage with as many bulky-but-lightweight items as I could – carpet, seats, interior panels, fiberglass fairings, etc. I also temporarily reinstalled as many components as possible, to reduce the total number of items that have to be moved. I think this is actually the first time I've had both the canopy and cowling installed at the same time. I have to admit, it looks pretty cool.

To allow it to fit on the truck, I had to remove the horizontal stabilizer from the fuselage. That's just as well, because I don't think it would have fit through the single-bay garage door otherwise, thanks to the annoying post in the middle of the garage. I left the vertical stabilizer attached, in order to help soak up the load from the tailwheel mount. The forward spar of the vertical stabilizer is temporarily secured to the fuselage with a block of wood and some clamps.

I used miniature furniture dollies under the main wheels to allow the fuselage to move sideways and snake its way through the narrow garage door. In this photo you can just see one of them under the left main tire.

Can I count this as the airplane's first grass landing?

After more than a decade of building, I had hoped to be able to fly this airplane soon, and it is in fact really close – but not close enough. So, time to call for the big truck.

The trailer currently in use by Tony Partain's trucking company is pretty neat – all kinds of clever attachment points to tie down airplane parts.

Unfortunately the wing stand wouldn't fit on the truck, so I'll have to donate it to a local builder and figure out something else for the other end.

Here's how the wings are transported. It's all very secure, and it keeps them out of the way of the fuselage as it's rolled inside.

This is the last time I'll see my airplane project for a while. It was a pretty heavy feeling seeing it disappear around the corner. Still, our new living situation should eventually allow me to spend more time working on finishing this project – after a few months to get re-settled, that is.

To be continued…

Magnetometer

Sunday, February 1st, 2015

The magnetometer is a little gadget that measures the strength and direction of the local magnetic field, which allows the AHRS units to figure out their current heading, among other things. If you read the installation requirements literally you might think that there's nowhere in the airplane you can mount it to meet every one of the requirements, but in the RV-7 a good spot is the F-714 aft deck, just ahead of the horizontal stabilizer. Garmin makes a mounting plate you can use for this, although anyone who has progressed this far ought to be able to knock one together from scrap aluminum in no time at all.

I happened to have one laying around, so after some careful alignment I drilled the fastener holes through the aft deck:

The magnetometer mounts into this combination nut ring and alignment fixture, which I riveted to the plate with AN426AD5 rivets. A rivet that big is way overkill for such a lightweight piece, but that's the size of the countersink you're given so that's what you've got to use.

I bought some brass screws and locknuts from McMaster-Carr, and used them to attach the plate to the aft deck. Brass because you want to avoid putting ferrous material (e.g. steel screws) next to your magnetometer. I could have used rivets here, but I wanted this plate to be removable in case I ever need to reach my hand down in there to do maintenance work. Also I really didn't want to crawl back into the tail again to set the rivets.

Test-fitting the magnetometer to determine where to terminate the wires:

I put a tie wrap anchor on the aft face of the F-709 bulkhead and used it to secure the the connector for the magnetometer wiring:

Wider shot of the aft fuselage with magnetometer installed:

Happily, the magnetometer came up and started talking on the first try:


Compressor repair

Saturday, May 10th, 2014

Ever since I bought my air compressor, a factory-overhauled unit from Campbell Hausfeld, the pressure regulator has been broken in a very specific way. When set to the On position, it would run the compressor automatically as designed, topping up the air pressure whenever it dropped too low. However, it would also do this when the switch was set to the Off position, thus making a mockery of the entire concept of having an On/Off switch. I knew all along what the problem was – a little plastic bit inside the regulator housing wasn't quite long enough to interrupt a set of relay contacts – but the inertia of doing nothing about it made it pretty easy to ignore for a very long period of time.

When we went on trips I would turn it off by flipping the breaker at the fuse panel, which is a well-intentioned idea (avoid burning the house down if the compressor springs a leak) but not particularly a well-executed one (using a breaker as a switch is generally considered bad form). This generally led to simply leaving the compressor in a "live" state overnight, which sometimes caused it to cycle in the wee hours of the morning when the falling temperature caused the pressure to drop below the set point. Although you can't hear the compressor outside our house when the garage door is closed, it is unfortunately sited more or less directly below our bedroom, and is quite audible from in there. It always would wake me up, but I'm a light sleeper so everything wakes me up (here's looking at you, annoying loud neighbor). However, once or twice the sound was even of sufficient intensity to wake Mary from her customary log-like slumber, thus making her quite grumpy indeed. So that was more or less the last straw.

Anyway, I finally got around to replacing the regulator with a $37 part from Pacific Air Compressors:

I'm happy to report that it was a quick and easy job, and now the compressor works as designed in all modalities. Most importantly, I no longer wake up to discover that I'm in the doghouse before I've even found my trousers.

I am alive!

Sunday, August 18th, 2013

I guess it's been long enough since I've updated my build log that people have started to worry. Thanks to those who have written to see if I am still alive… I swear I really have been working on the airplane! (although a bit sporadically) No pictures this time, as I have been having some computer and camera issues. Hopefully a nice big update soon. Stay tuned…

Tool interlude

Monday, October 15th, 2012

So yeah, it only took a few weeks for me to break down and buy a real milling machine. Like you didn't see that coming.

Actually I hadn't intended to get one right away, but I was unexpectedly lucky on eBay and got a very nice 12" Sherline mill to go with my 3.5×17" Sherline lathe. Judging from the few parts I've made with it so far, I can definitely see that a dedicated machine is a lot nicer and more capable than a lathe with a milling conversion attached.

The mill seems to have hardly been used at all, but since it's at least fifteen years old and doesn't seem to have gotten much TLC during its life, I decided to strip it down to its component parts so I could clean and lubricate everything. I also replaced the AC cord and switch, and added a power indicator safety lamp as I did with the lathe. After putting everything together, the mill worked a lot smoother and with less backlash, so it was worth the effort.

Then while I was at it, I tore down the lathe to individual pieces too, and gave it the same tune-up treatment. Then for some reason I decided to really get crazy and add DRO scales to it too. That was more challenging than I initially thought, and took a couple weeks to really get sorted out, but it did give me a chance to use the new mill to make real parts. And now that the lathe is back together, it too works better and has digital readouts to boot. (I may add DRO to the mill as well, but if I do I'll almost certainly take the easy way out and buy a kit!)

Hopefully this will all come in handy for the airplane project. Don't worry, I haven't totally forgotten that I have one of those too.