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This blog was originally started to talk about flying. It has gone done many different roads; I've talked about cars, and computers, and soldering, and my cats. That's all fine, but I think it's time for a flying post.
I went flying a week ago, October 19. I mean really flying. Several weeks ago I joined a flying club. Three weeks ago I went flying with an instructor and got signed off to flying the club's Cessna 150 solo. A week ago Sunday, I took my first solo flight in the club's airplanes. My main purpose was to get out and do some semi-cross-country flying. That flight was a lot of firsts (or almost firsts). My first time flying any of the club's airplanes solo My first time flying that plane solo My first time landing or taking off solo at any of the airports I visited My first time taking off and landing solo on a turf strip My first time since November 3 2007 flying ANYTHING solo My first solo flight outside an airport traffic pattern since August 19, 2007 when I flew back from getting my license.
The weather was glorious. It was clear and cold and the visibility must have been at least 25 miles. Here's my route:
and from any point I could see the mountains that corresponded to the features of the entire route. For a while during my training, I had trouble spotting airports from the air until I was almost on top of them. It wasn't a problem on October 19. I could see airports from 15 miles away. One aspect of real flying that really can't be duplicated in a simulator (particularly on a home computer) is how far you can see on a clear day. (By the way, the above sectional photos were blatantly stolen from SkyVector--I love that site. They now have a flight planner!)
The navigation part was trivial. My approaches weren't very good; I really need to go out and do touch-and-go's somewhere and get my pattern dialed back in, and practice soft-field approaches. But I didn't screw the landings up too badly and in each case I knew what I'd done wrong.
I was going to go flying today but I was tired and I really didn't feel like it. But hopefully more flying stories here in the near future. There also might be posts about washing airplanes, if I get to that.
Sometimes you need to take time off from the fun stuff and work on the infrastructure of your life. Cleaning the dishes, or whatever comes under this category, but sometimes there are more long-time-scale things in that category. Some of the lights in our garage aren't working.
Yesterday I managed to get up in time to go to the store in town that stocks fluorescent light bulbs to get new ones. They're fairly long, about 8 feet
and unlike most fluorescent bulbs, they only have one contact on each end:
Putting new bulbs in the fixture didn't help; the whole light emitted a really loud buzz when I turned the lights on. So the problem must be in the fixture. Some googling led me to this page on troubleshooting fluorescent fixtures. I had thought that fluorescent bulbs were self-sufficient nowadays, but that's not the case. There's still a "ballast" device that transforms the voltage somehow.
The fixture in our garage has a flat plate in the middle that ties things together.
The silver things are clips that hold the side covers into the center plate. Removing all the covers reveals the wiring
and the ballast and where the wires come in from the electrical panel.
So the circuit is simple enough, I just have to find someplace local where I can buy a replacement ballast of the proper specifications.
Successful so far: 1) Now know infinitely more about one topic than I did before 2) Exercizing the take-it-apart-and-figure-out-how-to-fix-it part of the brain 3) Add another skill and checklist item to the maintaining-the-house-you-own list.
I'm building a James-Bond style self-extending instrument panel for my Beetle. The last time I talked about it, I was at the carboard mock-up stage.
Last week I actually bent metal. Here's the panel piece clamped and ready to bend:
The rotating panel piece:
This is the part that will contain the instruments, and rotate.
Here's the chassis piece after bending. This part will attach to the car, and the panel piece will attach to it.
This weekend I started installing electrical parts. The panel installed in the chassis, with motor installed:
Components installed in the back of the chassis.
The thing in the center is a 7806 6V rectifier (the motor is a 6-volt motor). The two relays connect the terminals of the motor to ground and +6V; one to turn it one way and the other the other.
There are two limit switches near one end of the rotating panel that cut off power to the relay that drives the panel in that direction.
The electrical part isn't quite finished, but here's the panel wired up for testing.
Here's a look down the side; you can see the way the drive shaft couples to the rotating panel.
Yesterday, I got a round panel hole cut for the oil temperature gauge, and I've drilled holes in preparation for cutting the openings for the voltmeter and the charging current meter.
Sorry about the gap in posting; the end of September is the end of the federal fiscal year, and so as usual at this time of the year, I have the Annual Progress Report to finish and send off. I have to send off my bits by tomorrow, so that'll be done.
I went out the other day to get spark plugs for the new head that I got for my Beetle. It got me interested in the different types of spark plugs and what they're for. The place I ordered the new head from told me that the spark plug holes in new heads made in Mexico are deeper than the originals (most likely because the originals would eventually crack there). So for the time being, I will need to have two plugs original length in the left side of the engine, and two longer ones on the right for the new head:
Spark Plug specifications are really complicated, and every company has a completely different numbering system to indicate the various features of their plugs. I did run across a cross-reference online that was useful. Many of the differences have to do with what type of thread is on the plug, or what the seat is, or whether or not the plug has a resistive core to cut down on radio frequency interference. However, there's one specification that is very important to the longevity of the plug and the running of the engine, that's the "heat" of the plug.
Since spark plugs ignite the fuel-air mixture in the cylinder, they are automatically one of the hottest parts of the engine. They get fairly hot, and it's important for them to be able to dissipate the combustion head as the engine is running. However, it's also important for the plug to not get too cold, either. One of the consequences of being hot is that there's a lot of chemical reactions going on right there. There is lots of cruddy stuff that tends to plate itself on all the parts of the combustion chamber, including the spark plug. The plug being hot keeps the deposits burned off so that it still acts efficiently as a spark gap. If the plug runs TOO hot, though, it ends up being an ignition source just from its heat, which is very bad, and it tends to be eroded away and not work at all, which is bad too.
Here are a couple of close-up views of those plugs.
The tip of the plug (the sort of button-thing in the middle) is the part that gets the hottest and needs to burn deposits off. You'll notice that the plug tip sits at the end of a long ceramic cone that goes up into the plug. The length of that code determines the "heat" rating of the plug. A "cold" plug is one that has a very short cone, which conducts head to the metal barrel of the spark plug and thus to the rest of the engine relatively well. A "hot" plug has a very long cone and conducts heat more poorly, and so tends to run hotter. The ideal case is that the plug is from 500-800 degress F while the engine is running. If the engine runs hotter, then the plug needs to be "colder" so that its final temperature ends up in about the right range.
My new favorite VW parts place has a very nice Bosch plug page that gives just the options that are most likely relevant for people driving VWs. There are basically four Bosch spark plug codes that are relevant: W8AC for stock beetle engines, W8CC for standard engines with long threads, W7AC for short thread engines that run hotter (higher compression, perhaps), and W7CC for hotter engines with longer threads.
In addition to their primary function, being an ignition source, plugs also have a seconary function of being a diagnostic tool. They are a piece of the combustion chamber that can be removed without taking out the engine, so if something (mixture, for instance) is dreadfully wrong, you can look at the plugs to see if they contain clues.
For those of you keeping track at home, I discovered in September that the long-running problem with my Beetle is that the right side cylinder head in the engine had been machined too much, reducing the combustion chamber volume and causing those two cylinders to have too high compression ratio, and thus running too hot. A secondary issue is that the valve guides seemd to not have been tight as they should have; the valve stems were sooty.
So I ordered a new cylinder head, from one of the big VW parts vendors. Unfortunately, this was a lesson in who not to order parts from. I've ordered lots of stuff from them before. Some of it fit and worked, some of it didn't. I shouldn't have taken the chance with something as important as the cylinder heads, which is after all a critical component of the engine.
[I currently have 4 cylinder heads in the garage that fit the engine. To give them names: head A: head that came off right side of engine. Machined down too far, valve guides leaking head B: head from left side of engine. Working just fine; will put back on head C: new head from big VW parts dealer. Not enough venting, valve job poor head D: just got this one, venting good, valves good.]
I realized as soon as I got it that head C didn't have as many vent holes above the combustion chamber as heads A and B (photos below). This concerned me, but I was determined to get the engine together, so I went ahead and started measuring the combustion chamber volume. I discovered that one of the exhaust valves sealed so badly that the water I was using the measure the chamber volume leaked out fast enough that I couldn't get an accurate reading. I took the valve out and discovered that the valve seat wasn't ground correctly; it was more than twice as wide at certain points than others.
At that point I decided that it wasn't worth dealing with it, and I should just get yet another head. I'm sure that if I ordered a head from Gene Berg, that it would be perfect, but their heads are very expensive (almost $400). So last week, I ordered a head from VW Parts, which came yesterday. This is head D.
I'm happy to say that the venting on D is the same as my original heads. I put spark plugs in the holes and put some water in the chambers last night. One exhaust valve leaked very slightly, but probably not enough to disrupt measuring chamber volumes.
Now for some pictures. Here's a photo of head B with light behind it:
The light shows where the venting is. This is looking at the head from "below", if the head was on the engine. The airflow in the assembled engine would be coming at the camera. If you divide the head into three regions vertically, the top region is the combustion chambers and their fins, the middle part is the valves and the intake and exhaust tubes, and their fins, and the bottom part is the valve gallery where the rockers live.
Here's the same photo with lines showing where some of the things are. The red box at the top is roughly where the combustion chamber is. The green lines coming up from the bottom to the combustion chamber is roughly where the intake passage goes. The blue lines define the exhaust passage; at the left end of the head you can see the two studs sticking out where the exahust bolts on. The fat purple line is about where the exhaust valve stem is, and the fat yellow line is where the intake valve stem is. The areas circled in cyan (light-blue-ish) are where air flows through the heads to cool the exhaust valve and the exhaust exit area. I have read that these are very important, and eliminating them is bad.
Here's head C, the "new" one that I've decided not to use. You can see the cyan areas here, the venting near the exhaust valve and passages has been greatly reduced.
And here's head D, that I got from VW Parts a couple of days ago. The venting is equivalent to the original head, so that's what I'll be going with.
