Primer
Lights
Fuel Gauges
Blind Rivets
Electric Trim

Primer

I have read many posts and web articles about the pros and cons of priming a homebuilt, and the opinions range from "priming is unnecessary" to "priming is the only way."

I am not trying to cut corners, but I think that the overly complicated multi-stage priming processes which have been suggested by some could needlessly extend the build time to a point where it would not be a fun and educational exercise. Therefore, I set out to find a simple primer which would provide at least a small margin of protection against corrosion without putting me through a rigorous set of extra tasks.

I think I have found a product that will do the job. It is Sherwin Williams 988 self-etching primer. It comes in a spray can, which should reduce set-up time.

http://www.sherwin-automotive.com/products/show_product.cfm?product=7565

Here are some links to people who are using this stuff on their projects:

http://vondane.com/rv8a/paint/
http://www.tabshred.com/moe/getstart.htm
http://rv.nicknaf.com/rvproject/20021114.html

Primer Update: 5/6/2004

My procedure for priming the empennage parts was to first scuff the parts with ScotchBrite pads, then clean the parts with Acetone, and then (finally) spray the self-etching primer. The preparation work turned out to be a lot more messy, and a lot more trouble than I had anticipated. As a result, I have changed my procedure for the wing parts.

I decided that if I was going to have to clean the parts anyways, I may as well use Alumaprep. And, if I was doing the Alumaprep, I may as well go ahead and Alodine. So, the new procedure is as follows:

First, clean off any sticky substances (like stickers or tape) with Acetone. Next, working outdoors I spray on the Alumaprep/water mixture and scrub the part with Scotchbrite pads. Next, I rinse the part with a water hose and then hang the part in the garage so it can dry. Now I am ready for the Alodine. I either brush it on or dip the part, and after three minutes I rinse it with the water hose. Once again I let it dry. Finally, I prime with the self-etching primer. Although the self etching stuff is not really necessary after all of this work, I still do it because I want to maintain consistency with the parts I may need to quickly prime in the future.

The bottom line is that this new procedure doesn't take much more time than the old scuff-and-prime procedure, and I prefer wet scuffing to dry scuffing.

Primer Update: 5/11/2004

I ruined a gallon of Alodine. I figured I was doing the smart thing by working out in the nice spring weather. What I noticed about halfway through the process was that the parts didn't seem to be getting as dark as they were at the start. By the end of the batch of parts I decided I needed to find out what was happening. Was the aluminum causing the Alodine to wear out?

The answer? Don't use Alodine out in the sun. It is sensitive to the sun, so being out in the sun ruins it. So, I ruined a gallon of Alodine, but at least I don't have cancer!

Lights

I plan to add lights to the plane, so I investigated the options and found that there are many ways to go about it. One issue is the fact that with the big bubble canopy, you don't want a strobe mounted on top of the plane. Another is the added drag that can come as a result of placing lights on the fuselage.

Vans sells a light package which contains three combination lights: a red with strobe for the left wingtip, a green with strobe for the right wingtip, and a white with strobe for the back end of the rudder. This is currently the setup I plan to use.

System Six is the one I am currently planning to use.

Lights Update: 1/4/05

I bought my lights from CreativAir. Bill VonDane sells a complete lighting package which includes position, strobe, and landing lights. The only thing not included is the tail light, which I bought separately from Van's. The position lights are LEDs, and everything fits inside the wingtips.

Lights Update: 2/12/05

I have finished assembling the light kit from CreativAir. Check them out.

Fuel Gauges

One of the strange things that I first noticed while I was working on my Private Pilot's License was a distrust of all fuel gauges. This started with my first instructor. He told me that the plane I was flying in at the time had really bad fuel gauges so you should never even look at them. So, I always used a stick to measure the gallons of fuel in the tanks. After I passed my checkride I started flying 172s, and again the fuel gauges are not very reliable.

Based on this experience, I decided that I want my plane to be a little different. I want to be able to look at any instrument and get some useful information from it, including the fuel gauges. I have come to find out that fuel level accuracy starts with the sending units in the fuel tanks themselves. Also, apparently most fuel gauges are limited by the dihedral of the wings. I can deal with only seeing the fuel gauge move if the fuel level is below 15 gallons in each tank. What I don't want is some mechanical foul-up with a sending unit causing the gauge to read incorrectly.

Bottom line: I have decided to install capacitive fuel sending units in each tank. These are solid-state devices which have no moving parts at all, and theoretically should last the lifetime of the plane. The downside is that these units require a more expensive fuel gauge, but the one I plan to use is really nice, putting the ones in the old Cessnas to shame.

Here is some information about the Electronics International fuel gauge.

Update 2/12/05: The GRT engine monitor will display fuel information, I only need to buy the senders. I won't be using any other fuel gauges.

Blind (Pop) Rivets

At times the plans call for blind rivets to optionally be used in place of solid rivets where a bucking bar or squeezer cannot easily reach. I know most builders would prefer a solid rivet over a pop rivet, but I cannot see why I should spend any time worrying about these "optional" pop-rivets. I mean, I have a friend who is building a Sonex, and the whole plane is covered in pop rivets, so they are certainly strong enough. The two issues I can think of may be that they weigh a bit more and they cost a lot. Well, if we are only talking about a few here and there, it seems that the time savings would overcome any additional cost considerations, and the weight is probably so small a difference as to not matter.

So, the bottom line is that I will be using blind rivets whenever the plans say I can. The factory demonstrators use them, so I will too.

Electric Trim

After figuring out that Van's ships the RV-9A with electric flaps as a standard feature, I started thinking about the space the trim cable and control would occupy. Initially I had decided to use the manual trim because of the simplicity, but as I weighed the options I came to the conclusion that it sure would be nice to have the trim controls located on the stick, and since the servo provides position information automatically, I won't need a sensor to provide visual feedback of the trim position. Ray Allen sells a nice position indicator, and some of the engine monitors display trim status as well. So, I ordered the electric trim servo so I could install it while I am building, rather than waiting and having to do a retrofit.