Putting Things Together (final assembly)
Page Three

5/4/2011; getting ready to paint the tail and wings

After painting several projects in the shop, I've learned how overspray can find its way to nearly everything if left uncontrolled. Here is the booth that will prevent the interior of the shop from being coated with silver PolySpray. The frame is a combination of 1x2 and 2x2 pine sticks and 1/2" ply gussets. The frame is held together with drywall screws for easy assembly and disassembly. Three 10x20 1-mil plastic drop cloths form the canopy and are stapled to the frame. The shop fan blows into the back of the booth to provide some flow-through and the open end is pointed at the backyard.

The booth is 8 x 7 x 16, plenty large enough for the wings.

Holding the bits and pieces of airframe can be awkward, but here is an easy way to paint both sides of the horizontal stab. A couple of pieces of tubing slip over the ends of the stab tubes and the trailing edge is attached to the sawhorse with two cable clamps. One side will be shot, then the assembly is flipped over for the other side. Shooting the stab horizontally will reduce the possibility of runs and sags.

The tail and wings have received two brushed coats (one cross coat) of PolyBrush sealer in preparation for the PolySpray. The underside of the tail gets one cross coat of silver, and the upper surfaces two cross coats.

Here is the rudder with masking for the checkerboard. The "correct" way is to do this in two stages so the lines can be as straight as possible, but I masked everything at one time so the rudder could be shot once and ready for the airport. With a little planning the squares wrap around the edges and match the ones on the other side of the rudder. The masking paper inside the squares doesn't show well in the photo.

Four hours masking, 60 seconds spraying....

Wing in the booth. The wings get one light cross-coat of silver on the bottom and 1 1/2 light crosscoats on the top. This is a lightweight finish that should provide reasonable UV protection.

This is the fixture on the root end of the wing that allows it to be easily rotated by one person. The outboard end rests on a sawhorse.

Wings painted and at the airport.

A bed extender that fits into the trailer hitch receiver was welded up and a cradle cut that fits the leading edges. The root fittings were secured to a fixture in the front of the bed.

5/27/2011; weight and balance

Here is XL-58 on the for-real aircraft scales. The plane was carefully leveled and datum marks were placed on the floor using a plumb bob.

The empty CG is favorable and the plane will be within the envelope at all operating weights.

XL-58 as it flew during the summer of 2011.

Update April 2012: XL-58 has a new color scheme.

The original Polyspray silver finish was serviceable but not very visible in the air. My original intent was to paint the XL yellow but the cost of several coats of Polytone was beyond what I wanted to spend. Besides, I didn't want to rebuild a spray booth, relocate the airplane, and endure the noxious fumes.

Latex house paint has been used for painting ultralights for at least twenty years. The uninformed will talk about latex weighing an excessive amount but actual finished weight of latex vs PolyFiber is very close. Latex is also extremely flexible and can be an excellent UV blocker. After all, the stuff is designed to protect our house from ridiculous climate extremes for twenty years.

But a huge advantage of latex is the absence of fumes, water cleanup, and application with a roller. No paint booth or spray equipment required! And last but certainly not least......cost. The latex system is a fraction of the cost of PolyFiber or similar systems. I just can't justify spending 20% of the cost of a simple airplane on finish materials.

Fortunately latex will adhere aggressively to the silver Polyspray that was already on XL-58. I decided to incorporate the silver into the paint scheme to reduce the amount of additional paint. I still had part of a quart of Polytone Black that was used on the rudder checkerboard so that was used for the black accents on the tail and wings. It was flowed on as two very wet coats with a foam brush.

Two coats of Valspar exterior latex primer were rolled onto the silver in preparation for the Naples Gold Valspar Duramax semi-gloss exterior latex. The primer contains titanium dioxide which is an excellent UV barrier and sticks aggressively to nearly anything. The primer was thinned with water (~20%) and applied with a 4" white foam roller. Two coats were needed to get a reasonably opaque shield over the silver. If I had started with the latex primer on the naked fabric instead of the Polyfiber process this would have been a much easier job. I will certainly go all latex next time. One quart of primer was sufficient as a base for the yellow.

Don't be concerned with the appearance of unevenness as the primer is applied, it dries to a perfectly smooth and flat finish. Some builders add Flowtrol to latex to assure the finish flowing out evenly but I didn't find it necessary. Others will thin with windshield wiper fluid but I found plain water to work just fine. Two coats of thinned yellow were applied with a 4" white foam roller. A nice aspect of rolling the paint is how only one strip of tape is necessary to mask the painted areas--no need to add yards and yards of plastic to protect everything from overspray! Some technique is required but anyone who has done careful painting in the kitchen or living room should be able to do a wonderful job of painting an airplane. Just be prepared for visitors to the hangar to be incredulous about you rolling the paint onto your plane....

Because I wasn't able to completely avoid paint bleeding under the paper masking tape (I found automotive fine-line tape wasn't much better on the weave of the fabric) I applied silver automotive trim tape to the paint lines to make everything look finished. Overall, I am very pleased with the results. The thinned latex paint flows out very nicely and dries with a low-luster gloss that should easily repel bugs and dirt.

Materials (paint purchased in aviation department of Lowe's):

1-qt Valspar exterior latex white primer
2-qt Valspar Duramax exterior latex semi-gloss
6- 4" white foam rollers
1-roller handle
6-2" foam brushes
6-aluminum baking trays used as paint trays (local grocery store)
1-roll painter's tape
3-rolls automotive pinstripe tape (Advance Auto Parts)

Background information:

An excellent article on using latex paint for finishing a FlyBaby.
Interesting article on how latex holds up under extreme environmental conditions.
Another test of the UV blocking ability of latex paint.

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