Painting: Right Wing

Here's the masked off root rib with cardboard to fit. Used rib jig to trace it.

One of many sanding sessions, been using 320 grit wet for primer and 400 grit wet for topcoat...

I had overall better luck avoiding orange peel on final topcoat this time, by reducing mixture 40-50%. I also made sure to visibily flow the paint on. The down side, due to the thinner mixture, I had lots of runs occuring on the near vertical areas, such as LE/TE spars when the wing was laid horizontal. I quickly cleaned them up with a clean wet sponge, with only minimal negative effect. Forget about spraying wings vertical on the stand, as runs occured galore. So had to spray horizontal, which of course set up more horizontal area for crap to rain down on during curing process. I still much prefer final product: nice smooth wet finish. Think I've got a method now to get reproducible results. On to the left wing....

Painting: Horiz Stabilizors, Elevators, Rudder

I finished spraying the tail feathers. First pic shows them being positioned horizontally on saw horses.

Next pic shows what first coat of primer looks like on one side.

Here is pic after first top coat.

Here is pic following second top coat. I hung all the pieces at this point, thinking I could shoot everything at once and minimize contamination on coat. This worked well, but I neglected to consider air pressure of spray on pieces which resulted in them becoming moving targets during spraying. Ended up with orange peel on all of them, but in the interest of time, I decided to press on. Thankfully, I'm done dealing with saw horses and hanging stuff on wires as now on to the big stuff mounted on the rotisserie stand. Will have much more control now.

I have the recurring problem of orange peel developing only on the second pass of each top coat. Never the first one. I currently suspect maybe I'm applying first pass on to heavy. Hope to resolve during shooting of wings, which are next.

Painting: Flaps and Ailerons

Wow, this has been some trial and error learning experience. I started with small control surfaces for practice and went through the whole process from two primer cross-coats to two top coat cross-coats and a WHOLE lotta sanding in between.

Here is what I've learned from experience and consultation with Superflite:

1. Superflite Primer: Primer is mixed as follows: one part primer base, 1 part catalyst and 0.5 part flex agent. All pieces to be sprayed were placed horizontally on saw horses, so as to maximize penetration of primer into weave matrix. Also, to further enhance penetration, I thinned paint 25% with reducer on first pass to reduce paint viscosity. One half hour later I then sprayed the next pass in perpendicular fashion to previous pass, which resulted in one complete cross coat. The cross coat was allowed to dry one night and was then wet sanded next day with 320 grit sandpaper. You do not want to let dry more than 48 hours. The second cross coat was applied in same manner and sanded. I used a delivery pressure of 20 psi to the gun (static, trigger closed) and a 1.5 mm tip on the gun.

Here are pics of primer application...

2. Superflite Top Coat: This was mixed at: 3 parts topcoat to one part catalyst. This mixture was then reduced 25% to reduce viscosity. The first 3 passes were sprayed horizontally on saw horses, while the last one was sprayed vertically. Since the last one can not be sanded, I wanted to minimize potential for dust contamination. I increased delivery pressure to 20 psi at the gun when trigger open. I opted for applying this material on thicker, as lighter than primer and more flexible.

Here are action shots of topcoat application....

Finally, here are final products....

Problems encountered: included contamination onto paint surface. I found I reduced this considerably by draining my compressor of water frequently and changing out my airline dessicant/filter on regular basis. I also started using a tac rag or cheesecloth over the surface right before painting to remove dust. Prior to this I would clean surface with a fast drying methanol compound. I found spraying stuff vertically also helped tremendously and will do at a minimum on last pass of topcoat. Spraying vertically increases the risk of runs, but have had no problems with runs yet...

Orange peel of topcoat was another major problem encountered. It's called this because the paint resembles the surface of an orange. I have minimized this problem by increasing air pressure to 20 psi when trigger pulled and thinning topcoat material 25%. Not too worried about it, however, until final topcoat pass, as sanding will take care of it between passes. I prefer the lower gun pressure as it reduces overspray which equals waste and fog in the paint booth. Worried about creating explosive atmosphere in the paint booth coupled with my cheap Walmart fan as an ignition source. I will heat up garage with furnace and then turnoff during painting, spraying in a batch type manner during winter conditions.

Wicking is another problem encountered. This occurs when primer applied to virgin fabric underlain by structure. The paint gets wicked through the fabric leaving weave openings. The way to prevent this is to brush thinned U500 over these areas first.

Reusing premixed paint stored in freezer. I have regrettably done this twice and will never do again. First time was with primer and when used next day it gummed up my entire gun. I was then told topcoat material is less volatile and takes longer to catalyze so tried again with bad paint results.

"Eruptions or blackheads" on paint. I thought I had this going on at first but think what I saw was from contamination particles. This can occur when first pass not allowed to cure before second pass sprayed on. Volatiles from first pass can vent through second pass creating sharp bumps on the paint.

Painting: Paint Booth Prep

Not a whole lot of plane production this past month, due to camping, out-of-town trips and company over. I did manage to get the paint booth built, however. Will be running a high volume low air pressure (HVLP) spray outfit. Never done anything like this before, so a little nervous. Supplied breathing air will come through from garage door side and paint exhaust will be through window-mounted fan. As soon as I get a free evening, I'll get started. Think I'll start with the ailerons. Also took some time getting tooled up and configured for painting. Needed a larger 33 gal volume tank compressor and spray gun (DeVilbiss). I calibrated the gun settings by spraying with water (similar viscosity to paint) on cardboard.

As a side project this summer, I built the boys a treehouse. Originally considered Walmart playset, but with cost of lumber down was able to build this for nearly same cost.

Covering: Right Wing: Tape

YIPPEE! Covering is finally entirely complete. I began in early December, so over 9 1/2 months! First pic shows attachment of rib tapes at LE for marking of edges on fabric for glue application.


Next couple pics show glue applied to tape width.



Here's me attaching rib tape to glued areas with thinned MEK.


And after ironing pinked edges and cleanup of residual glue with MEK, here are completed pics.

Next, setup paint booth and prepare for HVLP painting.

Right Wing: Covering: Patches

The exit rings, inspection rings and lexan strips were glued and riveted onto the right wing, respectively. Patches were glued over the rings. Following are pics of wing bottom. Some sweltering August nights were encountered, therefore, pardon the topless pics.

Right Wing: Covering

Both top and bottom panels are now installed on the right wing. Top panel went on first, here you can see glued edges around top LE and TE spars.

Next couple pics show thinned glue application to sheet metal surfaces which dissolves and wicks underlying glue into fabric weave.

Here is pre-tautened top fabric.

Next pics show glue application to areas to receive bottom fabric panel. Two coats of glue were applied.

Here I am applying thinned glue to fabric LE of bottom panel.

Final tautening of wing fabric to 350 degrees with an iron. Gotta love August in the UP, warm nights and no bugs; the rare occasion when you can let the garage doors fly open without risk of heat loss or blood loss. Now need to get the covering done so can begin painting before the snow flys!