Mark Van Noy asks about finishing the Nymph.

I've read your finishing section and have gotten the impression that painting the composite wings of my Nymph is a bad way to go since it's challenging to het the paint to stick and it apparently could attack the foam. The only other way I can think of is to use Monokote, but I have read that the heat from the iron can weaken the resin bond. Is there a good safe way to cover the wing? I noticed your yellow Nymph at the back of an S&E modeler issue so I know there has to be some safe way to do this, but I am not sure waht that way may be.

From : Don Stackhouse

First, for the record: We DO NOT recommend painting the Nymph at all, other than perhaps fogging just a little black paint (such as Krylon spray paint, fogged on from far away enough that the solvent flashes off before the spray hits the wing surface, so the solvent doesn't attack the foam) onto the underside of the wings to make it easier to see at altitude. The reason is weight. The smaller the model is, the more sensitive it is to weight, and Mosquito class models like the Nymph are among the most sensitive of all. Remember, induced drag is proportional to the square of the wingspan, so the weight of a Mosquito class (.75 meter) model compares to a 1.5 meter RCHLG that weighs FOUR TIMES as much. By that criterion, a 3 ounce Mosquito is like a 12 ounce 1.5 meter model, 4 ounces is like 16 ounces, and 5 ounces is like 20 ounces! Obviously, everything, including appearance, must take a back seat to weight if you expect it to fly well.

That concern about weight starts here in manufacturing, where we don't gel coat the fuselage (looks pretty, but adds unnecessary weight) and use a lightweight slurry for joining the fuselage halves, that despite being thicker than a taped seam is actually lighter because of the material's lower density (it's also a necessity because much of the Nymph's fuselage pod isn't accessible for rolling a taped seam after the mold halves are joined; the weight reduction from the slurry is a nice plus). You need to do everything you can as well to minimize weight when you assemble the model. Don't obsess about finish, use lightweight radio gear that can also tolerate running on 50 mah 3-cell batteries (such as the Hitec 555 or Berg-6 receivers and Hitec HS-50 servos), and avoid using excess amounts of glue when assembling the tail.

You must decide right at the beginning whether you want your model to have a gorgeous "Toledo Show" finish that makes it good at nothing other than sitting on a shelf, or an absolute minimum of finish in order to keep the weight down. Trust me, at 50 feet altitude, you will not notice any details of the finish. OTOH, if you put a spectacular finish on it, you will have lots of opportunity to see it up close, because it will take the Mother of ALL Thermals to get a decent flight out of it (note: those of you fortunate enough to live in So.Cal. and other places gifted with a steady supply of such thermals can probably get away with ignoring this).

So, you live near L.A. or Texas and your thermals are known to regularly carry off children and small automobiles, and you want a "Toledo" finish on your Nymph anyway. What do you do?

First of all, put away the Monokote iron. The Nymph you have is a "Glass Nymph", and the one you saw in the photo was a prototype of the "Wood Nymph". The Wood Nymph uses built-up wood construction, and is covered with Monokote in the usual fashion. This one isn't quite ready for production yet, we're still refining the wing structure to improve the flutter resistance for launch. If you try to cover your Glass Nymph with Monokote or other iron-on film, you WILL destroy the wings!

For a painted finish, you'll need to fill the glass to eliminate pinholes. Some folks use rubbing compound with good results, but a lightweight finish like "Model Magic" or lightweight spackling compound is usually a better choice. Thin it a tiny bit with water to make it easy to spread, then smear it all over the wings. Let it dry thoroughly, then sand it all off. Be careful, it's easy to put dents in the wings from handling, or to sand through the thin skin. When you're done there should only be filler in the pinholes and low spots.

For paint we recommend one of the water-washable acrylics, such as the paints Tamiya sells for painting Lexan R/C car bodies. They're available in a wide range of spectacular colors, and use an alcohol-based solvent that does not attack styrofoam. You can also use these paints to tint Varathane for the final coats in applying Varathane finishes to wood, such as the bright yellow and red finishes on the fuselages and tails of some of the Chrysalis HLG and 2-meter photos shown elsewhere on this website. Just apply the first two VERY LIGHT coats of clear Varathane (or other equivalent water-based urethane varnish) to seal the wood, let dry very thoroughly, then apply two more coats of tinted varnish. Properly done it looks good and doesn't add much weight. Of course, like I said, for a Mosquito class model even this much added weight is still too much.

Now sit back and admire you beautiful (but portly) "Leaden Nymph"! Oh, well, maybe with a slope and a fairly strong wind...

Don Stackhouse
DJ Aerotech