Thursday, February 25, 2010

That Sprue Thing One More Time

It Never Ends

Well, that's true to a point, but you've gotta cut me a little slack, age being what it is. It's not that I forget things, although I do, but more a case of forgetting all the stuff I meant to say at the time I should've said it. Add that to the notion of scope (We're talking about rigging a biplane so that's all we're going to do!) plus a fair dose of innate laziness and you probably get the picture and, therefore, gain a fair amount of understanding as to why we didn't discuss antenna wire (actually, that wire is the antenna on real airplanes that have it) back when we were stretching sprue. We shoulda but we didn't, so now we will.

There won't be any sprue stretching today, though. We already talked about how to do that, and once is enough. We won't be talking about the rigging of anything with more than one wing, either, because we already talked about that. Today's treatise is really simple; we're going to talk about how to do antennae with sprue. We're going to use the same white glue and the exact same technique, but we're going to add one tiny little trick to the mix. We're going to talk about how to make complex antennae with more than one wire, but it's not going to be much of a discussion because it's so darned easy to do!

First, you need to put your primary antenna (wire) in place. I prefer to put a precut end on the antenna mast with white glue, lay the other end over the mast or attachment point on the tail and glue it in place, then trim the excess off the tail mast once everything is dry. Sometimes there isn't a mast on the tail so, at the risk of being extraordinarily obvious, we'll just reverse the order and mount the antenna to the tail first, thus putting the excess on the mast up by the cockpit. We're still going to trim after it's dry, at which point we'll notice there's probably a little sag to it.

If that sagging antenna is of the single-wire variety (with no other wires running to it) then we're basically done and just need to tighten it up a bit with our trusty soldering iron, once again taking pains to only apply the heat source to the stretched sprue rather than to the model. That would be Common Sense 101, but the reminder never hurts.

Now then, what if you have a couple of extra antennae running from the fuselage or wings into the main one? No sweat, GI; just cut a piece of your trusty stretched sprue to the length you need and attach it to the proper places on the airframe and existing primary antenna wire before you tighten anything up with your heat source. You'll need to make sure you've got the right length the first time around but that's no big deal and, if you mess up, all you have to do is remove the offending wire and start over. Practice a while and you'll get it right the first try most of the time. Once you've added the extra "wire" and the white glue's had a chance to dry, you can apply your heat source like you normally would. The shorter piece of sprue generally won't tighten up, but the longer one will, thus adding the correct tension, and therefore appearance, to the antenna.

So, what if the airplane you're modeling has a taught primary antenna and a little sag to the secondary? That's easy too; just tighten up the primary antenna, then attach the secondary and don't use heat there. Too easy!

You'll need to detail the ends of the antennae too, but that's as easy as the rest of the procedure. A lot of WW2-era airplanes used ceramic insulators where the antenna mounted to the airframe, and a spot of white glue in the appropriate place will work wonders. Tensioning springs are a different matter; some antennae had them, but they're almost too small to be added as actual springs until you get into the 1/32nd and larger realm of things. In that instance, take some .006 diameter brass wire, heat it quickly over a low-intensity flame to anneal it, then wrap it around a .010 dia wire. Cut it to length and slide it over your antenna wire before you attach it to the airframe, and secure with white glue once everything's dry. Standoffs (those little posts that sometimes stick out from the fuselage or wings to allow attachment of the antenna) can be easily replicated by appropriate diameter wire; just drill the proper-sized hole, install the standoff with a tiny spot of cyanoacrylate, and add your antenna.

Today's photos are of a couple of models that have the sort of antenna arrangements we've discussed. You may have to look closely to see everything because I try to get
scale thickness on my antennae, but they're there and they'll show what I mean far better than I can describe it. The A6M2-N (Rufe) only had a single antenna and the model of same is included so you can see just how much difference those other wires make. This is another Old Dog Trick that's still useful, and it makes a nice addition to your library of techniques.

See you later,

No comments:

Post a Comment