I've been asked several times about modifying a Fly Baby to not need the external bracing wires. So, what about it?
Well, one way to answer is to look at the Warner Spacewalker/Revolution/Sportster, or whatever name it has, now. It's basically a Fly Baby with a cantilever wing.
Here's a photo of a Spacewalker wing under construction. The aft spar looks like a 3/4" - 1" spruce plank, like the Fly Baby, but the front spar is a thick, high, wooden block. Looks to be about 6-7 inches tall, and ~3.5 inches wide. I actually think this is a box spar, not solid, but obviously it would need to be built up (and built straight!). That wing is at least 8" deep, compared to ~6" for the Fly Baby.
The top of the Fly Baby spars are beveled to match the slope of the nose ribs, center ribs, and trailing edge ribs. Be hard to bevel/curve the top of that box spar, so you'd probably end up using big one-piece ribs like the Spacewalker.
The other factor is, what does that been ol' beefy spar bolt onto? Not a stock Fly Baby center section, of course, since the two bulkheads are only ~3/4" wide to match the stock spars. So you'd have to beef up Bulkheads 3 and 5 to make them just as wide as the box wing spars, AND move the opening higher to that the lower part of the bulkhead matches the height of the wing. This opening is what your legs stick through when you fly, so it'll make the cockpit a bit more awkward.
Ron Wanttaja
