On Mon, 12 Jan 2009 07:21:23 -0800, Ron Wanttaja
wrote:


On Mon, 12 Jan 2009 03:57:11 -0800 (PST), wrote:

Thanks for the info. I incorrectly assumed the dual wires was for
safety. I know the Pitts S-1 and Christen Eagles have dual wires, but
only at the main spar and I though I read somewhere that they had to
be dual for safety. Obviously these planes can alter their incidence
by adjustments at the outboard wing struts. They must have a
different pressure distribution to keep them from twisting?

When you have a biplane, you've got a lot more choices....those box
structures are pretty strong, just on their own. I fiddle around with
very lightweight RC aircraft, built from 3 mm Depron foam. A single
sheet of the foam isn't strong enough for a wing (unless the plane
weighs only 30 grams or so). But a biplane setup (with 1/32" plywood
cabane and interplane struts) is good for five times the weight, even
without adding bracing.

Stealth Pilot wrote:
dual wires will *never* be for funk safety.
if one of the wires were to break the transference of load to the
other wire (immediately doubling its stress) would likely cause a
catastrophic failure. far better to have one adequately sized wire.

The Fly Baby has dual bracing wires (e.g., two to the forward spar, two
to the aft) for lower-cost construction. It's important to keep about
the same tension on both wires in the pair. There was a fatal accident
a few years back where the it's suspected someone failed to do that.

Ron Wanttaja

many lessons were learnt after the flybaby was designed.

aviation is fascinating in that if you know the age of the aircraft it
often represents a museum of the aeronautical knowledge at the time.

you may need to see a P3C orion sitting beside a B1 bomber to fully
appreciate it though :-)

Stealth Pilot