Sunday, September 13, 2009
Flying a better Mousetrap
I've been flying monocopters since 1988. I've also seen
other people fly them. They all shared two common
problems, the first is getting them to stay in one piece
throughout the flight despite the high rotational loads.
I've seen a few fly apart, including some of my own.
Anyone who hangs in there a while, can conquer this
sooner or later.
The second problem is the subject of this post. When
a monocopter's motor shuts off, they typically stop
spinning and fall down. Some falling monocopters will
reaquire spin, either backward or upside down, hopefully
before impact,and make a safe landing.
In short, after getting monocopters to go up reliably, the
next trick is to get them to come back back down safely.
I've seen other recovery methods tried with varied success,
but the coolest will always be autorotation, ie; true
mapleseed recovery. Spinning up, and spinning back down,
without stopping, without falling.
Last fall, I built the 1st step on this quest. I call, it the Flying
Mousetrap. It somewhat looks the part. Mousetrap has a
wing that pivots around the center of lift. There's a spring that
pulls the wing to descent angle, and a length of string to hold
the wing at ascent angle until the motor [D12-3] ejection burns
it through. This gives a timely transition after slowing to
autorotaion speed, but without falling or reversal. The string is
actually dental floss, it's easy to work with at the field, and it
comes in a neat dispenser WITH a built-in cutter.
Minty fresh too.
I don't consider this to be the best approach to the problem.
It's a simple up/down system instead of being reactive, and it
limits the choice of usable motors to ones with suitable delay
and an ejection charge. Since I make my own sugar motors,
I would prefer a system that can use them, and they're all
capped. However, I figured this would be a good first step
that others might prefer.
The 1st flight video was posted by friend John Lee at the time.