 Time
for a diagram, it usually helps clear up the problem. So, I'm trying to
move a wing from straight down to straight up using a pushrod. Look at
the geometry. Move the pushrod up by one unit, the wing turns by forty
five degrees. To turn the wing by the remaining forty five degrees only
.41 units of vertical movement. (Its a root two thing) The higher the wing
is raised the less the vertical component of the movement, The higher the
pushrod, the less the force applied to the wing so the harder it becomes
to raise the wing. Somewhere before vertical the force on the pushrod is
not enough to overcome the stiffness of the paper joints and the wing stops
moving. Realistically on this type of movement I can only rely on ninety
to one hundred degrees of motion. What if I want more? What can I do? I
can't think of a simple solution. Rack and pinion gears seem to be the
obvious solution but tricky to make out of card, Especially when compared
to a pushrod. I think I need to go for a bike ride, I do all my best thinking
whilst pedaling :-) |
Pushrods,
central to many mechanisms. I'm working on a new design (more of which
at a later date) that requires a wing to be moved, right up then right
down again. Much further that the Flying Pig, left. Ideally I'd like 180
degrees of movement. The problem is it just doesn't work using a pushrod.
Let me explain...