DaveGadgeteer
Member
Imagine a small (2-3 inches) device shaped something like a light-weight house-door hinge, with little friction, supported by the (vertical) hinge pin and held open to a 90 degree angle by a very light spring.
I'd like to have it blow closed (0 degree angle) when there's a wind greater than say 20mph, and open when it's standing nearly still.
The idea is to have maximum visible area from all directions when it's standing still, but minimum wind resistance (folded flat, closed) when it's moving.
It seems to me this will be difficult, because when it goes nearly shut the air rushing by outside will suck it open (Bernoulli), and it's likely to oscillate between open and slamming shut, making a lot of noise and vibration.
The shape can be quite refined because it is to be 3D printed, and the structure can be very light weight (hollow fluorescent ABS plastic).
It could be operated by small model aircraft servos, of course, but it would be much more elegant if it could be passively wind operated.
I'm looking for suggestions on where to learn about such things, or suggestions on how it might be done.
E.g., perhaps trim tabs on the trailing edges could be used to keep it stably closed.
Or a structure like a nesting lid on a box, forming an air pocket, with a tube to a low pressure area, might serve to damp the oscillations and pull/hold it shut.
Or so-and-so has free software for CFD that could model such a thing.
I'd like to have it blow closed (0 degree angle) when there's a wind greater than say 20mph, and open when it's standing nearly still.
The idea is to have maximum visible area from all directions when it's standing still, but minimum wind resistance (folded flat, closed) when it's moving.
It seems to me this will be difficult, because when it goes nearly shut the air rushing by outside will suck it open (Bernoulli), and it's likely to oscillate between open and slamming shut, making a lot of noise and vibration.
The shape can be quite refined because it is to be 3D printed, and the structure can be very light weight (hollow fluorescent ABS plastic).
It could be operated by small model aircraft servos, of course, but it would be much more elegant if it could be passively wind operated.
I'm looking for suggestions on where to learn about such things, or suggestions on how it might be done.
E.g., perhaps trim tabs on the trailing edges could be used to keep it stably closed.
Or a structure like a nesting lid on a box, forming an air pocket, with a tube to a low pressure area, might serve to damp the oscillations and pull/hold it shut.
Or so-and-so has free software for CFD that could model such a thing.
