An umbrella incorporating patches of one-way-permeable material. The umbrella remains waterproof, but air (and water) can pass through from beneath, preventing the umbrella from being shredded or pulling its holder off balance.

(The material I have in mind is a stronger variety of the porous plastic wrap that bread sometimes comes in.)
-- Monkfish, Jan 15 2003

rain shield http://www.halfbake.../idea/rain_20shield
[Monkfish, Oct 04 2004]

Nah, it'd cheer her up. (Nannying the von Trapps, that it.)

Besides, I don't think your idea is workable.
-- DrCurry, Jan 15 2003


[Jutta], I've seen these too; and I'd been meaning to buy one for years but couldn't find them. Thanks for the link!

BTW, I've invented (built) an umbrella rib splint to fix broken conventional umbrellas. It's a 2" piece of spring steel wire (I forget the guage) stamped and pierced at both ends to accept fishing line which binds the splint to the rib. The rib is straightened by hand, the kink repaired with needle-nosed pliers and the splint is bound with the line. As I don't have the skill to tie-off the line, it's epoxyed to the rib for a permenant repair.

[Monkfish], I think the idea is workable. The low inertia and small aperture of individual micro-flaps would result in lightening fast open:closed transitions unachievable with the large flaps of conventional mechanical airflow valves.

The weaving would be a real challenge, but the product would be a potential goldmine. It would have many further applications aside from umbrellas. In fact, wherever a rapid transition valve is needed for large volumes of air, your idea would be one of the best solutions. Applications include ventilation, aviation, windpower, sailing, tents and clothing, etc.

I can see two obvious structures and manufacturing techniques. Both require multi-layering (as does [Jutta]'s unbrella link):

(1) For flexible applictaions - Laser-cut synthetic zero-porosity fabric, not unlike the material used in parachutes and paragligers, but with a custom rip-stop pattern which would be tighter and possibly hexagonal, rather than square. A laser would cut valve flaps in the upper material layer and matching pores in the lower material layer. The layers would then be precisely matched and laser-bonded.

(2) For structural applications - Bird feathers are good at tailoring airflow in this way. My idea works thus: You have a hollow (actually grooved, because it's easier to manufacture) rib like the central shaft of a bird's feather; this divides into vanes that can trap air. By varying the shape and thickness of the vanes, you can control how contra-airflow distorts individual and collective vane groups. The angle that the vanes bond to the shaft also affects airflow in a different way depending on the direction through the 'feather'. 'Feathers' can be stitched/adhered to a frame. 'Feathers' behave on a macro-scale like vanes at a micro-scale, in conditions of very high wind flow.

I believe both concepts can be build with current manufacturing technology. The first is cheaper, more practical and easier to maintain. The second is more interesting.

Any other ideas?

[Moderators], I feel [Monkfish]'s idea is not baked in the way (s)he proposed and has it has great potential. Let's not MFD it, please.
-- FloridaManatee, Jan 15 2003



random, halfbakery