and Compressed-Air Power Notes
Compressed air has been a major topic in the past on this list. The key
advantage of pneumatic power is the cheapness and power density
(weight-to-power) of the end-use actuator, compared to an
electro-mechanical servo. Its true that compressors and hoses are usually
built heavy, with no intention to fly them. Clearly the same logic of
ground-gen v. flygen generally applies to compressed air whereby it
usually makes more sense to keep the heavy compressor and hoses on the
ground. Its quite obvious a kite can pump a ground-based compressor, with
far less weight and drag to carry aloft. KiteLab Ilwaco converted a small
automotive tire inflator for an AWECS, with an exercise bike as the
transmission. These small compressors are very common, but of rather heavy
pot-metal construction, for heat dissipation, so they are not suited to
Heat-of-compression is a valuable direct resource, not just "waste". The
skilled designer knows how to use a negative to advantage
opportunistically, and the highest art can even multiply two negatives
into a huge positive. For example, imagine a kite-powered compressor that
uses it heat of compression to liquefy tar-sand oil into plastic-feedstock
(precursor) that in turn becomes kites to offset petro-use elsewhere. The
compressed air output can drive the mechanical needs of the kite actuation
and material handling.
This forum has extensively discussed the storage of compressed air in bags
deep underwater and many other interesting compressed air variations. A
nice lightweight pressure vessel can be made out of a soda bottle with
S-glass strapping-tape girding, suited for up to about 250 psi. Light
weight compressors for flight use can be cobbled from the tire-pumps
carried on bikes. Bicycle collectives usually have a bucket-full-or-so of
old road bike pumps, but newer short-stroke versions are cheap and some
even have double action.
Low psi air has many AWE uses, and today's LEI and ram-air kites are just
a beginning to active morphing soft kites that become giant robots in the
sky. Those automotive sensors are just one of many COTS components to
apply, with endless new designs for active structures possible. Conical
fabric valves and air-bag "muscles" are a basis for magascale actuators.
~Dave Santos 20Nov2011
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