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Amsterdam - 14, 15, 16 November 2002

Fluidic design

by Axel Thallemer

Hello. Let’s think about fluids . . .

The first materials we used to design with were stone, and natural composites like wood. After adding fire to ores, we produced metals. Later, we added ceramics and glass – the fourth category of construction material. The fifth type of building material is membrane. In earlier times, membranes were pelts, fur, leather, and woven textiles; currently, we are developing technical textiles.

Now for the sixth building material, to which computing opens the door: fluids.
The Fluidic Muscle is a hose consisting of alternate layers of elastomer and fibres and can be operated as an actuator with compressible as well as non-compressible fluids. Unlike a traditional drive, this actuator has no piston or sealing ring – no moveable parts. The Fluidic Muscle can be used in tensegrity structures or in dynamic, flexible applications.

Fluids, used with construction membranes, are capable of causing an industrial revolution.

Look at dragonflies. The wings consist of a Y-shaped structure, and this three-point knot was the inspiration source for the exoskeleton used for our Airtecture at Festo with its Y-shaped supporting columns. Air is a fluid, a compressible one like all the gasses, while water is a non-compressible fluid, and you can make use of both, as we do.

Our Airtecture buildings are self-regulating, self-organising, and always changing, depending on the load. Even the ropes and cables can be altered so that they contract, and then you have a fluid actuator. They can be semi-transparent, they can be arrayed in a way so as to give stiffness and structure, and intermediate membranes make for tolerance, because such a building or structure will change according to the ambient conditions of sun, wind, and rain or snow.

The interior is spanned by a fluidic roof, where you have either pressure or non-pressure, in this case a vacuum, to make an undulation, which stiffens the roof. The windows themselves consist of four membranes, and these make up for all the longitudinal changes.

You can make inflatable manned aircraft, which can take off from the runway without the gears rolling on the tarmac. You can have inflatable wings, you can have very easy-to-fly ultra-light aircraft where the trailing edge changes according to the movements, left, right, up and down. Or you can have unmanned delta wings, which are capable of flight.

When you look at leeches, you see two angles under which the muscle fibres meet in a spiral form, and to transfer that, you get to an actuator. They can be miniaturised so that you end up with prosthetic devices, which we may one day use in minimally invasive surgery, or in very, very small components.

Inflatables and membranes are even an influence on the graphic design that we are using at Festo, since our pictograms, even the design language, change to reflect pneumatic elements.

Our Cocoon emergency tent is derived from insect cocoons. It offers the possibility of survival for 24 to 48 hours and weighs only 100 grams. And the mermaid’s purse, or shark’s egg pouch, gave us the inspiration for the office sleeping pillow, which prevents keyboard imprints on the forehead!

Airquarium is a truly mobile architecture using a very special membrane. The membrane changes translucency according to the ambient light level. So when there is no sun, it is translucent, and when there is a lot of sun it’s getting whiter, more opaque.
It has a membrane torus, which is filled with 120 –150 metric tons of water depending on the slope, which acts as a foundation. Over this spans a half-dome of 32 metres diameter and a height of 8 metres, supported by air pressure. And the idea came from raindrops, which naturally form a spherical shape when they land on a water surface.

Airquarium can be deflated and used again; it goes into a 20-foot container, and a second 20-foot container houses all the technical equipment needed to get it up. So you have a portable architecture using fluids, water and air, and the membrane itself behaves in a very intelligent way, as it changes according to the ambient light.

Festo’s Airfish is an airship based on the form of penguins’ bodies. When you study penguins, you find that their drag co-efficient is much better than any sports car. When you apply the same aerodynamics to hulls and surface bodies, they have such an amount of freedom in movement they can perform aerobatics. And with six degrees of freedom in movement, they can be very agile with very little energy.

Air on Aqua is an inflatable sports field which floats near the coast, for all kinds of beach sports like volleyball. The players are not hampering the sunbathers, and vice versa. It was inspired by water lilies.

This inflatable mobile theatre has ‘muscles’ which allow it to fit into different city spaces.

Airhopper is a shoe, which allows you to jump much faster than you can walk.
It is based on kangaroo sinews and it stores the kinetic energy which otherwise would be lost when you’re putting your foot down onto earth again, so you can get a bit back from gravity.

Aircruiser, a re-innovated skateboard, works in such a way that you have the suspension, the dampening and the steering intelligently built into the muscle material, just like with this insect. You have a very high clearance, and you can just steer by moving more or less over to different sides of the board.

Airbug is a six-legged walking beetle, an autonomous walking machine dedicated to landmine detection and clearing. It is very low in metals, and very high in composites. It is driven by artificial muscles.

This flat six-muscle engine is for our Airkart, fluidically powered. We are currently working on high-temperature versions, not to burn fossil fuels, which we never do at Festo, but for a chemical reaction where a lot of gas results instantaneously from a drop of fluid and then powers the muscle itself.

Our modular 36-muscle engine allows you to fluidically power energy sources. It allows you to add power in a very discrete way. Normally you cannot change the number of pistons in an engine, but with this system, you just add more and more muscles until you have reached the number of 36.

This is a fully sprung mountain bike, made with the help of intelligent membrane material. The diamond-shaped frame has been calculated so that a maximum of the muscle’s capability is being used in dampening and springing.

When you think of jellyfish, you come to balloons. This is our inflatable balloon basket – the first innovation in wicker basket ballooning since September 1783, the inaugural flight of the Montgolfier brothers!

We do a lot with the membranes in order to build with fluids; you have to design the borders, meaning materials R&D. There is no metal inside. With all the structures, you see a similarity to jellyfish, because they are filled with water in water. The same applies here, you have the same fluid inside and outside. The only difference is gravity of course, and temperature as well as the energy level changes.

And that brings us to another way of buoyancy, an aesthetic one, when you have fluids that are lighter than the surrounding fluid. And then you get lift, and you can of course use the same fluid with more energy in order to create a larger object. This is the largest inflatable airship for hot air use. You use a cold fill first, then you compress the fins with hot air, and then you can lift off. You don’t need an airport, and you steer with the help of fluids that change the angle of the membranes of the fins. So left, right, up, and down are all done by temperature changes.

The flat bed truck that transports the airship weighs in at only 7.4 tons, so it’s not a huge truck, although some 22 metres long. And you just let the hot air out of the membrane, and then you can fold it up, and just drive somewhere else. Now, when you do the very same with a traditional airship, you lose some 100,000 Euros worth of helium. Not so with the hot air version. It costs you only 300 Euros to heat up the air. Another advantage is flexible flying, because you are very lightweight, and the only metal pieces are parts of the engine and the cabin.

You can apply the same principle to a technology centre and cover it with fluidically structured roofing, and cover the fronts with membranes, like sails. On top, you see the air-covered roof which contains certain layers that are all printed in a checkered way. And by changing the internal pressure, you have a continuously variable sunshade. On the right image you see that one is open, while the other is closed. The whole office is wirelessly connected, including keyboards and mice, for some 1500 people.

Here is another Festo world record, the world’s largest single stem umbrella, called Funnbrella inspired by the chanterelle mushroom. It has an edge length of 31.6 by 31.6 metres covering 1,000 square metres, and this very record will hopefully last for another ten years, so that we can further improve our span by the help of new materials.

All of this work was made possible only by the heavy use of computational simulation, as well as fluids.


John: I’m just getting ready for the panel. Here’s a remarkable body of experimentation. How many years of work are we looking at in that presentation?

Axel: Eight years now.

John: And we’ve heard about biomimicry and about materials innovation, does one depend on the other? Is it now possible to copy a scarab beetle or a membrane in ways that could not have been possible 10 years ago?

Axel: Definitely. It has something to do with the mathematical methods on the one hand, and newly developed materials on the other one. But there is no direct copying. You can only gain inspiration from nature, and find what is useable in that and what could then be translated into a different system.

John: And when you look at, for example the way the fluids are transported from one place to another in the airship - is that just a mental innovation or do you require technical support to do that?

Axel: A lot, of course. We started working with chemical firms in order to have new fibres, new coatings, and new jointing techniques, and in the end also new control techniques with the help of newly developed sensors in order to make everything controllable.

: And do you find that people from traditional aircraft design understand what you’re doing?

Axel: No, they find it totally crazy.

John: Is that pleasing to you? What can you learn from those guys who’ve been doing it for so long?

Axel: The problem is that in most cases there’s very little interaction, because they think it’s ridiculous. I cannot understand how they can be so conservative, because if they had always been that conservative, there would have been no flight.

John: Here comes the table . . .

Here's an interesting interview with Axel Thallemer published in the "New Scientist":

Castles of air?
Are we ready to live like modern nomads, with ultra-advanced homes that pack up and travel with us wherever we go? For towns that spring up and vanish when they are no longer needed, or spacecraft that could be any shape you wanted. Axel Thallemer certainly is. His big idea is to build real inflatable buildings that are as far removed from the blow-up jokey plastic world of the 1960s as you can imagine. And at Festo, where he is head of corporate design, they already have eight years of experience in building working prototypes that are among the most advanced in the world - and the only ones based on close observation of nature. Liz Else caught up with Thallemer at Festo's headquarters


updated Monday 31 March 2003
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