Yukihisa Isobe: Castles in the Air (1969)

By Jud Yalkut

First published in:
BIjutsu Techō, June, 1969

Art is an evolving environment.

The divergence between art and life is increasingly being negated amid the move toward the fusion of art and technology, and landscapes are metamorphosing from illusions painted on canvases into substantial embodiments of the mind.

Our experience of art has been shifting away from the moist passions of the heart toward the dry operations of the central nervous system, and has now exploded into total sensory experience. The introspective decadence so common in Romanticism has faded and been replaced by the metaphysical beauty of both introspection and extroversion, attained through understanding of natural laws.

Kinetic art is the realization of the potential energy of selected materials— whether these are pure mechanical principles, the natural rusting of an iron sculpture, the blossoming of crystalline reactions, or the release of air pressure from expanded membranes.

Aesthetic involvement is increasingly shifting toward the environment, the physical spaces around us, and the four elements of fire, earth, air, and water.

Ever since Leonardo da Vinci designed a flying machine lighter than air and inflated sheep intestines to an enormous size with a blacksmith’s bellows, the medium of air has caused the human imagination to soar to extraordinary heights.

However, we have gone beyond mere flights of fancy, and human flight has indeed become a reality. We have even achieved liftoff into the vastness of outer space, piercing the heavens like the Tower of Babel. Air infiltrates the metabolic processes of life, generating flow and movement between its poles, infinitely compressing and expanding.

Marcel Duchamp trapped air in a glass vial and titled the work 50 cc of Paris Air.

László Moholy-Nagy (1895–1946, Hungarian) endeavored to suspend a flea in mid-air by emitting compressed air. Meanwhile, Buckminster Fuller (b. 1895, American) surrounded air with a geodesic dome to achieve total environmental control.

Air exists within architectural spaces; it is both put on display by these environments and a force shaping them. So, why not build with air itself? “Air structures” have already become a reality in the form of multifarious types of inflatable constructions.

Yukihisa Isobe is a pioneering young spatial planner who is exploring the enhancement of air structures’ mobility, durability, and flexibility. Born in 1936 in Tokyo, Isobe studied painting and sculpture at Tokyo University of the Arts and then architectural design in New York. He has lived in New York since 1966, but opportunities for hands-on architectural design have been scarce, as he is not oriented toward working in an office environment.

In Isobe’s words: “I have actually dedicated myself to finding a synthesis of architecture and sculpture, and I am always focused on issues of spatial scale. When I say spatial scale, I am talking not only about size but also about intrinsic value.”

Isobe began as a painter and had several shows in Tokyo, Paris, Venice, and New York between 1962 and 1967. Notably, in an exhibition of contemporary Japanese art at The Museum of Modern Art in New York, he showed boxes that transformed reliefs of traditional Japanese crests into Western heraldic forms. 

“Issues of three-dimensional repetition still intrigue me.”

Q (Question = Yalkut): The concept of three-dimensional repetition appears to be related to Le Corbusier’s idea of the module. What led you to the idea of repeating units?

A (Answer = Isobe): It actually came to me suddenly, around 1960, as I recall. It is quite difficult to explain the reason. I have continued to use this approach, fundamentally unchanged, in both pneumatic structures and airflow projects. However, now I think I can understand why I use repeating modules. When I initially applied this to painting and sculpture, it was quite spontaneous. The concept of repeating modules is inherently present in any structure. Buckminster Fuller, too, employs the principle of modules in his work.

Q: At what point in your painting and sculpture career did your structuralist philosophy begin to develop?

A: It was a long time ago, when I was still painting. I had a particular way of thinking about scale, specifically the placement of differing scales and their transitions and combinations. This eventually led me to thinking at extremely large scales. For some of my projects, such as the 1964 wall relief and the 1966 playground (the Zenkyoren Building wall relief and the Yokohama Municipal Pool), I realized that larger scales could be more effective. The goal[MOU6] [JR7]  of the latter was to use chromatic design conditions to create play environments for children. These days, though, I’ve been adopting a somewhat different approach. I focus more on pursuing principles than on specific practical applications. I happen to be a Scorpio, and it’s almost like I’m projecting the constellation Scorpio, which is really just an abstract geometric pattern, into the sky and connecting the dots with cosmic-level imagination. In this regard, my field is abstract design, and I consider myself an abstract structuralist.

In the February 1967 issue of Progressive Architecture, Isobe wrote: “Gallery art is affected by the artist’s character and sensibilities, and can be more private, complex, and introspective. Works that involve structures, on the other hand, is more public, makes use of ready-made materials, and is designed to be used directly by people who may have no experience with gallery art. It is an extroverted art that forms part of an environment.”

Building on this concept, Isobe proposed a project called “Sculpture in the Streets” to the Architectural League of New York. The proposal included a ten-page description, models, and blueprints, and envisioned using steel and aluminum tubes to construct a space frame that appeared to float between old apartment buildings. This structure was designed to apply bright colors not only to the walls but also to the ground, and to feature small spotlights that would enable people to enjoy night views. Of course, such installations would be particularly effective in monotonous areas with little environmental variety.

Q: Let’s discuss practical applications of your ideas for structures.

A: Recently, various issues have emerged around urban planning, and by extension, around large-scale structures. As these structures grow ever larger, they inevitably face problems concerning the weight of materials. These fundamental problems require the evolution of architectural concepts, and this has led to the exploration of suspension structures, tensile structures, and shell structures, for which weight issues are significantly less critical compared to steel buildings. One example is a suspended structure with a space frame composed of joists and horizontal trusses, where a box-shaped structure is suspended by wires from a frame. Wires from the four corners of the box converge at a single point, which is then secured with wires from three joists. A horizontal boom stabilizes this point in space, using the Triodetic Way System.

[Photo caption]

Yukihisa Isobe, Floating Frame with Parachute Canopy, 1969. In 1969, at the State University of New York[MOU8]  in Oneonta, New York, a parachute canopy with a diameter of 35 feet and a weight of 15 pounds was suspended in mid-air by the force of wind blowing at 13 kilometers per hour.

Q: A suspended structure leverages the material’s resistance to gravity through tension and compression, is that right?

A: That’s right. As with most of my work, it’s an abstract idea, and it’s not easy to envision someone applying this method to a building or structure in the near future.

Q: But, maybe someday... It will take time to make it a reality.

A: I’m sure. That’s why I’m currently conceiving abstract ideas through models.

Q: Can you tell me about your “tent structure with collective compression members?”

A: The principle is extremely simple. Typically, any tent requires internal structural elements. Large poles are often used as such elements, but they take up internal space that should be used for other purposes. I conceived a tent structure without internal structural elements. Specifically, a central mast between 100 and 150 feet high suspends five surrounding tents from its top using the tension of cables. Five main cables extend from the main mast to the apex of each tent, with the tension of each cable distributed among sixteen smaller wires extending towards each tent’s anchor. This means there are eighty points of tension that support each other while converging at a single point on the main mast, from which all the tents are suspended. Any supporting tower must be robust, and requires some kind of supporting cables. Tension delivers maximum external support, keeping the interior space completely empty and freely usable.

Q: After your suspension work In the Air, in 1968 you moved on to create a work using pneumatic structures.

A: My recent work revolves around airflow. Pneumatic structures directly relate to air pressure itself. I am currently exploring new structures driven by airflow, which will likely be deeply connected with aerodynamics. Structures formed by airflow undergo a sequence of transformations, generating amorphous forms of an entirely different type.

In my pneumatic structures, I use recently developed materials, but these inevitably limit me to balloon-like forms, that is, either convex or concave forms.  There are no truly ideal materials that have reached the stage of practical use.

Even with pneumatic structures, I endeavored to create something that can function as an actual structure, utilizing the concept of pressurized tubes in car tires, but this would be more accurately described as a basically abstract idea.

I subsequently conducted a demonstration using pressurized air cylinders as compressive materials during the Experiments in Art and Technology (E.A.T.) exhibition at the Brooklyn Museum. The cylinders had surfaces inclined against the wall and were supported by the tension of the compressed air inside. I had to devise a special apparatus for this structure. With pneumatic structures like these, under normal circumstances, it is impossible to maintain the same shape for more than two months due to air leakage; particularly when they are used as compressive materials, even a slight decrease in internal pressure causes the cylinders to bend and fail as compressive elements. However, my apparatus was able to maintain constant internal pressure without relying on the continuous operation of a compressor.

Q: So, does that mean you used a device that automatically modulates the replenishment of air when the internal pressure of the cylinder drops?

A: Yes, I developed that idea for architectural purposes. It is completely economically unfeasible to use blowers or compressors to continuously fill buildings or other large structures with air.

I use a pressure gauge that automatically reacts to changes in the cylinder’s internal pressure. With the inclined cylinders, the material is subjected to pressure from both inside and outside. This is one reason why it can serve as a compressive material while standing against the wall. Structurally, it consists of an assemblage of double-membrane cylinders powered by air pressure. The internal pressure of the cylinders shifts automatically in response to environmental factors—ambient pressure, temperature, humidity—via a differential pressure gauge. This automatic control not only shapes but also supports the structure’s form. The pressure gauge responds to even slight changes in the cylinder, like air leaks or changes in external temperature, by switching on the motor and applying pressure until an appropriate internal pressure level is reached. The switch automatically turns off when a certain internal pressure level is achieved, and this level can be preset on the differential pressure gauge. The simplest pneumatic structures were mostly balloon-like and had no load issues when used as compressive materials. However, the material was not strong enough to completely seal in gas.

Q: What types of materials do you use, and how have you dealt with the issue you just described?

A: I use ordinary vinyl or plastic with a surface finish, ranging from 8-gauge to 10-gauge. The colors are largely white and black. In structural experiments, color takes on a different kind of importance than in artworks: white reflects sunlight the most, while black absorbs it the most, and I chose these two colors due to the need to study reactions to changes in external air temperature. With materials that cannot completely seal gas, the only solution is to supply constant internal pressure with minimal power. It’s necessary to use thin, flexible materials with high air permeability. Sometimes, with membrane structures and the like, it is extremely difficult to prevent gas leaks. That’s why airflow structures are more versatile than sealed structures.

For one thing, they do not require an airtight room. Also, they can easily cover large spaces, which is surely compatible with architectural utility. I am currently interested in floating compositions using parachute canopies. The canopies themselves are very beautiful colors. The idea is to open the canopy with a blower and stabilize it in the air. It will no doubt need to accommodate complex conditions related to aerodynamics. Using a single piece of nylon fabric is a possibility. The four corners of the fabric would be tied to strings suspended from the ceiling, with weights placed about ten inches from these knots to fix it in space. The nylon fabric forms a concave surface, which becomes convex when air is blown from below. 

[photo caption]

Yukihisa Isobe, Air Flow Structure, 1968. This structure supported by air flow was designed as a model for a section of the Tokyo Metropolitan Art Museum. It is to be constructed from canvas or vinyl fabric and anchored in space by wind pressure.

[photo caption]

Yukihisa Isobe, Tent Model with Parachute Canopy Shape, 1969. The lines of the canopy are secured to ground anchors, and natural wind force is harnessed to stabilize it in space. Calculations have also been made to withstand windless conditions.

[photo caption]

Yukihisa Isobe, Air Flow Parachute Screen, designed for Jud Yalkut’s performance Dream Reel[MOU9] [RV10] . Six projectors display slides and project 16mm films.

Q: The relationship between the mass of the weights and the amount of wind, as well as the fabric’s air permeability, weight, the quality of the wind, and its direction, would all result in different outcomes, right?

A: Yes, that’s right. Airflow structures have greater potential than sealed structures. They can also be viewed as sculptures, which do not require any specific location. We can think of them as based on the extremely simple condition of wind blowing. Indoors, the canopy would be suspended, but outdoors, it would float on its own. The only issue is the capacity of the blower.

Q: Even outdoors, it would be fixed with cables, right?

A: Of course, it would need to be secured from below in some way.

Q: Indoors it would be hanging down, but outdoors it would need to be hanging up. Can a blower actually push the canopy up?

A: It is certainly possible, especially outdoors, where hot air can be utilized. It is well known that warm air currents have lifting power. Indoors, achieving lift would be challenging due to the inability to regulate temperature. This principle is akin to that used in the Montgolfier brothers’ hot air balloon. It might also be possible to employ electromagnetism for this kind of canopy suspension. A canopy made of lightweight materials, detached from the main structure, could be supported above the main structure by the repulsive action of electromagnetism. If electromagnetic control is possible, the canopy could be completely stabilized. However, in a building, the magnetic force would need to be shielded by insulators to protect people going in and out.

Another approach involves supporting the apex of a tent with an air turbine powered by a jet engine. The turbine’s air jets generate enough lift to support both the turbine’s own weight and the tent’s structure. Aerodynamics experts say that certain types of powerful air turbines can sustain weight in midair, much like a helicopter.

Research on sails, including triangular sails in air flow structures, exclusively focuses on wind power. Actually, though, aerodynamic effects can be expected to produce various kinds of conditions. This results in designs in which all forms are streamlined. At the same time, deformations caused by the wind going still can be prevented with basic support frameworks. In any case, air flow structures have powerful aesthetic appeal and great sculptural potential.

Q: By emphasizing functionality, they also achieve beauty in their own right.

A: Absolutely, I think so. My approaches not only produce aesthetically appealing results as sculptures, but also apply structural concepts.

(from a Japanese translation by Shigeko Kubota)

Air Flow Parachute Screen (also pictured on the right-hand page) lit by projections and lights from projectors. The parachute, spanning thirty-two feet, was displayed in Oneonta, New York, on March 23, 1969.

Jud Yalkut's writing on Yukihisa Isobe, written for the Japanese journal Bijutsu Techō in English, translated into Japanese in 1969. As we could not locate the original manuscript in English, we have translated back into English in 2024 with permission of the Jud Yalkut estate. Translated by Colin Smith.