Spurgin_serrano-piche_3501fall2008_web

P neumatics

CONTRIBUTORS Leo Spurgin & Chelsea Serrano-Piche

STUDIO 703

ARCHITECTURAL DESIGN STUDIO 4 COLLEGE OF ARCHITECTURE TEXAS TECH UNIVERSITY - FALL 2008

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1.0

Research

1.1

Pneumatics 1.2

Tensairity 1.3

Tensairity Con.

Pontiac Silverdome

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1.1

Pneumatics

“Structural Air”

Of or pertaining to air, gases, or wind.

Some commonly used fabrics used in pneumatic membranes are polyvinyl chloride coated (PVC) polyester fibres, Polytetrafluoroethylene (PTFE or Teflon) coated fiber glass, or silicon coated fiber glass. These membranes are translucent but by no means transparent. On the other hand, Ethylene tetrafluoroethylene (ETFE or Tefzel) foils, nowadays commonly used as air cushions for facades and roofs in architecture, have a very high transparency. Air, as a structural element, has many uses both architectural and otherwise. Pascal’s Law is what makes pneumatic structures possible. It states that air is considered the fluid which, when put under pressure in a confined area, will instantly apply equal pressure at all points of contact. As air is pressurized within pneumatic architecture, the membrane equally expands. The two basic types of air supported structures are high profile and low profile designs, which refer to the height relative to the span. Low profile designs are used to span large distances while high profile designs incorporate air in more than just the roof structure. The type of air used in low profile designs is just that, air. It is moved with fans and air ducts from the outside and circulated continuously. The same goes for high profile designs although compressors work much harder to bring the air in and keep the pressure equalized. In low profile pneumatic structures, cables are often installed to hold down the membrane when it is under pressure, rather than support it. The cables are typically made of steel because of cost, availability, and life span. A compression ring is needed to hold down and stabilize these cables in pneumatic systems used as roofs often spanning sports arenas. Using gases instead of air would be costly and inefficient. Helium, for example, would not be ideal for these membranes because their molecules are smaller than those of common air making slow “leaks” constant.

Pros of Pneumatic Systems: - Membrane can be translucent, transparent, solid for shading purposes, UV resistant, non-flammable - Membrane can have acoustic to optimize interior space - Membranes are foldable, recyclable, temporary, prefabricated, cost efficient, resistant to extreme temperatures, and fairly sturdy.

Cons of Pneumatic Systems: - Unintentional deflating and cost for this kind of repair is one of the few risks or problems with this sort of structure. Geometric shapes are preferred for pneumatic roofs. Below are some common shapes. Cable patterns are visible as well.

1.2

Tensairity

Tension+Air+Integrity Designer: Mauro Pedretti Fabricator: Airlight

The structural technique of Tensairity was developed by a Swiss engineer named Mauro Pedretti and is used to create large-span beams that minimize strut material by using low pressure air to prevent compression elements from buckling. A Tensairity beam consists of a cylindrical membrane filled with pressurized air, a compression element tightly connected to the air beam, and two cables running in a helical form around this air beam. Tension and compression are physically separated into cables and struts causing the struts to appear as free floating. Under load, the tension in the cables increases. This force is transferred to the compression element which becomes prone to buckling. However, due to the firm connection of the compression element with the air beam membrane, buckling is prevented. As in the theory of beams on elastic foundation, the compression element is stabilized against buckling by the compressed air. Therefore, the compression element can be loaded to the material yield limit. The major property of Tensairity is that the air pressure is solely given by the external load and is independent of the span and slenderness of the beam. The load bearing capacity of Tensairity is, by orders of magnitudes higher than for the traditional air beam.

Flying Roof - Bellinzona, Switzerland

A test with done with an automobile supported by two identical parallel tensairity beams each with a diameter of 50cm. This bridge was able to support 3.5 tons of weight without buckling. Each beam weighs only 88 pounds whereas a steel beam designed to support a similar load weighs upwards of 800 pounds. A normal air beam can only be pressurized to 15 bar whereas a Tensairity beam can be pressurized to 400mbar (1000 times more pressure) because of its other elements.

Above is a net based on helical cables wrapped around an transparent inflated membrane. Such a net works like a scissor mechanism. The air pressure squeezes the foil due to the elasticity into the meshes of the net reducing the curvature of the foil and thus the tension considerably compared to a structure without a cable net. For a cylinder, it can adapt forms between a very thin and long tube to a very short and thick tube.

Lanselevillard, France Skier Bridge

-Charpente Concept

Leamouth Footbridge London, UK

1.3

Tensairity

Tension+Air+Integrity Designer: Mauro Pedretti Fabricator: Airlight

Tensairity beam technology can be incorporated into a design in other ways other than just straight horizontal beams. Tensairity trusses can be implemented permanently such as with the Lanselevillard Skier bridge in France. The bridge connects two small ski resort towns in the mountains of France. In addition to supporting the dead load of the wooden bridge itself, the Tensairity truss supports the live load of snow and any skiers crossing the bridge during the main vacation seasons.

Steel Equivalents

Tensairity Shapes

- heavy weight - heavy loads - expensive transport costs - setup requires many tools - permanent - strong

- light weight - heavy loads - low pressure - small transport volume - fast setup

- lighting -adaptable -temporary

There are various footbridges that have been built or proposed that take advantage of this Tensairity technology. The Tensairity element keeps the bridge from buckling in the center which allows the bridge to only need structural elements under the ends of the bridge. The cables in these bridges are just to hold the bridge and the Tensairity element together tightly. Sécheron-Nations Footbridge Geneva, Switzerland

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2.0

Precedents

2.1

Metrodome 2.2

TTU Practice Field 2.3

Tubaloon 2.4

Airtecture Hall

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2.1

Hubert H. Humphrey Metrodome Architect: SOM

The Hubert H. Humphrey Metrodome in Minneapolis, Michigan uses low profile pneumatic roof and was designed by Skidmore, Owings, & Merril (SOM) The Metrodome’s roof structure is made of curved, double layered, Teflon coated fiberglass panels fastened to a skewed net of cables which span the dome. Weighing about 1.5 pounds per square foot, the roof is kept inflated by twenty 90-horsepower fans. It requires 250,000 ft³/min (120 m³/s) of air to keep it inflated. To keep the interior pressurized, every entrance uses revolving doors. The doublewalled construction allows warmed air to circulate beneath the top of the dome, melting accumulated snow. The Stadium has a central control room for the single purpose of monitoring the air pressure and maintaining the roof. Three times in the stadium’s history, severe weather has caused a collapse or deflation of the roof. Severe thunderstorms with extreme varying pressures have caused the roof to deflate in the past along with a very rapid accumulation of snow. The Pontiac Silverdome uses a very similar pneumatic system to support its roof. The decision to use a pneumatic roof was based on financial figures taken from the construction of the Silverdome.

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2.2

Texas Tech Practice Field Lubbock, Texas

The cables on the roof are covered with a protective fabric and when necessary are held together where they cross with metal clamps (top left). To drain rainwater off of the roof there are drains in the small brick wall that hides the compression ring that the cables are attached to at the base of the roof membrane (top right). There are also larger drains that lead off of the small brick wall that are hidden by brick turning them into aesthetic elements (far right). The Texas Tech practice field uses a very similar structural system as many larger pneumatic structures. The roof is air supported and the field itself is below grade making the low profile pneumatic roof appear to be a high profile pneumatic structure. Revolving doors are used at grade to enter the building (right). The larger loading bay doors are sealed off from the main field so they can be opened for extended periods without deflating the roof.

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2.3

The Tubaloon

Architect:SNØHETTA AS

Location: Kongsberg, Norway Typology: Performance Shelter Client: Kongsberg Jazz Festival Completed: June 2006

The “Tubaloon” is a large fabric cochlear shaped band stand designed for Norway’s Kongsberg Jazz Festival. It is a high profile pneumatic structure.The program called for a design that could be erected rapidly and that was tough enough to be taken down and redeployed elsewhere. The Tubaloon also posses acoustic qualities inherent in its design that keep small, quite performances intimate with its clamshell cantilever side while the PVC coated fabric has almost no effect on amplified performances. However the horn-like shape on the back of the Tubaloon amplifies louder performances. The combination of pneumatics with a tension membrane gives the Tubaloon a unique shape and appearance because of its internal structure. The steel skeleton that helps give the Tubaloon its shape is dependent on both the pneumatics and the membrane for support similar to the way the skin and tendons of the human body work to keep the skeleton correctly positioned. The structure of the Tubaloon consists of cables, rods, and fabric that create a

volume using an innovative structural technique called Tensairity. The structure of the Tubaloon was designed by Tensairity’s creator’s son Andrea Pedretti. He and one of SNØHETTA AS architects, Teas, adapted the traditional Tensairity beam, but instead of using helical cables he used galvanized-steel armatures. This method uses Tensairity beams composed of segments with brackets, which the air tubes nestle into. Instead of a by-the-book application of Tensairity, Tubaloon represents “an inflatable, tension-membrane structure in which most of the supporting structure is internalized,” Teas explains. The frame mounts to two poured-concrete foundation pads, with four additional connection points for cables and a compressor that maintains air pressure.

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2.4

Airtecture Exhibition Hall Architect: Festo

This temporary exhibition hall is one of the first pneumatic structures with a cubic interior and a structural system primarily supported by air inflated elements. The hall consists of approximately 330 individual air-inflated structural elements such as transparent window cushions made of Hostaflon ET, 40 Y-shaped columns, roof beams with translucent, intermediate membranes and pneumatic tension elements. A computer system controls the pressure in these different elements and actively changes based on dynamic environmental conditions such as precipitation or strong winds. The structure is considered to be lightweight and can be moved quite easily because most of the elements can be folded up when deflated. At each side of the expedition hall are two L-shaped pieces that come together to make the entrances. Above each “doorway” are vents to let air in and out of the hall. Each Y-shaped support on the exterior is held in place by three cables on each side ultimately connected to the “foundation” of the system.

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3.0

Study Models

3.1

Air Pressure 3.2

Bouncehouses 3.3

Seals

3.4

Seams

Air Flow

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3.1

Pneumatic Roof Study Model

Based on Metrodome and Practice Field



Structures using a large pneumatic roof span require the spanned space to be constantly pressurized. Although in some cases pressure can escape, the pressure loss is not significant enough to cause deflation even with smaller compressors or fans. For scaled down versions of pneumatic structure, like our study models, a regular air mattress pump provides plenty of air pressure. This pump is used in the same way as a larger version in the way it provides a constant stream of pressure.

In order to push and keep air inside the structure, a hole was left in one of the corners of the membrane. This hole was made to seal around the air pump. We discovered that the air pump put out so much pressure that as long as the air flow was pointed at the hole, no seal was required unless the roof was loaded. The combination of the duct tape (compression ring) and the string (steel cables) kept the membrane sealed against the base allowing the model to hold pressure.

Above is a study model of a pneumatic roof span. The membrane is relatively thin clear vinyl cut to the shape of the base. The base is a geometric shape as suggested in our research. String was used in place of the cables that would normally span the roof in order to hold the membrane down and keep it from breaking free from the compression ring. In this model duct tape along the bottom of the base acts as the compression ring.

Weight tests were undertaken to see how much live load the roof could hold. These tests are representative of the live loads of snow and ice that can cause a collapse in pneumatic roof structures. Various loads were added and were all held up by the roof. If scaled these loads would be more than what would ever be put on a real roof span. This model served its purpose in that it educated us on the potential of air pressure and showed us that air tight seals are not completely necessary.

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3.2

Seam Research Bouncehouses

We began to look at how air tight seals were made on high profile structures that did not involve compression rings or cables. On the Texas Tech University campus there were multiple inflatable bounce houses setup for an advertising event. These structures showed us an example of how seals could be made between various pieces of membrane. There are two kinds of seals: inverted seals and visible exterior seals. Both of these seals are done by stitching the edges together. The inverted seals are stitched then turned inside out in order to hide the edges of membrane. The visible seals are usually on the bottom to make them more out of sight giving the structure as a whole a more seamless look. The fan used to inflate these structures seems relatively small compared to the size of the structures. Also we noticed that the seals are not completely airtight in every instance. There is a small amount of air that is always escaping from somewhere but it is a negligible amount and does not cause the structure to deflate.

Visible seam

Inverted seam

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3.3

Air Tight Seam Studies Heat

Our initial attempt at sealing membrane together was done using heat. Using heat to melt the edges together seemed like the most effective way to get a completely air tight seal. To melt the vinyl membrane a hair straightener was used on medium heat.

To inflate these heat sealed elements a small hole was left along one edge and a straw was placed inside this hole. We then inflated these objects by mouth to test the heated seams. Most of the seams held but in some places we were able to burst the seams with just the pressure created by our lungs. Because of the failure of the pure heat seams we realized that a stronger seam was necessary. Inverted Seam

Visible Seam

This process involves heating up the two pieces of vinyl enough for the two edges to bind together. The best method to do this was to apply the heat for just one or two seconds. If the heat is left on the vinyl for much longer the plastic would melt and become so thin that it would lose its strength. If the heat is applied long enough holes and tears will begin to form and eventually the plastic will disintegrate.

Above are comparisons of our seal study to the seams on the bouncehouses. The inverted seams (top) are stitched and then inverted so they are inside the inflatable element. We mirrored this on the top edges of this seal study. Visible seams (bottom) are the seams that close the element so they must be on the outside. We mirrored visible seams on the bottom edges of our seal study. These visible edges were the last seals done.

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3.3

Seam Test

Clear Vinyl+Thread

We began testing seams with thicker clear vinyl and thread. The pure heat seams were not strong enough to withstand more pressure than we could generate with our lungs. With a sewing needle and thread we began making a larger version of our heat seal study but with stitching instead of heat. This larger study model was constructed with six pieces of vinyl cut and stitched together to form a rectangular shape.

To inflate this study model we used the air mattress pump from our earlier study model. In order to feed the air into the study model, we made a tube out of the clear vinyl and attached it to the study model in one of the corners. To seal the tube to the study model we cut the end of the tube into flaps and stitched these flaps onto the inside of the study model and then added heat as an extra sealing measure.

Two lines of stitching were used because two lines create an area of the vinyl that is held together tightly creating an airtight seal. Two lines of stitching are also stronger than a single line of stitching. The seam above is an inverted seam along one of the top edges of the study model. We decided to add heat to these seams as well as an extra sealing method. The stitching holds the pieces together and creates an almost airtight seam while the heat makes the seams completely airtight.

The finished study model has inverted seams along the top and sides and visible seams on the bottom edges. Once inflated the straight edges become rounded and the transition between the vinyl pieces becomes smoother. In two of the corners we left small gaps between the pieces of vinyl to release air so the seams would not be pulled apart by air pressure. This test showed us the strength of stitched seams and reinforced the idea that small holes to release air would not cause deflation.

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4.0

Materials

4.1

Bowers Project 4.2

Materials 4.3

Method

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4.1

Bower’s Project Material Research

Once we knew how to seal a membrane together to make an inflatable shape we began research on materials to make a membrane. We began to look for some kind of fiberglass sheet to stay true to the membranes used in many built pneumatic structures. We looked back at our research and began a search for a few of the coatings used to make these membranes. In searching for a place to purchase liquid polyvinyl chloride, which is often used to coat fiberglass panels to form a pneumatic membrane such as the roof of the Metrodome, we discovered an industrial supply company in Lubbock, TX that gave us an idea for a membrane from a previous project of theirs. Bower’s Plastics Distributors is a family owned company that supplies industrial materials most of which are plastic or rubber based. We described to them what we were attempting and they suggested that we use silicone instead of polyvinyl chloride to make a membrane. This suggestion was based on a custom air duct they made for an airplane in 1979. The problem they faced was in designing an induction system for a fuel injected Lycoming, which is an engine used in small airplanes. The problem arose from the sharp 180 degree turn that the 4” air hose had to make in order to clear the firewall next to it and supply air to the engine. The normal aeroduct hose they would have used could not make the sharp turn and then the curve needed to keep it from vibrating against the firewall which would cause the duct to fail.

To solve this problem a custom air duct was created by Layering fiberglass cloth coated in silicone in the shape they needed. Starting with a mold that had the curves necessary for the space, they cut strips of coarsely weaved fiberglass cloth, coated the strips in silicone, and then covered the mold in about six layers these strips. Once dry this duct was sturdy enough to hold its shape but still flexible. In order to paint on the thick silicone with a brush it had to be diluted down to a liquid form. This also helped the fiberglass cloth to absorb the silicone into the fibers. Tetrahydrofuran (THF) is the chemical used to dilute the silicon down to the point where it can be applied onto the fiberglass cloth with a paintbrush. It is a very fast evaporating chemical so once it is spread out on the fiberglass cloth the silicon becomes semi-cured very quickly. We were warned to only use this fast evaporating chemical in a well ventilated area or outside. It is a very strong plastic and rubber solvent and melts anything plastic. THF is very flammable, can cause rashes on the skin, poisons the body if ingested, and can damage the eyes. A single layer of fiberglass cloth coated in this way is almost just as flexible as the cloth by itself and we realized that this flexibility would make a perfect membrane for an inflatable structure because it is strong, stays true to pneumatic structures and does not allow air through it. All of the materials used for this project and in our tests can be purchased from Bowers Plastics who can be reached at (806) 763 5925.

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4.2

Materials

Membrane Materials

Following the suggestions from Bowers, we purchased a square yard of coarse weave fiberglass cloth to make a membrane similar to a built pneumatic structure. This sample is of fiberglass cloth made of twisted glass strands interwoven with a simple tabby (criss-cross) weave. The weave is very coarse and the threads separate easily if not held together. Some of those separations can be seen in the photo above.

The silicone we purchased to test out a single layer of silicone coated fiberglass cloth is 100% pure silicone rubber purchased in a tube. Silicon out of these tubes is too thick to easily spread around and would not be absorbed by the fiberglass so mixing it with the Tetrahydrafuron is necessary. Because THF evaporates at such a rapid rate, the mixture must be continuously stirred and monitored for consistency.

Polyethylene was another plastic like material we looked into for its potential as a membrane. The polyethylene sheets Bowers supplies are for greenhouses to control condensation. They have a waterlock on one side so that the material is only water permeable in one direction. This membrane allows air and light through but only will allow water through in excess amounts. We decided it would be too difficult to seal this material for an inflatable element but perhaps can have other uses.

Because THF is a plastic and rubber solvent simple rubber and latex gloves cannot protect the skin because the chemical burns right through them. The only gloves that can resist the effects of THF are Nitrile gloves. Nitrile is an organic compound that enabled scientists, beginning in the 17th century, to prepare and work with very toxic and volatile chemicals such as pure acids.

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4.3

Method

Material Test

To begin our test of silicon coated fiberglass we had to obtain a metal mixing container. The metal container cannot have a plastic coating on the inside or the mixture will melt off that coating and dirty the rubber gel. The Tetrahydrafuron should be added before the silicon to achieve the right consistency. Once the silicon is added, continuously stir and add in more silicon as needed. The consistency of the mixture should be similar to that of latex paint.

On a two to three inch wide strip of fiberglass cloth we tested different consistencies, colors of silicone, thicknesses of application, drying times, and double sided coating combinations. We were right in our initial assumption that a mixture with the consistency of latex paint would be necessary to get a smooth coat of this silicone gel mixture. The clear silicone seemed to brush on much smoother than the white possibly because of the white pigment.

Once the mixture is made a cheap, disposable paintbrush can be used to paint on the silicone gel. The material must be suspended in the air because any attempt to coat the fiberglass cloth while it is laying flat on a surface will cause the silicone to go right through the cloth and stick to the surface. This causes holes to form between the fibers when the cloth is pulled off of the surface.

After allowing the test strip to dry over night we came to multiple conclusions. We realized the best combination for aesthetic and practical reasons was one side white and the other side clear. In coating both sides of the cloth we formed a non-permeable membrane with surprising tensile strength as seen on the far right of this page. Our only concern that arose from this test is the weight of the membrane.

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5.0

Pneumatic Assemblage Design

5.1

Concept 5.2

Design 5.3

Calculation

Inflatable Elements - Section

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5.1 Elevation

Concept Sketches

Perspective

Front

Section

Inspired by the Tubaloon and its potential for providing temporary cover from the elements, we began sketching out a concept for a similar assemblage. Our concept was to create a large inflatable canopy-like structure that appears to only be held up by two cables. The idea is that there are two U-shaped inflatable elements one opaque and one clear to let light in. This assemblage will use three different membranes to block and let in light in certain areas. Our structure if scaled up would seem to be a monumental protrusion towards the sky that provides protection for the elements. The air mattress pump will provide the air pressure to keep the opaque element rigid enough to be held up by the two tension cables. There will be air tubes that run to each of the inflatable elements to keep them inflated with a continuous flow of air pressure. There will be a space between the feet of the inflatable elements that will be large enough for people to walk through and experience the space more completely.

Foot

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5.2

Design Drawings

As we began to refine our concept into a design the shape of the assemblage changed slightly. Once the structure is inflated it will become rigid and the cables, represented by the black lines, will be in tension holding the structure up off the ground. The two “feet” of the structure will be anchored to the ground as well but these anchors will be hidden making it seem like the structure is being held up only by two cables indicated by black lines in the sketch to the left. The red element in the sketch is the silicone coated fiberglass inflatable element. The blue shapes will be clear vinyl to let light underneath the canopy. The green hatched area will be the one way permeable polyethylene membrane to let light and air through but keep make rain drain off instead of passing through. The orange lines represent the air tubes that will supply air to the inflatable elements.

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5.3

Calculations

Inflatable Elements

Before cutting out the membrane we attempted to calculate exactly how wide the pieces of membrane needed to shrink to the correct width in plan view when inflated. We used simple geometry to figure out the circumference of the two pieces if they were inflated to a round shape. These measurements ended up only being partially correct because of how the elements acted when they were inflated. They ended up taking a more oval shape than a round one. The structure if scaled up would be 63’ by 42’ if laid down flat. The highest point of the canopy structure would be around 25’ but could be changed by changing the length of the cables. The silicon-fiberglass element would be 7’ in diameter while the clear vinyl elements would be 5’ in diameter. The opening between the feet would be 18’ feet wide. The scale that the assemblage will be built at is one 1” = 2.625’. We also figured out how far up the opening between the feet needed to start for different clearance heights and decided to make the opening 10’ high.

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6.0

Assemblage Construction

6.1

Main Membrane 6.2

Components 6.3

Build 6.4

Assemblage

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6.1

Main Membrane Silicone + Fiberglass

To make our primary membrane we repeated our silicon fiberglass test on a larger scale. We coated a 3’ by 3’ sheet of fiberglass cloth with white on one side and then clear on the other. Before the coats were even dry the membrane would catch the wind like a sail showing us that it was airtight. (bottom left) To cut out the correct shape we printed out the shape at the correct scale, cut it out, and pinned it to the membrane we had made. (below) We then proceeded to cut two of the shapes out of the membrane. From our study models we knew that two shapes stitched together would give us more of the form we wanted than one larger shape with a single stitched edged. To stitch the two pieces of membrane together we used a sewing machine to get a tight zig-zag stitch. The sewing machine allows us to work much more quickly than we could have if we stitched the membrane by hand. Also it provided a stronger, more reliable seam. We left small 3/4” wide gaps in the seam to give us a place to pump air into the element.

In order to make the clear vinyl elements, we used the same method as with the primary membrane. We used a sewing machine once again to stitch these elements. The sewing machine seams on the vinyl are air tight but have some skipping in them because the vinyl often would stick between the two metal pieces of the sewing machine. These stutters in the stitching do not affect the strength of the stitch however.

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6.2

Components Vinyl+Poly+Etc

In order to supply air to all of the components we needed to split the air flow coming from the pump into 4 separate tubes. We used 1/4” diameter clear tubing and siliconed 4 lengths of tubing into the detachable air mattress nozzle. We used wooden dowel rods to keep the tubes in place while the silicone dried. Once dry the silicone dried there was an airtight seal between the 4 tubes and around them successfully splitting the nozzle into 4 different air feeds. (above right)

In order to anchor the assemblage to its 1/2” MDF base, three different connections were required. Using eye hooks (above left) we connected the 1/16” cable to the base. We also used the eye hooks to anchor the feet to the base tightly. (above right) The extra fabric around the edge of the seam helped to hide these anchors as well as attach them. Then using two pieces of our membrane we made a sheath to connect the cable to the assemblage itself. (below)

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6.3

To put the components together, the extra 1/2” of fabric that was around every seam we made was stitched together. The U-shaped clear vinyl elements were hand stitched to the primary membrane because it was difficult to make the turn we needed when using the sewing machine. The smaller clear vinyl elements were stitched onto the primary element using the sewing machine however. The stitch used to connect all of these pieces is simply a single line of stiching. The tubing that feeds the U-shaped clear element was stitched on the underside of the assemblage along the stitch that connects the elements in order to hide it from view. (below left) We realized at this point that the air mattress pump we had, that was powered by batteries, could not supply enough pressure to inflate all of the elements. So we borrowed an air mattress pump that plugs into the wall (bottom right) which is much more powerful and used it to inflate the primary membrane while the clear vinyl elements were filled by the battery powered pump.

Build

Stitching components Together

We then proceeded to screw the eye hooks with the cables attached to them into the MDF base at the back corners. At this point we also attached the cable sheaths to the assemblage and then pulled the cables through to the correct lengths and finished both of the cable to assemblage connections.

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Rear perspective

Cable connection detail

Side view

Underside detail - stitched in tubing

Front view

Underside detail - membrane stitching

6.4

Assemblage Freestanding