Patent 3909992 - Inflatable ice igloo

United States Patent Patent Number 3,909,992
Stachiw Issued October 7, 1975

Inflatable ice igloo


A rapidly erectable shelter makes use of ambient, subfreezing temperatures o protect men and equipment. Three flexible layers are arranged to define a pair of hemispherical shell-shaped chambers. Pressurized gas is vented to the inner chamber, which serves as a molding form for water being pumped into the outer chamber. The freezing of the water creates a rigid shell of ice and the inner gas filled chamber insulates the interior and prevents melted droplets of the ice shell from dripping into the interior. In warmer climates or under water, self-polymerizing thermoset resins or a concrete slurry is substituted for the pumped water with identical results. Irrespective which material is chosen, the shelter is quickly erected by unskilled labor and provides an air insulation inside the rigid shell.

Inventors: Stachiw; Jerry D. (Lakeside, CA)
Assignee: The United States of America as represented by the Secretary of the Navy (Washington, DC)
Family ID: 23796005
Appl. No.: 05/452,312
Filed: March 18, 1974

Current U.S. Class: 52/215 - 135/115 - 135/1201 - 52/816
Current CPC Class: E04B 1/169 (20130101); E04B 1/3211 (20130101); E04H 15/20 (20130101); E04B 2001/3217 (20130101); E04H 2015/207 (20130101); E04H 2015/206 (20130101); E04B 2001/3264 (20130101)
Current International Class: E04B01/16 (20060101)
E04H015/20 (20060101)
E04B01/32 (20060101)
E04B0001/345 ()
Field of Search: ;52/2,63,80 ;264/32,35

References Cited [Referenced By]

U.S. Patent Documents
2649101 August 1953 Suits
2812769 November 1957 Schaefer
2939467 June 1960 Meyer
3118010 January 1964 Harrington
3213628 October 1965 Serota
3258883 July 1966 Campanaro
3357142 December 1967 Farrer
3388509 June 1968 Mora
3611648 October 1971 Barnett
3643910 February 1972 Hiefetz
3660951 May 1972 Cadwell
3686818 August 1972 Bini
3726950 April 1973 Tarzillo
3739536 June 1973 Ward
3851487 December 1974 Lambertsen
Foreign Patent Documents
727,970 Mar 1955 GB
Primary Examiner: Ernest R Purser
Assistant Examiner:Henry Raduazo
Attorney, Agent or Firm: Sciascia; Richard S. Johnston; Ervin F. Keough; Thomas Glenn

Government Interests


The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A rapidly erectable shelter for subfreezing climes comprising:

first means for enclosing a first shell-shaped chamber having a first fitting communicating therewith, said first shell-shaped chamber has a width sufficient to provide insulation and to reduce the problems associated with condensation on the inside of said rapidly erectable shelter;

a source of pressurized gas coupled to said first fitting to distend said first enclosing means to define a first shell shaped chamber;

second means for enclosing a second shell-shaped chamber having a second fitting communicating therewith, said second shell-shaped chamber is sized to be larger than said first shell-shaped chamber to be disposed adjacent to and supported by said first enclosing means when said first enclosing means is distended by said source of pressurized gas;

the first enclosing means and the second enclosing means are flexible sheets shaped and arranged to form a three-walled, two-chambered hemispherical shell; and

a source of water coupled to said second fitting for filling said second shell-shaped chamber, said water freezes to the solid state after being introduced into said second shell-shaped chamber thereby forming the supporting structure for said rapidly erectable shelter while said first shell-shaped chamber serves to insulate and to prevent droplets from forming in the interior of said rapidly erectable shelter.

2. A rapidly erectable shelter according to claim 1 further including:

a pair of fabric layers for forming a floor for the three-walled hemispherical shell and being secured across the periphery thereof, the layered floor having a fitting to allow its distention for insulating the interior of said rapidly erectable shelter.

3. A rapidly erectable shelter according to claim 2 further including:

a multilayered entryway for permitting access to the interior of said shelter extending through said flexible sheets.

4. A rapidly erectable shelter according to claim 3 in which said three-walled hemispherical shell is provided with an opening for ventilation and heating and the layered floor is provided with a floor hatch.

5. A rapidly erectable shelter according to claim 4 further including:

means connected to the layered floor for extending beyond said periphery of said three-walled hemispherical shell and

means carried on the extending means for defining an annular retainer and annular trough, said extending means and said annular retainer cooperating to collect said water to anchor said rapidly erectable shelter.


Portable shelters, particularly those which are erectable upon short notice, are many and varied in design. While tents are lightweight and easy to put up, they leave much to be desired in strong winds and extreme cold. Prefabricated structures employing rigid insulated panels have usually provided adequate shelter in a hostile environment. Unfortunately, however, hauling these structures to a work site creates a formidable logistics problem and a relatively uncomplicated movement of men and equipment mushrooms into convoy-like proportions. The difficulties encountered during polar operations are augmented by the burden imposed by the transport of the bulky, prefab shelters. Inflatable structures have been used to some degree of success and are, by and large, not as heavy and space consuming as the prefab structures. Usually the inflatable shelters consist of a number of air-filled sacks which are bonded and sewn together to form a sausaged-shaped structure. The frequent polar storms pose a threat to the conventional inflatable structures and, upon occasion, they are blown flat or uprooted by the severe winds. When gale winds strike, anchoring them with a considerable number of stakes often fails to prevent their being ripped apart. In addition, where the structures are to house machinery and equipment there is the ever present danger of snagging or puncturing and deflating the entire structure. One long appreciated and well known structure for arctic climes is the ice igloo. This ingenious habitat provides protection from intense cold and high winds. The ice igloo is one of the best engineering designs for a polar environment since it utilizes a readily available self-bonding ice which has a high mechanical strength and a low heat transfer coefficient. However, the igloo has several drawbacks. The construction of an igloo is a lengthy procedure and when the temperature inside the igloo is brought above freezing, the inside of the walls begins to melt. Water drips on the occupants and anything that happens to be inside the igloo and the humidity level rises. while the occupants can tolerate a certain amount of moisture, some electronic instrumentation can't, and its reliability falls considerably. Thus, there is a continuing need in the state-of-the-art for a rapidly erectable structure for polar climes which is capable of affording adequate shelter and which is essentially moisture-free.


The present invention is directed to providing a rapidly erectable shelter. A first hemispherical shell-shaped chamber is coupled to a source of pressurized gas and after the first chamber has been inflated, a second hemispherical shell-shaped chamber is disposed adjacent to and is supported by the first chamber. Water is pumped into the second chamber and freezes into ice, thereby forming an ice shell around the first air filled chamber. The ice shell withstands the effects of the harsh environment and the air-filled inner chamber insulates the interior to prevent the melting of the ice shell.

It is a prime object of the invention to provide a rapidly erectable shelter.

Another object of the invention is to provide a rapidly erectable shelter constructed from the materials at hand.

Still another object is to provide a shelter ideally suited for polar climes.

A further object is to provide a shelter which is fabricated from the materials at hand.

Still another object is to provide a shelter employing an air-filled chamber as a molding surface for an adjacent chamber.

Still another object is to provide a rapidly erectable shelter having an inner air-filled chamber supporting and insulating an outer ice-filled chamber.

Yet another object is to provide a shelter which is compact and easily transportable.

A further object is to provide a shelter employing an air-filled chamber as a molding form for a self-polymerizing resin.

Another object is to provide a rapidly erectable shelter ideally suited for undersea deployment.

Another object is provide an undersea shelter employing a water-filled chamber as a molding form for concrete.

These and other objects of the invention will become more readily apparent from the drawings when taken with the ensuing specification.


FIG. 1 is an isometric depiction of the invention.

FIG. 2 is a cross-sectional representation of the invention generally taken along lines 2--2 in FIG. 1.

FIG. 3 is a cross-sectional representation of the invention prior to erection.

FIG. 4 is a cross-sectional representation showing the pressurized chamber distended.

FIG. 5 is a cross-sectional representation showing the molding chamber being filled with the water partially frozen.

FIG. 5a shows a section of hardened resin.

FIG. 5b shows a section of set concrete.


Referring now to the drawings, FIG. 1 shows the preferred embodiment of the invention in the form of an inflatable ice igloo 10. Such a structure more than adequately provides shelter for men and equipment in a harsh polar environment. Due to its unique, sturdy construction, it is able to withstand a gale-like wind, yet there is no compromise in the speed at which it is erected.

Looking more particularly to FIG. 2, inflatable ice igloo 10 is fabricated from three main structural components, an inner fabric layer 11, a middle fabric layer 12, and an outer fabric layer 13.

The materials chosen for the fabric layers, as well as other flexible or fabric components to be described, are selected from commercially available fabrics. Since it is intended that the igloo is to be erected in the cold outdoors, the fabric must remain flexible in subfreezing temperatures. It must be heavy duty enough to resist puncturing and tearing during handling, yet, not so heavy as to sacrifice portability. Also, the material must resist deterioration by air and sunlight. There and other design parameters have led to the selection of a thirty thousandth of an inch neoprene-coated nylon fabric as a suitable material. Other state-of-the-art materials optionally are selected.

The three fabric layers are tailored in a hemispherically-shaped configuration and are slightly differently dimensioned with respect to one another. After they are sewn and bonded together along their lower edges, a hemispherical shell-shaped pressurized chamber 14 is created between inner fabric layer 11 and middle fabric layer 12 and, a slightly larger hemispherical shell-shaped molding chamber 15 is formed between middle fabric layer 12 and outer fabric layer 13. A fitting 16 is mounted to extend through inner fabric layer 11. The fitting is of conventional design and functions as a passageway and retainer for pressurized fluid on its way to and in pressurized chamber 14. A substantially identical fitting 17 is located at the top of the inflatable ice igloo and serves to allow the filling of molding chamber 15 with any one of a variety of liquids to be further described below. An auxiliary fitting 18 is mounted near the bottom rim of the molding chamber and can be used either to facilitate the filling or the draining of the chamber.

An entryway 19 is provided in the igloo and the fabric layers around the opening are sealed appropriately to maintain the integrity of the two chambers.

A hatch cover 20 is sized to cover the entryway and is joined to the outer surface of outer fabric layer 13 via a length of flexible strap 20a. The hatch cover is made up of three interconnected flexible panels 20b, 20c, and 20d. A fitting 20e reaches through innermost wall 20d to allow the passage and retention of a pressurized fluid into the envelope created between walls 20c and 20d. Similarly, another fitting 20f reaches through outer wall 20b and into the envelope created between walls 20b and 20c.

Since, in this preferred embodiment, it is intended that the ice igloo be used in polar or arctic regions, additional warmth in the interior is ensured by the inclusion of an inflatable floor 21 suitably affixed to the inner, middle, and outer fabric layers along its circumference. The floor is fashioned from upper and lower fabric layers 22 and 23, and is bonded onto the lower inner rim of inner fabric layer 11. A fitting 24, similar in design and function to the aforedescribed fittings, communicates with the space defined between the upper and lower fabric layers. After the space is inflated, an insulative layer is provided between the interior of the igloo and the ice or snow on which the igloo rests.

Because it is intended that the inflatable ice igloo will be used to support diving operations through the polar ice, a lower hatchway 25 extends through the upper and lower fabric layers. An inflatable hatch cover 26 is sized to cover the hatchway and is formed from three adjacent layers of flexible material. Hatch cover 26 differs from hatch cover 20 by the inclusion of an opening 26a and a single fitting 26b. The reason for this modification is that usually the entire interior of hatch cover 26 is filled with pressurized gas. Pressurized gas is chosen for its insulative properties and, because gas does not make the hatch cover excessively heavy.

On occasion, winds of gale force must be endured, and the weight of the igloo alone may not be sufficient to hold it in place. For this reason, a skirt 27, which is an extension of lower fabric layer 23, reaches out beyond the limits of the outer fabric layer 13. Covering the skirt with dirt, ice or snow helps hold the structure in place. An annular retaining wall 28 is connected to the outermost rim of the skirt and, when distended via a conventional fitting 29, an annular trough is created between the retaining wall and the outer fabric layer. The size of the trough is such as to allow the retention of a sufficient amount of weight.

As an added feature, an opening 30 is made through the inner, middle and outer fabric layers near the top of the igloo. This opening serves as a duct for ventilation or for a stove pipe. An inflatable plug 31 is included to close the opening when ventilation or heating is not called for.

Referring more particularly to FIGS. 3, 4, and 5, a source of pressurized gas 32 is coupled to fitting 16 by a hose 33. Pressurized gas is fed to the hemispherical shell-shaped pressure chamber 14 and this chamber is inflated, note FIG. 4. A sufficient pressure is fed to the interior of the pressurized chamber to raise it to its hemispherical configuration and to provide enough strength to support hemispherical shell-shaped molding chamber 15 as it is filled with a suitable material. At this point, or later in the igloo erecting procedure, inflatable floor 21 is inflated via its fitting 24 and the hatch covers and the annular retaining wall are inflated.

When the aforedescribed structure is to be an ice igloo, the suitable building material is water 34, see FIG. 5. A motor pump unit 35 draws in water through a hose 36 and expels it through a hose 37. The opposite end of hose 37 is connected to fitting 17 and water thereby reaches molding chamber 15. Optionally, the motor pump unit is inside the igloo and hose 36 draws in water through hatchway 25.

Thickness of the ice, i.e. the width of the molding chamber is designed as a function of the desired size of the igloo and the amount of time that it takes to erect the structure. A thin ice shell freezes faster than a thicker one, yet the thicker shell is more rugged. In either case, since there is a gradual pumping of water into the molding chamber, there will be a gradual, progressive freezing of the liquid water to the solid ice form 34a. A solid hemispherical shell being built up in the molding chamber supports itself as it assumes the hemispherical shell-shaped configuration.

A sufficiently fast water flow rate should be maintained to avoid freezing and blocking the flow of water in the upper portion of molding chamber 15, before it is frozen in the lower portion. After the water has frozen to form a complete hemispherical ice shell, the source of pressurized gas 32 is disconnected. The ice shell is of a shape and material composition which bears its weight and the weight of the fabric layers. Usually this weight is sufficient to hold the igloo in place during severe winds. If additional weight is needed, annular retainr 28 is filled with either pressurized gas or water and the annular trough is filled with water, snow, or any other material at hand.

The pressurized chamber 14 is left inflated to insulate the igloo interior from the frozen ice shell. The gas-filled, pressurized chamber prevents, or at least retards, the condensation of moisture on the inner surface of inner fabric layer 11. Personnel and equipment are kept dry by the pressurized chamber.

The disclosed ice igloo is rapidly deployable in a matter of minutes by unskilled personnel. In addition, this shelter is fabricated from materials at hand, i.e., water, to reduce the logistics effort. The inherent ruggedness of the neoprene coated nylon fabric from which the inner, middle, and outer layers are fashioned, provides a structure capable of resisting damage during transport, erection, and use.

The structure thusly described is superior with respect to the typical Eskimo ice igloo; this invention is erectable in terms of minutes as opposed to hours for the Eskimo variety; experience has demonstrated that the invention can be made much larger than a conventional Eskimo ice igloo; and the invention is much warmer, since the captive air space in pressurized chamber 14 separates the ice from the igloo interior.

In the embodiment just described, the ambient cold functions to freeze the water in the molding chamber to form a rigid, protective shell of ice. In warmer climates, that is, climates having temperatures above freezing, other materials are substituted for water. Erection of a modified "ice" igloo is substantially as outlined above. The only exception is that a different type of material which changes from the liquid to the solid state is pumped into molding chamber 15. One such material is a self-polymerizing, thermoset resin 38 or solids having low melting temperatures, sulfur, for example. Although the expense of these materials is considerably greater than water, these materials may be suitable when the urgency for a rapidly erectable shelter offsets the expense involved.

In a totally different environment the aforedescribed igloo functions to provide an underwater habitat. The non-erected structure looks somewhat like the invention in FIG. 3. The structure is positioned so that a piece of marine equipment, not shown, extends through hatchway 25. Next, the previously relied upon source of pressurized fluid, a motor pump unit similar to motor pump units 35, is coupled to fitting 16. Ambient seawater 34 is drawn through the motor pump unit and fed to fitting 16. The pumped water causes the distention of pressurized chamber 14 and a molding form is created by chamber 14 on which molding chamber 15 derives its shape.

A slurry 39 of concrete or bottom sediment is fed through fitting 16 into the molding chamber. As is the case whenever concrete is being poured, care must be taken that the molding chamber is completely filled before the concrete slurry sets. Otherwise, the structural integrity of the igloo is compromised.

Because of the great weight of the hardened concrete shell, the igloo is stable even in strong currents. The igloo now is capable of sheltering men and equipment. Optionally, the interior is gas filled for life support or work details. When the igloo is gas filled, usually it is wise to add ballast on skirt 27 to offset the added buoyancy. Water is pumped from chamber 14 to help lower the humidity.

Obviously, many modifications and variations are possible in the light of the above teachings and it is therefor understood that the invention may be practiced otherwise than specifically described.

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