|Title of Invention||
A RETRACTABLE VARIABLE HEIGHT CONTAINER
|Abstract||ABSTRACT The invention provides a retractable cum variable height container for transporting and storing spacecraft under protected environmental and climatic conditions suitable for carrying out various tests. It comprises of a stowable fabric encapsulation system a top hat assembly, a drive device assembly, clamp band assembly, a plurality of telescopic support poles and a single point handling interface.|
The invention relates to a retractable cum variable height container for transporting and storing spacecraft under protected environmental and climatic conditions suitable for canning out various tests.
Program critical, high cost and delicate space hardware like spacecrafts built with pressurised tanks sensitive optics delicate electronics and hazardous chemicals need protection from various environmental hazards during transportation. The mechanical hazards include shock, vibration and handling loads. The climatic hazards include temperature, humidity, rain, dust, differential pressure, fire, etc. electro static discharge and RF radiation are electrical hazards. These hazards lead to one or the oleic kind of damage like functional impairment distortions, breakage, high stresses, condensation, corrosion, contamination and other forms of destruction.
The present invention provides a, retractable cum variable height container for transporting spacecrafts. In particular, it provides a transportation system for a class of payloads weighing in the range of 800 kg to 3000 kg. The new system caters to the movement of spacecrafts within the campus, between the spacecraft manufacturing and test facilities and short distance off-campus transportation. It is not applicable to long distance or air shipment of spacecrafts.
Spacecraft transportation system known in the prior art is made of metallic container, specially designed to carry spacecraft to launch sites and between manufacturing and test acuities. It protects spacecraft from various environmental hazards encountered during transportation. The design specialties
of the system include protection systems such as vibration isolation system, temperature and humidity control system, pressure equalisation system, nitrogen purging system, rapid decompression and other handling and maneuvering devices, designed to meet the specific requirements of various class of spacecrafts. Though these containers also sense the purpose of movement of spacecraft within the campus, it is an involved and time-consuming activity. As the distance traveled is very less, the packing and unpacking time is generally very much higher than the travel duration. These containers are generally designed with adequate structural rigidity' to withstand harsh environmental conditions envisaged during various modes of shipment. The need for reification imposes mass penalties and results in heavier containers. Heavy containers pose difficulties in handling, packing and unpacking of spacecrafts. Further, these containers arc to be loaded onto a high capacity diesel prime mover to transport to the designated test facility. The exhaust smoke by the diesel prime mover contaminates and brings down the cleanliness levels thereby halting the packing and unpacking process for a considerable duration due to the stringent cleanliness requirements for the spacecraft.
In addition, larger spacecrafts call for horizontal mode of containerisation, which in turn results in additional operations of tilting the spacecraft using specially built tilting table. Further, the spacecraft fuel tanks filled with simulation fluid prohibits the horizontal mode of containerisation and transportation. This constraint imposed by fuel tanks of spacecrafts, calls for filling and draining of fuel simulation fluid for every transportation. Due to the dimensional constraints in the facilities, at instances, it is inevitable that the some of the projecting subsystems and appendages of larger spacecrafts are
required to disassembled before containerisation and assembled back after transportation.
All the above said processes add up to the overall time for the test and preparation of spacecraft. As the fully integrated spacecraft undergoes rigorous tests at its final stages, the time saved during these test phases of spacecraft, which is generally closer to the launch schedule, is highly precious and helpfiil in the timely realisation of spacecraft.
The invention provides a solution to the problems of containerisation and transportation described herein above and caters to the need of frequent movement of spacecrafts between test facilities within the campus and short distance ofif-campus transportation.
The retractable cum variable height container according to the invention provides a quickly operable transport equipment built with a flexible encapsulation system and offers a hght weight flexible, modular and reusable transportation solution and yet meets all the fiinctional aspects of spacecraft transportation system. It combines the fiinctions of the spacecraft transportation system and a trailer.
The flexible encapsulation system forms the containerisation module and provides the volumetric envelope to accommodate the spacecraft being transported. Unlike the known spacecraft transportation system, it is made of flexible fabric encapsulation resulting in a very light weight system. The combined weight of the quick operable transport equipment including the trailer
is less than one fifth of typical capacity of similar known systems. This unique light weight feature of the present system permits to use low power prime movers, typically a standard battery operated electric tow tractors. These prime movers unlike diesel prime movers used in the prior art, do not contaminate the clean areas. Added to the above, due to light weight, a high degree of maneuverability is exhibited by the equipment according to the invention to enable packing and unpacking and related operations in the confined working space at the test facilities. The design reduces the overall time due to minimised operations.
The trailer used is custom built specially to meet the mobility at various test facilities supporting the spacecraft and subsystems. Other subsystems namely shock and vibration isolation system, nitrogen purge system and protection devices are derived from the prior art of spacecraft transportation system and integrated to the system according to the invention.
Accordingly the invention provides a retractable cum variable height container for transporting and storing of spacecraft comprising a stowable fabric encapsulation system, a top hat assembly, a drive device assembly, a clamp band assembly, a plurality of telescopic support poles and a single point handling interface.
The invention will be described in detail with reference to the accompanying drawings :
Fig. 1 shows a retractable cum variable height container according to the invention for transporting and storing a spacecraft.
Fig. 2 shows the flexible encapsulation system used in the retractable cum variable height container according to the invention in deployed condition.
Fig. 3 shows the flexible encapsulation system in stowed condition.
Fig. 4 shows the drive assembly for the flexible encapsulation system.
The retractable cum variable height container according to the invention comprises a flexible encapsulation system (1) which encapsulates the spacecraft. A well bed trailer (2) forms the support structure and offers mobility for the integrated system. It comprises a fixed rear axle and a steerable king pin mounted front axle. The well-bed construction of the chassis allows reduction of vertical height of the equipment. The spacecraft is supported on vibration isolation system (3), using a spacecraft mounting adaptor (4) at centre of the trailer. An interface ring (5) laid on the trailer provides sealing joint for the flexible encapsulation system. A battery operated tractor (6) is used to offer traction force to tow the system. Nitrogen purge system (7) provides a clean, inert atmosphere inside the encapsulation and maintains a positive inflation pressure. The inflation pressure imparts adequate stif&iess to the fabric encapsulation.
The description of the flexible encapsulation system and the brief introduction of the other sub systems of the quickly operable transport equipment are given below.
Figures 2 and 3 show fabric encapsulation system in deployed condition and stowed condition respectively. It comprises a fabric encapsulation (8), drive device (9), top hat assembly (10), clamp band assembly (11) and support poles (19). The fabric encapsulation system is made of a cylindrical bellow shaped inflatable enclosure made of air tight, weatherproof electro-static dissipative and high strength fabric. It is folded to a compact size and deployed to the
desired envelope to suit the size of spacecrafts. A motorised drive device (9) is housed inside the top hat assembly (10) and is used for the quick deployment and retraction while packing and unpacking of the spacecraft. The fabric has a cylindrical envelope in its deployed condition and is stowed like a bellow through circumferential zig - zag folding to a small size. In its deployed condition, a minimum radial clearance of 200 mm is provided around the static envelope of a spacecraft. The encapsulation is pressurised using nitrogen purge system (7) to maintain clean and inert internal conditions, prevent inflow of external ambient air and offer adequate stifihess to encapsulation.
A defined folding and unfolding pattern is achieved by virtue of rigid rings (12) and elastic cords (13) laid at alternate pitches along the height of the fabric encapsulation (8). The elastic cords laid in between two consecutive rigid rings are pre-stressed such that their circumferential length is less than the circumferential length of the rigid rings, by a predetermined value. This technique facilitates the folding of the fabric in a predetermined pattern like a bellow during stowing. In the extended condition, the self-weight of the fabric causes, the stretching of the elastic cords and thus maintaining the cylindrical envelope having diameter as that of rigid ring. The stowed encapsulation permits the unpacking of spacecraft using low vertical travel of cranes by moving the encapsulation side ways clearing the spacecraft between the support poles (19). In case of prior art, opening of the rigid metalHc covers need a vertical travel of crane nearly twice the height of spacecraft.
The diameter of the rigid rings defines the diametrical envelope of the encapsulation. These rings also resist the Hoop's stress due to internal pressure,
in addition to the resistance offered by the fabric. The inflated fabric along with rigid rings offers adequate stifihess to resist to inadvertent collision with any objects and bounce back objects falling on it. In addition, this technique improves the resistance to the wind loads during transportation avoiding localised sway of fabric. The resistance of the integrated system to wind load is improved by using guying slings connected to the trailer.
The fabric used for this encapsulation is specially selected to meet the strength requirements for withstanding the internal pressure. In addition, other major characteristics like the electro-static discharge requirements, weather resistance, tear resistance and out gassing are considered in selecting an appropriate fabric for this application. The process limitations of the tabric towards conductive coating, weather resistance coating and joining methods like bonding, stitching etc., are also considered while selecting the fabric.
Sealing elastomeric gaskets (14) are stitched and bonded at the top and bottom ends of the fabric. The top gasket is snug fitted with the shell of top hat assembly (10) and the bottom gasket is snug fitted at the interface ring of the well-bed trailer (2). Clamp band assemblies (11) are used to pre-stress the elastomeric gasket and provide a leak proof joint at top and bottom joints of the fabric encapsulation. Anchoring loops are provided on the fabric to hold the encapsulation on to the support poles (19). The wire ropes of the drive assembly (9) are connected to the terminals provided in the clamp band assembly (11). The necessary upward force required for stowing the fabric is applied through the wire ropes (15) by energising the drive assembly (9).
Fig.4 shows the drive assembly (9) for the flexible encapsulation assembly. It comprises wire ropes (15), guiding pulleys (16), winding spool (17) and gear drive with electric motor (18). The drive assembly enables raising and lowering of the encapsulation system by winding and unwinding of six wire ropes on to a spool driven (17) by a motor (18) similar to the operation of winches and cranes. By virtue of the pre-stress in the elastic cords in the fah«ic, the fabric follows a defined folding pattern while raising and unfolds back to cylindrical shape while lowering of the fabric. The drive assembly is housed inside the annular recess space of top hat assembly (10)
There are two clamp band assemblies used for fixing the encapsulation assembly. One of the clamp band assemblies is laid at the top hat assembly and the other is laid at the interfiice ring (5) of the well-bed trailer (2). Each clamp band assembly (11) consists of two halves of stainless steel flat bands circumferentially laid over the elastomeric gaskets (14) stitched and bonded at the top and bottom ends of the fabric. Retaining loops provided at the ends of the fabric hold the clamp band in position. The ends of the bands are connected through tensioning bolts. Circumferential sealing pressure is exerted on the elastomeric gasket (14) by applying tension to the band to ensure leak proof sealed joints at the interfaces.
Top hat assembly (10) is a rigid shell reinforced with ribs. Top hat assembly houses the drive assembly (9) and the flexible fabric encapsulation (8) in the folded condition. An annular rib on the top hat assembly forms the interface for the sealing joint of the fabric through an elastomeric gasket (14) and a clamp band. There are four hard points on the shell used as interface for telescopic
support poles (19). These telescopic poles (19), support all the parts of flexible encapsulation system while on the trailer (2) as well as while resting on the floor. A single point-handling interface (20) is provided at the center of the top hat assembly (10). A handling shackle attached at the centre of top hat assembly enables lifting of the flexible encapsulation system using a crane. A hand held remote actuator (21) is used to attach the handling shackle by operator standing away from the envelope of flexible encapsulation system. In addition, four hard handling points (22) are provided which enable handling of the top hat assembly. Four lashing brackets (23) are also fitted at these hard points.
The total system is hauled using prime movers meeting the required traction force. Standard battery operated tractor (6) is used for hauling between clean areas within the campus and a diesel tractor is used for off-campus short distance movements.
The following are the advantages in using the retractable cum variable height container according to the invention for transporting and storing the spacecraft.
1. It enables quick operation for packing and unpacking of spacecraft. Minimises number of operations and saves considerable operation time during the critical test phase of spacecraft.
2. The light weight design permits easy maneuverability within smaller and confined working laboratories and test facilities.
3. Low capacity towing prime mover is adequate to haul the system, tliereby it permits use of low capacitv' battery operated tractor. Thus contamination inside clean areas is eliminated.
4. Enables handling of larger spacecrafts at test facilities and laboratories having low bay buildings and low vertical travel cranes.
5. Permits the transportation of large spacecrafts in vertical condition, thereby eliminates the need to fill and drain the fuel tanks. This minimises the number operations on the fill and drain valves of the flight worthy spacecrafts. Also, need of tilt table and tilting operation on a flight worthy spacecraft is eliminated.
6. Flexible and modular design permits to augment to suit the spacecraft envelope.
The retractable cum variable height container according to the invention is designed only to meet the frequent movement of spacecrafts within the secured premises of the test facilities in the campus and short distance off-campus transportation. It may be used for surface transportation of by road but not suitable for air or sea shipment of spacecrafts. The maximum speed of transportation may be limited within 25 km'hr considering the stabihty of the system under wind loads.
1. A retractable cum variable height container for transporting and storing of
spacecraft comprising a solvable fancy encapsulation system (1) a top hat
assembly (10), a drive device assembly (9), a clamp band assembly (11), a
plurality of telescopic support poles (19) and a single point handling interface
2. The retractable cum variable height container as claimed in claim 1, wherein the said stowable fabric encapsulation system (1) comprises an anti¬static and weather resistant fabric (8) stitched with rigid rings (12) and elastic cords (13) in tandem to enable for stowing and extending the same with the support of drive assembly (9) and telescopic support poles (19).
3. The retractable cum variable height container as claimed in claim 1, wherein the said stowable fabric encapsulation system (1) is an airtight and resistant to internal pressure while pressurized with inert gases.
4. The retractable cum variable height container as claimed in claim 1, wherein the said top hat assembly (10) comprises a rigid shell made of a composite material reinforced with ribs and accommodate said drive assembly (9), said stoked fabric material and an annular rib to provide interface to clamp said band assembly (11).
5. The retractable cum variable height container as claimed in claim 1, wherein the said drive device assembly (9) comprises wire ropes (15), a
purity of guiding pulleys (16), a winding spool (17) and a motor with gear box(18j.
6. The retractable cum variable height container as claimed in claim I,
wherein Uie said clamp band assembly (11) comprises a top ring assembly
attached to the top hat assembly (10) and a bottom ring assembly attached to the
well-bed trailer (2).
7. The retractable cum variable height container as claimed in claim 6,
wherein each said top ring assembly and bottom ring assembly comprises two
halves of metallic tlat bands connected through tensioning bolts
circumferentially laid over elastomeric gaskets (14) tliat are stitched and bonded
over the top end and bottom end of the fabric (8).
8. The retractable cum variable height container as claimed in claim 1, wherein each said telescopic support pole (19) comprises two tubes of larger and smaller diameter with a plurality of holes along the longitudinal face to provide for varying the height of the container by sliding movement of the smaller pole inside the larger one and with a metallic pin to arrest sliding movement.
9. The retractable cum vanable height container as claimed in claim 1, wherein the said top hat assembly (10) comprises a rigid shell with a plurality of interface handhng points (22) placed circumferentially to enable lifting, moving and such other handling operations and a plurality of lashing brackets (23) placed circumferentially to enable the firm fixing of the said container to the
well-bed trailer (2) and a single point handling block (20) at the centre point of the shell to enable lifting operations with a handling shackle.
10. The retractable cum variable height container as claimed in claim 1,
wherein a handling ring is provided for attachment to a crane hook, a hand held
remote actuator (21) for connecting and releasing operations of the said
handling ring to the handling block (20) of the top hat assembly (10), through a
spring loaded pin.
11. A retractable cum variable height container, substantially as hereinabove
described and illustrated with reference to the accompanying drawings.
|Indian Patent Application Number||380/CHE/2003|
|PG Journal Number||26/2007|
|Date of Filing||05-May-2003|
|Name of Patentee||M/S. INDIAN SPACE RESEARCH ORGANISATION|
|Applicant Address||ISRO HEADQUATERS DEPATMENT OF SPACE, ANTARIKSH BHAVAN, NEW BEL ROAD, BANGALORE 560 094|
|PCT International Classification Number||B64G-5/00|
|PCT International Application Number||N/A|
|PCT International Filing date|