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Support Tower

     For the 25 km proof of concept tower, the dynamic peak load on the support tower is over 1,500 metric tons. At this point, the torque buffer has removed all lateral forces on the tower making the critical buckling load the driving design parameter. The support beams above 13 km are filled with hydrogen while the beams below 13 km are filled with air. All beams are 1.5 km long, have a radius of 1 m and a thickness of 0.75 mm. The material mass of each beam is about 10 tons. The material mass permits the maintenance, repair, and replacement of the beams by repair robots called BIMERRs.

     Beginning at the base of the torque buffer, it takes 24 beams to support the peak dynamic load of 1,500 tons. The beams are divided into four clusters connected with a support ring. For the hydrogen filled beams, the clusters are arranged in a 2 beam deep fashion. For example, at the first interface ring at 25 km, the clusters are arranged in a 2 beam deep by 3 beam long matrix. For the second interface ring at 23.5 km, the clusters are arranged in a 2 beam deep by 4 beam long matrix. Keeping the clusters 2 beam deep simplifies maintenance, repair, and replacement of the beams. The beam arrangement is illustrated here.

    Below 13 km, the beams are filled with air. More beams are required to support the load and the clusters switch to a 3 beam deep fashion. This makes maintenance and replacement a little more difficult but still possible. At the base of the tower there are approximately 600 beams. The clusters are arranged in a 3 beam deep by 50 beam long matrix. Each cluster supports a load of about 200 psi. Concrete with this pressure loading is readily available for the final foundation.

     Construction of the support tower is completed one level at a time using specially designed 500 m construction beams. Each layer of beams are connected by a monorail forming a multi-beam structure. The critical loading of the 500 m multi-beam structure is six orders of magnitude greater than that of a single beam. Once this layer is complete, two more layers are added using the same technique. An interface ring is added at the top of the 1.5 km multi-beam construction tower. One and half kilometer support beams are inflated and the construction beams are removed. This completes the first level of the proof of concept support tower. The remaining 15 levels are completed in a similar fashion.

    The tower for the operational system is from 100-150 km high and supports an estimated dynamic load 3,100 tons. The dynamic load consist of the rotating truss and ribbons, second stage launch vehicle and overcarriage, passenger and cargo elevators, research station, interface ring and torque buffer, and guy wires. For the second generation tower, the supports are inflatable rigid structures made of carbon nanotube composites. The inflatable supports at the base of the torque buffer are filled with hydrogen gas while the supports below 13 km are filled with air. Gas bottles are located at intervals along the tower to replace the hydrogen gas that disipates through the materials. The gas bottles are replaced during routine maintenance and repair.

Fisher Space Systems LLC

Space Track Launch System

     A more detailed review of the proof of concept tower can be found in the Proof of Concept paper. A review of the construction for the support tower can be found in the Proof of Concept - Addendum A. A review of the second generation tower can be found in the updated STLS Tower paper. Use the comment form on the contact page if you wish to comment on the STLS concept. Be sure to review the creative commons licenses. All comments and suggestions will be shared equally throughout the space access community.
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Updated Mar 2013