Geoengineering Final Report UC01-001; AR10-182 October 30, 2010
predicted for a gun system are heavily dependent on projectile payload fraction. With the 70 kg explosive payload replaced with geoengineering material the shells have a payload fraction of only 8%. This means to achieve 1M tonnes up-mass per year, 14,000,000 shots must be fired each year. A payload fraction of 50% was also analyzed to serve as a lower bound for cost. The barrel linings need to be replaced after approximately every 1,500 shots44 (about 48 hours of firing). If it is assumed that the barrels are removed for relining elsewhere and a fresh barrel is installed, we can assume this process takes an estimated 3 hours. Thus each gun is then available 93% of the time. Availability was reduced to 50% to take into account maintenance on loading mechanisms and other components. Crew costs are rather conservative, as the firing process can be automated. Labor is assumed to be 1 operator and 1 maintenance technician 24-hours a day for each barrel and 1 manager for 8 hours per day for each set of 10 barrels. The cost of setting up the guns and associated breach loading systems, projectile conveyors, and gun mounts is $7.5M per barrel. 8.2.1 Cost Estimate The gun based system was the cheapest to develop and acquire. This is due to the maturity of the technology involved, having been used on battleships for approximately 70 years. A gun system would require a large number of barrels with automated loading systems and barrel lining replacement systems. A rate of $7.5M per barrel was assumed for the construction of the gun loading and control systems. The largest expense associated with operating the guns is cost of projectiles. This is due to the 10% payload faction of a conventional 16”� projectile. Even though each projectile is relatively cheap at $3000 each, with 14M projectiles needed each year, costs are exorbitant. The recurring cost per kilogram to 21.3 km (100kft) altitude is $140. It should be noted that the cost per shot of $9,500 within the same order of magnitude as the National Academy value of about $15,000 per shot (adjusted for inflation) shown in Table 16. Table 16: Costs estimates for geoengineering gun system. Numbers based on Mark 7 U.S. Naval guns with a 10% payload fraction. Previous estimates by the National Academy of Sciences (adjusted for inflation) are included for comparison (50% payload fraction).
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Originally the linings lasted only 290-350 shots, but with the use of modern linings on powder bags, gaseous erosion was significantly reduced. (http://www.navweaps.com/Weapons/WNUS_1650_mk7.htm)
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