Page Content (OCR)
we YQ spun up prior to launch with nitrogen gas and then pulsed at the rate of twenty-eight times per second after release. This produced suffi- cient plasma to lift the test vehicles to around 98ft Gin (30.0m), which was a limit set for rea- sons of range safety. However, the height limit was extended in October 2000 when an alti- tude of 233ft (71.0m) was achieved using a small spin-stabilised laser-propelled test vehi- cle during a flight lasting 12.7 seconds. On this occasion the same 10-kilowatt laser was used and the test was undertaken in conjunction with NORAD to ensure there was no acciden- tal irradiation of passing orbital satellites. Further tests have been undertaken and Myrabo has suggested the possibility of launching small vehicles to an altitude of 100,000ft (30,500m) using a 150-kilowatt laser followed by a launch to orbital height with a 1-megawatt laser. To achieve this the aviation quality aluminium used to construct the model would be largely replaced by silicone carbide and Myrabo has suggested the possi- bility of fitting a miniature mirror system to redirect some of the laser energy ahead of the model to create an Air-spike. This is exciting research and there seems little doubt that vehicles propelled by laser and microwave energy could become a real- within the classified domain and may have _ aircraft was built at Dryden Center (Edwards ity within the next fifty years. However, inthe | some near-future military application. AFB) by David Bushman and Tony Frack- case of the Lightship concept it would be phe- The transmission of power to aircraft re- | owiak and equipped with small photovoltaic nomenally expensive to establish a series of _ appeared in 2003 when two NASA teams arrays (similar to solar cells) at MSFC. huge orbital power generation platforms, — revived ideas first studied by the agencyinthe Whether or not this work might eventually which also have the potential to be used as__1970s. Engineers and scientists from the Mar- __ lead toa revival of interest in the concepts first weapons. Furthermore, an interruption of the _ shall Space Flight Center (MSFC) and Dryden _ promoted by Raytheon in the early 1960s is beamed power or a critical component fail- Flight Research Center combined their tal- hard to say at the present time, but the tech- ure within the Lightship could prove cata- ents to produce a small propeller-driven nology could be applied to small UAVs, with strophic. That said, it seems likely that model aircraft powered by laser illumination, the disc providing an ideal shape for collec- Air-spike technology is being developed which was flown indoors at MSFC. The model _ tion arrays. aircraft was built at Dryden Center (Edwards AFB) by David Bushman and Tony Frack- owiak and equipped with small photovoltaic arrays (similar to solar cells) at MSFC. Whether or not this work might eventually lead to a revival of interest in the concepts first promoted by Raytheon in the early 1960s is hard to say at the present time, but the tech- nology could be applied to small UAVs, with the disc providing an ideal shape for collec- tion arrays. 173 Exotic Propulsion Systems