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  • Dust Off Those Air-Launched Space Concepts
    Posted by Graham Warwick 4:57 PM on Oct 19, 2011

    Over the years, there have been more air-launched satellite booster concepts than I have had curries. Now DARPA has come up with another one -- the Airborne Launch Assist Space Access (ALASA) program. DARPA prides itself in having no corporate memory, so the fact it has tried the air-launch approach before is of no concern to the agency.

    In fact, several previous DARPA air-launch projects are among the more than 150 past concepts listed in an interim report from the DARPA/NASA Horizontal Launch Study (HLS). The study, which looks at ideas dating as far back as 1981 (and the USAF's Air Launched Sortie Vehicle), is intended to identify horizontal launch system concepts. The interim report was released to help bidders for the ALASA program refine their ideas.

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    Focused on delivery of 15,000lb to orbit, the HLS has identified launch system concepts and potential subsonic flight demonstrators. DARPA and NASA studied top-mounted launch concepts based on 747. A380 and An-225 carrier aircraft, as well as bottom-mounted concepts based on a dual-fuselage C-5 and derivatives of Scaled Composites' White Knight. The interim report details several "point design vehicles" like the 747-400F-based PDV-2 above and a pair of potential demonstrators including the FTD-1 below, based on NASA's now-redundant 747-100 Shuttle Carrier Aircraft.

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    The two-stage liquid-fueled PDV-2 would boost 12,575lb to LEO, while the four-stage solid-rocket FTD-1 would lift 4,560lb - but ALASA looks to be much smaller, based in DARPA's notice of an industry day planned for Nov 4.

    "Currently, small satellite payloads cost over $30,000 per pound to launch. ALASA seeks to launch satellites on the order of 100lb [mass] for less than $10,000 per pound, or $1 million total including range support costs," the announcement says. The ALASA program is to include "development of an on-the-shelf complete launch vehicle requiring no recurring maintenance or support, and no specific integration to prepare for launch."

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    F-15 Global Strike Eagle (Concept: Boeing)

    ALASA sounds more like previous studies of F-15-based airborne launchers able to boost payloads from 200-600lb into orbit, depending on whether the launch vehicle is slung under or mounted over the fuselage (above). Or like Dassault's Airborne Micro-Launcher concept (below), which could place a 100-150lb payload into LEO from underneath a Rafale fighter.

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    Concept: Dassault

    There is also NanoLaunch, a team formed by Premier Space Systems, Space Propulsion Group, Spath Engineering and Whittinghill Aerospace to develop a nano- and micro-satellite launch capability using a two-stage hybrid-rocket booster dropped from under an F-15 (below, top). A mock-up of the initial suborbital NanoLaunch 1 was unveiled in August, strapped under a MiG-21 (below, bottom).

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    Graphics: NanoLaunch

    The ALASA announcement, meanwhile, outlines the advantages of an airborne launch platform, to include "allowing performance improvement, reducing range costs, and flying more frequently, which combine to reduce cost per pound." Also the airborne launcher can relocate and launch quickly from almost any major runway worldwide, reducing response time, while "launch point offset permits essentially any possible orbit direction to be achieved...[and] allows the entire operation to be moved should a particular fixed airfield come under threat,"
    DARPA says.

    Tags: ar99, DARPA

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