Affordable Access to Space (AAS): Towed Glider Air Launch System (TGALS)

The objective of the Towed Glider Air Launch System (TGALS) Project is to demonstrate the use of a remotely piloted, towed glider as a platform for the air launch of a small satellite launch vehicle.  Phase I of this project will demonstrate performance and operation of a scaled, towed glider launch platform. Phase II will test a full scale towed glider launch platform, including launching a small satellite into low-earth orbit. Initial funding of the scaled glider is provided by NASA's Center Innovation Funds and the Space Technology Mission Directorate, Game Changing Development Program. Further funding is sought from NASA partnership with industry, the Department of Defense, and academia.  Ultimately, if it proves feasible, NASA envisions the adoption of this technology and approach to air-launch by commercial launch providers.

Project Summary "By investing in bold, broadly applicable, disruptive technology that industry cannot tackle today, the Space Technology Mission Directorate (STMD) seeks to mature the technology required for NASA's future missions in science and exploration while proving the capabilities and lowering the cost for other government agencies and commercial space activities." So says the STMD's introduction on its NASA.gov website. The Towed Glider Air Launch System (TGALS) Project, sponsored by STMD, seeks to demonstrate one such technology that could significantly reduce the cost and improve the efficiency of sending small satellites into orbit. That technology is the use of towed-gliders for the air-launch of small launch vehicles (LV). The TGALS Project is a two-phase effort of NASA's Armstrong Flight Research Center. Phase I, partially funded through NASA's Center Innovation Fund and the Space Technology Mission Directorate, Game Changing Development Program, will develop and test a scaled, twin-fuselage glider in a series of flights to study towline dynamics, characterizing forces and optimizing line position. This will be followed by the horizontal release of a similarly-scaled LV. Phase I concludes with the development and test a sustainer motor that will provide the energy to boost the glider to a high pitch attitude and climb for launch angle optimization. Phase II, currently unfunded, will see the development and flight test of a full-scale remotely piloted glider, the development of a small LV, and the launch of a CubeSat satellite into Low Earth Orbit (LOE). Advocacy The goal of the TGALS Project is to enable candidate small launch vehicle companies to become viable commercial launch providers for putting small satellites into LEO on demand. There have been promising programs in this area in the past, but they have failed to produce the desired results. Recent developments in "small launch" technologies are placing dedicated small launch on the cusp of being viable. But an investment is needed to ignite the small launch market and make Operationally Responsive Space (ORS) and Launch-On-Demand a reality. An enabling function is required to reach the tipping point. Three elements must come together to provide this enabling function. The platform must be developed and demonstrated, small launch vehicle development must be fostered, and FAA policies for launch of small LVs using a glider launch platform must be established. Platform development has begun with the assembly and initial flight tests of a small scale, twin-fuselage glider. There are several advantages of using a glider rather than a conventional aircraft for air launch. First and foremost is efficiency. A 2012 feasibility study commissioned by NASA Langley Research Center concluded that a 100' wingspan remotely-piloted glider towed by a minimally modified business jet could safely and effectively release a 6,000 lb LV with a 100 lb satellite at a 70 deg. angle and 40,000 ft altitude. A reputable aircraft manufacturer has submitted to the project that it should be possible to build a high maximum lift-to-drag ratio (max L/D) aircraft structure that can carry twice its own weight, or a carry efficiency of 2.00. The current state of the art for carry efficiency among carrier aircraft is around 0.7. Further, launching at an inclined pitch attitude can provide additional performance increase over horizontal release for the LV. The second advantage is lower cost.  It is relatively inexpensive to build a glider versus a conventional, direct-carry aircraft. Maintenance costs are lower compared to a conventional aircraft. Many exiting business jets are candidate tow vehicles. No new infrastructure is needed for this glider air-launch system, potentially enabling small LV companies to get started without large capital outlays. The next advantage is safety and mission assurance. Remotely piloted gliders greatly reduce the risk to the pilot in the event of LV malfunction. In the event of a launch abort, the glider can land with the LV attached. And a restartable sustainer motor can extend glide home distance following launch or even after an abort. The final advantage is flexibility. Gliders can be staged at any airport, ready for immediate launch. Alternately, a glider and LV could fit inside a C-17 tow plane for transport to a desired airfield. The glider's plug-and-play center-wing interface allows multiple simultaneous LV build-ups, and the glider design is scalable up to LV sizes approaching 750,000 lbs. The towed glider design concept is the optimization of air launch for particular launch applications. The TGALS Project will include an Agency-led effort to coordinate government policies and procedures to address the needs and issues associated with dedicated small-sat launch. These issues include the appropriate safety requirements for small LVs, certification of tow modifications to existing aircraft, policies and regulations for servicing small LVs at airfields, streamlining launch-on-demand type operations, conjunction assessment processing, orbital debris mitigation, and international policy. The goal is to ensure that NASA, the military, and the government at-large are prepared to accept and support the small satellite launch industry. NASA requires strong external partnerships to move forward with the TGALS Project. NASA will provide procurement and labor for Phase I tasks and will provide labor for Phase II. External partners are expected to provide the procurement funding for Phase II.   The first flight tests of the scaled twin-fuselage glider have been successfully accomplished at NASA Armstrong Flight Research Center with the help of the Dryden Remotely Operated Integrated Drone (DROID), as the tow aircraft. Tests will continue to build confidence with the aircraft and tow operations before the test release of a representative LV. Excitement is building within industry and partners with an interest in Launch-On-Demand. Now is the time to commit to the next step, to Phase II and the full realization of this game changing technology. Phase I Deliverables • Performance and operations demonstration                                       FY15/Q2 • Sustainer Motor Development and Flight Test                                   FY15/Q3 • Phase II Proposal to STMD / Tech Demo                                         FY15/Q3 Phase II Deliverables • Towed Glider System Development & Build-up Flights                      FY16 - 18 • Small LV Integration Program                                                         FY16 - 18 • Policy Development and Coordination                                             FY16 - 18 • Launch Demo and Tech Transfer                                                    FY18