Near Space Maneuvering Vehicle

Ascender

The US Air Force has employed aerostats for some time and has learnt to appreciate the benefits of a vehicle that can loiter over a particular area for an extended period providing reconnaissance and communication facilities. However, current aerostats are tethered generally below 15,000ft and the US Air Force has decided to investigate the benefits of a semi-autonomous lighter-than-air unmanned vehicle that could operate in the uppermost reaches of the atmosphere, referred to as ‘near space’, for extended periods.

The proposed vehicle is referred to as the Near Space Manoeuvring Vehicle (NSMV) and the concept calls for the vehicle to loiter between 100,000 and 120,000ft in the region above fixed-wing aircraft and below low-earth orbit satellites. Currently this whole area of airspace simply isn’t used and yet a vehicle that could operate at this height would be free from attack by current aircraft, above the present generation of SAMS and clear of bad weather.

The US Air Force’s Space BattleLab and Space Warfare Centre, both located at Schriever Air Force Base, Colorado are pursuing the NSMV concept as a means of supporting theatre commanders with a system that can provide a more dedicated and responsive communications, intelligence and reconnaissance capability. The NSMV is designed to compliment rather than replace other systems like the Global Hawk and would free up this highly capable UAV for more urgent missions.

To validate the NSMV concept the Space Battlelab intend to use an unusual V shaped prototype air vehicle called ‘Ascender’ that has been manufactured by JP Aerospace of Sacremento, California. The first version of ‘Ascender’ is a 93ft long model that has already performed successful flight tests within a hanger. The next stage will be to begin flights of a 175ft version of ‘Ascender’ will the aim of climbing the aircraft to 1000,000ft, have it navigate between two points, loiter over the second point for a short period of time and then return safely to base. If initial tests prove successful, the next stage will be to mount a 100lb payload on the vehicle and launch it to between 1000,000 and 120,000ft where it would have to navigate for 370km, loiter for 5 days and then return to base.

Unfortunately, the NSMV project eventually ran into some design problems and two flight tests were considered unsuccessful. This prompted the USAF to transfer management of the NSMV away from JP Aerospace to GSSL, another company with considerable experience in airship design. However, when GSSL examined the NSMV design they came to the conclusion that it did not meet the USAF requirements and, as a result, the USAF decided to cancel the complete NSMV project.

Every recent conflict has shown that, despite the USA possessing a vast array of ISR capabilities, there have never been enough to meet the requirement. The NSMV concept could well present a relatively low cost solution that could give US theatre commanders exactly what they need. However, the NSMV concept still has to overcome some major challenges that effect all high-altitude airships; namely that operating at these altitudes, carrying a reasonable payload, requires a very large envelope to contain the necessary amount of helium required. The weight of the necessary supporting structure then creates propulsion problems, given the relatively low horsepower generated by the electrical motors that drive the propellers, particularly when the power generated needs to be significant to overcome the strength of high-level jetstreams. Nevertheless, although the NSMV concept has been put back on the shelf, I believe it will be revived when the necessary technology becomes available, and when it does eventually achieve its design goals, it may well be only the first of many such vehicles to operate in ‘near space’

Revised November 2006