General Atomics' Altus remotely piloted vehicle (RPV) is expected to move to NASA's Dryden Flight Research Center in California by early August to begin a month-long flight test programme.

The Altus, a derivative of the company's Predator military UAV, has been developed to demonstrate technologies for NASA's environmental research aircraft and sensor technology (ERAST) programme.

Like the Scaled Composites D-2, the Altus is aimed at technologies leading to a long-duration - 12h to 72h - high-altitude vehicle that would carry science payloads.

Altus begins the August test effort after completing trials at nearby El Mirage, where various improvements to the aircraft's Rotax 912 engine such as the installation of a two-stage turbocharger and intercooler have been under initial evaluation.

Developed by Thermo Mechanical Systems, the turbocharger and intercooler are vital to General Atomics' attempts to get the Altus to altitudes of 60,000ft (18,300m) and more.

The company achieved altitudes of 43,000ft with a single turbocharged engine, and hopes the modified powerplant will be able to sustain altitudes of 60,000ft for up to five hours.

The vertical fin has been modified to house an enlarged air scoop for the intercooler, and fuel capacity has been increased to about 380 litres (100 US gal).

"Although this will slow down the rate of climb, they're pretty confident it will increase the high altitude endurance," says NASA.

Apart from the propulsion system changes, the RPV's other vital statistics remain basically unaltered, with a wingspan of 16.8m, a length of 7.2m and a maximum speed of about 100kt (185km/h).

Following its Dryden test phase, the Altus will be moved in September to the Pacific Missile Range in Hawaii, where the vehicle will be used in an atmospheric radiation study for the US Department of Energy.

Source: Flight International