Andrzej Jeziorski/MUNICH

THE GERMAN Government has approved a further DM45 million ($32.5 million) funding package for the Grob Strato 2C research-aircraft programme, on the condition that altitude tests are successful.

The project ran into trouble in June 1994, when manufacturer Burkhart Grob demanded more Government money to fund unexpectedly expensive avionics and testing. Grob needed to cover an overrun of almost DM50 million above the original DM92.4 million budget.

The Federal Ministry of Research and Technology was originally to pay DM71 million towards the cost of the aircraft, and Grob's request that the state cover a further DM45 million led to a funding freeze which the manufacturer initially had to pay for out of its own coffers.

Grob says that the state funding is now back on schedule, and the additional money is now in the ministry's 1995 budget. It will be released once flight tests have proved the aircraft's performance at altitudes of 59,000ft (18,000m) to 66,000ft.

According to Grob, the Government will then fund the second phase of the development programme, which involves the conversion of the aircraft to mission standard, weight optimisation and certification to Federal Aviation Regulations Part 23.

The aircraft has just had the low-pressure chargers in its compound engines connected, and is ready for high-altitude trials as soon as weather permits, says Grob. The first trial, expected at the beginning of June, is to take the aircraft to 30,000ft, with subsequent flights taking place at 45,000ft, 60,000ft and an as yet unspecified ceiling.

Grob says that, although the aircraft's compound propulsion system has been ground tested in altitude chambers for more than 10h of operation at 78,700ft, the propeller performance at such altitudes is harder to predict. No altitude chamber was big enough to accommodate the aircraft's 6m-diameter, five-bladed, Muhlbauer propellers, explains the manufacturer.

The propulsion system is based on Teledyne Continental Voyager TSIOL-550 piston engines, with turbochargers connected in series supply sea-level-pressure air, maintaining a 330kW (440hp) power output, at up to 78,700ft.

The high-altitude trials, are expected to be completed by the end of June, clearing the way for second development phase. This stage will include the replacement of the current 56.5m-span wing with a new mission-standard wing, which will be some 600kg lighter.

The aircraft is to be operated by the German Aerospace Research Establishment for conducting atmospheric and meteorological research.

Source: Flight International