Airborne Gravity 2010 - Geoscience Australia

Airborne Gravity 2010
Figure 1. The Zeppelin NT-07 airship used for the survey program Botswana. It is seen mounted
on a mast truck, which holds the airship secure when on the ground. The engines on the side and
rear of the hull can also be seen; these provide vector thrust control at low flight speeds.
Table 1. Specifications and performance for Zeppelin NT-07.
Length 75.1 m
Hull diameter 14.2 m
Envelope Volume 8425 m 3
Maximum airspeed 60 kn (111 km/h)
Normal cruising speed 35 to 50 kn (65 km/h to 93 km/h)
Maximum rate of climb 360 m/min
Maximum rate of descent 300 m/min
Maximum endurance 22 h
Maximum range 1100 km
Design useful load 1850 kg
Operational Issues
As described by Hatch et al. (2006), airship payload decreases with temperature and height above sea
level. The airship deployed was close to its technical limits operating at an average altitude of 1250 m
ASL where summer daytime temperatures can approach 40 C. To accommodate the equipment
payload and allow sufficient fuel to conduct a reasonable sortie, a night-time program was
implemented. This operational modality was carefully vetted for safety and steps were taken to
mitigate risk.
With a very large surface area, unanticipated wind and thermals presented the most serious safety
issue to the airship during low-level flight. Conducting the flight program at night minimized the
influence of thermals. Weather was also a significant safety issue as there are violent storms during
the summer rainy season and relatively strong regional winds. The relatively slow maximum speed
reduces the ability of the airship to avoid poor weather and the pilots had to ensure they had sufficient
fuel to return to base if significant headwinds developed.
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