Airborne Gravity 2010 - Geoscience Australia

Airborne Gravity 2010
GT-2A development summary
The development of the GT-2A sensor has been a great success. The new sensor has flown a large
number of repeat lines and grid surveys for testing and for commercial operations since September
2008. We have shown it capable of much higher survey production rates than the GT-1A sensor
during turbulent flying conditions, thus lowering acquisition costs. Although not yet flown on drape
flights with terrain relief significantly greater than 200 m, it should also prove capable of obtaining
better results than the GT-1A in both fixed-wing and helicopter installations.
With a large number of improvements in the sensor design, including higher specification components,
reduced noise, and a large increase in dynamic range, it has been possible to make a significant
improvement over the original GT-1A gravimeter. The GT-2A has sufficient dynamic range to keep the
survey aircraft flying in conditions which are barely tolerable for the flight crew.
Integration with new peripheral equipment
We replaced the original GT-1A control and data acquisition system (CDU) and also the original UPS
power supply in 2009 with more advanced products from Pico Envirotec Inc. (PEI) in Toronto. The
motivation for this integration of the GT-1A or GT-2A and new peripheral equipment is to more readily
meet the requirements of those customers who wish to purchase a complete geophysical system
including a gravimeter, rather than just a gravimeter itself. PEI peripherals are manufactured on a
larger scale, are more robust, and are also more readily serviced than the equivalent GT equipment.
New restraint system
Together with the engineers at Lake Central Air Services in Gravenhurst, Ontario, we developed a
new restraint system called the LCA00610 (Figure 18). The restraint cage, which faces forward in the
aircraft and is mounted to the same base plate as the GT-1A or GT-2A, is held to the aircraft’s seat
rails by four steel cables. This product is an improvement over the earlier method that required each
client to obtain their own installation approval on a case-by-case basis.
Figure 18. The new LCA00610 restraint cage has an aviation authority Supplemental Type
Certificate (STC) for installation in a variety of Cessna and Piper aircraft and can be readily
modified as required for installation in other aircraft types. (a) View looking aft. (b) Side view
showing restraint cables which attach to mounting lugs on the seat rails.
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