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The FireFly is a medium sized Precision Aerial Delivery System
(PADS) platform capable of delivering 500 lb to 2,200 lb (225
kg to 1.000 kg). With a 4:1 glide ratio and 25,000 ft deployment
altitude, the FireFly is capable of significant vertical and
horizontal standoff. The system has demonstrated excellent accuracy,
landing within 150 meters of the designated Impact Point over
80% of the time. When using the roadway landing feature, the
FireFly has a greater than 80% probability of landing within
50 meters of the designated road. FireFly uses a roadway landing
feature enabling the user to designate an azimuth for landing
rather than the default into-the-wind heading to take advantage
of roads and other paved surfaces for cargo retrieval.
The distance to the Impact Point for ram air canopies
is predominantly affected by the efficient glide capability
of the airfoil. Vertical deviations are multiplied by the glide
ratio of the canopy. In the case of the Airborne Systems JPADS
platforms, all canopies have a minimum 4:1 glide ratio meaning
that if the system is 10 meters too high on approach, the system
would overshoot the target by 40 meters. Left and right deviations
are not affected by the glide performance of the system so the
overall landing area has a rectangular shape as depicted by
the graphic at right. This rectangle is known as the Roadway
Landing Area.
If the system would approach the Impact Point
from any direction, the Roadway Landing Area would be equivalent
to the Circular Error Probable. However, by dictating the approach
azimuth, the system’s potential for error is decreased
significantly. If the system can be forced to fly a designated
approach, the left and right limits in the Circular Error Probable
do not apply and can be effectively removed from the potential
landing area, a 75% reduction in the total potential landing
area. The data at left are the results of test drops conducted
by Airborne Systems. The results clearly show that the concept
of the Roadway Landing Feature does greatly decrease the potential
landing area of the system.
Operational advantages of the Roadway Landing
Feature include the ability to land the system on a linear terrain
feature (road, ridgeline, long axis of a Drop Zone, etc.). Landing
the system on a road allows for easier recovery of the payload
and reduced exposure in a potentially hostile environment.
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