# Fall Testing of the Personal Airborne Equipment Backpack: Ground and Flight Testing
###### Abstract  
This article evaluated the functionality and reliability of the personal airborne equipment backpack TL-98 before its launch in military parachute operations. An objective of this project was the verification of the TL-98's characteristics which could be important in terms of the safety of the operation of the parachute, i.e., its functionality and reliability during flight and fall tests. A major effort within this research was focused on the fall tests of the TL-98 in standard parachute operational conditions. The strength of the backpack's anchorage points (by which the backpack is attached to the parachute harness) was verified by flight test, where it was dropped from the aircraft at the maximum operating speed and at the maximum operating weight of the backpack; the backpack's maximum operating weight had been increased by multiplying the standard maximum operating weight by a safety factor of 1.2. During the fall tests of the backpack, after its disconnection from the parachute harness (during ground tests and the test during the test jump), the strength of the backpack's anchoring eye and the strength of the rope with which the backpack is connected to the parachute harness were verified. Another objective of this research was the collection of information to define the TL-98's rope lifetime, which serves for the dropping of the TL-98. To fulfill this goal, the impact forces on the rope during the backpack's fall were measured using a force sensor. The values of the impact forces were then calculated and compared with the values from the experiment. Using experimentally obtained results and their comparison with the calculated results, the lifetime of the TL-98 rope for parachuting operations was determined on the basis of predetermined criteria. p 2 The backpack has been assigned for the transport of parachutists' accoutrements and armaments after landing on ground or in water, and the backpack's carrier unit was constructed for long-distance road marches as well. The backpack is anchored on the carrier unit of the parachutists' equipment before a jump (Figure 2). During the jump phase, which starts with the jump from the aircraft and continues until the parachute's opening (free-fall included), it is necessary for the anchoring to be trouble-free and reliable, specifically in terms of force effects retarding the parachute's opening. After the parachute opening and during the flight and descending phase, a parachutist releases the anchoring system of the TL-98 backpack. Then the system performs a 4 m  
Figure 1: Personal airborne equipment backpack TL-98. Figure 2: Backpack TL-98 fastened to the OVP-80 parachute skydiver harness before jump. free-fall. The free-fall is pulled back by the rope and the backpack remains hanging under the parachutist (Figure 3). The main object of this study was the acquisition of information about the influence of the force effects of the discontinued fall of the TL-98 backpack on the objective rope. The defined goal was to determine the rope's lifetime in parachutist operations. The maximum total weight of the personal airborne equipment backpack is 50 kg. The stopping of the force impact power, which is generated during the free-fall, must be reliably absorbed by the rope. In the context of this project, it was necessary to define the frequency of rope use which ensures the rope's reliability and reasonably eliminates the rope's malfunction or breakage during parachutist operations. Several studies [1; 2; 3; 4; 5; 6; 7] were devoted to the issue of rope testing, but they are applicable to mountainering or to work done at heights using rope procedures. These studies provide procedures for testing ropes and the results of their testing. However, testing in this area is strictly regulated by standards, and in the European area these are, for example, the standards for static ropes (EN 1891) [8], for dynamic ropes (EN 892) [9] or for auxiliary ropes (EN 564) [10].