Safety Analysis of an Airship that Loses Buoyant Gas from the Hull 2018-01-1954
This study investigates the physical phenomena that affect a high-altitude airship in the presence of lifting gas losses from the hull. General atmospheric thermodynamics and basic physical principles are adopted to describe the behavior of an airship with envelope failures that generate buoyant gas dispersion or depressurization phenomena. Overpressure that could grant to maintain some controllability during a large part of the descent is assessed by mean of the thermodynamic model of the envelope in the presence of gas losses. An optimization of the inflation parameters is provided and the conditions for avoiding dangerous crashes on the ground and the potential recovery of a damaged vehicle, people and its payload. In particular, the requirements for a slow depressurization is computed by the equilibrium with the atmosphere and then how can it be possible to sustain controlled navigation are determined. A key factor for security relates directly to the capability of preserving some airship balloon overpressure for the longest time possible. This condition can extend much the range of control. Complete forfeit conditions will be determined. In some cases, specific maneuvers could allow configuring the deflated balloon as a parachute, if coupled with adequate safety systems. A general guideline for safety systems has been defined and they show that airship if well created and well governed in emergency conditions will be much safer than any other aerial vehicle.
Michele Trancossi, Jose Pascoa, Giuseppe Cannistraro
Sheffield Hallam University, Universidade Da Beira Interior, Universita degli Studi di Messina
Aerospace Systems and Technology Conference