Aircraft Safety has been a subject of much research. Many commercial aircraft disasters have been caused by the detonation of small explosives in either the cargo hold or the cabin. Due of the ambient pressure differential between cabin pressure and external atmospheric pressure for an aircraft flying at altitudes above 20,000 feet, even a small explosion can cause massive structural failure because of this heightened stress on the aircraft structure. This basic problem of pressure equalization became my subject for summer research. It was our goal to find a method that would intentionally vent an aircraft both reliably and quickly in the event of anon-board pressure spike.

In 1953 Fritz Haber and Hans Clamann published a report on Rapid Decompressions setting the groundwork for both further research in the areas of decompression as well as for our work for the summer. Diagnosing the timing of the venting process of our pressure vessel was the majority of my research. The first step was to establish that our compressed air tank vented predictably according to Haber and Clamann data. A hinged, aluminum flap was used to seal off the tank in order to pressurize the tank to 7.5psi which is the typical differential pressure for a commercial aircraft in flight. When the flap was released, it triggered an optical sensor, which in turn triggered an oscilloscope to record data from a pressure transducer mounted on the side of the tank. Data was analyzed from four different sized holes with different placements relative to the tank and the pressure transducer. The results from the trials were surprisingly repeatable, and as suggested by Haber and Clamann, could be corrected with a small orifice constant. We noticed a trend where the smaller holes would not vent as accurately as the larger holes and concluded that the smaller holes were more susceptible to airflow dynamics and were less predictable by the Haber and Clamann equations.

The next project was to determine what we called the delay time – the time that elapsed between when the flap opened and the pressure inside the tank would vent. We deemed this important, as this would directly influence how ast cabin pressure could be vented out of an aircraft in the event of an internal explosion. To extract relevant data out of the very noisy data curve we plotted a second order decay curve through the data and determined the intersection between it and the previous, constant pressure signal. Using this intersection point and a time marker, which indicated initial flap movement, we could determine the delay time, which was on the order of 5.7 ms for a 1.47-inch diameter hole in our tank.

The final step was to build a second tank that was closer to the scale dimensions of a 747 aircraft. We used a 5-foot section of 8-inch diameter PVC pipe, which had removable end caps allowing us to access the inside. Using this new tank, we ran tests to confirm that the tank would vent as predicted by Haber and Clamann data. The results were in good agreement with Haber and Clamann data so we continued on and simulated scaled down aircraft windows. Our tests encompassed a variety of placements and numbers of windows, anywhere from one venting window, to the complete side of a plane. Our conclusion was that a number of smaller holes would vent at the same rate as a single, larger hole of equal area.

Most importantly our research has laid the groundwork for more testing in the area of the timing of the onboard explosion, to see if a aircraft could indeed be vented quickly enough in the event of an explosion to prevent massive structural failure.