John Marcy

A preliminary appraisal of the problem of frictional sparking i8gnition in aviation.

F. Edwards Ehlers

Method for computing a shock wave and also a free streamline dividing two regions of isoenergetic supersonic flow are explained with computed examples of both two-dimensional and axially-symmetric flows. The subroutines as coded in FORTRAN language for the IBM 7094 are listed and the procedures for their use are described.

Paul M. Rich

The performance of a standard flight recorder, mounted aft of the pressurized bulkhead in the tail section of an air carrier transport aircraft was compared with that of a recorder as presently installed during flight.

Flight tests were conducted in conjunction with the FAA-NASA project TAPER (Turbulent Air Pilot Environmental Research) utilizing the FAA's Boeing 720. Two flight recorders and associated accelerometers were mounted in the aircraft; one in the cabin area near the center of gravity and one in the tail of the aircraft outside the pressurized bulkhead. The two recorders were modified to record altitude and airspeed as obtained from an altitude/airspeed transducer located near the pitotstatic source. The standard airspeed and altitude channels were supplied by specially installed pitot-static lines running from the nose to the tail of the aircraft.

There was no difference between the recordi.ngs of the flight recorder located at the e.g. and the recording of an identical recorder located in the tail for the parameters of airspeed, altitude, and heading. However, there was a difference between the acceleration readings of these recorders. Although there was no difference between the altitude and airspeed obtained from the pitot and static lines and the altitude obtained via an altitude/airspeed transducer, the altitude/airspeed transducer proved more practical.

Don W. Conley

Information was obtained on the effectiveness of helicopter downwash and ground foam equipment in extending the escape time for aircraft occupants in a post-crash fire environment by burning five C-97 aircraft under similar conditions. Additional tests, not involving C-97 aircraft, were conducted relative to rescue path studies.

Test data indicated that helicopter downwash extended the escape time when fire existed solely on the upwind side of a C-97 fuselage, but the escape time when fire was on both sides or solely on the downwind side of the fuselage. It was also found that helicopter downwash provided a considerable reduction in the radiant heat and air temperature in a simulated rescue path.

For the standard fire condition used and the equipment employed, the ability of ground crews to extend the escape time was found to be dependent upon the preburn time and the fuselage integrity with respect to emergency doors open or closed. An escape time of 50 seconds was computed for C-97 with emergency doors open as compared to 138 seconds or a C-97 with emergency doors closed. Test results amplify the need for a quick arrival of extinguishing equipment and a capability for a quick “knockdown” and control of the fire.

E.K. Litchfield

Severe explosion hazards could result from a massive spill of non-hypergolic fuel and oxidizer of a missile propulsion system; this problem would be especially severe with the high-energy systems where one or both of the propellant components are cryogens. The sensitivity of two such systems, liquid hydrogen + solid oxygen + diluents and liquid oxygen + solid \hydrocarbon + diluents, has been investigated employing a projectile impact \to determine the shock required to detonate these mixtures. With no diluents, each explosive system is initiated by a shock stimulus of 1.0 to 2.5 kbar. The explosive yields are such that 1-lb cryogenic mixture is equivalent to 0.6 to 2.0 lb TNT. Sodium chloride, nitrogen, and methyl chloride had inert desensitizing effects upon the liquid hydrogen mixtures but did not reduce the explosive yield. Sodium chloride and nitrogen desensitized the liquid oxygen system; sodium chloride or water ,reduced the explosive yield. of this system.

"Large volumes of detonable, gaseous hydrogen-oxygen mixtures would result from a massive spill of liquid hydrogen-liquid oxygen. Inhibition of detonation initiation by dry powder particle additives was investigated. The powder additives produced insignificant inhibition in comparison to that produced by gaseous diluents.

Flammability limit determinations of four additional halogenated hydrocarbons are included in a discussion of the characteristics of 10 such compounds. Most of the compounds were flammable in oxygen atmospheres at temperatures below 2000 F; their combustion products included toxic halogens or halogen halides.