Gerald Slusher

The engine and exhaust system vibration and exhaust gas and metal temperature levels were determined for flight and ground conditions on several single-engine aircraft for purposes of establishing exhaust system and heat exchanger design and test criteria. The temperature data were presented as a function of engine compression ration and the vibration data were plotted against engine horsepower to foster the general utilization of the information.

Method of data presentation permits the estimation of exhaust gas temperatures for horizontally reciprocating engines. Temperature measurements indicated uneven heating of the muffler outer wall (heat exchanger surface) reflecting uneven flow of the exhaust gases through and around the baffles and diffusers probably producing thermal stresses and contributing to failure. Baffles and diffusers within the mufflers of engines with compression ratios of 8.5:l of higher are exposed to exhaust gas temperature levels under which standard construction materials (AISI 321 and AISI 347 stainless steels) become marginal with respect to high temperature oxidation, carbonization, and attack by lead compounds.

Vibration of general aviation aircraft engines was noted to increase with increased power rating and reached maximum intensities under takeoff conditions. The acceleration level of mufflers on engines of high power compared favorably with the MIL-STD-810A Vibration Test Specification for equipment mounted directly on aircraft engines. Recommended procedure for development of new exhaust system designs involved random vibration testing under operating thermal conditions.

D. Gross, J.J. Loftus, T.G. Lee, V.E. Gray

Measurements are reported of the smoke produced during both flaming and smoldering exposures on 141 aircraft interior materials. Smoke is reported in terms of specific optical density, dimensionless attenuation coefficient which defines the photometric obscuration produced by a quantity of smoke accumulated from a specimen of given thickness and unit surface area within a chamber of unit volume. A very wide range in the maximum specific optical density was observed. For the majority of materials, more smoke was produced during the flaming exposure test. However, certain materials produced significantly more smoke in the absence of open flaming.

During the smoke chamber tests, indications of the maximum concentration: of CO, Hct, HCN and other selected potentially toxic combustion products were obtained using commercial colorimetric detector tubes. A study was made of the operation, accuracy and limitations of the detector tubes used. Measurements of the concentrations of HC were also made using specific ion electrode techniques.

The elevated temperature thermal degradation of selected materials was studied in a number of ways including thermogravimetry and differential scanning calorimetry.

Qualilative identification of the major components of the original test materials was accomplished primarily by infrared absorption spectrophotometry.

Of the materials tested, a number were found to possess good'heat stability properties, and did not generate large quantities of smoke or high concentrations of the combustion products selected for analysis.

D. Gross, J.J. Loftus, T.G. Lee, V.E. Gray

Measurement are reported of the smoke produced during both flaming and smoldering exposures on 141 aircraft interior materials. Smoke is reported in terms of specific optical density, a dimensionless attenuation coefficient which defines the photometric obscuration produced by a quantity of smoke accumulated from a specimen of given thickness and unit surface area within a chamber of unit volume. A very wide range in the maximum specific optical density was observed. For the majority of materials, more smoke was produced during the flaming exposure test. However, certain materials produced significantly more smoke in the absence of open flaming.

R.J. Elling

This study presents an analytical comparison of design approaches to incorporate an integral airborne cabin fire-suppressant system into the Lockheed L-1011 commercial transport airplane. The purpose of this study is to determine feasibility, establish weight penalties, and evaluate the actual requirements for incorporating such a system in response to customer request.

Two independent systems were evaluated: (1)Self contained modular unit, total flooding type fire suppressant system. (2)Ground-supplied, central distribution system.

Both systems are based on the dispensing of Freon as the fire suppressant agent from overhead dispersal type heads are uniformly distributed throughout the passenger cabin and associated critical compartments.

Neither a modular nor a centralized system, of the size and complexity required for the L-1011, has been operationally developed to date. Variable contingencies involved in the dynamic control of cabin air-flow versus agent concentrations maintained within human acceptable tolerances clearly indicates that continued research must be pursued to validate the performance of an acceptable system applicable to airplane fire conditions. It is recommended that an independent, readily installed/removable, fire protection system be developed to provide airplane protection during manufacture, maintenance, overhaul and unattended periods. This type system does not add airborne weight penalty to the airplane and provides installation flexibility with unlimited amount of agent supply (service carts).

S.R.M. Sinclair

This research has been concerned with a theoretical description of shock wave structure in gaseous mixtures when diffusive effects are important.