Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Marc D. Polanka, PhD.


The effects of atmospheric pressure and temperature variations on the performance of small internal combustion (IC) engines operating at altitudes significantly above sea level are not widely documented. Using an altitude chamber and fuel-injected twostroke engine, data were collected while varying air temperature along with pressure. The peak engine power was 4.1 kW at roughly sea level standard conditions and dropped to 3.5 kW at the standard conditions for an altitude of 1.5 km. At a combination of pressure and temperature corresponding to an altitude of 3 km, peak power fell further to 2.5 kW. The combined effects of standard atmospheric conditions showed pressure dominated temperature and resulted in around a 3.5% loss of power and brake mean effective pressure (BMEP) along with a 3% increase in brake specific fuel consumption (BSFC) per 300 m increase in altitude.

AFIT Designator


DTIC Accession Number