Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD.


A project under the management of Air Force Research Laboratory has begun development of a six degree of freedom model for use in hypersonic vehicle development and application. One area of interest is the perturbation of vehicle behavior based on atmospheric fluctuations – how the performance of the vehicle changes with respect to “hot”, “cold” and standard day conditions. The method developed to fill this need uses real-world data from the Global Forecast System to create a “hot” and “cold” day dataset to compare with the standard day model. The key parameter is atmospheric density, a value calculated over a series of given points around the globe for any given dataset on a given day, and which directly impacts the lift and drag acting on the hypersonic vehicle, primarily over its re-entry trajectory. The results from simulations demonstrate trends that contradict expectation – the colder day cases result in a further longitude being achieved on average and yet experience a higher average drag. The optimal solution fluctuated 5-10% of the total range, or approximately 1.5 degrees in longitude, with matching orders of magnitude in fluctuations in the force of drag acting on the vehicle. General trends are stable – the two key trends with respect to longitude and drag remain true overall – the “cold” day cases have both the largest average drag and the longest distance traveled. Some analysis of the results proves these are reasonable results. These results enhance the strategic picture, but more test cases and analysis must be done before this model is ready for use.

AFIT Designator


DTIC Accession Number