Document Type

Honors Thesis

Major

Mechanical Engineering

Advisor(s)

Wilhelm Friess

Committee Members

Seth Campbell, Andrew J. Goupee, Olivier Putzeys, Sharon S. Tisher

Graduation Year

May 2022

Publication Date

Spring 5-2022

Abstract

This summer, a lighter-than-air (LTA) drone was tested in Alaska to measure glacier bedrock fracture density and orientation. Five flights were made in low wind conditions, and the directional stability of the airship made it too challenging to control in flight to realistically acquire useful image sets. The directional stability of the airship, when compared to an actively stabilized consumer-grade quadcopter was inferior. Flight logs and GPS data from the GPS on the LTA drone were analyzed and a quantitative assessment of the observed instability was made. The yaw axis and pitch were analyzed, and the yaw axis instability was greater than the pitch axis instability. The source of this instability included the excessive sensitivity of the yaw thruster, and the inherent yaw instability of the blimp shape. An attempt was made to reduce the yaw instability by reducing the yaw motor size. The observed instability may have also resulted from external sources like wind gusts and the glacier microclimate. The analysis informed modifications of the LTA drone to make it more stable for glacier research, which were implemented and tested. The thrust output of the tail motor was reduced by 59%. This change was associated with a reduction in median heading variability of 47% between test flights before and after modification. The reduction was proven statistically significant at a 99% confidence interval. Also, recommendations for further modifications include the implementation of autonomous flight control and envelope optimization.

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