Theses and Dissertations

Issuing Body

Mississippi State University


Lacy, Thomas E. Jr.

Committee Member

Olsen, Gregory

Committee Member

Newman, James C., Jr.

Committee Member

Prabhu, Raj

Committee Member

Liu, Yucheng

Date of Degree


Document Type

Dissertation - Open Access


Aerospace Engineering

Degree Name

Doctor of Philosophy (Ph.D)


James Worth Bagley College of Engineering


Department of Aerospace Engineering


Unmanned aircraft systems (UASs) pose a potential threat to general aviation/commercial aircraft as UASs are increasingly incorporated into the National Airspace System. This overarching research is aimed at addressing the severity of a UAS mid-air collision with another aircraft. This study is primarily focused on the development of a finite element (FE) model of a ~4 lb fixed-wing UAS (FW-UAS) which will be used to evaluate the severity of small UAS mid-air collisions to manned aircraft. A series of impact tests were performed at the University of Dayton Research Institute - Impact Physics Lab, to study the impact behavior of the high-density components of the FW-UAS (i.e., motor, and battery). For each of the tests, a simulation was set up with the same initial conditions, and boundary conditions as the physical test and the same output parameters were correlated with the test results. A series of numerical stability checks were also performed using the validated FW-UAS FE model to ensure the stability of the explicit dynamic procedures. Simulated impacts between the FW-UAS FE model and targets (deformable flat plate, rigid flat plate, and rigid knife-edge) were performed as stability checks. The FW-UAS FE model developed in this work facilitated the evaluation of the severity of FW-UAS mid-air collision to commercial and business jet airframes performed at and in conjunction with National Institute for Aviation Research. A series of worst-case scenarios involving impacts between the FW-UAS and commercial narrow-body transport and business jet airframes were simulated. For each simulated impact, an impact severity index value was assigned to characterize the relative threat to a given aircraft. In addition, a UAS frangibility study was performed to assess key UAS design features that result in reduced damage to target air vehicles. A “pusher” engine configuration was modeled where the high-density motor is located aft of the UAS’s forward fuselage. Positioning the high-density motor in the aft fuselage played an important role in reducing the impact damage severity.