Data Driven Analysis of Samara Seed Kinematics and Dynamics

Author

Shashwat Sparsh, California Polytechnic State University, San Luis ObispoFollow

Available at: https://digitalcommons.calpoly.edu/theses/3140

Date of Award

6-2025

Degree Name

MS in Aerospace Engineering

Department/Program

Aerospace Engineering

College

College of Engineering

Advisor

Nandeesh Hiremath

Advisor Department

Aerospace Engineering

Advisor College

College of Engineering

Abstract

Samara Seeds are a class of fruit most famously belonging to the Acer species and are characterized by their single-bladed geometry and their auto-rotation response during descent. This steady-state auto-rotation response is the subject of aerodynamic analysis which aim to quantify the performance. The period prior to the beginning of steady-state auto-rotation is classified as the transition regime and has not been the subject of intense scrutiny.

This thesis employs a data-driven approach to analyzing the kinematic and dynamic response of these seeds during both the transition and auto-rotation stages of flight to quantify the performance with respect to the time it takes to transition. The descent of 100 Tipuana Tipu seeds are captured using high-speed imaging and the trajectories are extracted using Python. The kinematics and dynamics are computed using existing models in literature to characterize the aerodynamic performance. The maximum reduction in descent velocity and corresponding highest specific thrust occurs during the transition regime as the auto-rotation begins. The dynamic response during the steady-state regime of these seeds illustrates greater lift performance and similar drag performance compared to Acer seeds but poor correlation to the transition regime duration. As current aerodynamic models fall short of quantitatively characterizing the transition regime and there are no apparent correlations between the transition time and the kinematic and dynamic performance, a novel statistical method relates the transition time to the morphology of the samara. This model suggests the blade area and aspect-ratio are the two primary driving factors in influencing transition time with the lower values corresponding to faster transitions. The mass and chord of the samaras are identified as secondary factors of influence of the transition time.