Author Archives: co

1983 Photo

I recently found an old photo from 1983 of me next to a trike. Judging from the background hanger’s appearance, this is apparently the large north hanger at KELK.

Project: Electronic Directional Gyro

Electronic Directional Gyro
Charles O’Neill
2004

This project developed an one degree-of-freedom electronic aircraft directional
gyro (DG). The mechanical inertial gyro in a 1960’s vintage DG was removed
and replaced with an stepping motor driven by a micro controller connected to
an electronic rate gyro.

Directional Gyro Retrofit

The project document is available here

Boomerang Soccer Ball

Boomerang Soccer Ball
Charles O’Neill
2002

The goal is to determine possible soccer ball launch configurations that result in the ball returning to the launch site. A returning soccer ball is possible with the proper launch angle and velocity. A headwind is required except for the purely vertical case.

Trajectories with long free fall times are extremely sensitive to their initial conditions. These critical trajectories have outgoing and incoming paths that are vastly different.

Flow regimes and the resulting drag coefficients dominate the launch configuration. The transition to fully turbulent flow increases the required launch angle. Higher headwinds quicken the appearance of the turbulent region.

The document is available here

Project: Optimizing an Aircraft-Based Communications Platform

Optimization Applications: Aircraft-Based Communications Platform
Charles O’Neill
2004

Conceptually, a high endurance aircraft circles over a service area to provide high-bandwidth communication. The objective is to maximize endurance. The basic physical geometry is a conventional aircraft powered by a small fan-jet engine.

Aircraft Configuration Feasible Space

The project is available endure.pdf.

Project: Assembly Programming on the PIC16F876

Assembly Programming
on the PIC16F876
Charles O’Neill
2004

This project demonstrate: assembly timing, A/D conversions, A/D conversion rates,and RC circuit time constants on the PIC 16F876. The micro-controller is a 28 pin DIP PIC16F876 clocked at 20 MHz manufactured by Microchip. The PIC voltage input is +5 volts DC via a µA7805 dc/dc voltage regulator. The compiler is the CCS C compiler (v. 3.207) for 14 bit PIC chips.

The full project is available here.

Project: Cubic Spline Interpolation

Cubic Spline Interpolation 
Charles O’Neill
2002

A cubic spline routine was developed for unequally spaced sequential data points. Cubic spline theory is reviewed. A Visual Basic computer program in Excel was created to fit a spline to input data points. Three testcases are used to validate the routine. Conclusions regarding the cubic spline routine are made.

This project’s documentation is available at cubicspline.pdf.

The Excel code is available at cubicspline.xls.

For a numerical methods mini-project, this document has generated a surprising amount of email. There is apparently a demand for spline interpolation. Please visit my consulting page for support or more information.

Project Review: Airfoil Aerodynamics System Identification

Aerodynamic System Identification
Charles O’Neill
December 2004

This project investigates aerodynamic system identification. An airfoil produces time varying loads based on the current and past boundary conditions; this project seeks to identify the lift loads resulting from pitch motion.
The first part discusses some unsteady aerodynamic theory. The second part discusses the identification process. The final part discusses conclusions and observations.

A Box-Jenkins model successfully modeled the lowand moderate airfoil reduced frequencies, but was  troublesome at higher frequencies. Interestingly, the Theodorsen theory qualitatively matches the CFD results except above approximately a reduced frequency of unity. The moderate frequency lift deficiency predicted by Theodorsen was found in the CFD solution and the Box-Jenkins model. Interestingly, as the high frequencies were resolved, the system appears more distributed. The final Box-Jenkins model accurately predicted the forces resulting from a validation input signal.

Bode Frequency Response of Data and Box-Jenkins Model

The project document is at sifinal.pdf.

Project Review: Nonlinear Delta Wing Analysis and Control

Numerical Single-Degree-of-Freedom Analysis and Control of an 80
Degree Delta Wing with an Analytical Roll Moment Model
Charles O’Neill
December 2003

This project surveys nonlinear analysis and control methods for a specific two-degree-of-freedom analytical delta wing model. Linearization, phase plane analysis and existence theorems are used to describe the overall system behavior without solving the differential equations. A describing function is developed for the nonlinear system and favorably compares to the actual limit cycle amplitudes and frequencies. Linear pole placement and Ricatti control methods and nonlinear sliding mode and Lyapunov control laws are developed for stabilization and tracking.

Sliding Mode Control Schematic

See the full project at wingrock.pdf