Category Archives: Uncategorized

Aircraft ECS for HVAC Students

On 11 Oct 2018, I was asked to provide an Aircraft Environmental Control System (ECS) primer for Mechanical Engineering HVAC students.

The lecture notes are available at: ECS-Aircraft


Articulated 4 Bar Mount Design

In this note, I will design an articulated 4 bar mount for a radar system using CATIA. The system needs to be designed and built rapidly for a VIP demonstration. Here’s the design:

First, the design requirements and needs:

  • Precise pointing requirements from nadir (straight down) to horizontal.
  • Mount on a boom lift / cherry-picker bucket
  • Separate two antennas of 30 pounds and 10 pounds by at least 2 meters with less than 1 deg of twist.
  • Designed, sourced, and built within a tight schedule

The articulated arm as designed by CATIA met the design goals with a commonly available actuator. The use of a CAD model allowed for tuning of the geometry and resulting kinematics.

Using the gearing ratio between the actuator and the output angle, conservation of power, and the measured actuator dynamics, I was able to analyze, simulate, and tune the dynamic/transient dynamics of motion of the system. This analysis allowed for a truly coupled actuator/mechanism design and ensured that my design remained feasible across the entire operational envelope.

Design drawings were created to construct the actuation arm.

The as-constructed articulated arm met the design requirements and when mounted on a boom-lift was successfully was used for a data collection experiment.

This articulated arm mechanism’s development shows the power of CAD with CATIA for rapid support of R&D projects. I was pleased.

Aerospace Structures Course

Aerospace Structures (AEM 341) is a core aerospace engineering course for the study of methods of analyzing advanced beam and stressed skin structures typical of aerospace vehicles. Dr. O’Neill taught this course in the Spring of 2018.Book: Introduction to Aerospace Structural Analysis, Allen & Haisler, Wiley. ISBN 0-471-88839-7 (Book Review)

Goals: By the end of the course, students should be able to:

  • Understand structural terminology, nomenclature, and aerospace structural elements.
  • Demonstrate basic static and accelerated loads concepts and estimates.
  • Determine principle stresses and principle directions
  • Demonstrate structural analysis of advanced beams and cells in bending and torsion
  • Demonstrate analysis of shear and shear flow
  • Analyze, design and test an aerospace structure as a term project
  • Fluently converse with loads and stress teams in a design setting

Example Lectures:

Course Evaluation: The student course evaluation is at: 18-AEM341-AerospaceStructures. I appreciate the kind words.

  • His notes are extremely clear, and he very effectively communicates the material. He’s far more concerned about us understanding the material than anything else.
  • Helped me regain my hope and enthusiasm for aerospace

XOR Checksum

Recently, I have been working with embedded systems for UAS applications. One of the systems requires commands be validated with an XOR checksum. Rather than doing this by hand, I made a small simple Windows app (download here).Nothing fancy.

Southern Museum of Flight: 2018 Visit

On 4 May 2018, my Aircraft Systems class (and guests) visited the Southern Museum of Flight in Birmingham, AL. Thanks to the museum director Dr. Brian Barsanti for the guided tour. The highlight of the trip was a hands-on visit of a D-21 recon drone under restoration.

A student asked me what I look for at museums. This is quite an excellent question. The truth is that I’ve been around almost all of the aircraft previously. I’m not looking at the aircraft as a famous name but as an interaction…. an aircraft system. Can I figure out the “why” and “how”?

For the 2016 visit, click on

More photos are given below

Continue reading

Rewinged SPA

Thank you to Adam Benabbou and Sean Sawaya for designing and constructing a new wing for the SPA aircraft. This wing uses the SD7062 airfoil with a balsa and spruce wing structure covered with Monokote. I am looking forward to a series of interesting missions with this aircraft-wing combination.


Super Guppy Flyover

On 2 April 2018, NASA’s Supper Guppy flew over Tuscaloosa. Can you spot it?

Post Tornado Damage Assessment at Jacksonville State University

On 19 March 2018, a tornado hit Jacksonville State University’s campus. The tornado caused widespread damage across the entire campus and the surrounding neighborhoods. The tornado was a direct hit through the quad, library, and almost all major buildings.

The Remote Sensing Center was asked to provide post tornado damage assessment of the campus buildings. We (Tim Leopard, Chris R. Simpson, and I) flew a series of flights over the campus. We wish JSU the best; we hope these helped.

The full list of videos are below:

JSU Mathews Coliseum:
JSU West Quad, Dixon, Crow:
JSU Crow, Patterson, Logan, Sparkman, Williams, Mason, International, Ayers:
JSU Quad Area & Closeups:
JSU College Apts:
JSU Library:
JSU McGee, Martin, Library:
JSU McGee, Martin:
JSU McGee:
JSU McGee, Martin:
JSU McGee, Martin (rapid descent for traffic avoidance):
JSU Softball and tornado track flyby:
JSU Honors House 2:
JSU Honors House:
JSU Stone Center:
JSU Stone Center 2:
JSU Brewer Hall, Merrill Hall:
JSU Merrill East Roof:
JSU Merrill (Medium altitude circles):
JSU Library “Wind-Tunnel Gap”:
JSU Wallace Hall, ROTC tower, & High Altitude East Campus (E-W lines):
JSU Rowe Hall:
JSU Rowe Hall, High altitude East Campus (N-S flight lines):

CATIA on Windows 7

I own a personal license of CATIA v5. A recent Windows 7 update broke CATIA. Here’s how I fixed it:

  • Open regedit
  • Create “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\KeyExchangeAlgorithms\Diffie-Hellman”
  • New DWORD Value.
  • DWORD “ClientMinKeyBitLength”
  • Right-click Modify ClientMinKeyBitLength
  • Value “00000200” (Hex value)

[Update Feb 2019]

On Windows 10 machines, the default TLS/Schannel cipher is not enabled. When running “DSCheckLS.exe” the license server status will be “NOT RUNNING”.

To fix this, you will need to enable a specific cipher. In an administrator’s powershell, type: Enable-TlsCipherSuite -Name “TLS_DHE_DSS_WITH_AES_128_CBC_SHA”

This is not at all obvious.

Surveying Guest Lecture

The Civil Engineering CE 260 “Surveying” instructor for the Fall of 2017 asked me to give a guest lecture and flight demonstration of UAVs for civil engineering applications. The class began with a short lecture (CE260-UAV) and then transitioned to Bryce Lawn for a demonstration flight over the University of Alabama’s old chapel building. My laboratory took the photos and created a 3D reconstruction of the building suitable for civil engineering analysis.

We concluded with an aerial class photo.

Thank you to the CE 260 class and the Civil Engineering department, especially Profs. Graettinger and Stogner.

For reference, the full raw flight video is here. The careful viewer should note that this flight was conducted in accordance with FAA regulations and University of Alabama requirements. Please don’t replicate this flight without first talking to UA compliance, UA Grounds, and the Tuscaloosa ATC tower.