In the Spring of 2016 at the University of Alabama, I taught a brand new course titled Aircraft Systems under the course number AEM 617. Topics under consideration included:

• Nomenclature (Sample Notes: Lesson01-Introduction)
• Standard and Non-standard Atmospheres (e.g. Moist Air Density)
• Airspeed (Flight Data Computer Calculations)
• Vacuum Systems
• v-n Diagrams including gust loading
• Basic 4 bar mechanisms (e.g. slat & flap extensions) and Freudenstein Equations
• FAR 23 (14CFR23)
• FAR 25(14CFR25)
• Cockpit Layouts
• Flight Control Systems including equations of motion, gear ratio
• Aircraft Hardware (e.g. AN bolts, rivets, etc.)
• Hinge Moments (Guest Lecture)
• Nonlinear Systems Phase Plane Analysis
• Hydraulic Systems including Actuators, PCU (Power Control Units),
• Fuel Systems including Inerting Systems and Refueling
• Pressurization Systems (Guest Lecture)
• Test Flight Systems and Instrumentation (Guest Lecture)
• Communication and Navigation
• Environmental Control Systems (ECS)
• Emergency Systems
• Survivability
• Inertial Navigation Systems including World Reference Frames, and Strapdown Equations
• OBOGS (Onboard Oxygen Generating System) (Guest Lecture)
• Kalman Filters
• Electrical Systems and Wiring  (Guest Lecture)
• Morphing Wings (Guest Lecture)
• Software Development and Modular Avionics Bus
• A brief description of IEEE 754 floating point numbers
• Spacecraft Attitude (Guest Lecture)
• Propulsion (Guest Lecture)
• Multi-Engine Vmc

The notes contain numerous hand drawn images of systems and references to many books.

Detailed Aircraft Systems of Particular Aircraft were analyzed through flight manuals, NTSB accident reports, AIAA case-studies, and expert guest lectures.

• Cessna 170 & 310
• Gossamer Condor
• VTOL: VJ101 and VAK191B
• X15
• WW2 Dam Busters (system development case study)
• THAAD
• DHC-7 (aka. EO-5C / RC-7B)
• A behind-the-scenes guided tour of the Southern Museum of Flight in Birmingham by two (2) PhDs in History and Engineering.

The course also included a set of lectures titled “Failure Fridays” which investigated aircraft incidents and accidents by tracking the failure points and symptoms with a special emphasis on systems. These included:

• Cessna 182 Fuel Contamination
• Alaska 261
• A320 Fly By Wire
• Boeing 737 Rudder Actuator
• TWA 800
• Diesel Bug
• Advisory Circulars (AC)
• Patriot Missile
• Ariane 5
• The largest non-nuclear explosion known to man. (Not aerospace, but still an impressive and covertly intentional systems failure!)

This course was particularly interesting; as the instructor, I learned a great deal about many topics. I had to work hard to stay ahead of the students. The students gave one of the best ratings that I have ever received. One student said:

The course was very interesting and likely one of the most valuable classes I have had in college. Rather than sticking strictly to theory as most of the Aerospace curriculum does, this class covers details about the what, why, and how for a wide range of
systems that will be particularly useful in any aerospace career.

Another student said:

This course provided me with an otherwise unobtainable insight into the real world of engineering systems, something not talked
about in other courses. This class is great for the industry engineer.

Not every comment was so positive. One student mentioned that this course required several prerequisites and that “newly transferred” students would find the course “difficult”.

More information and the full course notes are available by contacting Charles O’Neill.

This summer, my lab in conjunction with Dr. Branam developed an aircraft for testing a prototype flight control system. The aircraft flies beautifully for a rudder-elevator control system. Low power and a large efficient wing allows for exceptional performance at the design weight. As a design decision, the rudder-dihedral roll control is sufficient for the mission purposes.

SPA aircraft

The aircraft specifications are:

• Wing span: 8 ft
• Powerplant: OS 3815-1000 with 5000 mAh 3S LiPo
• Airfoil: SD7062
• Differential spoilers (marginal for roll control)

SPA aircraft

Thanks to the following engineers and designers:

• Josh Richards (chief design engineer, air-to-air video pilot)
• Christopher D. Simpson (chief systems engineer)
• Christopher R. Simpson
• Reid Ruggles
• Abraham Ortiz
• Alex West
• Griffin Uthe
• David Maulick
• Liz Suttles

Counterfeit Futaba servos exist. My students and I managed to purchase a few for a recent aircraft project. These were purchased off of Amazon. We now call these “Faketaba” servos.

Question: How many ways can you tell that the following servo is a counterfeit Futaba S3003 servo?

Answer:

• The servo performance is significantly worse than a genuine servo. In fact, I (Charles O’Neill) initially discovered that these servos were not genuine after performing a systems check of installed servos. The return to zero had a hysteresis of about several millimeters at the servo horn, which gave a surface deflection static hysteresis “zero” of about +-10 degrees. This was completely unacceptable for our application. These were immediately removed and replaced.
• The Futaba logo and font is not correct. As a typography enthusiast, I spotted the slight imperfections in the name sticker.
• Gear noise is sigificantly higher for these fake servos. The gear geometry and tooth count are different from actual Futaba servos.
• In addition to the gear noise, the output shaft tolerance created an issue with the bearing surfaces. Also, the spline shaft poorly fit the servo horns. The servo horns themselves were significantly thicker than genuine horns.
• After installation, I went back and found the box that the servos were shipped in. This is obviously not a genuine Futaba box.
• I opened one servo to investigate the counterfeit quality. The grommet was not sealed correctly, a mistake that the Japanese Futaba company would never allow. The motor is only press fit into the servo case; this is a sneaky possible failure point. The servo case is geometrically different from an actual case.

• The mounting holes are opened at the end. Actual Futaba S3003 servos are closed.

One additional point of discussion, the cost for these counterfeits was similar to actual genuine servos. My students learned a difficult lesson in trust.

My students are strongly encouraged to demonstrate their capability through a web presence.

• Christopher D. Simpson (PhD student) http://www.cdsimpson.net/
• Chrisopher Ross Simpson (PhD student) https://simpsonaerospace.wordpress.com/
• Steve Pomroy (MS/PhD student) http://www.flightwriter.com/https://www.linkedin.com/in/stevepomroy
• Josh Richards (BSAE) https://www.youtube.com/watch?v=SWdLy5ZUDAM
• Easton Davis (BSAE) https://eastondavis.com/
• Daniel Stucki (BSAE) https://stuckidaniel.com/
• John Glidden (BSAE) https://john-glidden.com/

This is an informal group of UAV and RC aircraft pilots and designers who meet each Friday at 4pm to fly and learn to evaluate aircraft.

The group is also provides UAS training for FAA certification within Part 107. Contact croneill@eng.ua.edu for details.

This page exists to log my visits to the surviving Lockheed A-12 aircraft. Photos are in serial number order.

60-6925 in NYC: no photo

A12 60-6930 in Huntsville, AL

A12 60-6933 at the San Diego Air & Space Museum

A12 60-6937 in Birmingham, AL

A12 60-6938 in Mobile, AL

Today, we manipulate bits to resurrect a hobbled 15 year old GPS receiver. In the process, I learned about WAAS and s-records to successfully update a client’s  Magellan Sportrak GPS unit.

Continue reading →

Today, my MS student Mr. Christopher Simpson successfully defended his thesis:

CONTROL SURFACE HINGE MOMENT PREDICTION
USING COMPUTATIONAL FLUID
DYNAMICS

The work demonstrated several key concepts necessary for the use of CFD in rapid aircraft prototyping of aircraft control surfaces. The thesis evaluated both 2D and 3D geometries using NASA LaRC’s FUN3D computational fluid dynamics software.

Christopher also conducted unsteady and adjoint refined solutions.

The final version is available here.

University of Alabama AEM 617 students visit the Southern Museum of Flight’s A-12

Today, we get a behind the scenes visit of the Southern Museum of Flight in Birmingham, AL to discover the complexity of aircraft systems. In the process, my class of graduate students learned to see aircraft in a different light.

Special thanks to the museum director Dr. Brian Barsanti. My students received a rare treat, a guided tour with both a professor of history and a professor of aerospace engineering.

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Landing on Mars is a difficult engineering problem. A recent conceptual project demonstrated this reality through the atmospheric reentry profile. In other words, assuming that your spacecraft approaches Mars at 200 kilometers and 6.5 kilometers per seconds, what is the altitude-velocity profile during the reentry trip?

Complicating the situation is an observation that your vehicle’s aerodynamics strongly affect the profile. In particular, increasing the life decreases the observed g-load, but leads to atmospheric skip when the lift is not controlled.

A ballistic reentry vehicle should expect a maximum g-load above 10 in the 50 km altitude region. This conceptual analysis strongly suggests that manned reentry to Mars will require hypersonic aerodynamics generation of a lift over drag (L/D) ratio in the 0.5 range.