THE FUEL ON BOARD TEAM MELISSA DAVIS ROBERT FULLING MICHAEL DREHER-BRYRD MATTHEW PLOURDE MENTOR - DR. ROBERT L. ASH Fuel on Board a General Aviation Aircraft

Outline Background Problem definition Completion of the project  Float  Capacitance  LabVIEW & Data acquisition  Testing & Results Conclusion Website/Gantt chart Works cited

Background Fuel management is a long standing issue for General Aviation, as current fuel measurement systems are often inaccurate, so fuel management predominantly relies on the pilot’s records and calculations[3][4] In 2010, there were 36 accidents and 5 deaths caused by fuel mismanagement in GA aircraft [1][3]. The Federal Aviation Administration (FAA) requires general aviation aircraft to display zero after all usable fuel is gone [2][5]

Problem Statement/Purpose Current fuel measurement systems for GA aircraft are often inaccurate, and have been the cause of stressful flying situations for pilots, crashes, and even death. The purpose of the fuel on board project is to design an economical fuel measurement system for general aviation aircraft that will measure and display the mass of usable fuel inside a tank within ± 3% error.

Potentiometer Float System - Theory Four float arms, each connected to its own float, will be connected to potentiometers inside a single sender unit at the top of the tank. The potentiometers contain resistors and wiper arms. The resistance changes as the wiper moves across it, and can be measured. The resistance of each potentiometer will be measured, and all four will be averaged together to give an accurate measurement of fuel remaining.

Potentiometer Float System - Theory The float prototype consists of four potentiometers braced to a metal plate and housed by a pvc pipe cap. A toilet bowl wax gasket was added to the inside of the pvc cap to seal the cap to the metal plate to waterproof the electrical components. Our float design has four potentiometers attached to metal rods The rods are attached to a float that sits at the top of the fluid in the tank The potentiometers change their resistance when there is a change in the height of the rod due to fuel increase or decrease

Potentiometer Float System - Fabrication Coat hangar rods were used as the float arms, each connected to a foam float that rises and falls with fuel surface Each aluminum rod bent at 90 degrees, and was fastened to a potentiometer arm by a rigid coupling. The potentiometers were secured and protected in a PVC cap, with holes drilled in the side of the cap to allow the potentiometer arms to protrude into the tank

Potentiometer Float System - Wiring The float system was wired to the DAQ with 3 wires per potentiometer for 12 wires altogether The first two wires create a loop from the 5V current/Voltage source to the potentiometer and then from the potentiometer to a ground The DAQ provides both the current/Voltage source and the ground The final wire is connected to an analog input starting at AI0 and going to AI3

Capacitive Tube System - Fabrication Two capacitance tube’s per system Each tube will be made of an aluminum rod, an aluminum tube, and small lengths of polyethylene tubing Either air or fuel will act as the dielectric insulator, depending on how much fuel is in the tank, and will flow between the aluminum rod and tube. The change of capacitance between the two tubes will be measured and will ultimately be converted to fuel height

Capacitive Tube - Theory A capacitor behaves according to coulomb's law, made up of two metal plates (conductors) separated by a dielectric (insulator), and holds a charge depending on the dielectric. Every dielectric substance is given a permittivity constant to account for its chemical makeup and insulation ability As the fuel level changes, the capacitance will change

Capacitive Tube: Wiring Alternating Current is applied to a resistor- capacitor circuit. Voltages are measured with the DAQ before & after a resistor Current can be inferred, along with capacitance, fluid height, and fluid volume

Testing Apparatus A cooler with dimensions of 21X11X5.5 in to represent a fuel tank Wheel barrow base to allow for pitch and roll Accelerometers Deionized water Wiring and installing the prototypes Measuring the liquid that has left the tank

Testing - Static Static testing was done to develop a linear regression model. Floats: Voltage measurements were taken at 30°pitch 30°roll,30°pitch -30°roll,-30°pitch 30° roll, -30° pitch -30°roll and 0°pitch 0°roll at one gallon and three gallons. Capacitors: Voltage measurements were taken at zero, +30°, and -30° roll at height intervals of one centimeter.

Potentiometer Float Results

Capacitive Tube Results

Testing - Dynamic Dynamic testing scheduled for December 6, 2014 The testing will determine the accuracy of the two prototypes The testing tank will be mounted to a wheelbarrow, and subjected to various pitch, roll, sloshing, and turbulent conditions Volume of liquid displayed by each prototype will be compared to actual known fluid volumes

LabVIEW and Data Acquisition The DAQ card will read voltage from the potentiometers and the capacitance tubes The DAQ will send the voltage readings into LabVIEW LabVIEW will record the readings as the experiment progresses LabVIEW will act as the microcontroller, converting voltage into liquid height for each concept, and then output the volume of fuel as a display &mGallery=set_usb-6001_2_3

Front Panel and Block Diagram

Discussion System Accuracy  Dynamic testing to be completed December 6,  Accuracy yet to be determined. Concept Success  Static testing data validates theory behind both concept designs  A measured voltage drop across a potentiometer can be measured and correlated to fluid level  A measured voltage drop throughout the resistor-capacitor circuit can be correlated to fluid level

System Cost’s Capacitor tubes  $7.00 per tube Potentiometer Floats  $37.16 for complete prototype  Current potentiometer single float sending units run for around $100 minimum Costs for both systems  Microcontrollers and displays used in the system can be purchased for about $50.00

Conclusion From the static testing data, it can be concluded that the capacitive tube fuel measurement system and potentiometer float fuel measurement system prove our concepts. They record and display the amount of the fuel in the tank, however without the dynamic testing we are unable to calculate that accuracy of the displayed data Not only are these designs affordable, but if they are within the ± 3% error margin, they could reduce the GA aircraft crash rates and reduce pilot stress and workload.

Work Cited [1] General Aviation Manufacturers Association (2014) General Aviation Statistical Databook & 2014 Industry Outlook. [Online]. Availible: pdf [2] Joseph E Burnside, “Fuel Totalizers: EI, JPI are top values”, The Aviation Consumer, Vol. 38, pp , Mar [3] National Transportation Safety Board (2012, Oct.). Review of US Civil Aviation Accidents - Calendar Year [Online]. Available: [4] Norm Crabill, “Proposed Research Topics for General Aviation, Fuel-On- Board”, unpublished. [5] Aviation Maintenance Technician Handbook-Airframe, United States Department of Transportation, Federal Aviation Administration, Oklahoma City, OK, 2012, pp [6] Li, Guohua, and Susan P. Baker. "Correlates of pilot fatality in general aviation crashes." Aviation, space, and environmental medicine 70.4 (1999):