THE FUEL ON BOARD TEAMMELISSA DAVIS

ROBERT FULLI NGMICHAEL DREHER-BRYRD

MAT THEW PLOURDEMENTOR - DR . ROBERT L . ASH

Fuel on Board a General Aviation Aircraft

Outline

Background Problem definitionCompletion of the project

Float Capacitance LabVIEW & Data acquisition Testing & Results

ConclusionWebsite/Gantt chartWorks cited

http://www.iaopa.eu/contentServlet/iaopa-news-july-2014

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 rollAccelerometers Deionized waterWiring and installing the prototypesMeasuring 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

Measured Voltage Values for Potentiometer Float System

Run Block Block Run Volume (gallon)

Pitch (Degree)

Roll (degree)

Pot 1 (Voltage)

Pot 2 (Voltage)

Pot 3 (Voltage)

Pot 4 (Voltage)

3 Block 1 1 1 1 -30 30 3.35824 3.41613 3.48689 3.51263 1 Block 1 1 2 1 -30 -30 3.36338 3.42128 3.49204 3.51649 2 Block 1 1 3 1 30 -30 3.4097 3.42128 3.44701 3.50877 4 Block 1 1 4 1 30 30 3.35695 3.37496 3.44315 3.51134 6 Block 1 2 5 3 30 -30 3.43286 3.43286 3.46502 3.47274 8 Block 1 2 6 3 30 30 3.39426 3.39297 3.50748 3.52163 5 Block 1 2 7 3 -30 -30 3.41871 3.43028 3.46631 3.46245 7 Block 1 2 8 3 -30 30 3.36724 3.38268 3.49976 3.49847

14 Block 2 3 9 3 30 -30 3.41356 3.41099 3.44572 3.45859 13 Block 2 3 10 3 -30 -30 3.41227 3.42257 3.46374 3.45859 16 Block 2 3 11 3 30 30 3.38268 3.37754 3.49333 3.51134 15 Block 2 3 12 3 -30 30 3.3621 3.37882 3.4959 3.4959 12 Block 2 4 13 1 30 30 3.35695 3.37496 3.44701 3.51134 10 Block 2 4 14 1 30 -30 3.40069 3.41356 3.438 3.4959

9 Block 2 4 15 1 -30 -30 3.35438 3.41742 3.44058 3.46245 11 Block 2 4 16 1 -30 30 3.35824 3.41613 3.48947 3.51263

Max 3.43286 3.43286 3.50748 3.52163

Min 3.35438 3.37496 3.438 3.45859

Capacitive Tube Results

Fluid Height (cm)

Angle of Roll

(degrees)

Right Capacitive Tube Voltage

(V)

Left Capacitive Tube Voltage

(V) 0 0 1.482407 1.756448 1 0 1.531297 1.446383 2 0 1.352463 1.371762 3 0 1.550596 1.333164 4 0 1.518431 1.29714 5 0 1.396207 1.243104 6 0 1.264976 1.187781 7 0 1.189068 1.136318 8 0 1.071989 1.06813 9 0 0.170099 0.253726

10 0 0.126355 0.194544 11 0 0.087758 0.136648 12 0 0.064599 0.10577 13 0 0.054307 0.087758

Testing - Dynamic

Dynamic testing scheduled for December 6, 2014The testing will determine the accuracy of the two

prototypesThe 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.

http://sine.ni.com/gallery/app/ui/page?nodeId=212383&mTitle=NI%20USB-6001&mGallery=set_usb-6001_2_3

Front Panel and Block Diagram

Discussion

System Accuracy Dynamic testing to be completed December 6, 2014. 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).  2013 General Aviation Statistical Databook & 2014 Industry Outlook.  [Online].  Availible: http://www.gama.aero/files/2013_GAMA_Databook-LowRes-02192014.pdf[2]  Joseph E Burnside, “Fuel Totalizers: EI, JPI are top values”, The Aviation Consumer, Vol. 38, pp. 16-20, Mar. 2008. [3]  National Transportation Safety Board (2012, Oct.).  Review of US Civil Aviation Accidents - Calendar Year 2010.  [Online].  Available: http://www.ntsb.gov/doclib/reports/2012/ARA1201.pdf[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 13-22.[6]  Li, Guohua, and Susan P. Baker. "Correlates of pilot fatality in general aviation crashes." Aviation,   space, and environmental medicine 70.4 (1999): 305-309.