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The Electric Cargo Plane ChallengeAn Aeronautics Challenge for the
Middle and High School Classroom
Tom Milnes
JHU/APL & AIAA Baltimore Section
Paul Wiedorn
Wilde Lake HS & TEAM
AIAA Baltimore Section Support
• Major Supporter of Maryland MESA– Judges for National Competition and MESA Days– Members of National Competition Committee– Up, Up, and Away Workshop– Workshops on MESA Aerospace Challenges– Classroom Visits– Career Workshops at BEYA Event– Funding for Classroom Projects– RC Airplane Program Pilot
AIAA Support for K-12 Educators
• AIAA Grant Program– $200 per teacher, up to $1000 per school for K-12
Classroom projects related to Aerospace– Steps
• Join AIAA for Free as an Educator Associate– https://www.aiaa.org/content.cfm?pageid=208
• Submit Online Application– https://www.aiaa.org/content.cfm?pageid=216– Must conform to guidelines, Principal approval needed
» https://www.aiaa.org/content.cfm?pageid=244
Electric Powered Flight as a Learning Tool
• Topics for Learning– Newton’s Laws, Forces and Torques, Conservation of
Mass, Momentum, and Energy, DC Electronics, Dynamics, Kinematics, Propulsion, Energy Conversion, Aerodynamics, Gravity, Stability, Equilibrium, Drag, Lift, Friction
National Standards
• Science– Standard B - Physical Science
• Motions and Forces• Conservation of Energy and Increase in Disorder
– Standard E - Science and Technology• Identify a problem or design an opportunity• Propose designs and choose between alternative solutions. • Implement a proposed solution. • Evaluate the solution and its consequences. Communicate the
problem, process, and solution.
National Standards
• Technology– Design
• Standard 8. Students will develop an understanding of the attributes of design.
• Standard 9. Students will develop an understanding of engineering design.
• Standard 10. Students will develop an understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving.
– Abilities for a Technological World • Standard 11. Students will develop abilities to apply the design
process. – The Designed World
• Standard 18. Students will develop an understanding of and be able to select and use transportation technologies.
Why Tethered Flight?
• Radio Controlled Airplanes Can Be Problematic for School Use– Expensive Electromechanical Controls Needed– Large Airfield and Good Weather Needed
• Tethered Flight Solves These Problems
Tethered Flight Concept
• Constrained Flight Path - Can be done Indoors- Expensive RC Equipment not needed
PowerPole
Tether
PowerSupply
FlatSpeaker
Wire
Clear Packing Tape
Electric Cargo Challenge
• Part of the Maryland Engineering Challenges– Held at the Glenn L. Martin Maryland Aerospace Museum
• Saturday February 20, 2010
– Open to all Middle and High School Student
Electric Cargo Challenge
• Maryland Engineering Challenges Rules– http://www.thebmi.org/index.cfm/cID/630
• MESA Challenge Rules– http://www.jhuapl.edu/mesa/events/mesaday/
competition.asp
Electric Cargo Plane Challenge
• Must complete one lap of tethered flight with and without cargo about the power pole– Plane must be 8” off the ground at all times
• Scoring
MESA MEC
Oral 30 30
Written 55 20
Design 40 20 Performance 55 55 - Most Weight
50 - Next Most …30 30 x Cargo/Best Cargo
TOTAL 180 100
What You Get
MANDATORYKelvin Electronics 850647
3-6V, 17000 RPM, .26Ahttp://www.kelvin.com
$.79 each
OPTIONALKelvin Electronics 990175
$5.75 per set of 8
What’s Needed
• Power Pole - We recommend Kelvin 850747 - $175– http://www.kelvin.com– AIAA Educator Grant Can Be Used to Fund
• Power Supply – Model Train Variable DC Transformer
What’s Needed
• Wings - Pink or Blue Foam Board - Home Depot $12
• Fuselage - Basswood or Graphite Kite Stay
The Four Forces
Thrust Drag
Gravity
Lift
Out of Trim
Thrust
Weight
Lift
Drag
Rotation
Center of Pressure (1/4 to 1/3 from leading edge of wing)
Center of Gravity (“Balance Point” of Aircraft)
Rudder
Elevator
Trimmed
Lift
Drag
Thrust
Gravity
Center of Pressure (CP) should Coincide with Center of Gravity (CG)For Level Flight!! Use Rubber Bands to Achieve Adjustable Wings!
Where to Put Cargo
• Don’t Want to Change Trim of Airplane• Should Add Cargo Such that Center of Gravity
(“Balance Point”) Does not move– Aerodynamic and Gravity Forces remain aligned so
Airplane Remains Trimmed
Electrical Connections
handsetplug
10 feet minimum
3 feet maximum
fuselage
main wing
propeller
motor
+/- wire pair
clear tape
empennage
Electrical Connections
Green -Yellow +Black -Red +
(View from Bottom)
How is Lift Generated?
• Lift is generated when a solid object such as wing turns a moving flow downward– Newton’s Third Law
• For Every Action there is an Equal and Opposite Reaction• ACTION - Air (which has mass and velocity) is directed downward• REACTION - Wing moves upward
• The Bernoulli Effect is a Minor Component of Lift– About 1/10 of Total– Ignores Viscosity of Air
• Causes Air to “adhere” the surface of the wing - “Coanda Effect”• Turning of Air about Leading Edge - “Leading Edge Suction” is the
primary cause of Lift
Pressure on Airfoil
Leading Edge Suction
Best Airfoil?• Best Wing Redirects Air Downward Without Slowing it
Down.– To a point more redirection is better– After that point air will not remain “attached” to wing
• Lift decreases and Drag increases “Stall”
– Trick is to find optimum level of redirection• Angle of Attack
– Even a flat plate will produce lift
• Camber– Gentle curvature of wing
• Thickness along Camber– Blunt Leading Edge
– Tapered Trailing Edge
– Maximum Thickness 1/3 way back
Best Wing?
• Should I Copy a Jet Airliner Wing?– NO - Aerodynamically Similar If– Since density and viscosity are constant for air want the
product of Velocity and Length (vL) to be the same• Jet Aircraft are both Bigger and Faster - Performance Not The
Same• Birds and Insect Wings are a Better Match
• How Long Should the Wing Be?– Use maximum 3’ - Lift increases with area and L/D
increases as wing span increases
vL / is the same
“Turning In Problem”
WeightOf Tether
Greater Weight on Inner WheelProduces Greater Friction
Airplane Turns Inward
Practice, Practice
• Successful teams will have experience flying, adjusting, and repairing planes– Unlikely to do well if your plane hasn’t been tested with
power pole
• Teachers can use AIAA Grant Program to Obtain Power Pole and Power Supply