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