Paper Airplane Science

1
Paper Airplane Science

• MESA Workshop at JHU/APL
• August 2003
• Tom Milnes Tony Jackson

2
The Technical Team

• APL Strategic Systems Department
• Independent Evaluation of Submarine Launched
  Missiles
• Members
• Tom Milnes Guidance and Navigation Group
• B.S. Applied Mathematics, M.S. Electrical
  Engineering
• Tony Jackson Missile System Evaluation Group
• B.S. M.S. Electrical Engineering

3
AIAA Baltimore
Precollege Programs

• Support MESA Challenges and Workshops
• Maryland Engineering Challenges
• Paper Airplane and Electric Cargo Challenge
• High School Mentor Students
• Wright Flyer Simulation
• Wind Tunnel
• Civil Air Patrol
• Howard County Squadron Cadet Program
• Grants for K-12 Educators

4
K-12 Grant
Program

• 200 per teacher and 1000 per school for Math,
  Science, Technology, Engineering classroom
  projects
• 3 Easy Steps
• Join AIAA for Free as an Educator Associate
• Fill out one page request form
• Principal Approves
• After project completed send in 1 page feedback
  form

5
More AIAA Info

• AIAA
• Web Site http//www.aiaa.org
• AIAA Baltimore Section
• Web Site http//www.jhuapl/aiaabaltimore

Look for Precollege Programs
6
Paper Airplane Science

• Key Reference
• Paper Airplane Aerodynamics
• http//www.paperplane.org/paero.html
• Written by Ken Blackburn Guiness Record Holder
  for Paper Airplane Time of Flight

7
Paper Airplane as a Science Project

• Easy to Build But Hard to Perfect
• Paper is a fairly good project material
• Inexpensive
• Light
• Can be strengthened by folding
• Lots of Science!

8
Paper Airplane Challenge

• Three Throws
• Average of Two Best Throws for Distance (ft)
• Best Throw for Time of Flight (seconds)

9
Ideal Steady State Flight
Lift
Drag
Thrust
Constant Velocity No Rotation
Gravity
10
Launch
Lift
Motion
Thrust
Drag
Gravity
11
Glide
Lift
Motion
Drag
Gravity
12
Creating Lift - Angle of Attack
Simplest Method Turn a Surface into the flow of
Air
Angle of Attack - ?
13
Creating Lift - Angle of Attack
Simplest Method Turn a Surface into the Flow of
Air
Faster
Slower
Newtons 3rd Law For every action There is an
equal and opposite reaction
14
Creating Lift - Angle of Attack
Pitching Moment
Lift
L
Drag
H
Newtons 3rd Law For every action There is an
equal and opposite reaction
15
Bernoullis LawConservation of Energy
Directed Kinetic Energy
Gravitational Potential Energy
Random Kinetic Energy
(Per Volume)
Along a fluid streamline
16
Fluid Forces

• Dynamic Pressure Force Acts only if surface is
  perpendicular to flow
• Static Pressure Force Acts Perpendicular to All
  Surfaces
• Viscous Force Acts if there is a change in
  velocity perpendicular to the flow

v
l
17
Countering Pitching MomentUse of Elevator
Lift
CG
CP
Gravity
18
Lift/Drag Angle of Attack
Smaller L Larger D L/D Decreasing
? over critical
H
Design Point
L
? critical
Stall
Larger L,D Largest L/D
Lift/Drag, L/D
? larger
Larger L,D Larger L/D
Angle of Attack, ?
Small L,D L/Dgt1
? small
No Lift Small Drag
? 0
19
Creating Lift Camber
Camber - Curve Surface to Better Redirect Flow
Greater Redirection Of Flow
20
Creating Lift Custom Airfoil
Custom Airfoil Varying Thickness in addition to
Angle of Attack and Camber
Typical Airplane Foil
Is this Airfoil Necessary?
21
Viscosity - ?

• Highly viscous fluids have difficulty getting
  around objects at low speeds creating large drag
  due to high pressure in front and low pressure
  behind

22
Inertial Forces vs. Viscous Forces

• Reynolds Number
• Reynolds numbers of paper planes are similar to
  insects rather than airplanes
• Thin wings with very little camber are optimal to
  avoid viscous drag.
• Reynolds Number key for scale modeling!
• ¼ model must have 4x greater velocity to be
  similar

23
What Wing Shape?
Increased Area Increases Lift
Answer Short Length and Large Wingspan
24
The Ideal Situation
Large Lift
Residual Forward Motion (Thrust)
Small Drag
Gravity
Nature will conspire to upset the Ideal
Situation Want Airplane To Automatically
Return to it Stable Flight
25
Stable Flight

• Key to Stable Flight is the tendency of the
  airplane to turn into the relative air flow while
  keeping the the airplane right side up

26
Turning Into the Airflow Pitch Angle
Lift
Elevator Effect Cancels Unbalanced Gravity and
Lift Forces
Airflow
Drag
Gravity
27
Turning Into the Airflow Pitch Angle
Lift
Increased Angle of Attack
Airflow
Drag
Elevator Effect Is Less Than Lift Effect
Gravity
28
Turning Into the Airflow Pitch Angle
Decreased Angle of Attack
Lift
Drag
Airflow
Elevator Effect Is Greater than Lift Effect
Gravity
29
Stability Rule CP aft of CG
CG Center of Gravity
CP Center of Pressure
Airflow
Balance Point
Silhouette Balance Point
30
Turning Into Airflow Rudder for Yaw Angle
31
Turning Into Airflow Dihedral for Roll and Yaw
Angles
32
Dive Correction Example
Zero Airspeed Initially
Gravity
33
Dive Correction Example
Gravity
Motion
34
Dive Correction Example
Drag
Lift
Gravity
Motion
35
Dive Correction Example
Drag
Lift
Gravity
Motion
36
Dive Correction Example
Lift
Drag
Motion
Gravity
37
Dive Correction Example
Lift
Drag
Motion
Gravity
38
Optimal Thrust for Time of Flight
Thrust
39
Optimal Thrust for Distance
?
Thrust
40
Trimming
All Aircraft Must be Trimmed for Optimum
Flight! Crisp Folds are a must! GOOD LUCK!