3. Review - Gliders
• Have No Powered
Thrust
• Typically have a
LONG wing span
• Usually very
LIGHT
• Built to Reduce
Drag
4. What can we Control on our
Gliders?
• Mass
• Placement of
wings for MAXIUM
LIFT
• Angle of Wing
• Aerodynamic to
REDUCE Drag
5. How Do We Control Lift?
• Bernoulli's Principle
• Angle of Wing
http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html
6. Bernoulli's Principle
• Bernoulli's Principle states - as the velocity (speed) of a fluid
(air) increases, the pressure exerted by that fluid (air) decreases.
Airplanes get a part of their lift by taking advantage of Bernoulli's
principle. Race cars employ Bernoulli's principle to keep their rear
wheels on the ground while traveling at high speeds.
• If wings were flat
– Air would travel from front of the wing - back of the wing
covering the same distance over the same time
• However - Wings are Curved on top
– So the air takes longer to travel over the top of wing to catch up
with the air moving under the wing
• Faster air on Top / Slower air on Bottom
7. Bernoulli's Principle
• Bernoulli's Principle
– Air on top is moving so FAST it can NOT add
pressure (LESS / LOW AIR Pressure)
– Air on bottom is moving SLOWER so it adds
pressure (MORE / HIGH Pressure)
• Lower Pressure on TOP and
High Pressure on BOTTOM
creates LIFT
11. How do we Control Drag?
• Which is more
aerodynamic?
– A Hummer or a
NASC Car
12. How do we Control Drag?
• How about between
Tony Stewart and
Dale Earnhardt Jr.
• NASA wants to know
the subtle differences
13. Testing Drag
• NASA can use either
a Wind Tunnel or
Fluid Dynamic Lab to
understand the
aerodynamics of a
plane
– Wind tunnels use wind
to match “real time”
velocity and speed
– Fluid Dynamic Labs
use water moving at a
slow speeds
15. Shoe Box has to remain INTACT
Four (4) Sides and bottom
Can slit sides of box to insert wings
NO PROPELLERS – Nothing to add power or thrust
Can use any kind of material you want
(duck tape, news paper, yard sticks, etc)
And of Course – A Shoe Box
16. - Glide Slope Ratio
Distance / Height Thrown
- Aspect Ratio
Length of wing / Width of wing
- Higher the number the better the design
