Principles of Rocketry

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Principles of Rocketry
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Our Water Rockets

• Instead of hot gases creating pressure, we use a
  bike pump and store pressure

Action Expelling water from engine bottle.
(water is forced down)
Reaction Water resisting against rocket body.
(Rocket is forced up)
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Water Rockets Work Like Real Rockets
DRAW THE ROCKET AND WRITE EVERYTHING DOWN
Pascals Principle
Reaction Bottle forced up by water being
expelled down
High Air pressure is transmitted equally in all
directions and parts of the fluid.
Action
Water forced out and down by air pressure
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Other factors that make the Water Bottle Rocket
Fly
Compressed Air Water
Dont WRITE This
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How Newton's Laws Affect Our Rockets
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• Newton's First Law

The pressure inside the rocket must overcome the
INERTIA of the rockets weight to launch. If the
rocket has too much water, it will have too much
weight/INERTIA.
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Newton's Second Law

• This is why you need just the right mass and
  force to achieve a good acceleration

80psi is perfect for 275-350g
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Newton's Third Law
DONT WRITE WHATS IN YELLOW

• When you pull the pin, that area of High Air
  Pressure in the top of your rocket engine is
  going to force, throw, hurl, spew that "massive"
  water out the bottom of your rocket at a great
  speed. The water and air is pushing down (action
  force), so your rocket must go up (reaction
  force).

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Stability During Flight
The orientation of fins and distribution of mass
help make the rocket stable.
Center of Gravity
Center of Pressure
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Stability During Flight.
Think about a dart.
DONT WRITE THIS DOWN
Fins or feathers in the rear act like wind veins
and trail behind
Heavy mass in front carries the momentum
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Newton's 3 Laws Explains Everything
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• Newton's 3 Laws of Motion
• 1 An object will stay at rest unless a force
  acts upon it.
• 2 Force Mass x Acceleration
• 3 For every action there is an equal and
  opposite reaction.

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Center of Gravity
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The next drawing indicates how the fin should
look once folded. Mark straight lines on
the bottle by putting the bottle in the door
frame or a right angle and trace a line on the
bottle with a marker. Use these lines as guides
to place the fins on the bottles. 
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• Title Rocket Lab
• Purpose
• Hypothesis
• Procedure
• Drawing Rocket Design Rough Draft (label all
  parts, give dimensions, shape, etc.)