Making it Fly

Newton's three laws

I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
- - I call this one the "lazy" law. Objects are lazy, if an object is moving, it wants to keep moving. If at rest, it wants to stay at rest.
II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.
- - I call that one "speed". To create acceleration you have two options, either reduce mass or increase power (if not considering other external forces like friction)
III. For every action there is an equal and opposite reaction.
- - And finally, I call this one "Balance". There will always be an equal trade between forces

Forces

Gravity

Every object in the universe has a gravitational force. Earth's gravitational force is 9.8N/Kg. Newtons are a measurement of force and kilograms are a measurement of mass. The force of gravity can be calculated

Fg= (m)(g)

g= gravitational constant

m= mass

Thrust

Pressure

Particles pushing on the inside of the container, the more particles the higher the pressure.

Water is incompressible. Air is compressible.

Energy source is the compressed air

The Bottle rocket's source of energy is the compressed air inside the bottle. Air at pressures above atmospheric pressure (14.7 psi) store energy. As the compressed air pushes on the water, the water exits the bottle. The reaction force produced by this water, propels it forward.

Drag

Air resistance is friction which opposes the movement of your rocket. The straighter your rocket stays the less drag there will be.

A nose cone will significantly cut down drag. The cone will help cut through the air reducing the amount of air resistance. When travelling under the speed of sound (1234 km/h in air at sea level) a rounded nose cones is the best shape.

Fins

They act the same way as they do on a arrow or a dart or a weathervane. Wind pushes on the larger surface area, and creates a high pressure region, pointing the weathervane in the direction of the wind.

Knowing this, how do fins help your rocket?

Fins positioned at the back will keep the rocket upright. Fins will help the rocket keep stability. Fins at the back of the rocket with a large surface area will have the most benefit.

So......

1. an object at rest/in motion will stay at rest/in motion unless acted upon, your rocket will not move unless the normal force is greater than the force of gravity.

2. F=ma, the greater the thrust and lighter the rocket, the faster your rocket will accelerate

3. action / reaction, air pushes on water and water propels the rocket forward through the principle of conservation of momentum.

4. Fins keep the rocket stable by allowing air to push back onto the fins when/if rocket goes sideways (therefore finding its equilibrium (where forces are the same on all sides))

5. A Round nose cone is better than pointy for a rocket traveling less than the speed of sound (1234 km/h)

Bottle Rockets