Here is the main gist of the experiment that I am going to carry out:
Topic of Investigation: Speed- how length of each
blade affects the speed of the ‘submarine'
Aim: To find out if the length of the blade of the propeller affects the speed of the model submarine
Independent Variable: Length of the blade of the propeller
Dependent Variable: Speed of the submarine
Hypothesis Statement: The longer the length of each blade
(15 cm being the longest), the greater the speed of the ‘submarine’.
Research Question:
- Will the length of each blade on the propellor affect the speed of the submarine?
- What are the factors that contribute to the difference in speed of the ‘submarine’ when different lengths are used?
Here is a short summary on research done on the area of investigation:
A submarine is a craft
designed to float on the surface, and navigate the depths of the oceans. The
most basic things that will determine the effectiveness of a submarine are:
propeller and buoyancy. However, unlike a ship, the submarine is able to
control the buoyancy- whether it wants to float, or sink. On the other hand,
the propeller on a submarine works to convert the rotational energy of a shaft
into propulsion. The propeller has blades attached to a heavy central hub. The
blades are inclined to the place of rotation. Besides the angle, the diameter
of the propeller is a variable that affects the speed and distance at which the
submarine moves. The diameter is simply the distance across a circle swept by
the extreme tips of the propeller. The theoretical distance travelled for one
revolution of the propeller is called ‘pitch’. The pitch will differ according
to the diameter of the propeller. Submarines are designed based on several
factors: blade angle of the propeller blades, diameter of the propeller disk,
curvature of the blade airfoil and the number of blades. However, these are
often adversely affected due to the blade angle, blade length and revolutions
per minute. In this experiment, the main area of study is the length of blades
of the propeller, in other words, the total diameter of the propeller.
Acknowledgements:
- Propeller Basics, http://www.propellerworld.co.uk/Prop_Basics,_how_propellers_wor.html, accessed on 14 April
- How Stuff Works- Submarine http://science.howstuffworks.com/transport/engines-equipment/submarine1.htm accessed on 14 April
- Number of Aircraft Propeller Blades http://www.aerospaceweb.org/question/propulsion/q0039.shtml accessed on 14 April
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