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Basic Aerodynamics

Last updated over 3 years ago
8 questions
Note from the author:
part of Water Rocket Unit

Answer all questions in Full Complete Sentences


You cannot use the word "it" as the subject of your sentences


All the answers are here in this assignment

Part 1

Aerodynamics is defined as “the science of how an object reacts to its motion through air”. Since our rocket will be traveling through air and not in space (there is no air in space), we need to review a few basics of science.

Though the diagram is that of an airplane the same basic forces also act on a rocket. There are four basic aerodynamic forces: thrust, weight, drag and lift.

THRUST:
We have discussed thrust earlier and as you recall, thrust is the force that makes rockets move. The rocket gets its thrust from the rocket engine. In our case air pressure creates the thrust to make the rocket move.
WEIGHT:
Everything has weight therefore the weight of our rockets is a concern in design and performance. The force of the weight wants to pull the rocket back to earth. If we want to make a rocket climb into the air we need to supply more thrust than it weighs. The heavier the rocket, the more thrust is necessary to overcome the force of gravity. When designing your rocket you want to make it as light as possible so that it can climb the highest.
DRAG:
Any object, such as a rocket, that moves through air will be resisted or slowed down by the air it is traveling through. This resistance is called drag. You feel drag when you put your hand out of the window of a moving car and felt your hand pushed backwards. In designing a rocket we want to keep drag to a minimum. The nose cone, the body tube and the fins will create drag on your rocket. We can reduce drag by shaping these parts in various ways.
1

Define the term aerodynamics

1

What are the four forces that act on a rocket?

1

What is the relationship between weight and thrust of a rocket?

1

Explain drag

You cannot use the word "it" as the subject of your sentences

Part 2

NOSE CONE:
The efficiency of various nosecone designs has been tested in wind tunnels. Because our rocket travels at subsonic speeds (below the speed of sound) a sharp pointed nose cone is not the best design. A slightly rounded (parabolic) shaped nose cone actually has less drag.
ROCKET BODY:
The body of any rocket is usually cylindrical (round) in shape and cannot be changed much. The amount of drag created by the body of the rocket comes from three places:
1. The Cross-Sectional Area. The wider the body of the rocket the more drag will be created.
2. Base-shape. The shape of the base (bottom end) of the rocket can create drag by making a “suction area” behind the rocket that slows it down. Making the end tapered as shown below can reduce this.
3. Finish: Simply stated the smoother you make the outside of your rocket the less drag you will create.
1

Describe the shape of the best nose cone

1

List three ways we can reduce drag created by the body of the rocket

You cannot use the word "it" as the subject of your sentences
Part 3
FINS:
The fins and any other object attached to the rocket will create drag. Although fins create some drag they are needed in order to make the rocket fly straight and stable. Fins, like the nose cone should not have a sharp front edge. Fins work best at subsonic speeds if the nose is slightly rounded and the trailing back edge is sharp.
LIFT:
For an airplane, lift is the force that overcomes weight (gravity) and allows the airplane to fly. (Remember, for a rocket, thrust is used instead of lift to make the rocket go up). However, we need to study lift to see how the fins work in controlling the rockets flight path through the air.
The fins are like the wings on an airplane. The wing will create lift when the air is made to flow faster over one side of the wing than the other side of the wing.
Look at the diagram above. When the wing (fin) is angled as shown the air flows faster over the top of the wing. This creates lift and pushes the wing up
1

What is the best thinkness of a fin?

Required
1

Check each of your answers, did any of your sentences start with the word "it", if so please fix