Introduction: (Initial Observation)
The airplane was invented in 1903 by Orville & Wilbur Wright. Before the Wright brothers, many others made varieties of wings and kites as an instrument of flight. Of course not all designs were successful. For many years fabric and wood have been the main material used in the construction of kites and airplanes. Regardless of the materials used in construction of an airplane, certain designs have had more success than others. Such successes and failures became the foundation for developing a new branch of physical science called aerodynamics. Model airplanes made from paper or balsa wood follow the same aerodynamic rules as larger airplanes. The purpose of this project is discovering some of the aerodynamic concepts and experimenting some possible airplane designs.
Please read different questions and different experiments suggested in this project guide and choose one of them as your science project.
Information Gathering:
There are many books and publications about the history of the airplane and different models of airplanes exist. However for this research we rely on internet sources such as two of the following links. More information can be found if you search for phrases such as history of airplanes or airplane design. Following are two links that I recommend.
Four Forces on an Airplane
A force may be thought of as a push or pull in a specific direction. This slide shows the forces that act on an airplane in flight.
Weight
Weight is a force that is always directed toward the center of the earth. The magnitude of the force depends on the mass of all the airplane parts, plus the amount of fuel, plus any payload on board (people, baggage, freight, etc.). The weight is distributed throughout the airplane. But we can often think of it as collected and acting through a single point called the center of gravity. In flight, the airplane rotates about the center of gravity, and the direction of the weight force always remains toward the center of the earth. During a flight, the airplane’s weight constantly changes as the aircraft consumes fuel. The distribution of the weight and the center of gravity can also change, so the pilot must constantly adjust the controls to keep the airplane balanced.
Lift
To make an airplane fly, we must generate a force to overcome the weight. This force is called the lift and is generated by the motion of the airplane through the air. Lift is an aerodynamic force (“aero” stands for the air, and “dynamic” denotes motion). Lift is directed perpendicular (at right angle) to the flight direction. As with weight, each part of the aircraft contributes to a single aircraft lift force. But most aircraft lift is generated by the wings. Aircraft lift acts through a single point called the center of pressure. The center of pressure is defined just like the center of gravity, but using the pressure distribution around the body instead of the weight distribution.
Drag
As the airplane moves through the air, there is another aerodynamic force present. The air resists the motion of the aircraft; this resistance force is called the drag of the airplane. Like lift, there are many factors that affect the magnitude of the drag force including:
- the shape of the airplane
- the “stickiness” of the air
- the speed.
And like lift, we often collect all of the individual components’ drags and combine them into a single aircraft drag magnitude. The direction of the drag force is always opposed to the flight direction, and drag acts through the center of pressure.
Thrust
To overcome drag, most airplanes have some kind of propulsion system to generate a force called thrust. The magnitude of the thrust depends on many factors associated with the propulsion system:
- type of engine
- number of engines
- throttle setting
- speed.
The direction of the force depends on how the engines are attached to the aircraft. In the figure shown above, two jet engines are located under the wings, parallel to the body, with thrust acting along the body centerline. On some aircraft (such as the Harrier), the thrust direction can be varied to help the airplane take off in a very short distance. For jet engines, it is often confusing to remember that aircraft thrust is a reaction to the hot gas rushing out of the nozzle. The hot gas goes out the back, but the thrust pushes towards the front. Action <–> reaction is explained by Newton’s Third Law of Motion.
A glider is a special kind of aircraft that has no engine. Some external source of power has to be applied to initiate the motion. During flight, the weight is opposed by both lift and drag, as shown on Vector Balance of Forces for a Glider. Paper airplanes are the most obvious example, but there are many kinds of gliders. Some gliders are piloted and are towed aloft by a powered aircraft, then cut free to glide for long distances before landing. During reentry and landing, the Space Shuttle is a glider; the rocket engines are used only to loft the Shuttle into space.
The motion of the airplane through the air depends on the relative strength and direction of the forces shown above. If the forces are balanced, the aircraft cruises at constant velocity. If the forces are unbalanced, the aircraft accelerates in the direction of the largest force.
Following are some additional links:
http://www.ctie.monash.edu.au/hargrave/wings_home.html
http://www.sciencemuseum.org.uk/on%2Dline/exhibitions.asp#
How to build the best paper airplane in the world
Airplane Design Program (advanced)
If you need more information on the above two factors, click on help above to contact your project advisor.
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
Which home made airplane designs fly best?
There are many design factors that can be studied for their effects on flight. Following are some specific questions who focus on some specific design elements.
- How does the wing span affect the distance an airplane can glide?
- How does the weight of an airplane affect the distance it can glide?
- How does the wing area affect the distance an airplane can glide?
- How does the weight distribution in an airplane affect the distance an airplane can glide?
Any of the above three questions can be the subject of an experimental science project.
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
You must define variables based on the question you choose.
This is how you may define variables for question number 1.
- Independent variable (also known as manipulated variable) is the wing span.
- Dependent variable (also known as responding variable) is the distance a model airplane can glide.
- Constants are the initial speed, height and other airplane design factors.
This is how you may define variables for question number 2.
- Independent variable (also known as manipulated variable) is the weight of the airplane.
- Dependent variable (also known as responding variable) is the distance a model airplane can glide.
- Constants are the initial speed, height and other airplane design factors.
This is how you may define variables for question number 3.
- Independent variable (also known as manipulated variable) is the wing area.
- Dependent variable (also known as responding variable) is the distance a model airplane can glide.
- Constants are the initial speed, height and other airplane design factors.
This is how you may define variables for question number 4.
- Independent variable also known as the manipulated variable is the center of gravity.
- Dependent variable also known as the responding variable is the distance a model airplane can glide.
- Constants are:
- The center of air pressure: This is directly related to shape and design and is affected by surface area of the wings and body.
- The initial ejection speed and height
- Other airplane design factors.
Hypothesis:
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
This is a sample hypothesis for the question number 1
As wing span increases, the airplane will be able to glide a longer distance.
This is a sample hypothesis for question number 4
I think if the center of gravity be aligned to the center of air pressure, air plane will have the best balance and will fly the best. (In more technical term, lift must balance weight)
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1:
How does the wing span affect the distance an airplane can glide?
Introduction: In this project you will perform experiments to determine how the wing span affects the distance an airplane can glide.
Procedure:
For this experiment use a simple balsa wood airplane with no propellers. You may purchase a simple balsa wood airplane model or use balsa wood or cardboard to make your own model.Click Here to see the samples of balsa wood airplanes.
When your model is ready test it a few times to make sure that it can fly. Make necessary adjustments as needed.
Most balsa airplanes that you may buy in stores are already tested and work fine.
In order to test and compare the flight range of different designs, you need to make sure that all designs are ejected (thrown) with the same force and the same angle. To do that you must make a catapult shooter duck.
Get a piece of wood about 1 x 3 x 24 to be the base for the shooter duck. Get two pieces of balsa wood or moldings about 12″ long each and glue them to the shooter duck as shown in the picture. The distance between these two must be slightly wider than the body or fuselage of your airplane model. Insert one nail in each side to hold a rubber band. Secure the rubber band to the nails. The shooter must be ready now.
Test the shooter to shoot a wood dowel or any other wooden stick.
Make some markings on the shooter so you know how far you are pulling the rubber band each time.
This shooter is for testing balsa wood airplanes; however, you may also be able to use it with paper airplanes if you glue a piece of cardboard to the bottom rare of paper airplanes.
Use your shooting duck to eject your airplane 3 times. Each time measure and record the distance your airplane can fly (glide) and record it in your data table.
Carefully Cut 1 cm from each end of the wings. This will reduce your wingspan by 2 centimeters. Repeat the flight test 3 times with the new wingspan and each time record your observations (flight distance) in your data table.
Continue to shorten the wings and repeat your tests until the wings are about 1/2 of their original size.
Your results table may look like this:
| Wingspan | Flight distance 1 | Flight distance 2 | Flight distance 3 | Flight distance average |
Use your results table to draw a graph.
Related experiments: You may also modify the shape of wings, the location of wings, the number of wings and the size of wings and test the airplanes that you make.
Experiment 2: Design paper airplanes or balsa wood airplanes and compare their ability to fly.
We make a simple paper airplane using a letter size or A4 size sheet of paper. This design has been around at least thirty years. In my opinion it’s still the best paper airplane there is … no hassles like paper clips, scissors, or tape. Plus, you can throw it indoors or outdoors.
1. Start with a 8.5″ x 11″ sheet of photocopy paper.
2. Fold the usual triangles.
3. Fold over to the right (just follow the picture)
4. Flip over, fold the triangles again, and flip back.
5. Fold over to the right (again, follow the picture)
6. Flip over.
7. OK, this part is a bit tricky. Think of the three circles as the vertices of a triangle. Rotate this triangle counterclockwise with the blue circle as the pivot point. Make it symmetric.
8. This is the top view.
9. Fold along the black & white lines to get the final result. If you do it correctly, you won’t need to bother with ailerons, flaps, etc. To make it turn, just lean the body one way or the other. Enjoy!
Your final airplane may look like this.
Test it a few times and then start your experiments to see how changes in design will affect the flight.
You may then modify the design in many different ways and test to see how your new design airplane fly.
Paper airplanes are very fragile and cannot resist the pressure of the rubber band. A piece of cardboard or balsa wood glued to the back of a paper airplane will provide additional strength to the paper; so it does not fold and deform by rubber band. Please note that this will make the back of the airplane heavier and you may have to add a similar weight to the front to give it a balance.
Also visit the following links for more ideas.
Materials and Equipment:
List of materials can be extracted from the experiment section. Prepare this list at the end, when you exactly know what material and tools you have used.
If you want to make your own balsawood airplane, you will need about 2 pieces of 4″ x 24″ balsa wood with thickness of 1/16″.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Calculations:
You need to calculate the average flight distance of multiple test runs of each design.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Conclusion:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
