Glider Design Challenge
Erin Mowbray 10/26/15 Aerospace Engineering
Glider Design:
Ryan and I entered certain variables into the AERY software based on the constraints given by our teacher, Ms.Harlan. Every other variable we entered was based on our personal preference and what would allow our glider to fly. For example, our teacher told us our fuselage couldn't be longer than 70 cm so Ryan and I decided to make it 65 cm. That way it wouldn't be too long and it would be easy to measure out and construct. We tried to make each measurement an exact whole number, that way it would be easy to measure and build, making the construction process as simple and efficient as possible, this is shown in detail on the 4th picture of the slideshow below.
Ryan and I entered certain variables into the AERY software based on the constraints given by our teacher, Ms.Harlan. Every other variable we entered was based on our personal preference and what would allow our glider to fly. For example, our teacher told us our fuselage couldn't be longer than 70 cm so Ryan and I decided to make it 65 cm. That way it wouldn't be too long and it would be easy to measure out and construct. We tried to make each measurement an exact whole number, that way it would be easy to measure and build, making the construction process as simple and efficient as possible, this is shown in detail on the 4th picture of the slideshow below.
Benefits of Computer-Based Models:
The AERY software provides you with all the calculations needed to be able to conclude whether a glider will be able to fly or not. It takes all the measurements you put into the program, then calculates all the statistics you would otherwise have to calculate by hand. Some of these stats include the location of the center of gravity, neutral point location, estimated mass, throwing velocity, flight angle of attack, estimated glide angle, estimated stall velocity and estimated stall angle. These stats could be calculated by hand, with the help of a calculator and formula sheet. For example, velocity could be calculated by multiplying speed x direction.
The AERY software provides you with all the calculations needed to be able to conclude whether a glider will be able to fly or not. It takes all the measurements you put into the program, then calculates all the statistics you would otherwise have to calculate by hand. Some of these stats include the location of the center of gravity, neutral point location, estimated mass, throwing velocity, flight angle of attack, estimated glide angle, estimated stall velocity and estimated stall angle. These stats could be calculated by hand, with the help of a calculator and formula sheet. For example, velocity could be calculated by multiplying speed x direction.
Glider Construction:
In order to properly construct a glider design into an actual model, one needs to have some prior knowledge with aircraft and construction. For example, one needs to know how to properly cut balsa wood, so that it leaves a smooth cut. Also, one needs to be able to read measuring tools correctly, like a ruler, to make sure each glider part is the exact size it needs to be. Lastly, one needs to be able to read the glider blueprint with dimensions, to properly measure each part as specified with the AERY software.
In order to properly construct a glider design into an actual model, one needs to have some prior knowledge with aircraft and construction. For example, one needs to know how to properly cut balsa wood, so that it leaves a smooth cut. Also, one needs to be able to read measuring tools correctly, like a ruler, to make sure each glider part is the exact size it needs to be. Lastly, one needs to be able to read the glider blueprint with dimensions, to properly measure each part as specified with the AERY software.
Conclusion Questions:
- Explain which glider or aircraft term were difficult to understand and the correct definition. Root chord~ part of airplane wing...side of a wing attached to fuselage Taper ratio~ used to approximate elliptical span wise load distribution
- Explain any challenges if someone else were to construct your design using the AERY print. If someone were to construct our design, they would have to be very precise/ use precise instruments to calculate/ measure angles and ratios.
- Explain any challenges faced using the AERY software and how you overcame those challenges. One of the major challenges with the software was that it took SUPER long for me to get the software up and running. Another problem was the instructions/info given about why the plane wouldn't fly was very vague, which meant I had to do a lot of guesswork until the plane could fly.
- Explain difficulties faced with this second design challenge compared with the first challenge. Because I had to refine the design for the second time. I had to be more precise. the first time, all I had to do was get the plane to fly, but the second challenge wanted me to refine and improve my original design. So I had to experimentally change parts (to improve efficiency) without changing the whole design concept.
- Explain how these constraints impacted your glider design compared to the first. The 2nd glider design was more efficient/effective. The plane flew better (more stable) the second time compared to the first. This means it had better pitch and directional stability.
- Funding for a new project is always limited in some way. How does the proposal process ensure that the idea being proposed will satisfy the project requirements? The proposal process allows someone to share their ideas and test if they would work, if not, they are allowed to fix it to the constraints given. Plus a project is more likely to be funded if it meets all project requirements. They are also more competitive, one would want their idea to be the best it can be so it has a better chance of being selected.
- Projects fail not due to a lack of solid designs but instead due to other issues. Describe these issues and explain how the proposal process ensures that the design with the highest likelihood of success can be selected. Some issues include lack of money, lack of planning, lack of resources etc. The proposal process creates competition and allows different designs to be compared, and the one with the least amount of issues wins/gets accepted.
- Describe the most persuasive elements of your proposal. The most persuasive elements of my proposal are the high evaluation number (140) that proves it will fly if constructed correctly, as well as the ease of construction.
- Explain why someone would have either a positive or negative impression after reading through your proposal for the first time. Someone would have a positive impression after reading through my proposal because they would see how easy it is to construct and that it will be able to fly when built properly.
- Was the glider as stable as you expected? Why or why not might this be so? Yes, the glider was just as stable as expected. I think this is because my partner and I built the glider to the exact constraints as shown using the AERY software. We built the glider to be balanced on all sides, and so it flew balanced.
- What techniques did you use to “trim” the glider for straight and gently descending flight? I used clay to act as an extra weight on whatever part of the glider needed to be balanced. For example, to make the glider gently descend, I had to add some clay to the nose of the glider to give it a little more weight, and to act as a buffer.
- How many test flights were required to get the glider trimmed for long distance, straight-line flight? Was this expected? Why or why not? About 12 test flights were required to get the glider trimmed. This was expected because we had to test it originally, and then test the glider after each alteration was made, to figure out if the change helped or harmed the flight of the glider.
- Explain the strengths and weaknesses of a competitive trial as a method to identify an optimal design. The strengths of a competitive trial include being able to see what design flies the best, is most durable etc. The weaknesses include not being able to conduct a fair competition, because of all the diversity in designs, as well as not being able to compare all the strengths and weaknesses of each design.
- Explain differences between your glider’s performance through flight-testing that was unexpected based on the AERY software predicted flight characteristic. My glider's performance during flight-testing was a lot better than what was predicted through AERY software. My glider flew a lot better than most other gliders from our class, despite the fact that my AERY evaluation number was a lot lower than the other gliders built. For example, the glider I designed had an evaluation number of 140 and flew 50 ft. Another glider had an evaluation number of 230 but only flew 38 ft.
- Based on the entire flight test data, from every group, explain conclusion that you can make about optimal glider designs for long distance flight. An optimal glider design, for long distance flight, needs to be balanced on all sides, with a lot of surface area exposed for the wings. The wings should be curved to be more aerodynamic and to decrease friction and drag. The glider itself should be larger in size, without weighing a lot. This ensures the glider will be stable enough during flight and also that it can withstand the forces of drag and weight to travel a long distance.
