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My Vehicle Design (ASEN 2004) lab group and I engineered a glider from requirements down.
My Vehicle Design (ASEN 2004) lab group and I engineered a glider from requirements down.
Drag modeling, wing shape scoring, flow simulation, and rapid prototyping were utilized to design the model shown.
Drag modeling, wing shape scoring, flow simulation, and rapid prototyping were utilized to design the model shown.
The glider was designed for a range of 125 [m] and an endurance of 15 [s] with a wingspan of 1 [m] and an aspect ratio of 5.
The glider was designed for a range of 125 [m] and an endurance of 15 [s] with a wingspan of 1 [m] and an aspect ratio of 5.
Design Process
Design Process
The design and modelling process was extensive, and began with finding an accurate way of calculating the aircraft's Oswald efficiency factor at low Reynold's numbers (Induced drag at low speeds). Next, an aspect ratio (of 5) was chosen to remain constant through the glider's design. This value was chosen based on evaluating different aspect ratios ceteris paribus. A wide range of wing shapes were then scored by using a weighted sum of their range, endurance, and weight, with the best scoring shape being chosen to move forward with.
Next, the design was made stable by finding the necessary tail beam length for stability at the given trim condition. This length could then be implemented in the Solidworks model. Using the evaluate toolbox in Solidworks, I could quickly return surface area values and mass (foam mass given as kg/m^2) to the aerodynamic and stability models thereby improving their accuracy. Those models then ran again with an updated mass, and the design was iterated.
Flight Testing
Flight Testing
The Solidworks assembly, my main contribution to the project, allowed the team to quickly iterate designs. While the aerodynamic and stability models worked to return updated values, I used my time to make the glider as easily manufacturable and survivable. This would ensure we could make a lot gliders, afford to lose a lot of gliders, and perfect The Toss.
Once it was constructed, the glider (Skylar) was thrown from the third floor of the CU aerospace building in order to evaluate it's real-world flight performance. This was done 5 days prior to flight day to ensure ample time to make necessary design changes or repairs. Skylar performed well but was ruined in the snow and another glider (Skylar 2) needed to be fabricated.
Two gliders were manufactured this time, one with the previous tail incident angle of 6 [degrees], another with a tail incident angle of 3 [degrees]. The most recent iteration of the stability model pointed towards a 3 degree incidence angle, but this was after changing the stability equations so we were unsure which to use.
After testing both the group reached a consensus the 6 degree glider performed better. This glider was then thrown on the first official flight day at the aerospace building.
Skylar 2 flew for a long duration, but not straight. A quarter was taped to one wing in order to balance the roll. Despite this, the glider was blown into light poles twice in a row and was no longer flyable. After examining the glider in detail, the reason for the crooked flights was determined to be the result of manufacturing errors and bad super-glue jobs.
A final, third glider was manufactured with attention to detail and precision being the focus this time. This glider, in the video to the right, provided the best flight yet.
On the second and final flight day, Skylar 3 flew a distance of 92.1 [m] and had an endurance of 13 [s]. Our group also won the engineering award for our full modeling, design, manufacturing, and testing process.
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