We Finally Have the Answer, Does Superman's Cape Slow Him Down?
A new study has been conducted that will put an end to playground debates and heated comic book store arguments worldwide. It answers the question, does Superman's cape slow him down?
The study, posted on Reddit, was carried out as a student's final project in a low-speed aerodynamics class.
An Iron Man — not Superman — figurine was placed inside the university's low-speed wind tunnel to take the readings.
One of the greatest Mythbusts
Redditor Th3Fa113nCru5ad3r (who we'll now refer to as OP — original poster — or the student for obvious reasons), outlined the findings of the study 9 September in a post titled: "One of my greatest Mythbusts (If you flew like Superman, does the cape actually slow you down in flight?)"
The OP described how all of their colleagues "decided to do studies on F-117s, F-16s, and other aircraft to replicate previous studies performed."
OP, meanwhile, decided to study the aerodynamics of a much more powerful entity, Superman.
The student said the inspiration came from the scene in the Pixar film The Incredibles where the character Edna Mode says "no capes!"
The study was based on the fact "that society is pretty convinced that capes offer no advantages in flight, but no data was present."
How was the study carried out?
For the experiment the student wanted to measure the forces acting upon a "Superman" traveling at flight speeds of Mach 0.2 - 0.7, using Reynolds numbers — a value that can be "used to scale models to their full-scale counterparts in flight." OP said its similar to that of a jet fighter.
The student reasoned that this would be close to the speed Superman would fly, assuming he is not breaking the sound barrier.
The Iron Man figurine, OP said, is also streamlined enough to be used in place of a Superman figurine.
A strain gauge was attached to a piece of PVC pipe and the pipe epoxied to Iron Man's groin. This way, the OP says, they could place Iron Man in a flying pose, ready to be tested in the wind tunnel with and without a cape.
"Engineering mathematical magic"
After running the experiment, the OP described how the drag forces caused by the airflow sweeping across the figurine would deflect the PVC pipe, causing the gauge to be "strained."
"Using some engineering mathematical magic," the student was able to translate the voltage reading from the strain gauge to total drag force experienced.
The student's experiment used Newton's 2nd law of motion as a reference: F=ma (F=d/dt(mv)). This law states that the sum of the forces exerted on an object is equal to the object's mass times acceleration.
This law can be used to measure the relation between drag force (from a cape) and flight velocity of an object (Superman).
The control for the experiment saw OP test the figurine without a cape.
The variables were scaled capes of different materials and sizes.
The student used muslin fabric, a lightweight material that is typically used to test patterns for clothing and nylon fabric, which is a heavier material used in costume designs for capes and superhero suits.
Each of the material was tested in three different sizes; short, medium, and long (the last being roughly 14" inches in length).
After a day of testing in the wind tunnel, the student came up with the following results.
The OP described the results in the following words:
"At first, I thought something was wrong with my test setup, however, after conferring with my professor and other university faculty, to my own amazement, the heavy and bigger the cape is, the less drag force is experienced. Basically, you fly faster with capes!"
One caveat was that "the larger and heavier the cape, the more it's gonna flap around, creating instability." However, "the average of those fluctuations still deems lower drag forces than without a cape."
The OP concluded that "the cape acts like a streamlined surface that helps to delay the separation of the airflow to further downstream of the figurine, resulting in a smaller separation area and therefore a lower profile drag. The longer the cape, the further downstream the separation."
Much more detail can be found on the different drag forces in action during the experiment — skin friction drag and profile drag — in the original Reddit post.
The student said the final project was a winner. Next up, having the research published.
Answering a commenter's question on Reddit, the OP said:
"My group has a research paper written, and I’m currently in the works of getting it submitted to an academic journal. Once that happens the paper will be released!"
Is it a bird? Is it a plane? Redditor Th3Fa113nCru5ad3r has successfully answered the most burning question anyone has ever had about Superman.
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