As countless Birdman rallies have shown, building a powerless flying contraption, even for a single person, is not an easy engineering task. Not that it's ever been a concern for fictional superhero Bruce Wayne / Batman, who glides from tall buildings using nothing but his cape. But could he... really? A group from the Physics and Astronomy department at the University of Leicester in the UK decided to do the maths, using Batman Begins as a guide.
The results can be found in this paper, published in December last year and entitled "Trajectory of a falling Batman".
It should be stated the four researchers involved made a few assumptions, which the paper is happy to point out. For one, the feasibility of Batman's cape and the materials used in its construction are not considered, simply that it's good enough to provide "the shape of a rigid aerofoil".
Secondly, it's entirely possible for a wannabe Batman to alter his trajectory in an attempt to provide more favourable angles. The paper however uses numbers extrapolated from Batman Begins, including the dimensions of the hero's cape when fully extended.
I'm not exactly a maths whiz, so my brain went into hibernation after seeing the first theta, but thankfully for the trig-impaired, the paper presents its conclusions in plain English. For the Dark Knight, there is some good news:
Batman's descent is rapid, even for this high estimate for the lift coefficient. Looking at the case for gliding from a fairly tall building of height 150m, Batman can glide to a distance of about 350m, which is reasonable.
So far, so good, right? Not so much. As they say, it's all about the landing:
The problem with the glide lies in his velocity as he reaches ground level. The velocity rises rapidly to a maximum of a little over 110km/h before steadying to a constant speed of around 80km/h. At these high speeds any impact would likely be fatal if not severely damaging (consider impact with a car travelling at these speeds).
As cool as gliding with nothing but a cape might be, in reality, the end result would be a nice, Bat-pancake for Alfred to scrap off of Gotham's streets. The researchers say as much in the paper's parting words:
Clearly gliding using a batcape is not a safe way to travel, unless a method to rapidly slow down is used such as a parachute.
I think the bad guys would probably notice a parachute. It's also a tricky thing to fit into Gotham's tiny and dangerous alleys.
Images: Warner Bros. Pictures / University of Leicester