SJSUSPARTAN
Active Member
Physics are for the Birds
If anyone hangs around me long enough, they will know that I can be a bit of a "prop head". The term means that I'm an aircraft enthusiast, but my interest focuses primarily on military aircraft. As a child I fell in love with airplanes, mainly because my dad had an interest in them and my family has a history of serving in the United States Air Force. Anything having to do with flight captured my interest. Some of my favorite movies I still look back on fondly, remembering how I would watch them and dream of soaring amongst the clouds. Of course, the more we learn about something that interests us, we can learn to see inconsistencies when seeing what hollywood has to show, versus what real life has to say. Can moves like this even be possible? What if I tried it? How would it work? Three of my favorite movies, The Rocketeer, Top Gun, and Red Tails, have moments with some amazing flight aerobatics. However, these are also embellished for the sake of entertainment.
In kindergarden, my absolute favorite movie to watch was Disney's The Rocketeer. It had airplanes, action and a superhero flying around with a jetpack, so what five-year old wouldn't be interested in it? In the movie, Cliff Secord, the character who later becomes the Rocketeer, finds an experimental rocket and straps it to his back in order to fly. At first the rocket is very unstable, but after Cliff's friend Peevy makes a helmet with a single rudder blade on it, flying with the rocket is much easier. I did not pay this much attention as a kid, but today I see where "just" adding a rudder would not significantly aid in flying with a rocket attached to one's back.
Strapping a rocket to yourself could allow you to fly. However, it would be wise to cool one's jets and address several critical factors before hitting the On switch. The first issue to address lies in the name "Rocketeer". A rocket is basically a jet engine, but does not require airflow to help produce the thrust it needs to gain momentum. Instead, rockets work through fuel reactions in a combustion chamber, through which the exhaust creates thrust. Of course this heated gas is very intense, and, I would imagine, would burn right through Cliff's chaps before he even left the ground. But if fire-retardant clothing was available and Cliff's backside was safe from third-degree burns, the next question he would face would be how to get off the ground. When dealing with jet engines for flight, the thrust to weight ratio has to also be considered. The backpack-sized rocket compared to Cliff's own body mass makes for great fantasy, but realistically would not work. The rocket would need to have a properly sized combustion chamber that would produce enough thrust to lift Cliff off the ground and continue to propel him at a constant rate once he hit his terminal velocity. As a general rule, he would want his thrust to weight ratio to be 1:1, with thrust being more desirable.
When Cliff finally gets his thrust to weight issue worked out, he has to address his maneuverability issue. The human body is not made to fly, and in general is not very aerodynamic. So Cliff would have to construct a flying wing surface in order to control his flight. The addition of a rudder to the helmet could help in theory, but would only serve as a vertical stabilizer when in the air. For Cliff to maneuver, his wing surfaces would have to be shaped in such a way that will catch the wind under them, producing lift, while at the same time allowing the air to flow over them without too much drag which would destabilize his flying. This wing would solve the issue of getting lift while in the air, but what about controlling vertical pitch and Cliff's ability to roll himself in any direction? If we go back in time to World War II, the german luftwaffe had a rocket powered intercepter aircraft which solved this issue; the ME-163 Komet. The ME-163 had a vertical stabilizer much like what Cliff has on his helmet, but also employs a "delta wing mix" for its maneuverability. This means that the wing's ailerons, which allow it to roll left or right, also serve as elevators, allowing it to go up and down. If Cliff were able to have a wing like the ME-163 that did not hinder his thrust to weight ratio he would most certainly have a much easier time flying around and saving the day.
The second movie where flight dynamics are exaggerated is Top Gun. The movie has some very entertaining dogfights between the pilots, but when observed closer, many characteristics of the aircraft defy physics. However, to understand some of what is going on in the movie, I think it would be helpful to understand jets and their history. The first operational jet fighter, the german ME-262, emerged during World War II. It was equipped with two jet engines making it over one-hundred miles per hour faster than any other fighter aircraft. After the war, this jet propulsion technology was studied and adopted for the next generation of military aircraft were turbine powered, swept-wing fighters reaching speeds capable of breaking the sound barrier for the first time ever.
In Top Gun, Tom Cruise pilots the F-14 Tomcat. The F-14 is an interceptor jet, meaning it's built for speed above all else. The F-14 uses a swept wing design to achieve it's incredible speed, but when it's wings are folded, maneuverability is very limited. Like most modern jets, the wings have flaps to allow the jet to slow down, while still giving it enough lift to stay airborne. However, when Cruise "slams on the brakes", the nose of his jet pitches upward at a high angle. In a more realistic situation, his jet would not have nosed up so much, nor kept up the speed he seemed to maintain. The speeds he was flying at would have most likely torn his "brakes" from his wings, or have his wings ripped off completely. What we see is Cruise's F-14 pulling upward, or attempting a "cobra" maneuver. The cobra maneuver forces the jet's engines down and the nose up, before pointing back to a level position. There is a moment we where we see what Cruise is doing inside the cockpit, before we see the jet's reaction, which is exactly what a pilot would do in order to perform this move. In the F-14, the jet would be pitch at a ninety-degree angle, bleeding off a lot of airspeed, before nosing forward for Cruise to get a targeting angle on his enemy.
To many who don't understand flying, they may not see a difference between flying jets and flying propeller-driven planes. The main difference, other than speed, is airflow. Jets, due to their turbines behind housed inside their engines, need to be moving fast enough in the air and on take-off to get enough airflow passing over the control surfaces in order to move the plane. With propeller planes, the spinning of the prop gives additional airflow over the surface of the wings, rudder and elevator, giving it a shorter take off, and tighter handling. In the movie Red Tails there are a couple moments where the pilots pull amazing aerobatic maneuvers that don't seem physically possible.
In the movie Red Tails, both "Pretty Boy" and "Lightning" are the hot shot pilots of their squadrons. During some dogfights, both pilots use what we call a "snap roll" to skid their planes in mid air, allowing them to get onto their opponent's tail. The snap roll requires the pilot to chop their power while hitting hard on their rudder control. This drops the plane's airspeed, but only for a little while, since the prop wash creates the airflow for the plane, allowing it to stabilize much faster than a jet. However, despite this maneuver being nearly flawlessly displayed, the rapid loss of airspeed would cause the Pretty Boy's ME-109 or Lightning's P-51 to drop their altitude. Lightning's P-51, being at high altitude had little to worry about, due to being high enough that he would not have to worry about dropping altitude too much. In addition to his altitude, Lightning had also deployed his plane's flaps in order to keep up the amount of lift needed to maintain a more level flight coming out of his maneuver. Pretty Boy, on the other hand, showed no sign of using his ME-109's flaps, assuming that his plane had any. The ME-109 is a lighter plane when compared to Lightning's, which may have aided it in not dropping altitude too drastically, before regaining control.
As I said before, I am very much an aircraft enthusiast. But why do I bother telling you this when there's a very good chance you aren't into planes as much as I am? The answer: what if. What if you, the reader have a secret passion for aircraft, and now you know a little more about them. What if you're one of those people who sit at the international airport, just watching the jets take of and land, and now you have a little more info about why the runways are so long. What if you dream of becoming a pilot? Now you have some information about how flight really works. What if you, at one point, wanted to join the Blue Angels aerobatics team? Or what if you're like me who loves to fly scale, R/C versions of your favorite aircraft. What if you're like me and want to try your hand at performing these maneuvers, just to see them up close? I can tell you first hand, the first time you see it first hand, and you're the one making it happen, it will bring the biggest smile of excitement to your face. Even if you're not into it right now, I encourage you to give it a shot, either in real life, or in a simulator. So fly on.
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