Tuesday, February 01, 2011

The Physics of Top Gun -- Just Don't Borrow the Video

"You've lost that lovin' feelin'*, whoa that lovin' feelin'. You've lost that lovin' feelin', now it's gone, gone, gone, whoa..." Apparently China's state broadcaster, China Central Television (CCTV), lost that lovin' feeling last week when it allegedly lifted part of the 1986 movie "Top Gun" for a military promotional video that aired nation-wide in China.


Oops.

Thanks the wonders of the Internet, it wasn't long before someone noticed the similarities between the CCTV video and the 1980s flick. The Wall Street Journal (WSJ) put out the video above, comparing the original movie footage and the Chinese military training video. CCTV, according to the WSJ, hasn't yet made any comments about the coincidence.

But who can blame the Chinese? According to the Top Gun Wikipedia page, the number of men who joined the Navy with hopes of becoming Naval Aviators increased by 500 percent after the movie premiered.

I remember first watching Top Gun as a kid and being enthralled with the awesomeness of fancy flying. But I also had many questions about how lots of things in the movie worked. So, today, I thought I would answer some of those questions:

(FYI-The "Geek Out" info is when I totally geek out and over-answer something. If you're not feeling like plowing through an overdose of information, feel free to skip!)

Q. What is a "hard deck"?
Answer: Maverick got in trouble in one of his Top Gun training exercises for flying below the hard deck to take a shot at the enemy. What to me sounds like an ominous horizontal wall is actually just a term for the lowest altitude at which pilots agree to mock dogfight during flight training exercises. According to the website www.tailhook.org, the minimum altitude for Top Gun pilots in the early days was 10,000 ft. AGL.

Geek Out Info: You might ask, what is 10,000 ft. AGL? Altitudes are measured in a handful of ways. One measure of altitude is an airplane's height above ground level, or AGL. This differs from a plane's true altitude which is a measure of the plane's height above mean (average) sea level (MSL).

Airplanes altimeters (instruments that display height) measure their altitude based on air pressure. Since air pressure decreases uniformly with height, a known decrease in pressure is associated with a certain altitude. Since the air pressure at the ground is not always the same (it varies thanks to the weather), pilots always correct their altimeters for the current pressure at the airfield before taking off. If, after being corrected, the altimeter displays the known height above sea level for that airport (125 feet, for example, at the Los Angeles International Airport), the pilot knows that the altimeter is working properly.

Q. During one of his training dog fights at Top Gun, Maverick uses the brakes on his airplane to cause the plane chasing him to fly right by. How do brakes work on an airplane?
Airplanes have a variety of air brakes that increase drag and help them to slow down. Air brakes are easily seen on the tops of commercial aircraft wings during landing. They look a lot like flaps, except they are on top of the wings, "standing" nearly perpendicular to the wing. As you can imagine, having a sail-like object going against the wind on the top of a wing helps to slow an airplane as it rolls down the runway.

The rear spoiler on the Bugatti Veyron tilts to a 55 degree angle to help stop the car when its driver applies the brakes anytime the car is traveling faster than 200 mph.

Q. Why do the wings on an F-14 Tomcat move?
Technically, the wings on the F-14 are called "variable-sweep wings." When the fighter takes off, the wings are swept back only a little and the plane looks like most other aircraft. Having the wings at nearly a right angle to the aircraft helps it to get more lift -- something necessary during take-off and landing.

The F-14's wings are swept back when it travels supersonically. The delta-shaped wing configuration common to many supersonic aircraft reduces drag, helping the plane to travel at high speeds more efficiently. At fast speeds, thrust from the engine is more important that lift from the wings, so moving the wings back out of the way helps the plane move quickly. Though the F-14 is one genuinely cool plane, it no longer flies off and on aircraft carriers. The U.S. Navy replaced F-14s with the F/A-18 Superhornet in 2006.

Q. Why did Maverick and Goose have to eject from their airplane when it entered a spin? Can't airplanes get out of spins?
Yes, airplanes can get out of some spins, but not all. The type of spin Maverick's plane entered is called a "flat spin." During a flat spin, the airplane is directly parallel to the ground -- it's nose is pointed almost directly at the horizon. A plane can get into a flat spin if it's weight is not distributed properly, changing its center of gravity until it no longer flies correctly.

In a flat spin, air is not flowing over the airplane as it is expected. The airplane's controls no longer work effectively and cannot steer the airplane out of a spin. Because airplanes get "stuck" in flat spins, pilots often have little choice but to eject as Maverick and Goose did in the movie. If, however, a plane is in a spin while its nose is pointed up or down, a properly trained pilot should be able to recover from the spin.

Geek Out Info: In most spin situations in small aircraft, the pilot usually follows the 'PARE' method of escaping a spin. First, he or she brings the 'P'ower to idle, moves the 'A'ilerons (the flap-like things at the ends of the wings that make a plane roll) to neutral to stop the plane from rolling wing over wing, applies the opposite 'R'udder to the direction of the spin (if the plane is spinning left, the pilot steps on the right rudder) and moves the 'E'levator (which controls pitch up and down) to neutral. This technique stabilizes the airplane so that the pilot can regain control.

Doesn't all this airplane talk just make you want to watch Top Gun again? Just don't borrow any of the movie for your military training video...

*"You've Lost that Lovin' Feelin'" by The Righteous Brothers

3 comments:

  1. Advanced Geek Out Info: Swept wings make air think it's traveling subsonically over a wing that is accelerating airflow (remember that air flows faster over a wing than under). Only the component of the airflow perpendicular to the wing edge is applied to making shockwaves. This is why airliners (which fly at the low end of transonic speed, fast enough to generate sonic shocks over straight wings) have swept wings. Swept wings, though, have awful low speed lift characteristics, so most swept-wing airliners have flaps that extend out as well as down as well as leading edge extensions and slots, that make the wing look a lot "straighter" on take off... the airliner (easier to engineer) version of variable geometry wings!

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  2. Top Gun at CCTV

    Oh, come on. There are fans of Top Gun at CCTV. A maverick employee was overcome by "that loving feeling."

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  3. Anonymous #1: Thanks for the advanced geek out info. Very cool insight to the really complex design of airliner wings. Love it!

    Anonymous #2: How can I argue with that?

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