RE: FLT800 Conspiracy Theory

Billy Brown (
Tue, 16 Feb 1999 08:37:11 -0600

Ian, I must have missed something. What exactly is the government supposed to be covering up in this mess? Absent some motive, I'm more inclined to suspect them of incompetence than malice.

On the topic of moving objects falling through atmosphere, I see several issues that seem to be getting muddled. Let me throw out a few points:

  1. An unpowered object, starting from rest, can not fall through atmosphere faster than it would through a vacuum. It doesn't matter what shape the object is, because any acceleration it gains from aerodynamic effects will be smaller than the drag from having to pass through atmosphere.
  2. An aircraft that has significant horizontal motion, and then goes into a dive, can easily fall much faster than it would in a vacuum. There is a rather complex aerodynamic effect that allows it to trade horizontal for vertical motion. I haven't seen anything that shows FLT800 to have 0 forward momentum - in fact, such a claim seems highly unlikely. Moving up at a steep slope seems to fit the evidence better, but that would leave the aircraft with significant forward motion when it starts its descent.
  3. We don't know exactly when the engines went out. Obviously, if some of them were still running when the plane went into its descent this would produce a very fast powered dive. This sort of descent can easily approach the speed of sound, even for otherwise subsonic aircraft.
  4. Air/aviation gas explosions are not limited to some puny level of force. I don't know who this info originally came from, but they're wrong. Depending on the exact mixing conditions you can get anything from non-explosive combustion to very large explosions. Under worst-case conditions (small droplets dispersed through a large volume of air before being ignited) the effect can be equivalent to several times the same mass of TNT. The air force makes some impressive bombs that use this principle.
  5. Burning fuel tanks sometimes produce a significant propulsive force - the tank can act like an inefficient rocket engine. Combustion that takes place outside the aircraft can also produce significant effects, especially if it is uneven. In a spectacular case like FLT800, with multiple leaks and clouds of burning debris, this creates a significant amount of experimental noise. Figuring out the exact effects of all this activity would take a lot of supercomputer time.

When you add up all these factors, it becomes obvious that you really can't say anything definitive about the fall rate of a crippled aircraft without a lot of detailed information. Even then, getting anything better than a rough estimate of its behavior would require a supercomputer-based physics simulation.

Billy Brown, MCSE+I