Originally Posted by cyrus15
Let’s get back to basics:
Good idea. Let's call it "Science 101".
1. How can a CWT explode in mid air only in that particular aircraft during normal flight, though B747 been in service since 1973. (Supposedly no act of sabotage involved in here).
Probably because great care is taken to keep ignition sources away from fuel tanks. So only very rarely there will be one. The mode of ignition in this accident has never been identified definitively.
2. At 13000 feet, air (oxygen) can’t enter the fuel tank due to low ambient pressure and even in empty or half / quarter tank full; the pressure is equalized as the altitude changes. So the possibility of air getting in is not there not to mention the existence of fuel vapor pressure that occupy the empty space seeking lower pressure area to escape well prevent any air to get in (this is during flight).
Now let's see.
Tanks have vents.
Fluids (i. e. gases and liquids) stream from regions of higher pressure towards regions of lower pressure. What is the pressure inside and outside the tank?
If we go along with your premise that no air was in the tank to begin with (more on that later), the only thing inside the tank to create pressure is the fuel vapor pressure. The only value I have found is for JP-8 at 38 degrees Celsius: it is about 200Pa. Another document about Jet-A1 mentions "less than 10hPa", so, let's be generous and assume 1000Pa.
Ambient air pressure at 13,000ft is around 50,000Pa, i. e. 50 times the inside pressure.
To figure out which fluid will stream into which direction is left as an exercise to the reader.
3. If the electrical devices in the fuel tank are electrically shorted or overheated (incase of running dry) what’s the possibility during flight to have fire or explosion in this condition? Where the needed oxygen should come from?
Well, from the air, I guess. See above. The correct solution to the exercise above is: it will stream from the outside into the tank, because the pressure outside the tank is higher than inside. One of the characteristics of jet fuel is its very low vapor pressure.
An additional thought: Why do you think many modern jet airliners have tank interting systems, which feed nitrogen-enriched air into the tanks, to reduce the amount of oxygen, to reduce the chances of creating a flammable fuel/air mixture.
I also recommend actually reading the TWA800 accident report. The investigators did actually test fuel/air mixture ratios in actual fuel tanks in flight and found them to be in the flammable range. See section 1.16.5.1.1.1 of the report.
4. How fire extinguisher works?
Many different ways. Some (the most efficient, like Halon) are chemical inhibitors that bind free radicals, thus breaking the reaction chain. Others replace the air (oxygen) around the fuel to stop the reaction. Water (water vapor) and foam are common.
5. The theory of fuel tank explosion in mid air has been talked about and discussed in a span of couple of days after the accident and before even the wreckage recovery started. Four years later in a televised conference, all agencies (NTSB, FBI, FAA etc.) Conclusion was “fuel tank explosion”.
Interesting. A theory that is discussed early on can never be true?
6. Commercial jet engines operation principal are not the same as rockets or space shuttle engines so do the fuel used in both engines are not the same (no oxidizers in jet fuel and no after burner engine used).
True. Same for military jet aircraft. Btw. liquid rocket fuels do not contain oxidisers, either, those are separate. As a side note, the most powerful rocket to date (Saturn V) used kerosene as its primary-stage fuel.
8. Most fuel injected cars (gasoline) has pump in the fuel tank, it is DC powered type of pump, that didn’t cause any concerns of the DOT, NTSB and other regulatory agencies knowing that gasoline is more volatile than kerosene based jet fuel and still the same principal fuel tank designed used. Road Accidents are more likely to cause automobiles fire but not the fuel tank will be on fire by design flaw.
The fuel pump as such was not found to be the ignition souce. Secondly, car fuel pumps are usually not submerged in the tank, but somewhere down the line, which their electrical parts away from the fuel line.
magnesium fire is a problem because it can produce oxygen when it burn.
No. Magnesium fire does not create oxygen (where from?)
Magnesium fire is a problem because it continues burning under water, because, very simply put, oxygen binds stronger to magnesium than to hydrogen (in the water), so magnesium "uses" the oxygen in the water molecules to burn, thereby freeing hydrogen.
Divers use magnesium torches.
· Four years later and millions of dollars spent to tell the same wrong conclusion that started in a matter of days after the accident?
What's wrong with a few smart people having the right hunch from the beginning? Or with an extensive investigation to find out the real cause.
I think so.
Bernd