Drop tanks

[Gundamhead]

It doesn't, believe me, I've run about 20 of them in different sizes. model size diesel engines are compression ignition, no glow plug or anything, just an adjustable contra-piston which adjusts the compression ratio at TDC which is then sufficient to ignite the fuel/air mixture

Yes, but you do know, the compression of the air/fuel is the heat source, and the 'spark/ignition' in those engines. You still need an ignition source, air, and fuel for there to be fire or explosion. In your case the heat of compression is the ignition source. If your engine can't compress it enough it won't generate the heat from compression and it won't create the ignition, and it won't run because it's lacking one of the 3 from the ignition/fuel/air trinity.

Now to bring it all back on topic, a drop tank lacks the ignition. You'd have to add ignition for it to explode. A incendiary bullet, a grenade, a heat source, a faulty wire, static charge, whatever. Just dropping a drop tank to earth will not cause it to explode without the ignition. Think of automobiles gas tanks sloshing around and the car crashing. They don't go boom until there's an leak of fuel in the air to an ignition source like a hot exhaust, spark, or flame.

[Wayne S]

You, on the other hand, took 5 posts, 28 posts later, before you can even explain the nature of your initial objection, which you should have attempted to explain in the first place to avoid any misunderstandings.

I said it in the next post I made. Maybe now since you understand hopefully on the same pager, you will/would notice?

Jeff, looking at it just from the vapor stand point in the air, burning; The vapor is burning since the mixture and temperature has changed.

And that even leaves out the fact you confused burning with evaporation.

I did not confuse evaporation with burning. It was actually a play on words. Meaning that the petrol "Gas used for our cars" is starting to burning off. It does not have a gaseous state, It is the name of a liquid only. I could have said it starts to disappear.

At the time of writing it, the sun burning off haze came to my mind, so I wrote it the way I did. I was listening to the weather report at the time ;)

[jbrundt]

In order for there to be any fire/combustion/flame you need these ingredients:

1. Fuel

2. oxidizer

3. heat

Pretty basic.

For any liquid fuel to burn it needs to be a vapor. Why? It has to do with the ratio of surface area to volume. The more surface area present the better or more likely the fuel is to burn. Ignoring the normal evaporative process a bucket of Jet A has a very low surface area to volume ratio. Now, take this same Jet A and turn it into billions of tiny, tiny, tiny droplets and you have greatly (greatly) increased its surface are to volume ratio.

Note: this same surface area to volume ratio explains why grain elevators explode or that flour can burn

Now you have to add some form of oxygen. Obviously pure oxygen is the best but we have to make do with what's naturally in the air. It's more than enough at sea level for our purposes. The more oxygen you have the more intense the fire/reaction because there are more oxygen atoms to react with whatever fuel atoms available. Oxygen itself isn't flammable. It only promotes flame/combustion/fire. No oxygen, no flame. However, adding oxygen in sufficient concentration, will allow almost anything to burn. That's why you don't have any fire around oxygen.

Lastly you need some form of heat. Any form of heat will do. heat from a match, heat from a glow plug, heat from compression, heat from friction, heat from a spark. It doesn't matter what makes the heat, just as long as it is hot enough to start the chemical process of fire.

Once these three ingredients are present then you have fire. This is basic chemistry, something we all should have had in high school.

Now, explosions are a completely different animal. An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive". Subsonic shock waves are created by low explosives through the slower burning process known as deflagration.

When you add pressure to the mix (confining the burning process) then you have an explosion. The air/fuel mixture in an internal combustion engine is confined and under pressure so it produces more energy. Take away that compression and you still have the burning but not at as high an energy level. In a jet engine you reduce the compression level of the air going into the combustion chamber then the jet engine stops producing thrust. (hung start)

As I said before in order for those drop tanks to create a fireball you need to have the three main ingredients present and in the proper amounts for the fireball to occur. 99% of the time it's highly unlikely for it to happen.

Jeff