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Presently a fueled passenger jet is a flying bomb. Is there any hope in the near future of chemically reducing the flammability of jet fuel on impact?

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    $\begingroup$ I may be wrong, but I don’t think it’s the impact which is the problem, but the fact the fuel enters into contact with fire, sparks, or high heat after an accident. And as long as we use combustion engines, we need something which can undergo combustion, in other words, can take fire. A change to completely different power sources would be needed. $\endgroup$
    – jcaron
    Apr 20 at 12:39
  • $\begingroup$ B-52Gs used to burn water, but that was a special government program. $\endgroup$ Apr 20 at 12:53
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    $\begingroup$ Jet fuel is not highly flammable like gasoline. It is basically kerosene or diesel fuel. $\endgroup$ Apr 20 at 19:31
  • $\begingroup$ @jcaron whatever the energy source is, it brings the risk of uncontrolled energy release. The safe approach all over terra firma is to use electricity or gas from an external source - because one could (1) trivially limit the energy flow and (2) easy and quickly interrupt the energy flow. We still don't have the technology to power aircraft from an external source. $\endgroup$
    – fraxinus
    Apr 22 at 7:11
  • $\begingroup$ @Organic Marble. B52 and KC135 as well as several other early turbojet engine aircraft would inject water into the engines on take off. The water raised the humidity levels of air making denser and resulting in more thrust. The B52 and Kc135 had enough water to about 60 seconds of additional thrust during the take off roll. $\endgroup$
    – Jim
    Apr 23 at 20:52

3 Answers 3

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Wrong starting point. Flying bomb it is not.

A passenger jet is way safer than a gasoline-powered passenger car in terms of flammability - both because of the fuel properties (see flash points for jet-a1 and gasoline) and because the engineering "safety vs expenses target" in aviation is WAY higher than in any land-rolling vehicle.

It is not a flying bomb. In a sense, it is a flying gas-station-sized fuel tank. Still dangerous, but not a bomb at any rate.

A vehicle needs a power source in order to operate. Should an energy source releases its energy in an uncontrolled manner, we do have a problem - no matter what the energy source is.

On the other hand, one should not expect much of improvement in the fuel properties.

  • It has to be able to burn.
  • It has to be liquid - for a number of reasons, coal is not an option in airplanes.
  • It has to have the maximum possible energy content.
  • It is already way safer than gasoline and only marginally less safe than diesel. While it is possible to ignite an open gasoline surface in air, it is pretty hard for jet fuel.

In short, the jet fuel is already almost as safe as chemically possible, with very little room for improvement.

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    $\begingroup$ Re, "coal is not an option" Aw, please! Can't we at least try? citeseerx.ist.psu.edu/… $\endgroup$ Apr 21 at 13:14
  • $\begingroup$ @Ohm'sLawman The real danger in aviation is not coal, but the nucleat power. Experiments were made, it is doable, but imho the whole idea is better left alone. $\endgroup$
    – fraxinus
    Apr 22 at 4:54
  • $\begingroup$ @Ohm'sLawman now thar I read your link, ... fluidized coal IS explosive, it is a fine coal powder in compressed air. And for whatever reason, the technology does not see much land use either. $\endgroup$
    – fraxinus
    Apr 22 at 5:04
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The only way to reduce the explosive effect of bursting a fuel tank and mixing the fuel with air is to inhibit sudden fluid motion of fuel inside the tank. In race cars this is done by stuffing the fuel cell with open-cell foam that acts like a big sponge. The fuel is capable of flowing out of this sponge by gravity fast enough to supply the peak requirements of the engine but the sponge "holds onto" the fuel during a sudden acceleration, as in a collision.

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There was an attempt at this in the 80s. An additive

ICI's FM-9, a high molecular-weight long chain polymer, when blended with Jet-A fuel, forms antimisting kerosene (AMK)

and an old Boeing 720 was filled with it and deliberately crashed by remote control.

The results were...spectacularly bad...and AMK dropped out of sight.

More info at the Wikipedia article https://en.wikipedia.org/wiki/Controlled_Impact_Demonstration

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