How it Works
The FTF system uses a laser beam shot from a distance to cut leaves off the trees, making a fire control line, which is an area where the fire won't spread into, containing it in the area the fire control line surrounds. This allows for a safe and easy suppression of the fire.
The system does not require any material to be loaded (as water or chemicals) and thus can work continually, allowing for a more efficient work, and less fuel waste for the refill trips familiar in the traditional methods of suppression.
Cutting the leaves off the trees stops the firefront in two primary ways, addressing two of the three elements in the fire triangle.
The fire triangle models the necessary elements for combustion and self-sustained fire: Heat, Oxygen and Fuel.
Using water to suppress fire is one of the best approaches. The water both deprives fire its fuel and reduces the heat. But when there is a strong wind, dropping water onto the fire can prove to be tricky up to impossible. The wind just blows the water into unexpected directions, and the water does not arrive at its target. Another issue arises when dealing with extremely big fires. In some cases the temperature is so high that water dropped into the fire area decomposes and instead of acting as a battling force for fuel or heat, it acts as a new oxidizing agent, as the oxygen is released from the water. In other words the water dropped into the fire just makes it stronger.
The FTF system uses laser to cut down the leaves, which bypasses the problem of strong wind. Cutting the leaves off the trees then tackles both the fuel element and the oxygen one in the fire triangle:
1)FUEL: It eliminates the fine fuels that normally advance the firefront at the treetop level. This is mostly the firefront that spreads the wildfire rapidly and unpredictably.
2) OXYGEN: Packed on the ground, the green leaves make it harder for the firefront to advance on the ground level as well.
We shall expand on those two points separately.
By cutting the leaves off the trees, the FTF system will reduce the Canopy Bulk Density (CBD), which was pointed as a significant factor controlling the sustainability of treetop fire.
The Van-Whagner Threshold is a CBD limit under which the fire can't sustain itself. So by reducing the trees' CBD to below this threshold will stop the propagation of treetop fire, and will force the firefront to the ground.
This is essentially removing the fuel part in the fire triangle from the treetop area.
Fires usually start and spread in dry fine fuels which ignite increasingly larger size classes of fuels. If fine fuels are reduced or missing, a fire may not ignite or spread.
Fine fuels presence in the flaming fire front in a forest stand determines the fire spreading rate (fine fuel of width smaller than 1/4 inch in diameter).
Additionally, the green leaves that will have been cut off the trees will stack on the ground, the place to where the fire will be confined. Both the water percentage contained in these leaves and the way fact that they will stack on will help suppressing the fire on the ground level.
Stacking the green leaves on top of the dry leaves that cover the ground makes for a much harder fuel for the fire to ignite.
The stacking itself reduces the oxygen supply significantly, reducing and slowing down the firefront.
So having removed the fuel for the treetop fire, and reducing the oxygen for the ground fire, the FTF system will allow for an easy suppression of the remaining fire using traditional suppression techniques such as dropping water or chemicals on the fire directly.