Boeing wants to fight wildfires with a howitzer

M198 155mm howitzer

Above: M198 155mm howitzer. Photo by Armyman1989.

We have seen a lot of wild ideas about devices that inventors think could suppress wildland fires, such as a fire extinguisher bomb, a mine-clearing missile to build fireline, a fire truck that would suppress a forest fire without using water, a disposable air tanker, and 2,000-pound containers of liquid dropped from aircraft. Some have been awarded the unenviable “lame-ass idea” tag.

On July 28, 2016 the U.S. Patent Office published a patent application submitted in 2014 by Boeing for an artillery shell fired from a 155mm field howitzer that would deliver fire retardant or another fire suppressing liquid to a wildland fire. Each shell would hold between 1.57 and 3 gallons.

The howitzer shells would release the fire retardant either by an explosive, or by mechanically opening the shell. The release of the retardant would be at a pre-determined time, at a pre-determined altitude, at a pre-determined acceleration, at a pre-determined location, at a pre-determined temperature, at a pre-determined pressure, or at a pre-determined distance.

The application claims:

The gun delivers the fire-retarding material with high accuracy, at a high rate of delivery, at a reduced cost over typical fire-fighting methods such as airplane or helicopter release or ground-based fire-fighters. The fire-retarding material may be delivered continuously or intermittently for long durations, regardless of darkness, weather conditions, or intensity of the fire with reduced risk to those fighting the fire. Some guns may deliver the fire-retarding material within 15 feet of a target at a 15 mile range.

The application gives examples comparing the use of the howitzer and helicopters to deliver water or retardant to two fires that had initial sizes of 28 and 883 acres.

Our calculations based on the basic data in Boeing’s patent application determined that the 28-acre fire would need between 1,663 and 3,178 howitzer shells depending on the capacity of the shells used, 1.57 or 3 gallon versions. The 883-acre fire would require between 71,333 and 140,127 shells.

The application does not describe how many howitzers Boeing envisions being used at the same time to extinguish a fire.

We certainly are no expert on the specifications and use of military artillery, but a quick look at Wikipedia found that the M198 medium-sized, towed 155mm howitzer has a sustained rate of fire of two rounds per minute. Let’s say you had 5 howitzers available for the 28-acre fire, making 10 rounds per minute possible. They would need to continuously fire for about 3 to 5 hours. The 883-acre fire would require 120 to 233 hours (5 to 10 days). And that is assuming that the fire would spread very little during those 3 hours to 10 days. If you had only one howitzer, it would take 5 times as long.

Boeing did not discuss in the application the effects of the noise from firing thousands of rounds from 155mm howitzers. Imagine trying to sleep in fire camp while howitzers are firing.

Boeing says the debris from the shell casing will either “degrade”, “or degradation may not be necessary as the material will be environmentally inert”.

There are many issues with the concept of using artillery shells on a fire. Here are a few:

  • Unexploded shells. Would the fire be off limits to firefighters for days or weeks until it goes out and bomb disposal teams can be deployed to examine the area to declare it safe? Would the bomb disposal teams have to be firefighter qualified? Would it even be possible to find unexploded shells, or might they be buried in the ground?
  • Would land managers be comfortable with the debris left after thousands of the shells explode or come apart?
  • How long during and after the bombardment would firefighters be prevented from entering the fire area?
  • How far would the howitzer sound travel? From how far away would neighbors complain about the noise?
  • The patent application assumes that retardant applied from the air can suppress a fire. Generally, it can’t. Under ideal conditions retardant can slow down a fire, enabling ground-based firefighters the opportunity to move in and actually put it out or stop the spread with water or by removing fuel along the perimeter. If firefighters are not available to take advantage of the temporary slowing of the fire, aerially applied retardant is usually a waste of time and money.

The application mentions that the shells could also be used for nuclear plant fires and hazardous material emergencies. If a howitzer shell fired from miles away is the only way to deal with a nuclear meltdown, then that might be a feasible use for this idea.

The bottom line.

We award the use of howitzers to suppress wildfires a lame-ass idea tag.

Thanks and a tip of the hat go out to Bob and one other person.

Typos, let us know HERE. And, please keep in mind our commenting ground rules before you post a comment.

Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire. Google+

13 thoughts on “Boeing wants to fight wildfires with a howitzer”

  1. Sign me up as a member of the Boeing team! I graduated from the US Army Field Artillery Officer Candidate School as a qualified Arty Officer, and so should become a top-level Boeing Exec for this new program.
    This idea is almost as cool as the one we were exposed to when I was at the Missoula T&D Center: the scientists at the Lawrence Livermore National Lab wanted to use “fuel air explosives” to stop fires. Blow up a bomb filled with gas above a fire, and it sucks all the oxygen out of the air. No oxygen = no fire, right. People and animals on the ground: just collateral damage!
    Bill – you need a new classification for ideas likes this: “REALLY lame-ass ideas”.

  2. It might get a bit expensive. Artillery shells are expensive, propellant charges cost a lot, you have to tow the large cannon around, have a well trained crew to fire it. And how do you explain “friendly fire accidents”? But what the hell it’s only money. A very lame ass idea. Water balloons from airplanes, let’s go there.

  3. Some one st Boeing must’ve been sitting at their computer and
    WACK! the Good Idea Fairy hits the subject in the back of the
    head. Subject exclaims “what a good idea.”
    As she flies away in a cloud of Cigar smoke and fairy dust.
    “My work here is done-now back to NIFC…”

  4. The present way to fight a fire is to suffocate it ether through the use of water or fire retardant. We need to look at the molecular structure of a fire. If we find a substance that can interrupt the reaction that cause fire it could be spread ahead of the fire preventing surrounding material from igniting.


    1. You just defined long term fire retardant used by air tankers.

      From Wildfire Alberta:

      A long-term fire retardant contains a chemical, which alters the combustion process. The active ingredient, salt, permits pyrolysis at a lower temperature and promotes the formation of H2O, CO2 (water and carbon at once) and char, at the expense of flammable gases.

      Wood itself does not burn; rather, the gases that are produced through pyrolysis ignite when the “flash point” is reached, and provide the additional heat required to produce additional flammable gases.
      Other ingredients in the fire retardant formulation provide cooling (e.g. water) and smothering or insulating (e.g. clay/ guar gum) action. Examples of long-term fire retardants are, Fire-Trol¨931, and Phos-Chek¨ LV-R.

      1. Thanks for the info. Just wish it was more permanent for if it was there would never be fires in the same area. Sigh.


        1. “Permanent” fire retardant has also been tried. Air tankers that dropped sodium calcium borate were first used on the 1956 Inaja Fire in San Diego County. It was quickly discovered that this chemical sterilized the soil, preventing any vegetation from growing for years, and by 1957 it was no longer used. However, the term “borate bomber” still lingers on 60 years later.

          1. If we could just clearcut the vegetation, pave it, paint it green and coat it with permanent fire retardant, all of our wildland fire problems would be history. So would our quality of life in the West.

  5. This goes back to a fire I was on in Idaho were the army fire fighters were from an artillery battery and wanted to bring in a howitzer for morning briefing to announce the meeting. That was also “super lame ass”

    1. Let’s all give 3 cheers for the Military-Industrial Complex, as President Ike called it in his 1960 Farewell address.

  6. This has potential guys! Sign me up for the howitzer hotshots. We could dot the whole west with crews 30 miles apart and use the old board game strategy of battle ship n let them fly! Bet that fire on the Colorado boarder would be better off with a couple howitzer crews.

  7. “The patent application assumes that retardant applied from the air can suppress a fire. Generally, it can’t.”

    ^And that, people, is why the stuff’s called ‘retardant’ instead of ‘extinguisher.’

    A friend of mine thinks that someone at Boeing came up with this idea during the paintball game at a company retreat.

  8. There must be some some millennials, or other such goons, at Boeing R&D who have been play too many unreal combat games online.

    The capability of Field Artillery units to consistently put rounds on target is without question. Aka: “King of Battle!” However “walking rounds” along a fires edge is worthless if the rounds are not sufficiently effective, environmentally low impact and the whole show economically viable.

    I’m always open to new methods of fire suppression but this is a lame ass idea.

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