Figure 1. (a,b) Representations of the proposed firefighting system based on the use of a swarm of collaborative UAVs. (From the research)The person who was awarded a patent in 2017 for describing a system of drones that could be used to drop liquids on wildfires wrote a paper earlier this year with two other authors that claims to have determined how many drones would be needed for suppressing a small section of a fire.
The patent, #WO2017208272A1, awarded to Marco Ghio, is quite vague and does not supply any technical details. It says that instead of applying fire retardant or water in a conventional manner, a “rain” concept would be used:
Dropping small quantities of firefighting liquid or drizzling it over the fire, and its subsequent spreading on a large area instead of in a concentrated manner. This method, both theoretically and experimentally, is acknowledged as being particularly effective, whereas, on a practical level, it is effectively used in domestic and/or industrial firefighting systems.
Diagram from the patentIn the United States fire retardant dropped from an approved air tanker is applied at coverage levels ranging from 1 to 9 gallons per 100 square feet, depending on the situation. It is not clear what coverage level “rain” would produce.
Drawing from the patentThe patent specifies that drones would transport the liquid in removable containers. Upon returning empty to the mobile base the containers would be autonomously replaced with full containers, along with a charged battery if needed.
The drones and the other equipment would be transported in standard metal shipping containers which would be strategically positioned. The system would include “a control unit for the coordination of missions, the flight paths to be followed, and the selection of the ideal drop points optimized according to the environmental conditions.”
Details about how all of this would be accomplished are not specified.
The patent and the research paper written by Mr. Ghio, Elena Ausonio, and Patrizia Bagnerini assumes that the cargo capacity of the drones would be 5 to 50 liters (1 to 13 gallons), much less than currently carried by helicopters (up to 3,000 gallons) and fixed wing aircraft (up to 17,500 gallons) that routinely fight wildfires.
Their analysis (below) takes into account wind speed, flame length, the length of fire line to be suppressed, and the dead fuel moisture. It indicates that about 75 linear meters (246 feet) of the fire’s edge could be extinguished with 120 drones each carrying 20 liters (5 gallons) or 80 drones carrying 30 liters (8 gallons). The vegetation is assumed to be grass or brush, but not timber. The example below assumes that the wind speed is 20 km/hour (12 mph) and the dead fuel moisture is 18 percent. A moisture content of 18 percent for 1-hour and 10-hour time lag fuels is quite high for a very active wildfire. It should not be very difficult to suppress a fire under those fuel conditions.
Figure 4a shows the linear meters of fire that can be arrested by using the firefighting system. For example, approximately 70–75 linear meters of active front can be extinguished with 120 drones each carrying 20 L or with 80 drones carrying 30 L. Assumptions are that the wind speed is 20 km/hour and the dead fuel moisture is 18 percent. (from the research)Our take
In my opinion the most difficult part of using drones to assist firefighters would be applying the retardant or water at the exact location where it can be useful. That is difficult enough when you have good communication with ground personnel, adequate aerial supervision, and experienced highly qualified air crews in helicopters or air tankers.
I don’t think the principle of “rain” in the application of retardant or water from dozens or hundreds of drones is a thing, at least when you’re talking about drones that can just carry a few gallons of water and must have the batteries replaced every 20 minutes. The suppressant still has to be delivered in a timely manner in a quantity and at the location where it can be useful. Maybe when drones are carrying 50 to 100 gallons of water, and the technology improves for placing the retardant on target, it might be useful in very remote areas when the fire is very small, less than 1/10 of an acre, and the wind speed does not exceed 5 mph.
Rain Industries is working on an Unmanned Aerial System (UAS) that could carry up to 400 pounds of cargo, or 50 gallons of water.
Drone Amplified, the developer of the IGNIS prescribed fire system currently being used for aerial ignition, and Parallel Flight Technologies, have received a $650,000 grant from the US Department of Agriculture to support further development of a large-scale Unmanned Aerial System (UAS) for prescribed fire. Parallel says their hybrid gas/electric UAS can carry 100 pounds for up to two hours, numbers that are much larger than battery operated drones. When paired with the upgraded aerial ignition payload under development which will hold and dispense 3,500 incendiary spheres, it will have eight times the payload carrying capacity of drones being used today, and ten times the flight duration.
The paper was published by MDPI, which is food for thought.
9 Comments
During any discussion of aerial assets, I keep coming back to the reports this last summer of how all helicopters, including the ones with night flying capabilities, and all air tankers were grounded on the Caldor fire because of high winds and low visibility due to smoke. If conditions are clear and calm enough for drones to work, wouldn’t they also be good enough for existing air tankers to work?
I think this would a great question posed to a 40-75 hour Private Pilot with some basic meteorology behind him/her. I think their answer would be a resounding YES. Swarm of drones doing the work of VLATs, LATs and SEATs…..weren’t they on the way to solving that problem about 2 yrs ago when those “swarms” were running around CO and NE? Conspiracy Theory right there…..testing swarms of drones under the cloak of UFOs!!
Sounds like that patent office is now accepting proposals from high school science fairs.
About 2010, Lockheed held a “think tank” at College Station, Texas, as they were thinking the new Obama administration was going to gut the military budget, and they wanted to see what devices they could sell to the fire world. Long story short, but they had an 800 gallon drone for dropping water/retardant. The room had several Ops, Air Ops, IC’s, UAV folks (yes, even back then), etc
We all mulled about mixing drones with ATGS/ASM’s, helicopters, Airtankers, etc. I think Lockheed knew where this was going, but let us all ramble until we were done. Then Doug P, the Lockheed guy, asked “What if we only flew the drones at night?” You could have heard a pin fallas the room went dead silent.
So, how about a fleet of 6 each 800 gallon drones, in endless loops to the fire, drop, back to Airtanker Base, reload, all night while the fire is least active (and firefighters and other aircraft are not endangered)? Could the above crew run the calculations on that scenario?
Bob S, sometime the most sensible, practical, simplest, safest, effective approach to a problem gets lost in our efforts to build better mousetraps. Was never a supporter of aerial tactical ops at night because of the increased risks to pilots and aircrew. This obviously simple approach to day/night ops could be a game changer. UAVs configurations for tactical and support operations at night can be more versatile and safer.
There is out of the box thinking and then there is out of the box thinking. I have been involved in several U.S Patent endeavors. Congratulations to those involved in this concept. Is this a U.S. patent?
It’s an international patent.
Hats off to those pursuing this new UAV endeavor. Hopefully they will have an appreciation for the dynamic and challenging environment aerial resources operate in on wildfires.
Concept sounds promising but after 30+ years as an ATGS, I’ll wait and see if they can have success.
That’ll be like waiting in line during Basic Training…….the very last man/ woman due to other duties and details, had about 5 minutes to choke down their food in 3-5 minutes or like waiting in a line for Christmas shopping….I’ll be waitin!!
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