Fighting fire with bags of liquid

Croman tank
The modified external tank to deliver the water bags. (I’m fairly sure the gentleman said: “Say ahhhh.”)

A company in Israel has developed a system for fighting wildfires by dropping small bags of liquid from a helicopter or cargo plane. The idea is that the bags would break upon impact. Elbit Systems demonstrated their “HyDrop” system at the Aerial Firefighting conference in Sacramento, California last week, when small bags of water holding less than one liter were dropped from a Type 1 helicopter operated by Croman. Shlomo Alkaher, Vice President of the company, told Fire Aviation that other liquids could be used in the bags, such as water enhancement products or conventional long term fire retardant.

At their exhibit in the conference center we asked Mr. Alkaher if we could see one of the bags, but were surprised to hear that none were available. Later at the live demonstration at McClellan Air Force Base, we found a person who had somehow acquired a bag and allowed us to photograph it.

water bag
One of the water bags.

In a video of a test drop the company was showing in the exhibit area at the conference, it was clear that some of the bags did not break when hitting the ground, and in fact bounced. Mr. Alkaher said that the fire would eventually burn the plastic and the water would escape.

The advantage of the bags, he explained, is that the water delivery would be less susceptible to being blown off target by winds, which would also allow the helicopter to drop from a greater height if necessary.

We asked if they had conducted any tests where the product would be dropped onto a standard grid of cups, a test that is used to determine the distribution of water and retardant dropped by helicopters and air tankers. He told us no, explaining that the bags would most likely destroy the cups.

Mr. Alkaher said tests on crash test dummies determined that if a bag hit a person it would not cause an injury. The plastic bags will easily biodegrade, he said. The company has developed equipment that fills the bags near the site where they would be loaded onto the helicopter.

The company has also designed a container system that could be used by cargo planes with a rear door, such as a C-130. The containers would have a conveyer belt that would feed the bags out the door.

The video below, which has been converted to slow motion, shows the March 20 demonstration at McClellan. The camera was pretty far away so you can’t see a great deal (it helps to put it on “full screen”), but the spectators could tell that some of the bags bounced. We were not allowed to walk over and get a closer look at the drop site to see what the effects were or how many bags broke.

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44 thoughts on “Fighting fire with bags of liquid”

  1. I believe the same company tested their product using a Manitoba Cl-215 with poor results.

    1. Two questions come to mind,
      1, why would you WANT to drop from so high?, and
      2, won’t all these empty plastic bags create chaos for Type 2 helos (turbines and blades) delivering crews a few hours later?

      I have worked beside this same Helo many times when they had a conventional tank and thought they were doing a great job.
      I’m trying hard to see the benefits of this concept. It reminds me of the old aviation adage, “just because you can, doesn’t mean you should”. Is the water at least drinakable so that a thirsty firefighter could sip on an unexploded bag?!? (chuckle)

      1. Dear fire pilot,
        Your question no. 1 is enigmatic, taking into account that fire pilots actually put their lives on the line making diving runs kamikaze-style, to drop fire retardants.
        Dropping water from high altitudes should dramatically improve their safety.
        But there are other good reasons to consider using the HyDrop method instead of crazy diving runs with fire retardants – especially in fixed-wing aircraft:
        a) because it will substantially reduce the operational requirements and stresses both on the aircraft and on the aircrews.
        b) because operations from high altitudes allow work in higher winds and at night.
        c) because dropping plain water (in pellets) on fire lines may enable actual suppression of fires, rather than just delaying them in wait for the ground troops.
        d) Consequently, it substantially shortens response time to fires (leaving the ground troops only the task of finally extinguishing the already suppressed fires).
        e) because it saves the cost and collateral environmental damages caused by retardant chemicals.
        f) because with no troops on the ground, HyDrop allows a much higher level of control over the fire – even letting it burn (under control) at areas void of human presence.

        The bottom line is that HyDrop has the potential to revive the notion of putting out fires from the air, which seems to have been lost in recent years.

        1. These people with their baggies and box’s have absolutly no idea of fire behavior. When water or retardent is delivered at maxium coverage and the fire’s still burn through, slower ,but still burn through. What kind of coverage level do they think dropping boxes and baggies is going to put on the ground, a 0.5

    2. Lyle, contrary to your belief, the results in Manitoba were extremely favorable, even though the Canadian CL-215 had not been designed to drop water pellets; thus allowing it to drop only up to 2 tons. And Elbit Systems has the records and videos to prove it.
      It’s very important to note that the new method is substantially more effective in fixed-wing aircraft than in helicopters.

      1. Do you have links to official reports to back up what you are saying? I don’t think this method of delivering water or fire retardant is effective at all. This idea rates right up there with the idea that pushing pallets with huge bags of water or fire retardant out of the back of an airplane can be effective in fighting fire.

        1. Matt,
          No – there are no official reports on the drop because it was not conducted as a formal test, but rather as mere proof of concept to the government of Manitoba. I do have a short 4-camera video of the drop, showing accurate hits by the pellets of fire target on the ground, but I shall need Elbit Systems’ clearance to release it.
          Now, saying that 1 “rates right up there with” 2 only because both are numbers is not a valid argument. Dropping thousands of small charges of water with high accuracy is very different from dropping a single huge charge which does not have ballistic characteristics and can hardly be controlled. HyDrop pellets do not pose a threat to people on the ground, they spread wide enough to cover a considerable strip of fire and they are environmentally friendly (decaying in 30 days or less if not instantly consumed by the fire).
          As for effectiveness: is the current procedure of waiting for hours until the ground troops arrive, and then pushing water to them via “engines” at impossible locations any good?! Dropping water from the air as soon as fire is detected – provided that it actually reaches its targets on the ground and doesn’t turn into spray and evaporate in mid air – is a thousand times more efficient and effective.

  2. There seems to be an interest in delivering chemically enhanced water either using a bag or box. As stated ( kamikaze fire pilot) “just because………………”.
    Not quite sure where this thought of delivering water/foam/gel/retardant on fires fills a missing link in containment?

  3. How much do the bags weigh in relation to the total load, couldn’t this be better served by carrying more retardant or water?
    How much does this system cost, per gallon at loading, (put the water in the bag, transport and store, requirement fly the AC to a firebase, time consuming method to load etc) compared to water (free).
    How much space is lost due to the air spaces between bags?
    How does less water, at a higher cost lead to containment, versus more water delivered by additional aircraft at the same cost?
    Since when has aerial firefighting become kamikaze bombing?
    Have ground forces used this, attempted to throw water balloons at a fire vs, delivery via a hose?
    Is there any metric that shows it more effective than a conventional salvo drop, which is essentially what the video showed?
    Dropping water via a container was tried many years ago and failed as a method. It is hard to see this as a viable method, however forceful the sales delivery.

    1. Joseph,
      The self weight of the bags (or pellets) is negligible compared with their water contents – less than one percent! So saving it will not gain you much more water.
      The real question, however, is not how much water an aircraft can carry, but how much of it can actually reach the point on the ground where it is really needed. The answer to this question, unfortunately, is: very little. Because of “the aerosol effect”, most of the water dropped from aircraft instantly turns into thin spray, gets carried away by winds and evaporates before reaching the ground. This is why firefighting aircraft must fly dangerously low (especially considering ground obstacles and the erratic wind regimes around wildfires) in order to unload their charges; and this is exactly why fixed-wing firefighting aircraft today do not even attempt to drop water on fire lines. Instead they drop fire retardants AHEAD of the advancing fire lines, serving at best as mere support to the ground troops.
      But small pellets filled with water, weighing half a pound each, are insensitive to the aerosol effect and exhibit clear ballistic characteristics. So when dropped, aided by GPS and ballistic computers, from high altitudes, they make thousands of small bomblets that hit the fire line with great accuracy without losing any water on the way.
      For the difference between pellets and single massive charges – see my answer to Matt.

      1. I believe there are incorrect assumptions on so many levels but this one stands out.
        “most of the water dropped from aircraft instantly turns into thin spray, gets carried away by winds and evaporates before reaching the ground”…
        I guess that is the premise for the entire invention. I’m sure that a fortune has been spent on this idea.

        But REALLY, is that what you believe??? That MOST of the water never hits the ground??? All that clear wet stuff I see drowning fires must be something else altogether.

        1. Do you have ANY picture from recent years showing a fixed-wing aircraft dropping WATER ON THE LINE OF FIRE? Please direct me to such picture. And then show me “that clear wet stuff” you see “drowning fires”.
          It is a well known fact that whatever liquids are dropped today from aircraft, are released from heights of around 100 ft above ground level (AGL), and pilots are sometimes killed in the process.
          It is further a well known fact that the USFS sees the role of contracted air tankers as assistance to the ground troops, and not as independent fire fighting. This means that real extinguishing does not commence before the ground troops arrive at the scene – often taking long hours.
          As mentioned, HyDrop is intended to give back air tankers the capability of independent fire fighting, even before the ground troops arrive – thus “catching” the fire when it is still small and manageable. This is the real novelty in this method.

        2. Joseph,
          See this link showing aircraft dropping liquids on wildfires.
          I think they speak for themselves in terms of how much of the original cargo of water actually reach the ground (before even checking where exactly on the ground).


        3. With all due respect. I work with CL 215’s and 415’s all the time dropping water and they do DROWN the fires. There are so many videos of them dropping that I’m not going to bother posting them. I have also worked with Firecats that do a great job. I even worked with P3’s dropping water last year. And what about the Martin Mars??? Your assertion that the water doesn’t get to the ground is not supportable.

          The accuracy of the drop is much more dependent on the skill of the pilot than any other factor.

          The effectiveness and selection of water or retardant is dependent on the type of fuels being burned, not the quantity of liquid being dropped.

          No amount of liquid can take the place of a man with a Pulaski.

          1. Joseph,
            The activity of aerial firefighting is not in the website. It is too small and too young to be included. But the website gives you an idea of Elbit Systems’ capabilities in general.

        4. I’m sure you know better than me. I’m not a firefighting pilot, not even a pilot. But I have talked to some of them. I roughly know (from our Manitoban friends) how things work out in Canada, and it’s very different from the US. Both due to availability of water reservoirs and due to weather conditions.
          All I’m saying is give it a chance. We shall prove with time, via real-scenario experiments that the HyDrop Method actually works.

  4. I know that I am old and resistant to change but this seems like a “less than clever” idea to me. Less product delivered, higher cost, a bunch of trash left on the ground just doesn’t spell success in my book.

    1. Tom,
      I must disagree with you.
      In fact, MUCH MORE product is DELIVERED (as opposed to unloaded), at SAME or LOWER cost (can do without chemicals – only water), “trash” left on the ground – if not consumed by the fire itself – is bio degradable and decays within 30 days.
      But now look at the real benefits. First and foremost: shorter response time to reported fires (early start of actual firefighting operations from the air); elimination of dangerous diving maneuvers by firefighting aircraft; possible operations even in poor weather and AT NIGHT; dramatic increase in flight safety due to the high altitude; less demanding flight profiles (wear & tear) to the aircraft, and less stress on the aircrews; lower fuel consumption and insurance costs; better CONTROL of the fire; savings on ground troops labor, equipment and human wear & tear; to name just a few…

      1. You may be right that more water gets to the ground, then in a “normal” tank drop. I don’t have any statistical data to verify that though.
        You are saying there would be decreased costs, that I find hard to fathom. It may be cheaper than retardant, but not in the application that you used it in he video. Water is for all intensive purposes free. The system in the video would require more flight time to get to the location that would have to be set up to refill, plus the cost of the plastic product. Not to mention the costs of the extra personnel to man the operation. So your theory that it is cheaper with regards to helicopters is void.

        You say there would be shorter responses times, quite frankly, how? Your not making an aircraft fly any faster, and we already established that a helicopter would most likely have to fly further to be loaded with this product.

        Next, You are saying that it will be safer because it can be dropped from a stable high altitude. How is it going to be accurate from altitude? I doubt that the accuracy would be very good from a higher altitude, which would equate to less product on target, requiring more drops, which would make it more expensive. Also limiting flight time, limits risk and exposure to the pilots.

        1. The term “cost” cannot be weighed on its own merit. One must consider cost-effectiveness, i.e. the total cost in relation to the achieved results.
          Now, if a wildfire can be put out earlier and faster by using the Hydrop technology (because aircraft can start extinguishing operations before the fire has time to grow and intensify, and even before ground troops arrive), then the overall operation costs drop significantly, simply as a result of their shorter duration.
          To load water pellets on the aircraft, the idea is to have a container holding filling machines at the nearest airfield, where they will fill enough “bags” when the aircraft is on a sortie to suffice for the next one. Indeed this arrangement involves some extra cost; but as mentioned, the total cost is a function of the time span and the total number of sorties required to finish off the fire; as well as other important factors such as labor wages, fuel, insurance and aircraft wear & tear.
          For hit accuracy see my response to Joseph.

      2. As a fellow inventor, pilot and fire fighter I would never discourage a person from pursuing an idea. Look for your wildfire niche. Example, a timber fire burning in a steep canyon (twenty to thirty acres) with a subdivision above. No immediate or safe access. Accurate delivery of your product after dark (other aircraft are on the ground) should not be an issue. The objective will be to put enough retardant (bags) between the fire and the homes above. When I first started flying crop dusters at night people said I was crazy, probably right.

    1. Not so fast Kimosavi. During the Viet Nam War rocks and small boulders where slid out the back of C 119s to open up the forest canopy. After herbicide application if the denuding was too slow the rock and boulder approach would yield instant results. I think ice is out.

    2. Believe me: you don’t want to get hit by an ice cube dropping from a thousand feet! Not even if it’s much lighter than half a pound.
      Plus, making the ice cubes, as opposed to packing water in bags, is a lengthy, energy consuming, expensive process.

  5. I’m not completely sold on the idea that if hit by one of these “bags” no injuries will incur. The talk of higher altitudes of dropping them increases the injury factor ten fold! The higher the more velocity they gain. Also the foreword speed from the aircraft with height……. To me this is going to kill people! Even if not being hit by the bag, the surrounding environment ie. snags, widow makers, ect. Then you throw in the night factor on top of this. That’s a whole different beast. “Controlling” a fire from air? I don’t think this will ever be a sole idea. You will need to back it up with folks on the ground. Also thaving to have a site to fill bags the crew to fill bags instead of scouting a dip site close by. I understand dip sites are not always close by. But when there is one readily available turnaround time is by far cheaper. It becomes even faster. when you have a rotation of aircraft when it permits you can get work done! Instead of the “bagcraft” having dropped. disengaging. returning to HB. Filling. Then Finally returning. turnaround is going to be ineffective. Either way I believe an innovation like this is going to have some things to truley figure out. I really would like to see proven fact these “bags” will not harm ground personel. Again this is just my opinion being a grunt on the ground.

    1. The velocities and impacts of dropped bags on the human body have been extensively tested using real NASCAR dummies with sensors, at every possible angle. Consequently, a package of half a pound (200 grams) has been certified to be fully safe for humans even in the maximum possible speed. Note we are not talking rigid bodies here; above a certain speed the bags simply burst out upon impact, causing no damage at all. and BTW: they don’t reach infinite velocity…
      Other than that, I really don’t think we can agree on everything at this stage. I’m just saying give it a chance. Personally I believe it can make a great difference in how wildfires are fought.

      1. I like the fact that there has been testing done on nascar dummies. Is there documentation from that? That one could possibly review. Understandably no one will fully agree. There is a lot of speculation and unanswered questions that will need to be seen. Kudos to them for trying new things!

        1. All the relevant documentation will be presented to the US Forest Service as part of our application to certify HyDrop as a legitimate method of aerial firefighting. Obviously, as part of the process we intend to pass the system through whatever tests and demonstrations are required by the USFS.

  6. Yigal,

    You are communicating with the people who will be seeing the application used, not with the people who are going to be buying (contracting) for your product.

    Whether you know it or not, you have fallen victim to the Sarah Palin effect by attempting to address each of your critics opinions. The public viewed Sarah as constantly having to defend herself, which made her reactionary in the eyes of the voters. You have a niche. You are not going to change the system.

    Airtankers were first theorized in the 20’s and incorporated in the 50’s. It took 30 years for that idea to “take off”.

    A truly professional company that has a shot at pulling off a feat as remarkable as the one you are proposing would not have only thought of how the product will work, but how it will be marketed, communicated, demonstrated, and certified.

    Here’s a tip, Get a PR firm, come up with a marketing strategy, sell the idea, to the appropriate audience, then sell the product.

    1. CM, thanks for the insight.
      At this point I’m not trying to make any sale – just spread the new concept around. And in the process I hope to learn the objections that we may encounter and prepare for them.
      Thanks again.

  7. CM is right on target! Many of the folks who post comments are wildland fire fighters with collectively hundreds of hours in the “real world”. I would play close attention to their messages. Work your niche, try not compete with what is already working well. Remember sunset, no access, no personnel on the fire, huge threat during the next burning period. As mentioned as an ag pilot if I’m going to work all night spraying I don’t start after dark. Establish your mission while there is some light and transition into the darkness. With todays G.P.S. systems this will be the route an aircraft will follow (like and instrument approach) for delivering your pellets during the night.

    1. Johnny, thanks.
      I do appreciate your advice and will take it under consideration.
      Interestingly, you mention “spraying” while the very core of our message is “bombing”.

      1. Yigal,

        If your intent is “bombing” a point target at night using something like a level lay down attack, not dispersing the payload to cover an area, you have some serious work to do with respect to how to identify aim points, assessing bombing effectiveness, and adjusting subsequent aim points. You need a bombing system.

        What is your planned drop accuracy for various delivery modes? What is the effective radius of the drop as function of release altitude and airspeed? That would be the bombing counterpart of determining area coverage and density for “spraying” operations. Accuracy and effective radius will largely determine your drop parameters and tactics.

        Will you use visual or system deliveries? If visual, what thermal imaging system do you plan to utilize at night to see and designate aim points? If a system delivery is planned and you intend to use GPS aim points, how will the aim point coordinates be determined and how will they be adjusted for follow-on deliveries?

        If your core message is about night bombing, you may find you need to produce something like a night attack helicopter to deliver the payload.

        1. Bean,
          If you look at the performance of Elbit Systems’ stock on the NASDAQ exchange, and study the “Areas of Business” on its website home page ( you’ll understand that the company (with annual sales of US$ 3 Billion) possesses not only the know-how relating to all the relevant technologies, but also the skill, talent, personnel, resources and expertise to live up to its promised performance.
          The questions that you raise are all serious and valid. They will be addressed in the framework of HyDrop certification for usage in the US by next-generation air tankers contracted by the USFS.
          The general direction however, is indicated above in this page.
          The word “bombing” relates to the controlled release of thousands of half-a-pound “bomblets” made of water-filled biodegradable pellets. They will be dropped from altitudes of 500 ft or higher using sophisticated tools such as GPS, INS, Ballistic Computers, Pilot Goggles’ Line-of-Sight (LOS) and thermal imaging – all integrated into a single unified HyDrop system.
          Obviously, these “bomblets” will be dropped in a calculated way on the line of fire as figured by all these tools. At a later time digital communication may be added between the fire boss and the air tankers, using data links and moving electronic maps.
          I hope this gives you the picture.

          1. I went to the company website and could not find one word about this program, nor mention of any of the people mentioned as associated with the company in the Board of Directors, Management, or Committee or Investor Relations areas. Can you point me to where the system and its products are described on the Elbit webpage?

  8. Mr. Manor if you are looking to spend lots of money I have two patents pending, internal tank for a Chinook and the Watchman (external home protection device). Of course you would want to advertise with Wildfire Today. Bob mentioned coverage levels. C 130 aircraft, conveyer belt, five seconds, 2000 gallons U.S., retardant line1000 feet long, width maybe 30 feet. multiple “stair step” drops at night above the fire. Much Success!

    1. Mr. Coldwater,
      No, we are not looking to spend lots of money – only as much as needed to take us where we want to be.
      Elbit’s intent is to leave the design of aircraft tanks (internal and external) to its US partner. Isolair is the selected partner for the design of helicopter tanks, as demonstrated in the Sacramento Conference. You may approach them with your ideas of internal tank for the Chinook. But frankly, it’s a little early to speculate on where we shall be in a year from now. We’re just the new kid on the block, and have a lot to learn.

  9. Yigal,

    Perhaps the reason your idea has has been met with so much doubt and criticism in this forum is because you use phrases like “diving runs kamikaze-style” and “crazy diving runs” to describe the flight profiles of aerial firefighting aircraft, or maybe it’s because you are asserting that your pellets will “put out fires from the air.” Your ignorance of what actually takes place in the flight environment and how fires are extinguished is not only glaringly obvious, it’s both undermining your argument and offending your audience at once.
    I fully welcome your intent to make our line of work safer and more effective. I even welcome your intent to make some money. The ill-advised comparison of fire pilots to suicidal, communist war mongers, however, should be checked at the door.

    1. DiggerT, thank you for the eye opener.
      Yes, this must be it. I must have used, unintentionally, language which is too judgmental, maybe even offensive to some people. I never meant any disrespect to pilots. They are definitely doing their best with the tools put in their disposal, but my words could have been misinterpreted. As I already mentioned above, we are the new kid on the block and still have a lot to learn. I’ll definitely take your comment under advisement.

  10. I’m not clear from this story what advantage the “Hydra Drop” system has over the traditional water bomber, retardant air tanker or helicopter helitanker. It would seem that new ground support infrastructure would be required to “bag” and “load” water into an aircraft that doesn’t currently exist in the market and there will have to be some quantitative cost/benefit advantage over the free drop of water, water (with gel) or retardant to catch fire agency interest.

    During the 2010 Mount Carmel wildfires in Israel a wide variety of international aircraft were mobilized to try and contain the fire including Trush Commanders, CL-215s, CL415s, Q400s, Air Tractors, IL-76s and the Evergreen 747. Some aircraft dropped at too high an altitude to be effective and others dropped in a “free for all” fashion because there was no integrated fire management system in place including trained air attack officers.

    The Ontario Ministry of Natural Resources, the world’s oldest aerial fire fighting agency (established 1924) conducted extensive drop tests using water filled paper bags from fixed-wing DHC-2 Beavers floatplanes and Bell 47G helicopters in the early 1950s. While the bags reached the fire on the ground with little water loss, the logistics of “bagging” water at remote field locations was a major draw back. Further efforts by the MNR saw probes attacked to the floats of DHC-3 Otters that could fill “roll tanks” with water while skimming the surface of a lake. This marked was the beginning of the “gallons per hour” water bomber concept which has been refined over the past 60 years on the DHC-2 Beaver, DHC-3 Otter, DHC=6 Twin Otter, PBY-5 Canso, Martin Mars, CL-215, CL-415 and AT-805 FireBoss aircraft.

  11. I have personally seen the Elbit precision drop technology work first hand and it puts the water pellets directly on a given target and the target does get very wet! These guys know what they are doing and I believe this technology does have a place in aerial firefighting. It is by no means a total Replacement for all forms of aerial fire suppression but definitely a worthwhile tool to have as a supplement to traditional suppression tactics.

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