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.