Planning to pour cold water on the towering infernos

As cities prosper, land values increase and architects design ever-taller buildings, packing more office, hotel or living accommodation into the same ‘ground footprint’.

Sometimes there is a real need to build high-rise blocks for this reason, or sometimes cities embrace high-rise developments in order to look more ‘modern’, aping the most successful megalopolis cities like New York or Tokyo, even where there may perhaps be little or less apparent need to do so.

But even in Dubai, high-rise development allows easier proximity to particular areas, allows greater hotel and office capacity exactly where that capacity is needed, and helps to prevent an unmanageable sprawl.

High-rise living affords its occupants city-centre convenience and breath-taking views, and the latest buildings are often well appointed and full of every possible modern convenience. Many offer prestige and luxury.

But there are drawbacks and disadvantages, too.

In the event of any emergency, evacuation can be problematic and slow, and fire, in particular, can be especially hard to tackle, as was shown after the World Trade Centre’s twin towers were attacked on September 11 2001.

The fires raging high above ground level were almost impossible to tackle and many were trapped above the flames, or were unable to evacuate before the buildings collapsed, leading to massive loss of life, as well as the destruction of the buildings themselves.

But as well as highlighting the difficulty of fighting fires high in very tall buildings, 9/11 also emphasised the difficulty that can be encountered in rescuing people on higher floors. Many of those who died in the World Trade Centre did so because they were unable to descend past the raging fires, and some died when they chose to jump from the towers in the face of encroaching smoke and fire.

Before 9/11, casualties in skyscraper fires had been relatively light – the 1946 Winecoff Hotel fire in Atlanta killed 119 people in the 15-floor building, while the Las Vegas MGM Grand fire that occurred on November 21 1980 killed 84 people in the 23-storey resort. Another 97 died in the Dupont Plaza Hotel fire in Puerto Rico on December 31 1986.

But when the World Trade Centre Towers were hit, 2,312 people were killed, demonstrating the potential for disaster in really tall buildings (both towers had 110 floors, and were more than 1,360ft tall, excluding roof mounted antennas and spires).

While sprinkler systems and strictly enforced and rigorous fire regulations can reduce the likelihood of serious fires, emergency services face a real challenge in fighting any fire and reducing loss of life above a certain height – above which conventional fire fighting equipment, ladders and hoses cannot reach.

This ‘danger height’ is sometimes defined as the seventh floor of a high-rise building, or is sometimes classed as being above the 11th floor. This disparity is, in part, due to the effect of new telescopic devices like the Aquamast aerial fire-fighting system, a 7-13 metre mast which can be fitted to small fire trucks, trailers, and other specialist vehicles, and which can be deployed in narrow streets where conventional fire engines may be too wide or may not carry tall enough ladders.

Helicopters provide an even better solution to the problems of both fire-fighting and rescue at greater heights, though specialised equipment and techniques are needed.

In conventional helicopter fire-fighting operations, helicopter ‘tankers’ typically drop water vertically on to a blaze – using under-slung Bambi buckets or fixed tanks. For high-rise fire-fighting, drenching a building from the roof down may be ineffective, and there is a need to deliver water horizontally into the seat of the fire, ideally using a water cannon.

Dubai hosts the world’s tallest building, the 2,732ft Burj Khalifa, as well as the 1,053ft Burj Al Arab (the fourth tallest hotel in the world). With 911 completed high-rise buildings – 88 of them taller than 180 metres (591ft) and 18 of them above 300 metres (984ft) – and 363 new skyscrapers under construction in 2012, the Emirate has an obvious interest in high-rise fire-fighting and in the use of helicopters in this role.

At the request of the Dubai Police Air Wing, Tangent Link is hosting a unique conference at the Dubai Helishow, focusing on high-rise fire-fighting. At this event, helicopter and fire-fighting equipment manufacturers will debate and explore the issues with representatives from international emergency services, as well as from civil and government helicopter operators.

The emergency services in Dubai face a wide range of choices when it comes to equipment, when it comes to helicopters, and when it comes to operating models.

What the Americans call helo high-rise fire-fighting and rescue is not just about equipment, as Larry Collins from the County of Los Angeles Fire Department (LAFD) will demonstrate at the conference. He will describe how the LAFD air operations unit has established a dedicated fire-fighting and rescue team.

The air operations unit was established in 1962 with a single Bell 47, subsequently growing to a fleet of larger turbine-powered helicopters, with Bell 412s, Sikorsky S-70 Firehawks and, most recently, AgustaWestland AW139s. These serve as both air ambulances and as fire attack resources, operating from Fire Station 114 adjacent to Van Nuys Airport.

An alternative operating model will be described by Radik Asylbaev, the head of the aviation department at the Russian Federation’s Ministry for Civil Defence, Emergencies & the Elimination of Natural Disasters (EMERCOM), presenting Moscow as a case study for the use of helicopters in an urban environment.

Fire-fighting helicopters come in all shapes and sizes but so far relatively few have a water cannon capability. Of those that do, the largest is the Erickson S-64 Aircrane, a development of the Sikorsky S-64/CH-54 Skycrane incorporating more than 300 design changes and improvements.

The Aircrane incorporates a 25,000lb load capacity, allowing it to carry a 2,650gallon (10,000litre) tank with microprocessor controlled tank doors that allow eight different coverage levels, automatically adjusting for airspeed and giving a flow rate that matches the selected coverage level.

The tank can be filled with water, a foam/water mix or chemical retardant. Refilling can take as little as 45 seconds using a flexible snorkel to pump up water from sources as shallow as 18 inches (45cm).

Almost uniquely among helicopters, the Aircrane combines the delivery capacity of fixed-wing tanker aircraft with the manoeuvring capability of the helicopter, and with the ability to hover, making it possible to use a targeted water cannon.

Exactly such a water cannon has been added to the Aircrane in recent years, able to propel a stream of water or foam mix from 150-200 feet at a rate of 300 gallons per minute. A constant stream can thereby be maintained for up to eight minutes.

In addition to operating its own fleet of Aircranes, Erickson is marketing the type to other customers, including foreign fire-fighting services.

A number of alternative water cannon are available for smaller fire-fighting helicopters. One such is offered by Simplex (which manufactures the composite fire-fighting tank for the Aircrane and designs similar tanks and fire attack systems for a number of other helicopter types). Simplex entered the fire-fighting market in the early 1990s, initially designing a tank system for Russian Helicopters’ Kamov Ka-32. 

More recently, Simplex has adapted its third-generation aerial cleaning system (ACS), designed for the routine cleaning of power lines and insulators (significantly enhancing power transmission and generation) into an aerial fire-fighting system, aiming the new hydro foam cannon at the growing requirement for fire-fighting for high-rise buildings.

The ACS system already used a power-wash boom in conjunction with high-capacity belly-mounted water tanks, and the fire-fighting derivative adds a new compressed air/foam system, developed by Heliap Aviation Products. The chemical-reaction pressure system allows delivery of 1,000 cubic feet per minute of a water/foam mixture (0.4% foam) at 500psi, giving a range of about 120ft.

Like the ACS’s power-wash system, the water cannon boom extends past the main-rotor disc, preventing the water/foam mixture from dissipating in the downwash, and maintaining a concentrated ‘stream’ with which to fight fires. The hydro foam cannon can also be used to apply dry foam to the outside of the building to prevent any fire from spreading upwards.

The roll-on/roll-off Simplex model 516 fire attack system was developed for the Eurocopter EC 225 and was demonstrated on a Chinese Haifei H425 from 2009.

The system adds water/foam/retardant tanks, a 23hp Honda power pack (consisting of a motor, pump, and generator), a 6.7 metre high-strength carbon fibre boom (with an aerating spray nozzle) which is power-operated from the fore-and-aft ‘ferry’ position to a perpendicular operating position.

The system also includes a FLIR system and two laser range finders, one for the pilot and one for the fire fighter operator, which measure distance between the aircraft and buildings or other hazards, even in the densest smoke.

A rival to the Simplex system is offered by the German IFEX company, which developed its Impulse fire extinguishing system (IFEX) in 1994.

IFEX is based on high-pressure, high-speed jets of smaller quantities of atomised micro water droplets (1-30 litres) using specifically adapted water cannons. These fire ‘water bombs’ (also known as impulse bullets) that can achieve speeds of more than 400km/h (allowing much more precise aiming), and whose droplets break down to about 100 microns, dramatically increasing the surface area of the water fired, and thereby increasing its cooling effect. This naturally reduces the quantity of water needed to extinguish a given blaze.

Originally developed for use on a ground-based vehicle, the IFEX cannon was quickly adapted for aerial use, and especially for fighting high-rise fires. Initially, IFEX designed installations for the Eurocopter AS-350B2/B3 Ecureuil, and the Kaman K-MAX.

The Ecureuil installation paired an attached 300litre water tank with dual 18litre intruder cannons, while the K-MAX installation has a pair of 25litre IFEX 3000 cannon and a choice of two FAA-certified 2,650litre u-shaped tank systems, bolting directly to the load beam.

One system is an aluminium/carbon fibre tank designed by Kawak Aviation Technologies, while the other is the all carbon-fibre Isolair Eliminator II tank. Both systems use a hydraulically-powered hover refill pump and feature computer or electrically-controlled door systems.

The Ecureuil is limited by being a single-engined helicopter and by the small capacity of its tanks, and the relatively modest 50metre range of its cannon, while the K-MAX is not EASA certificated, and is not routinely or commonly operated or supported outside the USA.

These factors led IFEX to search for a further platform, settling on the Kamov Ka-32A11BC, integrating the 25litre dual cannon with a 75metre range. The initial conversion was undertaken by Helifor in Croatia, and Russian Helicopters and EMERCOM were heavily involved in the programme.

The Ka-32, with its coaxial main rotor, is powerful and agile, and its lack of a tail rotor gives relatively compact dimensions, useful for operating in urban environments. The aircraft can carry up to five tonnes of water or retardant.

Examples of the type have already been delivered to the Emergency Situations Ministry of the Republic of Kazakhstan, and to the Public Security department of the Central Administration of Ordos city (in China’s, Inner Mongolia autonomous region).

For rather smaller scale emergencies Jaycar Electronics now offers the ultimate executive toy for those in the aerial fire-fighting business in the shape of the Hydra – a radio controlled helicopter equipped with a water cannon capable of shooting a stream of water over a range of about one metre – perfect for drenching colleagues or at least for mildly dampening their clothes.