by Marc Mullis
editoraff@agairupdate.com
Occasionally a new product hits a market that is just not yet prepared for it. About twenty years ago, Wipline Float Manufacturing Company located in South St. Paul, Minnesota installed a pair of their DeHavilland Beaver amphibious floats on one of their customers’ Ayres Turbine Thrushes. These floats were designed to allow the aircraft to skim the surface of a body of water filling the hopper “on the go”. This customer had hopes of finding work for the aircraft in the aerial firefighting business. The idea never really got off the ground and the product faded from view.

About twelve years ago, along comes Leland Snow with his Air Tractor AT-802 design. Immediately, Leland and Bob Wiplinger, President of Wipline, began having conversations about installing amphibious floats on the AT-802. Since this aircraft was designed from the start as a firefighting tool, it seemed to both men to be a normal evolution to equip the AT-802 as a dual-use scooper-tanker. As with any undertaking of this size, the project did not come to fruition immediately. But several years down the road, the results of their brainstorming efforts resulted in the Fire Boss.

An AT-802 on fixed gear is a pretty imposing piece of equipment on its own. When it sits on top of a pair of Wipline 10000 amphibious floats, it becomes a monster airplane. Standing over sixteen feet above the tarmac, this is one ship you do not want to fall off. Displacing 11,500 pounds of water, the floats are basically Twin Otter equipment that has been shortened to match the Air Tractor airframe.

The scooping mechanism consists of retractable stainless steel probes located on the inside-underside of the pontoons. They are simple, low drag and easily changed or repaired. The pilot can pre-select the amount of water to be scooped. The scoop control panel is located on top of the instrument panel at eye level. The panel also contains information on angle of attack, foam transfer system, auto bilge and water-warning system, TOT/ Torque gauges and audio/visual overpower warning system and probe position indicators.

The position of the panel allows the pilot to keep his eyes outside the cockpit while monitoring the parameters of the scooping process. Optional 35-gallon foam tanks in each float add to the standard eighteen-gallon fuselage tank. One great advantage of the float configuration over the flying boat design is the ability to jettison the load while scooping.

All of the engineering work on the Fire Boss is done in-house at Wipline in Minnesota. Bob Wiplinger, an aeronautical engineer, employs four engineering technicians and three Designated Engineering Representatives, one flight qualified and two structural. Bob’s son, Charlie, is a part of the engineering staff. The mating of the floats to the airframe is also accomplished at the Fire Boss facilities. Modifications to the AT-802 airframe include increased wall thickness on ten crucial joints of tubing on the superstructure and addition of ventral fins both under the tail and on top of the horizontal stabilizer. Additional welded fixtures can be requested with an initial order from the Air Tractor factory. The addition of the sub-panel and all associated electronics is also accomplished in Minnesota.

Operationally, the Fire Boss has proven itself over fire. In the hot 2003 fire season, the new tool proved its worth in British Colombia, Canada, and the dry interior of Spain. Conair, the Canadian company which first operated the Fire Boss during the 2003 fire season, found that using the aircraft in conjunction with two of its fixed-gear AT-802s was highly successful. All three of the aircraft would be dispatched at the same time, but since the Fire Boss is approximately ten knots slower, it would be the last to arrive at the fire. On his way to the incident, the pilot would look for suitable scooping sites. After making his retardant drop, the pilot could then begin scooping operations. During the entire season, scooped loads averaged six-minute intervals. This equates into a total of 7500 gallons of water per hour on target.

The aircraft also utilizes the Air Tractor Fire Gate. This computer-controlled system allows the pilot to select the amount of water or retardant to be dropped per pass. He can also select the coverage level from one-half gallon up to six gallons per 100 square feet with a full salvo. The gate system is constant-flow insuring the same amount of material on target for the length of the drop pattern.

In its current configuration, the Fire Boss is limited to 200 gallons of fuel and 650 gallons of water with its initial scooping operations. As the fuel is burned off at the rate of eighty gallons-per-hour (575 pounds), the water load is steadily increased to the maximum load of 820 gallons.

Vortex generators on the leading edge of the wings have reduced take-off speed from eighty to sixty knots. This is a great improvement, as it significantly decreases take-off, landing, and scooping distances. Lower scoop speeds allow operations from smaller lakes. An additional benefit is the reduction of drop speed from 105 to 90 knots. Lower drop speeds result in better accuracy and a pattern with less shadowing. Shadowing occurs when the forward speed of the material being dropped causes it to adhere to only one side of the vegetation.

Bob Wiplinger and his team are currently seeking certification of a Fire Boss with a Honeywell TPE 331-14 engine rated at 1,650 horsepower. Having flown several hundred hours myself in the Pratt & Whitney PT6A-67 AT-802, I can only imagine what the extra 300 horsepower will do for performance. With the PT6 installation, take-off distance at gross weight over a fifty-foot obstacle is listed as 3,250 feet. Scoop profile over fifty-foot obstacles is currently 6,900 feet. The Honeywell installation will greatly reduce these distances while increasing the rate of climb. Flight tests are currently underway and certification is expected soon.

There are now nine Fire Bosses in the field conducting operations with orders in place for twelve more. All of the units sold so far have been in foreign countries. Several states, including Minnesota, Wisconsin, and Idaho, have expressed an interest in the dual-purpose firefighter, Idaho is expected to lease one during the upcoming wildfire season. So far none of the U.S. federal agencies have expressed an interest in the Fire Boss. This may change in the future as the big amphibian continues to demonstrate its abilities. Simple systems, ease of maintenance and high reliability are important virtues for an airtanker, the Fire Boss has them all. Compared to any available alternatives, the $1.8 million USD sale price becomes very attractive.

Scoopers can do amazing things when the proper circumstances are in place. I once worked a fire in Washington that was very close to the Columbia River. A Canadair CL-215 working on the fire was splashing it every three minutes. That’s twenty loads an hour compared to my two loads an hour from a tanker base forty miles away. He made a huge difference with the water supply being so close.

Leland Snow and Bob Wiplinger have teamed up to design a product that seems has a market ready to accept it. The Fire Boss combines two tried and proven components into one efficient firefighting machine. I can hardly wait for the day that I get to work a fire alongside one, or even better, in a Fire Boss!