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At least 1,200 tornadoes develop in a typical season. They kill and injure hundreds while inflicting more than half a billion dollars in damage every year. In an ongoing effort to understand the vortex kinetic dynamics of tornadoes, specialists conduct intense research, and their methods continue to evolve. In addition to standard lab prognostication tools such as numerical cloud modeling and theoretical analysis, data are collected in the field and analyzed. Helping to gather field data is Steve Green. By supplying quality weather data from inside a tornado, Green hopes to help weather forecasters monitor the movement of severe weather systems as well as provide the public with advanced warning of their arrival and intensity.
Green chases tornadoes with his special Tornado Attack Vehicle (TA-1), which originally was a $300,000 Baja trophy truck. After significant investment from backers, it was redesigned mechanically and aerodynamically to withstand category F-4 tornado forces (wind turbulence to approximately 260 mph) while recording relevant meteorological data for instantaneous analysis by nearby mobile labs. A former stock car racer, Green represents a new breed of severe weather field research technician whose aim is literally to catch a tornado, park in the middle of it and videotape the phenomena for data analysis by lab technicians.
But turning the truck into a vehicle that will enter inside a tornado is not without its challenges. Green took his project to Parker Hannifin. The company’s mission: to develop a hydraulic system to keep the “captured” tornado’s wind from getting under the vehicle and lifting it like Dorothy’s house in the Wizard of Oz. The solution: hydraulics capable of dropping the TA-1 flat to the ground in less than a second.
Nature of the beast
The TA-1 anchors a fleet of mobile labs. Built-in safety features include a heavy-duty roll cage, bulletproof Lexan windshields, all-wheel drive, and a strategic weight/balance package. It also sports a real-time weather radar system, 8-unit video recording package, GPS satellite downlink navigation system, digital/analog phones with NexRad laptop link, and a real-time lightning display. The equipment collects vital scientific/meteorological data from within the tornado, tracks its movement, and monitors its composition from various elevations.
To help keep the car from being whizzed into the sky in heavy wind, engineers trimmed its bottom flank with an upturned steel brim calculated to turn speed into down thrust. But the best way to prevent the TA-1 from flying off into the troposphere was to keep wind from getting underneath from the start. That’s where the unique hydraulic system from Parker Hannifin comes in.
“In the beginning,” said Gregg DiGiacomo, senior systems engineer, Parker Hannifin, “Steve was unfamiliar with the dynamics of hydraulic technology – or its potential to solve the problems he had with his vehicle. He gave us an estimate of the loads and motions, and how he needed the system to operate.” Given these operational parameters, DiGiacomo drew the circuits, detailed cylinders, and manifolds to produce nearly complete drawings for Parker’s Manufacturing Division to work from. “That’s the only way to make something like this work,” he noted. “Some of the suspension loading numbers had to be recalibrated; but we managed to get it set up as best as possible given the tight deadline.”
“It’s not a matter of simply adding air shocks or building a low-rider,” continued DiGiacomo. “It was a very special application that needed an equally special design.” DiGiacomo’s prototype looked like it would work. But the true test was in the field.
DiGiacomo helped install the hydraulic system. “You don’t simply throw together a prototype machine like this and leave it for someone else to finesse,” he said. “You have to have someone who knows hydraulics backwards and forwards. That’s the only way a project like this can work. A system like this is a work-in-progress.”
Casually referred to by
team members as “The Beast,” the Tornado Attack Vehicle (TA-1) was
originally built as a $300,000 Baja trophy truck. After significant
investment from backers, it was redesigned to withstand category F-4
tornado forces (wind turbulence to approximately 260 mph) while
recording relevant meteorological data for instantaneous analysis by
nearby mobile labs.
The Parker designed
hydraulic system will drop the TA-1 flat to the ground in a split
second to prevent it from being swept into a tornado’s funnel cloud by
the updraft. (photo courtesy of Mike Hammer)
The hydraulic system
delivers 18,500 pounds of force to remove 1.5 gallons of oil from the
shocks in less than a second. (photo courtesy of Mike Hammer)
As the project proceeded, DiGiacomo and his associates spent a lot of time in Green’s fabrication shop building hoses and assembling and testing components while the team’s fabrication specialist did the actual cutting and welding.
“We had to make modifications,” DiGiacomo added, “and order special parts as we saw additional performance requirements.” Once the system was installed though, DiGiacomo’s job wasn’t over. In fact, he still continues to work with Green in fine-tuning the system as the new storm season begins. “I designed the hydraulic mechanism and know how it works,” he said, “so who better to refine it?”
Hitting the dirt
The number one factor in designing the hydraulic system was to keep the tornado airstream from getting under the vehicle and uplifting it into its funnel cloud via the dynamics of vortex kinesis. “With the hydraulic system, the vehicle still had to drive like a truck,” said DiGiacomo, “do a controlled drop, and then crank back up to 3,400 psi in short order. To do that, you have to move a huge reservoir of oil. And fast.”
The Parker-powered hydraulic system delivers 18,500 pounds of force to remove 1.5 gallons of oil from the shocks in less than a second. That’s an engineering feat in itself. But the hydraulic system also had to lock up and lower the TA-1 to the ground, yet freely navigate obstacles at high speed. Additionally, parts of the hydraulic system would experience high temperatures under the hood; so the entire system also had to be extremely durable.
The TA-1 uses redundant dc power packs to feed a substantial volume of hydraulic accumulation. Raise/Lower control valves port high-pressure oil to the front and rear actuators to vary vehicle height. At stall pressure, the actuators are capable of fully retracting the suspension to the ground. Additional valves mounted in ride-control manifolds enable the actuators to operate in a hydraulic free-flow condition while the vehicle is underway. In short, the TA-1 can hit the dirt in less than a second and return to its previous position as quickly.
Seeing what makes a tornado tick
On standby alert through the tornado season, Green’s fleet patrols the infamous Tornado Alley, encompassing Mississippi lowlands, Ohio/Missouri River Valleys and the Southeast. As satellites and the fleet’s mobilized advanced Dual Doppler radar systems detect storm buildups, the fleet is deployed and races toward the developing severe weather cell.
In the reengineered TA-1, Green and his team prepare to track a new season’s potentially explosive storms — any one of which could explode into a full-blown meteorological catastrophe. With the TA-1, Green can record internal phenomena of tornado dynamics, monitor tornado movement and check internal/external storm cell changes.
This capability translates into trackable scientific data at various elevations within the funnel cloud to determine exactly what makes a tornado tick. A special fleet of mobilized scientific weather labs, led by world-class meteorologists, aerodynamics experts, and a professional motor-sports team, backs Green’s effort. It is now possible to implement a strategic close follow/monitoring formation to record storm conditions and activities while documenting moment-by-moment characteristic changes in temperature, wind velocity, and atmospheric conditions.
Green can conduct a scientifically based project calculated to provide meteorologists with the type of real-time feedback they need to assure quantum accuracy in issuing severe-weather advisories. This information will substantially advance the understanding of tornado dynamics and provide quicker and more reliable advance warning.
Last year’s storm season spawned killer twisters that wrought devastation throughout the country’s Midwest and South. Hardest hit was northwestern Tennessee where tornadoes killed at least 27 people and destroyed thousands of homes and businesses. In Ashland City, TN, a tower that held the community’s tornado warning system was completely destroyed by the forces it was designed to warn against.
Armed with sophisticated instrumentation, field researchers are at the forefront of the ongoing effort to understand tornadoes by meeting potentially deadly and destructive storms head-on to collect scientific/meteorological data vital to improved tornado modeling and prediction. They are after clues about how to track, understand, and predict the unpredictable: the apparent randomness of tornado formation and intensity.
The purpose of these research projects is to help forecasters better understand, predict, and prepare the public for severe weather conditions. By issuing credible storm warnings earlier, the National Weather Service and affiliates could save more lives. The quantity and quality of data gathered in the field assumes critical importance.