Eelectric on the long haul? No problem for an Airbus A340, at least on the ground and at Frankfurt Airport. This is ensured by the new battery-electric Goldhofer Phoenix E aircraft tow tractor from Lufthansa Engineering and Operational Services. The mighty vehicle crouches flat on the asphalt. The cabin protrudes far in front of the front axle, the two rear wheels are on the side of the bay, which will later accommodate the nose wheel. When empty, this layout with a top-heavy load distribution makes for a somewhat restless handling. The Phoenix charged its Akasol batteries with a total capacity of 165 kWh with 50 kW direct current. The dispatcher has already sent the flight order to the tablet computer in the cockpit: a so-called southern tow, empty from the Lufthansa hangar across the airport to the parking position of the jet at the future Terminal 3, then with the aircraft in tow back to Gate A 62 at the terminal 1. Makes about eight kilometers – the long distance mentioned.
Achim Kahl starts the vehicle, and the 17-ton, 240-kW giant hums and rolls away. The working conditions made the Phoenix E popular from the start, says Kahl. Because compared to its diesel counterparts, the new one is not only emission-free, but also extremely quiet. The elimination of engine noise of over 80 decibels is a bonus. Charging takes place between uses: park at the charging station, connect the cable, go for a coffee. This is in contrast to the Goldhofer diesel-powered tractor, which looks almost identical on the outside and only needs to be refueled every two days. The liquid energy reserve is filled up in 15 minutes.
The medium size 2 tractor is a pioneer in the 21-vehicle tractor fleet. Because no other towbar-free tractor from the ground service provider runs on nothing but electricity, only hybrid technology has existed so far. The Phoenix E relies entirely on electric traction for the first time. The vehicle was delivered to the largest German airport at the end of 2021. Intensive testing in operation began even before the public premiere in March. After the first three months, the Lufthansa subsidiary is satisfied: “The average workload can be compared with the diesel version of the tractor,” says Sven Meyenburg. The 48-year-old industrial engineer accompanied the introduction of the new tractor.
Battery tow tractor at the airport
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The Phoenix E takes on up to 24 towing jobs every day, mainly between parking positions, gates and maintenance hangars. This is the typical portfolio, since the airport operator Fraport is responsible for pushing back the aircraft before departure at the gate for almost all machines. Lufthansa Engineering is only responsible for this for Lufthansa’s Boeing 747s. “We are constantly collecting data about the operation,” says Meyenburg about the pioneering application. It’s about making efficient use of capacities and technically optimizing processes. It would be ideal if, in the future, the dispatchers could read the battery charge of the tractor directly in the system. This is particularly important if several battery-powered tow tractors are to be used in parallel in the future and the vehicles are to be distributed over their routes depending on their charge level.
The journey to the parking position is quick, despite the complex traffic on the apron. The tug has to stop several times and let planes pass – the planes have priority. Arriving at the future Terminal 3, Achim Kahl circles the Phoenix E once around the A340 and checks the condition of the aircraft. The electric tow tractor maneuvers its tail around the double wheel at the bow of the jet, grabs it with a hydraulic gripper, lifts it and can now move the aircraft over the apron at up to 32 km/h. The vehicle now weighs 11.8 tons. The aircraft’s center of gravity is above the large, three-piece main landing gear. The additional weight in the back ensures proper traction and braking power. This is a design advantage of all towbarless tractors. In addition, they are significantly faster with a load than the tow bar tractors.
After a few hundred meters you have to wait a moment. The Phoenix E and Airbus A340 gently come to a standstill in front of the center runway at Frankfurt Airport. Three machines take off to the east. Then the tower clears the way, the follow-me vehicle with the distinctive checkered rear rolls away, with the tractor directly behind it. Again and again, the driver and the tower communicate via radio, the battery charge is now at 80 percent. On average, the tractor consumes 16 kWh per operating hour. How much fuel is consumed on a single trip depends on many factors, so the tractor is no different from the car. For example, there are drivers in the team who use the energy reserve particularly sparingly through clever recuperation. The fact that the air conditioning in the large glazed cabin comes on in warm weather should have less of an impact on fuel consumption in this performance class.
With the battery tow tractor, the electrification of flight operations in Frankfurt has taken an important step, the airline is certain. Lufthansa Engineering and Operational Services intends to order the second vehicle of this type before the end of this year.