A different type of towbarless tractor promises to reduce fuel consumption, cut carbon emissions and protect aircraft from FOD damage while taxiing planes all the way to the runway.
We had a first-hand look at the Taxibot towing system during a special demonstration put on for the media to show off the new vehicle that promises to take a plane from gate to runway with its engine’s switched off.
“Someday you can say you were a passenger of the very first jet towed by a Taxibot,” said Ran Braier, Taxibot project director for the Israel Aerospace Industries Ltd., as we sat inside an A320, waiting for a turn to walk into the cockpit.
To be sure, the concept has already passed a number of operational tests since Braier first walked into Lufthansa LEOS headquarters and purposed the idea some four years ago.
“I was skeptical at first,” remembered Gerhard Baumgarten, director of sales and marketing, speaking at a press conference held at the airport. “We had tried to develop ideas like this before, but nothing had come of it.”
What eluded Lufthansa engineers was that the pilot was used to being … the pilot. And if that meant the engines needed to run to power the plane as the pilot taxied to the runway, well so be it.
In essence, the crucial difference between standard towing procedures and “something else” meant that there would be essentially no difference to the pilot who wanted full control of the plane.
During his presentation, however, Braier showed Baumgarten a movie in which engineering students built a model to convey how sis semi-robotic tractor concept could put the pilot in command by means of a mechanical interface that would be “transparent to the pilot.”
Which is how we found ourselves sitting aboard a plane with no engines on the Monday before Thanksgiving, Nov. 19 at Chateauroux Airport, located several hours drive west of Paris.
“The Taxibot is more like a new aircraft in terms of its technology,” said Antoine Maguin, chief operating officer of the TLD Group, which built the Taxibot prototype. As many as 100 engineers worked on this one vehicle since TLD agreed in 2009 to ultimately manufacture the production vehicles.
“You can image that when you have only five engineers working on a GSE project,” Maguin joked, “you know it’s going to be a very big project.”
Although we were nominally the guests of TLD, the Taxibot concept has picked up quite an international pedigree during its R&D phase, including such well-recognized aviation industry names as Airbus and Lufthansa LEOS.
FIRST GLANCE
At first glance, the Taxibot doesn’t look that much different than other towbarless tractors. Like those conventional tractors, the Taxibot lifts up the plane’s nose landing gear before, say, pushing back the plane.
But a closer inspection reveals the “something else,” in fact, two major components – an interface mechanism that clamps on the wheels, which is in turn mounted on what Braier calls a “rotating turret. Those two elements are what leave a conventional tow behind:
Pilot In Control: Yes, the Taxibot does have a driver at the wheel. The driver’s main job, however, is chiefly dedicated to safe operations. And, of course, someone has to be on deck to drive the Taxibot back to its next rendezvous.
Once the plane is pushed back, the pilot is given complete maneuverability and, in effect, should feel no difference between plane and Taxibot during the tow.
“The Taxibot’s speed control is similar to a car with an automatic transmission put into drive,” Braier explained. “When the pilot releases the plane’s brakes, the Taxibot starts to move.”
Meanwhile, the pilot steers using the tiller in the flight deck, which transfers the commands to the Taxibot’s wheels by way of the interface that pivots on the turret. And not just a minor move to the left or right. The Taxibot’s tires each independently move, keeping the Taxibot in perfect alignment with the plane even during wide turns, avoiding any disasterous jackknives. (Earlier tests at Lufthansa had the plane/Taxibot going in Figure 8s.)
About the only time the pilot is not is command is when an algorithm kicks in to keep the Taxibot at a safe, steady rate of movement without undue stopping and starting while waiting in line with other aircraft.
Longer Tows: The “rotating turret” description doesn’t quite do justice to the Taxibot’s engineering since it also acts like a pendulum protecting the plane’s delicate nose landing gear during acceleration and stopping. And when the pilot does apply the brakes, the plane’s own braking system absorbs the force rather than the nose gear.
“The plane brakes itself,” said Fadi Anbouba, vice president of sales and service for TLD America, “which is exactly what those brakes were designed to do. By protecting the nose gear that allows us to tow the plane a much longer distance than with a conventional towbarless tractor.”
BIG SAVINGS
And with that “dispatch towing” opportunity comes billions saved in fuel and emissions otherwise burned each year just to move aircraft to runways every year.
During a briefing, Braier outlined the economic and environmental benefits of the Taxibot system.
By the end of the decade, planes using their own power to taxi on the ground will cost airlines around $7.3 billion in annual fuel costs. That number could be cut, Braier said, to less than $3 billion using the Taxibot system.
With no assist from the aircraft’s engines, the Taxibot uses hybrid diesel electric power to drive motors in its wheels and produces a negligible 132 pounds of emissions during a tow. To make the point perfectly clear during our demonstration, the A320 that took us for a ride had its engines removed (although added ballast on each wing equaled the weight of those missing engines.)
Braier also estimated the Taxibot has the potential to significantly reduce carbon emissions. Just the fuel saved alone by using the Taxibot represents 22 million tons of emissions.
In addition, an aircraft with engines running is particularly vulnerable to FOD damage. Braier said the Taxibot system could cut down on the $700 million in FOD damage projected by the end of the decade since half of that damage is done when the plane is either at the gate with engines on or taxiing under its own power.
The Taxibot is expected to come in the narrow-body aircraft model we saw demonstrated in France, and another model to handle wide-body aircraft.
The narrow-body model is expected to be priced at $1.5 million and $3 million for the larger model. IAI believes that each vehicle could handle about 20 aircraft daily. Simulation and studies conducted by IAI show that little or no modifications are required by airports, and that there is no overall impact on taxiing time when operating a mix of aircraft taxiing either with or with the Taxibot. There are no modifications that need to done to aircraft to accommodate the Taxibot.
TLD plans to focus initially on making the narrow-body model and anticipates them to enter the market in 2013. Certainly, a prime candidate would be airlines operating from major European airports where tough environmental mandates, such as carbon taxes, are in place.
Later that same week our media demo took place, senior reps and test pilots from various airlines and ground companies including Lufthansa; KLM; British Airways; China Eastern Airlines; China South Airlines; Federal Express; Air France; United Airways; WestJet Aeroport de Paris; and Swissport International, traveled to the airport to evaluate the vehicle.
