Aircraft

In-ground aircraft towing tech promises fuel savings and less CO2

In-ground aircraft towing tech...
The Aircraft Towing System has been in development for the past 10 years
The Aircraft Towing System has been in development for the past 10 years
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The Aircraft Towing System has been in development for the past 10 years
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The Aircraft Towing System has been in development for the past 10 years
Inside the prototype channel – note the monorail down the middle, and the electrical rails along the sides
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Inside the prototype channel – note the monorail down the middle, and the electrical rails along the sides
The prototype ATS setup should reportedly soon be functional
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The prototype ATS setup should reportedly soon be functional
One of the ATS pullcars with the dolly mounted on top
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One of the ATS pullcars with the dolly mounted on top
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Ordinarily, airliners have to run their jet engines in order to taxi along the runway – this uses a lot of fuel, plus it generates a lot of carbon emissions. A new in-ground electrical towing system, however, offers what could be a much more efficient and eco-friendly alternative.

Known as the Aircraft Towing System (ATS), the technology is currently being developed by Oklahoma-based firm ATS World Wide.

The system incorporates long trench-like channels that are installed length-wise down the middle of existing taxiways and aprons (or built into new ones) and then covered with two steel plates, one on each side. There's a 1.5-inch (38-mm) gap between those plates, creating a slot which runs the entire length of each channel. That gap is covered with a split rubber gasket, in order to keep foreign objects from falling through.

Contained within each channel is a motorized monorail device called a pullcar, which is powered by electrical rails running along the sides of the channel. Via the slot between the plates, the top of the pullcar is attached to another device called the tow dolly, which sits exposed on the surface of the runway.

One of the ATS pullcars with the dolly mounted on top
One of the ATS pullcars with the dolly mounted on top

Most of the time, each pullcar/dolly unit sits out of the way. Once an airliner has landed or is ready to depart, though, the unit moves up to the aircraft's front wheels. The pilot then runs the plane's engines just long enough to move the wheels onto the dolly.

Chocks on the dolly subsequently rise up to hold the wheel in place, and the pullcar kicks in to push or pull the aircraft along the tarmac as needed. Once the plane has been towed to where it needs to be, the engines are run once again to move the wheels back off the dolly. In cold climates, heating elements in the channels are used to keep the slots from icing over or getting clogged with snow.

The whole system is automated, so pilots don't need to steer their aircraft along the tarmac, nor do control tower staff need to remotely control the pullcars. This should minimize the chances of planes colliding with one another on the ground, or simply getting in one another's way. In fact, researchers at Oklahoma State University have reportedly calculated that use of the system could increase aircraft throughput at airports by up to 30 percent.

That said, ATS can be manually overridden if necessary. Because the wheel chocks on the dolly are ramped, the wheels can run up and over them if the plane's engines are used.

"Right now when an aircraft comes in, it's typically handed off between four different people between the time it touches the ground and it gets to the gate," ATS World Wide CEO Vince Howie tells us. "And 80 percent of the time, the pilot's driving the aircraft on his own, without any directions. We're going to take that system, and totally automate and optimize it."

Inside the prototype channel – note the monorail down the middle, and the electrical rails along the sides
Inside the prototype channel – note the monorail down the middle, and the electrical rails along the sides

Because the system is modular, airports that are on a budget could initially opt for just the pushback sections, which are used to push or pull planes out from the departure gate and onto the runway. Currently, fuel-burning, human-driven pushback tractors are utilized for this task. ATS is presently finishing up a 358-ft (109-m) prototype pushback channel at Oklahoma's Ardmore Municipal Airport, which we're told should be operational within three to four weeks.

It should be noted that the system does face some competition, mainly in the form of airliners with motorized front wheels, and an unmanned electric towing tractor known as the TaxiBot. The former requires modifications to be made to aircraft, however, plus it makes them heavier and thus less fuel-efficient when flying. The latter, on the other hand, needs to have its batteries recharged once every several hours, and may obstruct runway traffic on its way back from taking planes out for takeoff.

Since a complete ATS setup would cost about US$150 million, airports would definitely require a means of recouping those costs. Howie suggests that such airports could charge a landing fee to airlines, which would be equivalent to about 50 percent of the cost of the fuel each aircraft would save by using the system. Additionally, the airports could sell their carbon credits to other companies. All told, he believes that operators should see a return on their investment within just two years.

"Eighty percent of the commercial fleets are 737s or A320s," says Howie. "They burn about nine gallons (34 L) of fuel per minute during taxi. The average taxi time in the US is between 16 and 27 minutes. At large airports, you'll have over 800,000 movements per year. So if you take that nine gallons of fuel, times 16 minutes, times 800,000, times whatever the price of fuel is of the day, it turns into real money really quickly."

You can see an animated demo of ATS in action, in the following video.

ATS

Company website: ATS

View gallery - 4 images
17 comments
17 comments
paul314
Seems to me that $150M would pay for a heck of a lot of battery charges by an electric tractor (robotic or otherwise). And that's also thousands of tons of CO2 emissions for the concrete and steel used to put all the tracks in the ground. And then even more for every time someone decides to change the airport's ground traffic pattern so they have to rip out old track and install new...
TechGazer
The arguments against the Taxibot sound like they're desperate to put down their competition. An extra Taxibot or battery pack sounds cheaper than construction and maintenance of that underground channel. Obstruct traffic? Surely that's a simple programming problem. If vehicles can navigate busy roadways without obstructing traffic, avoiding a few aircraft should be trivial. Nice idea, but I expect the Taxibot concept ends up being economically superior.
Trylon
Now all they have to do is extend the concept to the runways to create a land-based version of aircraft carrier catapults so airliners can take off with less engine thrust and thus less noise and fuel consumption.
Derek Howe
The wheel tug seems like the better option. This would have a lot of initial up front costs, but I guess once it's installed, your done. Time will tell which option is best.
Wayne Morellini
This is a nonsense. Design the wheel to use electro magnetic induction to power it to drive it to the terminal. Then all you need is to insert the wiring. Simplifying again, you can have a rail system affect, that turns on where the aircraft is and turns the wheels or drags it to the destination. Third, have a simple electric motor affect, using the above devices from the planes electric reserves itself. Fourth, using breaking in the wheels on landing to generate electricity to enough to then in turn, turn the wheels to taxi to destination. Fifth, maybe then look at using a fly wheel to break assist and store the energy. Seventh, convert over to diesel electric using waveplate motors (90% efficient, but wherever diesel is another issue, but battery precharge is also possible for part flight duration, enough for short flights becoming long flights in future as 10x batteries come out, on shuttle basis). The latest executive prop plane design will move at well over 700km/h, at much better figured than a business jet. Expanding to long haul regional flights with larger bodies, and newer turbine. Diesel, and turn up shuttle, to drastically decrease airport costs and safety while increasing passenger usage and turnover due to convenience of reduced queuing and wait times for no pre-book turn up and access travel.
That's engineering! Do I get a job at Space X?
highlandboy
Twin engined planes have to keep one engine operating at all times for internal power & A/C. If engines are off where is the power coming from to restart the engines? Fuel consumption at idle is about 75% of cruise. So unless there is a retrofit of a power coupling, savings would be round half the projected.
highlandboy
All thermo-mechanical engines have a operating temperature. Taxi time allows the turbo-fan engines to reach that operating temperature. Take-off places the engine at maximum stress so it is important to ensure that the operating temperature has been reached. While taxi time is greater than the minimum warm up time, the engines would need to be operational for at least part of taxi. This further reduces fuel/CO2 savings.
Bernd1991
Hmm. Seems like a Tesla CyberTruck could be capable of doing this.
A Tesla Model X is already capable of it: https://www.inverse.com/article/44847-tesla-model-x-pulling-boeing
The CyberTruck Tri-Motor will have 14,000 pounds of pulling capacity. That's about 3x as much as the Model X. Thus, if the X is already capable to some extent, the CyberTruck might be in every condition, all day long.
Bricorn
Trylon
Unfortunately, also with a lot more G's that a commercial plane, or its passengers could tolerate.
Sean Reynolds
No! Just use battery powered taxi vehicles that are above ground! You actually create more friction by having this vehicle surrounded on three sides, and the tolerances on the concrete become problematic. What do they do when these channels flood? Do we still take off when its raining? What about freezing? No! Just use battery powered vehicles above ground like space x uses to secure the rockets after landing. There is no need to install all of this infrastructure for something that can be accomplished so easily above ground.
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