Aircraft

Unpowered cargo gliders on tow ropes promise 65% cheaper air freight

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Autonomous vortex-surfing Aerocarts could increase a given aircraft's payload capability by 2-300% when towed behind it, reducing air freight costs by as much as 65%
Aerolane
Autonomous vortex-surfing Aerocarts could increase a given aircraft's payload capability by 2-300% when towed behind it, reducing air freight costs by as much as 65%
Aerolane
Aerolane's prototype cargo gliders both still have engines and propellers installed at this point, but have a custom autopilot system designed to surf the lead plane's wake vortex for maximum efficiency
Aerolane
Sure, Aerolane will make a military version
Aerolane
The simplest, lightest possible airframe: an unpowered glider chock-full of cargo, with autonomous glide and vortex surfing capabilities
Aerolane
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A West Texas company says it's found a remarkably simple way to slash air cargo costs as much as 65% – by having planes tow autonomous, cargo-carrying gliders behind them, big enough to double, or potentially triple their payload capacity.

The idea certainly isn't a new one – payload-carrying gliders were towed toward combat zones in World War 2, full of troops and/or equipment, then released to attempt unpowered landings in the thick of things – with widely variable results, particularly where stone-walled farms were a factor.

More recently, the US Air Mobility Command tried flying one C-17 Globemaster III some 3-6,000 ft (900-1800m) back from another, "surfing" the vortices left in the lead plane's wake – much like ducks flying in formation – and found there were double-digit fuel savings to be gained.

But Texas startup Aerolane says the savings will be much more substantial with purpose-built autonomous cargo gliders connected to the lead plane with a simple tow rope. With no propulsion systems, you save all the weight of engines, motors, fuel or batteries. There'll be no cabin for a pilot, just space for cargo and the autonomous flight control systems that'll run them.

These "Aerocarts" will be pulled down the runway by the lead plane just like a recreational glider. They'll lift off more or less together with the lead plane, then stay on the rope throughout the cruise phase of flight, autonomously surfing the lead plane's wake for minimal drag and optimal lift. And they'll either land right behind the lead plane, rope still attached, or eventually possibly be released at an ideal spot so they can make their own descent, potentially landing at an entirely different airstrip than the lead plane.

The latter would require some regulatory wrangling, but otherwise, according to Bloomberg, Aerolane believes it shouldn't be treated much differently by the FAA than regular ol' recreational gliders. It remains to be seen how the FAA will feel about this.

Aerolane's prototype cargo gliders both still have engines and propellers installed at this point, but have a custom autopilot system designed to surf the lead plane's wake vortex for maximum efficiency
Aerolane

The company is, however, already flying two "automated tow cargo glider" prototypes, as shown in the video above, and has been doing so since 2022. The first is a converted 1,000 lb Pipistrel Virus, the second is a rather spunky-looking Velocity SE canard pusher, that's also been converted for the job. Both run Aerolane's own autopilot system, designed specifically for efficient vortex surfing.

Both still have engines in them, but Aerolane is working with the FAA to get authorization to start building aircraft without powertrains, using lightweight materials. At that point, it'll look to build a 3-ton cargo glider, then a 10-ton version.

The simplest, lightest possible airframe: an unpowered glider chock-full of cargo, with autonomous glide and vortex surfing capabilities
Aerolane

The company has raised about US$11.5 million in seed funding to get things started, and has set a target date of 2025 for "initial availability." It doesn't have any early customers signed up yet, but once it gets custom prototypes benchmarked, the idea of "the speed of air at the cost of ground" could well get freight operations interested, even if these tow-gliders are sure to drop jaws everywhere one takes off or lands.

Source: Aerolane

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16 comments
Ken
This is really an old idea revisited. I recall reading an encyclopedia from the 1930's which featured an aircraft towing 3 or 4 passenger gliders so it could drop them off at points en-route
WONKY KLERKY
Wot could possibly go wrong?

Do suggest remote control to override the auto be mandatory.
Obviously a pilot jockey to the glider would be even better.
TechGazer
If the tow plane can take off with this loaded glider and its own load, isn't it overpowered? If it can't carry its own cargo capacity while towing, wouldn't it be more efficient to add winglets to reduce the loss from wing vortices? Why are planes not already bearing winglets to improve efficiency...which would leave no vortices for these gliders to get extra lift from.
Ryan Waldron
Unless they have found a way to violate the laws of thermodynamics, they are full of #)_$. The lead aircraft will just expand all the fuel needed to lift the towed aircraft. Unfortunately, society at all levels is made up by 99.5% complete morons....so the company will bilk a few billion and the wealthiest among them will walk away with the lion:s share while those that do all the work will loose their jobs.
Robt
@TechGazer Winglets are not in and of themselves an aerodynamic advantage.
They only increase the aerodynamic efficiency of a wing that is already in production which can now be improved by the addition of winglets due to currently available computational analysis, and do so much more cheaply than a complete wing redesign.
In such cases they effectively increase the wingspan - simple.
Other reasons for winglets, (in commercial aircraft for example) can also relate to such mundane issues as maximum allowable wingspan for parking at the gate of an airport.
Kpar
It has been well understood that ducks and geese fly in a "V" formation so that the wake turbulence can be used (by the birds) to improve efficiency and extend range. The idea is a sound one. I note that TechGazer wonders if the tow vehicle isn't overpowered (Robt's answer to him about winglets is entirely accurate!). I disagree, the ability to "throttle back" the engines is used by all airlines when they encounter a strong tailwind, but still wish to remain on schedule. And, on multi-engine aircraft, it is feasible to actually shut down some engines after achieving altitude. And that brings up a question: would the glider be pressurized? If the cargo was not sensitive to pressure differences, the glider could be made MUCH lighter. And if the cargo WAS sensitive, would they simply fly at a lower altitude?
byrneheart
I suspect the redundancies required of manned and pressurised aircraft, cargo or passenger carrying, mean that there is sufficient power in existing planes. The progressive lightening of the load from the moment towed aircraft begin to generate lift, and their relative lightness to begin with due to fewer over engineering requirements, and the vortex surfing benefits, may mean that initial fuel and cruising expenditure are significantly less than
a simple doubling or whatever of fuel costs.
paleochocolate
@techgazer winglets don't remove vortices entirely, they just move them to the edge of the winglets rather than the edge of the wings.
paleochocolate
@Ryan Waldron tell that to the geese. It's not about power expended during takeoff, it's about fuel savings in flight. The longer the route, the more efficient the transport.
spyinthesky
This is an interesting concept even if I have doubts over its practicability. I defer to others on aerodynamic characteristics around this but some questions arise.
I remember reading about 30s/40s efforts around this concept and in particular developing wartime glider operations. The problems and dangers were considerable and there was little room for error when operating the bomber glider combo. I read first hand accounts during early experiments and pilots nearly lost their lives the effects were so pronounced. Indeed many did during operations.

Now technology and science have come a long way since but then the aims and expectations are a lot greater too. I note even in recent times that crashes have been put down to wake effects of a leading aircraft upon one following behind even under freak conditions some time after the I ual aircraft has passed. Clearly there are limits indeed between aircraft landing and taking off acknowledging this potential problem. So what possible safety level could be guaranteed in a scenario of this type. What airports and flight paths would authorities deem safe enough to exploit the system? It’s matters like that as Concorde found that will dictate the practicality and profitability beyond the technical predictions. And the problem is it’s chicken and egg the legal environment won’t be tested until the technical environment becomes clear making such a system probably near impossible to get off the digital drawing board as whatever the technical reassurances there will always be doubts over innate safety I suspect.