Tow-plane pilot for gliders is a dangerous profession. A simple mistake by the glider pilot can kill the tow plane pilot, with not enough time to react. I saw this happen in person once (https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/G...). Gliders and towing them is neither easy nor safe.
In gliding, tow upsets are pretty common and, in rare cases, can be fatal. An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority (ability to pitch up or down) which leads to accidents like this. This video does a good job explaining explaining the root causes and potential dangers (https://youtu.be/5cpqFzhM9dY?si=J7GxP1dI9Xopy3xu). Also read the comments from testimonials from other glider pilots.
This is my biggest concern with this concept as well. Towing things is challenging because the tow plane's center of gravity can change drastically depending on the forces on the glider it is towing -- if the glider deploys its spoilers / crabs in a crosswind / gets in your wake turbulence you're not going to be able to predict how it changes your CG (and your control authority) without training or experience. Also, with gliders, the tow plane is traveling at around 60MPH to 90MPH, with a decision window of 2-3 seconds. Commercial planes travel at ~500 MPH... The concept seems like a hard sell to the pilot unions. I bet they've thought about this though.
> An out-of-position glider out can _easily_ and very quickly overcome the tow planes elevator authority
Would this not be trivially solvable with a system that detects the situation (e.g. by measuring the forces acting on the towing plane's attachment point) and detaches the tow? If in the final concept the towed plane would be unmanned and wouldn't contain fuel, even a crash would not be particularly catastrophic.
This product is for towing behind another aircraft, but what about winch towing?
A winched glider implements flight with renewable electricity and it does so efficiently because the power and motor never leave the ground!
A glider can climb up to 5000 feet and travel 50x that before making a landing. Wouldn’t it be glorious to see cargo being autonomously slung from site to site across the world, powered entirely by green electricity?
The we simplify it by putting the winch on rails, and give the glider wheels, then we can chain them together and then we’ve reinvented the railroad, badly.
Nah. You've messing up something 4chan worked out years ago. You need a BLIMPTRAIN! Locomotive on rails towing a train of lighter than air vehicles that can detach under optimal conditions/location to deliver their cargo over the last mile.
Try loading 10 tons into some glider and shooting it up. First the winch would have to be absolutely massive, second its highly reliant on at least a bit good weather and nobody glides around during night. Pilotless doesn't remove danger of it falling onto some roof, so automation would have to be pretty much flawless.
Truck, you can load and send it much further than any glider can ever glide, any time, any day. Also throughput of highways is much bigger than airports, and you can deliver it literally to the target doors.
I've done a few gliding flights. They were all towed to height by a powered aircraft and then released. Winch launch is an alternative to towing, but sounded like a fairly terrifying alternative where you were yoinked into the air by a huge winch. The terror isn't an issue if the glider is pilotless. But IIRC they used something like a 7 litre engine to winch an incredibly light glider. Presumably it would require something really powerful to launch a cargo glider.
I did once fly as a guest with a winch start, and yes it is something. The ascend is pretty steep and the acceleration is powerful. The pilot did not find good lift and we had to land shortly after. My stomach did not like his curving around looking for lift, so I wasn't too unhappy about the short flight.
Is a glider basically joinked into the air by a large and fast winch, and then detached and the glider glides on it's own "power" back to the landing? Or is the winch at the destination, with a cable going _all_ the way across the landscape to where the launch point is, so that it can pull the glider over?
Winch launches are a lot like a kid with a kite. Run fast (wind in the winch) to get speed and up it goes. At its desired altitude, the glider disconnects and goes on its way. https://youtu.be/YePIJKs5me0 gives you an idea.
On a day with a decent breeze, it is possible to "kite" a glider up to very high altitude by letting the wire out again. But this is highly frowned upon because it means there is a very long (and nearly invisible) wire dangling right through the airspace used by other aircraft!
The winch launches the glider and gives it speed from the ground that it can then convert into enough altitude (ie time) for the pilot to find a rising air current (ideally, I guess).
Edit: so yes, your first thought is correct. :) It's somewhat similar to an aircraft carrier launch except that the glider can get a lot more altitude out of it.
I'm the wrong kind of engineer to work it out, but I'd be interested to know what the implications for the strength of the cable and specifications for the winch would be for a heavy cargo glider.
Thinking on, specifying the weak links and managing failed winch launches (which happen fairly regularly) is interesting to consider. Recreational gliders are light enough to be manoeuvred by hand, although old farm tractors are used to move them more than a few dozen feet. How would all that work?
Do you mean laying out 50 mile long cables from place to place with big engines on the ground that pull in a cable at a couple hundred miles per hour after a plane attaches to it? That wouldn't work. Not even if you skipped tow out a cable from your departure point so it could be reused.
And if you had a track for the cable to run in or a carriage holding the winch to drive travel along, then you would just make it rail freight.
No. Winch glider launches (which are not a new thing) use a ground-based winch to give the glider an initial impulse, and the glider uses that to gain altitude and then glide for a much longer distance.
Also, how much does it decrease the fuel economy of the towing plane?
I sure wouldn't want to be on a Boeing 7XX flight with one of these things in tow. Just imagine the possibility for human and machine error, the plane in tow could cause all manner of issues for the leader.
Ever tried riding a bike and towing someone on another bike or a skateboard? It's perilous. Now do it in the air. Gutsy.
It looks like the prototypes land separately because they are converted aircraft. The production glider uses autopilot and is meant to land behind the main aircraft.
Their current implementation (or prototype?) actually uses a powered airplane instead of a glider, which has its engines on for takeoff and then switches them off during the gliding phase (https://www.aerolane.com/aerocart, "How planes fly with AC0 today"). This way it works of course, but I'm not convinced it would be possible to take off with a glider in tow when the lead plane is already near its MTOW (if you'd have to reduce the loading of the lead plane to be able to accomodate the glider, that would defeat the whole purpose of what you're trying to do)?
To be pedantic, an aircraft's MTOW is a function of the structural strength of the airframe and landing gear and doesn't depend on conditions. The Regulated Takeoff Weight is what depends on temperature, air density, headwinds, runway length, etc, and is driven by whether the plane can get airborne before running out of runway (with a lot of margin for contingencies.)
For many planes under good conditions (high density, high headwind) acceleration to takeoff speed isn't the limit, but only airframe strength. Under those conditions, you could tow significant extra weight. The existing fleet of older planes includes many that have had engine upgrades, so they can pull a lot more weight than their MTOW.
Runway length has to include room for a rejected takeoff, for when the engine loses power just before you get to rotation speed. I don't think it'd be fun to try to reject a takeoff with a heavily loaded cargo trailer behind you. The trailer must have its own brakes, but it sounds scary.
Perhaps the glider isn't strictly a glider but has some electric assist that's only used for takeoff and initial climbout? Electric achieves unprecedented power per weight when you only need battery for a minute or two.
If you can leave all the endurance for cruise and main climb to the lead plane, electric becomes almost trivial.
This seems to be the make-or-break aspect of the entire idea and the claim does seem incredibly suspect to me too. OTOH lying about something basic like this doesn't seem like a viable "business" idea. Is there any more documentation/evidence/explanation available for this?
Instead, can we implement autonomous formation flying? Each aircraft can still have its own engines and control, but can make a V shape allowing the following planes to run more efficiently.
This has been attempted (for a military aircraft IIRC), and proved too difficult to be practical. It may now be possible, but it is more challenging that it appears from just watching our feathered friends.
The physical linkage aspect of this just seems so dangerous. As other commenters have pointed out glider tow accidents are a real thing. Luckily gliders are light and typically operating at low speed. Adding a 10,000 lb aircraft to this situation seems wild.
Airbus concepts like fello'fly[1] and GEESE seem significantly safer. I could see using something like a lead aircraft with several drones following in formation and breaking off for takeoff and landing operations. Reliable Robotics is already working on autonomous small cargo aircraft for these types of regional cargo operations.
The military gliders made sense because they were landing in hostile territory, usually nowhere near a runway for a return trip. Those gliders were pretty much a one-way, one-time-use vehicle. I guess the Waco glider could be used to argue that towing is technically feasible, but it was intended for a totally different use case. I don't see how it can be argued that it's more economical to run, especially considering the safety issues others have pointed out.
I'm no aerospace engineer but it seems like it would be more efficient to fly one single bigger plane than to tow a second one behind it. I suppose this might appeal to certain groups where they already own a plane, and want to increase capacity without buying a whole new plane. But the idea that it's 65% more efficient just seems pretty sketch. I could totally imagine some drug cartels using these though...
If you've got a bigger plane, you also need a bigger runway. This thing should increase the number of usable airfields. That could be interesting for avoiding more expensive routes.
"When towing Aerocarts, planes instantly double or triple their payload capacity. This is because their capacity is limited by the takeoff / landing weight – not what they can safely pull through the air."
But later, on "How it works" section it is apparent that the main plane still has to tow the cart behind it when taking off. What's the trick that makes this work? Extra set of wings?
Yes, the wings of the glider provide lift that otherwise would not be present. The engines still need to produce more thrust to pull the glider but that's expected, the extra cargo doesn't come free.
That... kind of makes sense. But (the way I* see it) modern large aircraft aren't very overpowered (otherwise they would be less efficient), so their engine power is just a little bit above what's needed to get them into the air with a "usual" runway size in ~ the worst possible conditions ("hot & high"). Which means that they would need ~ double the runway length to take off with a glider in tow? So this works with the small aircraft they're currently testing with (they just have to use a longer runway), but if they want to extend it to larger cargo jets, they would risk exceeding the limitations of existing airport runways?
________
* - someone who has an interest in aviation, but no professional background or training therein
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This is my biggest concern with this concept as well. Towing things is challenging because the tow plane's center of gravity can change drastically depending on the forces on the glider it is towing -- if the glider deploys its spoilers / crabs in a crosswind / gets in your wake turbulence you're not going to be able to predict how it changes your CG (and your control authority) without training or experience. Also, with gliders, the tow plane is traveling at around 60MPH to 90MPH, with a decision window of 2-3 seconds. Commercial planes travel at ~500 MPH... The concept seems like a hard sell to the pilot unions. I bet they've thought about this though.
Would this not be trivially solvable with a system that detects the situation (e.g. by measuring the forces acting on the towing plane's attachment point) and detaches the tow? If in the final concept the towed plane would be unmanned and wouldn't contain fuel, even a crash would not be particularly catastrophic.
https://en.wikipedia.org/wiki/Messerschmitt_Me_323_Gigant#Me...
https://ww2talk.com/index.php?threads/glider-towing.22518/
Deleted Comment
A winched glider implements flight with renewable electricity and it does so efficiently because the power and motor never leave the ground!
A glider can climb up to 5000 feet and travel 50x that before making a landing. Wouldn’t it be glorious to see cargo being autonomously slung from site to site across the world, powered entirely by green electricity?
https://youtu.be/A-RfHC91Ewc?si=uMjPf00zqbJHfSwn
We are so smart that we can take good things and modify them in stupid ways to make bad things. This is, in fact, very smart of us.
Winch launching is already a thing https://youtu.be/U3ztaJ0yfxE?si=1AjAS8F8-pCaUFZI
I can see a big winch glider being worthwhile in some very limited circumstances.
Truck, you can load and send it much further than any glider can ever glide, any time, any day. Also throughput of highways is much bigger than airports, and you can deliver it literally to the target doors.
Not a very practical fantasy it seems.
Is a glider basically joinked into the air by a large and fast winch, and then detached and the glider glides on it's own "power" back to the landing? Or is the winch at the destination, with a cable going _all_ the way across the landscape to where the launch point is, so that it can pull the glider over?
I'm a tad confused.
On a day with a decent breeze, it is possible to "kite" a glider up to very high altitude by letting the wire out again. But this is highly frowned upon because it means there is a very long (and nearly invisible) wire dangling right through the airspace used by other aircraft!
Edit: so yes, your first thought is correct. :) It's somewhat similar to an aircraft carrier launch except that the glider can get a lot more altitude out of it.
Thinking on, specifying the weak links and managing failed winch launches (which happen fairly regularly) is interesting to consider. Recreational gliders are light enough to be manoeuvred by hand, although old farm tractors are used to move them more than a few dozen feet. How would all that work?
And if you had a track for the cable to run in or a carriage holding the winch to drive travel along, then you would just make it rail freight.
https://glidingschool.com/briefing-winch-launch/
(Now that I mention it, why don’t carriers combine both catapult and ski jump?)
How are they planning to handle aborted takeoffs of towing plane, for example?
How does it integrate with ATC? During towing? During landing of glider?
This video claims that trailer is landing separately and autonomously. Obscure of details. https://www.aerolane.com/news/florida-2025-q1-tests
I sure wouldn't want to be on a Boeing 7XX flight with one of these things in tow. Just imagine the possibility for human and machine error, the plane in tow could cause all manner of issues for the leader.
Ever tried riding a bike and towing someone on another bike or a skateboard? It's perilous. Now do it in the air. Gutsy.
Probably a lot, but I'd assume it is by less than the fuel that 1-2x more planes would use, otherwise there wouldn't be a point to doing this.
This means the consist is capable of taking off on the same runways and with similar climb profiles as the primary tow plane is alone."
This is just denying basic physics. Ask any glider pilot how the climb out on aerotow varies based on the weight of the glider being towed.
For many planes under good conditions (high density, high headwind) acceleration to takeoff speed isn't the limit, but only airframe strength. Under those conditions, you could tow significant extra weight. The existing fleet of older planes includes many that have had engine upgrades, so they can pull a lot more weight than their MTOW.
Runway length has to include room for a rejected takeoff, for when the engine loses power just before you get to rotation speed. I don't think it'd be fun to try to reject a takeoff with a heavily loaded cargo trailer behind you. The trailer must have its own brakes, but it sounds scary.
If you can leave all the endurance for cruise and main climb to the lead plane, electric becomes almost trivial.
Deleted Comment
Airbus concepts like fello'fly[1] and GEESE seem significantly safer. I could see using something like a lead aircraft with several drones following in formation and breaking off for takeoff and landing operations. Reliable Robotics is already working on autonomous small cargo aircraft for these types of regional cargo operations.
[1] https://www.airbus.com/en/innovation/future-aircraft-operati...
I'm no aerospace engineer but it seems like it would be more efficient to fly one single bigger plane than to tow a second one behind it. I suppose this might appeal to certain groups where they already own a plane, and want to increase capacity without buying a whole new plane. But the idea that it's 65% more efficient just seems pretty sketch. I could totally imagine some drug cartels using these though...
"When towing Aerocarts, planes instantly double or triple their payload capacity. This is because their capacity is limited by the takeoff / landing weight – not what they can safely pull through the air."
But later, on "How it works" section it is apparent that the main plane still has to tow the cart behind it when taking off. What's the trick that makes this work? Extra set of wings?
________
* - someone who has an interest in aviation, but no professional background or training therein