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Aerocart cargo gliders

aerolane.com

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Re: Aerocart cargo gliders

#71

Post by kakacik »

gorgoiler wrote: post #35

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…

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.

Not a very practical fantasy it seems.

Re: Aerocart cargo gliders

#72

Post by roeles »

hermitcrab wrote: post #58
rkomorn wrote: post #47

Earlier quoted context omitted.

"Weight doesn't affect glide ratio" is one of these things I learned why taking flying lessons that still feels counterintuitive every time I read it. (Don't worry, reader, I never intended to get a pilot's license.)

So, 2 gliders with identical geometry, one standard and one made of lead will have the same glide angle? That sounds unlikely.

The same angle, but at different speeds. The speed is multiplied by the square root of the weight ratio (new/reference).

The minimum speed, at which the critical aoa is reached, increases. And therefore the take off and landing speeds.

Re: Aerocart cargo gliders

#73

Post by beAbU »

gorgoiler wrote: post #35

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…

Can you please ELI5 winched gliding to me?

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.

Re: Aerocart cargo gliders

#74

Post by roeles »

rkomorn wrote: post #69
hermitcrab wrote: post #67

Earlier quoted context omitted.

Thanks for the links. Weight may cancel out of the equations, but (being a bit pedantic) I suspect 'glide angle in independent of weight' only holds up to a point. Taking things to extremes, if the glider is heavy enough that you are going to have to go supersonic then I suspect a lot of the assumptions become invalid. NB/ spherical cows are unable to glide in a vacuum.

I assume it is a relevant enough concept to flying an aircraft (which also happens to be the context of TFA) that you learn about it while flying. I guess another thing worth noting is that "glide ratio" isn't the same as "gliding" in the "flying a glider" context. The space shuttle is probably the most famous glider, and was described as "a flying brick" and getting it to the ground at the right spot was very much a…

Weight affects speed with minimum sink. That affects the diameter of the circle you fly. Since thermals have more lift towards the center (assuming perfectly circular thermals), you are not able to circle in the strongest lift. So you climb more slowly.

You can glide faster with the same L/D, so that might be worth it if you try to optimize for speed.

Re: Aerocart cargo gliders

#75

Post by [deleted] »

usrusr wrote: post #40
plantain wrote: post #26

"Despite the higher mass, takeoff & climb performance of the consist is similar to that of the lead plane flying independently. 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.

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.

[deleted]

Re: Aerocart cargo gliders

#76

Post by gorgoiler »

beAbU wrote: post #73
gorgoiler wrote: post #35

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…

Can you please ELI5 winched gliding to me? 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.

You nailed it: the winch pulls the glider rapidly up to altitude, lets go, and the glider floats back down to earth.

Re: Aerocart cargo gliders

#77

Post by tlb »

rob74 wrote: post #53
plantain wrote: post #26

"Despite the higher mass, takeoff & climb performance of the consist is similar to that of the lead plane flying independently. 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.

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…

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.

Re: Aerocart cargo gliders

#78

Post by plasticchris »

eptcyka wrote: post #44
gorgoiler wrote: post #35

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…

Traditionalcgliders are incredibly light, I doubt anything careying sufficient cargo will be able to do a 50:1 distance to altitude ratio.

Traditional gliders also carry ballast for cross country flights, which increases their speed without negatively impacting their glide ratio.

Re: Aerocart cargo gliders

#79

Post by bronco21016 »

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.

[1] https://www.airbus.com/en/innovation/future-aircraft-operati...

Re: Aerocart cargo gliders

#80

Post by mhb »

Ruarl wrote: post #50
gorgoiler wrote: post #35

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…

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 tractor…

Maybe this problem is adjacent to catapult launchers on aircraft carriers.
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