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Aerocart cargo gliders

aerolane.com

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Re: Aerocart cargo gliders

#91

Post by potato3732842 »

bombcar wrote: post #70
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…

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.

Building a railroad over water or through a jurisdiction full of jerks is expensive.

I can see a big winch glider being worthwhile in some very limited circumstances.

Re: Aerocart cargo gliders

#92

Post by palijer »

There's no way to make these safe - it's almost comical and this could be an April 1st joke.

Case 1) how are you handling potential rapid TCAS climbs/decent? You're making the targets a lot larger and less responsive. If TCAS commands a decent and slow down, you will be overtaken by the tow.

Case 2) landings thay require rapid braking, such as short runways for emergencies or engine fires (rapid brakes used so emergency vehicles don't have to chase 2km to get to you)

Case 3) aborted take offs. Brakes will need to be more performant and reactive than the ones we have on the main aircraft

Case 4) taxiing across active runways now has reduced margins.

Case 5) go-around performance is diminished. Already sometimes tight margins on that, what happens if you need to do a go around but the landing gear on the glider collapsed and is now a ground anchor?

Re: Aerocart cargo gliders

#93

Post by korse »

bombcar wrote: post #70
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…

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.

Re: Aerocart cargo gliders

#94

Post by decafninja »

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…

How about a carrier style electromagnetic catapult to launch the glider? Except make it ski jump style so that the glider gains initial altitude.

(Now that I mention it, why don’t carriers combine both catapult and ski jump?)

Re: Aerocart cargo gliders

#95

Post by stinkbeetle »

wildzzz wrote: post #89
stinkbeetle wrote: post #49

Earlier quoted context omitted.

Well then it's even simpler, carrying any worthwhile amount of cargo in a winch launched glider is not going to work.

It would work fine for sending small payloads short distances but unless you're in a hurry, it would be much easier to just send more mass by truck or train. One big benefit is having a truck or train being able to return to its origin without requiring another launch facility and also being able to travel in nearly all weather. There may be some use cases where drone gliders could airdrop payloads and return to thei…

It wouldn't work very fine at all. Gliding at low speed a minuscule payload 50-100 miles that you have to transfer to the airport at the departure point then from the airport at the destination will almost certainly take longer and be much more expensive in terms of infrastructure and worker cost than just driving it point to point in a delivery vehicle. It's also highly weather dependent, much more so than powered aircraft.

If you're really in a hurry you need a helicopter. Then pay your indulgences to some politician's shady "carbon credit" corporation if you feel guilty about your climate sin, or use a carbon-neutral manufactured kerosene for it, and then you're even greener and still cheaper than the unpowered spruce goose idea.

Re: Aerocart cargo gliders

#96

Post by rkomorn »

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.

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.

Re: Aerocart cargo gliders

#97

Post by ahartmetz »

rkomorn wrote: post #47
roeles wrote: post #45

Earlier quoted context omitted.

Glide ratio and weight are not related. Weight shifts the glide Polar to higher speeds and theoretically improves it slightly due to Reynolds effects.

"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.)

I don't think it's completely true. Higher weight increases the speed at which the glide ratio is optimal, and drag (parasitic drag in particular, unrelated to generating lift) increases with the square of speed. Basically, flying faster wastes more energy. That effect is going to dominate at some point, probably about 120 km/h or so with a typical glider. At 200 km/h, the glide ratio is garbage (but it's fun). I have flown gliders.

I'm not sure if simple descriptions of the phenomenon that glide ratio is independent of weight are missing an asterisk or if I'm just wrong...

A decent glider has a ratio of 1:40, an A320 1:17. Is the A320 a "bad plane" or is it optimized for higher speed with the corresponding worse glide ratio? (It also has engines that produce a lot of drag when gliding)

Re: Aerocart cargo gliders

#98

Post by rkomorn »

ahartmetz wrote: post #97
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.)

I don't think it's completely true. Higher weight increases the speed at which the glide ratio is optimal, and drag (parasitic drag in particular, unrelated to generating lift) increases with the square of speed. Basically, flying faster wastes more energy. That effect is going to dominate at some point, probably about 120 km/h or so with a typical glider. At 200 km/h, the glide ratio is garbage (but it's fun). I hav…

I don't know. On one hand there's your take.

On another hand, there are CFIs, the FAA, books, etc.

I've only found one search result that agrees with you, so far, and at least a dozen that disagree, but the one that agrees with you has no math in it, and the ones that disagree mostly seem to depend on the same source info, so that doesn't feel conclusive in either direction.

The Wikipedia page on lift-to-drag ratio also believes weight does not matter to the ratio.

As a side note, your 200km/h example also sounds like it's just not the correct angle of attack or airspeed for the aircraft, so I'm not sure if that example applies?

Re: Aerocart cargo gliders

#99

Post by rkomorn »

ahartmetz wrote: post #97
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.)

I don't think it's completely true. Higher weight increases the speed at which the glide ratio is optimal, and drag (parasitic drag in particular, unrelated to generating lift) increases with the square of speed. Basically, flying faster wastes more energy. That effect is going to dominate at some point, probably about 120 km/h or so with a typical glider. At 200 km/h, the glide ratio is garbage (but it's fun). I hav…

As a separate reply, I'll add that I think finding where/if this breaks is pretty academic.

Eg: you wouldn't build a glider out of heavy material that gives you huge speeds but also huge sink rates.

So I think the entire glide ratio conversation mostly fits in the "your plane is fully loaded" vs "your plane is empty" scenario, and the point is that your best glide ratio will be constant, but you'll be gliding at higher speeds if you have more weight.

Re: Aerocart cargo gliders

#100

Post by drpixie »

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.

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!

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