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#71
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$1 billion BMS Ooops...
Kenn Sebesta wrote on 3/6/2021 10:31 AM:
I predict that people just want to launch. If we can use 8-10kg of 20C LiPos to get to 1k', with 5 minutes of cruise left over, and a freshly charged pack waiting on the ground, then it's basically a winch launch. And as those of us who have flown in the EU know, winch launches are great ways to get flying. I know people want much more than a launch! Note that sustainers are sold by all the major manufacturers; actually, pretty much all the manufacturers. A company (LZ Design/FES) arose to service that market electrically. A corollary to your density remarks is doubling the battery capacity of that "launch only" glider won't add significant weight or cost, and would enable a couple of saves or a self retrieve. A launch-only glider with easily swapped batteries might make sense as a busy club glider where pilots are flying for an hour near the airport, but no one else will buy one. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 |
#72
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$1 billion BMS Ooops...
On Saturday, March 6, 2021 at 2:03:25 PM UTC-5, Eric Greenwell wrote:
Kenn Sebesta wrote on 3/6/2021 10:31 AM: I predict that people just want to launch. If we can use 8-10kg of 20C LiPos to get to 1k', with 5 minutes of cruise left over, and a freshly charged pack waiting on the ground, then it's basically a winch launch. And as those of us who have flown in the EU know, winch launches are great ways to get flying. I know people want much more than a launch! Note that sustainers are sold by all the major manufacturers; actually, pretty much all the manufacturers. You might be right! I think we're looking at this same coin from two different sides. I'm at the stage of my gliding career where just getting up and staying up is the goal, whereas you are quite a lot more accomplished and value the ability to get home after a long flight. It's tough for me to guess which direction the larger market needs, we'll see what it ultimately decides. As you point out, it's very easy to adjust the amount of available battery energy. A corollary to your density remarks is doubling the battery capacity of that "launch only" glider won't add significant weight or cost, and would enable a couple of saves or a self retrieve. For sure! Although keep in mind that the battery is the single highest $ component of the propulsion system. Moreover, batteries have a fixed lifespan with or without use, so some people might prefer a lower TCO and a lighter plane. I think the beauty of electric is the ability to tailor this to specific needs. We can even imagine the same plane with a lightweight pattern launch battery, and a heftier XC battery. The genius of all this is that as battery tech improves the existing plane just gets better and better. When you're looking at your replacement pack 5-10 years down the road you'll automatically benefit from all the improvements and your new pack will either be cheaper, or it'll fly longer, or it'll be lighter. Maybe all three. Certainly never saw 100LL get cheaper, better, and lighter! |
#73
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$1 billion BMS Ooops...
On Fri, 05 Mar 2021 20:56:50 -0800, jfitch wrote:
Comparisons of commercial air transport with self launched gliders are specious, very different energy use profile. Same with cars vs. self launched gliders. In either case though, the energy density difference between 100LL and state-of-the-art batteries is hard to ignore - at least 30:1 at this moment, and still 10:1 even considering relative efficiencies. I've no doubt electrics will eventually take over, the question is only if you buy one now, how early are you in the development cycle? Once the cycle is mature, there should be a market for a drop in electric replacement for aging ICE powerplants on popular gliders. Has anybody else on here read David Brin's 'Existence'? It suggests one way to make mass electric-powered air transport work: Put the pax and cargo in nice accommodation on a large airship and tow it cross country behind an electric locomotive running on repurposed AmTrak tracks. What he describes is an interesting case of "look ma! No batteries!". -- Martin | martin at Gregorie | gregorie dot org |
#74
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$1 billion BMS Ooops...
On Sat, 06 Mar 2021 12:13:38 -0800, Kenn Sebesta wrote:
For sure! Although keep in mind that the battery is the single highest $ component of the propulsion system. Moreover, batteries have a fixed lifespan with or without use, so some people might prefer a lower TCO and a lighter plane. I think the beauty of electric is the ability to tailor this to specific needs. We can even imagine the same plane with a lightweight pattern launch battery, and a heftier XC battery. Speaking as a pilot whose launch method of choice is the winch, I think the way to go could well be an electric sustainer launched with an electric winch: potentially 100% green and no need for big, heavy batteries. However, launching an electric sustainer with a Polish gravity launch would be super-cool. The genius of all this is that as battery tech improves the existing plane just gets better and better. All the practical battery chemistries have been tried by now and their specific energy capacities are well-known, so I suspect that future improvement will be along the lines of incremental weight reduction, better durability and, possibly, price reduction as recycling techniques are improved. OTOH if battery recycling doesn't become very close to zero loss for the active material in a battery, prices will rise as mines get worked out, and IIRC the reserves of these sources are fairly well- known. Questions we need to know the answers for very soon a - How widespread is battery material recycling at present? - Can you yet buy a battery containing recycled Lithium? - If not, why not? -- Martin | martin at Gregorie | gregorie dot org |
#75
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$1 billion BMS Ooops...
It suggests one way to make mass electric-powered air transport work: Put
the pax and cargo in nice accommodation on a large airship and tow it cross country behind an electric locomotive running on repurposed AmTrak tracks. And just what happens when the train goes under a bridge? Another unicorn inspired idea. Keep 'em coming. I need the laughs. |
#76
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$1 billion BMS Ooops...
On Sun, 07 Mar 2021 04:44:36 -0800, Mark Mocho wrote:
It suggests one way to make mass electric-powered air transport work: Put the pax and cargo in nice accommodation on a large airship and tow it cross country behind an electric locomotive running on repurposed AmTrak tracks. And just what happens when the train goes under a bridge? Another unicorn inspired idea. Keep 'em coming. I need the laughs. The author is a bit more than a unicorn, methinks. He's well-regarded in technical circles. Anyhow, if such a system was set up it could obviously only work on lines that have no tunnels and that don't run in deep valleys (so not on the Glendale-Denver line obviously), and that have been 'adjusted' so that the line is always at the top of the crossing stack. It would also be faster than the old Goon Show concept of horse-drawn zeppelins. -- Martin | martin at Gregorie | gregorie dot org |
#77
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$1 billion BMS Ooops...
It would also be faster than the old Goon Show concept of horse-drawn
zeppelins. Yes, it would effectively take the speed and omnidirectional attribute of air travel and relegate it to the pathways and speed range of a railroad. And only if you can find a rail line that has no tunnels, bridges or power transmission lines crossing it. And you now eliminate travel to destinations that have no existing rail lines. It's like taking a wireless voice communication system and turning it into a teletype. Oh, wait- That's the iPhone. Being well-regarded in technical circles does not necessarily mean you won't come up with a bad idea once in a while. Next up: How to make an ASG-29 perform like a paraglider. |
#78
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$1 billion BMS Ooops...
On Sun, 07 Mar 2021 06:38:22 -0800, Mark Mocho wrote:
Being well-regarded in technical circles does not necessarily mean you won't come up with a bad idea once in a while. Indeed, IME his SF varies in quality and ingenuity: some (Earth, Sundiver plus the next two followups, Kil'n People, The Practise Effect) were excellent, the others including Existence, not so much. Next up: How to make an ASG-29 perform like a paraglider. Good luck with that: I'd settle for a new build carbon Libelle. -- Martin | martin at Gregorie | gregorie dot org |
#79
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$1 billion BMS Ooops...
Mark Mocho wrote on 3/7/2021 6:38 AM:
Next up: How to make an ASG-29 perform like a paraglider. I have dreams like that. It makes the off-field landings so much easier, way better than the already very good high-deflection landing flaps. I envy birds for their STOL skills, and wish our gliders could emulate them. The closest we've come might be the 90 degree flaps like Dick Schreder used, or the BRS parachutes. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 |
#80
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$1 billion BMS Ooops...
On 3/7/2021 8:31 AM, Martin Gregorie wrote:
On Sun, 07 Mar 2021 04:44:36 -0800, Mark Mocho wrote: It suggests one way to make mass electric-powered air transport work: Put the pax and cargo in nice accommodation on a large airship and tow it cross country behind an electric locomotive running on repurposed AmTrak tracks. And just what happens when the train goes under a bridge? Another unicorn inspired idea. Keep 'em coming. I need the laughs. The author is a bit more than a unicorn, methinks. He's well-regarded in technical circles. Anyhow, if such a system was set up it could obviously only work on lines that have no tunnels and that don't run in deep valleys (so not on the Glendale-Denver line obviously), and that have been 'adjusted' so that the line is always at the top of the crossing stack. It would also be faster than the old Goon Show concept of horse-drawn zeppelins. Or you can use the newfangled idea of making that airship very narrow and fly it very low to the ground so it can go under the bridges and through tunnels. Oh wait... While the rest of the world has double-tracked and electrified their long-range railroads (e.g., the trans-Siberia), here in the US we sit on our heels while a few loonies play with "pods" and other nonsense. But I'm getting further off topic. Gliders are nice. They don't need no steenkin' engines. |
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