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#31
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Future of aviation, or flash in the pan??
On Tuesday, January 28, 2020 at 1:48:48 AM UTC-5, jfitch wrote:
On Monday, January 27, 2020 at 7:04:36 PM UTC-8, Dave Nadler wrote: On Sunday, January 26, 2020 at 7:14:12 PM UTC-5, jfitch wrote: ...an electric retrofit for the AS self launchers. The engineering and installation should be relatively simple. Um, not on this planet. Perhaps you did not catch the "relatively"? Engine bay is already there, the doors are there, it is engineered and built for the weight, the extraction mechanism is already there, even the prop and boom. So yes, "relatively simple" compared to retrofitting say an ASW27, which is being done, and has none of those things. I am not a stranger to complexity, or aircraft design. "How hard could it be" That depends. Certainly if you already have an engine bay, and lift mechanism, you have a great start. No engineering the hole in the fuselage, etc. If you have a proven drive system, much of the next part is more easily accomplished. 2 meaningful issues with converting the later Schleicher ships: 1) Where do the batteries go? Engine bay has some room but CG possibilities become limited. Wing installation would most certainly involve major stuff in any of the hard tank wings. Support and service access are non trivial. This is the major task on the '34. The rest is mostly transplanting proven motor and drive into the '34 from the 32E. 2) Engine bay size matters because it limits available prop diameter and this is a real issue in getting performance out of the drive. I have some practical experience with this as I am now starting test flying of an ASW-24E that has been converted to electric. How hard could it be? The largest barrier is a lack of proven motor/ controller systems to incorporate into a project. FWIW UH |
#33
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Future of aviation, or flash in the pan??
On Tuesday, January 28, 2020 at 6:59:56 AM UTC-8, wrote:
On Tuesday, January 28, 2020 at 1:48:48 AM UTC-5, jfitch wrote: On Monday, January 27, 2020 at 7:04:36 PM UTC-8, Dave Nadler wrote: On Sunday, January 26, 2020 at 7:14:12 PM UTC-5, jfitch wrote: ...an electric retrofit for the AS self launchers. The engineering and installation should be relatively simple. Um, not on this planet. Perhaps you did not catch the "relatively"? Engine bay is already there, the doors are there, it is engineered and built for the weight, the extraction mechanism is already there, even the prop and boom. So yes, "relatively simple" compared to retrofitting say an ASW27, which is being done, and has none of those things. I am not a stranger to complexity, or aircraft design. "How hard could it be" That depends. Certainly if you already have an engine bay, and lift mechanism, you have a great start. No engineering the hole in the fuselage, etc. If you have a proven drive system, much of the next part is more easily accomplished. 2 meaningful issues with converting the later Schleicher ships: 1) Where do the batteries go? Engine bay has some room but CG possibilities become limited. Wing installation would most certainly involve major stuff in any of the hard tank wings. Support and service access are non trivial. This is the major task on the '34. The rest is mostly transplanting proven motor and drive into the '34 from the 32E. 2) Engine bay size matters because it limits available prop diameter and this is a real issue in getting performance out of the drive. I have some practical experience with this as I am now starting test flying of an ASW-24E that has been converted to electric. How hard could it be? The largest barrier is a lack of proven motor/ controller systems to incorporate into a project. FWIW UH So how hard was it, for a very skilled and practiced professional? Will you be publishing an article in Soaring, a pre-writeup on RAS? Sounds very interesting. |
#34
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Future of aviation, or flash in the pan??
On Tuesday, January 28, 2020 at 6:59:56 AM UTC-8, wrote:
On Tuesday, January 28, 2020 at 1:48:48 AM UTC-5, jfitch wrote: On Monday, January 27, 2020 at 7:04:36 PM UTC-8, Dave Nadler wrote: On Sunday, January 26, 2020 at 7:14:12 PM UTC-5, jfitch wrote: ...an electric retrofit for the AS self launchers. The engineering and installation should be relatively simple. Um, not on this planet. Perhaps you did not catch the "relatively"? Engine bay is already there, the doors are there, it is engineered and built for the weight, the extraction mechanism is already there, even the prop and boom. So yes, "relatively simple" compared to retrofitting say an ASW27, which is being done, and has none of those things. I am not a stranger to complexity, or aircraft design. "How hard could it be" That depends. Certainly if you already have an engine bay, and lift mechanism, you have a great start. No engineering the hole in the fuselage, etc. If you have a proven drive system, much of the next part is more easily accomplished. 2 meaningful issues with converting the later Schleicher ships: 1) Where do the batteries go? Engine bay has some room but CG possibilities become limited. Wing installation would most certainly involve major stuff in any of the hard tank wings. Support and service access are non trivial. This is the major task on the '34. The rest is mostly transplanting proven motor and drive into the '34 from the 32E. 2) Engine bay size matters because it limits available prop diameter and this is a real issue in getting performance out of the drive. I have some practical experience with this as I am now starting test flying of an ASW-24E that has been converted to electric. How hard could it be? The largest barrier is a lack of proven motor/ controller systems to incorporate into a project. FWIW UH The engine bay is quite large, and would be unoccupied by motor and muffler, and requires about 170 lbs to achieve normal W/B. The space in the wheel well used for the fuel tanks is also available, though the volume in the engine bay alone is probably enough. In my post I suggested that Schleicher do this (instead of the 34), they have already developed the motor/battery/controller for use in other gliders, so that is not a barrier for them. Thus "relatively simple". I'll stand by that characterization. |
#35
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Future of aviation, or flash in the pan??
I wonder if you had a plane with ballast bags, if that would make wing batteries easier.
Not sure if the wing structure expects such concentrated loads? |
#36
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Future of aviation, or flash in the pan??
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#37
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Future of aviation, or flash in the pan??
An interesting question.Â* How does the mass of the batteries compare to
that of water?Â* In my old LS-6a the water was held in bags which ran from the root almost to the tip ahead of the spar.Â* They were drawn in by a light rope and pulley system.Â* I would imagine that the battery cells could be arranged in line, like a machine gun belt and pulled into the wing thus distributing the load.Â* A lot would depend on the weight, I suppose. On 1/28/2020 9:58 AM, wrote: I wonder if you had a plane with ballast bags, if that would make wing batteries easier. Not sure if the wing structure expects such concentrated loads? -- Dan, 5J |
#38
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Future of aviation, or flash in the pan??
El martes, 28 de enero de 2020, 15:02:36 (UTC-3), Dan Marotta escribió:
An interesting question.Â* How does the mass of the batteries compare to that of water?Â* In my old LS-6a the water was held in bags which ran from the root almost to the tip ahead of the spar.Â* They were drawn in by a light rope and pulley system.Â* I would imagine that the battery cells could be arranged in line, like a machine gun belt and pulled into the wing thus distributing the load.Â* A lot would depend on the weight, I suppose. On 1/28/2020 9:58 AM, mail.com wrote: I wonder if you had a plane with ballast bags, if that would make wing batteries easier. Not sure if the wing structure expects such concentrated loads? -- Dan, 5J In my case the battery pack weight is 18kg and 1.5m long. That mass in that distributed area is not that critical. |
#39
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Future of aviation, or flash in the pan??
On 1/25/20 2:54 AM, Martin Gregorie wrote:
On Fri, 24 Jan 2020 20:27:45 -0700, kinsell wrote: On 1/24/20 8:07 PM, wrote: On Friday, January 24, 2020 at 12:21:41 PM UTC-5, kinsell wrote: On 1/24/20 9:58 AM, Steve Leonard wrote: Good to run those tests at night so you can see the fire sooner. Good point. But if the main battery ever lit up (8200 lbs of lithium-cobalt) it ought to make quite a bonfire. Somehow flying that thing makes me think of the guy riding the H-bomb in Doctor Strangelove. I do hope they find safer battery chemistries before long. LiFePO4 is much safer, but the energy density is even poorer and the cost even higher. Good analogy. That was Slim Pickens, wasn't it? Someone at Eviation said the thing is (or was) basically a battery with a picture of an airplane painted on it. I wouldn't have guessed they could get 8200 lbs of lithium battery in there and still have room for px. It's am ambitious project, 600 mile range, but at some point reality starts to rear its ugly head. With a big motor on each wingtip (in the photos they look bigger than the rear motor) I do wonder about its handling if one of the wingtip engines fails/gets hit by a goose, etc., or do they just shut down the other wingtip motor and land wherever possible. https://www.youtube.com/watch?v=LsJ0vYnrMxo A little more detail at about 18:20. They claim a climb rate at sea level of 1200 fpm on just the rear engine. All three engines are the same. Interesting comments at 11:15, using differential thrust in combination with tail surfaces to handle cross winds. They say they'll demonstrate 35 mph crosswind landings. |
#40
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Future of aviation, or flash in the pan??
On 1/25/20 9:07 PM, Emir Sherbi wrote:
When you have so much battery capacity. You have a lot power to spare (discharging or charging). If they use the full capacity in two hours without counting the reserve the rate of discharge is 0,5C. And the chare rate is 1C. That is not much workload for most of the popular cells. But you need a extremely big super charger. What may work for one cell doesn't necessarily work for massive series-parallel arrays of cell. If the cells don't stay well balanced, interesting things can happen when you start pumping a million watts into them. |
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