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#11
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On Electric Aircraft
On Tuesday, February 11, 2020 at 5:15:04 AM UTC-8, Tim Newport-Peace wrote:
Not Quite True. Since a charged battery contains a greater total amount of energy than a dead battery, the earth's gravity will pull more strongly on it. But you will have trouble measuring the difference ;¬)) But seriously, no. Energy in and of itself has no mass. A an old-time watch or windup toy has the same mass regardless of whether it is wound or unwound. |
#12
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On Electric Aircraft
On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie wrote:
..The one thing we both missed, though is that a good brushless motor plus its controller will be a lighter and smaller than the equivalent ICE piston engine driving a propeller... Not only that, but it delivers smoother power with less vibration, delivers it the moment it is started, requires less service infrastructure (starting, lubrication, cooling, exhaust, etc), and can easily be positioned for stowage. It runs cleaner and cooler and more predictably under a wider range of conditions, and is more easily monitored for performance and troubleshooting. --Bob K. |
#13
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On Electric Aircraft
On Tue, 11 Feb 2020 10:09:18 -0800, Bob Kuykendall wrote:
On Tuesday, February 11, 2020 at 5:15:04 AM UTC-8, Tim Newport-Peace wrote: Not Quite True. Since a charged battery contains a greater total amount of energy than a dead battery, the earth's gravity will pull more strongly on it. But you will have trouble measuring the difference ;¬)) But seriously, no. Energy in and of itself has no mass. A an old-time watch or windup toy has the same mass regardless of whether it is wound or unwound. ....but an electron does have mass, just not very much: 9.1093837015 × 10^-31 kg Not that it matters, because as many electrons flow into a discharging battery as flow out. -- Martin | martin at Gregorie | gregorie dot org |
#14
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On Electric Aircraft
On Tue, 11 Feb 2020 10:16:45 -0800, Bob Kuykendall wrote:
On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie wrote: ..The one thing we both missed, though is that a good brushless motor plus its controller will be a lighter and smaller than the equivalent ICE piston engine driving a propeller... Not only that, but it delivers smoother power with less vibration, delivers it the moment it is started, requires less service infrastructure (starting, lubrication, cooling, exhaust, etc), and can easily be positioned for stowage. It runs cleaner and cooler and more predictably under a wider range of conditions, and is more easily monitored for performance and troubleshooting. Another thing, but this probably doesn't affect us much: a brushless motor, which all these units are, has its rpm set primarily by the rate at which the controller switches power round its (static) field coils and, when driving a propeller, isn't much affected by the load its working against. Its one reason electric brushless motors are popular with the RC and CL aerobatic crowd - the nearly constant RPM causes airspeed on uplines and downlines to be more constant than it ever was with IC engines. -- Martin | martin at Gregorie | gregorie dot org |
#15
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On Electric Aircraft
And who outside of the media did not understand that?
On 2/10/2020 3:28 PM, Eric Greenwell wrote: kinsell wrote on 2/10/2020 7:59 AM: On 2/10/20 8:43 AM, Dan Marotta wrote: A couple of very good perspectives HERE https://www.avweb.com/features/reader-mail/top-letters-and-comments-february-7-2020/?MailingID=280&utm_source=ActiveCampaign&utm_mediu m=email&utm_content=Bryant+Crash+Prelim%2C+Drone+C ertification+NPRM&utm_campaign=Bryant+Crash+Prelim %2C+Drone+Certification+NPRM-Monday+February+10%2C+2020. Let the flames begin... -- Dan, 5J Yep.Â* Came across an article from COPA (Canadian Owners and Pilot's Association) filling in some the the details of the Harbour Air plane. It was so stuffed full of batteries there was hardly any useful load left.Â* Which puts it more in the category of publicity stunt than a serious attempt to develop an electric plane.Â* And of course calling it the first all-electric commercial aircraft is disingenuous in the extreme. https://copanational.org/en/2019/12/...zQBJD3aCPb93FA The article made clear it's _test_ plane, not prototype for the commercial version. That version will use a different chemistry Li battery that is significantly lighter. "The flight was not in a commercial aircraft in the sense that it was certified to carry passengers – it is a prototype used in the certification process. As such, the flight was made for ‘proof of concept’ purposes only." -- Dan, 5J |
#16
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On Electric Aircraft
What a wonderful way to spend a snowy morning, discussing the weight of
a full versus an empty battery! What if we talked in terms of mass instead of weight? :-D Seriously, I got a lot of entertainment after the thread went off topic as is so normal with RASicrucians.Â* I especially liked the comparison that Bob made of a wound versus unwound watch or toy. I've been banging my head against the wall trying to see that in the context of the Laws of Conservation of Matter and Energy. More coffee is in order... On 2/11/2020 11:34 AM, Martin Gregorie wrote: On Tue, 11 Feb 2020 10:16:45 -0800, Bob Kuykendall wrote: On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie wrote: ..The one thing we both missed, though is that a good brushless motor plus its controller will be a lighter and smaller than the equivalent ICE piston engine driving a propeller... Not only that, but it delivers smoother power with less vibration, delivers it the moment it is started, requires less service infrastructure (starting, lubrication, cooling, exhaust, etc), and can easily be positioned for stowage. It runs cleaner and cooler and more predictably under a wider range of conditions, and is more easily monitored for performance and troubleshooting. Another thing, but this probably doesn't affect us much: a brushless motor, which all these units are, has its rpm set primarily by the rate at which the controller switches power round its (static) field coils and, when driving a propeller, isn't much affected by the load its working against. Its one reason electric brushless motors are popular with the RC and CL aerobatic crowd - the nearly constant RPM causes airspeed on uplines and downlines to be more constant than it ever was with IC engines. -- Dan, 5J |
#17
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On Electric Aircraft
You mean that a glider hs a higher mass after releasing from tow because you added potential energy??
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#18
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On Electric Aircraft
Ummm, the COPA article is not the message that Harbour Air and Magnix have been putting out. This is representative of the story they tell, indicating the prototype is ready for certification: https://www.flightglobal.com/airline...135711.article And yes, there's lots of people not associated with aviation that are being mislead by this. -Dave On 2/11/20 11:56 AM, Dan Marotta wrote: And who outside of the media did not understand that? On 2/10/2020 3:28 PM, Eric Greenwell wrote: kinsell wrote on 2/10/2020 7:59 AM: On 2/10/20 8:43 AM, Dan Marotta wrote: A couple of very good perspectives HERE https://www.avweb.com/features/reader-mail/top-letters-and-comments-february-7-2020/?MailingID=280&utm_source=ActiveCampaign&utm_mediu m=email&utm_content=Bryant+Crash+Prelim%2C+Drone+C ertification+NPRM&utm_campaign=Bryant+Crash+Prelim %2C+Drone+Certification+NPRM-Monday+February+10%2C+2020. Let the flames begin... -- Dan, 5J Yep.Â* Came across an article from COPA (Canadian Owners and Pilot's Association) filling in some the the details of the Harbour Air plane. It was so stuffed full of batteries there was hardly any useful load left.Â* Which puts it more in the category of publicity stunt than a serious attempt to develop an electric plane.Â* And of course calling it the first all-electric commercial aircraft is disingenuous in the extreme. https://copanational.org/en/2019/12/...zQBJD3aCPb93FA The article made clear it's _test_ plane, not prototype for the commercial version. That version will use a different chemistry Li battery that is significantly lighter. "The flight was not in a commercial aircraft in the sense that it was certified to carry passengers – it is a prototype used in the certification process. As such, the flight was made for ‘proof of concept’ purposes only." |
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