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#52
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Electrically Powered Ultralight Aircraft
On Tue, 07 Aug 2007 19:14:59 GMT, wrote in
: If you go to http://xtronics.com/reference/energy_density.htm you find the energy densities of a lot of things. Propane (liquid) 13,900 Wh/kg Diesel 13,762 Wh/kg gasoline 12,200 Wh/kg Ethanol 7,850 Wh/kg Methanol 6,400 Wh/kg Secondary Lithium - ion Polymer 130 - 1200 Wh/kg Primary Zinc-Air 300 Wh/kg Lead Acid Battery 25 Wh/kg So batteries have to improve by a factor of 10 to match gasoline. When you compare the efficiency of internal combustion Otto Cycle engines (30% - 40%) against electric motors (80% - 95%), it appears that a factor of five might be a more realistic comparison of their relative merits. Then there is the issue of power plant weight... Electric motors don't lose power in thin air either. With regard to reliability, electric motors have only one moving part compared to scores of moving parts for IC engines, their failure rate should be substantially greater than IC engines. |
#53
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Electrically Powered Ultralight Aircraft
In rec.aviation.piloting Gig 601XL Builder wrDOTgiaconaATsuddenlink.net wrote:
wrote: If you go to http://xtronics.com/reference/energy_density.htm you find the energy densities of a lot of things. Propane (liquid) 13,900 Wh/kg Diesel 13,762 Wh/kg gasoline 12,200 Wh/kg Ethanol 7,850 Wh/kg Methanol 6,400 Wh/kg Secondary Lithium - ion Polymer 130 - 1200 Wh/kg Primary Zinc-Air 300 Wh/kg Lead Acid Battery 25 Wh/kg So batteries have to improve by a factor of 10 to match gasoline. Thanks Jim, that is exactly the kind of data I was looking for. It does kind of show that all this talk of electric airplanes while a nice thought is something that at best is way in the future. Well, to be fair, there is solar cell research that if it becomes practical and cheap enough would work on sail planes with lithium batteries. But there is no technology on the horizon for a practical electric 172. -- Jim Pennino Remove .spam.sux to reply. |
#54
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Electrically Powered Ultralight Aircraft
I e-mailed a copy of the article below to Eric Raymond. Here is his reply: Larry, Thanks for the info on Specrolab's progress. I used to be in contact with them, but gave up because their prices were too high. A much more interesting company is SunPower. They are making cheap, one sun cells that are 22% efficient. I plan to use them on my next plane, a two seater. Eric Raymond A two-place photovoltaic powered aircraft will be interesting. Here's some information on SunPower: http://www.sunpowercorp.com http://www.sunpower.com http://www.sunpowercorp.com/commercial/solar_cells.html The SunPower A-300 solar cell is a 125mm, 20% (minimum) efficiency, high-performance, single crystal silicon solar cell. The A-300 cell offers up to 50% more power per unit area than conventional solar cells. It is particularly unique because the metal contacts needed to collect and conduct electricity are located on the back surface – away from the sunlight. This design eliminates the need for reflective metal contacts to be placed on the front of the solar cell, improving our solar cell performance and creating a uniformly smooth, black appearance. ================================================== ======= On Mon, 06 Aug 2007 16:01:03 GMT, Larry Dighera wrote in : On Mon, 06 Aug 2007 06:33:20 -0700, Airjunkie wrote in .com: Eric Raymond has been at it for a long time. Check it out at www.solar-flight.com http://www.solar-flight.com/sslink.html Thank you for the information. His achievement is remarkable for the time. Imagine what he could do 17 years later with today's ~40% efficient photovoltaic cells and light weight lithium-ion polymer batteries: The Boeing Company http://www.boeing.com/news/releases/index.html Boeing Spectrolab Terrestrial Solar Cell Surpasses 40 Percent Efficiency ST. LOUIS, Dec. 06, 2006 -- Boeing [NYSE: BA] today announced that Spectrolab, Inc., a wholly-owned subsidiary, has achieved a new world record in terrestrial concentrator solar cell efficiency. Using concentrated sunlight, Spectrolab demonstrated the ability of a photovoltaic cell to convert 40.7 percent of the sun's energy into electricity. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) in Golden, Colo., verified the milestone. "This solar cell performance is the highest efficiency level any photovoltaic device has ever achieved," said Dr. David Lillington, president of Spectrolab. "The terrestrial cell we have developed uses the same technology base as our space-based cells. So, once qualified, they can be manufactured in very high volumes with minimal impact to production flow." High efficiency multijunction cells have a significant advantage over conventional silicon cells in concentrator systems because fewer solar cells are required to achieve the same power output. This technology will continue to dramatically reduce the cost of generating electricity from solar energy as well as the cost of materials used in high-power space satellites and terrestrial applications. "These results are particularly encouraging since they were achieved using a new class of metamorphic semiconductor materials, allowing much greater freedom in multijunction cell design for optimal conversion of the solar spectrum," said Dr. Richard R. King, principal investigator of the high efficiency solar cell research and development effort. "The excellent performance of these materials hints at still higher efficiency in future solar cells." Spectrolab is reducing the cost of solar cell production through research investments and is working with several domestic and international solar concentrator manufacturers on clean, renewable solar energy solutions. Currently, Spectrolab's terrestrial concentrator cells are generating power in a 33-kilowatt full-scale concentrator system in the Australian desert. The company recently signed multi-million dollar contracts for its high efficiency concentrator cells and is anticipating several new contracts in the next few months. Development of the high-efficiency concentrator cell technology was funded by the NREL's High Performance Photovoltaics program and Spectrolab. A unit of The Boeing Company, Boeing Integrated Defense Systems http://www.boeing.com/ids/index.html is one of the world's largest space and defense businesses. Headquartered in St. Louis, Boeing Integrated Defense Systems is a $30.8 billion business. It provides network-centric system solutions to its global military, government, and commercial customers. It is a leading provider of intelligence, surveillance and reconnaissance systems; the world's largest military aircraft manufacturer; the world's largest satellite manufacturer; a foremost developer of advanced concepts and technologies; a leading provider of space-based communications; the primary systems integrator for U.S. missile defense; NASA's largest contractor; and a global leader in sustainment solutions and launch services. ### |
#55
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Electrically Powered Ultralight Aircraft
On Tue, 7 Aug 2007 14:51:55 -0500, "Gig 601XL Builder"
wrDOTgiaconaATsuddenlink.net wrote in : all this talk of electric airplanes while a nice thought is something that at best is way in the future. That's only true if you overlook Randall Fishman's electrically powered ultralight (http://www.electraflyer.com) and Mr. Monnett's Sonex proof-of-concept Waiex aircraft (http://www.sonexaircraft.com/press/r...r_072407.html). But, I know, you were referring to electrically powered aircraft with the same utility as today's GA aircraft, right? |
#56
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Electrically Powered Ultralight Aircraft
In rec.aviation.piloting Larry Dighera wrote:
On Tue, 07 Aug 2007 19:14:59 GMT, wrote in : If you go to http://xtronics.com/reference/energy_density.htm you find the energy densities of a lot of things. Propane (liquid) 13,900 Wh/kg Diesel 13,762 Wh/kg gasoline 12,200 Wh/kg Ethanol 7,850 Wh/kg Methanol 6,400 Wh/kg Secondary Lithium - ion Polymer 130 - 1200 Wh/kg Primary Zinc-Air 300 Wh/kg Lead Acid Battery 25 Wh/kg So batteries have to improve by a factor of 10 to match gasoline. When you compare the efficiency of internal combustion Otto Cycle engines (30% - 40%) against electric motors (80% - 95%), it appears that a factor of five might be a more realistic comparison of their relative merits. Then there is the issue of power plant weight... Well, you have to look at total system weight. A 100 HP electric motor is not going to be particularly light and the power cables are going to weigh a whole lot more than fuel lines for example. When you look at the total installed system, assuming you have batteries 5 times better than you have now, I doubt the total weight difference will be all that much. Electric motors don't lose power in thin air either. With regard to reliability, electric motors have only one moving part compared to scores of moving parts for IC engines, their failure rate should be substantially greater than IC engines. AC motors have only one moving part but would require a beefy inverter to generate (and induce more system loss) the AC. DC motors have brushes but motor control is simpler. If the DC motor was designed for easy inspection and replacement of the brushes, then the failure rate should be much lower than a gas engine. -- Jim Pennino Remove .spam.sux to reply. |
#57
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Electrically Powered Ultralight Aircraft
Larry Dighera wrote:
On Tue, 7 Aug 2007 14:51:55 -0500, "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in : all this talk of electric airplanes while a nice thought is something that at best is way in the future. That's only true if you overlook Randall Fishman's electrically powered ultralight (http://www.electraflyer.com) and Mr. Monnett's Sonex proof-of-concept Waiex aircraft (http://www.sonexaircraft.com/press/r...r_072407.html). But, I know, you were referring to electrically powered aircraft with the same utility as today's GA aircraft, right? Right. When the electric Sonex can do the same thing the VW powered Sonex can do then it will become something more than an interesting idea. |
#58
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Electrically Powered Ultralight Aircraft
Larry Dighera wrote:
On Tue, 07 Aug 2007 19:14:59 GMT, wrote in : If you go to http://xtronics.com/reference/energy_density.htm you find the energy densities of a lot of things. Propane (liquid) 13,900 Wh/kg Diesel 13,762 Wh/kg gasoline 12,200 Wh/kg Ethanol 7,850 Wh/kg Methanol 6,400 Wh/kg Secondary Lithium - ion Polymer 130 - 1200 Wh/kg Primary Zinc-Air 300 Wh/kg Lead Acid Battery 25 Wh/kg So batteries have to improve by a factor of 10 to match gasoline. When you compare the efficiency of internal combustion Otto Cycle engines (30% - 40%) against electric motors (80% - 95%), it appears that a factor of five might be a more realistic comparison of their relative merits. Then there is the issue of power plant weight... Electric motors don't lose power in thin air either. With regard to reliability, electric motors have only one moving part compared to scores of moving parts for IC engines, their failure rate should be substantially greater than IC engines. Here is a 100hp electric motor. I don't know if it is typical for an electric motor but damn the thing weighs over half a ton. I might make the 601XL a little nose heavy. But it's priced right up there with a Lyc of equal power. http://www.baldor.com/products/detai...neralPur pose Catalog Number: D50100P Description: STOCK MOTOR,368AT,100HP,1750/2000RPM,DPFG Ship Weight: 1,118 lbs. List Price: $21,195 Multiplier Symbol: N2 |
#59
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Electrically Powered Ultralight Aircraft
Gig 601XL Builder wrote:
Larry Dighera wrote: On Tue, 07 Aug 2007 19:14:59 GMT, wrote in : If you go to http://xtronics.com/reference/energy_density.htm you find the energy densities of a lot of things. Propane (liquid) 13,900 Wh/kg Diesel 13,762 Wh/kg gasoline 12,200 Wh/kg Ethanol 7,850 Wh/kg Methanol 6,400 Wh/kg Secondary Lithium - ion Polymer 130 - 1200 Wh/kg Primary Zinc-Air 300 Wh/kg Lead Acid Battery 25 Wh/kg So batteries have to improve by a factor of 10 to match gasoline. When you compare the efficiency of internal combustion Otto Cycle engines (30% - 40%) against electric motors (80% - 95%), it appears that a factor of five might be a more realistic comparison of their relative merits. Then there is the issue of power plant weight... Electric motors don't lose power in thin air either. With regard to reliability, electric motors have only one moving part compared to scores of moving parts for IC engines, their failure rate should be substantially greater than IC engines. Here is a 100hp electric motor. I don't know if it is typical for an electric motor but damn the thing weighs over half a ton. I might make the 601XL a little nose heavy. But it's priced right up there with a Lyc of equal power. http://www.baldor.com/products/detai...neralPur pose Catalog Number: D50100P Description: STOCK MOTOR,368AT,100HP,1750/2000RPM,DPFG Ship Weight: 1,118 lbs. List Price: $21,195 Multiplier Symbol: N2 Just a wild guess, but wouldn't this make for a very, very safe airplane?? George |
#60
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Electrically Powered Ultralight Aircraft
On Aug 7, 3:04 pm, "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net
wrote: Larry Dighera wrote: On Tue, 7 Aug 2007 14:51:55 -0500, "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in : all this talk of electric airplanes while a nice thought is something that at best is way in the future. That's only true if you overlook Randall Fishman's electrically powered ultralight (http://www.electraflyer.com) and Mr. Monnett's Sonex proof-of-concept Waiex aircraft (http://www.sonexaircraft.com/press/r...r_072407.html). But, I know, you were referring to electrically powered aircraft with the same utility as today's GA aircraft, right? Right. When the electric Sonex can do the same thing the VW powered Sonex can do then it will become something more than an interesting idea. I have not seen any significant flight duration claim on the Sonex, which speaks well for the design team. The 2 hours flight duration on the trike is IMO a gross exaggeration extrapolated from a much shorter actual time in thermal conditions. If the ability to get off the ground were the sole criteria we are there already but practical flight characteristics for mass consumption are way down the road. To be safe an aircraft needs a lot more power than the amount required to rise from the ground. My first home built ultralite was a 32 ft rigid wing using an IC engine of about 18hp and while it would fly the lack of climb ability was a big disadvantage. In marginal conditions it wouldn't lift beyond ground effect which resulted in interesting obstacle flights around trees and under power lines. It didn't take long for me to decide that my life was worth more than the 18hp engine and a new 30hp engine ultimately made for a much safer aircraft. |
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