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#101
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Electrically Powered Ultralight Aircraft
Recently, Larry Dighera posted:
On Tue, 07 Aug 2007 17:51:27 GMT, "Neil Gould" wrote in : Recently, Larry Dighera posted: [...] I'm thinking there would be necessity for some means of conducting the heat from the engine to a remote heat exchanger, and the resulting complexity and weight increase would negatively impact the potential advantages of a Stirling aviation engine. In any event, in addition to the Stirling engine and its fuel, a heat exchanger of some type needs to factored into the weight, cost, performance, and efficiency equations. Of course, but I don't see a lot of reason why that couldn't be incorporated into the overall design. My point is that heat exchangers need not be heavy, and could probably double as structural and/or aerodynamic components, further reducing (and possibly enhancing) their impact. How would you get the heat from the Stirling engine to the heat sink? If you use liquid coolant, it would be heavy and prone to leaks. I'm not a Stirling engine designer, so I can't answer that factually. I have been reading up on it a bit since the article was referenced in this thread, but I haven't seen such things as the required rate of dissipation for the engine to work efficiently. If the heat sink needs to be large and close to the engine, perhaps a design where the engine is mounted on or even incorporated into the wing is a way to go. There might be one advantage to using Sterling external combustion engines for aviation: the use of atomic energy as a fuel source if the weight of the lead shielding were not too great. Imagine an aircraft that effectively never runs out of fuel! There'd be no more fuel exhaustion mishaps. One downside would be the hazardous materials that could be dispersed in a crash. There are a lot of down sides to atomic power, but NASA uses it to power Stirling engines in space. Understandable, but their expectation is that catastrophic destruction would disperse the nuclear material harmlessly. That can't be presumed for light aircraft. If the rocket detonated in the atmosphere, it might not be so harmless. I don't see why it would be nearly as bad as a "dirty bomb" would be, as the material would be dispersed over a pretty large area. I would guess the reactor is jacketed with sufficient strength to preclude its destruction. My guess is that NASA et al are just hoping for good fortune. Having a reactor land from orbit intact in the middle of a city wouldn't be all that desirable. ;-) So, my bet is on there being no good plan for dealing with such a catastrophe *other* than wide dispersal of the nuclear material or the luck of landing in the ocean. Not that *that* outcome is desirable either... Neil |
#102
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Electrically Powered Ultralight Aircraft
"Larry Dighera" wrote in message ... I would think that would be close to the bare minimum. I flew a fixed wing hang glider on 10 HP for a while back in the 70s. A Manta Fledgling, and it was very underpowered. Maybe 100 fpm climb or so. I would guess the rigid wing would have a higher L/D than a powered parachute's 4:1, so it might require less power. Does that sound correct in your experience? Indeed, quite a bit less from my experience. I think my Fledge was supposed to be around 10:1. |
#103
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Electrically Powered Ultralight Aircraft
On Tue, 07 Aug 2007 14:58:07 GMT, Larry Dighera
wrote: If a 14 HP electric propulsion system weighing 46 lbs could be constructed, apparently it would permit the use of PPGs by pilots up to 180 lbs. A PPG is a LOT more efficient than a powered parachute (PPC), but still far less efficient than a rigid wing. Still, several electric PPG's have been flown. The primary goal here is noise and vibration reduction, a worthy goal when the engine is strapped to the pilot's back. The major problem is the weight of the batteries, still far heavier than gasoline. Also the lithium polymer batteries used are still quite expensive (over $10,000 for enough for a half hour flight) and somewhat dangerous (sort them out and they can explode!) -Dana -- -- If replying by email, please make the obvious changes. ------------------------------------------------------------------------------- The number of elected federal officials is limited to congress, the president and the vice president. That's only 537 people. The federal bureaucracy numbers in the millions..... |
#104
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Electrically Powered Ultralight Aircraft
"Dana wrote The major problem is the weight of the batteries, still far heavier than gasoline. Also the lithium polymer batteries used are still quite expensive (over $10,000 for enough for a half hour flight) and somewhat dangerous (sort them out and they can explode!) Damn straight! No way am I going to strap a bunch of lithium polymer batteries to my butt. Some of the newer Lithium iron cells, maybe, but they also cost a LOT more. Still, electric flight, like many have said, still have a way to go. -- Jim in NC |
#105
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Electrically Powered Ultralight Aircraft
Morgans wrote:
"Dana wrote The major problem is the weight of the batteries, still far heavier than gasoline. Also the lithium polymer batteries used are still quite expensive (over $10,000 for enough for a half hour flight) and somewhat dangerous (sort them out and they can explode!) Damn straight! No way am I going to strap a bunch of lithium polymer batteries to my butt. Some of the newer Lithium iron cells, maybe, but they also cost a LOT more. Still, electric flight, like many have said, still have a way to go. And as if we need more proof of this. TOKYO: Japan's Toyota Motor Corp. will delay by one or two years the rollout of new high-mileage hybrids with lithium-ion batteries because of safety concerns, reported a newspaper. Toyota's decision was prompted by worries that the batteries could overheat, catch fire or even explode, the Wall Street Journal on Thursday reported in its online edition, quoting unnamed Toyota executives. |
#106
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Electrically Powered Ultralight Aircraft
On Thu, 09 Aug 2007 23:13:55 -0400, Dana M. Hague
d(dash)m(dash)hague(at)comcast(dot)net wrote in : On Tue, 07 Aug 2007 14:58:07 GMT, Larry Dighera wrote: If a 14 HP electric propulsion system weighing 46 lbs could be constructed, apparently it would permit the use of PPGs by pilots up to 180 lbs. A PPG is a LOT more efficient than a powered parachute (PPC), but still far less efficient than a rigid wing. Still, several electric PPG's have been flown. The primary goal here is noise and vibration reduction, a worthy goal when the engine is strapped to the pilot's back. The major problem is the weight of the batteries, still far heavier than gasoline. Also the lithium polymer batteries used are still quite expensive (over $10,000 for enough for a half hour flight) and somewhat dangerous (sort them out and they can explode!) -Dana That's interesting information. Thank you. It sounds like you have quite a bit of experience in this area. Are you able to provide links to any forums or web sites related to this topic? |
#107
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Electrically Powered Ultralight Aircraft
Gig
Just saw where GM bought a battery company here in US that has developed batteries that do not catch fire or expload like current Lithium Polymer's. GM expects to have a plug in auto on market at least two years before Toyota can get their batteries sorted out and their auto on the market. Big John ************************************************* On Fri, 10 Aug 2007 11:37:39 -0500, "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote: Morgans wrote: "Dana wrote The major problem is the weight of the batteries, still far heavier than gasoline. Also the lithium polymer batteries used are still quite expensive (over $10,000 for enough for a half hour flight) and somewhat dangerous (sort them out and they can explode!) Damn straight! No way am I going to strap a bunch of lithium polymer batteries to my butt. Some of the newer Lithium iron cells, maybe, but they also cost a LOT more. Still, electric flight, like many have said, still have a way to go. And as if we need more proof of this. TOKYO: Japan's Toyota Motor Corp. will delay by one or two years the rollout of new high-mileage hybrids with lithium-ion batteries because of safety concerns, reported a newspaper. Toyota's decision was prompted by worries that the batteries could overheat, catch fire or even explode, the Wall Street Journal on Thursday reported in its online edition, quoting unnamed Toyota executives. |
#108
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Electrically Powered Ultralight Aircraft
GM on the cutting edge of anything is a little funny. And I'm sure Sony
didn't think their batteries would do this... http://www.youtube.com/watch?v=WeWq6rWzChw Is this the story you are talking about John? If so what is an "LG Chem cell?" http://www.autobloggreen.com/2007/06...cts-for-chevy/ Big John wrote: Gig Just saw where GM bought a battery company here in US that has developed batteries that do not catch fire or expload like current Lithium Polymer's. GM expects to have a plug in auto on market at least two years before Toyota can get their batteries sorted out and their auto on the market. Big John ************************************************* |
#109
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Electrically Powered Ultralight Aircraft
Gig 601XL Builder wrote AND THEN HIT THE SEND KEY BEFORE HE MEANT TO:
GM on the cutting edge of anything is a little funny. And I'm sure Sony didn't think their batteries would do this... http://www.youtube.com/watch?v=WeWq6rWzChw Is this the story you are talking about John? If so what is an "LG Chem cell?" http://www.autobloggreen.com/2007/06...gm-awards-two- battery-development-contracts-for-chevy/ GM doing this also kind of proves my point that the new battery technology is coming from somewhere with a lot more money in play than the ultralight and LSA market. |
#110
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Electrically Powered Ultralight Aircraft
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message ... Gig 601XL Builder wrote AND THEN HIT THE SEND KEY BEFORE HE MEANT TO: GM on the cutting edge of anything is a little funny. And I'm sure Sony didn't think their batteries would do this... http://www.youtube.com/watch?v=WeWq6rWzChw Is this the story you are talking about John? If so what is an "LG Chem cell?" http://www.autobloggreen.com/2007/06...gm-awards-two- battery-development-contracts-for-chevy/ GM doing this also kind of proves my point that the new battery technology is coming from somewhere with a lot more money in play than the ultralight and LSA market. "LG" is Lucky Goldstar, a Korean conglomerate. |
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