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Prop torque question
On Oct 30, 2:27*pm, "Wilbur Hubbard"
wrote: "Joe" wrote in message ... On Oct 30, 1:20 pm, "Wilbur Hubbard" wrote: "Joe" wrote in message .... I'm hoping someone might have a refference site for free wheeling prop torque produced by a prop around the size of a 20X20 sailing at hull speed. (9kts) One goal on the boat we are designing and building will be an electric drive system and we are leaning towards a power phase 150 drive. http://www.uqm.com/propulsion_specs.php It's a 200 HP perm magnet motor, so as you sail and the prop turns it will generate power for the battery banks. These motors are now being used in electric hummers in the Army. They need 420 volt DC using two banks of batterys (35 batteries each bank) and will require 75 LBS or torque to generate electricity. Now I'm pretty sure the torque on a prop around the 22" size will be way over 75 lbs but do not know exactly. Im hoping it's twice that at least for gear reduction. So I'm hoping someone might have, or know where I can get data on prop torque. If not.... I guess I'm going to have to get a monkey wrench and a scale and find a boat of the proper size to test. Any suggestions? Joe So much for your original, dumb idea of commerce using sail only. Do you know how "green" huge lead/acid battery banks are? You might as well just run a diesel for your power and admit the folly of your original plan. Wilbur Hubbard- Hide quoted text - - Show quoted text - :: Battery banks can and are recycled. My goal has stayed the same Neal. :: That's not the point. There's the matter of disposing of the acid and recycling the lead takes lots of heat and this heat comes from OIL. Battery cases are made from OIL. Shipping the batteries to market takes OIL. Displaying the batteries in a retail or wholesale outlet relies on electricity and heat which takes, let me guess . . . OIL. So who do you think you are fooling with your electric motor fantasy? :: " The El Lago Coffee Company intends to show the world a model for :: sustainability and profit using 100% renewable energy. We will provide :: our customers with the greenest most delicious and eco-friendly :: products on the market" Tell me is isn't so, Joe! (thank you Sarah Palin) There is NO SUCH THING as 100% renewable energy. That's a myth. Even solar panels are not 100% renewable running off the sun. What do you think it took to produce them in the first place? Energy from, you got it. OIL! Yo Numb Nuts.. God gave us the wind and the sun, it's always going to blow and always going to shine......until the end of time. OIL IS GREAT. I worked in the patch most my life. So if you can use a gallon of oil to make a solar panel , our just burn it as fuel...what is the better use of the primary source of energy? :: Also a mission statement had been online as well :: :: "Our mission is to deliver high quality, high demand, naturally grown :: products shipped in a manner that fosters brand loyalty from our :: customers, and promotes environmental preservation. More pie-in-the-sky. Is it? We are growing fast here without much more than word of mouth. Lots of real sailors like a good adventure, good coffee at a price a deckhand can afford. :: With coffee being the second largest commodity traded on earth after :: oil, by reducing the oil used in transport coffee, we take an :: important step in reducing our dependence on middle eastern oil." The best way to reduce our dependence on middle eastern oil is to DRILL BABY DRILL and do it in the USA territory. Thats the fastest way. Is it the best long tern smart and stratigic way? :: GOT IT? Nope! Conservation just won't cut it. Increasing the local supply of oil is the only thing that will cut it. How's about both? :: Now that you know the basics let me clue you in. :: :: 1. :: We want to do a job, and will have many many days at sea with ZERO :: wind. :: Sitting still is OK if you have nothing better to do, and plenty of :: spare cash. That's what drove the last of the British windjammers from the seven seas.. Remember the Garthpool! She could not compete with the steamers. Steamers had a cheap source for fuel, emissions were not an issue. The oceans were clean, full of fish and not that crowded and exploited, and things change. :: 2. :: Houston is a big port with a very busy, narrow, and long shipping :: channel. I doubt the Pilot unions have a man that can tack a schooner :: up the channel without a breeze. So find a better port. Houston is just one of many. Find one you can actually sail into. Port Everglades for example. Houston is a designated Coffee port. Due to tax reasons and distrubition alone Houston is perfect. I can have a billion dollars worth of coffee and pay no property taxes on it at all...zero..nada... :: 3. :: Fuel is getting expensive and oil needs to be used more wisely than :: just burning it. We need to find ways of reducing demand to lower the :: cost. Yah, right. We conserve and reduce the cost and China and India buys all the more and negates any savings. Real smart, mon! I can not tell China what to do. And do not want to get in a bidding war to secure more fuel, I'd rather invest in Smart energy resources. We can build and develope it here in the USA. Now is the time. :: 4. I hate dealing with diesel. After a bloody week, cut ,burned, and :: then soaked in it, after a career of dealing with alge issues on just :: about every boat older than 15 years old, and again the high cost, i'd :: rather find a better way to have a nice long burst of energy at my :: finger tips. There isn't a better way or all commercial shipping would be using it already. The cost of fossel fuel will continue to rise and at some point the scale will tip. I'd rather be ahead of the curve neal. Thats the point. The only better way I can think of is the small nuclear reactors they plan to market in Japan. These might be the ideal solution for shipping. http://www.nextenergynews.com/news1/...shiba-micro-nu... they have issues, the russians did it on cargo ships long ago. :: It's called "auxiliary power" Neal. This type of unit could also :: generate the house power as well. The "primary power" and electric :: generation comes from the sails. Dream on. Do the math. It won't work. Done the math. :: On the issue of the bad side of acid and lead.. you have lead in your :: keel and its leeching out around cedar bucket cut and chicken bone :: reef as you type. Can you say, "cast iron?" Oh. I like cast Iron..makes since on a cheap boat. What about all the uric acid that surrounds your boat? :: *I would think a blow hard like you could see harnessing electric :: power from the sails a positive thing. Nice and quiet..ect.. Do the math. Not enough production capability spinning the prop and as the prop spins the forward speed decreases. If you harnessed ALL the power of the sails and turned it into electricity you might have enough to run your electric motor but then you would *need* to run your motor because the sails would not be making you go. All you need is to store 48 hr energy use at 100% power. According the the pilot charts the winds blow around 75% of the time between here and there over 10 kts. Three days gereration time for every day used at 100%. Then only plan on using 50% power most of the time. My prop was always spinning, and it slowing me down was never an issue. Even with the shaft chained down it had little effect on slowing the boat..at all. And as a back up to the back up Solar panels on the cargo hold and a couple of wind gens. maybe a capstone micro turbine generator for emergency power. Wish I could start building now, with all the new energy stimilus money uncle sam is investing that could pay for around 30% of the construction cost. Joe Wilbur Hubbard- Hide quoted text - - Show quoted text - |
#2
posted to rec.boats.cruising
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Prop torque question
Joe wrote:
I'm hoping someone might have a reference site for free wheeling prop torque produced by a prop around the size of a 20X20 sailing at hull speed. (9kts) It's a 200 HP perm magnet motor... They need 420 volt DC using two banks of batterys (35 batteries each bank) and will require 75 LBS or torque to generate electricity. Now I'm pretty sure the torque on a prop around the 22" size will be way over 75 lbs but do not know exactly. Im hoping it's twice that at least for gear reduction. A SWAG for you: the MOST efficient a fluid mill gets, is to extract the kinetic energy represented by halving the fluid's speed. The energy in question is given by prop area (diam 20 inches) and effective speed 4.5 kts. Now: reduce the units to easy SI units: 4.5 kts = 2.3 m/s diameter of water column: 20 ins = 0.51 m volume of water/sec = 2.3 X pi X 0.51^2 / 4 = 0.47 cu meters density of water 1050 kg /m^3 (for salt water say...) Mass flow rate: 0.47 X 1050 kg/sec = 489 kg/sec Force times speed = power So power = 489 kg/sec X 9.8 N/kg = 4797 watts. Let's suppose 50% transfer efficiency and we end up with 2.4 kW to play with, at hull speed. Finding a prop speed 10 % less than the no slip speed of a 20 /20 prop, and knowing the available power from above, leads easily to the torque available... Brian W |
#3
posted to rec.boats.cruising
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Prop torque question
On Oct 31, 12:10*pm, brian whatcott wrote:
Joe wrote: I'm hoping someone might have a reference site for free wheeling prop torque produced by a prop around the size of a 20X20 sailing at hull speed. (9kts) It's a 200 HP perm magnet motor... They need 420 volt DC using two banks of batterys (35 batteries each bank) and will require 75 LBS or torque to generate electricity. Now I'm pretty sure the torque on a prop around the 22" size will be way over 75 lbs but do not know exactly. Im hoping it's twice that at least for gear reduction. A SWAG for you: the MOST efficient a fluid mill gets, is to extract the kinetic energy represented by halving the fluid's speed. The energy in question is given by prop area (diam 20 inches) and effective speed 4.5 kts. Now: reduce the units to easy SI units: 4.5 kts *= 2.3 m/s diameter of water column: 20 ins = 0.51 m volume of water/sec = 2.3 X pi X 0.51^2 / 4 = 0.47 cu meters density of water *1050 kg /m^3 (for *salt water say...) Mass flow rate: 0.47 X 1050 kg/sec = 489 kg/sec Force times speed = power So power = 489 kg/sec X 9.8 N/kg = 4797 watts. Let's suppose 50% transfer efficiency and we end up with 2.4 kW to play with, at hull speed. Finding a prop speed 10 % less than the no slip speed of a 20 /20 prop, and knowing the available power from above, leads easily to the torque available... Brian W Thanks Brian, I can use this data and go back to the company and talk to an applications engineer. Joe |
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