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SteveH
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« Reply #885 on: November 27, 2009, 07:34:38 PM » |
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Tend to agree Outasight... I would have thought the last thing you would want is a vortex with all that spinning air causing drag....   I don't understand this pastry cutter stuff either....  At least it seems to have had a little thought applied in some area's...  Might need to be a little further to the rear of the pivot point though, for stable wind finding....  Nice bit of animation... Slightly better than "Dumbo" (Disney®) & almost as believable....  |
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Preveli, South Crete.
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noelsquibb
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« Reply #886 on: November 28, 2009, 12:18:54 AM » |
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Then I read the link to the Dragonfly (also vapourware) turbine that even suggested that it could run on a windless day! Get this... they said it would use solar panels to charge batteries to spin up the front ring of the turbine to provide the wind that would spin the rear sets and turn the generator to make electricity!!! Ha oh dear and there was me getting all excited over a jet propelled swindlesave. I wonder if they have actually attracted funding as claimed, or if they are kite flying in the hope of pulling someone in ? thanks for the heads up Outtasight |
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mmmmm, gravy
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Panda_Badger
Full Member
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Posts: 104
Spring Panda
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« Reply #887 on: November 28, 2009, 08:15:31 PM » |
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« Last Edit: November 28, 2009, 08:18:40 PM by Panda_Badger »
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Row, row, row yer boat gently down the stream......
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biff
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« Reply #888 on: November 29, 2009, 09:00:09 PM » |
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nsu quickly,  tears in my eyes,,,sniff,,sniff,sniff,nuffin quick about the nsu quickly, got very fit pushing it and hopping on then peddling like a lunatic,paid 4quid for it,broke down on the way home, no paper work, nuffin et all,cops came along, looking for tax,et insurance,etc, had nuffin, but they laughed and laughed at me,me standing there soaked in the rain, boiling hot from trying to start it,they said it was harmless and could,nt be classed as a vehicle of any description and let me off as i promised to get rid of it,,,which i did, nsu quickly,,sniff,, sniff sniff,,, biff. |
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SteveH
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« Reply #889 on: November 29, 2009, 09:31:37 PM » |
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Now that's a sensible idea, but not exactly radical.... It works in the same way as the small vertical fins that are now affixed to almost all commercial airliners wing tips. Effectively they prevent air spilling uncontrollably from an area of high pressure into a lower pressure area & dramatically reduce turbulence at the wing/blade tip. Before this was done to the wings on commercial airlines they would produce a tip vortex that would persist for many miles, in the case of the 747 it caused several crashes of light aircraft following them in to land. By adding the small wing tip fins, it almost eliminates the trailing vortex & the associated drag making the wing up to 5% more efficient & reducing fuel consumption accordingly... often wondered why the large turbine blades didn't have something similar. |
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Preveli, South Crete.
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northern installer
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« Reply #890 on: November 29, 2009, 09:44:32 PM » |
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nsu quickly, tears in my eyes,,,sniff,,sniff,sniff,nuffin quick about the nsu quickly, got very fit pushing it and hopping on then peddling like a lunatic,paid 4quid for it,broke down on the way home, no paper work, nuffin et all,cops came along, looking for tax,et insurance,etc, had nuffin, but they laughed and laughed at me,me standing there soaked in the rain, boiling hot from trying to start it,they said it was harmless and could,nt be classed as a vehicle of any description and let me off as i promised to get rid of it,,,which i did, nsu quickly,,sniff,, sniff sniff,,, biff. Biff,you were sold a pup! try this:neighbouring boy had an nsu quickly,being only 15 we took it to a works private road at the weekend,and had a fine old time trying to emulate geoff duke;this went on for several weekends,until disaster struck twice over,we were ejected by the watchman,and the drive sprocket came off.We pushed it home and stripped the engine in neighbouring boy's washhouse;his mum threw a wobbly,so he sold me it for 5/-.Just as I was taking the last nuts and bolts,his father asked what was going on...5/-...? thats far too much,its broken,give him 2/6 back this instant!...Back in our shed,I made a new woodruff key hacksawn from round bar and filed to size,lapped the sprocket to its taper with grinding paste,and by sunday...zing...ding ...ding ...ding up and down the allotments (until asked to stop!!)Next day,a schoolfriend, just 16 and eager for economy class travel,offered his £10 savings if it passed an mot,it did,and he was still riding it around 6 months later,so Nsu quickly? name might have been misleading,butwhat fun,with a profit at the end too. |
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"government scrappage scheme still available on Tardis trade ins (dont ask how we get around the deadline...)"
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frotter
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« Reply #891 on: November 29, 2009, 10:25:40 PM » |
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Mopeds = awesome fun for hairy-gonk teenagers.....  |
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HE WHO CONTROLS THE LARD - CONTROLS THE UNIVERSE!! Its me, incidentally..
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martin
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« Reply #892 on: November 29, 2009, 11:44:30 PM » |
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Mopeds? - cissified devices - real men started off on a Cyclemaster - 26cc, or the really fast rubber-burning 32cc version! Bought one for a princely £3 back in er um, back then..........  http://cyclemaster.wordpress.com/ |
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Unpaid volunteer administrator and moderator (not employed by Navitron) - Views expressed are my own - curmudgeonly babyboomer! - http://www.farmco.co.uk |
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northern installer
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« Reply #893 on: December 01, 2009, 03:03:18 PM » |
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aay up milad,did thou ev t'cap wi't peak on't back so thee goggles wid fit?
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"government scrappage scheme still available on Tardis trade ins (dont ask how we get around the deadline...)"
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frotter
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« Reply #894 on: December 01, 2009, 03:23:27 PM » |
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Nope - shiny metallic blue Nolan Guardsman lid. Soft southern jesse, see. |
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HE WHO CONTROLS THE LARD - CONTROLS THE UNIVERSE!! Its me, incidentally..
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biff
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« Reply #895 on: December 01, 2009, 08:54:59 PM » |
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yes sir, it was a pup indeedy.the next item was a lambretta 150,i have to addmitt it gave great service but was usless after the dance,especially if it was raining,i had terrible job getting wimmin onto it and when i stopped they would jump off and run away. jane my austin a30 was a real lady,good heater warm and dry, and ideal for sitting in out of the rain,extremely relaible.great for going dancing.it had a 4speed box with a long lethal gearstick. biff |
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Outtasight
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« Reply #896 on: December 02, 2009, 09:33:24 PM » |
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Now that's a sensible idea, but not exactly radical.... It works in the same way as the small vertical fins that are now affixed to almost all commercial airliners wing tips. Effectively they prevent air spilling uncontrollably from an area of high pressure into a lower pressure area & dramatically reduce turbulence at the wing/blade tip. Before this was done to the wings on commercial airlines they would produce a tip vortex that would persist for many miles, in the case of the 747 it caused several crashes of light aircraft following them in to land. By adding the small wing tip fins, it almost eliminates the trailing vortex & the associated drag making the wing up to 5% more efficient & reducing fuel consumption accordingly... often wondered why the large turbine blades didn't have something similar. I doubt it would scale up. The angle bits on the ends will probably just break off on a big rotor. The winglets on the aircraft wings don't experience any longitudinal force as the wing is moving forwards and not around. The L shape on the end of a rotating machine would experience large bending forces at the corner from its angular velocity in addition to the aerodynamic forces on the surface of the winglet. Any flexing of the winglet on a rotating machine will alter where the mass is and unbalance the thing. Sticking a lot of weight on the tip of a rotor that has usually been progressively tapered and lightened to stop it putting too much centripetal stress on the hub end of the blade will also mean building up the whole blade more to keep it rigid and then everything gets massively more expensive. We all remember the missiles of doom (tip mounted balance weights) on Frotter's machine and his subsequent mounting of them at the hub end to prevent repeat launches of gert lumps o' solder into space Still, on very small machines it may well be useful. I suspect what is also happening is that a current of air is deflected along the rotor and this would be "spin off" past the tip and its momentum just be lost in the wing tip vortex but by using that winglet to catch the current and channel it, the momentum of the air travelling along the rotor blade is captured by deflecting it and used to push the rotor a bit more. It would have been good to see the same experiment with smoke streamers. |
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KLD
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« Reply #897 on: December 02, 2009, 10:19:12 PM » |
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Why would it need to be L-shaped? Couldn't you have a T-shaped winglet? No bending forces, just a little more weight (to pull the blades straight:-) ?
Klaus
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SteveH
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« Reply #898 on: December 02, 2009, 10:25:00 PM » |
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It would have been good to see the same experiment with smoke streamers.
With you most the way.... & agree about the tip channeling that would also prevent pressure spill + it would remove tip vortices's @ the same time + the associated drag. But if you are making the blade more efficient & reducing the drag then you can shorten the blade & reduce a lot of the other stress problems also. Birds have been handling this problem for millenia & turbines work in the same speed range... maybe worth looking to nature.... Smoke streamers & strobed synchronous visible laser light... |
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Preveli, South Crete.
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SteveH
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« Reply #899 on: December 02, 2009, 10:33:05 PM » |
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Why would it need to be L-shaped? Couldn't you have a T-shaped winglet? No bending forces, just a little more weight (to pull the blades straight:-) ?
Klaus
Yes Klaus, that would work.... Clearing the tower is the only problem. I have noticed that the it appears that a few of the newer large, commercial VAWT's have their rotor axis pitched upwards & the lighter, thinner blades seem to curve forwards... anybody else noticed this? |
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Preveli, South Crete.
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