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#1
March 16th 04, 07:31 AM
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turbine propeller
Hi I'm working on an aviation project...a motorized paraglider fan
specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop... 
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#2
March 16th 04, 09:02 AM
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If the wind-mill fan is correctly engineered to be wind-driven it is unlikly
good as propeller. A propeller have the convex side in the direction of flight, and the round leading edge in direction of rotation, and the pitch .... Jan Carlsson www.jcpropellerdesign.com "sebastian" skrev i meddelandet om... Hi I'm working on an aviation project...a motorized paraglider fan specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop...
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#3
March 17th 04, 12:56 AM
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"Jan Carlsson" wrote in message ...
If the wind-mill fan is correctly engineered to be wind-driven it is unlikly good as propeller. A propeller have the convex side in the direction of flight, and the round leading edge in direction of rotation, and the pitch .... Jan Carlsson www.jcpropellerdesign.com Definitely won't work, as Jan says. The blade camber is backward to a propeller's, since it it designed to convert thrust to rotation rather than rotation to thrust. I'd be worried about that turbine failing when driven by an engine. It is designed for more or less constant rotational speed, but a piston engine has powerful torque pulses that will cause failure of such light structures as a wind turbine fan. Airplane propellers are designed to withstand those forces. If your fan threw a blade, the vibration would rip the engine off your paraglider, and/or the remaining blades might do serious damage to you or the machine. Dan "sebastian" skrev i meddelandet om... Hi I'm working on an aviation project...a motorized paraglider fan specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop...
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#4
March 17th 04, 07:09 AM
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Yeah, maybe you should try one of those egg-beater windmills instead. Won't
get you anywhere, but you'll win with the "cool factor". Pete
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#5
March 17th 04, 07:18 AM
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Well spoken Dan Thomas,
I wanted Sebastian to see and come to an understanding of the difference him self. Even if it was a airplane propeller that was used as wind mill, (just as wrong) it is the wrong way to start with the propeller, then put an engine and aircraft to the propeller. It have to be a careful process picking out a propeller to suit the engine AND airplane, when correct you can fine tune the purpose of the propeller a few inch in diameter and pitch, depending on if you want a good climb or cruise or something in between. Jan Carlsson "Dan Thomas" skrev i meddelandet om... "Jan Carlsson" wrote in message ... If the wind-mill fan is correctly engineered to be wind-driven it is unlikly good as propeller. A propeller have the convex side in the direction of flight, and the round leading edge in direction of rotation, and the pitch .... Jan Carlsson www.jcpropellerdesign.com Definitely won't work, as Jan says. The blade camber is backward to a propeller's, since it it designed to convert thrust to rotation rather than rotation to thrust. I'd be worried about that turbine failing when driven by an engine. It is designed for more or less constant rotational speed, but a piston engine has powerful torque pulses that will cause failure of such light structures as a wind turbine fan. Airplane propellers are designed to withstand those forces. If your fan threw a blade, the vibration would rip the engine off your paraglider, and/or the remaining blades might do serious damage to you or the machine. Dan "sebastian" skrev i meddelandet om... Hi I'm working on an aviation project...a motorized paraglider fan specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop...
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#6
March 17th 04, 09:03 PM
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ah well, that was exactly the type of feeback i was looking for
thanks. My revised plan is to experiment with building a carbon fiber propeller. I like the general design theory behind the wind turbine that i specified, so I am thinking of inverting the pitch for thrust and making the blade shorter and broader (45-50" diameter, 2-4" wide tapering to tip). My plan is to make foam airfoil cores with a hotwire cutter, extensively reinforce the lengthwise direction with unidirectional carbon fiber roving, and wrap the whole blade with carbon fiber farbric and vacuum bag. I would use a similar twisting geometry that narrows and goes from ~20 degrees to nearly a flat pitch at the tip and transforms from an elipitcal cross section at the hub to an airfoil at the tip. or would it be better and simpler to have a constant pitch, width, and airfoil and make the overall pitch ground adjustable. Rememeber i need it to be as light and efficent as possible this is for a paraglider fan (backpack type) not some big beefy airplane. Any suggestions? "Jan Carlsson" wrote in message ... Well spoken Dan Thomas, I wanted Sebastian to see and come to an understanding of the difference him self. Even if it was a airplane propeller that was used as wind mill, (just as wrong) it is the wrong way to start with the propeller, then put an engine and aircraft to the propeller. It have to be a careful process picking out a propeller to suit the engine AND airplane, when correct you can fine tune the purpose of the propeller a few inch in diameter and pitch, depending on if you want a good climb or cruise or something in between. Jan Carlsson "Dan Thomas" skrev i meddelandet om... "Jan Carlsson" wrote in message ... If the wind-mill fan is correctly engineered to be wind-driven it is unlikly good as propeller. A propeller have the convex side in the direction of flight, and the round leading edge in direction of rotation, and the pitch .... Jan Carlsson www.jcpropellerdesign.com Definitely won't work, as Jan says. The blade camber is backward to a propeller's, since it it designed to convert thrust to rotation rather than rotation to thrust. I'd be worried about that turbine failing when driven by an engine. It is designed for more or less constant rotational speed, but a piston engine has powerful torque pulses that will cause failure of such light structures as a wind turbine fan. Airplane propellers are designed to withstand those forces. If your fan threw a blade, the vibration would rip the engine off your paraglider, and/or the remaining blades might do serious damage to you or the machine. Dan "sebastian" skrev i meddelandet om... Hi I'm working on an aviation project...a motorized paraglider fan specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop...
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#7
March 18th 04, 12:18 AM
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A constant pitch will be better then a constant angle and blade width.
The Q is what Pitch, what Diameter, what Aspect Ratio, what nr of blades? The questions is the same whatever it is a one meter model plane, back pak or a turbo-prop. Jan Carlsson "sebastian" skrev i meddelandet om... ah well, that was exactly the type of feeback i was looking for thanks. My revised plan is to experiment with building a carbon fiber propeller. I like the general design theory behind the wind turbine that i specified, so I am thinking of inverting the pitch for thrust and making the blade shorter and broader (45-50" diameter, 2-4" wide tapering to tip). My plan is to make foam airfoil cores with a hotwire cutter, extensively reinforce the lengthwise direction with unidirectional carbon fiber roving, and wrap the whole blade with carbon fiber farbric and vacuum bag. I would use a similar twisting geometry that narrows and goes from ~20 degrees to nearly a flat pitch at the tip and transforms from an elipitcal cross section at the hub to an airfoil at the tip. or would it be better and simpler to have a constant pitch, width, and airfoil and make the overall pitch ground adjustable. Rememeber i need it to be as light and efficent as possible this is for a paraglider fan (backpack type) not some big beefy airplane. Any suggestions? "Jan Carlsson" wrote in message ... Well spoken Dan Thomas, I wanted Sebastian to see and come to an understanding of the difference him self. Even if it was a airplane propeller that was used as wind mill, (just as wrong) it is the wrong way to start with the propeller, then put an engine and aircraft to the propeller. It have to be a careful process picking out a propeller to suit the engine AND airplane, when correct you can fine tune the purpose of the propeller a few inch in diameter and pitch, depending on if you want a good climb or cruise or something in between. Jan Carlsson "Dan Thomas" skrev i meddelandet om... "Jan Carlsson" wrote in message ... If the wind-mill fan is correctly engineered to be wind-driven it is unlikly good as propeller. A propeller have the convex side in the direction of flight, and the round leading edge in direction of rotation, and the pitch .... Jan Carlsson www.jcpropellerdesign.com Definitely won't work, as Jan says. The blade camber is backward to a propeller's, since it it designed to convert thrust to rotation rather than rotation to thrust. I'd be worried about that turbine failing when driven by an engine. It is designed for more or less constant rotational speed, but a piston engine has powerful torque pulses that will cause failure of such light structures as a wind turbine fan. Airplane propellers are designed to withstand those forces. If your fan threw a blade, the vibration would rip the engine off your paraglider, and/or the remaining blades might do serious damage to you or the machine. Dan "sebastian" skrev i meddelandet om... Hi I'm working on an aviation project...a motorized paraglider fan specifically...and i had a question about using a wind turbine as the propeller The one on this page is the one im thinking of using: http://www.hydrogenappliances.com/bladekits.html Its some kind of plastic reinforced carbon fiber with ~60" diameter. Six blades. Its supposed to be good up to several thousand rpm and has a 70 year outdoor weather rating...so im guessing its reasonably tough...not bad for $89. My main question is will it work as a propeller to generate enough thrust...say 50-100lbs...im going to be able to supply it with ~15hp...(@2000-3000rpm) it seems to have a quite interesting blade geometry...near the hub it has an eliptical cross section with a wide base and a severe pitch... as the blade proceeds out to the tip it goes COMPLETELY flat (no pitch) but in cross section it has a lovely airfoil with a flat side (bottom of wing) and a curved airfoil on the other side (top of wing)...for the wind turbine application use they indicate to put the flat side of the airfoil facing the wind...which way should I orient the flat side if I want to use it for thrust...how would I make thrust calculations or even better measure thrust directly? Will the flexabilty of the prop be stabilized by centripital force even when under load (pushing my 180lb body under a paraglider wing) i.e. will the prop remain reasonably flat if spinning fast enough and not bend and hack my legs/head off....it seems like it is really well engineered from a aeronautics standpoint...i would probalbly make a custom heavy duty hub so please focus replies on the blades...thanks...more generally have any of you used 5/6 blade props on an ultralight? id be interesting in hearing your impressions of how well it worked for you compared to a 2/3/4 blade prop...
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#8
March 18th 04, 12:44 PM
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#9
March 18th 04, 04:30 PM
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then youre saying the best way to answer the questions
is...empirically. or can i make decisions a priori about prop geometry based on my input power (15hp) and rpm (2500)? it would seem that long non twisting, tapered, symetric airfoil blades that are ground adjustable in pitch and varied in the nr of blades on the hub would be the better way since the the variables of pitch, diameter(shortening), & nr of blades could be experimented with and optimized. I suppose under these circumstances all effort should be put into aspect ratio since that is the one varibale that would be most difficult to vary and test. so with that said, any advice on choosing an aspect ratio for my purpose? and as a i vary these parameters...how do i measure changes in thrust directly...attach my motor to a scale somehow? "Jan Carlsson" wrote in message ... A constant pitch will be better then a constant angle and blade width. The Q is what Pitch, what Diameter, what Aspect Ratio, what nr of blades? The questions is the same whatever it is a one meter model plane, back pak or a turbo-prop. Jan Carlsson "sebastian" skrev i meddelandet om... ah well, that was exactly the type of feeback i was looking for thanks. My revised plan is to experiment with building a carbon fiber propeller. I like the general design theory behind the wind turbine that i specified, so I am thinking of inverting the pitch for thrust and making the blade shorter and broader (45-50" diameter, 2-4" wide tapering to tip). My plan is to make foam airfoil cores with a hotwire cutter, extensively reinforce the lengthwise direction with unidirectional carbon fiber roving, and wrap the whole blade with carbon fiber farbric and vacuum bag. I would use a similar twisting geometry that narrows and goes from ~20 degrees to nearly a flat pitch at the tip and transforms from an elipitcal cross section at the hub to an airfoil at the tip. or would it be better and simpler to have a constant pitch, width, and airfoil and make the overall pitch ground adjustable. Rememeber i need it to be as light and efficent as possible this is for a paraglider fan (backpack type) not some big beefy airplane. Any suggestions?
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#10
March 18th 04, 06:05 PM
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Sebastian,
With data on both engine and speed it is easy to calculate an propeller. I sugest you make a wood propeller first, then you can see how much prop you need, The Idea is to "load" the engine so you get the desired RPM, with the most optimum prop you can get at the design "point" (speed) Even if it is calculated correctly there can be unknown factors, like if the engine turn out 2 HP more or less!? Then it is easy quick and cheep to make a new wood propeller The blade have to be twisted, you have to know the differens of Pitch and Angle, an prop with uniform pitch along the blade have the blade twisted to higher angle closer to the hub. Even with reduced pitch near the hub, the angle is normaly higher there. With the Prop behind the back(pack) It will work in turbulant air, specially near the hub it will be "dead" air, closer to the tip it will work in the "aircrafts" forward speed + the induced air (air sucked in) The Induced airspeed will be large compered to forward speed. What is the normal Climb speed, Cruise speed and top speed for a paramotor? Jan Carlsson www.jcpropellerdesign.com "sebastian" skrev i meddelandet om... then youre saying the best way to answer the questions is...empirically. or can i make decisions a priori about prop geometry based on my input power (15hp) and rpm (2500)? it would seem that long non twisting, tapered, symetric airfoil blades that are ground adjustable in pitch and varied in the nr of blades on the hub would be the better way since the the variables of pitch, diameter(shortening), & nr of blades could be experimented with and optimized. I suppose under these circumstances all effort should be put into aspect ratio since that is the one varibale that would be most difficult to vary and test. so with that said, any advice on choosing an aspect ratio for my purpose? and as a i vary these parameters...how do i measure changes in thrust directly...attach my motor to a scale somehow? "Jan Carlsson" wrote in message ... A constant pitch will be better then a constant angle and blade width. The Q is what Pitch, what Diameter, what Aspect Ratio, what nr of blades? The questions is the same whatever it is a one meter model plane, back pak or a turbo-prop. Jan Carlsson "sebastian" skrev i meddelandet om... ah well, that was exactly the type of feeback i was looking for thanks. My revised plan is to experiment with building a carbon fiber propeller. I like the general design theory behind the wind turbine that i specified, so I am thinking of inverting the pitch for thrust and making the blade shorter and broader (45-50" diameter, 2-4" wide tapering to tip). My plan is to make foam airfoil cores with a hotwire cutter, extensively reinforce the lengthwise direction with unidirectional carbon fiber roving, and wrap the whole blade with carbon fiber farbric and vacuum bag. I would use a similar twisting geometry that narrows and goes from ~20 degrees to nearly a flat pitch at the tip and transforms from an elipitcal cross section at the hub to an airfoil at the tip. or would it be better and simpler to have a constant pitch, width, and airfoil and make the overall pitch ground adjustable. Rememeber i need it to be as light and efficent as possible this is for a paraglider fan (backpack type) not some big beefy airplane. Any suggestions?
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