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Forum Index : Windmills : The "Ax Fx - & - F&P Dual"
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fillm Guru  Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi All I now have the two mills up and flying as you can see in the pic above , I was origionally going to title this thread as " The Ax Fx - Vs - F&P Dual " but decided to not pit one against the other as they are two entirely different machines with completly different costs and engineering involved in construction.. I would rather just give the basic data and details of what the two machines are doing in output and performance and anyone who reads this can make their own conclusions on what path they would like to go on .. Firstly both mills are setup for a 48V system as all my power goes back into the Grid via a Latronics PVE 1200 . The basic concept for the Ax Fx was worked out by Gordon and is specificly designed to have a cut in of arround 200 Rpm and uses a Capacitor bank and Voltage doubler arangment to allow a cut in of 100Rpm , the blades are 3.25m and are the PVC evtrusions available through the links on this site, if more info on the way it was all built and assembled then search for Homegrown Ax Fx .. The F&P Dual has been a work in progress over the last two years with many different changes to get to where it is today , the stators are 80s configured as 2p7s and both have been declogged bu twisting the poles , they . One in star and one in delta , both with their own cap banks and seperate voltage doublers that give a cut in of 100Rpm (star) 150Rpm (delta) , the blades are 3.15m and the same PVC extusion. I dont think it can get much better than where it is at present , The F&P starts up in arround 8klm and will produce power in anything over 6-7klm and in wind up to approx 15klm there is almost no difference in output , but the Ax Fx doesn't stop unless the wind stops and is ready to catch any available power while the F&P is still getting up to cut in speed , that is the big light wind difference . Between 8 to15 so far the F&P seemes to be a slightly better in output and then it all changes as the wind keeps increasing as you can see from the piclog max readings below.. 
Where it all gets pear shaped with the F&P if you dont have your furling set up properly is after 500Rpm where the core becomes saturated and the torque curve is droping and there is basicly very little additional power that can be produced with out getting into a dangerous situation as in an out of controll wind mill as happened here as you can see 750Rpm @ 735W in 50+Klm . The F&P can not be stoped by shorting the coils in this wind only a mechanical brake would stop it or worse still, total destruction.. All in all a pretty good test for the PVC blades with concerns from some that they can't get up to high speed .. I have now increased the offset and it is furling in 35Klm as I don't want this happening again as shown in a pic of what was starting to happen to the rivit holes holding the blades to the tubes.. 
The max read outs for the Ax Fx speak for themselves 2500W @ 480Rpm in the same 50+Klm , the point where it was all getting out of controll with the grid inverter maxed the dump load maxed and batt voltage still rising , the switch was thrown and it stopped . I would at this point like to thank Gordon for all the work, caculations and advice he has done to help 
Dual piclog , reading both mills at the same time . 
Elec box for the Ax Fx 
A good reason to have your furling set right , approx 1mm of movement . Overspeed will take its toll on any blade and mounting system ! 750Rpm is fairly hooting for a 3.150m set of blades More will come as time goes on ...Phill.. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Phill, I think this exercise shows how important it is to size a windmill for the available wind profile at a location. The Dual AxFx mill would suit high wind areas. In low wind areas, it probably would not matter. The poor electrical braking characteristics of the F&P mill are not good in areas with high winds. My own F&P mill was able to overpower the electrical brake last night. The inductance limiting also appears to be more of a problem with a decogged F&P. You have made a very professional finish to your setup. I will need to smarten my act now. I hope this inspires others to try the cap doublers as well, as they seem to work on low pole count mills as well with good effect. May need to look at the power curves, to see the full story. Gordon. become more energy aware |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Well Phil, You'd have to feel pretty happy to see multi kilowatts coming out of the axial flux. It is a step up from the F&P with it's inductive limiting and 300 odd watts per stator. It's all about matching the loads, and this is a good example of how flexible the TSR is with the two different styles of mill.... although 700+ rpm is starting to get exciting. I do like the braking effect of the axial, and the raw power of low resistance windings, but the F&P is a clear winner with simplicity and ease of build. It won't set the world on fire, but it will do a creditable job (until you get to build an axial) of converting wind to power. It is interesting to see the axial doing slightly less than the F&P in the 8-15 kph. I suspect it is because you wound for the high cut in (in order to use the caps to then lower cutin). If it was wound for stall operation, you would never see the 2.5kw, but would get better 5-20kph performance. I would wind for late cut in as well (as I have for 48v), as you can get high power and lower temperature stators.... and instant stop to boot. With your limited cooling, you have done the best thing in my humble opinion. Very nice to see... and I bet you have trouble wiping the smile off when you see the amp gauge wound off the clock 
..........oztules ps look forward to seeing Gordons unit as well..... Village idiot...or... just another hack out of his depth |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Good work Phill and Gordon. Great to see a new alternator design becoming a reality. The F&P is a great little unit for smaller windmills in the 50 to 300 watt range, its easy to use and a cheap build. However it has serious shortcommings with low wind startup and power levels over 500 watts, even with dual stators. This new axial flux machine is a serious windmill! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
It definitely does bring a smile to my face Oz when the wind picks up and all the leds are glowing on the grid inverter , as Glenn has said "this is a serious windmill" and it is a credit to Gordon . The other thing the two mills show is the versitility of the PVC blades and that having a constant pitch can deliver the power in low and high wind , although it would be good to trial other types of blades as time goes on. As you said Oz the instant shut down is a big plus and takes the worry out of high wind days especially as I go away to work for 7 days at a time ,and the little lady is left to handle the windmills as was the case with the 50klm+ winds last week when the Ax Fx had to be shut down . It was a nerve racking experience as the shut down had not been trialed in such strong wind and I had only just put it up and had to go back to work...It shut down..Phew!! and she was happy  ..Phew!!!
The jury is still out if the Ax Fx is being out performed as all the data is yet to be fully digested. To get a real indication I probably need to put the Ax into the lathe and test it there , but there has been a growing list of other jobs over the last few months. My main concern next is to re-design the tail , longer and to double the surface area and keep the weight the same . I am loosing so much power from the blades not being square to the low to medium wind , this could be one of the draw backs with such a wide cord at the tip as it exerts a lot more thrust through the offset in these conditions . I would guess at a 20 to 30% loss and it's really bugging me hence the streamers all over the place in the photos....Phill PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Hey Phill, just checking, how many and what size rivets did you use per blade. I want to set a "minium recommended" rivet size and count to keep the PVC blades on the tube. Its obviously held up in your situation, so I think 1 or 2 more rivets per blade will be a good base line. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Glenn , the rivets are 3/16 and there are 3 front and back , also they are offset 20mm from each side . The movement was definatly with the force over 700Rpm as they had hit arround 650 on another occasion with no movement . 1 or 2 more would have to be good for 1000+, but I would not like to standing to close wathcing that  PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
Great job to all parties involved. Fantastic design and machine work on the AxFx. I now feel the need to get my butt in gear and finish my F&P neo mill. Jim |
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montyLalor Newbie  Joined: 17/12/2008 Location: AustraliaPosts: 21 |
This is what I'm really interested in: data from a F&P-Neo mill. I'm not in a position to be able to build a turbine yet, but I can't stop thinking about the possibility of a 1kw+ F&P driven by those 'you-beaut, no-pole-twisting-required' parallelogram neodiums that a bloke from the 'States started a thread about a while back. Mmmmm, 1kw F&P 
Luke "So are you doin' this project to make us money or cost us money?" she asks again... |
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| mrdd Newbie Joined: 21/07/2009 Location: AustraliaPosts: 5 |
I have only recently joined the forum and am dabling with 2 F&P type 4 smart drives joined together and overdriven in a vawt (48Volt)and would like to try a axial flux to do some back to back comparisons. I am probably treading on old ground here but could someone suggest where i will find some complete easy to understand instructions to make one. I am more mechanically minded than electrically but have a friend who can explain the finer points to me. Thanks for you time. |
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