Author Topic: 1280 W output !! and messed up the balance  (Read 1206 times)

0 Members and 1 Guest are viewing this topic.

jacquesm

  • Sr. Member
  • ****
  • Posts: 467
1280 W output !! and messed up the balance
« on: November 24, 2004, 09:12:01 PM »
Yesterday we flew the mill for the first time a whole day in one go.



It went pretty good, all things considered, all the major parts were still on the machine when we checked it in the morning. (read that as 'it still had three blades').



Peak power was 1280 Watts in a 24 mph wind, not great, but the windings are still in parallel because I can't trust it fully until I have seen the feathering work.



Then, after this successful run we decided to mess it all up... Temporary insanity, if it works don't fix it and all that... We took the machine down and removed all the weights, then tried a new way of balancing it from scratch, resulting in much less weight on the blades (there was some 'common' weight, and on a three blader you should never have to add weight to all three blades...).



We also improved the tracking still further, that's an ongoing process.



After that we tried flying it, but it shakes badly.



We'll be building a rig tomorrow that holds a drillpress on it's side, that will drive the machine via a belt. That way we're not depending on the weather and it will give us a possibility to run the machine at it's rated speed (with the blades 'flat') to see if the feathering works.



If it does we'll switch to high voltage, if not we'll leave it like it is until we have a fix for whatever problem might occur.



« Last Edit: November 24, 2004, 09:12:01 PM by (unknown) »

monte350c

  • Full Member
  • ***
  • Posts: 228
Re: 1280 W output !! and messed up the balance
« Reply #1 on: November 25, 2004, 04:34:50 AM »
Hi Jacques,


Congrats again on a really good looking rig. I alomst didn't write this because it might be a way off base - but here goes. I used a piece of half inch all thread for a centre pivot on a 12 square foot savonius model I built a while ago. When I went to measure it to get appropriate bearings I was very surprised about the big variations in outer thread diameter - more than 50 thou on the piece I had. Anyhow - my question is: Does the centre hub (the one with the links to the 3 weights) on the all thread on this machine rock at all on the all thread? Try holding two of the weights and push and pull the third one in the flat/pitched direction. If it can move at all it might be unloading as that blade passes the tower. A fix might be to replace the all thread with a piece of steel shaft and put bronze or other bushings inside the centre hub so it can't rock. Good luck with it, and looking forward to reading about your success as I'm sure you'll nail it!


Ted.

« Last Edit: November 25, 2004, 04:34:50 AM by monte350c »

jacquesm

  • Sr. Member
  • ****
  • Posts: 467
Re: 1280 W output !! and messed up the balance
« Reply #2 on: November 25, 2004, 06:38:36 AM »
Hi Ted,



I'd been wondering about that (I measured the allthread at some point and turned the rider to match) and yet there is a bit of play.



I never bothered to check it but we did agree that the allthread is a bit of a stopgap until we have the dimesions for proper feathering action deteremined.



The wind loading the blades is pretty symmetrical, but I can imagine that while a blade passes in front of the tower the pressure wave from the air between the two pushing the blade out of whack a bit.



This will need adressing at some point. Right now we are taking notes and figuring out everything that is 'wrong' with the design to redo the governor portion at some point. Long term allthread is not a solution, its a convenient stopgap.



« Last Edit: November 25, 2004, 06:38:36 AM by jacquesm »

picmacmillan

  • Hero Member
  • *****
  • Posts: 523
Re: 1280 W output !! and messed up the balance
« Reply #3 on: November 25, 2004, 11:29:14 AM »
hi jacquesm....nice job on your genny

how tall is your tower?....looks like

a good place for wind,....have a good

one......pickster
« Last Edit: November 25, 2004, 11:29:14 AM by picmacmillan »

jacquesm

  • Sr. Member
  • ****
  • Posts: 467
Re: 1280 W output !! and messed up the balance
« Reply #4 on: December 25, 2004, 08:31:22 AM »
The tower is 60' high, on an island in a lake (Lake Huron).
« Last Edit: December 25, 2004, 08:31:22 AM by jacquesm »