Author Topic: Stupid things we (ok I ) do  (Read 14134 times)

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Offline Wolvenar

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Re: Stupid things we (ok I ) do
« Reply #15 on: February 21, 2012, 05:19:46 pm »
@m12ax7
Should we be looking for a body then, or the money?
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline oztules

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Re: Stupid things we (ok I ) do
« Reply #16 on: February 21, 2012, 05:21:14 pm »
Mark..... which was.......





ever talking about water wheels....


or was it something else?



..............oztules
Flinders Island...... Australia

Offline m12ax7

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Re: Stupid things we (ok I ) do
« Reply #17 on: February 21, 2012, 05:33:17 pm »
@m12ax7
Should we be looking for a body then, or the money?

There are NO videos or pictures (or living witnesses),  so I KNOW NOTHING!

Offline m12ax7

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Re: Stupid things we (ok I ) do
« Reply #18 on: February 21, 2012, 05:36:26 pm »
Mark..... which was.......





ever talking about water wheels....


or was it something else?



..............oztules

Well..  I didn't think the waterwheel idea is/was all that stupid, ambitious maybe....  but not stupid.   

and the other...  mum's the word!

Offline rossw

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Re: Stupid things we (ok I ) do
« Reply #19 on: February 21, 2012, 07:10:34 pm »
Far from the most stupid thing I've done - merely "one of the stupid things I've done recently"...

Had been balancing and painting my old 2.8m (10') prop. It was outside, and was just on a fairly flimsy, lightweight support to allow me to turn it freely to balance, and turn while painting...



Just a very mild breeze - barely enough to blow the paint fumes. So I'd taken off the stay so I could turn the blades to make it easier to paint.

The breeze picked up a bit, and before long it was a moderate breeze, probably 10mph or so. I thought I'd just let it turn a couple of times and see how it looked.

I didn't expect it to spin up anywhere NEAR as quickly as it did. On needle-rollers it was very free... and the blades are solid fibreglass - several kilograms each. In seconds it was far too fast to stop. It was such a flimsy mounting I didn't dare risk trying to turn it out of the wind (gyroscopic forces would likely have just broken the pin off).

Blind panic set in, I lost skin and got quite bruised, but brought it (just!) back under control by trying to grab hold of the blades back at the root and slowing it down fractionally, and moving slowly out along the blades until I could get it under control.

Never again. Nup, no way.

Offline birdhouse

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Re: Stupid things we (ok I ) do
« Reply #20 on: February 21, 2012, 07:43:07 pm »
i've never spun up blades in the "hand held position", but i did have an interesting experience not to long ago. 

i decided to work on a junction box while it was still hot.  five wires in, five wires out.  AC hot and neutral, DC + and - and a ground.  somehow i managed to shock myself with the DC - and the AC hot.  worst part is it was in one hand, and out the other.  it really jolted me, and i shock my self often at work.  it took a good half hour before i started to feel normalish again.

lesson learned!

adam

Offline m12ax7

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Re: Stupid things we (ok I ) do
« Reply #21 on: February 21, 2012, 07:47:34 pm »
Okay,  I'll admit to using a putty knife to pry out a fuse out of a 3 phase fuse/disconnect switch (440v).   It was for loading dock door,  door fully up and there was a raging blizzard outside.    The arc flash blinded me for about a half hour, in which time I stumbled around (a large furniture factory and I was the only one there, IN THE DARK, about 1 am) thru two buildings to locate the tools needed to remove the master link from the drive chain.   Had to balance the ladder at the edge of the loading dock (about a 5 foot drop) while the blizzard blasted into me.   The temp out side was about 15 and the humidity INSIDE the building was held close to 70%,  so what snow didn't cover me was made up by the buildings humidity turning into snow/ice.

And yes,  I had the time to blindly grope my way to find the needle nose/screwdriver BUT NOT THE TIME TO GET A FUSE PULLER.

I was probably 17 (still in high school),  my only excuse.
At least there were NO witnesses! 
And that's what I'm willing to admit to!

Offline Bryan1

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Re: Stupid things we (ok I ) do
« Reply #22 on: February 22, 2012, 03:40:39 am »
Well a few years ago a mate asked me test out some of his curved plywood prop setups, they were setup on 3/4 thin walled pipe and a couple of flimsy pipe clamps onto the blades. The blade diameter was 3 metres and 4 blades, for a few weeks they did a good job with a F&P washing machine motor as the genny then one night a gale came thru and the missus said to go look at the wind genny as it is sounding pretty loud. Anyway 1/2 way up the shed the blades decided to let go bigtime and one went flying straight past me landing down the hill about 50 metres away from the tower. That was it for me I went back into the house and said I aint going out there until morning to pickup the pieces. The wind was that strong it bent the 2" water pipe above the guys to a 45 degree angle and the blades must of hit the tower. I did find the pieces of 3 blades but that 4th blade was no where to be found. About 4 months later my son brought me the blade and said he found close by the shearing shed which is close to 150 metres away from the tower. Now the house is inbetween the shed and shearing shed so I was damm lucky those flying blades didnt take out my solar array.

Well it just goes to show if a guy asks you to test out a set of blades beware and make sure you ask why aint YOU testing them.

Cheers Bryan

Offline oztules

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Re: Stupid things we (ok I ) do
« Reply #23 on: February 22, 2012, 05:40:26 am »
See... that why you make wooden ones ( just don't use knotty pine like I did... live in fear)


.....oztules
Flinders Island...... Australia

Offline ghurd

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Re: Stupid things we (ok I ) do
« Reply #24 on: February 22, 2012, 07:09:28 pm »
For "Off Grid"...

There was a factory made chinees CFL looking lantern.  Users told me it was nice.
Step 1.  Do something about the 8(?) D cells.
Step 2.  Design, build, install, Dremmel tool, etc, the thing.
Step 3.  Try it with 36" test leads to a 7AH 12V SLA, which it was modified to hold.

Click the On switch.

Magic Smoke.
Not the regular kind of Magic Smoke.
This was the Extra Super Magical Smoke kind of Magic Smoke.
I am talking about LOTS of smoke coming from inside a screwed together assembly.
So, naturally, gotta get to where that Magic Smoke is originating from.
Grab the screwdriver.
Interchangeable bits screwdriver, with the #2 Phillips installed.
OK, that does not fit in the deep #1 Phillips hole where the screw is.
Where is the #1 Phillips tip?
I have no idea.
Just had it a second a ago.
After 5 seconds?  10 seconds?  Whatever.
The smoke is getting thick.
No #1 Phillips bit anywhere to be found....
Pretty sure this silly thing is gonna burn my house down.

Wholley Crap!  What do I do now?  Flee for my life?  Abandon my home to the eminent catastrophic flames?  Grab the family photos on my way out?

I reach down... and unclip a wire from the 7AH battery.
Problem solved.
G-

Offline philb

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Re: Stupid things we (ok I ) do
« Reply #25 on: February 22, 2012, 08:14:01 pm »
In the 1980's, Mother Earth News "Book of Home Made Power" had a picture of a man that had just carved a 2x4 prop. He was holding it into the wind to demonstrate how simple it is to build a wind turbine to produce electricity.

I have to wonder how many folks here saw that same picture?

That photo came to mind just as I finished my first 4 foot diameter prop. That was a neat experience while the prop was spinning up. Then I wondered, who had whom? I stood there for what seemed like two birthdays until I could turn it out of the wind. I had a nice shiny screwdriver afterwards, new knowledge and nothing bruised or skinned. My lucky day!

Could the prop spooling up in your hands have caused this insane addiction to wind mills?  ::)

Offline oztules

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Re: Stupid things we (ok I ) do
« Reply #26 on: February 22, 2012, 10:10:58 pm »
"
Could the prop spooling up in your hands have caused this insane addiction to wind mills?"



I'm sure your right Philb..... certainly burns it's antics into your mind.


..............oztules
Flinders Island...... Australia

Offline ChrisOlson

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Re: Stupid things we (ok I ) do
« Reply #27 on: February 22, 2012, 11:03:56 pm »
As the wind increases past a certain point we need to add load... and lots of it. squared function against a cubed function on a linear rpm.

Oz, that's a good description of the problem trying to control turbines with resistive loads.  It's also what I've found out playing with my voltage clipper on my Classic controller.  I already burnt one clipper to a crisp and had to regroup and re-think how to do it.  Using a really big load with PWM is the only way I've gotten it to work.

Once you get a turbine into over-speed they refuse to furl for some reason.  Even making well over "rated" power, they refuse to furl.  Not exactly sure what causes that.  But my little 3.2 meter will furl fine at 30 mph if I got it lugged down 450 rpm.  Let it run over 500 rpm and it don't even attempt to furl even at 45 mph putting out over 4 kW.

It has something to do with this windseeking thing that Flux talks about.  I never believed in it.  Flux always told me he had a turbine once that the tail busted off from.  He witnessed that turbine in overs-speed, with no tail on it, hang dead into the wind and just scream.  Since I've now seen the same thing, I believe in it.  But what causes it leaves me at a loss.
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Chris

Offline ksouers

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Re: Stupid things we (ok I ) do
« Reply #28 on: February 22, 2012, 11:23:05 pm »
It has something to do with this windseeking thing that Flux talks about.  I never believed in it.  Flux always told me he had a turbine once that the tail busted off from.  He witnessed that turbine in overs-speed, with no tail on it, hang dead into the wind and just scream.  Since I've now seen the same thing, I believe in it.  But what causes it leaves me at a loss.
--
Chris

If I had to guess I'd say it's gyroscopic forces. 20+ pounds of wood and metal spinning at 1000 RPM or more is a whole boatload of kinetic energy. The rotor disk has more energy keeping it stable than the amount of energy in the wind trying to push it off axis. Trying to furl just by pushing it off it's axis isn't going to work very well, you'll need some sort of cyclic control on the blades similar to a helicopter rotor, using it's own energy against itself.

Kevin
As far from the city as I can get but still keep my job.

Offline ksouers

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Re: Stupid things we (ok I ) do
« Reply #29 on: February 22, 2012, 11:51:57 pm »
Another posibility:
3.2 meter rotor @ 2000 RPM is a little over 1200 FPS tip speed, Mach 1 is 1100 FPS. Weird things happen with air at transonic speeds. Subsonic airfoils don't behave normally, something called control reversal is a real problem. Chuck Yeager lost elevator control at near Mach, the airplane had a "full flying tail" meaning pitch trim moved the entire horizontal stabilizer to make trim adjustments. The only way he got it under control was to use trim, not the normal elevator control. Modern supersonic aircraft still use this same control method of moving the entire tail.

Perhaps something similar is happening on the turbine at very high speeds, instead of drag pushing the rotor off axis the blade are producing lift towards the wind instead of the normal away from wind direction. Essentially it's in equilibrium pulling the turbine forward as much as the wind is trying to push it back.

Just the crazy random ideas going through my mind as I'm half asleep...


Kevin
As far from the city as I can get but still keep my job.