Fly weight governer on 20 foot machine

[fabricator]

Well contact Dave, that's the simple answer, and as for constant profile and pitch, these blades are torque monsters, if you put em on a turbine you better have a good way to shut it down, or dump a lot of power, the Dans put a set on one of their 17 foot machines and they smoked it.

Would not argue with the torque characteristic but I question if that`s they way to get best performance from a given blade size as power output is the product of torque and RPMs.  These `torque monsters` don`t tend to turn very fast so the torque & RPM product tends to be smaller than for a more aerodynamic, faster rotating blade i.e. one with varying pitch and profile. 

Higher RPMs also allow for a physically smaller alternator or, less need for a gear-up.  I guess though advantages of constant pitch and profile would include some measure of self-RPM limiting (as the blades operate somewhat in drag mode) and maybe cheaper to manufacture (no compound curves). Also easier to brake I suspect.

I build geared machines, lower rpms with a geared up machine allow for a physically smaller alternator, that will see rpms a direct drive might see in a tornado just before it disintegrates.

[cdog]

I was in fact talking about a 25' geared up machine....

[NoSmoke]

Sounds like a good blade for gearing up?
This is why they have caught my eye.....id like to have 25' diameter though....

Yes they are, a 12 foot geared turbine will likely out perform a 25 foot direct drive by quite a bit and be a lot less headache as far as support structure goes, just check what Chris Olson is doing.
He has 10 foot machines that out perform his Jacobs.

Sorry, I have to disagree with that - performance (if by that we mean power output), all else being equal, is directly related to swept area.  A 25 footer has more than four times the area of a 12 footer and, it would have to be a poorly designed turbine indeed to be outperformed by the 12 foot.  Gearing up itself has little to do with it - it does allow for a smaller alternator (physical size, not output) but that`s about it i.e. a given turbine will perform sorta the same with a small geared up alternator vs a direct drive properly matched to the turbine (actually the direct drive performs better due to absence of gear-up losses).

[Royalwdg]

I here ya NoSmoke,  Wattage is wattage.  gear it up to get the voltage with higher rpm.  Depends on your choice of alternator.  Chris Olson has been all over this.  You need to know what your choice of alternator needs first then dicide if you need gearing up or direct .  Blades are going to function in specific rpm range. All this to design your whole package.   Dave M

[NoSmoke]

I here ya NoSmoke,  Wattage is wattage.  gear it up to get the voltage with higher rpm.  Depends on your choice of alternator.  Chris Olson has been all over this.  You need to know what your choice of alternator needs first then dicide if you need gearing up or direct .  Blades are going to function in specific rpm range. All this to design your whole package.   Dave M

Yes, what we are doing is matching the alternator to the blades.  The alternator firstly has to be able to handle the amount of energy input from the blades and secondly, be run at the correct RPM to convert that blade energy input to Watts.  If for example, the blades want to turn at 300 RPM max and so does the alternator to produce full output, then a direct drive is fine.  OTOH, if the alternator needs to spin at 600 RPM to produce the same output, then a 2 to 1 gear-up is called for, and so on. 

In my particular case, my 12 footer spins at 300 RPM max (governed by pitch control) and my motor conversion alternator needs about 850 RPM to produce 120VAC and full Wattage, so my gear-up (roller chain) is 2.8 to 1.

Direct drive has the advantage of not needing roller chains or gears but is practical up to only a certain point.  With v large turbines, the blade RPM is so low that an appropriate direct drive alternator would be prohibitively large, heavy and expensive.  IIRC the large commercial units have gear boxes at a 70 to 1 ratio or thereabouts.

[Royalwdg]

Don't dismiss the 3 phase motor conversions.  Sure the output is about 1/3 the rating of the original motor tag but when times get tough, like now and only getting worse,  motor conversions may be the only viable way of creating you own power.  More rpm will be required along with gear boxes.  I don't see anything simpler than Chris Olson's transmission.  We all have to keep open minds and be versatile.  This is the greatest venue for this kind of knowlege.  Dave Moller

[NoSmoke]

You should be able to get way more than one third face plate rating out of a motor conversion, in fact you should get face plate or more if you spin`em fast enough, even with ferrite magnets.  And with neos you can get by with maybe one half the max amount you could otherwise cram in if you use a suitable gear up (a benefit now that the price of neos has increased).

[bvan1941]

I think this discussion has lost sight of the many variables in deciding if a particular airfoil and if a transmissions will provide a useful output. Chris has cited many of these variables in discussing the operational merits of his turbines.

One major point he makes, is the extreme power of the GOE-222 blades along with the inability to control the power these blades make (in his area of mid to high winds and the air density combined) in high winds. If I used this type of airfoil, I would try using a much smaller blade length to offset the extreme torque generating capabilities.
By the way, Chris states transmission losses are minimal overall.

My two cents,
Bill

[fabricator]

I have a 4:1 machine on the stand right now, it takes three ounces on an arm one foot long to spin it, so yeah, minimal about covers that.

[cdog]

Anybody using gears or is chain and sprockets the common route?

[fabricator]

Chain and sprockets, gears are a whole nuther animal, with chain you have some leeway, if your gear alignment is not PERFECT they will be shavings in the bottom of the case in short order.

[Royalwdg]

bvan1941,  There is not a problem controlling GOE222 blades.  One of the ways is this flyweight governor.  The tail wagger.  Wincharger used to use a flyweight controlled air buffing arrangement.  Any blade choice will run away if you don't furl in some way.  Yes the 222 has a lot of torque so you can't just hit the shorting switch at medium to high speed. It will power right through.  And some one else mentioned it was a lower speed blade.  My 20 footer has seen 300 RPM.  Jarrod has checked his shorts a few times with similar experiences.  A 222 12 foot machine can run up to 500.  I cutting a smaller profile now that will run 8' dia. two blade up to 1000 RPM.     Dave M

[cdog]

I sent you a message on your site......
Have you ever.....or can you make a blade longer than 10'??

[ChrisOlson]

One major point he makes, is the extreme power of the GOE-222 blades along with the inability to control the power these blades make (in his area of mid to high winds and the air density combined) in high winds.

Bill, the GOE222 does not stall easily.  It is a very high-lift profile and operates very well under a wide range of angle of attack.  But that does not mean they are slow.  It's my opinion that they are very well suited to slow turning geared turbines.  But they can run too.  I ran a 4 meter (13.1 foot) diameter two blade GOE222 machine for awhile that ran at 500 rpm.  I finally took it down when it broke the tower mast after two days of 40-50 mph wind, putting out 3-3.5 kW.

Since the GOE222 does not stall very easily, once you get them lit at 30-40 mph wind you can't stop them.  If you try brakes or shorting the generator they will just lug down and pull harder.  You need to design the package around the blades accordingly.

You cannot get the Cp from the GOE222 that you can get from the very high speed S809's that I'm using on my latest 150 volt turbines.  The S809's run up to 47% efficient while the GOE222's top out at about 35%.  But the GOE222 will run well at a MUCH wider TSR range than the S809's.  You can have set of S809's spinning at 600 rpm and TSR 7.5, lug them down to TSR 6 and they just give up and quit.  At TSR 7.5 the GOE222's are very inefficient, and at TSR 6 are just starting to put serious twist to the shaft.

It takes a well-designed "package" for the GOE222 that is designed to take advantage of the blades' operating characteristics.
--
Chris

[bvan1941]

Gents,
Let me state that I believe the GEO-222 profile DaveM produces is an outstanding blade !! I want a set of Dave's blades in the worst way for a project I've been planning for some time now.  Ideal 3 blade rotor, diameter of 6-8,' poplar 222's ! YES!

I want to utilize that extreme power(222 foil) running (hopefully) at 300RPM's, with a strong generator(4kw +) that needs 900-1300RPM's, I plan to deliver via a chain driven transmission (Like Chris's).
 
I don't have the year long steady 12-15mph wind speeds and I don't normally have to worry about 30-50 + mph winds either. The 222's wider TSR ability and strong torque under a heavy load I believe will work to my advantage where a foil with a narrower TSR range, would more likey be pulled out of its ideal powerband and fight stall conditions in lighter winds and heavy loading.

Basically, I want to use the (222) torque in driving an efficient chain driven transmission to gain generator rpm's to bring it into it's useful powerband. Blade efficiency is not necessarily my highest priority, power through torque is!
Bill

[Ungrounded Lightning Rod]

Untwisted blades can be surprisingly well powered and well behaved.  The outer half of the bade sweeps 3/4 of the available power and the ideal twist changes the chord angle by only 2:1 over that distance.  With a profile that's efficient over a range of angles of attack it's not all that much less efficient than a twisted blade.

It also has an advantage if you're trying to use the load to stall-regulate it.  When going into stall, a twisted blade reaches stall essentially simultaneously over the whole length of the blade.  With an untwisted blade the inner ends of the blades may always have been in stall, and as the RPM/wind speed ratio drops the stalled disk expands outward.

[acme12]

Hi Royalwdg
Do you have any good news about your nice turbine with pitch blade control? Any problems with pitch bearings?

I hope that's not a secret, what is the dimension of the cross section of the blade root?