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Hornet
By Arno, Section Homebrewed Electricity Posted on Wed Dec 10th, 2003 at 08:34:09 PM MST
Jerry's comments on the Hornet being noisy and not putting out in low winds changed my mind about buying.

At the present time I have no need to charge a battery bank and would like to go for whatever heat I could get directly. I have a nice looking Dayton PM DC motor rated HP 1/2 - RPMS 1725 - Volts 90 - Amps 5.2. With proper blades and winds in the 10-30 mph range, would it give some useful heat or just be a yard decoration? Thanks for any thoughts on this.
Arno

Hornet | 3 comments (3 topical, 0 editorial)

Re: Hornet (none / 0) (#1)
by Jerry on Wed Dec 10th, 2003 at 08:51:57 PM MST
(User Info) http://www.dplusv.com/Photo-03.html

Whoops The guys at Hornet might be mad at me. I was just relating my expirience with the genny.

As far as the output from the dc motor you've discribed. If the motor could produce as much power as it consumes it could do 468 watts. I've got a small electric heater with 2 settings 750 watts and 1500 watts. Don't feel to much heat from the 750 setting.

I suspect however the output will be a fraction of the motor power rating. You would have to spin it 1725 rpm range to get close to the face plate rating. Kinda hard to do at 10 mph. Hi speed blades might get you close at 30 mph.

I suspect this motor will make a nice 100 to 150 watt genny. Just my thoughts. Now let some one with a more knoledgable perspective take a stab at it?

JK TAS Jerry

Airheads Page

Re: Hornet (none / 0) (#3)
by Chuck on Thu Dec 11th, 2003 at 10:14:49 AM MST
(User Info) http://home.morrisonprairie.com

I have no experience with hornets, so I won't add to that discussion. I do have a fair amount of experience with DC motors as generators though, so I can muddy those waters real good.

There are two key things to look at with pm DC motors, the amperage and the speed/voltage ratings.

The amp rating is more important than folks let on. It seems to have a lot to do with the ratings of the brushes. If you push them too much beyond that, the brushes can glow red and self destruct, taking various other parts with them. This is especially true in wind applications since it's difficult to turn off/down the wind. If you push 10 amps from this (5 amp rated) unit for extended periods of time, you WILL cook the brushes and/or the windinges. You can get a way with it for short periods of time, but not extended ones.

I cooked a 13 amp rated motor with 24 hours of 10-15 amp operation with peaks to 20 and 25 amps. The brushes disintigrated, the plastic mounts for the brush holders melted and the nice coppery winding insulation turned black. The commutator survived with pitting.

The voltage/speed rating is crucial in determining whether the motor is even close to useable in a direct drive wind genny. If the voltage rating is 90v at 1750rmp, then 1750/90 = 19.4 rpm per volt and 19.4 x 12 = 233 rpm for cut-in speed on a 12 volt system. This is doable but a little high. I'd do this with a two blade rotor for high TSR. This would be worthless for a 24v system unless it had a small diameter two blade rotor in a strong wind (really fast).

Chuck(M)

[ Parent ]

Re: Hornet (none / 0) (#2)
by desertratjack on Thu Dec 11th, 2003 at 07:55:15 AM MST
(User Info)

Hornets are pretty good mills, especially at the price. BUT, a furling system or a shutoff system must be designed and built for those high winds to avoid the blade noise. Hornets turn quite easily, as well as other mills I've seen but the truth is that there is not enough output from most mills in the 10-18 mph range. Right now I have 3 mills on an ammeter (503 windseeker, 6V hornet, 12v Hornet) and the wind is around 15 mph. All together I'm getting 5-8 amps (12 vdc). When the wind hits 30 mph things get interesting. Often the 6V Hornet will exceed the output of the Windseeker 503 (rated at 500 w). This might be a total of 60-80 amps (12 V) for the three mills. I am expecting some new ammeters to place in various locations to get a better handle on each mills performance (and calibrate my old ammeter) but I think the main ammeter on the system is pretty good. The conclusion should be that all windmills are over-rated. I figure the Hornets at 400-450 watts (12V). The Windseeker 502 at 350 watts, The Windseeker 503 at 400 watts and that is at around 35 mph.

Hornet | 3 comments (3 topical, 0 editorial)

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