(Photo) Foam & Epoxy nose cone for my 12'

[Dave B]

I figured it wasn't quite finished without a nose job. It's made of 5 layers of high density foam insulation disks glued together on a 16" x 3/4 " plywood disk. A 3/8" bolt was screwed into a "T" nut in the center before gluing the foam on and then was chucked into my cordless drill. Took a rasp to it at slow speed to rough the shape and then smoothed it by sanding it the same way. About 3 coats of Wests System Epoxy again sanded the same way between coats and finally a few coats of gloss white enamel. It's very light and lag bolted through the back side of the front hub plate with 2 stainless bolts between each blade. A bead of white silicon caulk along the edge when I bolted it on seals it up. Might need just a slight tweeking of balancing but it all seems very close to what it was and runs very straight and true. It was a fun project and may just help the performance a bit besides. I can't remember who else out there laid the ground work for me on this but thank you, I just needed to get at it. Dave B.

[windstuffnow]

   Ain't that peerrrty!  I always though about putting one on my turbines... thats about as far as I made it.    I wonder if it adds anything but beauty?

Have Fun

Windstuff Ed

[Treehouse]

I can't remember where I read this but someone did a study on it and found that it ever so slightly hurt the performance, something about the added drag of the nose cone sping caused the rpm to drop. Again if I remember it was a very small loss of power like 1/4 of a watt. The where going to test a solid nose cone next(Stays stationary of the blades) But personaly I think it looks great!! Keep up the great work..

[John II]

Wow... is that sharp or what ! That really dresses it up Dave B. Makes it look like a factory job.

I'm guessing that it'll definately not hurt the performance either.

John II (S.W.Missouri )

[nothing to lose]

I'm not entirely sure but I think I read where they actually are supposed to help a bit with performance, not hurt it.

 Something about flowing the air/wind nicley to the root of the blade that would otherwise just hit the hub like a brick wall.

It would figure too of course that the air/wind that would hit the hub has to go somewhere somehow one way or another. If it just hit a solid flat object like the hub I think it would just spread out any old way it could and be turbulent right there near the hub also. Flowing it nicely like that with a tappered hub might prevent the turbulance at the roots or at least lessen it.

Let us know if it seems to make a difference either way, and it sure does look nice.

Great job, looks better than many store bought items do. The whole mill and tower look nice too.

[Shadow]

 That looks very nice!I like that idea and I too think it would help deflect the wind off towards the root. You see them on all the big turbines in our area.I mocked up one of the wifes stainless steel bowls,(until I got caught), but decided that would be one of those do it later projects. I think I'll get back at it now.

[Dave B]

Thanks guys for the compliments. I'm very satisfied with the results and for what little time it took compared to the hours I have into those blades it was very much worth it. In theory I believe it should be slightly more efficient and I think I am seeing this at start up and in low winds. As usual, whenever you try something new the wind seems to stop blowing so nothing over 10 mph since. I can't wait to see it running at 300-400 rpm in those 25-30 mph winds just before it starts to furl. I've calculated 420 rpm from the measured AC frequency unloaded in I'm guessing 30+ mph gusts. I just received today my Kestrel hand held annemometer so between that and my logging software I'll have plenty of fun with the specs. I really can't wait to get this up in the clean air hopefully this Spring if the weather ever breaks. Thanks again,  Dave B.

[Ziggy]

According to this article http://www.hydrogenappliances.com/conecon.html, they do claim that they hurt performance ever so slightly. Then again look closely at the nose cone they have pictured. It looks to me as if it is not completely round or a cone, which could have caused some turbulence. The cone you built looks awesome at any rate.

[Ziggy]

I don't know why that link don't work, but try this one and go down to the bottom of the page and look for the cone controversey article. http://www.hydrogenappliances.com/bladekits.html

[rotornuts]

Hey dave the cone looks good and appropriate. The great cone controversy where the cone caused deminished performance likely has everything to do with the fact that the cone is freakishly large for the rotor it's on and nothing to do with the fact that it's a cone. I suspect the massive cone on that thing is wreaking havoc with the airflow at the root of the blades considering no modifications were made to the blade to accept the additional and accelerated air. I would also challenge the wisdom of running the cone against the root of a blade with such a strong taper.

[PHinker]

She's a beauty Dave!  Very nice, finished look.

[Ungrounded Lightning Rod]

[study found] it ever so slightly hurt the performance, something about the added drag of the nose cone sping caused the rpm to drop.

If I had a wind tunnel I'd be tempted to try making one with smooth spiral indentations, matched to the speed of the wind at various radii, pulling a thrust from the wind while directing it into an appropriate region of the blade.  Probably onto the downwind surface just past the leading edge for added lift, but I bet different shapes would work well dumping it into different regions (the gap, onto the upwind surface).

Seems to me that if you shape it right you should be able to pull power from the slug of wind that would otherwise hit the hub, rather than just deflecting it around the nacelle.

[wooferhound]

The cone is supposed to redirect the air at the hub so it goes through the blades faster. So the wind speed at the inside position of the prop would be faster than at any other point on the prop. It seems that the hub position of the prop would need to be designed for that extra wind speed.

Another thing that I'm thinking is that you really don't need a cone, the wind will naturally redirect itself around the hub and through the blades.

Still looks great there Dave B !

[Dave B]

I think to be more ideal the shape should be more rounded near the nose and then straightening more perpendicular to the blades at the root. This would create more of an airfoil around the cone rather than just deflecting. Also, in my case if the root taper of the blades were closer to the cone I think more of the deflected wind would be directed over the steep angle and help start up even more in lower winds. My first goal was to make it look finished and in proportion, I'm happy with that. I think very light weight high speed blades (as shown on the link previous) would definetly be more likely to be loaded down by a cone with large area and or weight out of proportion to the blades. The argument will go on I'm sure as to improved performance or not but to be fair all variables for each mill and hub design should be considered in each case. From a marketing standpoint if the engineers get the design of a nose cone close to or same as the performance without it and it looks decent you can bet they'll leave it on, if they don't their competitors will. Ever known people to buy speakers that "look" good no matter that their ears or specs. may tell them otherwise ? My rotor still starts with a few seconds of 5 mph wind, it will be interesting one way or the other if I can notice a difference in performance up to furling winds of 30 mph. Like driving a clean car, sure seems to go better and the neighbors may appreciate it a little more besides. Thanks for all the comments and feedback, interesting stuff.  Dave B.  

[richhagen]

I agree.  In laminar flow, there is a graduation in the speed of the fluid as you move away from the surface.  In looking at the cone they display, Its outer perimeter is at or near the root of the blades.  If this causes a reduction in airspeed on part of the root of the blade it would make startup more difficult as applied force would be reduced.  I would think that a properly designed cone would improve performance, not hurt it.  Rich Hagen

[newguy]

well i found this link a while back when i had a question about it

http://earthsci.org/energy/wind/wind.html#The%20Purpose%20of%20Windmill%20Shrouds

but i think a well designed blade to shroud will increase performance

i think the shroud dave b is awesome and looks really cool

i dont know much but yup