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mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 11:14pm 26 Apr 2011
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"Did I say that right"??? Because I don't comprehind all that I wrote in the last post.
I still have'nt found the explanation for the "forward thrust" created by the wing. I know it happens because I've seen it happen in my wind tunnel. But I'm at a loss to figure out why.
I know that the lift and drag angles during level steady flight average themselves out at approx. a 45* angle above and rearward of the wing, and that the averaged force, or angle rotates or moves forward during an angled decent with less power...but thats about where it ends as far as understanding whats happening.
Can someone help me understand this? (sometimes I need to be hit on the head with a baseball batt) .....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 11:51pm 26 Apr 2011
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Last thing,
Make you'r self a good set of templets/patterns, and keep theses because you may be building a replacement wind sometime in the future.
Master pattern...used to make all other patterns, and usually has important info, measurements/angles ect.
...Calipers, I have one I made and use it as I form the profile of the leading edge.
...and your going to want to save that wing jigg too, so find some place to store all this.
Thats the basics of makeing you'r wing, first full set for me...next time I'll know what I'm doing...sorta anyway.
.....Mac46I'm just a farmer
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 01:23am 27 Apr 2011
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Mac46
This is just a guess, but I'm betting the forward motion of the blade cutting across the wind's pathway creates what is termed in flying and sailing "apparent wind". This is extra wind caused by a wing or sail's forward momentum, which passes it through the fluid flow of air faster than if it were stuck in one place.
I know in sailing, apparent wind can cause the boat to go much faster than the wind. This can be realized in a "reach" (wind off one's stern quarter; either side) as opposed to sailing "before the wind", which means the wind is at your stern and just pushes you along through the water.
Of course, with a boat, there is a maximum "hull speed" and no matter how much power you put on the hull, it will go only that fast. I don't know if a wing has any similar (hull speed) restrictions, but it may.
Maybe that's it and maybe not. Like I said, it's just my hunch.
There is a member named Carl (I think) who lives in the USA in Illinois (again I think) who is an engineer and works on the real thing (commercial wind turbines), who might be better-able to answer your questions. Maybe he'll see this and reply.
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:12am 27 Apr 2011
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Macgyver,
Thank you for you'r helpful reply. I was wondering if the weight transfer had something to do with it also. I knew about "tacking the wind" with sail boats, and maybe thats all there is to it, just seems like there should be something else involved with this. I'm real good at makeing a problem alot harder than it is sometimes.
Also, wings do have a point of resistance, like the boat hull. I remember reading that some where. Seems like the renolds number changed the faster it went or something, more reading to do on that one also. Interesting, very interesting.
Thank you again, I appreciate you'r help.
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:28am 27 Apr 2011
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Ok I think I've finely got my head around it. The air in a straight plain will try to continue in that straight path, and when a "air foil" intersects that flat plain of air at a angle, the air has a pushing force on that angle. Something like holding a flat sheet of plywood angled into the wind, it'll nearly knock it out of you'r hands. Thrust is down wind and also at a right angle to the direction of the plywood. Hey, that must be it, kind of like vectored thrust. Mac, I think you said it in alot less words....thumbs up, thanks.
.....Mac46I'm just a farmer
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 03:35am 27 Apr 2011
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[Quote=MacGyver]
There is a member named Carl (I think) who lives in the USA in Illinois (again I think) who is an engineer and works on the real thing (commercial wind turbines), who might be better-able to answer your questions
CarlJ is the "Carl" I was thinking of when I said Carl, but who I was referring to here is Perry.
Thought I'd better correct that before it slipped away again. The older I get, the more slippery my memory becomes. It's all still intact; it slides around a bit more than it used to is all. Maybe that's what happens when you work with Teflon a lot, eh?
. . . . . Mac
Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 08:01pm 27 Apr 2011
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McGyver,
Thanks for that...and thanks for the lead on "apparent wind", I've been reading some on it, very interesting.
I don't work with teflon and I'm haveing the same problems, must be something else.
Cold and wet again today, I still have that last wing to paint, been working on brackets and mounting plates. Illinois is the next state east of me, CarlJ and I are almost neighbors. I'm looking forward to speaking with him.
.....Mac46I'm just a farmer
Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1344
Posted: 07:30am 28 Apr 2011
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Just wait for that next tornado and Ya might be even closer........
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 11:04am 28 Apr 2011
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Georga, Mississippi, and other areas were devistated by tornado's last night...over 170 people were killed in the storms. Don't know how many others were injured, but it was probably several. If you've seen on close up like I have you would be astonished by its might and furry.
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 01:23am 30 Apr 2011
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I had just enough fair weather today to paint the third wing, another storm rolling is as I speak.
You can see the air blower to the left of the picture...used it to draw air through the small wind tunnel. Use it to filter the air in the shop now, just pop on a furnace filter, works pretty good as long as I place it within 6 feet of where I'm sanding. (3-speed). I use the pleated 4 micron filters. Came off an old, large gas furnace, built the box out of left overs. Price was right, free.
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:30am 01 May 2011
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"Mr. Murphy", was working in the shop with me all day today...ever have a day like this? I've had to redo some mounting plates, redezine is more like it, so that I have equal spaceing for balanceing and stress loading. I need to do final balanceing, and get a "total weight" balance of all three wings yet.
I'm ready to trial fit the first wing on the rotor assembly. If Mr. Murphy leaves me be for a day that is, and I have some calm winds.
.....Mac46I'm just a farmer
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 05:50am 01 May 2011
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mac46
I've found that Mr. Murphy and Mr. Happy have a lot in common!
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:18am 02 May 2011
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I thought I'd share this picture with you. I'm getting "the touch" back, been a few years since I've done any painting like this. This wing is the best yet, makes the first one look sick.
When ever you spray automotive paint products always have and wear an approved respirator with the correct filters. You don't want this stuff inside you'r lungs.
.....Mac46I'm just a farmer
Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206
Posted: 01:23pm 03 May 2011
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Hi mac46
I like your build, it is about the size needed to produce some serious power. The small VAWT I built has the wings made of spruce balsa and hardwood all glued together with epoxy which are very light they have been up in the air for about 6 months in some very strong winds and havnt shown any signs of deteriation. I think that with a VAHT keeping the weight down is where you gain the strenth. When balancing mine I just weighed each blade and added weight as needed before mounting them and i dont have any trouble with vibration.
Your VAWT is about the size i would like to have mounted on my shed roof one day with the shaft coming down through the roof to the centre of my work bench, that I beleive is the advantage of a VAHT.
Well done Dean.
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 07:31pm 03 May 2011
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Air Bender,
Thank you for you'r interest, and comments in my project. I have been reveiwing you project with interest as well. Nothing like hands on expereiance to put a few new wrinkles in you'r brain, and on you'e forehead. They say the forces and stresses on a flight surfice increase exponentialy with the sq. ft. and with the sq. of wind speed...add "G forces", any out of balance, structural flex, ect. and things can get ugly fast. I'm going to keep this machine stopped and bolted down during strong storms.
I'm working on mounting brackets at the moment, that and everything else associated with life, been sidetracked off the project by things lately.
When balanceing my wings, I have them weighted to center gravity naturally at 8*, and balanced within 1 oz. tip to tip, and also balanced within 1 oz. between all three wings on total weight. I have'nt had the opportunity to test mount the first wing yet, still waiting for "calm wind".
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:55am 04 May 2011
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Here is a picture of the blades after tip to tip balanceing, I was referanceing this in the last post. Fiberglass and paint added more weight than I thought.
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 11:17am 05 May 2011
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Although I did weigh each wing with a digital platform scale, I also double checked their relitive weights by putting them on a balance beam. Incredibly, you can see the differance by adding or removeing a single 5/16ths. flat washer. Final balanceing is complete, with a weight of 53.4 pounds each.
Fiberglassing and paint added approx. 15 pounds to each wing...thats more than I thought it would, but still within reason.
.....Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 01:14am 07 May 2011
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I had calm wind today, As you can see, I have the baldes on. I think I'll take a day off to recouperate.
.....Mac46I'm just a farmer
Bluegryphon Newbie Joined: 03/05/2011 Location: United StatesPosts: 2
Posted: 05:37pm 07 May 2011
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Hi Mac46
I am glad to see that you have installed the blades. You have put a lot of work into the project. Now it is time to wait for the wind and collect some data. Great job!!!
Scott
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 11:59am 08 May 2011
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Hello everyone,
In this picture you can see that I used my old truck as a elevated platform to work off of. This worked real well, a few 2x12 planks with a sheet of plywood made a good solid base to set my step ladder. I threw a rope up over the top frame and hoisted each wing up in place. "Ever have a situation where you need to be in two places at once?" Things were alittle tricky at times, especially when a gust of wind came up. All went according to the plan, (x3). Plan you'r work, - work you'r plan.
The wings are tied off and stationary at this time as I have several things to check out with the entire machine. It may be a few days before I allow it to run free. It is pulling at the teathers wanting to go.
.....Mac46I'm just a farmer
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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