Wind turbine in high winds

kokes · May 2014

Hi,
I have observed an interesting phenomenon.

I invented, calculated, described and built my own turbine. The time came to test it out. Since I have access to no speciality equipment and I run on a very tight budget I decided I would start with no bearings and no other unnecessary equipment. Instead I attached my turbine to the tip of an arrow, removed the now unnecessary fletchings, and shot it.

With weak bow at half draw the arrow flew excellently. It stabilized itself well, it started rotating as soon as it left the bow, the ballistic curve was great, the rotation was ultra fast (lift type turbine). Compared to standared arrow the range was increased, and so was the precision, especially in high side winds.

At full draw however strange thing happend. The arrow wouldn't start to rotate for many meters. It would flap in the air helplessly slowing down noticably, until the arrow finally started to spin. Then and only then did it start to fly normally, not slowing down much any more and keeping the right trajectory. The arrow landed at about the same distance as its flached counterpart, but it flew sideways and inconclusively. At the beginning of its flight it looked like the turbine couldn't catch air somehow. Kind of like when you pry too much gas into your car's engine and the engine doesn't start until you push your car down the hill with gear in place.

Now this puzzles me. From physics I know that arrows energy increases with square of its speed. The turbine should have started spinning much easier and faster compared to lower flight speeds. However this was not the case. The only thing I came up with so far was similarity with propeller cavitation in water. In water places are created with low pressure, and the propeller slips through. But this idea didn't get me far.

My guess is that I should make the turbine smaller as this didn't happen when I had been using heavy crossbow arrows. With ultra light lean titanium arrow for kids I ran into difficulties. Or perhaps I would have run into difficulties with heavy arrows if I had had access to a strong bow? Anyway, these are my questions:

Have you ever encountered or heard of a scenario where the energy created by a wind turbine increases up to a point with increasing wind speed, then remains flat, then decreases? Or that the turbine takes time to catch up when started too abruptly?

What should I do to increase the performance of my arrows? Make even smaller turbines (1 inch diameter right now)?
I am planning on making money on arrows to start building my large turbines, I don't want to die waiting for investors like Tesla did.

Shoud I rather use my turbine just for hydro, waves and winds instead of considering gas and steam? How do I go about that without sufficient financial backing?
After all, my turbine in river did surpass Gorlov, top of the line today, spinning at below 0.5 kmh-1...

These questions are crucial to me. Thank you for your input.

Jan Kokes

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mike95490 · May 2014

Re: Wind turbine in high winds

I'd say, at full draw, the turbine did cavitate (air flow collapsed, "wing" lost lift). But I'll bet when you go to harvest energy from it, instead of letting it "freewheel", you will find it will loose airflow and not work well. 50 MPH arrow and 15mph wind is quite different.

About the only improvement I've not seen on wind generators, is the winglets on the tips of the blade. Conventional airplane props have been optimized for many years, and only slight mods change a motor driven prop, into a generator driving airfoil.

kokes · May 2014

Re: Wind turbine in high winds

Hi Mike,

thank you for your reply. It may be cavitation. I am not sure what to do about it. My reasoning right now is that the turbine as is is too strong for the amount of kinetic energy.

On the other hand I am not too concerned about "loosing airflow" if you mean by that that the turbine won't be strong enough for the generator. I have a whole program that calculates these for me with 3D outuput for 3D printers. I can change thickness, width and profile of blades. I can make the screw more twisted. I can have any number of blades. Increasing strength is piece of cake. Making a turbine that will spin with minimum energy is my goal. That is why I practice with arrows. They have been around for thousands of years, spinning arrows for about 500 years. Noone has ever designed a turbine with so little drag that it would stabilize arrow and let it fly further than arrow with fletches at the same time. That is what I'm after and that is what I observed at low speeds.

My turbine is optimized with winglets, only they stretch to the rear of the turbine and join in a continuous loop, so they aren't distinguishable. But they are there, big time.

Oh, and the wind it spins in is around or little below 5 mph. I tested it many times, first time in my early free fall experiment. The turbine you can see there was hand made using only egg, pencil, paper, ruler, scisors and glue. I calculated the speed from a distance where it started spinning.

BB. · May 2014

Re: Wind turbine in high winds

There is a wind turbine that looks similar to your design called the "Energy Ball":

http://www.lowtechmagazine.com/2008/09/urban-windmills.html

http://home-energy.com/cms/wind-power/

-Bill

kokes · May 2014

Re: Wind turbine in high winds

BB. wrote: »

There is a wind turbine that looks similar to your design called the "Energy Ball":

Hi Bill,
yes, it looks similar. The main difference is that this design seems drag action only, while my design is mainly lift action. It combines both actually, but it is mainly lift. The turbines that are both horizontal and lift action are rare, that is why my stakes are so high. I like the note about silence, I also never heard any sound with my turbines.

BB. · May 2014

Re: Wind turbine in high winds

Jan,

I am just guessing, but it appears to be a "true" HAWT (horizontal axis wind turbine) with the axis of the blades pointing into the wind (and tail "at the rear").

I think the blades are are similar to a standard HAWT, but the blade "tips" are folded back to the "rear" of the rotor (where the bearings and tail is located).

A few decades ago, when hang gliding was becoming very popular on the West Coast of the US, the designers/manufacturers of the gliders would mount them to the back of a pickup or flat bed truck and run down a 1 mile road (parallel to the Half Moon Bay airport) to test their designs.

As long as your scale models are not too large (in the US, over 8' or ~2.4 meters can get you in trouble on public roads--You could probably do similar experiments with your design and see how it runs.

http://www.otherpower.com/bdwm53.html

You only need to get upwards of 30 MPH (~48 KM/H) to figure out the basics of your design.

-Bill

kokes · May 2014

Re: Wind turbine in high winds

Excellent suggestion, Bill. I was thinking about mounting it on a mountain bike and ride in corridors of my appartment building in order to avoid wind. But now while I have neither car nor bicycle I test by shooting.

I took advantage of my broken turbine from yesterday, ripped one blade completely off and was shooting with single blade (the pictures here mainly show 2 bladed version). The arrow flew a bit further than the fletched one, and the flight was less wobbly compared to yesterday. At half strength the arrow flew just as well as 2 bladed version, started spinning a dash later perhaps. I was surprised by lack of visible vibrations I was hoping not to see with a single blade.

Anyway, I consider it a fail. Thinner blades are now on my list to reuse my mold. It can be printed, but costs a lot. Looks like this, only it is made of two (identical) pieces. The one on video was designed to be made of hard materials, such as machined aluminium, and it couldn't be opened with casting in it were it 2 piece mold. I also made sure it can be opened along cartesian axes with no rotation so that the production can be automated easily.

kokes · May 2014

Re: Wind turbine in high winds

I was testing some more today. I may now be closer to the solution of the whole mystery. I believe that the reason for helpless flapping is due to air going around the turbine, not through. I will use pictures from my first post for illustration. On the very left there is a turbine with thick blades. On second from the right there is a similar turbine, but with slim blades. Take a close look at right bottom corner of each, that is a frontal view. There are round openings for air between the very center and the blades. The grey spots, two or three respectively. What I discovered is that these must be large enough in relation to the blade width.

Now I will give you my reasons. Take a look at the first one. That is how my last week's turbine looked like. The openings are tiny, the blades are huge. The arrow flew horribly.

Here are pictures of what I was shooting with today:
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See how I screwed up the screw? The opening is oval, despite me trying to make as large hole as possible. My mold was too large for 4 millimeter blades... Anyway, I tried my best, and it is better than what I had had before. It still flapped, but less. The arrow rotated well up to 3/4 of draw length, then it flapped, and not much. It flew further, too. I got 37% increase of distance compared to standard fletched arrow. Not even close to my record 83% increase, but still ok.

Now my main reason for thinking bigger holes would be better is my first arrow that so far seems the best I have made. It is the one from the video. It is also the only one that got shot from Olympic bow by Fred Williams. It rotated well but got destroyed upon impact. I haven't spoken to Fred since, I wanted him to shoot the thing as far as possible, not to destroy it for fun. And I feel he isn't very anxious to see me, neither. But he did shoot it and he may still posses the video I was recording. Anyway, back to the original arrow. It's diameter was more than twice of what I have now. It had inner diameter equal to the diameter of chicken egg, precisely. I glued it to an egg. The blades were 7 millimeters wide. The relative size of openings was therefore much greater. The overall shape was a bit shorter and broader than my recent pinecone shape, which may also play role. I abandoned the original shape since I thought the new sharp one would be more aerodynamic. Obviously it isn't.

BTW: See the cut on my hand? It's 3 days old. Half a year ago I was defending front mounted turbine on arrow, main reason being that rear mounted turbine would cut one's hand EXACTLY like that. I was SO right...

inetdog · May 2014

Re: Wind turbine in high winds

A fascinating discussion, although a little over my head (That was fortunate for William Tell's son).

Two things I would note (and then some more):
1. The kinetic energy of the arrow does vary as the square of the speed, but
2. The energy extracted by a wind turbine, at the optimal generator resistance for its speed, varies as the cube of the wind speed.
In your case you are not deliberately trying to extract energy from the turbine yet, so that may not be of much interest at this stage.

Also, two ways that conventional wind turbines are constructed to avoid self-destruction as the wind speed increases above their design range are to stall the blades and to furl the blades.
(The more common way than either of those is to rotate the turbine axis perpendicular to the wind.)
Both of the two methods rely on the shape of the blade or the root angle of the blade changing under centrifugal and aerodynamic stress such that they blade no longer efficiently extracts energy from the airstream. At that point, the mechanical load of the generator is able to keep the blade speed under control even at high wind speeds.

And finally, if you look at the cross section (swept area) of the turbine, a "hole" in that cross section is at most going to reduce the available energy in proportion to the decrease in swept area. I do not think that in the speed and pressure regime you are operating in you will see a greater effect than that from any hypothetical "leakage" of the airstream around the blades.

kokes · May 2014

Re: Wind turbine in high winds

Hi inetdog,
very interesting reply, thank you. I have one question as well as few answers.

inetdog wrote: »

you are not deliberately trying to extract energy from the turbine yet, so that may not be of much interest at this stage.

I agree completely. I am deliberetly trying to make a turbine that will already work, but extract minimum energy in the process. Extracting more will come next, with addition of extra blades, by "nesting" turbines with opposite spin inside each other for greater relative speed, by "chanining" multiple turbines on single axis to increase the torque.

Nesting turbines:
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Chaining turbines:
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inetdog wrote: »

Also, two ways that conventional wind turbines are constructed to avoid self-destruction as the wind speed increases above their design range....

My turbine is designed to withstand very high rpms. It arches all the way around, so in order to destroy a blade it would have to be damaged at three places simultaneously (on each side and in between).

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Despite that I did countermeasures against too high wind. My towers will be floating on water. They will consist of a large light ball (or ellipsoid or perhaps a donut) with heavy bottom. At the top of the ball there will be light construction erected with a funnel like in the picture above. Alternatively the tower could be just a flexible rod, or the funnel could hang from top, but let's stick with the original tower for now.

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The funnel will direct itself against the wind at all times authomatically, just like wind bags at airports. Should a wind too strong come, the whole tower will tilt the funnel away from wind, leaning backwards, front of the funnel getting higher than the rear. The stronger wind, the greater the tilt. The structure will need to be ballanced for the right wind speed in relation to the funnel resistance, but the results are worth it. The turbine will always work at greatest achiavable efficiency, not stopping completely. It will require no electronics. And the funnel will have a marvelous effect of increasing wind speed that passes around the turbine, as Bernoulli's equations attest. And that means much more energy to harvest (the cube of wind speed...). The openings of a funnel can be fitted with nets against eagles or fish or anything else that might otherwise get shredded. And as a bonus, the funnels are unlike turbines easy to build and dirt cheap.

(but you can't use funnels for standard wind turbine as they already are prone to explosion, and besides their blades need great diameter, unlike my blades that can simply stretch out to the back)

inetdog wrote: »

And finally, if you look at the cross section (swept area) of the turbine, a "hole" in that cross section is at most going to reduce the available energy in proportion to the decrease in swept area.

This is clear.

inetdog wrote: »

I do not think that in the speed and pressure regime you are operating in you will see a greater effect than that from any hypothetical "leakage" of the airstream around the blades.

This is not. Can you elaborate on it? Perhaps rephrase it? I appologize, it may be due to my English, it is by no means perfect.

kokes · May 2014

Re: Wind turbine in high winds

Today I was testing some more. I made a turbine that I knew was going to work. And this time it did.

The arrow surpassed the original arrow by 41% in a distance. It finally rotaded very well every time and the ballistic curve was excellent. The only drawback was that it got stuck in a canopy of a wallnut tree and I couldn't retrieve it. But I have more arrows at home, so I can build another turbine tomorrow and test some more.

My proposal about the "holes" seems to have been right. I inspected my turbine (HAWT) carefully before losing it. It's inner width was 3 times larger than the blade width. Which corresponds nicely with what I read about eggbeater turbines (VAWT), where the space between blade and axis needs to be also 3 times larger. Tommorrow I will go for a large opening combined with 4 mms blade, not 7 mms as today. I used a single blade and will continue doing so.

I have no camera and no proper bow, but I finally finished translating one book yesterday, so I got at least some money. Enough to take a bus to Sedimorky camp North of Prague, which is usually packed with turists with cameras and where they have a range of bows of variable strength they rent. The exact date will depend on weather, it was very rainy lately, not good days for shooting.

Anyway, so far I am happy with the results. It took over a year of testing, atop of many years of self study and trial-errors. I wanted to have the whole thing ready for 2016 games in Rio, and it seem like I have plenty of time to make it happen. I think a major sports event could get a lot of publicity that my turibines and wind power in general desperately need.

BB. · May 2014

Re: Wind turbine in high winds

You are probably going to have a difficult time figuring out the "best" turbine blade design using arrows.

Arrows that go the furthest would simply have the least amount of drag.

Arrows that go less far either convert energy into rotational energy of the arrow and/or simply add drag to the arrow. I don't see any way of figuring out which is which without doing something like a high speed camera to measure rotational speed and monitor the "feathers" during flight (do they "collapse" at high speed and only expand out and convert to rotational energy as the arrow slows).

Arrows fly at a lot higher speeds than a typical wind turbine operates at. And you can have significant scaling issues (differences between small model and full sized operation).

Do some research on "Reynolds Number" and such...

http://ittc.sname.org/proc6/Reynolds%20Number%20for%20Model%20Propeller%20Experiments.pdf

Modeling is a very interesting subject and has a long and productive history for Engineering. But understanding the scaling issues is critical to being able to scale up your test results.

-Bill

kokes · June 2014

Answers for Bill

Hi Bill, thank you for your input. This time you got me really busy.

BB. wrote: »

Arrows that go the furthest would simple have the least amount of drag. Arrows that go less far either convert energy into rotational energy of the arrow and/or simply add drag to the arrow.

Bull's eye. That's a exactly what I am after right now. Low drag high speed. Thus arrows.

BB. wrote: »

I don't see any way of figuring out which is which without doing something like a high speed camera to measure rotational speed and monitor the "feathers" during flight (do they "collapse" at high speed and only expand out and convert to rotational energy as the arrow slows). Arrows fly at a lot higher speeds than a typical wind turbine operates at.

I simply can't test like that, I lack the means. But I got it working regardless. Call it beginner's luck.

BB. wrote: »

And you can have significant scaling issues (differences between small model and full sized operation).... to scale up your test results.

I wasn't aware of that. But you may have noticed that I put a lot of work to the production process. I can do the turbines with no special tools or expensive materials.

The rest of this post may be boring for some of you, it doesn't deal with turbines per se.

Tests in vitro and in vivo count the same. Results are what I am after, and I got this lifetime only. So I take the fast track by actually building things. Check the list of my inventions. Only those marked with T have been tested by now. PP means patent pending, PU means published, ? means I am not sure whether they will work or not. Choose any top level one and I will publish it right here. None of the inventions use more than 1 (!) moving part, except for the one that consists of Van de Graaff generator, which uses belt, rollers, bearings and DC motor.

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I got no time to spare. My father is a university professor, I was reading on physics while my mates were reading fairy tails. What I acquired must be good enough for me. I need to get to metal processing now.

For that I need money.

So far I was a tourguide, designer, translator, interpretor, worker at bee farm, truck driver, international trader, programmer at multiple positions, aside from various office and IT jobs. I am quailified and or experienced in all of the above. I have a licence for court translator and interpretor. But I can't get a steady job. There are several reasons for it, major ones being I am not "social" (I don't go to bars, sports, church or anywhere else, I don't play video games at lan parties, I never participate at company events, etc.), I think too much (better not talk economics, politics and especially religion in front of me), and I always say what I think regardless of who I speak to (or, when upset, who I yell at).

Without a job I cannot finish my degree in mechanical engineering at CTU.

Without a degree in mechanical engineering I have no access to labs with air tunnels and fancy software. There is no Blender extension to calculate eddies, just basic fluid dynamics. I can't afford Autocad or similar software, not even counting the specific extensions for advanced particle simulations. I can't write the extension myself because I am not good enough. I mean I can code in 7 programming languages, but I got no lab, no simulations, and my knowledge on the subject is too shallow.

So I do as I can. I will now aim for another IT job, this time in Java that is said to be "in" (meaning I can get a job regardless of my reputation), and I will try to keep my mouth shut as long as possible, while making and selling my arrows to anyone I can.

kokes · June 2014

Re: Wind turbine in high winds

Hi,
I just wanted to hop in to let you know that everything is fine, but it takes me forever. I finally have arrows that I consider marketable. I don't have them documented yet, but I am here to show you pictures and tell you about interesting things I came across so far.

Check out the turbines I made so far:

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I tried to order them chronologically. The oldest ones are top right corner, newest ones bottom left.

Two turbines on upper right corner aren't very functional, I made them just to test the geometry before writting a program with 3D output. One of the turbines has airfoils attached to it, but they are yet parallel to the surface, like Gorlov's VAWTs.

Third turbine is the one that I was dropping from my parent's baclcony, and the one that got shot by pro bow.

Next two turbines were made for testing various twists. I built three, but lost one.

Next row of turbines were all cast. I was learning how to mold the shape and also testing various materials.

Next row is my master turbine and then two pieces with pre built airfoils, first one cut up to small pieces and then one large profile that I twisted later on and secured with glue.

Third turbine from the end got damaged, I was testing different method of making airfoils. It saved time, but the results weren't worth it, as you can see. This turbine rotated accidentally in my hand when I was carrying it around on a windy day.

I will talk about the last two turbines in a separate post since they are the most interesting ones.

kokes · June 2014

Incorrect turbine and physics

First turbine I would like to present is an incorrect one. Let me first demonstrate how it should look like. These are pictures from my patent application that I also used in my turbine presentation video that can be found on Youtube. The turbines on the right side are combined turbines that are built nowadays, and I used them just to demonstrate the lift and drag action.

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Note that my turbine works both on lift and drag action at the same time. It is important is to make the turbine in such a way that both lift and drag will spin it in the same direction, not fight against each other. But I make mistakes sometimes, and that is exactly what happened with this turbine:

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Tip of the arrow would point to the right. The blue lines mark the hump at the top frontal side of an airfoil. Note that the airfoils would pull the turbine blade to rotate upwards, while the drag action would push it to go downwards. In a real life the situation looks weird. First the turbine acts like it doesn't know where to rotate, it wobbles. At lower speeds the lift action ceases to exist and the turbine starts to rotate due to drag action that becomes dominant. Very similar to what I described earlier. It would be interesting to see the action in very high speeds that I am unable to achieve at the moment.

Also note the shape of the blades. They are thicker towards the ends and thinner in the center. That is to make the turbine less affected by drag and more lift powered. I did it to make the arrow more aerodynamic. If I wanted slow strong turbine that would be drag powered mainly, the blades would taper towards ends, and would be thickest in the middle.

In the next post I will show you my latest two turbines, both of which I consider marketable.

kokes · June 2014

Correct turbine

So here she goes, my first turbine that I am content with:

Attachment not found.Attachment not found.

This turbine works as an arrow for my weak bow, at any speed it can achieve. In other words upper limit unknown. It flies on a par with original Easton Jazz 1214 arrows considering the distance. Which I find really satisfactory, as the original arrows were supposedly designed by experts in aerodynamics from NASA. Achieving the same distance is a great success in my eyes. The turbine is quite twisted, as you can see from the frontal view. That makes the turbine start at comparatilvely low speeds. Freefall experiments indicate the start up speed of 15 kmh^-1.

By then I knew how to surpass the original arrows, so I did with this one:

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It is the exact same thing as the one on the top, but it is less twisted, which makes it less affected by the drag action, and therefore more aerodynamical. Look at the front view of this turbine and compare it with the front view of the twisted turbine. You can clealy see that surface of an airfoil that you can actually see (doesn't point directly towards you) is smaller in the bottom turbine. This arrow flew 24% further than the original one. It is not as much of a difference as with my previous tests, but this arrow is much better in overall performance. It never flaps at any speed, so its path is very predictable start to end, and it can actually be used as an arrow that is to hit something. I suppose the distance difference will vary with speed. As the drag becomes much greater at increasing speeds, my arrows should fly further and further at absolute numbers and also at the basis of percentage. The turbine starts rotating at about 19 kmh^-1, and will therefore work more as an arrow, while the upper one will be better for harvesting wind energy.

mike95490 · June 2014

Re: Correct turbine

How do you orient these as a wind generator ? Will they be on a mast, or rotate to track the wind direction ?

kokes · June 2014

Re: Correct turbine

mike95490 wrote: »

How do you orient these as a wind generator ? Will they be on a mast, or rotate to track the wind direction ?

Hi Mike. I want to use the funnels that will orient themselves against the wind like a windsock. The only difference will be that mine will be rigid, more or less, so that they can support the weight of the turbine located in the rear narrow section. The tower itself will be floating on water, which will act as a bearing. For pictures and details see post #10.

Now that I think about it the turbine I made incorrectly could work as brake-itself turbine in high winds, even without the tilting tower. It will simply stop spinning in too strong of a wind. It probably won't be needed to brake it at all, but it could be done in this way.

BB. · June 2014

Re: Correct turbine

Ducted fans (shrouded turbines) do not seem to scale well or work as theorized in actual use. Here is some information:

www.wind-works.org/cms/index.php?id=117

-Bill

kokes · June 2014

Re: Correct turbine

Wow, Bill, what a great resource! Thank you! Jan

They had only a model in a wind tunnel and computer simulations to spin their story to the media. They didn’t erect a prototype...

Now that was stupid. People believe in computers too much nowadays. They only slowed me down so far, everything I achieved I achieved with scissors, paper, pencil and glue. I will continue doing so, even for the large prototypes. Gotta go read some more now.

BB. · June 2014

Re: Correct turbine

Computer models only work (to a degree) when you understand the physics enough to model...

Otherwise, computer models are just curve fit simulations (like the whole global warming being predicted by "climate scientists"). They are only as accurate as the curves they fitted. And almost never (never ever?) work out when extrapolated beyond the inputted range of data or outside the "training data" timeframe.

-Bill

pleppik · June 2014

Re: Correct turbine

BB. wrote: »

Otherwise, computer models are just curve fit simulations (like the whole global warming being predicted by "climate scientists"). They are only as accurate as the curves they fitted. And almost never (never ever?) work out when extrapolated beyond the inputted range of data or outside the "training data" timeframe.

The physics of fluid dynamics are pretty well understood, and CFD simulations have been in widespread engineering use for decades.

You still want to validate any computer model against physical experiments (including the climate models you deride, which match actual climate data going back over 20 years--it turns out that "climate scientists" are in fact actual scientists), but as an engineering design tool it's really hard to argue that CFD isn't good enough.

Especially in this case when you're dealing with ordinary air at slow speeds. Nothing weird like hypersonic flow, ionization, magnetohydrodynamics, etc.

BB. · June 2014

Re: Correct turbine

I agree, engineering models (fluids, air) are based on know physical behaviors.

Climate models have yet to model the complex/chaotic nature of the earth's oceans, earth, and atmosphere. The vast majority of the models diverge very quickly:

http://www.drroyspencer.com/wp-content/uploads/CMIP5-90-models-global-Tsfc-vs-obs-thru-2013.png

Generally an indication that the model has the negative feed back effects wrong (or are missing fundamental divers/inability to model on a fine enough scale to match the real world).

The earth is going through a warming phase since the little ice age. On a larger time scale, the sea level has risen. A little history that we have been taught in San Francisco:

San Francisco Bay's History Like most estuaries, San Francisco Bay is a very young feature, geologically speaking. Twenty thousand years ago there was no bay. At that time the world was in the grip of the last ice age, and much of the planet's water was frozen into glaciers that covered a large part of the northern continents. With less water to fill the oceans, sea level was nearly 150 meters (over 400 feet) lower and the Pacific coastline was 30 km (20 miles) west of where it lies today. Imagine having to travel all the way to the Farallon Islands to go walking on the beach or surfing in the ocean! The Bay itself was dry land, with rivers running through the low-land areas on their route to the sea.

As the glaciers melted over centuries, the ocean waters rose and the shoreline crept back eastward, toward land. By 10,000 years ago the ocean had spread inland through a gap in the outer Coast Ranges that we know today as the Golden Gate (Figure 1), and seawater began to fill the Bay. For thousands of years, sea level rose rapidly at nearly 2.5 cm (one inch) per year, advancing the shoreline progressively inland. Several thousand years ago, the rate of rise slowed and sediments began to accumulate in the shallows faster than the sea could cover them. These sediments supported the expansion of tidal mudflats and marshes along the Bay's shores, whose vast extent was recorded in the last century, before modern civilization began to reshape the Estuary. We will look at the effects of human modifications on the Estuary in subsequent parts of this exercise.

150 meters * 1,000mm/meter * 1/20,000 years = 7.5mm per year sea level rise per year...

4.4x the current "short term average" verses that of the last 20 millennium.

There have been lots of changes to the earth over the millions and billions of years, let alone a few 10,000's of years.

We will have to adapt. Worrying about a 1-2 degree C change in average temperature (what ever that means) over a century predicted by computer models vs the 10-20+C daily/seasonal temperature swings we have today

-Bill

kokes · June 2014

Re: Wind turbine in high winds

Let me get back to the computer models a bit. I am not entirely against them, they are just inconvenient for me. I simply believe I can achieve more accurate results faster and on a tighter budget by making real life models and prototypes. I don't need too much of a structural strength for a full scale prototype, I just need to test it in mild conditions. I can then mold the model, burn it out (paper and glue both burn like crazy) and cast it out of whatever I wish for more Gestapo style experiments. I now know thanks to Bill that a large unit may behave differently from a small one. I always thought it was just the flow speed, viscosity and density that mattered.

I am not sure who was the greatest turbine maker who ever lived, but I would bet on Francis. He was the first one who promoted modelling in engineering, for turbines at the very least. He made dozens of little models and simply picked the best of them. His turbines are still commonly used today. I want to take the same path as it works and can be done with simple tools.

kokes · June 2014

Re: Incorrect turbine and physics

I was reading some more from the link Bill posted. Sad reading. It seems the green energy area is full of people tying to find investor at whatever cost, scam being a major tool of the trade. I wasn't aware of that. I am glad I don't need to join the pack. I can use my turbines as an arrow accessory to make them fly further, more accurately and less affected by side wind. Top of the line accessory fletches sell for over USD 20 apiece, at the production cost of about USD 1. There are over 2 million bow and arrow hunters in the US alone. But I will most likely sell only few arrows, I have a deadline to pay the patent fees on July 7th, and no way of paying them. Most likely I will not meet the deadline, my turbines will become open technology, and only fans will buy them from me. The rest from China I guess. Anyway, any income should be enough to get me going building large units and turining some other invention of mine into gold. And even the reputation alone should be good enough to do the trick for me.

pleppik · June 2014

Re: Correct turbine

BB. wrote: »

Generally an indication that the model has the negative feed back effects wrong (or are missing fundamental divers/inability to model on a fine enough scale to match the real world).

The earth is going through a warming phase since the little ice age. On a larger time scale, the sea level has risen.

There have been lots of changes to the earth over the millions and billions of years, let alone a few 10,000's of years.

We will have to adapt. Worrying about a 1-2 degree C change in average temperature (what ever that means) over a century predicted by computer models vs the 10-20+C daily/seasonal temperature swings we have today

-Bill

I guess I'm a little confused by this response (and sorry to the OP to go off-topic).

Are you saying that:

1) The Earth is not actually warming,

2) The Earth is warming but it's not caused by humans, or

3) If the Earth actually is warming it's not that big of a deal?

It seems that you said all three, can you please clarify? Thanks.

Cariboocoot · June 2014

Re: Correct turbine

pleppik wrote: »

I guess I'm a little confused by this response (and sorry to the OP to go off-topic).

Are you saying that:

1) The Earth is not actually warming,

2) The Earth is warming but it's not caused by humans, or

3) If the Earth actually is warming it's not that big of a deal?

It seems that you said all three, can you please clarify? Thanks.

Which is what we are told by the media almost daily: all three.

And now that is the end of the climate change discussion because it is outside the venue of the forum.

kokes · June 2014

Re: Correct turbine

I was testing some more today. I used different arrows, since I lost one of the original ones. The new arrows are harder to compete with. Original arrows had slight twist to their fletches to make them fly straighter (same principle as stabilisation of satellites). The turbine was slowing the original arrows down noticably, as one would expect with turbine, especially with drag powered one. The new arrows on the other hand have straight fletches, so they fly with more flapping but further (same principle as stabilisation of rockets).

There are several things that I discovered today.

Concerning turbine:
It is stronger than I expected. One of the tests was that I mounted it to my control arrow that had fletches. It spun them so fast I wasn't able to recognize them. To me this means that my turbines are too strong, I can make them much weaker and they will still be good enough for stabilization. And I will need to do that, because I am most of all interested in distance.

Concerning ovservation:
The observation of the turbine became impossible. It spins so fast I cannot see it at all. Maybe someone less shortsighted could see it, I surely can't. I only derive whether it spins or not from the behavior of the arrow.

Concerning distance:
My rotating arrow and my control arrow were landing very close each time. I was unable to determine which one flies further. Maybe if I used carriage mounted crosbow I could get more exact restults, right now I can't. This means two things for me:
a) I am on a par with NASA once again. And I know how to improve once again.
b) I am not yet ready for fancy bow, it would be waste of money now. I need to improve first by making the turbine weaker.

Concerning flight characteristics:
My control arrow flies like a snake, flapping here and there in sinus like curve. My rotating arrow flies nice and straight. Arrow with no stabilisation flies worse than the control arrow, the curve is not sinus but a pure chance.

Concerning turbine placement:
I am unable to tell which is better, whether front mounted, center mounted or rear mounted turbine. It is all very close. My turbine now spans only 60° on the horizontal axis, so it is possible for it to avoid both bow and archer's hand. My main argument against rear mounted turbine "it will cut your hand" is no longer valid. I still like to keep it up front. The propeller of a ship was proven to be more efficient on the rear. Horizontal turbine and a propeller are virtually the same thing, only inverted. So to me it makes sense to invert the placement, ergo mount the turbine to the front. Not proven, just my feeling.

Concerning turbine destruction:
I finally figured out the way how to make turbine so that it is strong enough to grip on a shaft for rotation and so that it doesn't slide to the rear while airborn, but at the same time weak enough to allow the arrow to slide through upon impact. I tested it few doesen of a times shooting for a distance and I also shot full strength to the bale of hay that was laying around from about 6 feet away.

Concerning me:
I am tired and I really need to catch up with programming. But the deadline is approaching, so I don't think I will rest for long. One of neighbours of mine said she had a digital camera, so I will try to convince her to go shooting with me this afternoon. The rotation will not be visible, but the trajectory and behavior of arrows most likely will.

inetdog · June 2014

Re: Correct turbine

Some digital cameras have a high frame rate mode (slow motion video) which might help with your observations. As long as the light is good enough for short exposures.

kokes · June 2014

Re: Correct turbine

inetdog wrote: »

Some digital cameras have a high frame rate mode (slow motion video) which might help with your observations. As long as the light is good enough for short exposures.

I absolutely agree. Today I was recording. I used Panasonic LX2. I am not entirely happy with the results. Maybe the videos could be viewed in slow motion or frame by frame. I will try it later on, I just hopped in to upload the videos. The flight itself is visible, and so is the rotation in at least one of the clips, but not the whole trajectory. I got the girl's phone number, I will take her shooting once again ASAP.

The videos need to be resized, trimmed and uploaded to YouTube. If you like you can download them as a zip file of movies at full res here.

Total size of files is about 400 MB (I believe it is 848 x 480 pixels @ 30 fps, but I am no photography expert).

kokes · June 2014

Arrows moved

Hi,
I just wanted to let you know that I didn't do too good of a camera job, and even though I have seen the girl again, archery wasn't ivnolved at all. The arrow testing will be since now in hands of Jörg Sprave who agreed to help me out and I am sending him first arrow today. He has all the equipment I lack, besides bows and crossbows also cameras, speedmeter etc. His channel at youtube is already dedicated to shooting all kinds of crazy things, my arrows will come next.

Since now I will probably talk only about turbines here. I have the funnel ready along with axis and turbine and bearings, I need yet to connect all that and then I will start generating electricity, which should me more of an interest here.

PS: In the previous post I gave you link to the videos. Jörg told me that the videos can't be downloaded due to password. You don't need password, just click yellow Download button and then click column in the center (free access), fill in the captcha, and your download will begin.

PPS: Never mind about NASA, I just searched the google and I couldn't find any results. Sorry I ever it.

Wind turbine in high winds

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