Anemometer Tower

[Jerryflyguy21]

So I'm starting out in the RE wind world and my first step is to install an Anemometer tower w/ a Data Recording system. I'm going to be placing two recording heads, one at the top of the tower and one 1/2 way up. I can compare the data between the two and asscess if what height of tower is really required. [at least 'best guess' from SOME data is better than a 'heck I'll try XYZ tall and see how it works']

My plan for a tower has been to use chain link fence 'top rail' which is galvanized and has a 1.875" od x 0.100 wall in 21ft sections. I can buy this as simple tube and then use a 7" collar to join the sections, or I can buy it w/ a swedged end such that each pipe section just stubs into the next [not sure which design is more structurally apealing].  I have spec'd in the guy wires [1/8" aircraft cable fab'd directly as complete units from a local cable/rigging supplier, complete w/ turn buckle ends etc]  I was planning on putting a guy every 30ft starting at 30ft.

O/A tower height will be ~160ft with 5 sets of guys wires. The spread of the guy wires from the base of the tower will be 30ft [measure out from the base of the tower to the guy anchor] with all 5 guys coming to the same anchor. 4 guys located radially around the tower at 90deg between each guy set.

I have the option of putting up to five sensor heads on the one tower or building two towers and putting them in different locations [as in several miles apart]. I currently have a few heads but could easily buy more if I decided I wanted them spaced closer together up the length of the tower [creating a 'denser' data field]

Just thought I'd put it 'out there' for others to review and advise per their exeriance. I figured it was [generally] better to ask 'first' before I leap in the wrong direction. Everything in the design is quite 'fluid' right now.

Btw if anyone is looking for Data recording Anemometer's, I purchased these from Barani Design <http://www.baranidesign.com/products.html> No affiliation other than [thus far] they 'look' really well. We shall see how well they operate in the real world of ice and snow.

Thanks in advance!


JFG

[TomW]

Pretty pricey little units there.  I might venture the guess many of us have turbines flying that are cheaper than that.

Just from here.

I seem to recall that Bergey used those same tubes for turbine towers and had some coupling collar and guy mount point arrangement. Might be worth looking at.

Tom

[just-doug]

how are you going to stand this steel tubing up?if you tilt it up i expext at between 20 and 40 degrees it will buckle fast and bad.like in several places

[Jerryflyguy21]

Thanks Tom, I'll look into Bergey and see what I can find out! By collars I assume your talking they used a collared joint vs the swedged joints?  I had wondered if the swedge point might cause some concern as a failure point. I even considered doing both [collar over swedged]. If the collars are cheap enough it seemed like good insurance.  The data loggers certainly are not just 'buy from walmart' el cheapo unit's. However in the same vein, they are cheaper that all the other unit's out there that have similar capabilities that I've seen [ie: Madgetech, APRS, Inspeed etc...] plus they come w/ some decent software for site assessment and breakdown of wind quality etc. I am planning a few more kW than the average small DIY install so, it's worth spending a couple grand up front to investigate if it's viable or not.

Doug, I plan on using a gin pole to stand it up, it would need to be 30ft long and would have one set of guy wires connected to the end of the pole.  The entire tower would weigh ~ 330lbs so it isn't exactly a monster weight wise. Recommendations on what would be a better setup?

JFG

[fabricator]

Well for one thing a thirty foot gin pole is fifty feet too short, basic rule of thumb is the gin should be around fifty percent the tower height, my feelings are you are going to be trying stand up a piece of spaghetti cooked el dente, it might work but it sure could get exciting in a hurry.

[TomW]

how are you going to stand this steel tubing up?if you tilt it up i expext at between 20 and 40 degrees it will buckle fast and bad.like in several places

The same way we raise our turbines on tube towers. We use guy wires and winches to tilt them up. A little research should yield that process.

Tom

[Jerryflyguy21]

Fabricator, I guess there is a simple way to test it.. just buy the tubing and try and stand a shorter pc using the same but scaled [geometricly the same] gin pole and see if it works. Quick/dirty math says it should be ok but I guess the proof will be in the puddin'

Btw so if the rule of thumb is for the ginpole to be 1/2 the height of the final tower what other rule of thumb should be applied to spacing the guy wires?

Curious

JFG

[birdhouse]

jfg-
that's a ton of money to just get info!  have you looked at wind zone maps?  what is your place by what the maps say?  if your in a zone 3 or better, the money may be better spent on the actual tower. 

what kind of trees/topography would you be "fighting" to get up to the good wind? 

just from top of the head thinking (no calculator) i'd guess the gin pole would be on the short side and the guy radius being too small.  if it were ME, i's go at least 50' on the guy radius, and run 3/16" cables for JUST the top set of guys.  they take the brunt of the force.  the lowers just keep the pipe straight.  i'd also be a little nervous about the guy locations up the tower not being centered on the pipe joints.  you may even need two sets of guys on the gin as it's so thin... 

my turbine tower is 70' and uses a 32' gin pole and 32' guy radius.  i think it cost less than your proposed test tower. 

you can watch it go up here: http://www.youtube.com/watch?v=ARgEb7CSDtw

do some research on back-haul leashes on tall towers.  they can prevent your rig from buckling during the raising process. 

just some thoughts

adam

[Jerryflyguy21]

Adam, thanks for the reply.

I guess if someone was wanting to make a simple setup on the cheap they could do alot better than this, in my situation the pipe is only worth $350 the guys are twice that much and then there is the data logging stuff.

This is less than 2% of the cost of my entire install, should I go ahead with it so..  not really a concern in the big picture [well a bigger concern would be incorrect data or location for the same setup producing zilch for power]

I live in a zone 3 w/ 6.7m/s [so says the wind map] Weibull avg [K=1.92].

There are two things I'm trying to nail down, where is the best compromise for tower height and what is my wind speed compared to the wind atlas.

My topology is about like your kitchen table   with little to no trees [farm/grazing land]

Do you have any links to sites which give some form of dimensional ratio for gin pole sizing etc?  I've looked [google] and didn't find anything.

I've tweaked my numbers a bit to have a 50ft gin pole [from 3 x 3 0.125 HSS  x 48 ft long w/ added plates for each end to pivot and carry the cable connections]

My basic [back of the napkin] numbers for the max loads during the first pull on the haul line using the above gin pole.

4 guys each located on a tower tube joint, each guy is then spaced at 40ft [the top guy would be attached a bit short of the top of the tower, say 5ft short]
Top guy is under 293lb tension load
second from top is under 234lb
Third from top is under 170lb
the bottom guy is under 115lbs

The entire tower weighs ~360lbs and this is assuming there is no load carried by the bottom [ground] connection.

Compression load on the gin pole is 709lbs [radius of gyration would allow a 1463lb load here w/ 2.0 factor of safety {FOS}]
Tension load on my haul down cable would be 1002lbs. If I was to use a two line block/tackle this would be halved [or 501lbs].

The 1/8" steel cable used in my guys is rated for 1700lbs tension. So at worst load the top guy has a FOS of 1700lb/293lb=5.8

Wind loads for a 25m/s wind speed on the upright tower is actually less than the erection loads so I've assumed a 'good' condition there.

Compression loads on/in the tower tubing run it up to ~1500 psi in the material [tubing] which if properly stabilized with the guys on either side should not be an issue.

All I need to do is find a cable set [or rope] that would carry the haul down load and I'm good to go... as far as I can tell? I'm also planning on adding a stabilization rope(s) from the top of the gin pole down to each of the two adjacent guy [ground] anchors to ensure the gin pole stays inline w/ the haul line and the guy connections up the length of the tower, I'm not sure if it's needed but it would seem that there is a possibility of the gin pole wanting to drop to either side.

Am I missing anything [not that I'm expecting anyone to re-run my numbers ]

JFG

[birdhouse]

jfg-
the "standards" come from reviewing many pdf's from all the different companies, and comparing/contrasting the parts you like from each system.  or atleast that's how i designed my tower.  i don't think i've got the ability to do calcs like you're able to do, so i built as well if not better than what seemed to be the industry standard.  but this is all talking about turbine towers, not anemometer towers...  a whole different ball game.  WAY less loading on an anemometer tower...  though still no trivial task to keep it a safe operation. 

it seems you're planning on putting up some pretty big commercial units on your windswept plain.  again, just off the top of the head, if you're a true wind zone three with ZERO trees and or obstacles, i wouldn't see the point of testing wind speeds @ over 100'  sure they might be slightly higher, but the tower cost for a BIG turbine would probably not be worth it. 

you're kinda getting into realms beyond this forum.  not that folks won't wanna give input, but IIRC the tallest homebrew tower i've read about on this forum was 120'.  these heights are usually used to get above trees or topography.  since it sounds like you've got zero of these issues, i'd guess a solid tower of 80' would get you extremely laminar airflow with minimal disruptions from turbulence.  kind of the most bang for your buck.  i honestly don't think monitoring or thinking of constructing a tower above 100' will do much for you, especially if your turbine is going to be some giant. 

the GE and Mitsu units up near may ranch have a 200-300' blade diameter and sit with a hub height of 200-300'  i'm guessing you're not talking about putting up units of this size rage, but if you are, i'd proceed with the 160' anemometer tower.  it will be very useful information for megawatt+ sized machines. 

if you're considering a few 10kw bergeys, i'd just scrap the cost of monitoring and plunk in some 80' towers. 

where do you live if you don't mind me asking? 

my home is Portland, OR but my ranch is outside of Bickleton, WA

adam

[birdhouse]

almost forgot, a friend of mine...  he's one of those weird computer folks that isn't very social...  yada yada...  he came up with some crazy computer algorythm based on wind maps and gps location and tower height that is supposed to be amazingly accurate.  it gave me 12.56mph average at my spot with a 60'stick. 

he developed this technology for a wind company that is currently in business, but he'll run number for me "through the back door" for $5 per run.  let me know if you're interested and i can probably get him to run your numbers.  i think he still has rights to the program even though he built it specifically for a turbine company.  PM me for more info. it might be good info to confirm what you think you've got before measuring at extreme heights. 

adam

[Jerryflyguy21]

Adam, I am looking at putting up some commercial units so I'm doing my homework such that I can prove and answer all questions as the approval process [and financing as I'm not paying for all of it out-of-pocket].

I don't expect that I will be putting up a 160ft Turbine/tower... no no..  I'm looking for data to prove that I DON'T have to put up a super tall tower. How do I conclusively prove this?  Measure it and present cold, hard numbers.

I don't expect to get over 100ft with the units I'm planning to install. I realize I'm probably outside the relm of the forum but also know that there is lots of experiance here so it's worth picking brains were possible. I've also been D/L'ing tower erection manuals from various manufactures to get some ideas on how the retail guys go about this process. Good reading for sure.

The first unit I plan to erect will be a fair bit larger than the 10kw Bergeys and from there we'll just have to see how the economics of it work out.

I'm located in South central Saskatchewan [Canada].  I would certainly be interested in seeing data on my location from your friends fancy number cruncher... $5 for a data run is pretty cheap [concidering ... ]

I'll shoot you a PM

JFG

[SparWeb]

At some point in the discussion did you get away from 1.875" OD tube?  I do not believe you can put that under the compression loads your tower will impose and survive.

One half-turn of the turnbuckle could add 100 pounds tension to a guy wire, and not a lot of us are anal enough to actually measure the tension often.  
Expect them to be really really tight.  
That pre-tension is always there, and wind loads only add to it (on one side that is).  For my calculations I used 500 pounds + wind load.
When adding up the loads in the guy wires, you have to multiply the cable tension by the number of guy wires per station (4 in your case) and the sine of the angle.  
500 Lb X 4 X sin(63.4) = 1789 Lb at the top station.
Work my way down...  Add the wieght of turbine and the tower itself...   Your lower tubes are subjected to over 4000 pounds compression.
In sections 21 feet long the tube sections have to be 6 inches diameter or something.  Otherwise it will dance and wiggle like a belly dancer.

Please be very careful.  We all want to see you succeed.  100+ foot tall towers certainly can be built DIY, but it takes a lot of care to do it safely.

You can estimate the difference between a 100 foot tower and a 50 foot tower.  You have the average wind speed.  Presumably the statistics quoted an elevation with that average.  You've already described the local "roughness length".  Everything you need to compute the effect of cutting the tower height in half.  If you can live with the difference, you have suddenly made the tower 1/2 as tall, and 1/4 as difficult to build (and 1/4 cost, too)

Am I missing anything not that I'm expecting anyone to re-run my numbers

I re-run the numbers on people sometimes, but I think I'll just shoot from the hip today. 

[Jerryflyguy21]

Thanks Spar, I'd neglected to think about the pre-tension numbers.    Hrmm.. well maybe I'll have to do a bit more in the guy wire dept. 

I know I could calculate 'the numbers' for elevations higher than my tower but I would really prefer [from a "I've actually measured it" perspective] that I had hard data vs 'estimated'.  I hate getting smacked by some variation in my estimates etc etc on install performance. Not that I'm looking for a ROI down to the third decimal point.. just that having the actual data and being able to calculate it are similar.. but not the same when it comes to standing behind the numbers.

I'll have to do some more stewing on this.. [too late to do it tonight ]

JFG

[birdhouse]

Otherwise it will dance and wiggle like a belly dancer.

spar i was hoping you'd chime in on this as your the resident structuaral engineer on towers.  i agree that pipe is too small just based on experience.  i also think using 3/16" guys for the top would be absolute minimum.  

jfg-  are you talking 25kw machines?   who's the brand if you don't mind me asking?  

adam

[Jerryflyguy21]

Ah well.. a new day and a fresh new look.   I did some more radius of gyration numbers on a 40ft colum length [guys located at every second joint] of this 1.9 od tubing and I show an allowable load of 755lbs  w/ a FOS of 1. [ assuming top and bottom locked in position which really isn't probably the 'official/usable' case]

I did the full numbers for the tower as far as tension was concerned, assuming 100lb tension on each cable, the tension in any direction of a wind load equal to the haul up load of the gin pole [so one or the other] and the weight of the tower I come up with a colum load of 2406lbs. [not including the weight of the cable btw]..  so assuming a min FOS of 2 ... I'm screwed. 

Thanks Spar... saved me from a big bang.

So.. more numbers..

100ft tower... has 1607lbs compresional load on the base of the tower [lowest tube]. If I was to move my guy down to the first joint [@ 20ft] and every 20ft there after, w/ the last guy spacing being a bit longer and ending 10ft from the top of the pole, I would have an allowable load of 3021lbs [FOS=1].  This is still with a 50ft gin pole/guy anchor spacing out from the tower base.

So...  what would an 'reasonable' FOS on a tower be?  1.5?? I'm w/in spitting distance of a FOS of 2.  One other thing that comes to mind is harmonics due to wind speed.  I'm not well versed in calculating harmonics of a compressional load member but I do know it 'could' matter.

Btw cable tensions range from (140lb [haul up load] + 100lb [pre-tension])=240lb on the highest guy down to 170lb on the bottom guy... so I'm thinking the 1/8" cable as spec'd should work.

Curious as to your thoughts!

Thanks again for the 'tensional load' reminder... thats what happens when you 'run numbers' after a 16hr day 

Btw, I've always been amazed at the load carrying cap of colums..  I am involved [on a commercial level, one of my day jobs is "industrial desing/project managment" for steel fabrication] with building storage for ag product on colum supported structures...  a small  6 x 4 hollow tubing [~ 10ft long] carrying 30-40,000lbs with a total load on the structure of nearly 3/4 million pounds... just boggles the mind 

JFG

[SparWeb]

Don't take this the wrong way, but I really think you should do the check on wind speed gradient.  Especially in Saskatchewan.  I live out in the flatlands, too.  Just a few cows standing between me and the horizon (when not looking toward my house of course).  Somehow you've picked 100ft for your tower and everything's getting decided from there.  Revisit the original choice and you will save a lot of money and hassle.  The math is not hard.

The compression load on my 45 foot tower is ~1500 pounds.  3" pipe.  It's big enough, structurally, but it still dances around more than I'd like.

Think factor of safety = 4.  Or more.  Please.

Don't stop at radius of gyration.  Go all the way:  column buckling critical stress/load.  Hint hint google hint hint.

[Mary B]

What about ice/frost loading?

[Jerryflyguy21]

Spar, I didn't do anything with buckling but the critical stress is 4029psi which is within limits for even cheap china steel. Did those numbers when I'd done the original Rad-Gyration numbers [I cheat and have a whole spread sheet setup for these calculations].   I'm no engineer so this is all 'self taught' stuff but [at least what I've done thus far] isn't too difficult. I'm going to make a couple calls and see what 3" tube is going for locally [and what is avail] if it's not that large a premium over the 1.90" then I will just upgrade to, use profile cut butt flanges and 'fo-get-about it'

I am hoping to keep my actual turbine tower inside of 100' [80 would be even better] but I would 'prefer' actual data over extrapolated estimates. It's just easier to stand behind those numbers vs phrasing answers starting with "We estimate that.... " it just doesn't carry the same weight compared to "Based on our measured data at that hub height.....".

Mary, I've done the complete number run-down on probable ice buildup on both the 'impact face' of the tower [cross sectional area] as well the same on the guys. This breaks down to 216.5 'possible accumulation' days out of the year [assessed using a standard bell curve with the last 116yrs of recorded data and assuming it's not a leap year]. Worst case is a wind direction of 22.5 deg off of alignment of the guys [that gives us 4 quadrantal 'worst case' wind directions], is blowing at not more than14.25mph w/ a dew point spread of not more than 1.31deg C. The average [measured on a per minute] temp must not exceed the range of -8.22 to -2.64 Deg C  [or 264.93 to 270.51 Deg K]. There is a progressivly lower ice/frost build up due to increasing 'impact area' and the I.C.E. theorem of "Accumulation/Catch Rate vs Speed/Section Profile". That combined with the increased drag due to roughness buildup of frost or ice on the tower [C<sub>D on the pole increases by approx 106% at worst case] will only nonulple [thats 9x] the accumulated loads. The upside is that the additional accumulation of ice/frost will actually increase the load bearing ability of the tower due to additional stiffness and cross sectional area such that this accumulation isn't a concern. The 'worst case' is when this happens and the birds [sparrows are the only native bird in the area during the 'potential ice accumulation' segment of the year] start landing on the guys coupled by the local reindeer using the guys as 'back scratching posts' at that point [assuming were talking about a yearling reindeer] we're ok, as long as an equal number of birds land on opposing guys and the reindeer use opposing guy wires and they must be scratching 'in time..'.  If they use any other combination of guys or scratch 'out of time' there will be a complete failure of the of the welds on the embeded anchor eyes [the anchor points!?! believe it or not!] and the tower [depending on the prevailing wind and which side has the ice/frost accumulation... will most likely fail...  spectacularly.. the upside is I'll have free reindeer steaks and sparrow breasts for the rest of the winter, if the tower falls as planned.   

All kidding aside, if ice and snow are going to bring it down then it doesn't have enough FOS build in... plain and simple.. [at least as I see it.. Spar might have a different perspective ]

JFG

[Dave B]

I've said it before and when it comes to towers and discussion here I'll say it again. If you do not have the skills to properly design and construct a tower for a specific use do not do it yourself. Hire a professional Engineer to do this or at the very least purchase a tower from a certified manufacture that meets your required specifications and then hire their Engineering services to help you get the job done safely. With the money you apparently have to invest I do not understand why you would want to do this any other way risking life and limb with so many questionable design factors and uncertainty. There are many experienced people on this board and it can be and is an amazing resource for information that's for sure but ultimately you are responsible for your own safety and for others as well. A quick search on tower failures can be a sobering experience. Sorry to preach but this discussion just seemed too "iffy" for me not to voice my own opinion. Please be safe,  Dave B.

[Jerryflyguy21]

Ya.. I suppose going into numbers on the back scratching loads from reindeer could be seen as 'suspect'.    A guy has to have fun at some point 

JFG

[B529]

I've said it before and when it comes to towers and discussion here I'll say it again. If you do not have the skills to properly design and construct a tower for a specific use do not do it yourself. Hire a professional Engineer to do this or at the very least purchase a tower from a certified manufacture that meets your required specifications and then hire their Engineering services to help you get the job done safely. With the money you apparently have to invest I do not understand why you would want to do this any other way risking life and limb with so many questionable design factors and uncertainty. There are many experienced people on this board and it can be and is an amazing resource for information that's for sure but ultimately you are responsible for your own safety and for others as well. A quick search on tower failures can be a sobering experience. Sorry to preach but this discussion just seemed too "iffy" for me not to voice my own opinion. Please be safe,  Dave B.

Sound Advice!

[wooferhound]

Here is some more information about Tilt-Up Towers . . .
http://fieldlines.com/board/index.php/topic,143653.0.html

[Jerryflyguy21]

Thanks Wooferhound... read/scanned every link.  Interesting reading    [I'm actually 122 pages [of the current 259] into the wind portion of the site.. just scanning for threads that pertain to me. Lots has been tried or proposed over the years  ]

Being as this is just a simple anemometer tower [zilch for loads other than it's own weight and wind load] I think I'm pretty close to spec for what I need.

Re: Comments from others about doing it right and getting it engineered etc..   While I'm not an engineer, I do engineering numbers regularly in my day job. On the jobs were they need to be certified I do the numbers and then run them by a professional engineer. Sometimes he points out something I've missed but most times he's satisfied w/ my work and planning.   Keep in mind this is a anemometer tower...   it weighs about 25% more than I do.. sure it could still hurt someone if it came down, that is if someone was ever there. Which is very  unlikely due to it's location [well other than reindeer  ]  I'm not thumbing my nose at your comments but keep in mind that I'm not the village idiot either..  From my experiance most things the average joe builds that 'feels right' is one of two extremes.. either WAY to light or WAAAY overbuilt.  It can be shocking what a properly designed structure can hold [the 10ft colum structure I mentioned from work...  has a FOS of 10x and is carrying nearly 3/4 million pounds of weight yet I can pick one up and carry it around.]

I'm not against someone telling me I'm doing it wrong or questioning my numbers but "this 'er pee-lan jus appeers ta bee nut sa goot" comments w/out data to back them up are neither helpful or directional as far as proposed solutions are concerned.

JFG

[SparWeb]

comments w/out data to back them up are neither helpful or directional as far as proposed solutions are concerned.

Please don't cross that line.
We are not your engineering review committee.
We know a mistake when we see it.
It's not our job to do the work for you.

Read carefully "DIY" = "Do It Yourself"

Please be careful and don't let the macho get in the way.

[Dave B]

Well said,

  As in my previous comment about this post I felt a bit anxious about the project from the start. The more I read the more I think you have hit the nail on the head about macho or more simply maybe ego. The poster has admitted several mistakes already in calculations and omissions of critical design critera, it's obvious he is looking for Engineering services from the board and as he states some here have already saved him a big crash. Fishing, plain and simple, throw an idea out there with obvious faults to gain interest and feedback then run with the information. There is no humor in tower accidents and this casual attitude of "oh well" if it happens nobody should be around or I'll have fresh meat to eat with what it kills says it all.   Dave B. 

comments w/out data to back them up are neither helpful or directional as far as proposed solutions are concerned.

Please don't cross that line.
We are not your engineering review committee.
We know a mistake when we see it.
It's not our job to do the work for you.

Read carefully "DIY" = "Do It Yourself"

Please be careful and don't let the macho get in the way.

[TomW]

comments w/out data to back them up are neither helpful or directional as far as proposed solutions are concerned.

Please don't cross that line.
We are not your engineering review committee.
We know a mistake when we see it.
It's not our job to do the work for you.

Read carefully "DIY" = "Do It Yourself"

Please be careful and don't let the macho get in the way.

Well said,

  As in my previous comment about this post I felt a bit anxious about the project from the start. The more I read the more I think you have hit the nail on the head about macho or more simply maybe ego. The poster has admitted several mistakes already in calculations and omissions of critical design critera, it's obvious he is looking for Engineering services from the board and as he states some here have already saved him a big crash. Fishing, plain and simple, throw an idea out there with obvious faults to gain interest and feedback then run with the information. There is no humor in tower accidents and this casual attitude of "oh well" if it happens nobody should be around or I'll have fresh meat to eat with what it kills says it all.   Dave B. 

I decided not to make any attitude or fishing comments.

Well said, guys.

Consultants get paid and you usually get what you pay for..

Just from here.

Tom

[Jerryflyguy21]

Spar I guess I wasn't clear enough when I stated 'I don't expect anyone to run my numbers'    I never asked for engineering review. Simply reports of similar experiences using similar setups would be sufficient. You were more than helpful in your comments and I hope I was clear at the time that they were appreciated.  I can tell you in all sincerity that my comments were not 'macho' or ego driven.

Dave I am not looking for engineering services from the board, Spar was a great help with his recommendations, two of which I've implemented in my design but I wasn't asking for anyone to review my numbers, simple experience in the zone of where I was going was really what I was looking to hear about. The fishing comment is laughable, I'm sure some have tried it but that certainly was not my intent. As to the casualness of my replies, I apologise.. I didn't realize I was talking to an group of uptight cigar smoking muckity mucks.

Tom your right... you do get what you've paid for in life.. [sometimes..] at least until you come to an open forum on-line you get the 'range'. Some have been invaluable [Spar pointing out my missed pre-tension loads, Adam... and your post about Bergey towers etc..etc] others were not worth the electricity it took to send it.

It has been my experience [here as well as elsewhere] that there is a large number of people who read but never post, lots who post but never read, even more that post just to be involved wether they have anything of value to post or not and more still who are there just to cause trouble.

I work in a design environment [Industrial Design Dept of a fabrication and manufacturing company] where forward thinking is promoted, where bringing a negative review for a design or project is accepted when a proposed solution comes with it. Telling someone that you do not think they are doing the right thing and leaving them hanging is just negative and does little to promote a project or maintain momentum. Telling them that "I tried that once and..zxy happend, instead I tried  yxz and had better results." or "I think the more efficient way would be..ABC.. because"  are positive ways of promoting design changes.. 

No matter, I'll just back to reading the forum and glean what I can, obviously asking for input here is going to just cause half the 'repliers' to feel they are getting the short end of the stick and start a beat on the new guy thread. I've accomplished enough in life against the grain of others who said I couldn't do it, this won't be any different.

Sorry to those who are or were offended by my posting, thanks to those who took the time to post a helpful reply.

JFG

[birdhouse]

i think you guys are being awful hard on JFG.  but, i don't make the rules.  i think he's being genuine, willing to calc his own stuff, and eager to learn.  i guess the main difference is he may make profit from this whole endeavor while many of us ask for tower advice just so we can get our homebrews off the roof.

i halfway agree with "if you don't know how to do it you shouldn't".  i understand the safety needed in this industry as every accident puts a bad name on all of us, and life could be at stake.  a 160' anemometer tower could draw attention from all sorts of folks, that may even stand under it for a while.  yes, they'd be trespassing, but i don't think they deserve to die from curiosity or falty engineering/fabrication.  i don't hardly even remember how to do any of that co-sine stuff anymore.  i do feel like my tower is very robust, and don't worry about failure in the least (though it's not 160' either).  people helped me here to a degree without critcism, though i wasn't profiting from my tower either.  

JFG- have you looked into PDF's of commercially made anemometer towers?  this could give you a ballpark/standard to deviate from/calc on.  oh, and why on earth 160' if you think max tower height would be 100'?  seems over shooting the predictions by quite a ways.  do you really think it will be THAT much windier up there?  kite flying could give you some off the cuff feeings for wind speed at various heights!  

just sent off the email to my buddy.  i'll let you know when he gets back to me, and if you owe him any money for the results from his prediction program.  

adam
edit:i don't even really like cigars 

[Jerryflyguy21]

Hey there Adam I have looked at several manuals of commercial wind turbines [Bergey, Raum, endurance etc] and used some of their ideas for mine, of course their unit's are designed for alot more load than mine but...

The 160ft starting point was just simple a number that worked.. was up to and including 150ft [50m].  I had expected my results would show that I only need a tower half that tall but you have to measure the range to find where you need to fit, in that range.  Think of it as a yard stick..   you may only need to measure 28" but you buy the whole yardstick even though you probably won't need the last 8" of it.

I could easily put up a 30ft tower and measure my wind data then extrapolate the estimated wind at the various heights.. [the formula is easy  (V ₂/V ₁)=(H ₂/H ₁) ^theta where theta can range from 0.1 for located over water to 0.6 or higher for built up [buildings] areas.  I expect I'm near a 0.2 [grass land w/ limited trees]... the thing is maybe I'm actually a 0.25  or a  0.15..  seems like small numbers until you do the actual math..  "holla..... the jump from 0.15 to 0.25 means my system could pay itself off a whole 18% sooner!... I wonder which it REALLY is.."    or..   "Cool.. based on the measured data I've got I can see I'm actually a 0.23 but there must be some simplification of the calculations 'cause as I get over 80ft theta actually starts to get closer to 0.34...  guess I'm glad I didn't just GUESS at it.. now I know that for my turbine size I can use blades that are 11% shorter and still be able to use just an 80ft tower!"
The real answer is that I don't KNOW how much windier it will be up at those heights.. but what if I go and install a $100,000 system on a 80ft post and 'gasp'...  it is only generating half of what was expected due to some 'local' issue.. or whatever..  wouldn't it suck if I have to go through Rev 2 and install blades that are 12.5% longer so that I get the power I was planning on? If I have the empirical data to show the wind exists... ya think the bank is going to be more excited about the project? 

Can't wait to hear what your pal says...  all the data I can get and cross reference... the better off I am.. [I think, sometimes it just muddies the water but that is the risk we take  ]..

Btw, don't be too hard on the other guys.. everyone sees things from their own perspective.. Most people here are looking to make something outta nothing and if they can get a little power out of it.. they are happy. They see someone like me and react the same way everyone did when I told them I was building a cnc milling machine big enough to drive a full size car on [or into.. rather]...  I was an idiot then to.. crazy.. nuts.. it was impossible.. it was going to cost too much.. on and on..  guess who ended  up being right on that one..     sure it cost me over $100k to build but.. It was still a pile less than 1/4 the cost of a 'store bought' one..

Thanks again Adam

JFG

[birdhouse]

JFG- don't get me wrong, the powers that will be will decide as to your "fishing" or not.  with my post count in the mere 300+ count, i don't really think my preference will really help your cause.  i feel like i'm taken seriously at times on this website,  but that's why i love this website.  there's NO BS.  there are some VERY intelligent people here, and they're cool with dispelling their thoughts on something that promotes a personal gain, but not so much in the commercial realm.    that's where your problem lies! 

i'd be happy to share with you how "i" think a 100' anemometer tower would be constructed, but i'd bet you'd think it was way over kill.  but that's just how i build stuff. 

you might be better off building this on your own, and hoping it stands. 

i'll keep you posted on what my buddies program tells me, but unsure if it works in canada...   

adam

[Jerryflyguy21]

Thanks Adam, I've found some 3" tubing that is not much more $/ft than the 2" stuff.. so that is probably where I will end up. Maybe w/ the bottom section of the tower from 3" pipe.  I'll re-do my numbers w/ this in mind and just do it if I'm happy with my numbers. That should keep the unhappy posts to a minimum.

Just shoot me a PM if you hear back from your friend

JFG

[fabricator]

It's not so much the size of the tubing as it is the height of the tower along with the size of the pipe, when you are talking 160' that is in the seriously dangerous range, there is a reason commercial towers like this cost $12K.