Author Topic: Telescoping flagpole as anemometer mast?  (Read 5923 times)

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Offline d_l

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Telescoping flagpole as anemometer mast?
« on: November 17, 2011, 05:24:36 PM »
I know that a telescoping flagpole has been suggested as an anemometer mast in the past, but has anyone actually used one and what are your opinions? This would be for a VP2 anemometer and not the larger, heavier Vue.

I have a very solid gable mount from my old Digitar days, but due to some spinal problems and landscaping vegetation below it, I probably can't place my 22' A1 ladder to install an anemometer up there without injuring myself.  I guess I could hire out someone to do it or bother a neighbor for help, but often times these installations aren't one-shot deals.  Sometimes they need to be serviced after a failure.

So I've been investigating the possibility of using a telescoping aluminum flagpole as a 20-ft anemometer mast.  My concerns are how much sway might be expected in winds up to 80 mph, how much vibration in those winds can be expected from play in the telescoping segment joints, and would all this affect the wind measurements.  I've looked at video demonstrations of various flagpole's operation with flags on them, but it doesn't seem that they were emphasizing their rigidity in the videos.

Also some poles have a twist and lock mechanism which seems that it would twist the alignment of the anemometer off of north as the pole is raised.  I think the alignment could be twisted back to north by rotating the pole base, but on some poles there is no locking mechanism in the ground sleeve.  This might allow the pole to twist due to wind torque on the anemometer arm.

So I've considered the following for telescoping flagpoles:

Advantages:
  • Relatively easy installation compared to my gable mount
  • Easy to collapse mast for anemometer servicing
  • 20' will be higher than the mast I once had on my gable mount (17')
  • Avoidance of roof top wind turbulence

Disadvantages:
  • Price
  • My limited placement options to avoid blocking my weather cam view or to minimize wind obstructions from trees and other houses
  • Possibility of sway/vibration affecting measurements

Various flagpole dealers are claiming their aluminum poles are stronger than equivalent steel gauges and that their poles can hand 80-90 mph winds with 3x5 flags attached.  This dealer seems to have the best price for what is offered, longest warranty, strongest aluminum, and the thickest pipe gauge of any I've seen: http://tele-pole.com/superior.html 

If I buy a pole and it doesn't work out for an anemometer mast,  I guess could always move it to the front yard to be a flagpole.
« Last Edit: November 17, 2011, 09:01:31 PM by d_l »
--Dave--

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Offline kjf101

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Re: Telescoping flagpole as anemometer mast?
« Reply #1 on: November 18, 2011, 07:40:56 AM »

Offline d_l

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Re: Telescoping flagpole as anemometer mast?
« Reply #2 on: November 18, 2011, 10:04:57 AM »
I am sure it will work, check this out by Rainwise.

Thanks for that link.  It looks like the Rainwise mast has swedged aluminum pipe joints.  I don't know if those pipe joints would be stiffer than telescoping joints and have less sway, but I'd think flying a flag on that mast in high winds wouldn't be feasible though.
--Dave--

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People always talk about the weather, but they never do anything about it.  Not me.  I'm gonna measure it.  www.tceweather.com

Offline PatrioticRick

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Re: Telescoping flagpole as anemometer mast?
« Reply #3 on: January 02, 2012, 06:34:33 AM »
I have had many flag poles in my life and one thing I know is:  In the wind they move! Regardless of if there is a flag on them, because they have no guy wires to stop the movement.  Once I had one of those sectional flag poles with a 3'X5' flag on it and it looked like a fly rod in wind, I took it down and made my own out of 2" schedule 80 pipe 31' tall two peices welded together weighs about 200 lbs and supports a 5'X8' and a 3'X5' flag with no problems, but the pole still moves even with no flags on it, in the wind.     
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Offline d_l

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Re: Telescoping flagpole as anemometer mast?
« Reply #4 on: January 02, 2012, 10:25:13 AM »
So far my experience is that a 25-foot telescoping flagpole made by TelePole, the manufacturer listed above, has shown at most about one foot or so of sway in 45 to +50 mph gusting winds (30-40 mph sustained) with just an anemometer and the standard gold ball on it.  The sway is due to play in the telescoping joints and not from flexing of the individual pipe segments.

As far as I can tell at this time, this degree of sway doesn't seem to appreciably affect the accuracy of wind speed and direction measurements; however, the ball atop the pole might have some influence on the lower wind speed measurements.  This will be watched and tested in the future.

I doubt that most people's generally low opinions on the stiffness and rigidity of telescoping flag poles were formed by observations on the Superior 1 model flag poles manufactured by TelePole.  These poles are the only 10 gauge poles on the market and have only been offered for sale over the last few years.  The more common, cheaper 13-16 gauge poles sold by everyone else would be the poles typically seen flexing in the wind like fly rods.

It should be noted that the 25-foot Superior 1 pole only weighs about 21 pounds which makes it very manageable compared to other heavier mast options suggested here at wxforum.

--Dave--

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Offline Wx4U

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Re: Telescoping flagpole as anemometer mast?
« Reply #5 on: January 02, 2012, 10:22:10 PM »
I'm using a Channelmaster TV antenna telescoping pole. I do have guy wires on it. Probably the max wind it has withstood is around 60 mph. No problems. I have a 4"X4"X6' post in the ground, then clamped the telescoping pole to it. It can be turned to set the correct direction. Guess it has been up over two years. Make sure you add a good ground.
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Offline WeatherHost

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Re: Telescoping flagpole as anemometer mast?
« Reply #6 on: January 03, 2012, 09:46:01 AM »
made my own out of 2" schedule 80 pipe 31' tall two peices welded together weighs about 200 lbs

How did you raise that to vertical?  We had a discussion about that on another thread not too long ago.

Offline Skywatch

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Re: Telescoping flagpole as anemometer mast?
« Reply #7 on: January 03, 2012, 12:47:12 PM »
My pole is made from galvanized steel and stands at 25 Ft it does sway about 6 inches in moderate wind conditions (10-15 mph) but doesn't rock untill we hit 40mph and we hardly ever see anything over 50mph. But I would gess it would be about 60mph before we see any damage to the pole. I have the pole lashed at 10 ft above that it's on it's own.

When fully extended how much pipe is left unextended or inside the lower pole section? I would think the closer you have the 2 ends together the more instable it would be.
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Offline PatrioticRick

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Re: Telescoping flagpole as anemometer mast?
« Reply #8 on: January 05, 2012, 12:16:13 AM »
made my own out of 2" schedule 80 pipe 31' tall two pieces welded together weighs about 200 lbs

How did you raise that to vertical?  We had a discussion about that on another thread not too long ago.

Three ropes, one tied to my truck to lift it and the other two held by myself and a neighbor to guide it up and into a socket, as the truck backed up slowly it raised, once vertical dropped in a socket with a little help from my daughter making sure it didn't slide.  Took two trys first time fell to one side into a tree.  OK so I'm not an artist, but here it is.  :oops:

 
Flagpole0001 by PatrioticRick, on Flickr


Garfield Area looking East to 3700E by PatrioticRick, on Flickr

Ben up for about eight years now.
« Last Edit: January 06, 2012, 04:25:15 AM by PatrioticRick »
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WU=KIDRIGBY2
PWS=RIGBYWX1
WxBug=p19372
WOW=373047692

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Offline wuhu_software

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Re: Telescoping flagpole as anemometer mast?
« Reply #9 on: January 20, 2012, 05:03:47 PM »

Harbor Freight sells a couple of them pretty cheap.

http://www.harborfreight.com/catalogsearch/result?q=telescoping+flag+pole

I will probably give one a try as I cannot access the roof top during the winter months.

Offline d_l

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Re: Telescoping flagpole as anemometer mast?
« Reply #10 on: January 20, 2012, 06:32:12 PM »
I wouldn't advise getting a flag pole thinner than 10 gauge if you have winds higher than 40 mph.  Even a 10 gauge pole flexes a bit in those winds, but I'd be afraid of a thinner walled pole possibly folding over in +40-50 mph winds.
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Offline wuhu_software

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Re: Telescoping flagpole as anemometer mast?
« Reply #11 on: January 21, 2012, 09:53:15 AM »

Since these poles are not holding a flag, I think 40+ mph speeds should not be an issue. If it is affixed to a house, you also devise a scheme using a bracket or wires to stabilize the pole so that the flex is minimized to the last section or two.

Offline WeatherHost

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Re: Telescoping flagpole as anemometer mast?
« Reply #12 on: January 21, 2012, 10:08:42 AM »
I wouldn't advise getting a flag pole thinner than 10 gauge if you have winds higher than 40 mph.  Even a 10 gauge pole flexes a bit in those winds, but I'd be afraid of a thinner walled pole possibly folding over in +40-50 mph winds.

I've got two pieces of 3/4" conduit strapped to a 17G fence top rail (effectively 3 small masts lashed together to make one multi-core mast) and it would flop around like a dead herring if it wasn't guyed and attached to the back of the garage.  But at least I can lower and raise it without too much trouble.


Offline d_l

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Re: Telescoping flagpole as anemometer mast?
« Reply #13 on: June 07, 2012, 02:18:46 PM »
As a follow up to this thread, I installed a Davis 6382 Temp/Hum station and connected it to the Davis anemometer transmitter with 25 feet of 6 wire phone cable to make a partial ISS.  I thought that the radiation shield of the 6382 might cause excessive sway in high winds so I guy wired the flagpole.  A bit of my 12-foot high anemometer can be seen on the extreme left of the photo.  Since I added the temp/hum sensor and guy wires, it has registered a 64 mph peak gust.
--Dave--

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Offline tsharac

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Re: Telescoping flagpole as anemometer mast?
« Reply #14 on: June 08, 2012, 09:10:33 AM »
Looks great!

What gauge guy wires did you use? How far away from the mast are the guy wires anchored?

Offline d_l

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Re: Telescoping flagpole as anemometer mast?
« Reply #15 on: June 08, 2012, 10:55:42 AM »
What gauge guy wires did you use? How far away from the mast are the guy wires anchored?

I felt this particular pole's pipes at 10 gauge could handle the wind load unassisted if necessary, but that the constant flexing play in the sliding joints could wear them over time.  So I used 1/8" clear coated, guy wires to steady it.  I think I could easily have dropped that to 3/32" and still had enough strength in the wires.  The load strength of the wires was rated at about 90 lbs., but I thought that I might have to make several trial-and-error attempts at setting the clamps and thimble hardware on each line to be within the turnbuckle's tightening range.  I was right. So each wire has several pinch spots from incorrect clamping attempts that reduce its load strength.  Really, a lot of my choice in wire size was determined by the size of clamps and turnbuckles the hardware store had available.

The three wires aren't exactly at a 120 degree separation angle around the pole, but were placed to minimize the likelihood that they would be a path obstruction in the natural vegetation behind the wall. They also are oriented to cover the strongest wind directions.  The wires are about 30-33' long attached to construction stakes driven into the ground.  The ground is quite rocky back there so finding a place to drive them in was more important than the exact distance (roughly 15-16') from the pole base.  The attachment angles at the top and bottom are therefore very roughly around 30 and 60 degrees respectively.

The top wire thimbles are hooked to several of the flagpole's carabiners which are then hooked to the top rotating swivel hardware normally used for a flag.  The manufacturer claims that this hardware is made of carbon fiber so it should be a strong enough and durable attachment point.

I think a cheaper model flagpole with thinner gauge walls could be used like this as long as dependably strong guy wires were attached to it.  Although the Lexan flag swivels of the cheaper poles might not hold up well as an attachment point over time.
--Dave--

Wireless VP2 w/ solar, 24hr FARS, Heater, (Envoy-WLIP)*2-Meteohub, plus custom VP2 @ 26', WL 6.0.0, WU & W4U=KNVRENO37 NetcamXL

People always talk about the weather, but they never do anything about it.  Not me.  I'm gonna measure it.  www.tceweather.com

 

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