Rohn Tower advice needed

[letERblow]

Appealing for some help / advice. I have a Rohn  guyed lattice 25G, 70 Ft tower that I want to use with a Dan's style 8 ft wind turbine. My county permitting required I provide engineering design for the tower installation. I hired a PE to review plans and verify the calculations for the tower, guy wire loading and anchors. Rohn installation guidelines were used as a reference for wind loading on the tower itself with additional loading added for the turbine.

The county sent the PE's plans to an independent PE for review.  This is where my problem lies. This engineer brought up the point that the available Rohn information shows the tower is designed for communication equipment that is static (non moving) with nothing indicating that they are designed for dynamic loading required for a wind turbine. To get my permit moving I need to address this PE's concern.

I used this tower 25 years ago on a turbine installation but had to move so it was taken down and stored. I see a lot of references around the net where Rohn towers are being used for turbines.  There are some RE dealers selling the Rohn tower with turbines but say they don't have or not willing to share any design information. Understandable with today's liability issues.

To my question. Does any one have engineering data or installation guidelines on a Rohn  lattice tower for use with a wind turbine or even approved installations that I could show the county that this tower will handle a turbine.
Thanks to all who contribute to this forum, it is an invaluable resource.

[TomW]

Some antennas have rotors. That kind of does not qualify as "static".

Just a thought.

Tom

[tanner0441]

Hi

I used to work on commercial masts, check out the wind loading for something like a 10mtr log periodic antenna as located around some international air ports, or an 8ft Andrews dish. Apart from dynamic vibration from a loaded turbine I think your rotor have no more wind loading than many of the larger Ham radio antennas.

Try antenna manufacturers for the wind loading on their antennas, or even the ARRL antenna handbook....


Brian

[Ungrounded Lightning Rod]

This engineer brought up the point that the available Rohn information shows the tower is designed for communication equipment that is static (non moving) with nothing indicating that they are designed for dynamic loading required for a wind turbine. To get my permit moving I need to address this PE's concern.

What "dynamic loading" is he concerned about?  Can you get him to clarify it?

[defed]

the gyroscopic force maybe?  seems that that is the biggest difference between a mill and an antenna on top of the tower.

[neilho]

If it's any help, Sencenbaugh 12' turbines have been living well on 25Gs for over 30 years with no known structural tower problems. An 8 footer will be even less of a problem, if that's possible. But....that probably doesn't address the PE's specific concern. I'm with ungrounded- if the PE were to articulate and define his concern it would be helpfull. It's clear that this PE is not familiar with wind turbines, so will have to be convinced, bit by bit.

That said, would copies of approved drawings for the Sencenbaugh be usefulll?  I may have some tucked away somewhere.

Neil

[letERblow]

That said, would copies of approved drawings for the Sencenbaugh be usefulll?  I may have some tucked away somewhere.

Neilho

Yes, I think copies of approved installations would be very helpful.  email at don2424 at bridgemail dot com

thanks