Iskra AT5-1 turbine

[Reg Bolger]

Hi everyone,

I am in the process of restoring and installing an old Iskra AT5-1 wind turbine. I'm at a stage now where I need to set the pitch of the blades, Iskra installers use a magnet based setting tool but all I need to know is height from the base of the blade bearing block (face of alternator plate) to the setting point on the trailing edge of the blades. Or the height of the tool.
I would appreciate help or advice from anyone who has knowledge of these older turbines.
Reg

[Andy Rhody]

A bit over my head but would you have any photos? Can you tell us any more about the Iskra? This "Yank" never heard of it.

Here's what I found on the web. Iskra is now owned by "Evance" and manufactured in the UK.

http://evancewind.com/products/r9000-5kw-system/overview

[Reg Bolger]

Hi Andy,

Yes you got it, the Iskra was the forerunner to the Evance R 9000, there is quite a lot of info on the web for both models. The Iskra AT5-1 is the one I am restoring, it's about 6 years old and in quite good condition. There were some minor parts missing (pins, spacers, bolts etc) which I have sorted out now. I am doing a trial assembly of the blade mechanism and need to set the blade pitch angle, I am not sure what this should be. From reading info on turbine blade aerodynamics I think the optimum angle is about 5 deg, the Evance installers use a factory set height gauge, I need to know that height, to prove the 5 deg theory.

Reg

[Rob Beckers]

Reg, welcome to the forum!

Could you post some pictures of the Iskra? I am mightily interested in their pitch-control mechanism. They have a way to pitch the blades to stall/feather when there's no load on the hub (ie. when the grid is down for example). I'd love to learn how that works.

Regarding the blades, I don't have the magic number that they need to be set to. However, looking at various common wind turbine blade profiles, best lift-to-drag looks to be around 8 - 12 degrees, depending on profile. This would be near the blade tip (or 20% in from there, because blade tips tend to be shaped to minimize noise and not aerodynamic efficiency), and this is the apparent angle that the air hits the blade at, so you have to calculate what physical angle this translate to (which in turn depends on the TSR that this rotor should run at, should be in the specs for the turbine).

With a little trigonometry this should get you an angle of the end of the blade vs. the hub/plain-of-rotation, during regular running (the pitch control mechanism on this turbine may have multiple settings, so make sure it's run-angle you're setting). That could be one way to set the blades.

-RoB-

[Reg Bolger]

Hi Bob,

You can find loads of info on the Iskra AT5-1 and the newer Evance R9000 on the the web, there is also an article by Dr Mike Wastling the designer which explains how the mechanism works. It only controls the top speed limiting max RPM to around 220.

Thanks for your info,

Reg

[Hugoo Rdz]

Hi Reg :
I have the same problem. i need also the measure of the hub base to the blade..
do you find the measure ?
i email directly to evance and they have not respond yet.
at this time i have turbine on the pole but is not working at all i think is the pitch set of the blades i hope you can help me thanks