Air-X wind generator: Blade modification?

sebastiannr

sebastiannr

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Hi there,

My Air-X is so noisy that I just don't use it.

How I would love some Spreco replacement blades, but at £280 it just seems too expensive.

I saw a post from a few years ago, where someone said 'after doing some work on the blades, I have no noise issues at all'. They didn't elaborate on what this 'work' was, so I'm wondering if anyone else has modified the blades to reduce noise levels.

If you have, please let me know what you did!

P.S. I have lightly sanded the edges and polished the blades up somewhat, but with no improvement on noise levels.
 
sebastiannr said:
Hi there,

My Air-X is so noisy that I just don't use it.

How I would love some Spreco replacement blades, but at £280 it just seems too expensive.

I saw a post from a few years ago, where someone said 'after doing some work on the blades, I have no noise issues at all'. They didn't elaborate on what this 'work' was, so I'm wondering if anyone else has modified the blades to reduce noise levels.

If you have, please let me know what you did!

P.S. I have lightly sanded the edges and polished the blades up somewhat, but with no improvement on noise levels.
Click to expand...

Are you sure they weren't modifying a neighbors blades by throwing some rope into them? That'd keep the noise down and always seems a popular response on here to windmills.

On a more serious note, are you able to explain how the noise is generated? Is it vibration based or whistling through the air, or a tearing noise? You may not find someone here who has done it but there are plenty clever enough to make suggestions with sufficient details.
 
Various mods have been suggested. Smoothing would help. the blades on mine area rough and ready. I have also been told that shortening baled tenth helps. Tip speed etc. My main concern is getting the blades out of balance which would be a problem at the high speed they run at.

The Spreco sound quite in harbour, please try a set and tell me how good they are at sea, before is splash out £280
 
lustyd said:
Are you sure they weren't modifying a neighbors blades by throwing some rope into them? That'd keep the noise down and always seems a popular response on here to windmills.

On a more serious note, are you able to explain how the noise is generated? Is it vibration based or whistling through the air, or a tearing noise? You may not find someone here who has done it but there are plenty clever enough to make suggestions with sufficient details.
Click to expand...

The vibration isn't bad, it's the whistling and tearing noises that are the real killers.

There are two boats here (Arrecife, Lanzarote) that have totally silent wind mills... Jealousy is a terrible thing...
 
sebastiannr said:
The vibration isn't bad, it's the whistling and tearing noises that are the real killers.

There are two boats here (Arrecife, Lanzarote) that have totally silent wind mills... Jealousy is a terrible thing...
Click to expand...

I can't believe you bought a wind generator without first wandering around a marina listening to different types!
 
sebastiannr said:
My Air-X is so noisy that I just don't use it.

I saw a post from a few years ago, where someone said 'after doing some work on the blades, I have no noise issues at all'. They didn't elaborate on what this 'work' was, so I'm wondering if anyone else has modified the blades to reduce noise levels.
If you have, please let me know what you did!
P.S. I have lightly sanded the edges and polished the blades up somewhat, but with no improvement on noise levels.
Click to expand...

My 10 year-old Air-X does not suffer from such noise - well, it does whistle a bit in high winds but it is not unbearable. I did smooth all casting blips and edges, which helped but nothing dramatic. I do think at some point through the production years the manufacturer did address the problem as there does seem to be some less noisy examples.

I understand that the really intrusive noise comes from tip flutter as the blades are aerodynamically shaped that draws out the tips to a very thin profile that is not stiff enough to resist bending in stronger winds. I think shortening to an extent where the ends are thicker would be worth doing if the noise is as bad as you say. A sensitive balance would ensure there need be no weight difference between blades.

The great advantage I found was when I had sufficient wind for sailing, was that the Air-X, with its substantial output, could supply all the Amps needed for refrigerator, computer, autopilot and instruments. However, the problem of being at anchor without wind led me to fit solar panels and so I rarely have to switch on the Air-X these days. With the 'Stop' switch enabled the blades just slowly and silently windmill in any force of wind.
 
Barnac1e said:
My 10 year-old Air-X does not suffer from such noise - well, it does whistle a bit in high winds but it is not unbearable. I did smooth all casting blips and edges, which helped but nothing dramatic. I do think at some point through the production years the manufacturer did address the problem as there does seem to be some less noisy examples.

I understand that the really intrusive noise comes from tip flutter as the blades are aerodynamically shaped that draws out the tips to a very thin profile that is not stiff enough to resist bending in stronger winds. I think shortening to an extent where the ends are thicker would be worth doing if the noise is as bad as you say. A sensitive balance would ensure there need be no weight difference between blades.

The great advantage I found was when I had sufficient wind for sailing, was that the Air-X, with its substantial output, could supply all the Amps needed for refrigerator, computer, autopilot and instruments. However, the problem of being at anchor without wind led me to fit solar panels and so I rarely have to switch on the Air-X these days. With the 'Stop' switch enabled the blades just slowly and silently windmill in any force of wind.
Click to expand...

Thanks for the info. I think I will try shortening the blades, though it's strange that my unit seems to make more noise than others (I don't think anyone would accept the noise levels of my one, people on other boats have commented on how noisy it is (embarrassing!)).

On another note, you say that the unit can provide enough power for fridge etc. I also have 2 x 80W solar panels, and the Air-X doesn't even come close to generating as much power as they do, even here where there are constant trade winds. It generally puts out 1-2 amps in say, 10-15 knots of wind, and up to 5 amps when it blows more. Does that mean there is a fault with it? And if so, what could it be? Old wiring perhaps... or maybe faulty electronics within the unit?
 
sebastiannr said:
Thanks for the info. I think I will try shortening the blades, though it's strange that my unit seems to make more noise than others (I don't think anyone would accept the noise levels of my one, people on other boats have commented on how noisy it is (embarrassing!)).

On another note, you say that the unit can provide enough power for fridge etc. I also have 2 x 80W solar panels, and the Air-X doesn't even come close to generating as much power as they do, even here where there are constant trade winds. It generally puts out 1-2 amps in say, 10-15 knots of wind, and up to 5 amps when it blows more. Does that mean there is a fault with it? And if so, what could it be? Old wiring perhaps... or maybe faulty electronics within the unit?
Click to expand...
With mine I see the Amps via a dedicated meter and the output is dependent on the battery state - with full batteries the charge is always low. In comparison, two years ago when I had old, end-of-life batteries and anchored in 25 knots of wind, 43 Amps were pouring out of the Air-X. Certainly under sail my power demands are modest, probably 6A-8A even when the refrigerator kicks in - my 31', 7 ton motor sailor needs a good breeze to tramp along, so I don't have a problem.

I don't know how accurate the following graph is and it is anyway difficult to interpolate the scales, but your 400W Air-X should do better than 2X80W panels when there is wind ... especially during non-daylight hours :D


chart
 
Thanks again for the detailed information.

you're right, that would explain why I'm not seeing that much output from the Air-x - when I've turned it off and on to check the output it's generally been either during the day when the panels are also providing power, or in the evening, when the batteries are near to full capacity from having a day's worth of sunlight.

I think I'm going to buy the SilentPower blades, I love wind power and I hate not being able to just keep the thing going 24/7 due to the noise.
 
sebastiannr said:
From about 4.15 on this video I think gives some kind of idea of the noise, but of course it's worse in reality. Is this more noise than the average Air-X?
http://www.youtube.com/watch?v=e5YT9z8-R-w
Click to expand...
Difficult to judge - much less than the wind-microphone noise. Fairly standard I would think.

Perhaps you are particularly sensitive or perhaps all we Air-X owners are psychologically and subjectively influenced by the thought of all that lovely power being generated and brain-washed into not hearing the downside of noise.

Even so, the mast comes in useful ... Anchor light and AIS antenna share the pole.

If you do upgrade the blades then please post your impressions.
 
I profiled a spare set of blades to look a bit like the Spreco blades, made sure they were all modified exactly the same, not much difference in noise levels.

Spreco blades ordered, will post impressions after they're installed.
 
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