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Dec 01, 2021, 05:56 AM
Tragic case
davidleitch's Avatar
Thread OP
Discussion

What's the wind speed where you fly?


These days I spend a lot of time thinking about renewable energy including wind. Because I am not getting anywhere on a particular project I procrastinated and decided to look up the wind speeds of some of the glider sites I have flown at in Australia. Actually in the list below I haven't flown at Dalby.

These days very good wind data is freely available down to a resolution of 1 km and at a height of 100 metres. Us model plane flyers generally measure at lower height but are often flying at round 100 metres.

The data is year round and on a 24 hour basis. Other data available to me (wind farm output by time of day) suggests that wind speeds in the middle of the day might be 5-10% less than the overall averages.

Still when we add in thermal impacts iI think its consistent with a view that in Australia we need "storm" or at a minimum "standard" models.

Still I'd be interested in any comparative data from other countries.
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Dec 01, 2021, 08:13 AM
Screwing up is an art
mabrungard's Avatar
In the US, I use https://www.ryancarlton.com/ and https://www.windy.com/
Dec 01, 2021, 02:49 PM
VHO
VHO
glider misguider
Hi David,

A good start, can we have some measure of variation as well, standard deviation would be useful.

Hutton from windy Armidale...
Dec 01, 2021, 03:31 PM
DS Junkie
Screamin' Eagle's Avatar
Not sure how to characterize wind speeds around here but absolutely calm days almost never happen. We usually get either afternoon onshores at 15 mph or so, or offshore winds that can be 10 mph up to 60 mph. All that said, I opt for strong/windy layups in all my thermal ships too. I don't fly contests is probably why.
Dec 02, 2021, 01:10 AM
Hugh Blackburn
floquet's Avatar
It almost always seems windy where we fly (at Diggers Rest near Melbourne). But still, I own a light plane… I remember seeing pretty crude isopleth maps - of mean wind speeds - for Australia (dating from the 1970s) which showed the southern edges of Australia were pretty windy on average. Where should I look to find the windspeed data you’re alluding to?

Nice flying with you!
Dec 02, 2021, 03:50 AM
Registered User
Tuomo's Avatar
FAI limit is 12m/s constant

As stated, perfectly calm days almost never happen, or it is only a momentary condition between thermals. We have been looking for late evening and early morning flying, but it seems that there is almost always some activity in air.

12m/s constant wind also almost never happens. More typical very windy day is 8-10m/s constant with gusts to 14-15m/s. Flying in this kind of weather is pain because landing out is a real risk when gets caught in sinking air when downwind.

Recently we have paid more attention to density altitude. Flying in Finland is generally easy since we rarely need to fly in really high density altitude conditions, though in summer it occasionally happens. Density altitude is not that much discussed but it definitely affects trim and ballasting.

PS davidleitch posted statistics with about 6m/s wind speeds. But it was in 100m altitude. Typically wind gradient is such that 6m/s at higher altitude must be 4m/s or less at few meters altitude the FAI measurement is made. Anyways 4-6m/s is typical nice F5J weather. It is also a wind speed where almost all F5J lay ups work fine. The very light ones can be ballasted accordingly, and heavy lay ups are in their comfort zone.
Last edited by Tuomo; Dec 02, 2021 at 04:03 AM.
Dec 02, 2021, 04:42 AM
Tragic case
davidleitch's Avatar
Thread OP
Quote:
Originally Posted by floquet
It almost always seems windy where we fly (at Diggers Rest near Melbourne). But still, I own a light plane… I remember seeing pretty crude isopleth maps - of mean wind speeds - for Australia (dating from the 1970s) which showed the southern edges of Australia were pretty windy on average. Where should I look to find the windspeed data you’re alluding to?

Nice flying with you!
Hugh

Likewise a pleasure flying with you. That Ned Kelly cup was one of the most fun things I've done in the past couple of years. We had no right to such good weather and excellent thermals and good company.

https://www.nationalmap.gov.au

Explore map data/energy/renewable energy/wind Resolution is to 1 km, at least for the NSW section.
Dec 02, 2021, 04:44 AM
Tragic case
davidleitch's Avatar
Thread OP
Quote:
Originally Posted by Tuomo
FAI limit is 12m/s constant

As stated, perfectly calm days almost never happen, or it is only a momentary condition between thermals. We have been looking for late evening and early morning flying, but it seems that there is almost always some activity in air.

12m/s constant wind also almost never happens. More typical very windy day is 8-10m/s constant with gusts to 14-15m/s. Flying in this kind of weather is pain because landing out is a real risk when gets caught in sinking air when downwind.

Recently we have paid more attention to density altitude. Flying in Finland is generally easy since we rarely need to fly in really high density altitude conditions, though in summer it occasionally happens. Density altitude is not that much discussed but it definitely affects trim and ballasting.

PS davidleitch posted statistics with about 6m/s wind speeds. But it was in 100m altitude. Typically wind gradient is such that 6m/s at higher altitude must be 4m/s or less at few meters altitude the FAI measurement is made. Anyways 4-6m/s is typical nice F5J weather. It is also a wind speed where almost all F5J lay ups work fine. The very light ones can be ballasted accordingly, and heavy lay ups are in their comfort zone.
Density is an issue in Australia, I think. Although I'm not sure :-)
Dec 02, 2021, 05:04 AM
Tragic case
davidleitch's Avatar
Thread OP
Quote:
Originally Posted by VHO
Hi David,

A good start, can we have some measure of variation as well, standard deviation would be useful.

Hutton from windy Armidale...
Hutton the data set available to me does not directly let me see standard deviation, and I'm not sure wind is normally distributed. I did convert the sapphire wind farm (at glen innes) output as a proxy index of wind speed, but then I remembered that the relationship between wind farm output and wind speed is cubical. I'll have a go at it again tomorrow evening.
Last edited by davidleitch; Dec 02, 2021 at 05:21 AM.
Dec 02, 2021, 05:08 AM
Tragic case
davidleitch's Avatar
Thread OP
So although its a long way from finding out what the wind speed is at other flying fields around the world. I had a go at Huttons question for Armidale. The Armidale mean wind speed at 100 metres year over a year is 7.2 m/s. I don't have access to the standard deviation etc but...

I do have access to a near enough wind farm Sapphire where I can get the half hourly output in MW. Lets use the past two years. Using a pivot table I can get the overall average but also the average by time of day and month of year.

Wind farm output goes up with the cube of the wind speed change, so adjusting for that and assuming that change in wind speed is the only thing leading to a change in wind farm output I get the graph below. I have all 12 months but just selected 4 including January for the australia day comp.

You get the well known in the industry, but less so in the wider world impact that wind output is relatively low in the middle of the day compared to nights. However there may also be a small artefact of the wind farm restricting output due to negative prices in the middle of the day, but I don't think that applies in this particular case.

Thinking about temperature as well, the data suggests that April would be a good time to hold a comp in Eastern Australia.
Last edited by davidleitch; Dec 02, 2021 at 07:06 AM.
Dec 02, 2021, 01:41 PM
Registered User
Tuomo's Avatar
Quote:
Originally Posted by davidleitch
Density is an issue in Australia, I think. Although I'm not sure :-)
Down under everything is more dense?

For us the statistically most windy season is winter. I do not care since then it is anyways mostly too cold to fly. In summer we mostly have typical continental weather. At least when low pressure areas from Atlantic, or cold burst from north pole, is not rolling over. It happens

Theoretically climate change should increase average (and peak) wind speeds. For us it can be observed in a different way. The warm summer - and best flying weather - is now much longer than it used to be 20-25 years ago. Also the time when we have snow or lakes covered with ice is shorter.
Dec 02, 2021, 02:50 PM
VHO
VHO
glider misguider
Quote:
Originally Posted by davidleitch
So although its a long way from finding out what the wind speed is at other flying fields around the world. I had a go at Huttons question for Armidale. The Armidale mean wind speed at 100 metres year over a year is 7.2 m/s. I don't have access to the standard deviation etc but...

I do have access to a near enough wind farm Sapphire where I can get the half hourly output in MW. Lets use the past two years. Using a pivot table I can get the overall average but also the average by time of day and month of year.

Wind farm output goes up with the cube of the wind speed change, so adjusting for that and assuming that change in wind speed is the only thing leading to a change in wind farm output I get the graph below. I have all 12 months but just selected 4 including January for the australia day comp.

You get the well known in the industry, but less so in the wider world impact that wind output is relatively low in the middle of the day compared to nights. However there may also be a small artefact of the wind farm restricting output due to negative prices in the middle of the day, but I don't think that applies in this particular case.

Thinking about temperature as well, the data suggests that April would be a good time to hold a comp in Eastern Australia.
Thanks David,

I realised after I asked that its a difficult problem getting errors for wind speed because the residuals would not be normally distributed (lower bound 0 upper ?) hence standard deviation isn't appropriate.

Your data retrieval is useful and matches experience here.

Not sure there is an appetite to move our Sailplane event from January to April despite summer storms interrupting at times.

Hutton
Last edited by VHO; Dec 02, 2021 at 07:57 PM. Reason: corrected
Dec 03, 2021, 05:24 PM
Hugh Blackburn
floquet's Avatar
Quote:
Originally Posted by floquet
It almost always seems windy where we fly (at Diggers Rest near Melbourne).
Where the average wind speed at 100m is 8.0m/s. So I'm right to think it's rather more windy than the places in the OP's table: this agrees with our general perception that it usually seems windy - and cold!
Dec 04, 2021, 06:33 PM
Everything’s A Compromise
Larrikin's Avatar
Quote:
Originally Posted by VHO
T
Not sure there is an appetite to move our Sailplane event from January to April despite summer storms interrupting at times.
Hutton
No objection here.
Late March perhaps so that it doesn't clash with Easter events.
Too hard given that the public holiday is utilised in January.
Last edited by Larrikin; Dec 04, 2021 at 06:40 PM.


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