Gather local wind data

[Anders Petersson]

Hi
I have developed a system "Windsond" to gather local wind data at different altitudes in an easy way. This is done by launching a 60 liter helium balloon with electronics that transmits back sensor data as it ascends. On the ground, a laptop receives the data and displays diagrams of wind speed, direction and temperature.

The idea is not new, and weather balloons are indeed launched daily all over the world. The novel thing is the light weight and low cost, for a system adapted for altitudes up to 3000m. We use this for hot air balloons where we also recover the electronics again with a success rate around 80%.
More information and pictures here: http://kiwiembedded.com/windsond/

From discussing with a glider pilot, it seems this could be interesting for your sport as well. But you also want humidity readings, right? I'm interested in your comments and what potential you see. Looking forward to hear from you either here or on email .

Thanks for your time,
/Anders Petersson
Embedded systems designer

[Tony[_5_]]

On Friday, September 14, 2012 8:12:25 AM UTC-5, Anders Petersson wrote:
> Hi I have developed a system "Windsond" to gather local wind data at different altitudes in an easy way. This is done by launching a 60 liter helium balloon with electronics that transmits back sensor data as it ascends. On the ground, a laptop receives the data and displays diagrams of wind speed, direction and temperature. The idea is not new, and weather balloons are indeed launched daily all over the world. The novel thing is the light weight and low cost, for a system adapted for altitudes up to 3000m. We use this for hot air balloons where we also recover the electronics again with a success rate around 80%. More information and pictures here: http://kiwiembedded.com/windsond/ From discussing with a glider pilot, it seems this could be interesting for your sport as well. But you also want humidity readings, right? I'm interested in your comments and what potential you see. Looking forward to hear from you either here or on email . Thanks for your time, /Anders Petersson Embedded systems designer

Temp and dew point readings would be most important. what is the approximate cost for each unit? I could definitely see this being used during contests to get a local real life sounding instead of depending on computer model forecasts. If cheap enough it potentially could be used for every weekend club operations too.

[[email protected]]

On Friday, September 14, 2012 9:29:31 AM UTC-4, Tony wrote:
> On Friday, September 14, 2012 8:12:25 AM UTC-5, Anders Petersson wrote:
>
> > Hi I have developed a system "Windsond" to gather local wind data at different altitudes in an easy way. This is done by launching a 60 liter helium balloon with electronics that transmits back sensor data as it ascends. On the ground, a laptop receives the data and displays diagrams of wind speed, direction and temperature. The idea is not new, and weather balloons are indeed launched daily all over the world. The novel thing is the light weight and low cost, for a system adapted for altitudes up to 3000m. We use this for hot air balloons where we also recover the electronics again with a success rate around 80%. More information and pictures here: http://kiwiembedded.com/windsond/ From discussing with a glider pilot, it seems this could be interesting for your sport as well. But you also want humidity readings, right? I'm interested in your comments and what potential you see. Looking forward to hear from you either here or on email . Thanks for your time, /Anders Petersson Embedded systems designer
>
>
>
> Temp and dew point readings would be most important. what is the approximate cost for each unit? I could definitely see this being used during contests to get a local real life sounding instead of depending on computer model forecasts. If cheap enough it potentially could be used for every weekend club operations too.

I agree. A higher release altitude is needed -- minimum 2km for US East Coast
or Europe; as much as 6000m in the West where only airspace is the limit.
In the EDT time zone (UTC -4) the weather service data isn't available until
9am, which isn't long before the usual pilot meeting. Weather briefers
are stuck using model data based on measurements taken 10 hours earlier,
and checking at the last minute a measurement taken 100s of km away.
I don't know much about balloon parameters so I can't say exactly what this
will do to the sonde capabilities needed.

I could see this as being useful for wave camp, in which case a 7000m altitude
would be needed, plus a long slant range because the wind velocities would be
higher (>100km/hr is typical for a wave day). However, that's an extreme case.
For wave flights we like to launch early in the day before convection starts,
so, again, we depend on stale measurements taken a long ways away.

-- Matt

[Anders Petersson]

Thank you for your comments!

I have used Windsond up to 2.5km altitude. The current solution can do higher but I haven't checked exactly how high. I understand you want as high as possible but at some point the increased technical demands starts affecting the price of a sounding. If there's much interest in this I'll look more into it and give a better answer.

I'm aiming for a price point under $150 per unit. The exchange rate is unfavorable for USD at the moment.

[Steve Leonard[_2_]]

My biggest interest is in temperature versus altitude in the first 1KM to 1..5KM above the surface. This will let you know where the cap that might kill the day exists. I had started a project for this some years ago, and since the wind usually blows here in Kansas, I was looking to use a couple of kites to lift the package. It would always stay within the confines of the airport, and would have much lower recurring cost than a helium balloon. I would be intereted in a package that gets temperature and altitude either logged on board, or transmitted to a PC on the ground. And at $150 or so, I am very interested.

Steve Leonard

[Eric Greenwell[_4_]]

On 9/20/2012 9:25 AM, Steve Leonard wrote:
> My biggest interest is in temperature versus altitude in the first
> 1KM to 1.5KM above the surface. This will let you know where the cap
> that might kill the day exists. I had started a project for this
> some years ago, and since the wind usually blows here in Kansas, I
> was looking to use a couple of kites to lift the package. It would
> always stay within the confines of the airport, and would have much
> lower recurring cost than a helium balloon. I would be intereted in
> a package that gets temperature and altitude either logged on board,
> or transmitted to a PC on the ground. And at $150 or so, I am very
> interested.

Have you found the NWS lapse rate forecasts inadequate?

http://rucsoundings.noaa.gov/

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Tony[_5_]]

On Thursday, September 20, 2012 7:35:02 PM UTC-5, Eric Greenwell wrote:
> On 9/20/2012 9:25 AM, Steve Leonard wrote: > My biggest interest is in temperature versus altitude in the first > 1KM to 1.5KM above the surface. This will let you know where the cap > that might kill the day exists. I had started a project for this > some years ago, and since the wind usually blows here in Kansas, I > was looking to use a couple of kites to lift the package. It would > always stay within the confines of the airport, and would have much > lower recurring cost than a helium balloon. I would be intereted in > a package that gets temperature and altitude either logged on board, > or transmitted to a PC on the ground. And at $150 or so, I am very > interested. Have you found the NWS lapse rate forecasts inadequate? http://rucsoundings.noaa.gov/ -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)

Usually the soundings there are pretty good but we've also gone through spells where we had inversions that the models just weren't catching. Sometimes this has gone on for weeks, like for 2 or 3 weeks last June when the models were all predicting great soaring when in fact there was a hard inversion at about 5000 MSL and it totally sucked.

I think there is some real benefit to having actual measured real life data instead of a computer model. At 150 per unit, especially if you can reliably retrieve the transmitter, I think it would be worth it.

[Eric Greenwell[_4_]]

On 9/21/2012 2:22 PM, Tony wrote:
> On Thursday, September 20, 2012 7:35:02 PM UTC-5, Eric Greenwell
>> Have you found the NWS lapse rate forecasts
>> inadequate? http://rucsoundings.noaa.gov/ -- Eric Greenwell -
>> Washington State, USA (change ".netto" to ".us" to email me)
>
> Usually the soundings there are pretty good but we've also gone
> through spells where we had inversions that the models just weren't
> catching. Sometimes this has gone on for weeks, like for 2 or 3 weeks
> last June when the models were all predicting great soaring when in
> fact there was a hard inversion at about 5000 MSL and it totally
> sucked.
>
> I think there is some real benefit to having actual measured real
> life data instead of a computer model. At 150 per unit, especially if
> you can reliably retrieve the transmitter, I think it would be worth
> it.

Maybe you could talk an ultralight pilot into doing it for the gas
money. They like to fly in the morning anyway, and having a mission
would delight the ones I know. There are $60-$100 USB temperature and
humidity recorders that could easily carried (a few oz.), downloaded to
a PC after landing, then the file emailed to you.

Here are some examples:

http://www.thermoworks.com/products/logger/usb_loggers.html

The trick is selecting one with a proper response time to get an OK
lapse rate. The one I have is about a minute - too slow for a climbing
aircraft measurement - but I saw one of 20 seconds (probably OK for a
500fpm climb rate). That would give a decent lapse rate.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Papa3[_2_]]

On Friday, September 21, 2012 6:11:53 PM UTC-4, Eric Greenwell wrote:
> There are $60-$100 USB temperature and
>
> humidity recorders that could easily carried (a few oz.), downloaded to
>
> a PC after landing, then the file emailed to you.
>
>
>
> Here are some examples:
>
>
>
> http://www.thermoworks.com/products/logger/usb_loggers.html
>
>
>
> The trick is selecting one with a proper response time to get an OK
>
> lapse rate. The one I have is about a minute - too slow for a climbing
>
> aircraft measurement - but I saw one of 20 seconds (probably OK for a
>
> 500fpm climb rate). That would give a decent lapse rate.
>
>
>
> --
>
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
>
> email me)

Interesting. Aside from the morning sounding, it would be very interesting to gather data for after-the-fact comparison of model forecast sounding vs.. actual. These don't look perfect (the accuracy is a little coarser than I'd like), but I could see fixing one of these under the wing of our club Grob and doing some interesting studies. My suspicion is that many of the misses where we are (NJ/PA area) have less to do with the basic atmospheric lapse rate and more to do with getting the surface dewpoints and amount of surface heating wrong, but this would be a good way to test that out.

[Steve Leonard[_2_]]

As Tony said, we can have really inacurate forecasts here. Mainly because our closest sounding sites are either the other side of the Marfa Dry Line, far enough upwind that even though there are no obvious airmass boundaries, the airmass is definitely different (look at OLC posts from Hinton, OK versus Sunflower on 7-20-2012), or far downwind into the armpit of the soaring world (Topeka, KS). A local sounding is really needed to know what might happen.

As for hiring an ultralight, that would probably cost at least as much each time as a helium balloon. And remember. We are in Kansas. The reason I was thinking of using kites is because the wind blows. Lots. And many days, the ultralight pilot will either not be available or willing to go. I have a couple of hundred dollars worth of kites and high strength line. Now, I just need a small data package to put onboard!

Those are neat loggers, but I didn't see one that measures pressure (altitude). Without that, you have nothing. What we are really looking for is "will it go to at least 3000?" The day's Tony mentioned were 5000 MSL, or 3500 AGL. With a saounding to even 3000, we would know what we would be up against.

I sense the technology is available now, but maybe just not for a mass market. Hoping Andres is still watching this thread.

Steve

[Eric Greenwell[_4_]]

On 9/23/2012 7:43 PM, Steve Leonard wrote:
> As Tony said, we can have really inacurate forecasts here. Mainly
> because our closest sounding sites are either the other side of the
> Marfa Dry Line, far enough upwind that even though there are no
> obvious airmass boundaries, the airmass is definitely different (look
> at OLC posts from Hinton, OK versus Sunflower on 7-20-2012), or far
> downwind into the armpit of the soaring world (Topeka, KS). A local
> sounding is really needed to know what might happen.
>
> As for hiring an ultralight, that would probably cost at least as
> much each time as a helium balloon. And remember. We are in Kansas.
> The reason I was thinking of using kites is because the wind blows.
> Lots. And many days, the ultralight pilot will either not be
> available or willing to go. I have a couple of hundred dollars worth
> of kites and high strength line. Now, I just need a small data
> package to put onboard!
>
> Those are neat loggers, but I didn't see one that measures pressure
> (altitude). Without that, you have nothing. What we are really
> looking for is "will it go to at least 3000?" The day's Tony
> mentioned were 5000 MSL, or 3500 AGL. With a saounding to even 3000,
> we would know what we would be up against.

Here's one that's not as convenient, perhaps, but does measure altitude
and temperature, plus GPS and more if you want it.

$70 logger
$38 20k altimeter sensor
$11 temperature sensor
http://www.eagletreesystems.com/MicroPower/micro.htm

The model rocket people have this kind of stuff, and a 3000 agl rocket
might be a cheap and reliable way to put the instruments up where you
want them. Retrieving in a wind would involve a chase, but they also
have locators of various types to help find it. There is likely a model
rocket society somewhere near you that could help.

Here is a rocket logger: altitude, temperature - $80

http://www.perfectflite.com/sl100.html

It has two chute deployment altitudes - small chute at the top of the
launch, bigger one near the ground, so drift is minimized.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Steve Leonard[_2_]]

On Monday, September 24, 2012 12:10:39 AM UTC-5, Eric Greenwell wrote:

Here is a rocket logger: altitude, temperature - $80 http://www.perfectflite.com/sl100.html

May have to get one of those. But again rockets are not the way to go for recurring cost. As I recall from talking with one of our local rocket guys, they are $30 and up per shot. Don't mind a few more bucks to get started, but hate recurring costs.

Thanks for the searching, Eric. If I get one, I will let you know how the kite flying and data collecting goes. That one might have issues, as the launch, climb, and recovery of the kite will likely be more than 9 minutes. Reeling in 7000 feet of like takes a bit of time!

Steve

[Dan Marotta]

Steve,

Would XCSkies work for your needs? I see, looking at the map for
Hutchinson, that you should be getting lift up to 2,000' AGL right now!


"Steve Leonard" > wrote in message
...
On Monday, September 24, 2012 12:10:39 AM UTC-5, Eric Greenwell wrote:

Here is a rocket logger: altitude, temperature - $80
http://www.perfectflite.com/sl100.html

May have to get one of those. But again rockets are not the way to go for
recurring cost. As I recall from talking with one of our local rocket guys,
they are $30 and up per shot. Don't mind a few more bucks to get started,
but hate recurring costs.

Thanks for the searching, Eric. If I get one, I will let you know how the
kite flying and data collecting goes. That one might have issues, as the
launch, climb, and recovery of the kite will likely be more than 9 minutes.
Reeling in 7000 feet of like takes a bit of time!

Steve

[Eric Greenwell[_4_]]

On 9/24/2012 6:25 AM, Steve Leonard wrote:
> On Monday, September 24, 2012 12:10:39 AM UTC-5, Eric Greenwell
> wrote:
>
> Here is a rocket logger: altitude, temperature - $80
> http://www.perfectflite.com/sl100.html
>
> May have to get one of those. But again rockets are not the way to
> go for recurring cost. As I recall from talking with one of our
> local rocket guys, they are $30 and up per shot. Don't mind a few
> more bucks to get started, but hate recurring costs.
>
> Thanks for the searching, Eric. If I get one, I will let you know
> how the kite flying and data collecting goes. That one might have
> issues, as the launch, climb, and recovery of the kite will likely be
> more than 9 minutes. Reeling in 7000 feet of like takes a bit of
> time!

Maybe use the old kite flyers trick of sending the instrument pack up
the string in a little pod with a sail, once the kite is at altitude.
Or, reverse it: have the pod slide down the string from the kite after
it's up, and have even quicker access to the data.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Tony[_5_]]

On Monday, September 24, 2012 11:48:37 AM UTC-5, Dan Marotta wrote:
> Steve, Would XCSkies work for your needs? I see, looking at the map for Hutchinson, that you should be getting lift up to 2,000' AGL right now! "Steve Leonard" > wrote in message ... On Monday, September 24, 2012 12:10:39 AM UTC-5, Eric Greenwell wrote: Here is a rocket logger: altitude, temperature - $80 http://www.perfectflite.com/sl100.html May have to get one of those. But again rockets are not the way to go for recurring cost. As I recall from talking with one of our local rocket guys, they are $30 and up per shot. Don't mind a few more bucks to get started, but hate recurring costs. Thanks for the searching, Eric. If I get one, I will let you know how the kite flying and data collecting goes. That one might have issues, as the launch, climb, and recovery of the kite will likely be more than 9 minutes. Reeling in 7000 feet of like takes a bit of time! Steve

xcskies is still a model based forecast. when the model is broken it doesn't matter if dr. jack or xcskies is interpreting the data it still will be wrong.

[Steve Leonard[_2_]]

On Monday, September 24, 2012 12:00:59 PM UTC-5, Eric Greenwell wrote:

Maybe use the old kite flyers trick of sending the instrument pack up the string in a little pod with a sail, once the kite is at altitude. Or, reverse it: have the pod slide down the string from the kite after it's up, and have even quicker access to the data.

-- Eric Greenwell

Well, the package would have to be on the second kite in my system. It seems that one kite on 1000 feet of string got to about 800 feet based on the altimeter watch that was used in initial testing. Adding another 1000 feet of string only got about 400 feet more altitude. Bigger kite needed. But, what to do with the smaller one, since the money was invested? Tie it to the main line on a 100 or so foot tether, and let it help in lifting the line. So, I won't have a 7000 foot long, clear shot up the line. I did learn some interesting dynamics of an intermediate, line lifting kite, though.

Interested in seeing the dynamic of a powered winch to reel the line in. Will have the effect of increased wind speed for the kites, so they should climb a little higher. First attempts were with people grabbing the line and walking it towards the reel (yes, the first 200 feet or so of the line was only 4-6 feet off the ground when we had, I believe, 3000 feet of line). I have seen what this line put on a Home Depot Extension cord reel does over time. I now have a big mess of kite string, as it contracted and split the ends off of the reel!

Steve

[Martin Gregorie[_5_]]

On Mon, 24 Sep 2012 10:53:55 -0700, Steve Leonard wrote:

> Interested in seeing the dynamic of a powered winch to reel the line in.
> Will have the effect of increased wind speed for the kites, so they
> should climb a little higher. First attempts were with people grabbing
> the line and walking it towards the reel (yes, the first 200 feet or so
> of the line was only 4-6 feet off the ground when we had, I believe,
> 3000 feet of line). I have seen what this line put on a Home Depot
> Extension cord reel does over time. I now have a big mess of kite
> string, as it contracted and split the ends off of the reel!
>
Talking to these guys may give some pointers to what can be done:
http://www.kiterecord.org/kiterecord/

They've had a single kite up to 10,466 ft, but it was a big one: 16 m^2

I also remember hearing that US meterologists got the top kite in a
string to 25,000 ft in the late 1930s, but can't find a reference to
quote.

I'd say that a rocket instrument package would be a good starting point
because its light: put it under a fairly large Rogallo-type kite and fly
it on light, low drag line (Spectra or Kevlar?) and you should get the
height you want. Light and low drag and large are all important since the
kit's lift must support the weight of the whole rig as well as offsetting
the drag of line and kite. Some sort of winch would be good too, even if
its only a geared (multiplier) sea-fishing reel.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Papa3[_2_]]

On Monday, September 24, 2012 1:02:02 PM UTC-4, Tony wrote:
> On Monday, September 24, 2012 11:48:37 AM UTC-5, Dan Marotta wrote:
>
>
> xcskies is still a model based forecast. when the model is broken it doesn't matter if dr. jack or xcskies is interpreting the data it still will be wrong.

Yeah, but...

It seems to me that the models are more often wrong about the parts of the forecast that wouldn't be "fixed" by a local sounding.

There are obviously times (e.g. exact timing of a frontal passage) which can make a difference between a soarable day at the local airport and playing golf, but in such cases a morning sounding wouldn't matter. Similarly, we can have a perfectly good boundary layer in place but a pesky short-wave aloft produces a alto-cu layer just where we didn't need it, killing our heating. Again, that one wouldn't be caught by the local sounding. Same for advection of some slightly drier air that takes our day for 3/8 Cu to blue.

I'd be curious if Dan Gudgel or Walt Rogers would weigh in on this one. Maybe I'll just ask :-)

P3

[Bart[_4_]]

I once toyed with an idea of putting a temp/rh/pressure logger on a RC
plane with an autopilot. It would climb on its own, gather data, come
back to the launch site and fly in circles until an operator turns on
a radio and guides it to a landing.

I decided against it because of legal issues. While I do not know all
the relevant laws, I am pretty sure that an amateur-built UAV flying
close to an airway (that's where my club is located) would be frowned
upon.

I am sure that unmanned balloons and rockets are subject to their own
regulations.

On the other hand, building a sensor package to be carried by an
ultralight or a kite would be relatively easy.

Bart


On Sep 14, 6:12*am, Anders Petersson > wrote:
> Hi
> I have developed a system "Windsond" to gather local wind data at different altitudes in an easy way. This is done by launching a 60 liter helium balloon with electronics that transmits back sensor data as it ascends. On the ground, a laptop receives the data and displays diagrams of wind speed, direction and temperature.
>
> The idea is not new, and weather balloons are indeed launched daily all over the world. The novel thing is the light weight and low cost, for a system adapted for altitudes up to 3000m. We use this for hot air balloons where we also recover the electronics again with a success rate around 80%.
> More information and pictures here:http://kiwiembedded.com/windsond/
>
> From discussing with a glider pilot, it seems this could be interesting for your sport as well. But you also want humidity readings, right? I'm interested in your comments and what potential you see. Looking forward to hear from you either here or on email .
>
> Thanks for your time,
> /Anders Petersson
> *Embedded systems designer

[Anders Petersson]

Hi again
I'm sorry I disappeared from the discussion. I thought I would get email notifications of new replies.

The technical solution has become more mature since September. It now supports humidity measurements. Radio range is much improved and testing will hopefully confirm support for altitudes of 7-9 km.
The weight is optimized to the point where 30 liters of helium should suffice. This makes a sounding very cheap as long as the electronics is recovered. We're looking into offering a variant for one-time use but haven't determined what pricing is possible yet.

As for alternatives, I don't see how a kite could measure winds and altitude is limited indeed. Results from a rocket would be inaccurate due to high vertical speed. In both cases, the payload can detach at peak altitude and take measurements while falling to the ground. That would mean the electronics still has to be retrieved some distance away.
A helium balloon is cheap but these other solutions would also work with Windsond. Approximate GPS coordinates of landing site together with loudspeaker, radio beacon and flashes of light makes it easy to recover.

We're now working to estimate the market to motivate production. In parallel, I'm doing development and testing. Your comments are valuable!

Regards
/Anders Petersson

[Steve Leonard[_2_]]

Good that you are making progress, Anders! Keep us posted!

Steve

[Todd]

Why not just put the instrument package into a radio control aircraft (aka: Drone) and fly it as high as you want and have it come back home with your $150 instrument package? Surely someone has come up with an R/C autopilot system by to to deal with the issues of visually flying an aircraft you cant see.

[Craig Funston[_2_]]

On Thursday, December 6, 2012 4:07:58 PM UTC-8, Todd wrote:
> Why not just put the instrument package into a radio control aircraft (aka: Drone) and fly it as high as you want and have it come back home with your $150 instrument package? Surely someone has come up with an R/C autopilot system by to to deal with the issues of visually flying an aircraft you cant see.

It's a pretty easy problem to solve except there are restrictions on altitude for unmanned aircraft. http://www.micropilot.com/

Craig

[Anders Petersson]

Yes a UAV (aka drone) would be convenient. It would need to be very reliable to offset the cost of losing the more valuable airframe. The cheapest Micropilot circuit I find is $1500; I'm sure there are cheaper ones but you still get a lot of helium balloons for the price.

Craig is right, max UAV altitude is normally 400 feet.

[Craig Funston[_2_]]

On Friday, December 7, 2012 6:52:28 AM UTC-8, Anders Petersson wrote:
> Yes a UAV (aka drone) would be convenient. It would need to be very reliable to offset the cost of losing the more valuable airframe. The cheapest Micropilot circuit I find is $1500; I'm sure there are cheaper ones but you still get a lot of helium balloons for the price.
>
>
>
> Craig is right, max UAV altitude is normally 400 feet.

There have been a number of amateur balloon lofted model glider flights with trackers in the glider. Does a balloon lofted glider with a return home autopilot & tracking beacon avoid the UAV restrictions?

Cheers,
Craig

[Anders Petersson]

I checked with the Swedish authorities and at least here, the rules are the same for unpowered flights. High altitude and without visual contact mean unsurmountable regulations.

/Anders

[Anders Petersson]

I'm looking into regulations for small weather balloons.
Does anyone know if I'm correct to interpret FAA FAR part 101 to mean that balloons with payloads lighter than 4 lb are exempt from NOTAM and other permits?

Here's the FAR part 101 I refer to: http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&rgn=div6&view=text&node=14:2.0.1.3.15.1&idno=14

Grateful for any help.. US regulations is far from my field.

[Anders Petersson]

I'm now looking for a few glider pilots to try the Windsond system. Some information is at http://kiwiembedded.com/windsond but the offer itself isn't public. Contact me at for pictures and other details.

Regards
/Anders

Den fredagen den 14:e december 2012 kl. 23:12:41 UTC+1 skrev Anders Petersson:
> I'm looking into regulations for small weather balloons.
>
> Does anyone know if I'm correct to interpret FAA FAR part 101 to mean that balloons with payloads lighter than 4 lb are exempt from NOTAM and other permits?
>
>
>
> Here's the FAR part 101 I refer to: http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&rgn=div6&view=text&node=14:2.0.1.3.15.1&idno=14
>
>
>
> Grateful for any help.. US regulations is far from my field.