Temp inversion measurements

[VK2KRR]

Just a crazy idea I have, not sure if anyone will be able to answer.

Im just wondering, if I could attach something to measure the vertical changes in temp & humidity underneath a radio controlled helicopter and send it up above into the air here, would the disturbance of air below the helicopter change the measured results of temp/humidity? or in the bigger scheme of things would any changes be minor if any?

I guess the blades would draw air from above and push it below, perhaps if the measurement device was dangled on a string a number of meters lower it may help ?

[VK3DXE]

How about a tethered balloon Leigh?

[VK5ZD]

Take it up with the helicopter then release it to fall on a parachute.
Take the measurements on the way down.

Iain

[VK2GOM]

I would use a small quadcopter rather than a heli. They only use small propellers rather than large blades, and are more stable, and easier to fly. Flying model heli's is akin to balancing a broomstick handle on each palm... with your arms crossed

Having said that, I don't think there will be that much air-mixing going on that would affect readings.

73 - Rob VK2GOM / GW0MOH

[VK3ALB]

What are you planning Leigh?

I know you already have a number of temp sensors at various heights on your tower which seems to be a very practical solution. If you wanted to take more measurements over a given height above ground it might be easier to put a remote temp sensor on a pulley up the side of your tower. I think it would be much easier to calibrate the sensor height on a pulley system than it would on a helicopter.

[VK2KRR]

Lou, Im not planning anything, I was just thinking about how I could get readings above the existing temp probes I already have at 6 ft and 50 ft on the sth tower.

Rob, interesting idea, that could be a goer, just need to find a suitable measuring device.

Iain, that could work but knowing my luck the parachute would get tangled on an antenna on the way down, or the power lines.

Alan, helium balloons cant carry much weight, unless there is a lot of them. I found that out with the 160m -- 1/4 wave balloon supported antenna I experimented with. Not really practicle and the helium gas is quite expensive if u wanted to do it every night.

Rob's quadcopter Idea is good. But what I need to know now is, is there any small device that could measure and log humidity and temperature?

[VK3AIF]

Hi Lee, have a look at the Vaisala web site, if you do no good there get back to me and I'll see what I can find.

You could always go stick a reflector up on top of the big stone just over the fence and hit it with a laser from your place and measure the refraction on the path because as you most probably already know, the refractive index of air changes with temperature and humidity, actually its density which is a product of temp, R.H. and barometric pressure but isn't that really what you are after, the refractive index?

Another maybe is get a hold of a radiosonde from a crashed weather balloon (maybe have a look around Roswell), or the met bureau and try lifting that with a remote control helicopter or one of its iterations but I wish you luck with that one as them anti-gravity gizmos don't have a lot of lift to spare. Maybe you could launch a radiosonde with a giant orange gun, a sounding rocket or here's the project, a rail gun? I see you have the makings of a new launcher under construction right now.

[VK2FAK]

Hi all...

I won't continue to check this thread for possible updates.....I will just watch the Ch-9 News for UFO reports in the south of the State....that will be the indicator to return to this thread to see what leigh came up with.....

John

[VK2XSO]

You can of course just get the data of the BOM or one of the various hang gliding websites.

But lets just say you want to do it yourself. The air you're measuring is not going to be effected by the helicopter's wash.
The humidity and temperature doesn't change just because you're fanning it

The biggest problem with a helicopter is power. They're not the most efficient flying machines so it depends on how high you intend to fly.
You're chopper may run out of fuel or battery power before it gets to an altitude you want. How high are you planning on flying it ?
The next is the range of the remote control, though I don't think you'll have much problem overcoming that.

I'm thinking you might be interested in just low level inversions. The kind that trap smoke in a valley. I saw a nice inversion that was about 400ft above ground level, so I'm guessing this is what you'll be looking for. It's not like you'll be flying to 10,000ft looking for the big inversions.

So assuming your sensors are somewhere where an engine can't warm them up, then flying a chopper up to 1000ft recording data as it goes the rotor wash will not effect the readings. The inversions are not like a thermopause in water where the layer forms a very thin boundary.

I fly my hang glider and paraglider through inversions all the time. The inversion is still a gradient, though much steeper. I don't really get the chance to fly through the early morning inversions but if I compare what I can see with trapped smoke I would think the inversion is probably only about 10 metres thick.
I might just have to go out and fly through one to find out the hard way.

The most obvious inversion layer I fly through is the one where cumulus clouds form. It's about 300ft thick.

[VK2KRR]

The issue with the BoM radiosonde balloons is that they move to quickly through the lower levels and dont provide many data samples between ground and say 1000m.

I already have a temp probe at 50ft so if I could get up to 200 ft even, I would be happy. Though if it was easy to take it up further I probably would also.

[VK2GOM]

Leigh - I have found your solution: The Arducopter. Basically a quadcopter controlled by a fairly clever Arduino based core that includes various levelling and inertial sensors including GPS so it will follow a preset flight plan of points (lat/long) and altitude, so you could program it to go up to x hundred feet over the course of y seconds through the included software interface, set it going on its task, then have it come back to where it started and land itself. No human intervention required.

Ready to fly, they run to about $700 US which is actually very cheap for an autonomous robotic programmable drone. Google will find it easily.

They have good lifting capability, and will easily carry a GoPro camera in its housing, so will manage a USB stick based temperature logger with no problems at all. In fact, why not add a humidity sensor too?!

I think the comment about lack of lifting ability might have been judged from Chinese toy helicopters that are sold almost everywhere these days. My big electric model heli will easily lift 1.5kg, no problems at all. Of course the flight envelope changes somewhat but it's still flyable, with the motor pulling about 75A from a 22.2V LiPo battery.

73 - Rob VK2GOM / GW0MOH

[VK3HZ]

Interesting idea to use a multicopter: http://code.google.com/p/arducopter/wiki/ArduCopter

The Arducopter board (known as the Ardupilot Mega 2 (APM2)) already has onboard data logging. It certainly logs position and altitude (barometric pressure) and I think there's also temperature. Wouldn't take much to add humidity. With the addition of a telemetry link (915 MHz), the data can be sent to the ground station laptop where it is also logged and can be displayed in realtime.

Other applications could include inspection of antennas. A GoPro will make an HD recording, but also give a live video output that can be sent to the ground via an AV Sender for realtime viewing.

Limitations are that legally you can only fly to 400 ft and must remain within visual range.

Another limitation may be flight time. With a 11.1V 5AH LiPo battery, I get about 12 mins from a quadcopter (with camera). I guess that would be enough to do a slowish ascent, then return to landing before running out of joules. It doesn't glide very well (like a rock)

Regards,
Dave.

[VK2GOM]

...Limitations are that legally you can only fly to 400 ft and must remain within visual range.

Very true Dave.

...and unfortunately require at least a 'Bronze Wings' from the MAAA to fly without supervision, and fly only from an 'approved model flying site' as recognised by the CASA.

...which effectively makes all the cheap Chinese market flying toys flown in public parks by the young and not so young all illegal

But again, it's one of those over-regulated and unenforceable scenarios.

Let me know when you get the quadcopter, Leigh! I might even be interested in flying something with 4 main 'blades' rather than two!

73 - Rob VK2GOM / GW0MOH

[VK3HZ]

...and unfortunately require at least a 'Bronze Wings' from the MAAA to fly without supervision, and fly only from an 'approved model flying site' as recognised by the CASA.

Getting rather OT but ... the MAAA might want you to believe that, and enforce it for club flying for you to be covered by their insurance, but it's not law and not a requirement for flights elsewhere.

The 400', Visual (and not within 3NM of an Aerodrome) requirements are laws: http://www.maaa.asn.au/maaa/pdf/notices ... 0small.pdf

Mind you, flying a multicopter, helicopter or R/C aircraft of any kind is not a trivial task. Like most skills, it takes quite a bit of practice. Despite the impressions given, the Arducopter will not fly autonomously straight out of the box. It requires setting up and tuning which requires manual flying.

Regards,
Dave.

[VK5PJ]

Leigh,
powered lift devices aside for the moment, the balloon suggestion deserves investigation, you can either choose to fly it on a tether like fishing line for instance or do a fly and loose style mission (like the met people do).

You could also talk with the project Horus team about their balloon tear down scheme, so you can retrieve the package, the tear down is a piece of nichrome wire around the kneck of the balloon that when attached to the battery cuts the kneck of the balloon off, than have a parachute for the decent. but hey thats quite complicated. The down side with the balloon is having the gas to inflate it on hand for the odd times you want to make a measurement.

No matter what you go with, you will need telemetry to send the data down, once again talk to the Project Horus baloon team about their low power data TX made from the 434MHz buz bomb transmitters.

hmmm 200' up, okay any high hills you can stick a sensor package on, maybe that one to your east?

Peter, 5PJ

[VK2XSO]

Actually, that makes me laugh because the first balloon we launched was a party balloon.
I built a simple temperature transmitter using an old LIPD. All the parts came from wyong field day.
The LIPD was from a box of weather sensors which also had a thermistor and humidity sensors. The battery I used the small lithium cells stripped from the cheap micro helicopters. They were wired together with a simple 555 timer used as a modulator and I calibrated the tone with some freeze spray on the bench.

That was the last I saw of the transmitter before it was taken away to fly on a party balloon.
The local scouts launched it an hour later and I listened to it's flight. I had no tracking on it, all I could hear was the tone from the modulator.
From the altitude charts on the day and the time it took to fall (about 90 seconds) it went up to almost 20,000ft before it burst.

What jogged my memory was the sound it made as it fell. I could hear it fall through three inversions. So while this method doesn't exactly give you altitude it does give an example of something cheap.

Now I suspect you have a piece of dirt somewhere close which is about 1200ft high. A couple of lipd's with small rechargable lithium batteries and a tiny solar cell. A PIC chip to have them transmit about once every couple of minutes to save power. I would think the 1200ft is enough to get you above a local morning inversion.