lghtning21

I am working with a research group developing an electric multirotor craft with will be flying and hovering near power lines and the poles/towers; we will need to fly within a few inches of the lines (more details upon request). I have heard a lot of information about flying around or near power lines and have been getting mixed information about the effects the lines will have.

I am looking for input on the following items:

What frequency will yield the best performance?
Will there be any effect on real time video transmission?
What are the effects of corona, emf, etc on the craft?
Should there be any consideration of electrical shielding?
and any other information please.

I am looking for only expert responses please. If you can, please state your credentials.

Thank you

dirtybird

My Feedback: (5)

I have a BSEE from the University of Nebraska - 1954.
Unfortunately I don't have the foggiest notion of the answers to your questions.
I can tell you it would not be wise to hit one of those power lines.
The Boeing club had an excellent flying next to some power lines. One day a flier hit the lines causing a short. This started a chain reaction that ultimately resulted in power loss to Seatac Airport. Some of the computers controlling flights went down.
The power company told Boeing they did not want any model aircraft anywhere near their power lines.
The end result was the disbandment of the Boeing Hawks club.

Gizmo-RCU

My Feedback: (27)

DUMB!!!!!!
Is there not a better way to determine what you are looking for?
Does this really have a place in our hobby?
I could go on and on, but will spare you from what I am thinking.....[>:]

Gizmo-RCU

My Feedback: (27)

By the way I have a degree in COMMON SENSE!

lghtning21

This is for a Mechanical Engineering Senior Design project. We have the sponsorship of the power company and are working directly with one of their contractors. I am not sure if I can publish either of their names at this time, but I can say that we have the authority to proceed with the project.

rmh

Sounds like a ship of fools
do have any idea what the voltage can be on these lines and how far power can be from each attaching point on insulators?
We fly very tiny foamies within 50 ft of primary feed towers but I would not consider flying anything else nearer.

dirtybird

My Feedback: (5)

I have been thinking a bit about your problem.
Each one of those power lines has a large magnetic field around it generated by the current passing down the wire.
If your hovercraft has conductive blades they will generate electric current when they pass through the magnetic field. This is the same process used to generate electricity.
The question is what is going to happen to that generated electricity. It could blow out circuitry used to control the craft.
At any rate be sure to ground any one of the craft after a flight before you touch it. It might be highly charged.
Does your school have an EE dept? You might want to run this by them.

lghtning21

The lines will be anywhere from 13kV and 70kV though most of the lines we are concerned with will be on the lower end.

lghtning21

The blades will be non conductive.

The crafts we are currently looking at are from Mikrokopter
http://www.mikrokopter.us/shop/index...tegory&path=37


We do have an EE dept and will be checking with them to see their concerns.

Gizmo-RCU

My Feedback: (27)

Is there not a way to tether the craft to ensure no accidents? Remember Murphy's law.
If something goes wrong be sure to point out that you are not a RC'er....

lghtning21

We must have a 1000ft range so a tether would be impractical.

I have been working with RC vehicles for about a decade but never flight or near any utility structures.

MajorTomski

May I suggest you contact a manned helicopter based powerline inspection/repair company? they would have experiance in most of these fields.

skeeter_ca

Like these guys.

http://www.youtube.com/watch?v=kh8Zu...eature=related

Looks like fun.

skeeter

Hill202

My Feedback: (24)

There is no amount of money that would get me to do that.

MinnFlyer

My Feedback: (4)

Yes, this is done all the time with full-scale helicopters, I see no reason why it could not be at least attempted with RC

Let's face it, birds land on those wires all the time. You will have no problem of shorting out if you touch one. Now, if you touched two at the same time, or one wire plus the ground, THEN you would see some pretty sparks!

The biggest question would be: Would the EMF play havoc with the radio signal? Only one way to find out

Try a 2.4GHz radio with frequency hopping like the Futaba FASST system

sidgates

My Feedback: (2)

My formal education doesn't apply here so won't bother with that. I recently ran a ground range check on my Weatronic 12CH on 2.4GIG. I had line of site for 2700ft. and there was no loss of control. At about 1500ft. I went under a high voltage line. The Weatronic records the RF strength every 1 sec. in a log file. In reviewing the file I could easily see the loss of the RF power while I was near the Power Line. I don't remember the exact readings but I remember I was surprised how much effect the line had and surprised I didn't have any frame loss under the line.

Several years ago I flew at a field that had a power line on the west side about 1200ft away. At that time most models were on 27MHZ and if we got within 20-30ft. of the line the model would lock up and spin in. These were very broad band receivers.

Rodney

Dirtybird and Minniflyer both gave what I consider good advice. As an EE myself, I think your project is a very interesting one and well worth pursuing as long as you take reasonable precautions. Strong flux fields that exists around current carrying conductors do present some interesting problems and your pursuit of answers can be both a challenging and rewarding situation. Good luck and let us know how things turn out.

HoundDog

My Feedback: (49)

[quote]ORIGINAL: lghtning21

This is for a Mechanical Engineering Senior Design project. We have the sponsorship of the power company and are working directly with one of their contractors. I am not sure if I can publish either of their names at this time, but I can say that we have the authority to proceed with the project.
[/quote
Just because some one works for the power company doesn't make them "Real Smart" in fact maybe they should resign before they hurt someone. Our hobby doesn't need any (more) bad publicity. If u need to inspect some thing high up get a camera on a stick and make sure U ain't grounded.

MinnFlyer

My Feedback: (4)

Speaking of "Real Smart"

I'd venture to say that using an RC helicopter is a tad bit safer than a "camera on a stick"

Sport_Pilot

I suspect that if the craft was made of nonconductive plastics, foam, fiberglass, etc. Then covered with foil, then another coating of rubber or fiberglass. And the only thing sticking out would be the antenna, and a surge protector between the antennal and reciever,
then it would be protected from the field.

The surge protector would be similar to the lightning arrestorsused to protect radios from lightning, butsmaller. It would also have to have a lot of air teminials to discharge the lightning strike instead of a ground.

http://www.durhamradio.com/lightning...io-canada.html

http://www.ehow.com/info_7771875_lig...-arrestor.html

dirtybird

My Feedback: (5)

You are confusing an electrostatic charge with an electromagnetic field. The fields surrounding those wires is electromagnetic - similar to the field surrounding a magnet. Aluminum foil is not a good shield for magnetic fields. You need a Ferris material.
Lightning arrestors require a ground to discharge their charge to. A ground is the last thing you want in this situation.
Any helicopter with its whirling blades will pick up a static charge but you need to discharge that when you return to base before you land.

lghtning21

Part of what we are doing is eliminating the stick as some targeted locations will not allow for a long stick or boom truck. Also, if we were just concerned with inspecting the poles and lines there wouldn't be much a problem if our camera had decent zoom capabilities. Visual inspection of power lines with a multirotor craft has already been accomplished:

http://rc-quadcopter.blogspot.com/20...nspection.html

We just need to get closer. I cannot say more do to our sponsors request.


The system in development is meant to improve safety for the linesmen. The dimensions of the crafts in question should not span the distance between phases


How can the Futaba FASST system help counter the effects of the powerlines?

Sport_Pilot

Not confusing anything, this is to protect it from flash over when flying too close to the power line. Not sure if the field will affect the radio or not. Lighning arrestors are used on aircraft with air teminals instead of a ground. The electricity passes though the arrestor to the skin of the aircraft and out the air terminals.

MinnFlyer

My Feedback: (4)

The FASST system looks throught the entire frequency range to find a clear channel. Once found, it switchs to that channel as it looks for the next clear channel. It "hops" to a new, clear channel every 400milliseconds.

Now of course, if the EMF is completely swamping the entire radio spectrum, you won't have much luck, but that's they system I would (and do) use.

http://www.futaba-rc.com/index.html

rgburrill

BSEE - 1969 - University of Washington
At that time BSEE meant electrical engineering and we spent more time on electric and magnetic fields than electronics. But since then I have stayed mostly in electronics - the main thing I remember about electrical engineering is the power lines kill.
That said, I would get your EE department heavily involved. I would also get your Physics department involved. Flying inches away from a 17KV line could have more of a magnetic problem on you helicopter than electric fields. Remember, not too many birds are full of metallic objects unless they are close to dying of mercury poisoning. And those great big helicopters are not going to be affected like your tiny ones. You will also have gyros that could be affected. And like it or not that rotor swirling inches away from that power line through the EMF fieldscould cause RF interference.
Remember, these are just my concerns. I do not have either the time, nor the inclination, to validate any of them. Personally I think you are asking for trouble but that is what college projects are all about

Thanks,
Bob

ps: Like one person suggested, if this works then please ground that aircrafft well before you touch it.