Urban Flying tips

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Just wondered if anyone with some urban flying experience would care to share some tips on how to best fly in a concrete jungle such as this one in downtown LA: http://vimeo.com/101231747

I've done most of my flying with a P2 FPV rig in rural settings and am just putting my new P3P through some careful tests/initial flights. I plan on getting far more experience with the P3P before attempting any urban flying, but I'm wondering how other brave souls have handled issues unique to the urban landscape. For example, the linked video at 1:24 sec with medium-tall bldgs all about, concrete as far as the eye can see. Where do you take of and land (hand catch?) from this kind of setting? With no grass areas available do you typically take off and land from ground-level concrete areas after using some type of magnetic sniffer app to look for an area safe enough to do so? (so that any hidden metal won't cause compass errors that would effect flight) I presume that a good calibration from a flat grassy field should be left alone and not attempted anywhere near concrete, but looking for any advice here. Also wondering if you can safely launch down between valleys of buildings presuming a certain threshold of satellites and LOS, or if trying to gain some elevation on top of structures is a valid strategy. And are you guys typically using standard P-GPS mode for your urban flights or going right into A-Atti, or F-course lock for certain environments/effects?

Thanks in advance for any advice.
 

Meta4

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do you typically take off and land from ground-level concrete areas after using some type of magnetic sniffer app to look for an area safe enough to do so? (so that any hidden metal won't cause compass errors that would effect flight) I presume that a good calibration from a flat grassy field should be left alone and not attempted anywhere near concrete, but looking for any advice here.
You are right - don't mess with a good compass calibration to replace it with a potential problem caused by calibrating in the presence of large steel structures like the reinforcing in a lot of concrete.
Look for asphalt or grass for a launch point.
Also wondering if you can safely launch down between valleys of buildings presuming a certain threshold of satellites and LOS, or if trying to gain some elevation on top of structures is a valid strategy. And are you guys typically using standard P-GPS mode for your urban flights or going right into A-Atti, or F-course lock for certain environments/effects?
If enough of the sky is blocked, GPS cover could be a problem.
Now that the IOS app (and soon the Android version) supports resetting home point, It is possible to launch in GPS or atti and go up above the trees, buildings or other obstacles, reset a home point up there right above the window you want to come back to for landing and higher than the surrounding obstacles so RTH would be safe. If GPS is touchy in the launch area you'd have to be prepared to guide her down in atti.
But be aware of the potential issues losing connection if you don't have a clear line of sight from your spot down below.
 
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But be aware of the potential issues losing connection if you don't have a clear line of sight from your spot down below.
Last week I did quite a few beach flights where I lost GPS due to terrain. But it wasn't a particularly big drama as the wind was consistent (onshore), I still had line of sight on the unit, and I could revert to FPV for localiser cues to bring it home in ATTI mode, having spent a lot of time practicing in ATTI due to a naff GPS reciever that i've since upgraded :)

Urban environments are a totally different ballgame. Even a light breeze can cause havoc when it hits a large structure and causes eddy currents around it. You could easily find yourself in a situation where GPS is lost due to an obstruction, leaving you at the mercy of the winds, with no spacial awareness because you can't see where you are, especially if FPS goes down too.

Things could get very sticky very quickly.

Edit: here's a video of me losing GPS (drift to the left at 0:10). Solution = corrective yaw and bring it back ASAP!

 
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You may want to first check the legal status of RC flight in LA. Many cities have laws against such a thing.
 
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Make sure you don't let a large building pass between you and the P3. That will almost certainly kill your connection to the FPV and maybe controller. Lightbridge is very sensitive to obstacles. You might also want to make sure your RTH attitude is set higher than the tallest building in your area in case you DO lose a connection and it tries to go through a building (Spoiler: the building will win). Just make sure that's not over 400' of course, LA has pretty busy air space.
 
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Absolutely critical to check the height you have set for RTH. If you lose signal behind a building, you sure don't want it trying to go through the building to get back home, because if you haven't set a high enough RTH height, it will do just that.
 
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Yep, setting the RTH height based on my location is something I make a priority of, although I notice on the P3, even though I have imperial units checked, it still gives the RTH height in meters. BTW, I'm not in the LA area at the moment, I just linked to that video because it illustrated the take off/land questions I had very well. The dangers of taking off from rebar with metal in it is illustrated well in the 3rd video on the 3rd page of this thread: http://www.phantompilots.com/threads/the-compass-misunderstood-or-easy-scapegoat.39304/

I personally think the importance of this issue (metal causing variance between the IMU and the compass) when taking off or flying in any type of urban area is something that should be given far more attention. After spending a few hours searching posts in this forum, I've found a few snippets of information here and there, mostly from Ian Wood, a moderator of this forum (and creator of that LA video I linked). He mentions in a couple of posts that his biggest issues with urban flying were getting CLS and satellites and "finding a safe place to take off from," and further mentions using an app that gives raw compass data, presumably to determine the safest locations on concrete to take off from with the least magnetic disturbance. Along these lines, I'm wondering if anyone has determined any rough guidelines of micro tesla interference in the field that they try to stay at or below?
 
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I gave only flown near the city as with only one battery it is useless for me to travel far. I live on a hillside beside a large city and fly off the roof. I have only flown about 1/2 mile away but it is over many many buildings- some small some tall. I set my rth for about 250 ft. Once and a while I will lose signal with the controller but by moving the P3 around a bit it comes back with in seconds. I only once lost the signal completely with it filming some fireworks it went it to rth and returned right back to me- did not get signal back till it landed- was very stressful but went right back up to finish and had no problems
 
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You are right - don't mess with a good compass calibration to replace it with a potential problem caused by calibrating in the presence of large steel structures like the reinforcing in a lot of concrete.
Look for asphalt or grass for a launch point.

If enough of the sky is blocked, GPS cover could be a problem.
Now that the IOS app (and soon the Android version) supports resetting home point, It is possible to launch in GPS or atti and go up above the trees, buildings or other obstacles, reset a home point up there right above the window you want to come back to for landing and higher than the surrounding obstacles so RTH would be safe. If GPS is touchy in the launch area you'd have to be prepared to guide her down in atti.
But be aware of the potential issues losing connection if you don't have a clear line of sight from your spot down below.
Thanks Meta4, good points, all. I would likely not push the issue of lilne of sight and satellites by making very careful and relatively short flights with the awareness that I might have to fly in atti at any time. I'm using android at the moment so I'm looking forward to that next update.
 
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Last week I did quite a few beach flights where I lost GPS due to terrain. But it wasn't a particularly big drama as the wind was consistent (onshore), I still had line of sight on the unit, and I could revert to FPV for localiser cues to bring it home in ATTI mode, having spent a lot of time practicing in ATTI due to a naff GPS reciever that i've since upgraded :)

Urban environments are a totally different ballgame. Even a light breeze can cause havoc when it hits a large structure and causes eddy currents around it. You could easily find yourself in a situation where GPS is lost due to an obstruction, leaving you at the mercy of the winds, with no spacial awareness because you can't see where you are, especially if FPS goes down too.

Things could get very sticky very quickly.

Edit: here's a video of me losing GPS (drift to the left at 0:10). Solution = corrective yaw and bring it back ASAP!

Thanks for your comments, cjmwales. Eddy currents and higher winds aloft is something that I need to plan on happening for sure. I will likely pick almost dead calm days if at all possible, but the winds aloft will be higher and much more of an issue If I have to go into atti. My flights will be short and remain in full sight, so losing FPV is a little less of an isuue, but I certainly don't want to experience that! I'm curious what was causing your GPS loss in your beach setting. How many satellites were you getting typically?
 
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What is the max range threshold you guys use to decide whether or not to recalibrate the compass. I'm going to be bringing the Phantom into work, about 20 miles or so from my last launch. Don't like messing up a good calibration.
 
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Thanks for your comments, cjmwales. Eddy currents and higher winds aloft is something that I need to plan on happening for sure. I will likely pick almost dead calm days if at all possible, but the winds aloft will be higher and much more of an issue If I have to go into atti. My flights will be short and remain in full sight, so losing FPV is a little less of an isuue, but I certainly don't want to experience that! I'm curious what was causing your GPS loss in your beach setting. How many satellites were you getting typically?
I took off with 8. There was intermittent cloud that may have contributed, or perhaps multiple satellites were only slightly above the horizon to the north & moving out into the bay compromised the line of sight (in the case of the video).

In the other beach scenario it was definitely me flying the phantom too close to a cliff. The winds were very strong but consistent, and as soon as it went into ATTI I reverted straight to the FPV to help me judge the corrective movements.

Video of that below. I think my face says it all at the end of the clip!

 

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What is the max range threshold you guys use to decide whether or not to recalibrate the compass. I'm going to be bringing the Phantom into work, about 20 miles or so from my last launch. Don't like messing up a good calibration.
20 miles is nothing ... I'm happy anywhere within 100 miles and depending on where you are and the direction you travel it could be safe over even larger distances.
Have a look at these maps to see how the earth's magnetic field varies.



 
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Great map. And the link is very informative as well.
 
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I took off with 8. There was intermittent cloud that may have contributed, or perhaps multiple satellites were only slightly above the horizon to the north & moving out into the bay compromised the line of sight (in the case of the video).

In the other beach scenario it was definitely me flying the phantom too close to a cliff. The winds were very strong but consistent, and as soon as it went into ATTI I reverted straight to the FPV to help me judge the corrective movements.

Video of that below. I think my face says it all at the end of the clip!

Well, you got it back, but when you think about what these things can do and how far they could fly, I think that look is warranted. lol. Man, that is some serious beach there - just HUUUGE! I can see why you are trying to capture it on film, very inspiring and beautiful. Love the significant other and the dog waiting patiently in the background. Bet she can cook too. Lucky man.
 
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Well, you got it back, but when you think about what these things can do and how far they could fly, I think that look is warranted. lol. Man, that is some serious beach there - just HUUUGE! I can see why you are trying to capture it on film, very inspiring and beautiful. Love the significant other and the dog waiting patiently in the background. Bet she can cook too. Lucky man.
Actually I do all the cooking! I did bore her to death during the holiday with constantly stopping to prep and launch - but she came round to the idea when we watched the footage back on the TV. It captures holiday memories from a completely new and mind-widening perspective.

That beach is called Porthtowan, and it's on the north Cornish coast. It's pretty small compared to this one - Godrevy / Gwithian:

And Hayle / St Ives Bay:
This clip is particularly interesting for the colours of the river that runs into the atlantic. You don't get to see those green shades from ground level. This was another flight where I was losing GPS - I relied on FPV to get the Phantom back via what I call the 'spotting' technique - pick something obvious to fly from that's big enough to show up on the FPV view, in the case of that flight there was a pretty big beach flag I could rotate to aim for to bring it home. Flying VFR!

We are truly blessed with some incredible scenery on this island.
 
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