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Photoflying under bridges

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Hi guess someone here has experience of flying under bridges. In a week or so I know I will be asked to perform a surveillance flight under a bridge and as close to the underside as possible. My concern is how "riscy" it is to lose GPS sats (and crash) when under the bridge that is a 6-lane wide mixed steel/concret construction.
Shall I use the DBS/Itelite or std H antenna? Thanx in advance for your respons
 
yikes, you could fly it in non GPS mode, it should still hold altitude but will drift so a steady hand might be required. Make sure your RTH is not set too high, imagine watching it lift up up up into the underside of the bridge!

Anyway, good luck!
 
nicholas hickman said:
yikes, you could fly it in non GPS mode, it should still hold altitude but will drift so a steady hand might be required. Make sure your RTH is not set too high, imagine watching it lift up up up into the underside of the bridge!
Thanx Nicholas, I will hopefully be able to fly about one meter underneath the bridge...and using RTH is out of Q. Will I lose the GPS connections when under the bridge?

Anyway, good luck!
Click to expand...
 
nicholas hickman said:
yikes, you could fly it in non GPS mode, it should still hold altitude but will drift so a steady hand might be required. Make sure your RTH is not set too high, imagine watching it lift up up up into the underside of the bridge!

Anyway, good luck!
Click to expand...

Thanx Nicholas, I will hopefully be able to fly about one meter underneath the bridge...and using RTH is out of Q. Will I lose the GPS connections when under the bridge?
 
Photo said:
Hi guess someone here has experience of flying under bridges. In a week or so I know I will be asked to perform a surveillance flight under a bridge and as close to the underside as possible. My concern is how "riscy" it is to lose GPS sats (and crash) when under the bridge that is a 6-lane wide mixed steel/concret construction.
Shall I use the DBS/Itelite or std H antenna? Thanx in advance for your respons
Click to expand...
I am assuming you will have Los the whole time. So as far as antenna choice either will be fine but it doesn't hurt to have the extra dbi from the directional antennas. As far as gps goes you shouldn't have a issue. I say shouldn't. So freshen up on your unaided flight. Also one thing I would recommend is getting a different lens with more of a zoom like the peau 8.25mm lens. This will allow you to fly further away from the object with the same level of detail.
 
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Not really. But it all depends what you take as serious modding. Peau has a install service and I think carolina dronz does to.
The hardest part is the removal of the glue that holds the lens mount to the board. And a hobby knife ran ove it a few times does the trick.
 
Shadowolf said:
Not really. But it all depends what you take as serious modding. Peau has a install service and I think carolina dronz does to.
The hardest part is the removal of the glue that holds the lens mount to the board. And a hobby knife ran ove it a few times does the trick.
Click to expand...

Yes sorry, I was thinking as a UK user, D'oh. I don't know of anyone that offers the service here. I watched someone fit one on YouTube.
 
Shadowolf said:
I am assuming you will have Los the whole time. So as far as antenna choice either will be fine but it doesn't hurt to have the extra dbi from the directional antennas. As far as gps goes you shouldn't have a issue. I say shouldn't. So freshen up on your unaided flight. Also one thing I would recommend is getting a different lens with more of a zoom like the peau 8.25mm lens. This will allow you to fly further away from the object with the same level of detail.
Click to expand...
Thanx Shadowolf! Great response! Yes I will for sure fly LOS, as always! :)
 
It is highly probable you will lose GPS signal while under the bridge. Do not fly in Smart mode.
 
I think many pilots believe without GPS they are at risk of a crash. I see that here as a query often. I've flown very close to trains, bridges, metal towers, but not antennae arrays of any kind. I think you'll be fine with no GPS and using your skills and I assume you'll have a spotter? What happens to your light under that bridge? Will you be able to get enough exposure?
 
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Photo said:
as close to the underside as possible.
Click to expand...

While the cam can examine vertical structure obviously it can not point up at the underside of the bridge.

If it were a short run, GPS might not be a problem...It sounds like a longer run, so my suggestion is to pick a time with as little wind as possible, turn the GPS off, keep the drone in your sight, fly it manually in Angle mode. You need to have a dual setup so that someone else can operate the camera.

Good luck...
 
Photo said:
Hi guess someone here has experience of flying under bridges. In a week or so I know I will be asked to perform a surveillance flight under a bridge and as close to the underside as possible. My concern is how "riscy" it is to lose GPS sats (and crash) when under the bridge that is a 6-lane wide mixed steel/concret construction.
Shall I use the DBS/Itelite or std H antenna? Thanx in advance for your respons
Click to expand...
Rather you than me, Photo. If it were me I don't think I'd have accepted a job like that.

All I can say is that you get a bit of practice in with flying without GPS ('Cos you are likely to loose it under the bridge) and make sure your insurance is adequate. Also, a flight like that should attract a higher rate of payment from what you'd normally charge to reflect the risk.

Go to the site before day of the flight to do a site and risk assessment and decide whether it is reasonably doable. On the day it's GPS off, set RTH less than the height of the underside of the bridge if you can, and maintain very good LOS.

Good luck.
 
Like vision said. I would also add while there power up the H and get gps lock then walk under bridge if you can and see how the gps holds or not.
 
Photo said:
Thanx all of you for your tips and respons. Right now I will not accept this assignment.
Click to expand...
It is a high risk flight for sure. Obviously you have to fly with GPS off. Most bridges contain a lot of steel and that could affect the compass. Even a slight breeze will make it difficult to control around a bridge structure. If the agency agrees in writing to pay for a replacement bird then I might consider it as long as the risks are spelled out and they understand the potential for loss of the aircraft.
 
Flush,

The H doesn't really care about a GPS signal when flown in Angle mode. It's more reliant on the compass and baro altimeter for general stability. Position hold in hover improves when GPS is good, of course. You only really need GPS for RTH and Smart mode. The closer the H is to the bottom of the bridge the greater the probability GPS signal will be blocked by the bridge. GPS does not penetrate steel and concrete worth a ****, and the bridge will have a lot of both. Simply "shadowing" the H from GPS signals by flying low between a bunch of tall buildings can occlude a GPS lock. Being 6 lanes wide the over head satellite view will be severely occluded, with only the satellites on the far horizons being able to providing any signal from the sides of the bridge. Just remember you'll be hand flying the bird in what will essentially be a "stability" mode, and slow the speed slider some to make control more manageable.
 
PatR said:
Flush,

The H doesn't really care about a GPS signal when flown in Angle mode. It's more reliant on the compass and baro altimeter for general stability. Position hold in hover improves when GPS is good, of course. You only really need GPS for RTH and Smart mode. The closer the H is to the bottom of the bridge the greater the probability GPS signal will be blocked by the bridge. GPS does not penetrate steel and concrete worth a ****, and the bridge will have a lot of both. Simply "shadowing" the H from GPS signals by flying low between a bunch of tall buildings can occlude a GPS lock. Being 6 lanes wide the over head satellite view will be severely occluded, with only the satellites on the far horizons being able to providing any signal from the sides of the bridge. Just remember you'll be hand flying the bird in what will essentially be a "stability" mode, and slow the speed slider some to make control more manageable.
Click to expand...
I have made my decision - don't fly under the bridge! :eek:
 
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