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John Hamilton
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I have a project that is located at 3500+ m elevation. I am trying to find out which drones can fly that high, but the discussions have all been about "you can't fly higher than 400 feet". Of course, I would still keep the drone relatively close to the surface, but how well can they fly at that altitude? The small planes I fly have a lot of trouble climbing above 3500 m, especially on a hot day (high density altitude). 

So I am not talking about flying high above the ground, just flying normal altitude above the ground at a location that has a very high ground elevation. 

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GigHarborSurveyor
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It's called density altitude. You can probably find some charts that you can use for this. You have to input the temperature and humidity. When I flew helicopters this was a standard pre-flight item to make sure you had the power you need when flying at altitude, and in particular hovering. Higher and warmer means much less dense air and less volume for the blades to work with to create lift. 

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paden cash
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Posted by: @gigharborsurveyor

It's called density altitude. You can probably find some charts that you can use for this. You have to input the temperature and humidity. When I flew helicopters this was a standard pre-flight item to make sure you had the power you need when flying at altitude, and in particular hovering. Higher and warmer means much less dense air and less volume for the blades to work with to create lift. 

When I was a kid we lived in a Buena Vista, CO at about 8500' to 9000' msl.  Just south of town there was a small dirt strip and a wind sock.  We use to ride our bikes down there on hot summer afternoons and watch the planes try to take off before they got to the aspen trees at the end of the RW.  This was in the early '60s and few SEL planes had 150 t0 200 hp.   Pack a Cessna 170 full of vacationing travellers, luggage and full tanks combined with the (at that time) hardly 2000' RW and somebody was either going to mow the aspens or drop the plane into sheep pasture.  I saw a couple of pilots try to abort their take-offs and wind up with their gear torn off in the ditch at the end of the RW.

I don't remember anybody ever getting hurt, except for their pride or their pocket book.  But every year by Labor Day there was always 2 or 3 ailing hulks that had been dragged back up to the runway for a road trip to the nearest A&P facility. 

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GigHarborSurveyor
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For any particular drone, look up the Max Service Ceiling. For the Mavic, I think it it 5000m, so probably similar for other, though some have high altitude props available.

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gschrock
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There are high altitude props for DJI Inspire 2's that they claim can go up to 5000m. For s stunt someone did a video of an eBee near the top of the Matterhorn.

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chris mills
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John,

Depending upon exactly what the job is, one of the QuestUAV fixed wing aircraft may be what you need. We use a standard Q200, but they do high altitude versions of both that and the Datahawk which have flown at similar altitudes to your requirement. They will customise to suit needs (we are currently assisting them on a project integrating a multispectral camera with PPK for use over shallow water). The aircraft comes in a modular form for easy transport, so it is straightforward to use either standard or high altitude wings (but not one of each!!)

Contact is Stuart King :  [email protected]

The advantage of a fixed wing, especially at altitude, is that you need considerably less power out of the battery so flight times are much longer - typically we can push 50 minutes at sea level with our standard one. They have sold several to Kazakstan area - heights around 7000ft.  I think those were standard models.

As regards flying height, if the accuracies you want will permit then applying for a height exemption is worthwhile. I was very surprised at how much quicker the area was covered on the multispectral trials when it was flown at 800 ft. AGL, still with good resolution. The Q200 comes with a 24mp Sony as standard.

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GigHarborSurveyor
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@chris-mills

I'd like to hear about what you are doing wrt the shallow water multispectral. I have been researching methods of near shore algae and submerged plat growth inventory to try and put a solution together. 

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chris mills
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@gigharborsurveyor

I can't make much comment - Quest are supplying data and a fixed wing UAV to the military - nothing sinister as far as I know, but just part of looking at shallow water/beaches. We've been providing ground control, checks and doing data processing.

We've done a little work of our own, a couple of years ago, just using normal photography to see what sort of information we could glean on shallow water. prompted by the need to get ground surface data in shallow flooded areas in quarries where wading in would be unsafe. results were published in Geomatics World  see link below for our results

https://www.geomatics-world.co.uk/magazine/september-october-2017

I understand that Quest hope to make the multispectral set-up generally available. It uses a PPK card from Septentrio. If you express an interest I'm sure they could consider flying some suitable water nearby, or there might be some existing imagery available. You realise that the quality from a multispectral sensor is of much lower resolution than a normal camera. I've just looked at one of the recent orthophotos, showing the inter-tidal zone, and I find it hard to tell between "green" water and algal growths.

By all means contact Quest on the e-mail I gave above.

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GigHarborSurveyor
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@chris-mills

Thanks, I'll check it out. The current method used to inventory submerged, near-shore plant growth in fresh water lakes is to take a boat and throw out a rake and log the amount of plants, then move 10-20 feet away..rinse and repeat. For larger lakes, this is pretty time consuming and labor intensive method. I cannot help but think that some combination of imaging (possibly both under and over water) and GPS could replace this.

I recently looked into "green" LiDAR that penetrates water. From what I can tell, there are only 2 outfits that produce this for UAV's, one being the Bathycopter and the other a company out of Australia. Neither has a lease/rental program so you have to purchase. And at that, I have not checked to see if these sensors have returns that would make identifying plants feasible. By that I mean only return ground points. Moat of the bathymetric LiDAR sensors are made for traditional fixed or rotary wing platforms.

 

Sorry for the off topic rant, but I think this is an area of great revenue potential as in this state there is a requirement that these lakes have plant surveys every so many years and the old boat an rake method seems ripe for updating.

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chris mills
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@gigharborsurveyor

Not really off topic - we have done a couple of jobs to provide high resolution imagery to determine ground cover. The biggest problem to getting the technique widely adopted is that you deprive the ecologists of an excuse to wander around the countryside for days!

A combination of air, with a boat taken check samples at a much greater spacing might well suit your needs. You might also need to look at double coverage - once with conventional imagery and once with the multispectral.

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