DJI drones - New Mavic 2 pro announced tomorrow

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#83
DJI's new products are one step away from preventing this kind of thing, but that hardly matters. Homebrew stuff is really easy to build and operate.

Honestly, calling this a "drone" issue is misleading. This could have been done with RC airplanes decades ago. This is people doing stupid and malicious things, and will lead to laws that don't prevent anything.

Tip for any potential legislators: If the thing that is being done is already illegal (flying stuff around airports), passing laws that make it more illegal or illegal in a different way probably won't have the effect you are promising.
 

jtr1962

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#88
I wonder what is the terminal velocity when the power dies.
You can see the ascent/descent rate in the info screen (middle right just under the altitude). It looks like it maxed at around 37 m/s (83 mph) for the 33,000 foot flight and about 48 m/s (107 mph) for the 40,000+ foot flight. That slows a lot as you descend into thicker air. The propellers autorotate on the way down, slowing the descent rate dramatically. It looks like the pilot just lets the drone autorotate until it's a few hundred meters up, then applies power for a soft landing.

The temperature was interesting. I saw -53°C (-63°F) on the higher flight. That probably helps with motor efficiency but hinders battery efficiency. However, given the huge current draw, the battery probably self heats enough so the low temperatures aren't an issue.

It's amazing the guy who built the drones improved his record that dramatically. Who knows, maybe he'll break 50K eventually.
 

Handruin

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#90
When I watched the video I was paying most attention to the m/s velocity on the way up and the voltage. Originally I was wondering if this would be a sacrificial drone and just get it to altitude and run the battery empty. I'm impressed they kept it within reasonable location to the launch site. I figure dup that high they were fighting off some good winds with it being tilted quite a bit. If there were a legal location to do this in the US I think it would be neat to build one and try. Maybe with enough planning and FAA notification for a test like this it could be coordinated to do it safe in an unrestricted flight zone maybe somewhere in Utah/Arizona.
 

jtr1962

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#91
Those are my thoughts exactly, Doug. I would love to try something like this but it's obviously not happening in NYC, or probably anywhere in the NY Metro area, for obvious reasons. My parents bought a plot of land in New Mexico. It's pretty much in the middle of nowhere. The area was supposedly going to see development when they bought it in the 1970s but it's still scrub. The nearest developments are about 10 miles away. The nearest road is about 2 miles away. I've never been there, obviously, but it sounds like the perfect place for high altitude drone tests. It's 5,000 feet above sea level, so the drone already has a nice head start.

It looks like the pilot optimized the power level exactly so he would still have a little juice left after reaching maximum altitude. I noticed the power level was about 60% at the start, but that was gradually ramped up as the air got thinner. Then he just autorotated most of the way down, and saved what was left for a soft landing.

Another interesting thing with both videos is how the ascent was mostly steady right up until near the end. In both cases it looked like the drone had to claw up those last few hundred meters. I'm guessing with the higher flight he used a bigger prop to get more bite in the thin air. Just for reference the air density at 40,000 feet is only about 25% what it is at sea level.
 

Handruin

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#92
I may have used the wrong term earlier, I meant uncontrolled airspace in the USA. I don't know if this is a project we could ever try together but it might be neat to see if the record could be broken again in a legal way.
 

jtr1962

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#93
I may have used the wrong term earlier, I meant uncontrolled airspace in the USA. I don't know if this is a project we could ever try together but it might be neat to see if the record could be broken again in a legal way.
I've read it's possible to get waivers but that's probably beyond the means of hobbyists. Companies like Blue Origin have to get waivers to launch their rockets, for example.

It looks like there are no rules regarding height in Mexico, so that's one possibility:

https://www.uavsystemsinternational.com/drone-laws-by-country/mexico-drone-laws/

Canada has similar rules as the US:

https://www.uavsystemsinternational.com/drone-laws-by-country/canada-drone-laws/
 

LunarMist

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#94
You can see the ascent/descent rate in the info screen (middle right just under the altitude). It looks like it maxed at around 37 m/s (83 mph) for the 33,000 foot flight and about 48 m/s (107 mph) for the 40,000+ foot flight. That slows a lot as you descend into thicker air. The propellers autorotate on the way down, slowing the descent rate dramatically. It looks like the pilot just lets the drone autorotate until it's a few hundred meters up, then applies power for a soft landing.
But what happens when the power and controls are completely gone? I think it could fall faster than when auto-rotating, but maybe it would not make much difference. In any case I suspect that a few injuries and deaths could ensue in a public area. Starting from 40,000 miles up, the drone could land over a large area depending on the winds.
 

jtr1962

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#95
But what happens when the power and controls are completely gone? I think it could fall faster than when auto-rotating, but maybe it would not make much difference. In any case I suspect that a few injuries and deaths could ensue in a public area. Starting from 40,000 miles up, the drone could land over a large area depending on the winds.
That all may be true, but look where they're testing it. It's probably miles from anybody but the people testing it.

I also don't think it would fall a whole lot faster even not autorotating. It's light with a fairly large surface area. I'd be surprised if its terminal velocity at lower altitudes is much over 30 m/s. It weighs less than a kilo. Getting hit by it would probably hurt less than getting hit with a fast-pitched baseball.

The bottom line is that it probably won't hit the ground much faster falling from 40,000 feet than from the 400 feet which is legal to fly in the US. In fact, a person reaches terminal velocity after falling only about 1,500 feet. A lightweight drone will reach terminal velocity in a lot shorter distance.
 

Stereodude

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#96
I've been enjoying it. I haven't used it in a week or so, but I've spent time flying it just for fun at my local park. I've had no issues with it so far except one of the props had a crack in it and I don't know why. The package came with extras so it wasn't a big deal and I got even more when I bought the fly-more kit.
Have you been using your Mavic 2 Pro much? Made any cool videos?
 

Handruin

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#97
I haven't used it as much as I'd like to. I bought a house in March and a bunch of my time has been spent renovating parts of it and hosting events. I'm using it more this week having done fun. I can't claim I've made any cool videos with it. More just scenic stuff. Surprisingly I've used it multiple times to help people look at their roof to see what condition it's in... Myself included. :)
 

Handruin

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#98
I got some time today to play around a bit more. I woke up for sunrise and took some footage at the beach. Here is a still from a couple hundred feet up.

I also flew my Mavic 2 down the coast over a mile. I know it's capable of much further but it was a little anxiety producing. I had no issues with signal strength or operating it at that distance. DJI_0157.JPG
 

Handruin

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There isn't one available for this drone. You would need to consider a different model or something custom. How much flight time are you requiring?
 

Handruin

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It was a poor execution of sarcasm on my part. I assumed you were inferring I broke the rules because I lost sight of the drone but maybe you meant a different rule.
 
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