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FAA Category 2 and 3 Explored... What is 11ft/lbs of kinetic energy???

joeywestside

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So I'm trying to understand what kinetic energy of 11 ft/lbs and 25 ft/lbs.... Here's what I can't up with for a Mavic Air 2 at 1.3lbs... (I'm not a physicist btw).

11 ft/lbs is 14.9 joules. 1.3lbs at a velocity of 16mph is 15.1 joules.

25 ft/lbs is 33.9 joules. 1.3lbs at a velocity of 24mph is 33.9 joules.

So... Crashing into a person at 16mph is a Category 2 event, yes?

And crashing into someone at >16 but
But is the FAA talking about a freefall event?
In which case, 1.3lbs falling from 400ft reaches 109mph, which would be 700 joules or 516 ft/lbs.
Obviously this is a freefall and a drone has a significant amount of drag so it would fall slower (sorry, I don't have data for how fast a MA2 freefalls).

Pilots, please chime in.
 
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There's a YouTube video of a Mavic Pro in which the pilot kills the props and feel 4,000ft before recovering for a safe landing...

Upon watching the video, the fall speed is 11mph peaking at maybe 15mph....


So, your thoughts?
 
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Just three
1. Illegal altitude in the video.
2. Your calculations don’t allow for wind resistance/tumbling and 32ft/sec/sec is acceleration of gravity on any object.
3. If flying legally and safely it doesn’t matter.
 
2. Your calculations don’t allow for wind resistance/tumbling and 32ft/sec/sec is acceleration of gravity on any object.
32 ft/sec/sec is the hypothetical acceleration due to gravity they teach you in school.
But to achieve that the body has to be falling in a vacuum.
Air resistance makes a big difference in real world situations.
DJI drones reach a terminal velocity that's much lower than you'd expect.
I haven't seen evidence for an Air 2 but other larger DJI drones, it's about 35-38 mph (15-17 metres/sec) and varies if the drone tumbles.
 
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So... Crashing into a person at 16mph is a Category 2 event, yes?
The formula for Kinetic Energy of a moving object is KE = 1/2 MV²
A DJI Air 2 weighing 0.570 Kg crashing into something at 16mph (7.15 metres/sec) has a KE of 14.6 Joules or 10.75 Ft Lbs
(Doing calculations like this makes you really appreciate the metric system)

And crashing into someone at >16 but
But is the FAA talking about a freefall event?
In which case, 1.3lbs falling from 400ft reaches 109mph, which would be 700 joules or 516 ft/lbs.
Obviously this is a freefall and a drone has a significant amount of drag so it would fall slower (sorry, I don't have data for how fast a MA2 freefalls).
See above for an explanation of why freefall velocity is much less.
A DJI Air 2 weighing 0.570 Kg, falling at 16 metres/sec has a kinetic energy of 72 joules or 53 Ft Lbs.
 
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Wait! So.... Is the FAA basing their figure on horizontal flight speed, or freefall speed? Is the Mavic Air 2 a category 2 or a category 3 drone for flying over people?
 
Wait! So.... Is the FAA basing their figure on horizontal flight speed, or freefall speed? Is the Mavic Air 2 a category 2 or a category 3 drone for flying over people?
I haven't seen and don't know what the FAA is asking.
I just did the maths to answer the questions you asked.
 
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The implication is that you will need to have some type of system(parachute), to slow it down to a descent speed which will fall within the requirements. If you are too low, a parachute won’t have enough distance to deploy.
 
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Here's what I can't up with for a Mavic Air 2 at 1.3lbs...
The other issue is that it would not fall under any category, it's uncategorized just like most of the current drones DJI makes including the Air 2s, mini, mini 2, mini 3 pro, etc etc.

So in regards to the rule of flying over open air assembly, even with a prop guard. Due to being uncategorized drones, they still can't fly over people according to the FAA period. DJI has to submit approval for each model to be categorized and so far the only approval they got was for Remote ID, not for categorization.

In short, doesn't matter how much force a Mavic Air 2 would cause, because you won't be able to fly over anyways without that categorization officially approved and labeled.
 
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There's also the momentum that builds up. For a 2 lb object the momentum is pretty impressive. The aerodynamic drag feature is holding on to it, there's no tires on the pavement slowing it down, almost like a hovercraft.
 
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None of this matters if we ban gravity. Join the cause...
 
There's also the momentum that builds up. For a 2 lb object the momentum is pretty impressive.
What does that mean? Does it mean anything?
The FAA is interested in kinetic energy, not momemtum.
 
What they are attempting to do with the ratings is come up with a compromise to allow drones to be used in ways they could not in the past. Once Remote ID is implemented, the classifications 2-4 will come into play and honestly who knows which of 2 or 3 would apply. The answer would come more from the person hit by the drone. Did it feel like a light contact, moderate, or did it smash you and hurt and to what degree. You’re never going to be allowed to hit someone with say 10ft lbs and say well, it was less than 11. The definitions really aim to describe someone being hit by an octa carrying a Red vs a compact drone. It’s not Air 2 vs Mavic 3 so much, both would be roughly in the same category and in all cases you should avoid sustained flight over people even when permitted.
 
What they are attempting to do with the ratings is come up with a compromise to allow drones to be used in ways they could not in the past. Once Remote ID is implemented, the classifications 2-4 will come into play and honestly who knows which of 2 or 3 would apply. The answer would come more from the person hit by the drone. Did it feel like a light contact, moderate, or did it smash you and hurt and to what degree. You’re never going to be allowed to hit someone with say 10ft lbs and say well, it was less than 11. The definitions really aim to describe someone being hit by an octa carrying a Red vs a compact drone. It’s not Air 2 vs Mavic 3 so much, both would be roughly in the same category and in all cases you should avoid sustained flight over people even when permitted.
It's all moot if dji doesn't send documentation to the FAA to be approved. They did remote id because they must. But unless dji gets approval to classify them, they can't fly over people at all as they're uncategorized.
 
It's all moot if dji doesn't send documentation to the FAA to be approved. They did remote id because they must. But unless dji gets approval to classify them, they can't fly over people at all as they're uncategorized.
Maybe I’m optimistic but my guess is DJI is first in line each time something comes up related so not to prevent lost sales. :)
 
Maybe I’m optimistic but my guess is DJI is first in line each time something comes up related so not to prevent lost sales. :)
Perhaps. But they only just now put class 1 on the Mavic 3 classic over in EU (which isn't the same thing as category 1 in the US). So they feel behind but I don't know if autel etc are doing any better about it.
 
What does that mean? Does it mean anything?
The FAA is interested in kinetic energy, not momemtum.
There was a 15 quad pileup.

And nobody got hurt.

Not sure how they can guarantee any of that. Several variables can and will be involved at any given moment, maybe it shattered into a million pieces and then fell on somebody.

crash-testing-dummies1.jpg
 
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