Energy of a falling drone (off topic posts extracted from another thread)

[moldorf]

it is a privilege to be able to fly a drone in public air-space. That privilege comes with responsibility. And maybe the first responsibility is to just analyze what it is you're doing. Maybe a basic review of physics?

I know enough about physics that I considered what it was when I flew my first drone, a Mini 2. Here's a basic: if your drone is 400 feet in the air and it suddenly loses power and falls, by the time it hits the ground it will be traveling over 100 miles an hour; about 109mph IIRC the formula correctly. That's over 48 meters/sec.

For a half pound drone, that's close to 300 joules and well over 200 foot-pounds of force. How much is that? Picture a 1 pound weight....then picture the amount of energy it would take to push that one pound weight over 200 feet. That's a little off as an analogy but it does convey the energy a mini drone would have, falling from 400 feet (assuming I have my physics about right)

at that velocity, it isn't a plastic object any more. It's a half-pound rock. Now, instead of a half-pound Mini, think about a 2 pound Mavic 3 falling from that distance. I sure did when I bought my Mavic 3. The reality is that's the liability you're accountable for when you fly a drone. If a Mavic 3 falls from 300-400 feet, it would be a 2 pound rock. Imagine that hitting the windshield of a moving car

irresponsible pilots are giving drones pilots a bad name and are the ones who are generating all the restrictions of flying drones

 

[Don Testme]

it is a privilege to be able to fly a drone in public air-space. That privilege comes with responsibility. And maybe the first responsibility is to just analyze what it is you're doing. Maybe a basic review of physics?

I know enough about physics that I considered what it was when I flew my first drone, a Mini 2. Here's a basic: if your drone is 400 feet in the air and it suddenly loses power and falls, by the time it hits the ground it will be traveling over 100 miles an hour; about 109mph IIRC the formula correctly. That's over 48 meters/sec.

For a half pound drone, that's close to 300 joules and well over 200 foot-pounds of force. How much is that? Picture a 1 pound weight....then picture the amount of energy it would take to push that one pound weight over 200 feet. That's a little off as an analogy but it does convey the energy a mini drone would have, falling from 400 feet (assuming I have my physics about right)

at that velocity, it isn't a plastic object any more. It's a half-pound rock. Now, instead of a half-pound Mini, think about a 2 pound Mavic 3 falling from that distance. I sure did when I bought my Mavic 3. The reality is that's the liability you're accountable for when you fly a drone. If a Mavic 3 falls from 300-400 feet, it would be a 2 pound rock. Imagine that hitting the windshield of a moving car

irresponsible pilots are giving drones pilots a bad name and are the ones who are generating all the restrictions of flying drones

Do your calculations take into account wind resistance/ friction on the drone. The shape of the drone and its props will slow it down considerably. Wind updrafts may also come into play. For example: a paper plane thrown from 400 ft may actually go up rather than down.

Your calculations are probably good for dropping a smooth rock. But a drone's shape and props and it flipping over and over in the air will slow it down.

I actually crashed a mavic 2 pro on a housing unit once from 500ft (yep, too high). It simply bounced off, broke into pieces and didn't even dent the roof of the house.

I DO ADMITTEDLY STAY AWAY FROM AIRPORTS. Especially their flight corridors for landing and taking off.

 

[moldorf]

Do your calculations take into account wind resistance/ friction on the drone. The shape of the drone and its props will slow it down considerably. Wind updrafts may also come into play. For example: a paper plane thrown from 400 ft may actually go up rather than down.

Your calculations are probably good for dropping a smooth rock. But a drone's shape and props and it flipping over and over in the air will slow it down.

I actually crashed a mavic 2 pro on a housing unit once from 500ft (yep, too high). It simply bounced off, broke into pieces and didn't even dent the roof of the house.

I DO ADMITTEDLY STAY AWAY FROM AIRPORTS. Especially their flight corridors for landing and taking off.

sure...I'd imagine it's less than the 109MPH

but if it's only 70MPH does that really make a difference? especially with a 2 pound drone?

 

[Don Testme]

sure...I'd imagine it's less than the 109MPH

but if it's only 70MPH does that really make a difference? especially with a 2 pound drone?

2 lbs. Probably not. But I guess it also depends on what it hits. I certainly hope it doesn't hit a moving vehicle or pedestrian . That would be horrible.

Maybe someone should invent a parachute ejection system for drones. If the drone is out of control, the parachute launches bringing the drone down slow. Make the parachute orange so retrieval would be easier. How would the parachute device know the drone is out of control though? I guess we could leave that up to the software programmers.

 

[MA2 317]

Maybe someone should invent a parachute ejection system for drones.

How about this item?




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[MAvic_South_Oz]

I know enough about physics that I considered what it was when I flew my first drone, a Mini 2. Here's a basic: if your drone is 400 feet in the air and it suddenly loses power and falls, by the time it hits the ground it will be traveling over 100 miles an hour; about 109mph IIRC the formula correctly. That's over 48 meters/sec.

Falling objects are very much affected by other factors.

Yeah it'd still be bad hitting a human or other property.

 

[Don Testme]

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How about this item?


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Does it eject the parachute when the drone loses remote contact and is falling uncontrollably? it costs too much though.

 

[Ty Pilot]

Speed of a falling drone has been discussed quite a bit and a drone the size of a Phantom, generally maxes out at 12 to 16 meters per second or around 27 to 35 MPH. Still wouldn't want to be hit by one falling though.

 

[Don Testme]

Speed of a falling drone has been discussed quite a bit and a drone the size of a Phantom, generally maxes out at 12 to 16 meters per second or around 27 to 35 MPH. Still wouldn't want to be hit by one falling though.

HAH ! I knew it would fall a lot slower than what our physics professor described.

 

[MAvic_South_Oz]

Does it eject the parachute when the drone loses remote contact and is falling uncontrollably? it costs too much though.

They deploy when sensors in the unit detect certain parameters.
There are units of varying costs, many would be within certain commercial pilots price point.

 

[sar104]

HAH ! I knew it would fall a lot slower than what our physics professor described.

The terminal velocity of a Mavic-type aircraft is around 45 mph.

The Terminal Velocity of a Falling Mavic 2

First second it travels 16' but in that one second it has accelerated to 32 FPS. (Starts at 0 FPS, accelerates to 32FPS, and thus averages 16FPS for the first second.) It travels 48' in the second second, and accelerates from 32FPS to 64FPS, and so on.

mavicpilots.com

 

[moldorf]

The terminal velocity of a Mavic-type aircraft is around 45 mph.

yeah, I was way off in my physics assumptions

still, a 2 pound drone traveling at 45mph would translate to around 183 joules or 135 foot-pounds.. That would very likely be a fatal impact on a person if it was the head or chest

60 foot-pounds will shatter a windshield

 

[123taff]

Why are we arguing among ourselves the differences in forces between a rock and a drone falling out of the sky?? Does it really make any difference?

The potential for harm to anyone going about their business on the ground suddenly being struck by a silent, out of control drone falling on them is enough for the authorities to legislate to control that potential.

Yes a drone isn't going to do the same damage to a person or structure as a rock falling, but a drone suddenly striking a windscreen of a car "might" cause a panic that results in the driver losing control and causing a collision.

Besides which, the likely hood of a rock falling out of the sky from 400 feet is much less than a drone purposely flown above their heads in an urban setting.

It seems as though some cannot grasp the reality that our hobby is heavily regulated for a reason, and no amount of protest from us or the non acceptance of that reality is going to make it any easier going forward.

It seems to me that rather than complaining that other sections of society get away without such regulation, and making pointless comparisons between disciplines, we should be concentrating on the positives of our own chosen hobby, and work with the authorities to ensure the safe continuation of our past time!

 

[Mountainman75]

2 lbs. Probably not. But I guess it also depends on what it hits. I certainly hope it doesn't hit a moving vehicle or pedestrian . That would be horrible.

Maybe someone should invent a parachute ejection system for drones. If the drone is out of control, the parachute launches bringing the drone down slow. Make the parachute orange so retrieval would be easier. How would the parachute device know the drone is out of control though? I guess we could leave that up to the software programmers.

Threre is many parachute recovery systems for drones. The problem is they often cost more than the drone, especially for consumer drones like the Mavic series, so no one buys them. How they can justify the cost of these recovery systems is beyond me. They have maybe a few hundred worth of material and software and they charge thousands to buy.

 

[Don Testme]

Threre is many parachute recovery systems for drones. The problem is they often cost more than the drone, especially for consumer drones like the Mavic series, so no one buys them. How they can justify the cost of these recovery systems is beyond me. They have maybe a few hundred worth of material and software and they charge thousands to buy.

Here is an automatic parachute ejection system for under 90 dollars. Apparently they have come down in price significantly. This one (sold by walmart) detects if the drone is falling too fast or if it topples or turns abnormally as in any malfunctioning drone. Then the chute is ejected as soon as it detects it is safe to eject the chute without getting itself caught in the props or other parts of the drone.

Here is the link: Robot or human?

 

[123taff]

Be careful what you wish for.
A Parachute recovery system might well be ideal for an Air or Mavic or above, but only as an additional system for a flyers complete peace of mind should the Drone malfunction and drop out of the sky, to save the drone from damage and the inevitable cost of replacement.

BUT, is there a suggestion that such systems should be a legal requirement to all drone flying?

That would be as much damaging to hobby drone flyers as any further legal constraints on flying.
The reason would be that, certainly in the UK, a parachute recovery system added to a sub 250G drone like our Mini 2s and 3s would put them over the weight for the lesser restrictions enjoyed by sub 250 drone flyers.
That would kill the hobby dead for many enthusiasts.

 

[Don Testme]

Be careful what you wish for.
A Parachute recovery system might well be ideal for an Air or Mavic or above, but only as an additional system for a flyers complete peace of mind should the Drone malfunction and drop out of the sky, to save the drone from damage and the inevitable cost of replacement.

BUT, is there a suggestion that such systems should be a legal requirement to all drone flying?

That would be as much damaging to hobby drone flyers as any further legal constraints on flying.
The reason would be that, certainly in the UK, a parachute recovery system added to a sub 250G drone like our Mini 2s and 3s would put them over the weight for the lesser restrictions enjoyed by sub 250 drone flyers.
That would kill the hobby dead for many enthusiasts.

I understand a parachute system would increase the weight . No one would want them required. But the people who made those weight laws were considering the pounds per square inch if the drone hit a person or object during the drone's free fall.

If that's the case, if a drone was parachute equipped, law makers would be able to increase the weight limit of the smaller drones to keep them in the same safety class they are currently in. If a parachute were released, the pounds per square inch upon impact, with a parachute deployed, would drop many fold. This would allow law makers to increase the weight restrictions. That's my opinion anyway.

 

[MAvic_South_Oz]

BUT, is there a suggestion that such systems should be a legal requirement to all drone flying?

Perhaps mainly for commercial type flights where one has permission to fly over people / crowds / property.
Obviously legislation is probably required to allow such flights with certain safety measures.
A parachute recovery system, and probably propeller cages or ducted props would possibly be two of those measures.

 

[SethB]

Be careful what you wish for.
A Parachute recovery system might well be ideal for an Air or Mavic or above, but only as an additional system for a flyers complete peace of mind should the Drone malfunction and drop out of the sky, to save the drone from damage and the inevitable cost of replacement.

BUT, is there a suggestion that such systems should be a legal requirement to all drone flying?

That would be as much damaging to hobby drone flyers as any further legal constraints on flying.
The reason would be that, certainly in the UK, a parachute recovery system added to a sub 250G drone like our Mini 2s and 3s would put them over the weight for the lesser restrictions enjoyed by sub 250 drone flyers.
That would kill the hobby dead for many enthusiasts.

Operations Over People (OOP) is a new regulatory area enabled in the USA by Congress and enacted in rules/regs as of April 2021.

FAA’s overview is here:

Operations Over People General Overview | Federal Aviation Administration

The Operation of Unmanned Aircraft Systems Over People final rule is the next incremental step towards further integration of unmanned aircraft (UA) in the National Airspace System. The final rule allows routine operations over people and routine operations at night under certain circumstances...

www.faa.gov

A sub-250g drone comes in below the max impact spec for Category 1, but it must not lacerate the skin. The Mini 2 has been tested out by a few people by adding a prop guard, removing some prop guard structure to reduce weight, and using a lighter battery to keep it under 250g to conform to Cat 1.

It’s manufacturer’s certification and FAA acceptance for Cat 2 & 3 drones. It would involve stopping the props (laceration) and parachute (impact).

That FAA has implemented this means, I think, at least in the USA, that we are not facing parachute requirements for all drones. Only those drones set up for legal operations over people.

 

[Mountainman75]

Here is an automatic parachute ejection system for under 90 dollars. Apparently they have come down in price significantly. This one (sold by walmart) detects if the drone is falling too fast or if it topples or turns abnormally as in any malfunctioning drone. Then the chute is ejected as soon as it detects it is safe to eject the chute without getting itself caught in the props or other parts of the drone.

Here is the link: Robot or human?

They do look promising but the Walmart parachutes don't meet the Safety Assurance standards set out by Transport Canada and FAA to allow flight "over people". I would never put on a no-name chute that detects falling during regular drone flight, even the approved chutes have been know to go off accidentally during vigorous flight causing the chute to get caught up in the drone props and it falls like a rock anyways because the chute doesn't deploy properly.