Flying with a disabled prop or motor (P4P)

[Kristina Fowler]

A prospective industrial client who is uber-concerned about safety asked me a question on the topic of "redundancy". Specifically, he wanted to know if a P4P collided with an object and lost or damaged a prop or motor, could it still be controlled with the remaining 3 props/motors. I had to plead ignorance on this.

Does anyone have any first-hand experience on this? Thanks in advance for sharing your experience.

KF

 

[sswingle]

Basically no. You’ll hear a story here and there where someone managed to land with three but in most cases you’ll fall out of the sky like a rock.

 

[msinger]

The P4P definitely cannot fly with only 3 props. It'll drop like a rock for sure.

 

[tcope]

It will end up doing barrel rolls as it plummets to the ground.

1:02 mark:

 

[Meta4]

A prospective industrial client who is uber-concerned about safety asked me a question on the topic of "redundancy". Specifically, he wanted to know if a P4P collided with an object and lost or damaged a prop or motor, could it still be controlled with the remaining 3 props/motors.

Steer your client away by explaining how the obstacle avoidance sensors work to prevent collisions.

 

[Kristina Fowler]

Steer your client away by explaining how the obstacle avoidance sensors work to prevent collisions.

Oh I did for sure. However, the industry that he’s in is so off the charts with safety procedures that he still wanted to know.

 

[Meta4]

Oh I did for sure. However, the industry that he’s in is so off the charts with safety procedures that he still wanted to know.

If a Phantom loses the tip of a prop, it can come down safely but like msinger said, there is no way a Phantom can do anything but spiral into the ground if it loses a prop.
Prevention is the most effective safety measure. How close to obstacles would you have to fly?
If you can stay in the clear, there's nothing to worry about.

 

[WV. Rootman]

Tell them if the steering goes out in one of their vehicle will it crash? If a NASA rocket loses an engine on take off will it crash? That won't get you anywhere. Get proof of the drone's safety records above the other drones on the market. Show DJI's is the leader in the industry market. Show DJI redundancy built into the drone. Show what they are asking for is going to cost them a whole lot more.

 

[BigAl07]

For redundancy they need to look into a HEX or OCTO configuration instead of a QUAD configuration. The cost of operation goes up exponentially (more motors = more batteries etc) but safely is increased.

 

[Pharm]

Hi Kristina. No first hand experience necessary for this question. Theoretically, it would be possible to design a quad that could fly with one motor out but it would be difficult. If you think about how the motors work to maintain level, turn, etc. you’ll see how difficult this would be.

 

[BigAl07]

Hi Kristina. No first hand experience necessary for this question. Theoretically, it would be possible to design a quad that could fly with one motor out but it would be difficult. If you think about how the motors work to maintain level, turn, etc. you’ll see how difficult this would be.

I've seen some "Custom/Experimental" Quad UAS that could land safely (not maintain flight but a controlled landing) on 3 motors but for some reason this "Logic" is not built into the off-the-shelf flight controllers.

 

[WV. Rootman]

If you check into similar priced drones that have more motors for safety, they have many other safety issues, such as fly aways. Over all i think DJI is the safest drone.

 

[CianMcLiam]

You could just fit prop guards, show them the video on Tom’s Tech Time where he flies the Phantom 4 into walls and glass after fitting them. A hex or Octo has more redundancy but if it bounced off a wall you would more than likely lose at least two or more motors. You would also need battery redundancy so you could end up spending thousands and thousands.

 

[With The Birds]

The implementation of flight control algorithms have been demonstrated that will allow a quadcopter that has lost a prop/motor to be flown to a safe landing site. A constant yaw is introduced while constantly modifying the commanded stick inputs to provide for lateral movements. We know no such feature has been employed in the phantoms from the numerous crash incidents reported where prop/propulsion failure is evident. They all end the same way.

 

[syotr]

A prospective industrial client who is uber-concerned about safety asked me a question on the topic of "redundancy". Specifically, he wanted to know if a P4P collided with an object and lost or damaged a prop or motor, could it still be controlled with the remaining 3 props/motors. I had to plead ignorance on this.

Does anyone have any first-hand experience on this? Thanks in advance for sharing your experience.

KF

As others have said, there is no commercially available quad that will safely land after a motor or prop loss. I do have a Typhoon H hexcopter that will fly and safely land after loss of one rotor.

 

[John Locke]

Flying with only three motors is done all the time in other drones. DJI just hasn't incorporated that capability into the phantom firmware and flight controller yet. Theoretically it seems possible. Maybe that's coming in Phantom 5.

We can only hope.

 

[With The Birds]

Flying with only three motors is done all the time in other drones. DJI just hasn't incorporated that capability into the phantom firmware and flight controller yet. Theoretically it seems possible. Maybe that's coming in Phantom 5.

We can only hope.

It has been clearly demonstrated as possible- I haven’t been able to find where it has been implemented in a mainstream AC though- can you please provide an example?

 

[John Locke]

It has been clearly demonstrated as possible- I haven’t been able to find where it has been implemented in a mainstream AC though- can you please provide an example?

Search the FLIGHTTEST.COM list of YouTube videos, they've demonstrated three motor drones.

 

[With The Birds]

Search the FLIGHTTEST.COM list of YouTube videos, they've demonstrated three motor drones.

Thank you- I had seen those, they are designed as three rotor (tricopter) AC though so we would expect them to fly on three. What I haven’t seen is a quadcopter offered for mass market that claims to, or has been demonstrated as able to, continue flying with a single propulsion system failure.

 

[John Locke]

Thank you- I had seen those, they are designed as three rotor (tricopter) AC though so we would expect them to fly on three. What I haven’t seen is a quadcopter offered for mass market that claims to, or has been demonstrated as able to, continue flying with a single propulsion system failure.

That's correct, no reason DJI couldn't make it work if their engineering dept were given the task to figure it out. Seems very doable.