Lost a blade at 100 feet up...

[black_magic100]

Fixed wing aircraft can fly with fewer than all engines because the engines only provide thrust, not lift or aerodynamic stability. With multicopters the propellers are the wings, and while it's not completely analogous to expecting a fixed-wing aircraft to fly with only one wing, the problem is similar. In principle a quad can fly with just three rotors, with primary lift being provided by the two remaining diagonally opposed can counter-spinning rotors and rotation around the axis connecting them being controlled by the third motor. That's unbalanced in terms of angular momentum around the vertical axis, leading to a lack of yaw control (you can live with that), but it also likely requires the third motor to be reversible in order to be able to provide up or down thrust.

Makes sense. Thank you for clarifying.

 

[AnzacJack]

I'm not saying it's 100% true! I honestly have no idea if it's possible. However, somebody else in the thread linked a video and it appears to not work so looks like you are indeed correct!

As far as 750,000 lb planes go... https://www.google.com/search?q=are...rome..69i57.6583j0j9&sourceid=chrome&ie=UTF-8

Their is a quick google search and the first result. Most modern airplanes today are designed to run on a single engine. Obviously some planes/small jets only have one engine, in which case you are most likely going to die .

Sure , heavy planes can fly on one engine, as the engine is not the component supplying lift (generAlly speaking). However there is a big difference between a 750,000 tones and 750, 000 lbs....

If I where you, I’d stick with not making claims you are not sure about

 

[black_magic100]

Sure , heavy planes can fly on one engine, as the engine is not the component supplying lift (generAlly speaking). However there is a big difference between a 750,000 tones and 750, 000 lbs....

If I where you, I’d stick with not making claims you are not sure about

Meant to say lbs, not tons as I googled this https://www.google.com/search?q=how.....69i57j0l5.4006j0j7&sourceid=chrome&ie=UTF-8

I am just going off google my friend. I am not "making claims". I said that most modern day airplanes are built to run on only one engine, which is true as per your statement. Regardless, I really don't care at this point as the entire conversation began with the discussion about whether the mavic pro could safely land after losing a propeller and it appears to be false. Somehow my words are being twisted and I don't appreciate it. In fact, my original statement that started this whole fiasco included "I heard a rumor... Not sure how true it is". Perhaps this should have stopped after somebody else immediately replied with "not true at all", to which I replied by admitting I was wrong. You can clearly see that in my original statements I expressed uncertainty on the topic and never had the intention that what I was saying should come across as fact.

 

[AnzacJack]

Not sure why you guys are acting like it is some voodoo magic. Billion dollar airplanes that weigh 750,000 tons are designed to run off single engines. There are many quads that can also safely land with 3 props.

Ok let’s leave it at that. But don’t accuse people of twisting your words. The above quote is plainly stated by you, and it is plainly wrong.
And don’t use the defence of what you “meant” to say. I can only respond to what you “do” say as I can’t read your mind

 

[black_magic100]

Ok let’s leave it at that. But don’t accuse people of twisting your words. The above quote is plainly stated by you, and it is plainly wrong.
And don’t use the defence of what you “meant” to say. I can only respond to what you “do” say as I can’t read your mind

video proof of quad copter flying/landing safely with 3 props in 2013:

Granted it was in a controlled environment, but it still is possible and keep in mind that this was 2013. My statement is indeed 100% correct.

 

[AnzacJack]

You said there are many quads that can land with 3 props.
What you are showing is one that has been specifically programmed as a test platform. Yes I have seen these, but I don’t think it’s what you were getting at.
If you believe what you said was 100% correct then so be it.

 

[radial]

I lost an entire prop when I was about 50' up. Popped right off and fell to the ground. The Mavic flew like a drunken sailor, but it descended under some semblance of control and landed upright. Broke one of the other props because it came down at an angle, but no big deal. I bet the DJI firmware could be enhanced to detect this condition and compensate for it, but that's just ignorant me speculating.

 

[AnzacJack]

I lost an entire prop when I was about 50' up. Popped right off and fell to the ground. The Mavic flew like a drunken sailor, but it descended under some semblance of control and landed upright. Broke one of the other props because it came down at an angle, but no big deal. I bet the DJI firmware could be enhanced to detect this condition and compensate for it, but that's just ignorant me speculating.

I’d like to see that,
We need someone to do some “blade off” testing

It would be simple for the firmware to detect to condition as it should be easy to interpret an motor speeding up significantly and a loss of lift on that arm

 

[black_magic100]

You said there are many quads that can land with 3 props.
What you are showing is one that has been specifically programmed as a test platform. Yes I have seen these, but I don’t think it’s what you were getting at.
If you believe what you said was 100% correct then so be it.

Specifically programmed maybe, but whose to say that the mavic couldn't be specifically programmed to do that exact same thing? This drone shown here flies normally and is a quad; it doesn't have any extra hidden propeller.

Why are you saying that's not what I was originally thinking? How do you know what I am thinking? That is exactly what I was thinking. A controlled descent by the mavic if a propeller is lost. I had no expectations that you could fully control it with only 3 props the same as if it had 4.

I think this conversation can be summed up by saying two things...

1) the mavic appears to not be able to make a controlled descent at the loss of a prop while airborn

&

2) it is 'realistically possible' for a quadcopter similar to the mavic to be able to be programmed to make a controlled descent, but not guaranteed that the mavic itself has that ability based on other variables

If you can't agree with those two statements then I give up.

 

[AnzacJack]

Then name some of these many quads that can do this

You make absolute statements then defend them by saying we are twisting your words.
You are now defending that you are correct about the many quads that can land safely with 3 blades. I am saying you are wrong. But I’m happy to admit I’m wrong if you can name some other than a lab experiment.

What you said in your last post is right, and I don’t refute that. I’m only saying your previous statements where wrong.

Although from what Radial is saying, perhaps the mavic can recover with a missing blade from 50’

 

[black_magic100]

Then name some of these many quads that can do this

You make absolute statements then defend them by saying we are twisting your words.
You are now defending that you are correct about the many quads that can land safely with 3 blades. I am saying you are wrong. But I’m happy to admit I’m wrong if you can name some other than a lab experiment.

What you said in your last post is right, and I don’t refute that. I’m only saying your previous statements where wrong.

Although from what Radial is saying, perhaps the mavic can recover with a missing blade from 50’

Yea man I give up trying to convince you honestly. You need to do your own research because anything I say or provide you with you will just refute. I'm not going to spend hours trying to find every quad that can potentially recover from a missing blade or either ones that are specifically programmed to do so. I strongly encourage you to just Google and read through several forum posts and hopefully you will find what you are looking for; whatever that may be. Cheers!

 

[radial]

Although from what Radial is saying, perhaps the mavic can recover with a missing blade from 50’

"Recover" might be overstating the case, but I was able to bring it down at a rate of descent that ensured a fairly soft landing. It landed on an asphalt roadway and only sustained any damage at all because it wasn't level when it touched down. Somebody with money to burn really should run some tests.

 

[AnzacJack]

Yea man I give up trying to convince you honestly. You need to do your own research because anything I say or provide you with you will just refute. I'm not going to spend hours trying to find every quad that can potentially recover from a missing blade or either ones that are specifically programmed to do so. I strongly encourage you to just Google and read through several forum posts and hopefully you will find what you are looking for; whatever that may be. Cheers!

i dont need to google it. I work closely with industry and tech in this field and know what capabilities of the systems are. you just cant admit you were wrong in that statement. You readily acknowledge you dont have any depth of knowledge yet refuse to admit that your statement about there being many quads that can recover was just something you said of the top of your head. Like the aircraft weight that you later corrected.
The only reason i have pursued you on this was because of your smug comment about this not being voodoo

(Not sure why you guys are acting like it is some voodoo magic. Billion dollar airplanes that weigh 750,000 tons are designed to run off single engines. There are many quads that can also safely land with 3 props. )

anyway, it seems you like to be the one to have the last say so ill leave you to your next comment and move on

"Recover" might be overstating the case, but I was able to bring it down at a rate of descent that ensured a fairly soft landing. It landed on an asphalt roadway and only sustained any damage at all because it wasn't level when it touched down.

thats still better than i would have thought possible.

 

[dirkclod]

If you 2 want to have a go at each other than please do so in a conversation
and let's get this back to the original members issue .
This has done went off topic and does stop here .
Thanks.

ADDED / Please stay on the topic of the oringal post and nothing else .

 

[lexustbs]

Unless the drone has a complex flight algorithm that

1. Understands what has happened, which prop has come loose
2. Then applies asymmetrical thrust on the other three fans
3. Gimbals and acceletomoter are fast enough to send correct signals

Then a three prop drone is coming to the ground in quick order. Does not matter how you move the sticks, the human eye plus the inability to control each motor, this thing is crashing.

There is software and drones out there in very limited prototypes that can "land" when a prop gets lost, but if you watch the videos even then the drone is in a controlled state of crashing.



I found this video to show the issue. The side that the blade come off on just drops.