Safe speed to avoid motor cracks?

[solentlife]

I can only speak based on plastic ones I 3D printed - which were exact as per the templates but did not fit.

I have alloy plates on my P3S and my P3P ... they fit exact without any error at all.

These are the ones I fitted .... (but there are many sellers on Ebay with same ... )

4Pcs Metal Motor Protect Mount Base RC Quadcopter Kit for DJI Phantom 3 | eBay

One thing I like - the plates come with screws that use commonly available tools instead of star drivers etc. as DJI use.

Now points that are very important :

1. Stock screws for motor are short and MUST be saved in case you ever remove the plates. The plates supply slightly longer screws to compensate for the plate thickness.
2. You must use the tube standoffs with the two thinner screws at inner end .. this supports and locks shells
3. Get plastic safe BLUE Threadlock and use it to secure motor screws.

Myths that are ****** :

1. Extra weight causes cracks ..... that's pure rubbish and not true.
2. Extra weight shortens flight time .... if you are flying to max time on a P - then you are risking it anyway - but the plates actually are so light as to make literally no difference to flight times or flight itself

Thats my 2c worth anyway ..

Nigel

 

[JamesT1950]

I have over 200 flights on my P3A. I do hard braking and maneuvers. When I first bought my quad, I also bought the quick disconnect prop protectors. With these on the quad, I believe they give it more support around the motors which may be keeping it from cracking. Whether I actually use the protectors when I fly or not, the mounts are always in place. If anyone else uses these and still has cracking then I guess my theory is out the window.

 

[jeffcutler]

Where should I look for this cracking? I've had my P3S for three weeks and don't know if I have any cracking. But I land it like a feather and don't push it too hard. Here's my latest journey - today in 33° temps and 15mph winds. Flew it low to keep it stable and safe. Video is merely one minute and ten seconds long...enjoy!

 

[Meta4]

seems to be a lot of this about lately

There's also a lot of talk about shark attacks although they are very rare.

All this talk, mostly from people that never get any cracking but get scared and add to threads like this, only contributes to the perception that it is more common than it actually is.

even see one pic where a motor came out of the frame in flight due to this

I remember one like that ... and only that one.
It was about two years ago. Is it the same one?

 

[Meta4]

But according to some - its a rare item to see .....

Yeh well ... it may be only a small % of total P's sold - but its still too many ......... but considering I know of 10 P's that have cracked out of 10 I personally know of ... seems not so small a problem.

Yes... when you concentrate on a small number and talk it up and think of nothing else and convince others who join in like on this thread, it seems to be a big problem.
But if you look at actual numbers and the rate of cracking incidents and the proportion of Phantoms that never develop any cracking, it just doesn't stand up.
Is there a factor that might explain the number you've seen among your friends. Did many of them buy from the same source around the same time?

When you don't know the cause of an action or make assumptions that may not be true and take precautions based on invalid assumptions, you are generally wasting your time.
It's the kind of thinking behind sacrificing an animal to ensure a good harvest ... better to be safe than sorry.

It makes a lot more sense to find out how big the problem is and the actual cause of the problem and address that.
The facts are that many of the assumed causes like flight speed, hard turning or braking, poor design, prop balance etc are not valid as is shown by the number of flyers who fly without a care and never see cracking.
The explanation that best fits the evidence is that a small proportion of shells develop cracking because of poor materials and/or moulding technique.

And it's threads like this that add to the false perception and make owners think their Phantom will inevitably develop cracking even though the majority never will.
There are well over a million Phantoms out in the wild. If 10000 developed cracking, that would still be less than 1%.
And if you were unlucky enough to get one of those unlucky shells, DJI replace them under warranty or it's fairly easy and cheap to do it yourself.

 

[N017RW]

What M4 said.
I realize these are expensive toys but they’re not durable goods. If the past is any indication after about 3 years from introduction DJI will drop support (batteries) and you’ll need to look for remaining parts inventories and third-party suppliers for such.
Fly it , enjoy it, but know it’s not meant to last forever and by then you’ll likely have moved on or be flying something else.

 

[NCRichard]

I'm wondering if there is a relationship between flying speed and motor mount cracking.
Any suggestions on what constitutes safe vs aggressive flight?
Its not unusual for me to fly 20-25 mph with rare instances up to 30mph. I try not to make sudden turns or hard braking at those speeds. At slower speeds there are times I'll let go of the sticks if I've lost sight of the P3 or get disoriented. I know that brings it to a quick stop but am not sure that would be considered "hard braking".

Ive got a few cracks rebalance props helps I use model car glue seems to hold crack I dont hot dog strictly video but fighting wind sudden stops all stress plus they r not real aerodynamic.

 

[Henry Matias]

What he said...

Having worked in a plastics factory and having studied materials as part of my education, plastics are funny things. You could have something well made, with well mixed, good quality plastic that breaks really easily, and really poor low quality plastic that lasts forever.

There are too many variables to say which is good/bad.

For me at least, the most prominent variable is vibration. The motors themselves do not produce any significant vibration, higher frequencies will just get absorbed into the chassis, it's the low frequency vibrations caused by unbalanced propellers that will inevitably cause cracks.

I never used to balance props, but after seeing what happened to one of my birds without balanced props and the headache it caused, I balance them all now.

How do you balance those flimsy props

 

[JamesT1950]

I used the DuBro Tru-spin Prop Balancer for mine. Here is a link

NEW DuBro Tru-Spin Prop Propeller Balancer for Air & Heli - 499 - FREE SHIPPING | eBay

 

[abwRN]

2 P4P’s 2016 & 2017 builds.. Many hours on both and multiple “mishaps”. No cracks.

 

[solentlife]

Yes... when you concentrate on a small number and talk it up and think of nothing else and convince others who join in like on this thread, it seems to be a big problem.
But if you look at actual numbers and the rate of cracking incidents and the proportion of Phantoms that never develop any cracking, it just doesn't stand up.
Is there a factor that might explain the number you've seen among your friends. Did many of them buy from the same source around the same time?

When you don't know the cause of an action or make assumptions that may not be true and take precautions based on invalid assumptions, you are generally wasting your time.
It's the kind of thinking behind sacrificing an animal to ensure a good harvest ... better to be safe than sorry.

It makes a lot more sense to find out how big the problem is and the actual cause of the problem and address that.
The facts are that many of the assumed causes like flight speed, hard turning or braking, poor design, prop balance etc are not valid as is shown by the number of flyers who fly without a care and never see cracking.
The explanation that best fits the evidence is that a small proportion of shells develop cracking because of poor materials and/or moulding technique.

And it's threads like this that add to the false perception and make owners think their Phantom will inevitably develop cracking even though the majority never will.
There are well over a million Phantoms out in the wild. If 10000 developed cracking, that would still be less than 1%.
And if you were unlucky enough to get one of those unlucky shells, DJI replace them under warranty or it's fairly easy and cheap to do it yourself.

1% - you think that's acceptable ? Even if it was true - I don't. We are talking about a machine with four whirling knives at its extreme ends ....

Second - I see no evidence that numbers are few - because obviously many people either do not check their arms ... or do not report on forums ...

If the problem was so small - why are their hundreds of sellers on ebay ... Banggood ... Aliexpress ... Amazon etc. selling plate systems ? There must be a demand to drive people to sell them.

I do not say every P will suffer cracks ... what I say is better to be safe than sorry. Fitting plates will not harm the P and in fact will help alleviate risk of the cracks.

Why do you post as absolute ? Nothing is ... least of all this.

As to the 10 I know of ... all boughty from different sources and different times over a 1 year period. But that means nothing anyway - because who knows how long stock stays on shelf, we do not know batch production numbers etc.

The fact is - it happens, whether its 0.01 or 10% ... does not matter. The person it happens to is not happy. As to DJI replacing shells ... ask the ones who have had shells replaced and then the replacement shell has cracked - what DJI then did ... There are various posts on a number of forums that state DJI refused to replace a second time. Apart from that - says a lot for replacement shells if they crack as well !! Doesn't matter if 1 or 1000 ... its terrible !

The Ford Pinto was recalled in USA for fuel tank reasons. The number of incidents that caused Ford to recall was very few in number in fact. But the fault was there. Does not change the fact that the Pinto could kill occupants.

Nigel

 

[Meta4]

1% - you think that's acceptable ? Even if it was true - I don't.

I didn't suggest it's acceptable or that it's 1% as I don't have actual numbers.
But I do have an idea based on how many report them and how many report none.
And that's what you completely ignore - that the vast majority never develop cracking.
This is a very important factor.
It means that there's nothing wrong with the design, that speed or any of the other guesses are the problem.

If the problem was so small - why are their hundreds of sellers on ebay ... Banggood ... Aliexpress ... Amazon etc. selling plate systems ? There must be a demand to drive people to sell them.

Let me guess ... looking at the number in this thread asking about something to prevent what you've convinced them is almost inevitable ....
Could it be due to people like you giving people a false perception of the prevalence of cracking and convincing that there's a need for "preventative" accessories?

 

[apollo64]

1% - you think that's acceptable ? Even if it was true - I don't. We are talking about a machine with four whirling knives at its extreme ends ....

Second - I see no evidence that numbers are few - because obviously many people either do not check their arms ... or do not report on forums ...

If the problem was so small - why are their hundreds of sellers on ebay ... Banggood ... Aliexpress ... Amazon etc. selling plate systems ? There must be a demand to drive people to sell them.

I do not say every P will suffer cracks ... what I say is better to be safe than sorry. Fitting plates will not harm the P and in fact will help alleviate risk of the cracks.

Why do you post as absolute ? Nothing is ... least of all this.

As to the 10 I know of ... all boughty from different sources and different times over a 1 year period. But that means nothing anyway - because who knows how long stock stays on shelf, we do not know batch production numbers etc.

The fact is - it happens, whether its 0.01 or 10% ... does not matter. The person it happens to is not happy. As to DJI replacing shells ... ask the ones who have had shells replaced and then the replacement shell has cracked - what DJI then did ... There are various posts on a number of forums that state DJI refused to replace a second time. Apart from that - says a lot for replacement shells if they crack as well !! Doesn't matter if 1 or 1000 ... its terrible !

The Ford Pinto was recalled in USA for fuel tank reasons. The number of incidents that caused Ford to recall was very few in number in fact. But the fault was there. Does not change the fact that the Pinto could kill occupants.

Nigel

Well said Nigel, if it was just 1% that cracked there would be next to no demand for lots of companies to sell these plates, i really hope they cure the problem

 

[Meta4]

Well said Nigel, if it was just 1% that cracked there would be next to no demand for lots of companies to sell these plates, i really hope they cure the problem

Since most buyers don't have any cracking but are anxious to prevent it, the number of sales has no relation to the amount of Phantoms that develop cracking.
The fear that this issue generates is way out of proportion with the likelihood or the consequences of it occurring.

 

[solentlife]

Since most buyers don't have any cracking but are anxious to prevent it, the number of sales has no relation to the amount of Phantoms that develop cracking.
The fear that this issue generates is way out of proportion with the likelihood or the consequences of it occurring.

Sorry Meta ... I cannot understand why you are so anti about it ...

Reminds me of the 'Anti seatbelts in cars' people ....

And what is this ... I have convinced people there is a problem ? I've been hearing about cracks in Phantoms ... Nova's .... Zaomi's ..... since early days ... nothing to do with my view on the matter - they were posting about it before I got on the wagon !!

Plus you admit you have no numbers ... so it works both ways ... I cannot prove and you cannot as well ... so why not allow people to decide for themselves.

I will say this and I am not trying to insult : If I was a new owner and your posting convinced me to not fit plates and down the road - I end up with cracks - I would not be very happy.

And I certainly do not believe all those plates are on sale because of scaremongering by people like me ... I use word scaremongering just to cater for your view.

Prevention is better than cure.

Nigel

 

[Meta4]

Sorry Meta ... I cannot understand why you are so anti about it ...

That's obvious.
Maybe it's because I'm a scientist and like to consider the evidence rather than act on fear.

 

[solentlife]

That's obvious.
Maybe it's because I'm a scientist and like to consider the evidence rather than act on fear.

Evidence ? You say yourself you have no numbers .....

I remember a Science Professor I studied under ... the class was working through a Physics problem. I noticed a flaw in his sequence on the board. Class picked it up as well. He insisted his sequence was correct. His final results did not match the experiment.
I politely repeated my query on the calculation sequence and finally the penny dropped ...

As you would be well aware - often in science you have to assume a factor and the factors validity will be confirmed or not in the results. He had assumed a factor of 0.3 for 1/3rd ....

So Scientist or not ... numbers do not lie. And you and I have no numbers to quote. Just perceptions which are definitely not scientific proof .....

I maintain my view that prevention of any possibility of cracks is valid. Whether it happens to 1 in 10,000 or more ... I don't care. I don't want cracks ... and I believe others do not either. You view is just that a point of view with no basis to prove.

Nigel

 

[apollo64]

Sorry Meta ... I cannot understand why you are so anti about it ...

Reminds me of the 'Anti seatbelts in cars' people ....

And what is this ... I have convinced people there is a problem ? I've been hearing about cracks in Phantoms ... Nova's .... Zaomi's ..... since early days ... nothing to do with my view on the matter - they were posting about it before I got on the wagon !!

Plus you admit you have no numbers ... so it works both ways ... I cannot prove and you cannot as well ... so why not allow people to decide for themselves.

I will say this and I am not trying to insult : If I was a new owner and your posting convinced me to not fit plates and down the road - I end up with cracks - I would not be very happy.

And I certainly do not believe all those plates are on sale because of scaremongering by people like me ... I use word scaremongering just to cater for your view.

Prevention is better than cure.

Nigel

I really wish i had paid more to this subject soon after i got my P3, i checked it once in a while and no cracks, life is good, so i though, had i known it was going to happen to my quad i would have fitted the plates before the issue happened, and i really do feel this is a bigger problem than being admitted to, I just hope the plates prevent the problem getting worse, even though i have ordered a new quad from a different maker, i would actually like to keep the P3 for a while longer

 

[solentlife]

My observation is that the plates slow down the cracks formation or increase. They do not 100% prevent.

Nigel

 

[Mark The Droner]

I don't think speed has anything to do with the motor mount cracks. I used to think it was probably over-torque of the motor mount screws. Then I thought it was probably inferior plastic molding. Now I think it's probably the software-induced hard braking of the more modern DJI ACs starting with the P3. I don't have any numbers.