Prop Strike in Sport Mode

[LivinLarge]

bird was factory new so my investigation concludes that repeated operation under sport mode conditions will introduce stress at the rear rear prop arm guards or butterflies. Said stress will eventually cause the butterfly to fail and crack and compromise structural integrity. Once cracked the rear prop arms are now allowed to flex farther and during a full descent at full yaw, in either direction, prop arms will flex up and props will strike upper shell.

take your bird and attempt to fold rear prop arms up into body. if you're butterflies ate intact , you shouldn't be able to complete the exercise.

if you're butterflies are damaged, your arms will flex upward and props will scrape upper shell.

make sense?

Maybe this thread will shed some light on the DJI limitation and 1. DJI will own up and remedy affected birds
2. they will reinforce MP2 butterflies

This is a design defect. If the bird is in warranty, they should replace it.

 

[NastyNate]

This is a design defect. If the bird is in warranty, they should replace it.

1st call = this is normal under sport mode operation

2nd call = DJI offers to RMA bird.

I did consider this. After taking into consideration, the turn around time and other pilots horrible experiences with the lack of DJI service, lost parts and different SNs being shipped back, I've elected to do my own repairs. Then I read the class action thread in this forum and that was the nail in the coffin.

 

[naturecannon]

This is a design defect. If the bird is in warranty, they should replace it.

I agree

 

[lannes]

I thought so too. my first course of action was to contact DJI who then advised this is normal when in Sport mode.

I'd raise it at the DJI Mavic forum as well, see what the official DJI moderators say and then use this and their comments as evidence with DJI support to get a replacement.

In all my time on these forums, I've actually not seen a similar issue, if this had been a "design limitation" a lot more people would have been raising this.

When you google it and search in google images, your the only reference for a rear prop strike coming up, so it is not a "normal" occurrence as DJI support claims it is. There is actually no rear prop strike on any drone that a google search brings up.

DJI need to replace this AC, it's a manufacturing fault, it's that simple.

I'd raise it as a public safety issue with them if the AC comes down during a flight and injures someone they would be liable for a faulty design, if they say it's a design limitation then that is still a problem for them because they should not be providing sport mode as a flight option as it can cause the AC to come down.

 

[Bazzam]

bird was factory new so my investigation concludes that repeated operation under sport mode conditions will introduce stress at the rear rear prop arm guards or butterflies. Said stress will eventually cause the butterfly to fail and crack and compromise structural integrity. Once cracked the rear prop arms are now allowed to flex farther and during a full descent at full yaw, in either direction, prop arms will flex up and props will strike upper shell.

take your bird and attempt to fold rear prop arms up into body. if you're butterflies ate intact , you shouldn't be able to complete the exercise.

if you're butterflies are damaged, your arms will flex upward and props will scrape upper shell.

make sense?

Maybe this thread will shed some light on the DJI limitation and 1. DJI will own up and remedy affected birds
2. they will reinforce MP2 butterflies

I fly a fully modded mavic - super sport + etc, top speed 85km
For over 6 months - 500km + and it has not resulted in any observable damage to date, I think you got a lemon to be honest...
Normal sports mode shouldn't result in that type of damage

 

[KostasNK]

Why would someone descend fully and yaw fully at the same time? Is there something usefull to be achieved by this manoeuvre?

 

[Mike4884]

It doesnt matter kostasnk how he fly's it shouldnt happen

 

[KostasNK]

It doesnt matter kostasnk how he fly's it shouldnt happen

I agree with you, but I would like to know what is the use of this manoeuvre...
Just to show of as an aerobatic manoeuvre?

 

[Dragonfly]

Thank you, perfect.

There is no need to remove the bottom plate/shell to replace / repair any of the 4 legs. Just the top shell.

 

[Dragonfly]

I'd raise it at the DJI Mavic forum as well, see what the official DJI moderators say and then use this and their comments as evidence with DJI support to get a replacement.

In all my time on these forums, I've actually not seen a similar issue, if this had been a "design limitation" a lot more people would have been raising this.

When you google it and search in google images, your the only reference for a rear prop strike coming up, so it is not a "normal" occurrence as DJI support claims it is. There is actually no rear prop strike on any drone that a google search brings up.

DJI need to replace this AC, it's a manufacturing fault, it's that simple.

I'd raise it as a public safety issue with them if the AC comes down during a flight and injures someone they would be liable for a faulty design, if they say it's a design limitation then that is still a problem for them because they should not be providing sport mode as a flight option as it can cause the AC to come down.

There has been 3 other cases that im aware of that have had prop strike do to this very problem.
Also the back leg mechanism is on a 180° rotation spring loaded hold system, there is no actual lock to lock the arm in place, only spring pressure. It relies on the spring pressure and the flat of the arm resting flush against the butterfly as its stop position when extended.
If from a crash or excessive pressure is applied to the arm and it is forced up and the butterfly is broken then only the spring pressure remains to stop the arm from again going past the extended notch to a straight up position.
Under extreme flight the weight and up thrust on prop and leg and G force will push leg against spring notch allowing props to hit boddy of Mavic.

The front arms have a definite lock within the spring mechanism.

Pic shows the spring. Mechanism that fits inside the back arm and buttefly yoke fits over top of arm joint.

 

[NastyNate]

Got my bird patched up. Shout out to Dragonfly, Thunder Drones and Lolo for the help.

installed 2 new legs and accompanying butterflies.

total time 1 hr.

 

[Simmo]

Well done bud, and that top rear cover looks a whole lot better than the dremelled one!!!!

 

[kakao]

"I've called DJI - who insists this is normal and classifies the above condition as a "design limitation."

This is an absolute disgrace on DJI's side.

Looks like the are begging for someone to sue them should this issue cause damage to people or their property.

.

 

[joejaxvic123]

This scares the hell out of me.

 

[Mike4884]

Nice nastynate good job.... so question do those butterfly pieces just sit in the grooves or are they actually built into the bottom part of the body what makes them come apart?

 

[NastyNate]

Nice nastynate good job.... so question do those butterfly pieces just sit in the grooves or are they actually built into the bottom part of the body what makes them come apart?

they are the yoke of the rear leg assembly. they are not attached to lower shell.

 

[Mike4884]

they are the yoke of the rear leg assembly. they are not attached to lower shell.

So what they just sit there tucked in between the leg and top shell?

 

[NastyNate]

Heavy rains grounding us today. Threw on these decals though. This bird has always reminded me somewhat of an Osprey so I gave her the appropriate markings.

 

[NastyNate]

So what they just sit there tucked in between the leg and top shell?

no. they are attached to the rear leg assembly. Kind of capped on so to speak. these are them broken off, orientated in the position they would be if they were attached.

 

[SouthernComfort]

I’m glad to see you have your bird back in service! Great read in this thread!