Any suggestions how to avoid MM falls?

[Saigondroner]

I have been flying drones for close to a decade, and have a MM also. Based upon the analyses, and conclusions, the main question seems to be "When will it crash?"

Apart from simply grounding it, are there any suggestions how to avoid this outcome....perhaps just to minimize the risk.

Thanks!

 

[sar104]

I don't see anything conclusive yet, but there seem to be strong indications that the problems are related to deformed props, especially on the rear motors. The two resulting behaviors are low forward speed, due to insufficient forward pitch, and uncommanded descent, presumably due to insufficient thrust.

Whether the deformation of the props is due to bending in the folded storage configuration or simply a result of repeated use isn't clear.

 

[Saigondroner]

I don't see anything conclusive yet, but there seem to be strong indications that the problems are related to deformed props, especially on the rear motors. The two resulting behaviors are low forward speed, due to insufficient forward pitch, and uncommanded descent, presumably due to insufficient thrust.

Whether the deformation of the props is due to bending in the folded storage configuration or simply a result of repeated use isn't clear.

Thank you. I do plan on doing a few test flights using the 8 MM blades I thinly coated with 2 part epoxy.

My concern is the prop weakness will crack the epoxy & ablate away, making things worse.

Test plan is:

All stock, 4F, 4R.
All JB’ed 4F, 4R
4F stock, 4R JB’ed.

Flight pattern TBD, based on conditions.

 

[Prismatic]

It seems also that flying backwards can mitigate the problem and allow the pilot to bring the drone back that way.

 

[sar104]

Thank you. I do plan on doing a few test flights using the 8 MM blades I thinly coated with 2 part epoxy.

My concern is the prop weakness will crack the epoxy & ablate away, making things worse.

Test plan is:

All stock, 4F, 4R.
All JB’ed 4F, 4R
4F stock, 4R JB’ed.

Flight pattern TBD, based on conditions.

I'd be concerned about adding weight and MOI to the props - that may end up causing as many problems as it fixes.

 

[sar104]

It seems also that flying backwards can mitigate the problem and allow the pilot to bring the drone back that way.

That may fix the low pitch issue, but it doesn't look like it will fix the uncommanded descent, which is arguably the more serious problem.

 

[Saigondroner]

I'd be concerned about adding weight and MOI to the props - that may end up causing as many problems as it fixes.

All 8 blades weigh 1.4g more than the stock units, in total....175mg / blade. Not too much, but it exceeds the limits.

 

[Saigondroner]

I'd be concerned about adding weight and MOI to the props - that may end up causing as many problems as it fixes.

I guess we were both right :-(. My guess is the prop flex released the expoxy, that peeled off the props like a banana peel.

MOI would have been h*** in any breeze.


I flew indoors, with rear props on the back 1st. I did a CSC quickly,

 

[Prismatic]

I guess we were both right :-(. My guess is the prop flex released the expoxy, that peeled off the props like a banana peel.

MOI would have been h*** in any breeze.


I flew indoors, with rear props on the back 1st. I did a CSC quickly,

Were they destroyed in a crash? Was the drone misbehaving worse with the modified props? (And what's MOI? It's not coming to me.)

 

[sar104]

Were they destroyed in a crash? Was the drone misbehaving worse with the modified props? (And what's MOI? It's not coming to me.)

MOI is moment of inertia.

 

[Saigondroner]

Were they destroyed in a crash? Was the drone misbehaving worse with the modified props? (And what's MOI? It's not coming to me.)

Not at all...it’s like it never happened. Sar104’s thoughts made me revisit my testing plan.

The epoxy did NOT add much rigidity, and started to detach from the props quickly. I hit the CSC switch quickly.

The heavy lift ACs I am familiar with have laminate CF props, with balsawood cores.

These are the MM props, after a peel and wax