How damaged is a blade before it’s garbage?

[Jetdriver100]

I take my props off at the end of each day of flying. I store with them off. Others don’t. I started doing this after I had a motor jammed by one of the prop clips which had broken off.

When you store the Mavic with the prop's off. Do you put anything over the motors? I thought of storing at first with the prop's off when I got it. especially for travel. But, in my hard case the motor shaft would be digging into the semi hard foam material of the case. So, I thought it would be better leaving the prop's on. Maybe I will build some sturdy rubber engine covers

 

[Thomas B]

When you store the Mavic with the prop's off. Do you put anything over the motors? I thought of storing at first with the prop's off when I got it. especially for travel. But, in my hard case the motor shaft would be digging into the semi hard foam material of the case. So, I thought it would be better leaving the prop's on. Maybe I will build some sturdy rubber engine covers

No. However, I do wrap the drone in a hand towel.

 

[Jetdriver100]

No. However, I do wrap the drone in a hand towel.

Hmm. I'm glad you mentioned the clip's. I alway's would carefully inspect the blades. I didn't think to check those. Figured everything else would last forever. Another new routine

 

[RonRob61]

That one is a goner for sure, anything nicked, or any sign of cracking, even if not gone through, flex them before flight and look carefully for this.

Generally, if you ask yourself the question (is this ok ?) then it's best to just replace.
Better for peace of mind rather than flying and always questioning in your mind if it's going to break this flight.

I always cringe a bit watching those YouTube tests, where they damage a prop really badly on a stick etc, or deliberately cut to heck one or two props, then fly.
It looks impressive, but gives people the idea it's possible or ok in some cases.

edit typo

You beat me to it, THIS:
Generally, if you ask yourself the question (is this ok ?) then it's best to just replace.
Better for peace of mind rather than flying and always questioning in your mind if it's going to break this flight.

Could not agree more!!

 

[RustyBonz]

I fly the MPP.

I keep a set of sightly damaged ones(some tip damage or missing tips) for low flying (no more than 30 feet off the ground) around trees and bushes on construction sites and homes and practicing maneuvers, a new set does not last long around tress anyway.

Any high flying or long flights get a fresh set and do a per-flight run up and maneuver test. A new set for $25 seams cheep if you have to hike and search for a couple of hours to find your downed Quad.

Funny story, The only crash I have ever had was right after I replaced some slightly damaged props with OEM DJI props. One prop exploded during my per-flight run up and maneuver test 10 feet off the ground. Crashed hard on the pavement and broke one rear arms off.

I hear you. I do quite a bit of low flying in and around trees in my yard. The advice I got from this forum caused me to think “when in doubt, throw it out” so I went to order 3 complete change out sets (2-pair per, 6 pair) so I compared amazon with B&H. Amazon was slightly higher so Ibought 6 pair from B&H who promptly back ordered them. Later when I was on Amazon I found 6 pairs of props in my cart, I bought them(again) so now I guess I’ll have 12 pair. Oh BTW putting wounded wings on flying thru trees is like getting an old water ball out of your bag before a par 3 over water. Mixed emotions?

 

[RustyBonz]

Agree with the comments posted. That prop is gone:- no question.
In the early period after I bought my M2P (2018), I changed all props after 10 hours logged flying time. Now I am more comfortable with a 20 hour cycle.
Each set (2 pair) that has been replaced is kept as emergency spares for the next 20 hours. If for some reason I had to reuse those props, my plan would be to swap all props.
Nowadays, I have both an M2P and M2Z and do not mix props between either.
All a bit OTT? Maybe.
Quads do not fly very well at all on 3 good props and one unbalanced prop! So, comparing the cost for 2 pair of props every twenty hours of flying, against the cost of replacing a crashed airframe because of some sort of misguided economic gain; to me is an absolute no-brainer.

Happy and safe flying ?

Had one questionable, tiny nick, rotor blade, the sun was setting and it happened that the light angle on a low inspection hover spin and inspect one at a time showed inconsistent performance in what should of been perfect symmetry. So I knew it had to go.

 

[twoheadlines]

Thought about this a bit more after my previous post. A bit of physics has become a larger part of my thinking here.
I can appreciate we are not talking about an F35 here, but some of the same principles still apply, and I doubt most UAV quads have any sort of built in redundancy to take equivalent damage that may be incorporated into an F35.

Any sort of "nick" from a prop' blade will upset the weight and therefore balance of that prop in flight. Even a small nick can and will set up an oscillation, however so slight, when the prop is rotating at the sort of speeds required, particularly at hover. The effect of the oscillation is likely to transfer into the electric motor, which I'm picking has no built in damping mechanisms capable of absorbing extraneous vibration. Even if there is only a "small" nick out of one blade, the damage to the electric motor will be inevitable, though it may take time to manifest itself.
So, I go back to my original post in which I suggested it was something of a no brainer about comparing the cost of replacing props, on a regular and early cycle, against the cost of a complete UAV airframe. A damaged, unbalanced, prop' will sooner or later become a damaged electric motor which, under Murphy's law, is more than likely going to lead to a catastrophic failure at a point in flight where maximal damage (read: total loss) is most likely!

NOTE:

Don't forget, a damaged prop' can only be rotated between two electric motors. Damage to both motors does not equate to a mitigation of potential failure, even if failure might not happen at the same time. I suspect the knock on effect could include, loss of performance plus an increase power consumption - maybe even battery failure.
Again, physics comes into play in a big way; from what might be seen as a small nick in the blade of one prop'!

Happy and safe flying ? ?

 

[Frustrated]

Junk

 

[Vigylance]

You should see what I flew on for years. Props are tough as nails, you do lose performance though.

 

[Joe4flight]

I see this is a popular topic and agree it should be. Many of us have had minor crashes with damage to only one or more props. Since I’ve been flying, I’ve kept a baggie with damaged propellers to use just in case I run out of props. I labeled the baggie, “slightly damaged”. After reading this thread, I tossed all 6 of them in the garbage. They all had minor cracks or missing chucks. Thanks for posting this important topic.

Here’s a pic of a recent blade I replaced. Snagged on a tree branch. I usually replace right away at any sign even a scratch. Was wondering if this (picture) is truly garbage or I’m being over carful?

 

[GregS]

Here’s a pic of a recent blade I replaced. Snagged on a tree branch. I usually replace right away at any sign even a scratch. Was wondering if this (picture) is truly garbage or I’m being over carful?

That kind of damage will eventually bring you bird down...extremely fast too. Most likely sooner than later. Replace it and save you drone.

 

[John S]

My rule of thumb for a prop of any kind (ie drone, helicopter or fixed wing) is if it touches anything other than air, it get tossed in the trash.

 

[Baqca Sanke]

well everyone here basically said it...
but i'll add that with my spark an the quick release props, the catastrophic damage on blades would always occur NOT where the blade hit the object (the ground or tree or what not) but where the blade base attached to the motors. This area actually sees the greatest amount of forces when a blade stops spinning due to hitting something. This is because that little plastic tab that holds the base of the props to the motor experiences a high rotational torque force when it goes from 400+ rpm to 0 in an instant.

You can inspect the props and notice a small nick on the leading edge and not realize that the little tabs that hold it onto the motors actually experienced more force and damage. Thus on your next flight or two this tab breaks under normal flying conditions and your drone falls from the sky.

As such i deem any props involved in a crash as suspect to intense inspection, and any prop with noticeable damage in any way gets tossed.

 

[ChipDjipro]

Why would anybody want to keep a damaged prop when they cost so little versus the cost of a drone. ?‍

 

[assamfishhead]

Changing the props (when they appear to be damaged) is cheaper than changing the drone.
I use the MasterAirscrew ones - no problems and I believe they are slightly quieter...or just maybe I prefer the sound they make compared to the stock ones.

 

[Amorotor]

I don't know about drone blades but I can tell you that helicopter blades can take a lot of damage and still work! We chopped down tree limbs going into landing sites and took a lot of bullet holes. We could get some frame vibration from irregular lift coming off damaged blades and the sounds the blades would make with air compressing through bullet holes could be terrifying but the blades still worked. We solved the noisy blade problem by taping over the holes with "100 mph" duct tape and hammered the blunted edges back into shape. Cracks are a problem in that blade vibration causes stresses which lengthens the crack leading to metal failure. We would drill a small hole at the end of the crack to stop it propagating. We went through a lot of blades so extending the life of ones that could still work despite being damaged was a common practice. Drone blades aren't made out of metal though so you can't use them to chop down tree limbs nor will they withstand a bullet hole. That said, if there is a small crack in the leading edge, you can carefully, with a round file, reshape the crack so it forms a small cup shape instead of a V shape that propagates vibration cracking leading to blade failure. I bet the plastic blades will take a lot more stress than people are estimating if you eliminate the stress points.

 

[MAvic_South_Oz]

Sounds like you've had some interesting times aloft in the helis

I bet the plastic blades will take a lot more stress than people are estimating if you eliminate the stress points.

Oh they will, youtube videos for prop test are really interesting.
It's more a matter of how safe and how much risk (albeit minor) and good / bad luck with losing a fairly costly drone.

Comparing it to your past heli flights though, those sort of put drone prop risk into perspective a bit though

 

[twoheadlines]

Hah! I can kind of visualise the effect of a 60cal on a quad. If you could find a piece of blade worth reshaping, the next problem might be to find a piece of the airframe worth attaching it too. ?
I'm struggling to write this as I laugh at the mental picture I am seeing.

As already pointed out: the post puts a "slightly" different perspective on the concepts of risk around damaged UAV prop' blades. Very similar physics apply nevertheless; unbalanced blades, vibration, fatigue, failure.

Happy and safe flying ??

????

 

[drakkor]

Here’s a pic of a recent blade I replaced. Snagged on a tree branch. I usually replace right away at any sign even a scratch. Was wondering if this (picture) is truly garbage or I’m being over carful?

I also replace my props right away at any sign even a scratch. Better spend an extra $30 than the full drone price.

 

[Drgnfli]

Fly fearlessly. See my field repairs.

It must be nice to be "rich" and to be able to afford a new drone when ever the props completely fail... When in doubt, change them out!...