Threshold of prop damage?

[BiggityBates]

Hi guys, I have a question about props. I just had my Solo flip on takeoff for the first time. I know my props were on right as I have flown my Solo many times, and I flew it once earlier in the day before the accident. Not sure what caused it, but I also had been using MA props.

Do props HAVE to be in perfect condition to be used, or if they are a bit scraped (not too bad) on one side, does that render them ineffective/likely to cause a problem? When I flip happened, one prop was a total loss. One prop just has a small chip missing from the end. I took scissors and cut it at the proper angle so its a smooth cut instead of a knick., and the other two just got scraped up on the air facing side. Is there a method to salvage props that are just scraped on the edge a bit? Can you use like super fine grain sandpaper and smoothen things out again, or are they a "100% or 0%" type deal. Anyone know? Also, is it black and white? Or is it the kind of situation where if you are using props that have been scraped but smoothed back out that they are usable, but not as efficient? Just curious because 3 of the 4 props aren't badly damaged, but I know aerodynamics are key, especially at the high rps of multicopter blades.... Is there any info out there about such things? I would hate to throw away 3 barely damaged MA props, but if they have to be in perfect condition to not cause problems, then I guess I will go back to stock props.

Thanks for any assistance

 

[msantimanzano]

scrapes etc will not cause a drone to flip. They will however at some point, with enough of a scrape and missing material, start to cause vibrations in the drone and less than perfect response. Remember that if you sand away at a prop, as you remove material you will eventually reach a point where the weight distribution of that prop is different from one side to the other. Thats when you will start having vibration issues.

 

[BiggityBates]

scrapes etc will not cause a drone to flip. They will however at some point, with enough of a scrape and missing material, start to cause vibrations in the drone and less than perfect response. Remember that if you sand away at a prop, as you remove material you will eventually reach a point where the weight distribution of that prop is different from one side to the other. Thats when you will start having vibration issues.

Good point about the removal of material and weight distribution. I didn't think of that. I think that will be the number one problem. I guess not knowing the extent of the scrapes, it would be hard for anyone to say for sure what kind of situation I am looking at.... I don't know if I want to risk it, but I don't really know if I would be throwing away 3 perfectly capable props because of how little damage they have, nor do I know whether or not it would be better to leave the scrapes as is or try to smooth them out somehow, maybe with something even finer than sandpaper, just so there isn't a bunch of tiny, uneven knicks spinning into the wind.

 

[msantimanzano]

I think if you balance them you will be ok

 

[BiggityBates]

Would you recommend leaving the knicks or trying to smooth them out with the finest thing I can?

 

[msantimanzano]

I'd gently smooth them to reduce vibration

 

[Airpower]

Remember that the tip is also the fastest moving part of the propeller and therefore most sensitive to creating lift. Sanding them is fine as long as your balance is good. It's just with a rig like solo that barely flies for 15 minutes and where everything runs hot and wieghs 1700 grams--- I just think everything needs to be absolutely optimal in perfect working condition. Worn props are fine on my smaller fpv birds but with this big a quad that is so well tuned to its power system I would replace any prop that didnt have flawless tips or had ever struck the ground.

 

[Greg Parker]

Why chance it for the cost of a couple of props?

 

[Chuck]

Hi guys, I have a question about props. I just had my Solo flip on takeoff for the first time. I know my props were on right as I have flown my Solo many times, and I flew it once earlier in the day before the accident. Not sure what caused it, but I also had been using MA props.

Do props HAVE to be in perfect condition to be used, or if they are a bit scraped (not too bad) on one side, does that render them ineffective/likely to cause a problem? When I flip happened, one prop was a total loss. One prop just has a small chip missing from the end. I took scissors and cut it at the proper angle so its a smooth cut instead of a knick., and the other two just got scraped up on the air facing side. Is there a method to salvage props that are just scraped on the edge a bit? Can you use like super fine grain sandpaper and smoothen things out again, or are they a "100% or 0%" type deal. Anyone know? Also, is it black and white? Or is it the kind of situation where if you are using props that have been scraped but smoothed back out that they are usable, but not as efficient? Just curious because 3 of the 4 props aren't badly damaged, but I know aerodynamics are key, especially at the high rps of multicopter blades.... Is there any info out there about such things? I would hate to throw away 3 barely damaged MA props, but if they have to be in perfect condition to not cause problems, then I guess I will go back to stock props.

Thanks for any assistance

Remember that MA props are specific to the motors, and you can get them mixed up and put them on the wrong hubs. The stock Solo props only go on one way, so they are easy to tell which one goes where. On the MA props, if you look at the prop dimensions printed on each prop, 2 of the props have an "R" at the end of the printed dimension. Those go with the black hubs. The props with no "R" printed on them go with the silver hubs. I don't know if having the wrong props on the hubs contributed to your flip, but common sense says it is possible. With props available for Solo out there, I would take no chances on chipped or cracked props. Get some spares. One less thing to worry about. Good luck to you, and fly safe.

 

[Joe Horn]

Only use damaged props if you value the feeling of suspense more than you value your Solo.

 

[Pedals2Paddles]

If there are chunks and chips missing off the leading edge or tips, the prop should be put in the trash. No amount of trimming or sanding will correct what is the most important part of a propeller. Any "fix" will be just as degrading as the flaw. And if it hit hard enough to do that, then it hit hard enough to compromise the hub. It could break in flight at any time.

If the top surface just has some superficial marks, not gouged up, just clean it and make sure it's still smooth. If the top surface is significantly scraped up or gouged where it is no longer smooth, trash can. You won't have a nice laminer flow of air over a gouged up surface. And you'll be chasing balance until there's nothing left. Flying with a scraped up top surface will just cause vibration and uneven thrust.

Props are cheap. Buy more.

 

[msantimanzano]

Proud to say that since I got my SOLO in December of 16, I am still flying with my original props. I bought 26 boxes of SOLO props when they were on sale at BB and happy that I have not needed any of them. At some point, Ill sell some off since it doesn't look like I will be needed such an exaggeration of props. lol

 

[Barramundi]

Proud to say that since I got my SOLO in December of 16, I am still flying with my original props. I bought 26 boxes of SOLO props when they were on sale at BB and happy that I have not needed any of them. At some point, Ill sell some off since it doesn't look like I will be needed such an exaggeration of props. lol

You mean you have a spare for the spare, for the spare, for the spare, for the spare, for the spare... Now that's being confident in your flying ability! [emoji15][emoji12]

 

[Barramundi]

Hi guys, I have a question about props. I just had my Solo flip on takeoff for the first time. I know my props were on right as I have flown my Solo many times, and I flew it once earlier in the day before the accident. Not sure what caused it, but I also had been using MA props.

Do props HAVE to be in perfect condition to be used, or if they are a bit scraped (not too bad) on one side, does that render them ineffective/likely to cause a problem? When I flip happened, one prop was a total loss. One prop just has a small chip missing from the end. I took scissors and cut it at the proper angle so its a smooth cut instead of a knick., and the other two just got scraped up on the air facing side. Is there a method to salvage props that are just scraped on the edge a bit? Can you use like super fine grain sandpaper and smoothen things out again, or are they a "100% or 0%" type deal. Anyone know? Also, is it black and white? Or is it the kind of situation where if you are using props that have been scraped but smoothed back out that they are usable, but not as efficient? Just curious because 3 of the 4 props aren't badly damaged, but I know aerodynamics are key, especially at the high rps of multicopter blades.... Is there any info out there about such things? I would hate to throw away 3 barely damaged MA props, but if they have to be in perfect condition to not cause problems, then I guess I will go back to stock props.

Thanks for any assistance

In regards of the flip over, when getting close to the ground (approx under 1m) "ground effect" can occur, which can cause the Solo to flip unexpectedly. GE is the turbulence caused from the downward forced air (from the props of your Solo) bouncing off the ground and being pushed upwards, thus causing the downward and upward air to collide. Best way to minimise a flip is when you get to approx 1m in height when landing is to throttle down and land immediately instead of hovering at that height...my thoughts.

 

[Pedals2Paddles]

In regards of the flip over, when getting close to the ground (approx under 1m) "ground effect" can occur, which can cause the Solo to flip unexpectedly. GE is the turbulence caused from the downward forced air (from the props of your Solo) bouncing off the ground and being pushed upwards, thus causing the downward and upward air to collide. Best way to minimise a flip is when you get to approx 1m in height when landing is to throttle down and land immediately instead of hovering at that height...my thoughts.

What you're describing isn't actually ground effect. It is something that can happen, but is actually very minimal when it comes to an aircraft like the solo out in the open. That can be a problem indoors for sure.

Ground effect as it relates to a multiroter is air pressure increasing under the aircraft from the propeller down wash. That pressure increase enters the solo's body and is picked up the barometric altimeters. The baros see that pressure increase as a descent. The same can happen taking off. It will think it's descending, or at least not climbing, increases power too much, comes out of ground effect, and suddenly reduces power and sinks a bit.

The solo has ground effect compensation to mitigate this in most cases. It prioritizes the accelerators over the barometers when landing and taking off. But, accelerators can be fooled too. If you flying rough, or hit the ground hard, this can fool them both. See this thread for detail: Recognizing, avoiding, and responding to botched landings

 

[BiggityBates]

Thanks guys, I know props are cheap, but I am a cheapskate and would hate to throw away props if there is a minor repair I can do to fix them. But since P2P was kind enough to chime in, I honor his advice very highly, so I will likely just keep them in the drawer and order another set. Thanks all for your input, I appreciate it.

 

[amosea]

An interesting fact that some of you might already know that I learnt in my former career flying helicopters is that although lift does indeed increase with a respective increase in rotational velocity, as stated above, most helicopter blade manufacturers minimize this "asymmetry of lift" by incorporating a design tweak such as a taper or twist along the blade to increase the efficiency along the driven area (middle). Not totally sure if this is done on the Solo blades by either 3DR or MA but maybe something to take into consideration when attempting a repair job on any scuffed/damaged blades, especially if they get more $$$ to buy as their rarity increases. Wonder what cello tape would do to help with laminar air flow? Of course you'd have to do it to both left and right sides of the prop to get that balance, right?

Regarding the flip-overs, I just hand catch my bird most times, from about 5 feet, to avoid any possible mishaps; you just never know with these things. I gingerly grab it by the one leg and as it powers down I let it GENTLY swing down. I've gotten pretty graceful at it now, looks like a funny professional dance move when I do it right

 

[speatuk]

Until you miss and lose a finger. Lol

My gonads are too small to do that lol