when to change props
- Thread starter haris_g
- Start date
any ideas? maybe if i make more clear my question?
to make it more clear: is there some kind of rule like “ every 100 hours change the props” etc to know beforehand or just wait for a prop to snap and then change it (which does not really sound so appealing as a technique...)
to make it more clear: is there some kind of rule like “ every 100 hours change the props” etc to know beforehand or just wait for a prop to snap and then change it (which does not really sound so appealing as a technique...)
Good question - and I'm surprised nobody else seems interested in it ;-)
Certainly I've never seen manufacturers in this sector quoting relevant figures. In general engineering terms, this is connected with MTBF - Mean Time Between Failures. As an operator, you have to decide the criticality of each component and then choose a scheduled replacement timetable based on a percentage of that MTBF rating. For example, if the manufacturer quotes 10,000 hours MTBF, you might choose to replace the component at 10,000 hours usage (for a non-critical component) or 5,000 hours (for a critical component). Without this MTBF figure being available, you have to guess at what it should/might be and adjust it subsequently if it proves (statistically, based on suffered failures) to be have been optimistic or pessimistic.
If you are operating commercially then you could (should?) log flight hours for your craft and every sub-component. Based on a planned replacement schedule, this would enable you to accurately predict your operational costs, to include capital costs and maintenance costs, thereby arriving at a figure for "cost per flying hour" from which you can decide how much to charge clients.
Certainly I've never seen manufacturers in this sector quoting relevant figures. In general engineering terms, this is connected with MTBF - Mean Time Between Failures. As an operator, you have to decide the criticality of each component and then choose a scheduled replacement timetable based on a percentage of that MTBF rating. For example, if the manufacturer quotes 10,000 hours MTBF, you might choose to replace the component at 10,000 hours usage (for a non-critical component) or 5,000 hours (for a critical component). Without this MTBF figure being available, you have to guess at what it should/might be and adjust it subsequently if it proves (statistically, based on suffered failures) to be have been optimistic or pessimistic.
If you are operating commercially then you could (should?) log flight hours for your craft and every sub-component. Based on a planned replacement schedule, this would enable you to accurately predict your operational costs, to include capital costs and maintenance costs, thereby arriving at a figure for "cost per flying hour" from which you can decide how much to charge clients.
kloner
Aerial DP
I get chips it them from dirt and crap , other than that i fly em till they break. Your not gonna have a failure unless it's damaged. the cheap plastic stuff might, but not the graupners
always check them over before you fly. look at the leading edge. when they get tore up they come out of balance too
always check them over before you fly. look at the leading edge. when they get tore up they come out of balance too
Gotta disagree with you on that one. Most (all?) plastics are affected by UV light, which will make the plastic more brittle. Plastic also exhibits stress deformation, fatigue and crack propagation in a similar way to metals. Plus they can be attacked by many chemicals (whether you apply them directly or they are present in the atmosphere). So even if you've never had a blade strike a propeller will become increasingly likely to fail/break in proportion to its flying hours and its age (since manufacture).
kloner
Aerial DP
I'd find it hard to believe a guy asking this will have props more than a year before they've seen the dirt, but that's just my observation. at least in the hobby side of things
stored inside it'd take 10 years with lets say a hundred hours of flight time a year. were talking about a f450...........
stored inside it'd take 10 years with lets say a hundred hours of flight time a year. were talking about a f450...........
As props are such a product that manufacturer has no way to control how or where (what motor, what load, motor balance problems, pilot) they are used then obviously they cannot give then any kind of MTBF-figure. And as the props are subject to physical abuse, elements, chemicals etc. such a figure is not possible to predict anyway.
This is a tricky subject as you cannot be sure of any prop you buy. The production run might be perfect or it might be a failure. Even single props in a batch might be bad. And as there is no mandatory quality control protocol you cannot trust any prop is good to start with. So, if you start to change props by the hour it is almost a sure thing that sooner or later you will change a perfectly good prop to one that fails prematurely.
IMO the only proper way to go about this is to inspect every prop often enough and if there is visible damage or stress marks on the prop then scrap it, inspect the new one and if its ok install it. Repeat indefenetly.
This is a tricky subject as you cannot be sure of any prop you buy. The production run might be perfect or it might be a failure. Even single props in a batch might be bad. And as there is no mandatory quality control protocol you cannot trust any prop is good to start with. So, if you start to change props by the hour it is almost a sure thing that sooner or later you will change a perfectly good prop to one that fails prematurely.
IMO the only proper way to go about this is to inspect every prop often enough and if there is visible damage or stress marks on the prop then scrap it, inspect the new one and if its ok install it. Repeat indefenetly.
Good point
thank you gentlemen,
dear jes1111 as you right say the MTBF of the prop is what I need to know, but seams there is no known or announced figure, so I assume it's through experience I should get to know that. Does anyone like to share from his personal experience a figure to start with, be it in hours or flight times ?
dear kloner, i don’t mean to be ironic, but when you say " other than that i fly em till they break " and assuming that this doesn’t necessarily happen on the ground , you also mean that you bear the cost of hard landing every time a prop breaks?
dear jes1111 as you right say the MTBF of the prop is what I need to know, but seams there is no known or announced figure, so I assume it's through experience I should get to know that. Does anyone like to share from his personal experience a figure to start with, be it in hours or flight times ?
dear kloner, i don’t mean to be ironic, but when you say " other than that i fly em till they break " and assuming that this doesn’t necessarily happen on the ground , you also mean that you bear the cost of hard landing every time a prop breaks?
Sure, but he asked the question - so he can choose between my reasoned answer or your "fuggit" approach ;-) Either is valid - particularly because of what ToniCH just added.
+1 good one
Hi haris_g,
I have basically the same set up as you Re: DJI F450 w/naza controller and the spektrum DX6i.
Took it out this morning for it's maiden flight after a short flight just a few minutes one of the props broke flipped it upside down and broke the other 3. These were the 10" props.
Put a set of 8" props on it. After less than a minute, it broke a blade on one prop. Was not very high and was able to set it back down.
Don't know what caused them to break, did not hit anything - these are brand new blades that came with my 450.
I don't think I tightened them to tight but this seems to be the only answer.
I have ordered a couple of more sets and will have to wait until next week to try again.
If any one has any ideas of why the blades broke please let me know.
Thanks
Jeff M
I have basically the same set up as you Re: DJI F450 w/naza controller and the spektrum DX6i.
Took it out this morning for it's maiden flight after a short flight just a few minutes one of the props broke flipped it upside down and broke the other 3. These were the 10" props.
Put a set of 8" props on it. After less than a minute, it broke a blade on one prop. Was not very high and was able to set it back down.
Don't know what caused them to break, did not hit anything - these are brand new blades that came with my 450.
I don't think I tightened them to tight but this seems to be the only answer.
I have ordered a couple of more sets and will have to wait until next week to try again.
If any one has any ideas of why the blades broke please let me know.
Thanks
Jeff M
Jeff M, you need to read the forums more to avoid problems. There is numerous threads about the bad DJI props and countless of discussions of decent replacements. So, there is a quality problem with the DJI props they obviously haven't been able to solve and therefore the props are unusable.
dear JeffM434 sorry to hear that but if it makes you feel any better you are not alone in this, as ToniCH is saying there is a thread in this forum discussing this problem of stock DJI props snapping without any reason.
In short it seams that there is a quality issue with some stock props that cause them to snap regardless of how well you mount them or treat them, if I remember well a forum member reported that thread lock might accelerate the snap process.
Bottom line, get your self some other brand of props and you'll soon forget this unpleasant incident
In short it seams that there is a quality issue with some stock props that cause them to snap regardless of how well you mount them or treat them, if I remember well a forum member reported that thread lock might accelerate the snap process.
Bottom line, get your self some other brand of props and you'll soon forget this unpleasant incident
Lol.
My Hexa crashed today after it's second flight with carbon fiber props (Gemfan). One prop snapped mid flight bringing my flat Hexa down. I should have stayed with my APC slow flyer plastic props. They flex under stress vs. complete catastrophic failure. And the crazy part was that I wasn't doing crazy maneuvers with my craft. A simple forward flight and climb resulted in 2+ grand in pieces. Don't buy into the carbon fiber craze. Graupners seem to be the only reliable kid on the block, but I'm going to stay with APC.
My Hexa crashed today after it's second flight with carbon fiber props (Gemfan). One prop snapped mid flight bringing my flat Hexa down. I should have stayed with my APC slow flyer plastic props. They flex under stress vs. complete catastrophic failure. And the crazy part was that I wasn't doing crazy maneuvers with my craft. A simple forward flight and climb resulted in 2+ grand in pieces. Don't buy into the carbon fiber craze. Graupners seem to be the only reliable kid on the block, but I'm going to stay with APC.