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Mavic - Propeller Cage (What for changed the design)
1551 17 2017-8-16
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fansbf038726
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DJI please clarify the situation — You have officially changed the design of prop guards?
Wanted to buy, but in the photo prop guards has a new hole on the perimeter. This is the official version of DJI? Or fake?
Yesterday on the official site were old pictures:
http://store.dji.com/product/mavic-propeller-cage
Was going to write thought counterfeit was changed the design.

$_10.jpg

But since the protection effectiveness is reduced, and the finger can be easily inserted into the opening. Question if I find the old version - it works not worse? Or the changes were constructive, and linked to aerodynamics?
In terms of the algorithm of the firmware, designed for the old version without the holes, and the new version of prop guards with holes?
2017-8-16
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Oracle Miata
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Man, that just looks heavy.
2017-8-16
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Mari
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With holes, less weight.... prop guard is for protection prop during flights... When the Mavic is up in the air you can't stick your finger in one of the holes...
2017-8-16
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fansbf038726
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Mari Posted at 2017-8-16 10:54
With holes, less weight.... prop guard is for protection prop during flights... When the Mavic is up in the air you can't stick your finger in one of the holes...

Well, tree branches, palm leaves...  So I understand, DJI decided to save on plastic.
Well, actually, if I tape the holes with adhesive, then what's the harm? After initially mounting was deaf.


2017-8-16
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BumblerBee
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fansbf038726 Posted at 2017-8-16 21:19
Well, tree branches, palm leaves...  So I understand, DJI decided to save on plastic.
Well, actually, if I tape the holes with adhesive, then what's the harm? After initially mounting was deaf.

Using light-weight transparent Scotch should do the trick, yes. Just make sure to tape over all of the holes to avoid imbalance in the air flow.
2017-8-17
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DroneFlying
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fansbf038726 Posted at 2017-8-16 21:19
Well, tree branches, palm leaves...  So I understand, DJI decided to save on plastic.
Well, actually, if I tape the holes with adhesive, then what's the harm? After initially mounting was deaf.

Maybe I'm overlooking something but I don't see any difference in the various photos you posted other than the fact that on DJI's product page the cage appears to be sitting upside down. Can you clarify what the change is that you suspect occurred and what holes you're talking about covering up?

I do know that I've consistently heard that the Mavic is noticeably louder when using the propeller cage. I'd guess that's probably caused by the motors having to spin faster to create the same amount of lift with smaller propellers, and if that's the case then I doubt there's anything you can do about it. I certainly wouldn't be inclined to try to "improve" the cage (or the noise level associated with it) by covering parts of it with tape or anything else.

2017-8-17
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fansbf038726
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DroneFlying Posted at 2017-8-17 05:19
Maybe I'm overlooking something but I don't see any difference in the various photos you posted other than the fact that on DJI's product page the cage appears to be sitting upside down. Can you clarify what the change is that you suspect occurred and what holes you're talking about covering up?

I do know that I've consistently heard that the Mavic is noticeably louder when using the propeller cage. I'd guess that's probably caused by the motors having to spin faster to create the same amount of lift with smaller propellers, and if that's the case then I doubt there's anything you can do about it. I certainly wouldn't be inclined to try to "improve" the cage (or the noise level associated with it) by covering parts of it with tape or anything else.

Originally the official website was pictures of solid protection. And they were there until the day before yesterday.I thought everyone saw and remember the old version of Propeller Cage...
large_0b991ba0-4e76-4518-9f13-cee9b898d047.jpg large_181e2d2c-0ee8-4d30-b1cd-6e7876893474.jpg large_00730b21-ae69-40eb-a831-af6c193f77f2.jpg large_e59e5efa-3a28-4146-81a0-7af40c4748e8.jpg MAVIC Propeller Cage.jpg

2017-8-17
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fansbf038726
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Can be punched in the holes to make it easier to push the propellers?
2017-8-17
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Mari
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... simple solution... don't fly that close to trees so you don't need the prop cage
2017-8-17
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DroneFlying
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fansbf038726 Posted at 2017-8-17 07:48
Originally the official website was pictures of solid protection. And they were there until the day before yesterday.I thought everyone saw and remember the old version of Propeller Cage...

Ah, now I see what you mean. Yes, it looks like they changed the design, but I doubt very much that putting tape over the holes on the edges will make it quieter.
2017-8-17
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fansbf038726
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DroneFlying Posted at 2017-8-17 09:14
Ah, now I see what you mean. Yes, it looks like they changed the design, but I doubt very much that putting tape over the holes on the edges will make it quieter.

Yes, for me the question is not the volume of noise. And the safety factor - I'm going to fly in the arboretum with Palm trees.
2017-8-18
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Bernoullis
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DroneFlying Posted at 2017-8-17 05:19
Maybe I'm overlooking something but I don't see any difference in the various photos you posted other than the fact that on DJI's product page the cage appears to be sitting upside down. Can you clarify what the change is that you suspect occurred and what holes you're talking about covering up?

I do know that I've consistently heard that the Mavic is noticeably louder when using the propeller cage. I'd guess that's probably caused by the motors having to spin faster to create the same amount of lift with smaller propellers, and if that's the case then I doubt there's anything you can do about it. I certainly wouldn't be inclined to try to "improve" the cage (or the noise level associated with it) by covering parts of it with tape or anything else.

"I do know that I've consistently heard that the Mavic is noticeably louder when using the propeller cage. I'd guess that's probably caused by the motors having to spin faster to create the same amount of lift with smaller propellers ......"

I am willing to bet that a major part of the increased noise is due to airflow interference between the tip of the props and the circular wall of the cage, be it the earlier solid one, or the apparently newer one with holes in it noted in this thread.  Don't forget that the props rotate at very high RPM and generate substantial vortexes on the trailing edge, particularly near the tips.  These high-energy vortexes will interact with anything close to them, like the circular cage wall, thereby generating noise (and drag!).

The 7728 model props used with the prop cage are specifically designed for that accessory.  The standard Mavic props are the 8330 model, which are, I believe, slightly longer and therefore have a more tapered chord toward the tip, which will also help make them a little less noisy than the 7728 model.
2017-8-18
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Drone-Mike
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What's the flight time if these are used? Seems like it'd be reduced a lot.
2017-8-18
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DroneFlying
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Drone-Mike Posted at 2017-8-18 04:32
What's the flight time if these are used? Seems like it'd be reduced a lot.

I've seen a couple of people say that it cuts flight time by around 50%, which sounds about right given the extra weight and smaller propellers.
2017-8-18
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DroneFlying
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Bernoullis Posted at 2017-8-18 04:10
"I do know that I've consistently heard that the Mavic is noticeably louder when using the propeller cage. I'd guess that's probably caused by the motors having to spin faster to create the same amount of lift with smaller propellers ......"

I am willing to bet that a major part of the increased noise is due to airflow interference between the tip of the props and the circular wall of the cage, be it the earlier solid one, or the apparently newer one with holes in it noted in this thread.  Don't forget that the props rotate at very high RPM and generate substantial vortexes on the trailing edge, particularly near the tips.  These high-energy vortexes will interact with anything close to them, like the circular cage wall, thereby generating noise (and drag!).

The biggest factor in noise is going to be the speed (RPM); smaller propellers will have to spin faster to generate the same lift. And in this case they'll have to generate even more lift than the standard propellers because they also have to compensate for the extra weight of the cages.
2017-8-18
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Bernoullis
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I accept that inceased RPM will raise the noise level generated by the props, but I remain to be convinved that it will be the biggest factor.  I feel pretty sure the very close proximity of the fixed/stationary outer ring of the prop guards will be majorly influential in noise production.

The vortexes spilling off the tip and trailing edge of the propellors (the initial noise generated by the props, as it were are) is now impacting a guard ring that has had holes made in it (the new design - to save a few grams of weight?).  That drag must cause the fast moving vortexes to mix very quickly with the surrounding air, generating further rapid pressure waves, thus further noise.

I would be interested to see the results of some clever person doing the mathematics and discovering just how close those props (especially near the tips ...) are to creating trans-sonic pressure waves.
2017-9-18
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DroneFlying
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Bernoullis Posted at 2017-9-18 23:25
I accept that inceased RPM will raise the noise level generated by the props, but I remain to be convinved that it will be the biggest factor.  I feel pretty sure the very close proximity of the fixed/stationary outer ring of the prop guards will be majorly influential in noise production.

The vortexes spilling off the tip and trailing edge of the propellors (the initial noise generated by the props, as it were are) is now impacting a guard ring that has had holes made in it (the new design - to save a few grams of weight?).  That drag must cause the fast moving vortexes to mix very quickly with the surrounding air, generating further rapid pressure waves, thus further noise.

I remain to be convinved that [RPM] will be the biggest factor [in the noise level].

Think what you like, but without or without the propeller cage the Mavic definitely makes more noise when the propellers are spinning faster. Ever noticed how it gets louder when you take off, for example? And as I pointed out earlier, these props have to spin even faster than the normal ones to generate the same amount of lift.

I would be interested to see the results of some clever person doing the mathematics and discovering just how close those props (especially near the tips ...) are to creating trans-sonic pressure waves.

I can't imagine why anyone would bother. The one thing that everyone who has it seems to agree on is that the Mavic is louder with the propeller cage, and mathematics isn't going to change that.
2017-9-19
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Bernoullis
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"I can't imagine why anyone would bother."

And I shan't be bothering with this thread anymore, as differing opinions are obviously not welcome!

2017-9-19
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