Avoid non-DJI 1345S Quick Release Prop Mounts

[skylabimaging]

BTW the reason the CNC alloy hubs would be quieter is all down to flex and balance. As the OEM plastic hub flexes (even 0.5mm) the prop is then off balance with the motor bell housing, and you will get vibration and other strange noises. I agree, the CNC alloy hubs are way quieter and smoother - and better for reducing visual vibration because flex is minimised and the prop stays in true alignment with the bellhousing.

One thing to point out, I know there are some "cast" alloy hubs floating around on the interwebs. Use only CNC hubs. There are so many issues with rotating cast parts, as well as they can be extremely brittle and have internal flaws during the casting, making them even worse than the DJI OEM hubs...

Tolerance...as an engineer, I would assume you understand this and the purpose that it serves.

Anyone had any luck finding a suitable torque wrench (that doesn't cost $1,000 USD)?

So it seems reasonable to conclude that any failures are likely due to over tightening of the hub?

I'm starting to think the folks that were hoarding screw on props are looking like geniuses.

Plenty...go visit your local hardware store...if you need an r/c related one, visit your local hobby shop, ask them if they have one or what their tech uses

I tend to agree with your comments about pilots panicking and over-reacting.
These hubs and springs are very cheap to buy, so if you are worried about them why not just routinely replace them.
At least your DJI warranty will then be protected!

As you should, you are told by DJI to replace them after 200 flights, its a wear and tear item.

 

[Ward Paterson]

Tolerance...as an engineer, I would assume you understand this and the purpose that it serves..

Tolerance for a part like this should be +/- 0.05mm not 0.5mm. As a simple human, I hope you understand the difference.

 

[skylabimaging]

Tolerance for a part like this should be +/- 0.05mm not 0.5mm. As a simple human, I hope you understand the difference.

I do. I also understand it from and engineering standpoint. I also understand multirotors. Maybe you should retire early and design your own since you clearly know better than anybody here

 

[Ward Paterson]

I do. I also understand it from and engineering standpoint. I also understand multirotors. Maybe you should retire early and design your own since you clearly know better than anybody here

I actually do design my own full carbon frame drones from the ground up Maybe you should try it some time. Its an interesting process of prototyping and test flying, and you quickly work out what works and what doesn't.

The forum is for opinions, whether you take mine on board is up to you - no need to blow your shiz over it. I'm glad you've not had any DJI OEM hub failures. Keep using them, its your choice. I've also had plenty of flights on the plastic hubs without an issue, but I refuse to use them now as I've also seen a lot of "close failures" in the repairs I've done for others.

 

[Ward Paterson]

Prop wear with CNC T6061 alloy hubs after 100 repetitive installs/removals + approx. 20 flights. Installation and removal of the prop is as per the DJI instructions..

Prop lugs looks no different to any of the others that have not gone through the 100 install/removals..

 

[Aviator]

As you should, you are told by DJI to replace them after 200 flights, its a wear and tear item.

No, the maintenance manual does not say replace them after 200 flights, it says to Inspect them after 200 flights, this is what it says about the props
1. Check the propellers. If there is any bending,
breakage or cracking on a propeller, do not use it.
2. Attach the propeller to the motor, turn on the aircraft,
and place it on the ground. Stand 1 meter away from
the aircraft and observe the rotating propellers. If you
can see two distinct propeller outline layers, when
looking at a spinning propeller from the side, this
propeller is damaged and should not be used.

 

[skylabimaging]

I actually do design my own full carbon frame drones from the ground up Maybe you should try it some time. Its an interesting process of prototyping and test flying, and you quickly work out what works and what doesn't.

The forum is for opinions, whether you take mine on board is up to you - no need to blow your shiz over it. I'm glad you've not had any DJI OEM hub failures. Keep using them, its your choice. I've also had plenty of flights on the plastic hubs without an issue, but I refuse to use them now as I've also seen a lot of "close failures" in the repairs I've done for others.

After I said that, I knew you were gonna say you did. :footinmouth:

No, the maintenance manual does not say replace them after 200 flights, it says to Inspect them after 200 flights, this is what it says about the props
1. Check the propellers. If there is any bending,
breakage or cracking on a propeller, do not use it.
2. Attach the propeller to the motor, turn on the aircraft,
and place it on the ground. Stand 1 meter away from
the aircraft and observe the rotating propellers. If you
can see two distinct propeller outline layers, when
looking at a spinning propeller from the side, this
propeller is damaged and should not be used.

You're right..Shoulda been more specific in the terminiology. It's in page 2 of the 1345s Quick Release Propeller Quick Start Guide

either way.

No. 5 -
The propellers, securing springs, and mounting
plates have an approximate lifespan of 200
flights. Inspect them regularly to determine if they
should be replaced sooner.

 

[Aviator]

After I said that, I knew you were gonna say you did. :footinmouth:




You're right..Shoulda been more specific in the terminiology. It's in page 2 of the 1345s Quick Release Propeller Quick Start Guide

either way.

No. 5 -
The propellers, securing springs, and mounting
plates have an approximate lifespan of 200
flights. Inspect them regularly to determine if they
should be replaced sooner.

Yup.
I agree with you, we should regularly inspect them and replace when signs of wear are evident.
They are after all very cheap to buy and easy to fit, the studs that hold them down are not threaded all the way down so it should be easy to tighten them without splitting the plastic hubs (all things being equal)

 

[Ward Paterson]

This hub was on an Inspire 1 that had done 50 flights. To me this is not air worthy. However the props looked like new even though they were the only set he'd used for the 50 flights.

The owner did not know much about maintenance either, and 2 of the 4 hubs had loose screws as well...

 

[The Editor]

OK, here's my take on the whole situation (again).
Personally I have never liked the QR prop system and have never used it. The 'Free Props and hubs' went straight to landfill.

Redundancy is good in the aviation world and if its possible to have multiple redundancy then better still.
What is this insessant need for speed and needing to get into the air within six thousandths of a second after getting your aircraft out of the case?
For me, an alloy threaded, self tightening prop with the addition of a locking divice gives a good mechanical union between motor and prop. It additionally gives two levels of redundancy.
One - the props are self tightening in the direction of rotation so each acceleration of the motor tightens the prop.
Second - Should for any reason the prop become loose during flight, the lock will prevent it from back spinning and coming off the thread.
The threaded props are metal against metal using a CNC machined thread/hub.
The QR system relies totally on a press formed spring and ONE tiny, tiny plastic lug from injection molded plastic inside the prop hub to keep your few thousand dollars in the air.
I should add, this is my own view on things and I will never be using any form of "Quick Release" anything on something I put airborne either whilst I am acting commercially or whilst flying for a hobby.

 

[Aviator]

OK, here's my take on the whole situation (again).
Personally I have never liked the QR prop system and have never used it. The 'Free Props and hubs' went straight to landfill.

Redundancy is good in the aviation world and if its possible to have multiple redundancy then better still.
What is this insessant need for speed and needing to get into the air within six thousandths of a second after getting your aircraft out of the case?
For me, an alloy threaded, self tightening prop with the addition of a locking divice gives a good mechanical union between motor and prop. It additionally gives two levels of redundancy.
One - the props are self tightening in the direction of rotation so each acceleration of the motor tightens the prop.
Second - Should for any reason the prop become loose during flight, the lock will prevent it from back spinning and coming off the thread.
The threaded props are metal against metal using a CNC machined thread/hub.
The QR system relies totally on a press formed spring and ONE tiny, tiny plastic lug from injection molded plastic inside the prop hub to keep your few thousand dollars in the air.
I should add, this is my own view on things and I will never be using any form of "Quick Release" anything on something I put airborne either whilst I am acting commercially or whilst flying for a hobby.

It begs the question, if the self tightening props with the prop locks are so successful, why did DJI feel the need to produce the QR props and at the same time stop supplying the self tightening ones?
If I could still purchase the self tightening from DJI then I would probably make the change to them,
However, I have only ever flown with the QR props as they were supplied with my bird and although I can understand many of the reservations echoed by members on this forum, I have had no problem with the QR system to date.
Does anyone know what led DJI to change to the QR system??

 

[miragecy]

I guess it's because of vibration problems... prop locks have slight imperfect differences which leads to vibrations...I've seen this myself. Also self tightened props are suffering from balancing, new props are way much better made.

Andy

 

[Scotflieger]

It begs the question, if the self tightening props with the prop locks are so successful, why did DJI feel the need to produce the QR props and at the same time stop supplying the self tightening ones?
If I could still purchase the self tightening from DJI then I would probably make the change to them,
However, I have only ever flown with the QR props as they were supplied with my bird and although I can understand many of the reservations echoed by members on this forum, I have had no problem with the QR system to date.
Does anyone know what led DJI to change to the QR system??

I understand that the move from self-tightening started when users reported loss of propellers and crashes under heavy braking. The I1 uses the motors to rapidly slow the propellers to give a fast reaction. Some users were probably over stressing this ability. This led to the plastic locks and, in an over reaction by DJI, to the QR design. Like Editor I am sticking with a set of self-tightening propellers (carbon fibre without locks) which have served me well from shortly after I started flying the I1.

 

[The Editor]

It begs the question, if the self tightening props with the prop locks are so successful, why did DJI feel the need to produce the QR props and at the same time stop supplying the self tightening ones?
If I could still purchase the self tightening from DJI then I would probably make the change to them,
However, I have only ever flown with the QR props as they were supplied with my bird and although I can understand many of the reservations echoed by members on this forum, I have had no problem with the QR system to date.
Does anyone know what led DJI to change to the QR system??

Some would say, it was a way of generating revenue by designing a consumable item which may not have been so frequently replaced with threaded props.
Additionally, DJI always strive to innovate (not a bad thing) and come up with ideas which they push to market which may not always be the best option (that is a bad thing).
With regards to prop balancing - I never put any prop on my aircraft that I have not checked/balanced.
I have not experienced balance problems using prop locks since the lock is located over the hub and not likely to cause tracking issues for the blades.
I replace my bearings at or before every 100 flight hours in any case and this regime is itemised in my ops manual which is lodged with the CAA.

At the end of the day, it is a personal choice and we could debate for months the relevant pros and cons of prop securing, prop material, length, chord or color for that matter.
I am happy with the level of safety, redundancy and flight dynamics the original props give me.
If individuals are happy and feel confident in what they are flying then everyone is happy! - or are they????

 

[Aviator]

I understand that the move from self-tightening started when users reported loss of propellers and crashes under heavy braking. The I1 uses the motors to rapidly slow the propellers to give a fast reaction. Some users were probably over stressing this ability. This led to the plastic locks and, in an over reaction by DJI, to the QR design. Like Editor I am sticking with a set of self-tightening propellers (carbon fibre without locks) which have served me well from shortly after I started flying the I1.

Thanks for the explanation, that does make sense to me..

 

[Ward Paterson]

I was doing some calculations today on the braking force applied to the props when a 3.4kg inspire is travelling at around 80kph max speed. The force applied to "each" prop is about 5kg force, for it to stop within 5m of the point at which you release the pitch (in GPS mode). Imagine hanging 5 x 1 ltr bottles off each of those little plastic hubs....

I understand though, this is not possible in GPS mode. These speeds are only possible in ATTi, and in this mode no braking will be applied anyway.. However you have to assume someone could be in ATTi mode and want to stop quickly. To do this would be to switch to GPS mode (worst case), making this scenario a possibility..

 

[Ward Paterson]

Well, it looks like RimTai are taking this seriously. They are conducting their own testing. Here is their test mule up to 6.6hrs of flight

I don't think this thread should be a "sticky". Its not worthy. DJI propaganda at its best.

 

[gray52]

I guess it's because of vibration problems... prop locks have slight imperfect differences which leads to vibrations...I've seen this myself. Also self tightened props are suffering from balancing, new props are way much better made.

Andy

This must be why my ally QR hub and props has virtually no vibration compared to my old stay set up. I do prefer the new style props now I have the new ally hubs.

 

[Mopar Bob]

Anyone had any luck finding a suitable torque wrench (that doesn't cost $1,000 USD)?

So it seems reasonable to conclude that any failures are likely due to over tightening of the hub?

I'm starting to think the folks that were hoarding screw on props are looking like geniuses.

Yes. Do a search on "wiha 28581". They are available from Amazon, and many other places. Amazon has them for $108.

 

[JohnHan]

Yes. Do a search on "wiha 28581". They are available from Amazon, and many other places. Amazon has them for $108.

Thanks.