Folding props

[BigAl07]

I have been flying my P3P Commercially for a year now (and other UAS before that) and I have yet to take the props off for the first time. I have flown from deep in the woods (We do Search & Rescue in 3 states), out in the Atlantic Ocean from a fishing trolley, from the side of a ski slope, from the top of some of the tallest mountains on the East Coast and just about anywhere and everywhere you can imagine. I've yet to take the props off for a single moment.

We modified an existing "tactical" backpack (aka hacked it to pieces technically) and made one that would haul the Phantom with props ON it when we were hiking in the mountains for a client last fall. The one backpack was just for the aircraft and Tx and my wife (safety officer/visual observer/HR lol) wore another backpack that carried batteries, and support equipment. The trick was making a system to where everything was easily accessible yet still securely mounted to our body for the hike. Thank goodness that was a "one and done" job because hiking for hire is not something my body was designed for LOL.

While folding props LOOK cool and potentially meet a NEED they also introduce a LOT of variables into the power train in terms of reliability, performance, and SAFETY! Keep in mind that you're adding more pieces, moving parts, and additional "connections". These are added points of failure and if your aircraft loses a prop, has a malfunctioning prop or anything else it's coming down in a very uncontrolled manner and quickly. Propulsion isn't a place where I'd experiment. As always YMMV but try to keep the "System" intact as designed as best you can because it's designed to be an excellent AP system and when you modify one area you are likely to compromise another.

Good luck and safe flights.

 

[Vertigo]

Well there is at least one poster in this thread who based on his assumptions sees no problem. Maybe you can ask him which ones he has or uses?

I said I saw no fundamental reason. I have no experience with folding props on the phantom, so I have no specific recommendation, but I can refute the claim that they will fold in flight due to "motor braking".

There might be other valid concerns, but Ive not heard them. And Im sure there are bad props on the market, and clearly, a 3 blade prop is always a bad idea on a MR. Folding props however, are the default on higher end multirotors, including DJI's very own S9000/S1000. So its not like it can't work. If a larger backpack or removing props is not a solution for the OP, then he will just need to find good folding one's, and I cant help him with that.

 

[Meta4]

I keep reading that, yet have never seen any evidence that the phantom has motor braking. Everything Ive seen suggests this is just a misunderstanding of the 'active braking' setting (which has nothing to do with motor braking, but configures how aggressive position hold works).

If that was the case, DJI wouldn't have had to develop the composite hubs needed for the P3 series.

 

[happydays]

 

[Vertigo]

If that was the case, DJI wouldn't have had to develop the composite hubs needed for the P3 series.

Oh, that couldnt possibly be because a plastic hub is cheaper, lighter and actually a more secure fit onto a metal thread?

If it actually had motor braking, the prop would most almost certainly have to be bolted on or fixed with an adapter, as the current friction fix would not be enough to keep them in place. And you'd notice when you disarm the quad or when doing throttle bursts. Here is what actual motor braking looks like (second part):

The phantom does nothing of the sort.

 

[N017RW]

One could argue the extent of the braking I suppose... but is is specified by DJI and resulted in a different prop composition/construction for those models. Beyond that there's no reason for me doubt it.

I have noticed there are posters who will argue around the periphery or minutia of anything for some reason. Even published materials from manufacturers. They 'dig-in' and then have to double-down to maintain the position they've established.

In some cases they do so solely relying on unsubstantiated 'facts' as they see them.
Such as: "If it actually had motor braking, the prop would most almost certainly have to be bolted on or fixed with an adapter, as the current friction fix would not be enough to keep them in place."

This is linked to the logical fallacy of 'argument from incredulity'... or paraphrased simply as: I don't believe it so it can't be true.

Using a different product or manufacturer to demonstrate their implementation only proves there is a difference in implementation and not the absence in DJI's P3 & 4s.

So it seems anecdotally that the composite hub prop design provides the amount of 'stick-tion' needed to counter the level or extent of braking DJI has provided in the P3s.

 

[RedHotPoker]

The @dji folding props are cool. I love those 17" bad boys...
DJI E1200 - Tuned Propulsion System

RedHotPoker

 

[Vertigo]

but is is specified by DJI

Where? Ive never seen it, I asked like a bazillion times, and all Ive gotten each time was the "active braking" misunderstanding and plastic props. So can you finally show me some actual evidence where DJI claims they use motor braking?

 

[RedHotPoker]

Active Braking
DJI ESCs support Active Braking, a feature that increases agility and conserves energy. Put plainly, what Active Braking does is to increase the motor’s voltage when braking is initiated so that the time and distance before the aircraft slows to a hover is minimized. While the braking is happening, the motor is automatically put into generator mode so that instead of its mechanical energy being turned into heat energy and going to waste, it is turned into electric energy that is sent back to the battery, charging it up.

The Active Braking feature increases flight performance and efficiency. To further increase the agility and responsiveness of the aircraft, DJI ESCs run at high frequencies that more accurately translates the pilot’s control signals to instructions sent to the motors so that flight is smooth and response immediate.

RedHotPoker

 

[N017RW]

This passage:

"DJI’s powerful air braking mechanisms stop your Phantom 3 instantly , making it hover in place as soon as you release the control sticks."

Can be found at the bottom of this page:
Phantom 3 Professional - Let your creativity fly with a 4K camera in the sky. | DJI

 

[RedHotPoker]

Yup, there is plenty of documentation on this elsewhere as well.
The Best Drones
"Overall, the Phantom 3 is a much better flyer than its predecessor. The new ESC motors use what DJI calls “active braking” (when you reduce throttle, the drone actively reduces motor speed instead of just cutting power and letting the props slow down); in practice this means that at full tilt the Phantom 3 can stop on a dime, which prevented us from crashing it headfirst into a window or two."

Do a web search... ;-)

RedHotPoker

 

[Reed L]

must be ready for flight as fast as possible whilst wearing gloves?

If you want to be able to leave the props on then it's the backpack that you should be looking at. I've thought about folding props but just don't have a use for them. One of the guys on here did a review on a Shoulder Strap Back pack and I think I found it and listed it first below. With these, you will have the fastest access in the bush, and that's what you're looking for. Folding props could be a help with this backpack but really aren't needed. Basically, you want the fastest access, so your rc will need to be intact and put together if you want a chance at the shot you are looking at. Try one of these -

 

[Dheorl]

Although, as mentioned in the very first post, I wanted to try and keep this thread away from why not to use them and simply focus on which is best if you have to use them, that has clearly failed, so here goes nothing...

The main objection to folding props seems to be the fear that active braking may cause them to fold during flight. With that in mind, is there no way to simply turn off active braking? I have no need for my drone to be able to stop on a dime. I'll be flying it around fairly lifeless mountains, and if I can't avoid those then no amount of active braking is going to help me.

 

[Vertigo]

This passage:

"DJI’s powerful air braking mechanisms stop your Phantom 3 instantly , making it hover in place as soon as you release the control sticks."

Can be found at the bottom of this page:
Phantom 3 Professional - Let your creativity fly with a 4K camera in the sky. | DJI

That is NOT motor braking. That is perhaps more accurately described as counter steering, countering the quads forward velocity by leaning backwards, which is clearly what the "active braking" setting in the app does.

Redhotpoker's quote is more relevant but honestly, still at the very least dubious. However wrote that didnt understand what they where writing. Increasing the motor voltage? And "the time and distance before the aircraft slows to a hover is minimized" again refers to the above.

This paragraph however, "While the braking is happening, the motor is automatically put into generator mode so that instead of its mechanical energy being turned into heat energy and going to waste, it is turned into electric energy that is sent back to the battery, charging it up." provides some evidence for your claim. Again though, that is not motor braking, that is turning the motor in to a dynamo. Motor braking requires energy. Which is one reason why it would be a stupid idea on something like a phantom. I guess what DJI is doing will slow the prop down faster than just freewheeling, but I cant see this as a major concern for props flying off.

 

[Dheorl]

If you want to be able to leave the props on then it's the backpack that you should be looking at. I've thought about folding props but just don't have a use for them. One of the guys on here did a review on a Shoulder Strap Back pack but I couldn't find his. But I found another on Youtube. With these, you will have the fastest access in the bush, and that's what you're looking for. Folding props could be a help with this backpack but really aren't needed. Basically, you want the fastest access, so your rc will need to be intact and put together if you want a chance at the shot you are looking at. Try one of these -

Thanks for the suggestion. Unfortunately I also need to be carrying crampons, ice axes, food, clothing, ropes, climbing gear, a helmet. The conditions I might find myself in also require that the drone is inside something.

 

[N017RW]

Sorry for taking the thread off-topic or at least participating in it.

I will not argue what DJI might mean, if anything, between 'air braking' and 'active braking' as I attribute it to language differences and the context or 'audience' the info is aimed at.

 

[N017RW]

Types of Braking in a DC Motor | Electrical4u

#1 sounds most like DJI's implementation.

The world is not always B&W.
There may be many other techniques as well as those which blend two or more techniques to get the job done.


I'm sure there's many more articles available.

 

[Vertigo]

The main objection to folding props seems to be the fear that active braking may cause them to fold during flight. .

Thats never going to happen, even if you have real motor braking. Centrifugal forces will always keep the prop extended. Slowing it down or speeding it up makes no difference. I guess the only concern is that the metal hubs could fly off if indeed the phantom brakes the motor significantly.

There is a setting in the DJI app that lets you configure active braking, but whether that only impacts its "position hold strength" (counter steering, leaning back whatever you call it) or also the regenerative motor braking, I fear no one knows.

 

[N017RW]

I think 'folding' is the hang-up here. There's every reason to believe they may pivot at the root which is what likely contributes to the unstable performance some have mentioned. Folding completely or partially back... agreed not something I would expect.

 

[noki49]

I think putting on your props is the least of your worries in geting set up to fly.
I think setting up your controller with your choice of screen could be far more challenging in a difficult environment, and I haven't seen a case that fits a controller with a screen already mounted.