Folding Propeller Stuck During Flying (quad motor) , need advice

Hello guys, I plan to build big Vtol Quad plane by using big Folding propellers for the quad motors (36 inch propeller). However I am worried that the folding props may stuck in the air when the quad motor stop during plane mode. I have done some test on the ground about folding props behaviour of a multicopter. I found that some times the props. “stuck” when it stops after rotating at medium or high speed. As we know behaviour of quadplane also similar, that the multicopter motor will stop during plane mode at certain speed. As the folding props may “stuck” during plane mode, then when it change to copter mode than the crash may occur. Why I use folding props ? This is because for big size propeller (36") it is much easier to transport and also easy to find the market. So, I really need advice for solution of this protensial problem that may arise . Any body has experience using folding propellers for quad motors of their VTOL plane? Thank you very much. My best regards.

36 inch props? that sounds like quite a monster of a quadplane. How about posting some photos?

Wow… 36" props! Unless you intend to have all your VTOL motors tilt like this one and equip it with such a heavy-duty tilting mechanism that’ll handle the torque and P-factor during transition, rethinking using folding props might be in order. Even Uber’s eVTOL and Boeing use conventional props. Interesting concept, though, and would be curious on the design.

Good luck.

No photo yet, still concept design though.

This is the interesting parts. I really want to know, why they don’t use folding propellers??? Will folding propellers really create unsolved problems??? (for multi copter parts). I can not find any references about this folding propeller problems on multi copter. I really need to learn about comparison between folding versus non folding propeller. Thanks for any inputs.

Those are basic aerodynamics principles learned in flight training and dealt in detail with aeronautical engineering course. The size and scale of your project would almost require a full time engineer in its concept and design phase. 36" props are seem to be outside the realms of hobby or sUAV grade.

Good luck.

Folding props are ok for a quad when you can manually spread them out. On the fly you would need a spring loaded not yet designed prop. I see too many potential issues to try this VTOL.

Wouldn’t a simple solution be to limit the range the folding props can fold?
That would require making new propeller hubs (maybe even adding reinforcements to the propellers so they don’t wear from hitting the limit).

Or slowly lower the propeller speed while transitioning (I don’t know anything about vtol)

Thank you for your comments guys. Yes this project need serious engineering design. We need to do some testing on the workbench to avoid any problems in the future. But my impression is , it is better to use normal (non folding) propeller for Vtol.

When you said “potential issues” are you referring to the folding propeller issues??

yes, how can folded props start spinning?

So the key issues is how to avoid this folding propellers become folded (stuck) in the air. If we can not solve this issue than I will change to Normal propellers. Thank you.

Do you know who makes a 36" folding prop?

Yes, I bought it from Rctimer

Is there an actual problem? I’ve never seen any report of a folding propellor getting stuck because it wasn’t unfolded before spinning up. I have heard of issues with the type of folding props used on motors for forward thrust but never for multi rotors. DJI’s larger multis have 21 inch folding props on them. I always unfold them but I’ve had other operators tell me it isn’t required. That does seem odd to me so I wouldn’t do it. But it wouldn’t be hard to test on the bench if you want to find out.

Folding propeller may get stuck if we do start stop motor in the air, which is the case of our Quadplane. I did this test on the ground so that I am worried, because some times the props. get stuck when they stop after spinning. For multicopter this is not a problem, because the motor keep spinning. But I think I can install a kind of protection guard at the props. holder to avoid this problem.

Just in case you hadn’t seen these; specifically for large VTOL.

Good luck.

Thank you Rollys, but the price is more than twice of the RcTimer price…

They may be worth it. That’s all I use on my multis as they are top quality and typically provide more thrust.

As I am also into the development of a VTOL, I am curiously following your ideas and approaches. Regarding the issue of folding props, I wonder of you’re talking about horizontally (i.e. in the plane of the blades) of vertically (as in powered glider applications) folding types?
Horizontally folding seem rather unproblematic to me, as they’re applied in many multicopters…