Home Forums Everything about the Tricopter LR Some technical difficulties… Arms folding back in flight

This topic contains 10 replies, has 5 voices, and was last updated by  Imetomi 2 days, 17 hours ago.

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  • #63496

    fgsfds1234
    Participant

    It’s been a while since a quick test flight, I managed to get some clear space during a beach trip to stretch it’s legs, after about 6 min of just going laps not pushing it very hard my friend starts yelling that a motor is coming loose and to land, right when I notice I have almost no rudder control. Barely manage to stick it in a bush and find the props like this props
    It sounded like the left arm came back enough to contact the tail, even though I thought it was pretty snug in place. The good news is I’m buying more of these master airscrew 8×4.5 cause they didn’t completely shatter on me and lasted till I could land. And they draw a little over 9 amps hovering with a heavy battery a little over 400g, and about 15 amps cruising sort of fast.
    So anyways I think I’m going to try making a piece of something house shaped to go between the two bottom plates to pin in place to lock the arms if they are going to drift forward like that on me. It would be harder on the arms on landing but I need this to be reliable for some long trips in the future. Anyone else have issues with them moving or do I just need to get the screw much tighter before flying it?

    #63497

    danisaez
    Participant

    Hi fgsfds1234,

    I had a crash once due to an arm folding back, so I decided that never again!

    So I made some arm blockers, check them out https://www.thingiverse.com/thing:3679159

    cheers.
    Dani

    • This reply was modified 1 week, 3 days ago by  danisaez.
    #63501

    yumemi5k
    Participant

    Friction is largely the only thing stopping arms from folding during motor braking. I’ll probably also print this later.

    #63505

    Kevin_Erik
    Moderator

    The friction is by design…. adding the holder prevents the arms from folding back during a crash. Sure it’s likely to lose a prop or two but it’s supposed to save the arms / motors from breaking.

    #63507

    danisaez
    Participant

    That’s why I printed the holders in TPU, in order to have some flexibility if any crash should happen, and absorb th shock.

    #63509

    Kevin_Erik
    Moderator

    In the event of a hard crash, the TPU probably wont “give” enough to allow the arms to swing back fully and prevent damage. Besides, your added part adds weight and complexity to what should be a very simple system.

    Currently, all of Davids carbon parts come with a protective coating that makes it super smooth. Your best bet is to increase the resistance to swinging back by making the carbon “rough”. Scratching it up a bit will help reduce your chances of Arm travel due to vibration. Could also add heat-shrink to the carbon arms to make it wider should the swing mechanism clearance be too great.

    #63511

    Imetomi
    Participant

    Kevin_Erik have you tried the heat-shrink method? What about some self-amalgamating tape that I think David used in his Baby Tricopter build?

    • This reply was modified 1 week, 1 day ago by  Imetomi.
    #63517

    Kevin_Erik
    Moderator

    Yes, it makes it near impossible to move the arms, without first loosing the supporting screws. Yet, the arms can still move during a crash, which is what you want to happen. Keep in mind that replacing props is easy. Rebuilding an arm assembly takes about an hour, assuming you have the parts on hand.

    Edit: tape could work, but the heat shrink can fits really tight. In the end, i think this is a matter of preference.

    #63562

    fgsfds1234
    Participant

    yeah fixing it is not ideal, but I think until I can be certain it won’t move on me I’m going to stick something in there. this current design for now, until my printer is up and running I might try this. ideally I could make something that holds it but is frangible in case of a crash, like something that can be pushed out between the front posts after breaking some small tabs off or something.

    • This reply was modified 4 days, 12 hours ago by  fgsfds1234.
    #63566

    Kevin_Erik
    Moderator

    The arms would break long before the insert would.

    #63607

    Imetomi
    Participant

    Luckily mine holds the arms pretty well. If I were you I would simply use some stronger rubber bands and tie them around the arms and the front screw extender. That would probably hold the arms in place while flying and let them move during a crash.

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