Nosewheel steering servo

__Evan__Evan Club Members Posts: 1,122
Hello everyone,



I'm hoping to get some advice on the steering servo for a UAV-3000. Other people seem to be using really big servos (10kg-cm or more), and I'm having a bit of trouble understanding why. As far as I can tell there should be next to no torque applied on the wheel during takeoff/landing (mainly because the strut is vertical, so there's no arm for the torque to act around).



Could someone clarify whether I actually need a big servo here? I've got a fancy Hyperion DH20X coming at some point, but it could be a while - and I've got a brand new HobbyKing HK15138 here that's just waiting to be used for something.



Thanks,

Evan

Comments

  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    It's only my guess but nose wheel steering planes I've had that servo gets some pretty solid wrenches and shocks, especially once the leg gets a bit bent and that being a nearly five and a half kilo model those shocks and wrenches are going to be fairly savage maybe. On the other hand I've buggered up numerous of those legs and even more of the control arms that attach to them on .46 size glow models but can't remember ever buggering one of the servos.I do usually use a bigger, stronger metal geared one for that usually though, HS 645MGs the last few times.Sawdust2014-11-30 21:07:10
  • WTWUKWTWUK CornwallClub Members Posts: 13,605 ✭✭✭
    And there is the possibility of wheel shimmy - high frequency wobbles that can wreck less powerful servos.



    On real aircraft, the jacks/motors that control nose gear steering are quite surprisingly powerful for that very reason.



  • __Evan__Evan Club Members Posts: 1,122
    Great, thanks for the responses. I guess I'll wait for the Hyperion one to turn up.
  • WTWUKWTWUK CornwallClub Members Posts: 13,605 ✭✭✭
    And you certainly won't be disappointed with that one - Hyperion servos really are beauties, and if they still have the 'exchange service' in place for even crash damaged servos, even more impressive! WTWUK2014-12-01 09:17:10
  • __Evan__Evan Club Members Posts: 1,122
    Yes, I've got a lot of Hyperion servos now. When they're as cheap as those ones were ($6 - $15) it'd be silly not to buy them. Got an Emeter2 as well for at-the-field adjustments to speed and trim.

  • WTWUKWTWUK CornwallClub Members Posts: 13,605 ✭✭✭
    Yep. Tje programmability makes for very east setups. They ate the only servos I have fitted to my helis that allow absolutely zero trim setups, resulting in lovely balanced helis.



    Must get some more! Heh heh!
  • __Evan__Evan Club Members Posts: 1,122
    At some point I really should pull one apart and have a look at the hardware inside them. There's got to be a microcontroller in there, presumably with the UART connected to the signal wire (for programming). I suppose that you could set up an autopilot so it programs individual servos for trim/speed, which would be pretty cool.

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