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Question High capacity and long travel dedicated heave axis ideas

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Trip Rodriguez, Sep 27, 2019.

  1. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
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    Location:
    Lake Ariel, Pennsylvania
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    My Motion Simulator:
    6DOF
    Hey guys,

    I've been super busy with crazy real life stuff and haven't had time to touch my sim for a couple months now. I expect this trend to mostly continue for the next year or so, and then after that my schedule should relax pretty drastically making time for my hobbies. Anyway, somewhere most likely within six months to a year I'm going to have to fully dismantle my simulator and move it from my Dad's basement to my own much smaller house. When I've got a little time to think, usually when driving and such, I have ideas flying around my head and ideas lead to questions.

    I mostly use my simulator for flight rather than racing, and my favorite axis is heave. I love my touchdown bump, and strongly desire the large smooth heave cues that I have experienced in real world light aircraft. Every time I ride in an elevator I get heave envy and want to put my sim inside one!

    I'm thinking that when the time comes I might give up the 6DOF and go with a really, really good G-seat build plus a bit of pitch, roll, and yaw motion and as big as possible a dedicated heave axis.

    So the question is; what kind of setups would you guys recommend for a smooth but fairly fast dedicated heave "elevator" that the entire simulator sits atop? It would have to have quite a lot of capacity for weight since the cockpit, pilot, g-seat, and 3DOF sim would be sitting on it. I want a minimum of 14 inches of heave travel. I figure using springs to support the load at the mid point would probably majorly reduce the power needed for the heave axis. EDIT: Actually it rather makes sense to adopt the design of actual commercial elevators with a counter-weight. Or does it? What we are concerned with is acceleration, and with a counterweight we need to accelerate twice as much weight don't we! These things make my brain hurt!

    If I keep my current equipment rather than sell and start over I'd theoretically have three 3/4 horsepower AC motors and drives available for the heave axis. I'm not sure about using multiple motors to move a single mechanism though, thoughts? I don't want three separate drives that can get a little out of sync on the heave axis, they'd have to be all "locked" together if that makes sense. Examples would be to have three motors on three VFD's all driving the same belt. All three motors using the same sensor. Is that kind of thing practical?

    I am also considering selling my current VFDs/motors/gearboxes/bellcranks and starting from scratch to get something quieter. If I go that route I could replace the three motors/drives with a single much larger motor and have only four motors total, not including the G-seat motors.

    This is mid or long term planning, I don't expect I'll be doing anything with this for at least nine months but I'm hoping for you folks to maybe help me with the brainstorming sessions I'm having when I get a little quiet time.

    Thanks for any advice,

    Trip
    Last edited: Sep 27, 2019
  2. BlazinH

    BlazinH Well-Known Member

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    For flight sims where you need smooth acceleration counterweights work quite well. If a platform is almost perfectly balanced then it takes about the same amount of power to move either up or down so it makes tuning quite easy to make motion fluid. When it comes to road surfaces or turbulence though the inertia of counterweights can cause some issues. For that its better to use something other than weight to counter with like extension, compression, or gas springs.

    It may work for some time but without syncing the motors it will inevitability put more stress on everything. If the belt allows some slip though this would help reduce it.
  3. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    484
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    2,492Coins
    Ratings:
    +207 / 3 / -0
    My Motion Simulator:
    6DOF
    Thanks guys! For some reason I didn't get notifications of the replies, so sorry about the delay.

    I realized that once I have the G-seat and don't need to use so much motion on the 6DOF getting it smoother should be easier and having 6DOF is certainly desirable, I'm just getting frustrated. Maybe I'll build linear actuators for my current VFD/Motor setups. If I'm going to continue to have to drown out the VFD whine with loud headphones anyway I might as well have noisier mechanicals too!