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Thread: Advice for Engineering Test Bed Build

  1. #1
    Join Date
    Apr 2020
    Location
    MI
    Posts
    3

    Default Advice for Engineering Test Bed Build

    Hi all,

    I'm looking for advice on a new build. I want to put together a large 36-48" (maybe bigger) mono-hull, planing hull, no frills test bed. The goal is to do small scale (lower cost) development of drive systems and propellers for the real thing. The alternative to an RC build is modifying a real boat so price isn't so much of an issue. Basically I want the beefiest electric power system i can get with off the shelf parts. I need something that can do moderately high speed and also generate a great deal of torque for complicated drive trains and large props. target for max prop shaft speed is 7000 RPM. My current power system plan is as follows:
    Motor - Turnigy AquaStar T20 Brushless in the 1280kv mode.
    ESC - Turnigy AquaStar 200A Watercooled Sensorless.
    Battery - ZIPPY Compact 4500mAh 10S 35C Lipo Pack w/ XT90.
    This all would be run through a gear reduction to give me around 7000 RPM at full power I'm new to toys of this power so a couple of questions. Will these parts to work together reliably? Is there a better component or set of components to achieve my objective. How many of these battery packs should run I for a decent operational time? Finally am I crazy and going to blow my boat up with this kit? Any suggestions comments etc. are greatly appreciated.

    Thanks all!

  2. #2
    Join Date
    Sep 2012
    Location
    Tg
    Posts
    1,438

    Default

    Sadly two guarantees here, the esc and batts will not handle what you want. That motor is an amp hog in delta configuration, and would be 6s max! If you use the wye configuration you will be in a better place for the esc. I don't know that the esc will give you any joy though, you would be better off with the ZTW 300. You need batteries that are 5000 mah and 40c min, and I would suggest paralleling two 10s sets together for 10000mah for reasonable runtime. Gear reductions are a waste of time with brushless setups.
    I have to ask what you are looking to achieve? 7000rpm in a model boat is not going to be efficient no matter how big a prop you use. I have a 45" hull that with a 56mm can motor 650 kv on 10s would run a X460 prop for speeds around 50 mph, that is 24,000 rpm unloaded, approx 20k rpm loaded.
    NZMPBA 2013, 2016 Open Electric Champion. NZMPBA 2016 P Offshore Champion.
    2016 SUHA Q Sport Hydro Hi Points Champion.
    BOPMPBC Open Mono, Open Electric Champion.

  3. #3
    Join Date
    Apr 2020
    Location
    MI
    Posts
    3

    Default

    Thank you for the input peter! Im working on developing an outdrive, and a big one as far as the RC hobby goes. The goal is to run very large custom props at realistic RPM ranges and characterize their performance. Speed is a concern as I need to be able to move across the water in a realistic way but the most important thing is analyzing the hydrodynamics of the props and drive system. I don?t want top speed I want to be able to change my configuration ie. blade count, pitch, trim angle, and see changes and in performance. In pursuit of this I need a power system that will be able to overcome the inertia and and parasitic losses associated with multiple gears shafts and bearings not to mention the large prop. I understand that this is a quite unusual use case but like I said in my original post the alternative is to go much bigger and more expensive. Anyway thank you for taking the time to break it down for me and I hope this makes things a little more clear.

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