nord0306

Hi, I'm trying to build a scale model rc hydrofoil boat to develop a foil system to eventually build a full size model that I can ride in. I am planning to 3d print most of the components and the hull, but I need to buy a motor, servo control, etc. I haven't been able to find kits that include just this hardware. Should i just buy an entire boat that has the correct sizing and just transfer everything to my "hull"? I would like to keep costs down as the main development i need to concentrate on is the foils and control systems for flying.
thanks!
Adam

mfr02

You buy the motor to suit the boat, an ESC to suit the battery and motor under the supposed load. Radios and servos used to be sold as "outfits" but nowadays are sold separately.
Since every project is different, with different requirements, this makes sense. A lot of sellers will put a matching bundle together. A low cost boat might well not have readily transferable suitable parts, usually it costs a lot less to swallow the initial pain and buy the right gear first time.

loopdeeloop

My Feedback: (4)

You start with the control system -- meaning the Transmitter, receiver, and the number and size/power of the servos you need to control this boat. You then need to determine how big and heavy this boat will be and what performance goals you have. That will determine the type of motor (brushed or brushless), electronic speed control (ESC) and the type (LiPo, LiFe, NiCd, etc) and capacity needed to provide the power needed. Transmitters, receivers, servos, batteries, ESC's, motors, and even the drive trains (props, shafts, and support hardware) are all available at on-line or your local hobby stores. Depending on the boat size, you can even power with a nitro or gasoline engine.

nord0306

Thank you for the replies. I need only 2 channels, one for the steering and one for the motor. I'll look into things from that end. My design hinges around integrating the prop shaft into the rear foil, so i was trying to nail down which prop shaft to use. I would like to use a flex shaft so i can drop it out the middle of the hull and support the bushing with the rear foil assembly. Is there a standard size shaft that works with a range of economical water cooled motors?
I'm planning that the boat is about 24" long, but I don't have a good idea on weight. The design will be mostly plastic with some metal hardware. I don't need a really long run time, so a huge battery isn't necessary.
Thanks!

mfr02

Pretty much all shafts sold are a "standard" size, or fall into a range of standard sizes. The props have a matching range of standard fixings (screw thread retained by a locknut or dog drive). For connection to the motor shaft, you get the appropriate coupler with a hole at one end to match the prop shaft, and one at the other to match the motor shaft. It could be a solid coupler, it could have a joint. If this standardization was not the case, there couldn't be a hobby industry where there was a range of manufacturers for the various parts in the chain.
Solid shafts, I have experience of, but have not used flex shafts, so it will need the knowledge of .someone else to get a good answer there. But having seen a few, they are generally high maintenance items - they do need attention after every session and even then, have a shorter life expectancy compared to a rigid shaft fitted with lubricators.

Got RPM

Since I have used flex shafts in high speed boats for four decades I’ll chime in. Solid shafts are obsolete for fast craft due to their inability to change thrust orientation efficiently. Universals are terrible on high speed craft and were abandoned by the hobby almost 40 years ago. Flex cable drives are easy to set up, are very efficient, and have far less maintenance than comparable solid setups.

Typical FE boats 24” in length run 2S or 3S batteries. What speed is the OP desiring? A 0.150” flex cable will be sufficient, but prop and motor will depend on the speed desired. He can either piece together the parts he needs, or he can purchase an RTR boat and use its drive system. Hard to say now which will be the most cost-efficient.

But really, why not just add the foils to a cheap RTR boat? Especially if all you want is to develop you own foil geometry, not waste time on building a boat for them.


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nord0306

Thank you. Got RPM, I will probably just buy a RTR boat and go from there. Worst case, i have a basic rc boat to play with. Thanks.