×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Connect engine to propshaft (RC Boat project)

Connect engine to propshaft (RC Boat project)

Connect engine to propshaft (RC Boat project)

(OP)
Hi, got my hands on a sc32 engine which are originally for planes. Im trying to fit it into a rc boat, i can manage to get it to fit all the servos (electrical) etc. Basically i want to know what the best approach would be to connect the boat propshaft to the engine, the engine has a 1/4 unf thread which originally was for a propeller to be bolted on. The boat propshaft is thin bar i dont know the size as i have nothing to measure it with but originally the propshaft was powered by a cog from the electric motor connecting to the propshaft. How can i connect the propshaft to the engine? thanks

I have attached a few photos. the engine, the propshaft and what i would like to achieve.

RE: Connect engine to propshaft (RC Boat project)

(OP)
Been to the closest RC shop to me, has swapped an plane engine into a rc boat before, he suggested machining new parts and to look online, looked online cant seem to find any other answer, thought i would try here.

RE: Connect engine to propshaft (RC Boat project)

"The boat propshaft is thin bar..."

What RPM will this be running when you're done? Spinning a thin bar of any length at (for example) 10,000 rpm will probably indicate the need for prop-shaft supports.

Apologies in advance if this is something that you've already considered and accounted for.

RE: Connect engine to propshaft (RC Boat project)

if you send me some detailed measurements, I can try printing you an adapter on my 3D printer (ABS plastic)...if you want to try that. I'm picturing a 1/4" nut enclosed in a plastic shell which interfaces directly (splined fit) to the plastic gear shown at the end of the propshaft. Giving enough engagement w/relatively coarse resolution of my printer might be the hard part (that and strength considerations). The next idea that comes to mind is to interface directly to the propshaft or make an alternate endpiece for it.

Worst case the plastic part fails and you have a design to replicate in metal?

RE: Connect engine to propshaft (RC Boat project)

Unless this is an open cockpit boat where flowing air will be able to draw heat away from your engine, overheating may become a problem. Boat specific RC engines usually have a chiller attached to them that use flowing water drawn from the lake/river/ocean that the boat is in to cool the engine. This is one of the reasons why boat motors are typically more expensive than airplane engines - there is more to them. I'd suggest getting an appropriate engine that was designed for a boat instead of trying to adapt one from an airplane. In the end it will be a lot less frustrating and considerably less work.

Maui

www.EngineeringMetallurgy.com

RE: Connect engine to propshaft (RC Boat project)

Aren't you going to have to gear the thing down anyway? Doubt the RPMs of an airplane propeller are going to translate well to a boat propeller in water. Connect them with whatever you end up using for a gear box.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Connect engine to propshaft (RC Boat project)

Couple of questions:

What speed do you anticipate having to stay under to prevent cavitation? Or, reversing the problem if you are assuming a fully cavitating prop, what speed is the engine and what is the optimum prop speed?

Do you anticipate vibration problems in either?

Any significant Sealing problems between prop shaft and hull? (Sorry, its the submariner in me getting all technical here, but water getting in the boat doesn't make me comfortable ...)

Could you simply clamp a hollow rubber tube between the motor shaft and prop shaft?

RE: Connect engine to propshaft (RC Boat project)

Why not use a small piece of srinkable tubing, and attach it, then srink it?

I saw this in another hobby application with an electric motor, and a piece of all thread to make a linier mover.

I doubt you can use windshield fluid tubing, but you would not need to srink that.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources