Hijikata

Ok, I am going to be honest, I am not sure exactly where I should post this, but here it goes...


I want to use an older RC Car engine that I have in an airboat (that I will build). This is a 4.8cc engine, and my main question is is their a way to attach a propeller on to it.

I have this engine just sitting around collecting dust and would love to put it to use.

For those who do not know what an airboat is, please look at this link:
[link]http://www.cajungatorairboats.com/id1.html[/link]

Campy

My Feedback: (1)

You use a prop for the airboat. Just bolt the prop in the same place.

Be advised.....you will PROBABLY have to run the engine as a "pusher" type engine unless the engine originally used "pusher" props on the airboat.

If the engine initially used pusher props, the engine will run in a counter clockwise rotation and you can use regular props.

If the engine ONLY runs in a clockwise direction, you will have to use the engine as a pusher engine.

KitBuilder

The engine was originally a car engine.
Don't car engines have flywheels attached.. I don't konw.. just guessing. I would think the main issue is to be sure you prop the motor correctly so it doesnt' spin up to much and over heat or similarly bog down. What is the size of the car engine.

Phlip

He said it's a 4.8cc, which is a .29 ci. I'm not a nitro car guy either, but I think that car engines have flywheels/clutches, sometimes pull-starters, and big heat sinks on the heads. All of that stuff is unnecessary for a plane or an airboat. If you know how to disassemble your engine, figuring out how to mount a prop should be no trouble. If you don't know how to disassemble it, I recommend finding somebody who can help-in person.

Mode One

I wonder if the thrust of the prop pushing one way or the other might not be a problem for a car engine. Isn't the bearing set-up different in a car engine, then a propeller engine? Airplane engines are designed to except loads pulling on the engine in the direction of travel. Car engines are not, as there are no side loads.

JohnBuckner

My Feedback: (1)

Lots of car engines have been used in applications with propellors and it all depends upon your engine and if it does not have a thrust bushing can you get one for it.

Overcooling is also a consideration with the heat sink cylinder heads especially if you propellor application is a tractor configuration. This can be delt with by wrapping foil around some of the fins.

Hijikata

Here is the engine... [link]http://www.rev-line.com/28engine.html[/link]

It currently does not have a flywheel or clutches on it, I removed those and put them on my new engine for my car. I just have this old engine sitting around, it needs some minor work to get it running again. I was going to put a roto start on it. My concern is with attaching a propeller to the end. I am rather new to the RC airplane world, so I don't have any idea how propellers are attached to engines and what makes the airplane engines different than the car engines. I understand the fundamental differences presented here, but I am concerned about attaching the propeller to the crankshaft, I don't exactly know how to do that

Thanks for all the answers so far

JohnBuckner

My Feedback: (1)

That engine appears to have insufficient thread length on the crank even if a thrust bushing were avaliable and that makes a simple conversion impossible. Its unlikely that the factory makes a suitable crank for propellors, you could try but its doubtfull.

In this case you will be better off buying a new appropriate engine for your purpose. Little aero 25,28,32,36's are pretty inexpensive compared to what you paid for that engine.

John

Hijikata

Thanks John!

I got that engine in a RTR Buggy I got for Christmas, had some problems with the engine (hence why it needs some work ) I was just looking for some way to put it to use in a little side project as I would not want to put it in my car ever again (I have a much better engine than that one now).

I will look into those engines you were talking about. I still have to build the hull, etc. for the airboat, but I really appreciate everyones help here

jimmyjames213

My Feedback: (2)

idk how big the threads on the engine are but looking here http://www3.towerhobbies.com/cgi-bin...=GCTWRX&P=0&S= most car engine threads are very small, so you may not be able to fit a prop on it. if you could get a prop on it i would try........a 8x6 maybe but most car engines like to rev. a airplane engine turns around 14000 but a car engine can turn around 20000-25000+ you may need a smaller prop so the engine can unload. i would try a larger prop in the 8x6 area then work smaller, its better to overload the engine than to watch the piston shoot out the cylinder head because the rpm were to high. i havnt tried this before but im thinking about it (aquacraft .18 marine engine) so take my info with a grain of salt

Hijikata

I guess my question is how do you attach a prop to it? I just started getting into airplanes, so I am not exactly sure what makes the prop spin with the engine. I remember seeing something called spinners and stuff, but I see them and I have no idea what they are for.

Phlip

It needs a prop driver. That's the plate that goes behind the prop and has a knurled surface to "dig into" the back surface of the prop. Usually the cranks on aircraft engines have a taper or some sort of means for the crankshaft to engage the prop driver which then mates mechancally with the prop. I'll see if I can find an illustration so you can see what I mean ...

Look at this: http://penn.emaxcess.com/digital_rea...th_cad_018.htm You'll see what I'm taliking about.

JohnBuckner

My Feedback: (1)

As I posted earlier there is insufficient length of crank thread to support a thrust bushing AKA prop driver and a propellor. This is not going to happen unless the factory produces a crankshaft designed to support a thrust bushing or you are prepared to machine your own crankshaft.

Purchase a engine designed for your needs.

John

j.duncker

My Feedback: (2)

You do not need a new crankshaft to do this. You do need someone to make you a prop driver and a special prop nut which will have a projection to go through the prop to get to the threaded portion.

Like this. Nice little project if you have a lathe but if you have to pay for it FORGET IT used engines are SOOOOO cheap.

Hijikata

Do you have any of the specifications on that, my boss has a good friend that owns a CNC shop. I am wondering what kind of a price I can work out.

j.duncker

My Feedback: (2)

No; the pic I showed is of a tiny home built diesel for FF models.

Anyone good enough to machine you a prop driver and prop nut could rough out the dimensions on the back of an envelope in 5 minutes. But like I said if you are paying someone forget it. It would take me 1 to 2 hours to do this on a manual lathe and much longer on the CNC machine because you have to write the program, Computer Numerical Control is great if you want 50,000 but no good for one offs.

Hijikata

Alright, well thanks for your help