My first steam engine

[quinten1231]

Hello all

AGAIN I have a question, I am about to order a new flywheel for my ST 5A and I am not sure about the weight. At the moment I have a solid flywheel of 2.3kg (5 pounds) and 133 mm diameter which is badly machined and has a wobble.

The new flywheel I am considering is a spoked one with a final weight of about 1.8 kg (4pounds)but a diameter of 150mm.

Now the question is: will this flywheel still have sufficient weight for boating application since the diameter has increased which (according to my thinking) allows for a reduction in weight to have the same effect as a smaller heavier one?

PS: I know that there are stuart flywheels meant for the 5A but personally I think they are too big, if iI remember correctly the stuart ones are 7-8 inch (180-200mm)

Kind regards Quinten Versluis

[DetroiTug]

When the engine is coupled to a shaft and propeller, the flywheel weight is not as important. A smaller and lighter spoke wheel should be fine. I ran my engine with no flywheel, I only added it as a test to resolve an engine shaking issue and to add some weight plus have something to grab and turn the engine when adjusting valves etc.

-Ron

[quinten1231]

Ron

Perfect, thank you for your reply.

Regards

quinten

[Edward]

Dear Quinten

The main reason that single cylinder engines have flywheels is so the energy stored in the flywheel will carry the crankshaft, and therefore the piston , past top and bottom dead centres and so allow it to run properly .
This doesn't apply for a marine engine since the motion of the boat means that water passing through the propeller will turn it and so also turn the crankshaft and carry the piston past the dead centres .

BUT... there is a very good chance that on stopping the piston will end up at one of the dead centres so there is still a requirement to bar (turn) the engine past the dead spot when you want to restart , so some sort of a flywheel or barring wheel is needed . It doesn't need the mass of a land based engine's flywheel because as explained above its purpose is slightly different .

So you can choose how big you want it to be to be convenient to either kick or turn by hand to get off the dead centres . If you opt for a solid wheel it is usual to drill a series of holes around the circumference so you can put a bar in to turn the engine with precision if you need to adjust the valve timing etc .

Regards Edward.

[quinten1231]

Edward

Thank you for the detailed explanation, I completely forgot about the influences of the water flowing through the propellor, i was solely fixed on the idea of whether it would be able to pass top and bottom dead centres.

I decided to order a similar flywheel as the one described earlier, same size but slightly lighter (1.5kg) but a much nicer design, in my opinion.

Regards Quinten

[Lopez Mike]

Thank you Edward. Exactly to the point.

My propeller has more than enough mass to carry the engine through centers at very low speeds but I have made sure that the flywheel is convenient for a quick boot when maneuvering in close quarters.

Also, I have a very small magnet epoxied to the flywheel where it isn't obvious. It triggers a bicycle speedometer calibrated so that 1000 rpm equals 100 mph (100 k.p.h. would be fine). Pretty much the only electrical device on board if I don't count a flashlight and a hand held marine radio.

(I have this vision of someone reaching over the stern to move the wheel by hand. Horrors!)

Mike

[DetroiTug]

A few years ago, I was grappling with the +/- flywheel question. I went up to a steeper pitched prop and the engine was shaking. I added the flywheel last year on suggestion that it could be the long propshaft twisting like a torsion spring. Then this spring the prop was increased from a 20X20 3-blade to a 21 X23 4-blade, the shake returned above 70 psi. I set up a test with a pry bar against the side of the boat against the engine and then flexed it. I set up indicators and found out that the engine mount made of 1/2 X 2 solid steel was flexing. I couldn't believe it. So, I welded some gussets in it and no more flex and no more shake at higher pressures.

-Ron

[Lopez Mike]

My little 3 x 4 single is sitting on a couple of 2 x 4 studs spanning perhaps a three foot spacing between frames. The shaking from 350 rpm up has to be seen to be believed.

Needless to say, there are new steel channel motor mounts in the pipeline.

Mike

[quinten1231]

Hello

I have some questions... Again.

I have stripped the engine of its paint and would like to repaint it, however I cannot find the color I am looking for which is heat resistant, Yes I know I should have thought of that before stripping it but I assumed that it would be an easy color to find.

Now my main question is, how hot does a steam engine get? More specifically the steam chest and just below the cylinder. The base I am not worried about.

What paint have you used? 1k-2k, sprayed or brushed?

The two colors which I am looking for are a bright creamy-beige, and brown.

I have found plenty which are only resistant up to 120-150 celsius, but I am sure that is too low, I assume that I should look in the 2-300 celsius range but thats going to be a challenge, andnwould make my life significantly harder.

I have searched all over the place and I only found one heat resistant beige made by krylon (never heard of them) and non of them ship to EU, and I couldnt find an example of the beige they offer.

I also wouldnt mind having brush paint, since I find the finish nicer (without brush marks ofcourse)

Regards Quinten

[DetroiTug]

Regular "Engine enamel" is fine and available at auto part stores, priming is not necessary. The engine will get as hot as the steam, typically, that's 300°F or below.

-Ron