steam engines

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Re: steam engines

by TDR » July 17, 2013, 12:52 pm

I have an vintage live steam Tug that I would like to fire up again and would like to run with other steamers in the area. (Port Huron or S.E. Mich. area)
Any leads would be cool.
Thanks in advance.

Re: steam engines

by Rentsch » June 30, 2013, 10:32 pm

Paul A:


Thanks for your note, appreciate your comments.

The end cover for the boiler has a manifold which is a superheater or an economizer. The tank on the engine is also an economizer used as a feed water heater which takes the place of the real life condenser.

We found out early that boilers in scale are hard pressed to furnish enough steam for small engines as nothing is efficient and we are dumping the heat to the atmosphere. For that reason we planned for both use of flue gas heat and exhaust heat to assist.

AR

Re: steam engines

by Paul A » June 30, 2013, 9:09 pm

Very nice work! Thanks for sharing. The lube distributer looks great. Am I right that the circular tank next to the boiler with the tubes within is the feed water heater? Is it an economizer?

Re: steam engines

by rentsch » June 30, 2013, 3:43 pm

Here are some pictures of the Stuart Turner reversing twin engine
with feed water heater and propeller.

AR
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IMG_1308.JPG
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IMG_1301.JPG

Re: steam engines

by rentsch » June 30, 2013, 12:33 pm

Lubrication is indeed important, lack of it can spoil a lot of hard work. We are using Displacement Lubricator with light steam oil, bearings, eccentrics and crossheads fed with 7 tube central lubricator. Both run for about 8 hours on a filling.

Injectors in scale size are very inefficient and also require an operator, no good for R/C

Boiler pictures here:

AR
Attachments
Boiler with flue box incl. superheater
Boiler with flue box incl. superheater
IMG_1300.JPG

Re: steam engines

by rentsch » June 30, 2013, 12:20 pm

Lubrication is indeed a very important point as lack of it will kill a lot of hard work. We are using a displacement lubricator with Steam Oil and a 7 tube central lubricator for the bearings/crossheads/eccentrics. Both will operate quite a long time without attention.

Boiler pictures attached as requested. Will post engine pic later

Injectors are in scale size are very inefficient and require an operator thus no good for R/C.

AR
Attachments
IMG_1299.JPG
IMG_1300.JPG

Re: steam engines

by steamer » June 29, 2013, 7:15 pm

One problem not to be overlooked is how to lubricate the engine. On a stationary or locomotive model the "engineer" can get to model with an oil can. On and RC model ship this process must be automatic. One way to accomplish this is to use oil cups with wicking to slowly administer the lubricant. For the cylinders inline oilers are available or easily machined out of bar stock. These are placed on the steam inlet side of the engine. Viscosity of the lubricant is also important; too thin, with the heat of the engine and the oil quickly runs out. For the cylinders, steam oil should be used as it holds up in saturated steam. Please post pictures of boiler.

Re: steam engines

by 1guest » June 29, 2013, 6:37 pm

Why not use an injector. No moving parts and doesn't rely on main engine for feed water.

Re: steam engines

by rentsch » June 28, 2013, 11:17 pm

In this case it was easier to have separate pump to allow for adjusting volume and repairs but bi directional output was necessary to pump when reversing. Double action pump would also be suitable. Crosshead driven pumps ruled out as they run too fast for the valves.

Boiler pressure about 80-100 psi. is the plan for now.

We have looked at throttle valves for RC - yes, you are correct. The Ball or Barrel type valve is best suited I believe as:
They are balanced and force to operate is nearly same over entire range. Actually using the design on the 2 cyl. tug engine in the Duluth Maritime Museum. They can be made with non linear opening so that just cracking open will give slow speeds and finer control.

AR

Re: steam engines

by 1guest » June 27, 2013, 10:34 pm

Would a simple ball or barrel type valve work well for a throttle valve? You state that the feed pump works in either direction as the engine is reversed, this would be important in a tug model. What psi does your boiler operate at?

Re: steam engines

by rentsch » June 27, 2013, 9:29 am

We have built a 6" dia 8" long Scotch -Ingliss type firetube boiler and plan to use liquid fuel although butane is also possible. Pictures are available if you are interested.

The Boiler is from Harris book on boilers and has a shell of 1/16th Monel. The feed pump is engine driven with a worm gear reduction to a 3/8" bore plunger pump, drives in either direction from a cam.

Feed water heater on engine exhaust looks like a condenser, removes oil from condensed steam. Water is dumped as tanks in bow and stern are large enough for several hours running.

AR

Re: steam engines

by tinstack » June 27, 2013, 4:24 am

What size and type of boiler would be suitable for use with the stuart twin engine. Also what type of fuel would the boiler use, gas or liquid?

Re: steam engines

by rentsch » June 24, 2013, 8:20 pm

A twin is best as it is self starting for R/C with 90 deg cranks. compound is 180 deg and has dead spots. If you wish I can send you pix of my engine if you send me your e-mail address.

The Stuart Twin is best bet for larger models, fits 48 to 60" quite well. Machining time is about 250 hours though.

AR

Re: steam engines

by tinstack » June 24, 2013, 12:13 pm

How would a twin compound engine word in a r/c model?

Re: steam engines

by rentsch » June 20, 2013, 7:00 pm

Just working on a Stuart Turner Twin for an R/C Tug in 3/4" scale.

What are you interested in? Turbines are out of the question in models.

AR

steam engines

by Guest » June 9, 2011, 11:58 am

anyone ever built and larger steam engines or turbines for rc models?

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