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Feb 03, 2020, 11:53 AM
Registered User
bboarder711's Avatar
Thread OP
Help!

Midwest Model IV Steam Engine help


HI everybody,

I am looking for your guidance. I built the Midwest Fantail launch about 8 years ago with the Model IV engine. Sadly I shelved the project due to poor run times. I recently picked it back up again and decided to get it running and increase those run times and actually run the model.

What are your suggestions to get this running again? I think i might be loosing steam between the cylinder and the steam input. I also have the adjustment bolt slightly backed off from full tight.

Currently I am using 2oz of water and 2 Tablespoons of sterno. The best run time I have been able to get is 20 seconds.

Here is a video of it running after the boiler has been burning or about 10 min.
Midwest Model IV steam engine test run (0 min 25 sec)


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Feb 03, 2020, 04:04 PM
Registered User
Hi bboarder 711,
I built this model and steam plant for a magazine kit review many years ago. I had problems in that the steam engine seemed to have little power to turn the propeller when installed in the model, yet out of the model it ran quite well.

This loss of power was traced to two things;
1) The rubber tube used to connect the engine and propeller shafts is a method that can work effectively when the two shafts are inline or very close to being so. The angle between them in the Fantail model design is way to much and absorbs a lot of power. I replaced it with a small Universal (Hooke) coupling which took no measurable effort to rotate.
2) The propeller shaft ran in a close fitting brass tube. Even if both shaft and tube are perfectly straight, there will be a lot of friction between them. Even a well lubricated set up which might reduce friction but then replaces it with viscous drag in the narrow gap between shaft and tube. Like you I hope, my tube was well and truly fixed into the hull and replacement would have been a pain. So, not being an Engineer for nothing, I increased the gap between the shaft and tube. The shaft was clamped in the chuck of an electric drill then spun up whilst resting on a block of wood and pressed down with a file. The ends of the shaft were not filed down so as to create reasonable bearing surfaces just inside the ends of of the tube. I probably only reduced the shaft diameter by a millimeter or so (approx 1/16 inch) but that was enough to reduce friction and viscous drag. By the way only use a light oil in the tube, heavy oil or grease will just add a viscous load on the motor.

It's still worth checking for steam leaks and I assume that you have a good smooth sliding surfaces so the cylinder can oscillate with minimum loss of steam leaks.

I quickly gave up with the recommended fuels and converted it use Methylated Sprits ( denatured alcohol in the US?) which burns more cleanly. The steam plant has been used in a couple of other models with success, it can give you most of the pleasure of steam power without all of the expense,
Glynn Guest
Feb 04, 2020, 06:48 AM
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bboarder711's Avatar
Thread OP
Thanks Glynn,

Sadly most of my issue is with the steam plant itself and not the propeller shaft.

Any recommendations on amount of water to use and how long to boil to get a good head o steam?
Feb 04, 2020, 10:14 AM
Recreational Engineer
Tom Harper's Avatar
bb,

Sounds familiar, I had similar problems getting it to run. At best the system is marginal. So. here's what I did.

1. Disconnect the drive shaft for initial runs.

2. Use alcohol in the burner pan provided. I never got other fuels to work at all.

3. Get some cotton pads at the drug store and use one as a wick. They are about the same size as the pan.

4. Measure the capacity of the boiler and fill it to about 60%.

GlynnG's comments on the drive shaft are important. I'd clean the shaft and possibly polish it with fine grit paper and use a light coat of powdered graphite for lube. I also found that it was worthwhile to remove the engine and boiler from the boat and run it on the bench,

The boiler should come up to temperature in 5 minutes or so and provide a run of another 5 minutes. Others on this forum report better results, but that's what I have observed.

What problems did you see with the steam?
Feb 04, 2020, 12:06 PM
Registered User
bboarder711,
Just checked my Midwest Steam engine and it looks like I fill it with about twice the amount of water that you do (4 oz).

Watching your video again and two things occur to me. Firstly, it seems rather noisy, so do you oil the engine before running it?
Secondly, the short run with the engine speed winding down is something I'd expect when running out of steam, either the boiler running dry or the fuel burnt away.

Since you mention that this is after the fuel has been lit for 10 minutes, I'd be worried about you having an empty boiler. After filling the boiler up with hot water (I take a thermos flask of very hot water when sailing as it saves time and fuel) I'd expect to to have raised enough steam for sailing in 2-3 minutes. So, has your water boiled away in this 10 minutes and the engine is just running on a final gasp of steam and hot air?

Another point is that the propeller looks way too small. My engine runs without any load at around 2000 rpm and this is where you have to do the opposite to what electric motors require. For a good combination of duration and performance it is common to load electric motors so they are pulled down from the "no load" speed by something like 25%. Do this with a model steam engine and it would probably just have mediocre power and waste a lot of steam. I've usually aimed to run a steam engine under load in a model at around 25% of the "no load" speed (i.e. pulled down by 75%).

Just had another thought, small oscillators, like this Midwest engine, do take some time for the sliding surfaces to "bed in" and become smooth and reasonably steam-tight (but never totally steam-tight!). Once they achieve this the engine will turn over with silky smoothness.

Glynn Guest
Feb 04, 2020, 04:42 PM
Registered User
bboarder711's Avatar
Thread OP
Thanks all great stuff to go from.

looks like i need more warm water to start from. Ill trysome more with the sterno but the denatured alcohol will be easy with a few cotton swaps (I'll steal them from my wife)

ill try a shorter boil time and keep running the engine to break it in.

I do oil it but I know its not right. Also that is the pro that came with the kit. I will take it off for my next few runs.

Thanks again. Ill report back soon.
Feb 10, 2020, 06:38 AM
Registered User
sounds to me like you do not have enough steam in the boiler to keep the engine going. Maybe you have the boiler overfilled? I put 50ml of water in my boiler and I use either denatured alcohol or bio ethanol as the fuel with a wick material in the pan. boiler heats in about 5 minutes and i will get a good 20 minute run in the water. after the run is over there is about 10 ml of water remaining in the boiler.
Feb 11, 2020, 12:49 PM
User Registered
gen3v8's Avatar
60ml of water. Gel fire starter for fuel. Runs (strongly I Think) for 15 mins. Both have displacement oilers, a must.
Here`s Two playing
Midwest Fantail racing steamers (3 min 24 sec)
Last edited by gen3v8; Feb 13, 2020 at 02:26 AM.
Feb 12, 2020, 08:11 AM
Recreational Engineer
Tom Harper's Avatar
Impressive - are you using the stock burner pan and a wick?
Feb 12, 2020, 10:17 AM
User Registered
gen3v8's Avatar
Quote:
Originally Posted by Tom Harper
Impressive - are you using the stock burner pan and a wick?
Another pan that sits in the stock pan. It gets filled like a soft serve ice cream with a hydrocarbon? fire starter. Starts burning slowly at the peak and turns into a raging fire. I can go into a lot more detail if the OP does not mind
Last edited by gen3v8; Feb 12, 2020 at 06:42 PM. Reason: pics
Feb 12, 2020, 08:48 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
It's probably appropriate to go into detail...the OP labeled this thread 'Help' . If this was as a 'build' thread, then your concern is more polite...

I would like to see more, also...

Joe
Feb 26, 2020, 04:26 PM
User Registered
gen3v8's Avatar
Poor little boat getting punished. Well until it blew its silicon steam line joint off

Steam Midwest Fantail pulls skier (0 min 48 sec)


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