Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: Ken S. on September 24, 2018, 02:31:43 am
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Hello Group:
I just picked up a Stuart Sirius steam engine and was wondering about my options to install a reversing mechanism. I'm trying to get a layout set up.
Thanks for the thoughts.
Ken S.
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Welcome Ken...it will certainly be of benefit to read as much about the Stuart Sirius engines :o prior to any further work
Following is a somewhat lengthy paragraph from the Stuart home page....
"The Stuart Sirius was originally designed for racing steam hydroplanes. Particular attention was given to the valve gear and steam passage design with the result that the engine produces great power using a surprisingly low volume of steam. Our tests have shown that running at 2800 rpm the engine produces 1/3 bhp. at 80 psi"
https://www.stuartmodels.com/item/59/stuart-sirius-unmachined
The last sentence in the 2nd paragraph has me a little perplexed O0
Derek
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As far as I know it cant be fitted with reverse. To reverse it would require a change in valve timing and there is no way to do this without making it a permanent change. Ive worked on a few of these and timing is critical.
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That’s quite right, the Sirius engine can’t be reversed. Some piston valve engines can be reversed by swapping the intake and exhaust, but the engine doesn’t run nearly as well. I have an old Stuart MTB1 which has the same basic configuration as the Sirius (twin cylinder single acting with a piston valve) and I’ve just tried swapping the intake and exhaust and it doesn’t work.
In any case the Sirius will not always self start as there are only two power strokes per revolution, and even if it could be made to reverse, in a radio controlled boat, you could be left with a model out of reach and no power.
Derek, I think the 2nd para. means only castings and gears are included unlike most of the other Stuart kits that include other materials, nuts , bolts etc.
Malcolm
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I think My Modean engine goes faster in reverse, %% As can be seen going forward in this Months Model Boats Mag :}
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OK, so no direct reversing mechanism for the Sirius, didn't think so but wanted confirmation. Would a dog clutch type set-up be do-able?
Thanks for the welcome :-))
Ken
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Ken......there is an option of using a Kitchen Rudder......[this is actually a variable reverse thrust bucket].....I understand they were used in steam engined Naval Picket or Pinnace boats around the WW1 period
Malcolm's comment about non self starting may be an issue to be considered ......so from this, it would be doubtful that the Sirius engine would be suitable for the loading/unloading clutching arrangement, however naturally a radio controlled throttle to limit engine speed should not be discounted
The following is just the search beginning.....
http://www.youtube.com/watch?v=WE02jxgGknc
https://www.scribd.com/doc/22985018/Kitchen-Rudders-Their-Inventor-and-Some-Applications
Derek
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Interesting but I think I should elaborate a little more. I'm not intending on building a boat, even though I am soliciting info on a model boat forum. I am desperate to get the information I need from the experts out there, especially on the steam end, from you guys who respond. The basics I understand, boiler, engine (Sirius), water pump, condenser, throttle etc. but the drive train is perplexing me. I'm building a steam engine driven tank built around the Sirius. I think the dog clutch will work, maybe something based on the following design:
https://www.youtube.com/watch?v=TpQpAXu4wOg (https://www.youtube.com/watch?v=TpQpAXu4wOg)
[color=var(--ytd-video-primary-info-renderer-title-color, var(--yt-primary-text-color))]
Any suggestion on splitting the power to left and right sides tracks?
Ken S.[/color]
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Since the sirius rpm is so high you could use a centrifugal clutch like on model helicopters - cheap and simple
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Interesting on the heli centrifugal clutch.
Maybe you guys can help me on the basics:
Fuel supply Butane/Propane (gas tank)
Burner
Boiler
Water Supply Tank
Water Pump
Super heater
Throttle
Engine
Lubricator
Condensor
Drive Mechanism
Forward/Reverse
Left/Right
Questions right now are:
1) Can I skip the condenser and pipe the exhaust directly into the water supply tank? Pros/Cons?
2) Can a boiler change angles significantly (~30 degrees) and still operate with water sloshing about. Probably doesn't happen much on boats.
Thank you again. I may form the as a new topic, at least for the steam part as I proceed with the design and construction. Hopefully as I go along you'll enjoy building it with me. Thank you all again for your advice.
Ken
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[size=0px]Question 1. can the condenser be skipped & pipe the engine exhaust directly to the make up water tank?[/size]
[size=0px]No - the exhaust steam will be an emulsion of water + steam oil, this is why a de-oiler is used [not a condenser] the condensate will cool & [/size][size=0px]separate, however a small oil content remains. Oil [in any quantity] must not be injected into a boiler as it would result in the oil adhering to fire tube heating surfaces & hence progressively provide a surface that will reduce the transfer of heat to the water within the boiler [/size]
[size=0px]Question 2. can the boiler axis angle change to ~ 30 degrees?[/size]
[size=0px]A vertical boiler could be tilted to an off axis angle of ~~30 degrees & due to design still provide limited function, a horizontal boiler by design would not be capable of function at such angles [/size]
[size=0px]Derek[/size]
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Hi Ken,
How hard are you going to run the Sirius engine?
Most of the ones I have seen photos of are in Round the pole racing models and use liquid fuel (kerosene/paraffin and run flat out.
Gerald.