Hello HeadSmess,
It's always wonderful to see someone else who has a need for steam.
Your design sounds very interesting.
I can tell you about my bike now that I actually have it.
The engine on yours sounds like a double acting steeple engine with 4 inline cylinders
Could you tell me about what size cylinders it uses and rpms you plan to run at?
The engine on mine is a 2 cylinder single acting engine. It is not very efficient has probably around a 35% cutoff and because it's small 1x1 cylinders not efficient from thermodynamics perspective, but it's small, light makes power my estimate puts it at about 1hp @250psi at the shaft at around 3000rpms, but it weighs only 6 lbs.
It's a stuart sirius engine, but stuart no longer is making the casting although there are a few left, but it's not worth the money and time unless there was a specific reason fro this engine.
When I build my own bike I probably will try to use a converted gas engine and turn it into a single cylinder uniflow engine with a 5% cutoff and a bash valve. That will have better efficiency thermodynamically and use less steam. In a recent edition of the SACA magazine it described the design of uniflow exhaust including equations to make the proper sized holes.
Boiler:
The boiler on my bike is a flash type and is mounted behind the rider adjacent to the rear wheel. Flash is lighter and much faster to start. Mine runs off 1 lb propane tanks, and I want to upgrade it to a 4 lb tank. Propane is better in my opinion it's easier to buy, a gas at room temperature, and has inherent pressure. DO NOT PLAN ON AEROSOL SIZED CANS. I can guarantee you'll run out of fuel before you even get going. The 1 lb tanks on mine barely last more than 20 minutes and I'm always left to wonder whether if the fuel runs out or there's some other reason why it's not working because the thing chugs down fuel. The 4lb propane tank will probably get you close to 2 hrs due to its larger liquid to gas surface area in the tank. I forgot to mention my bike doesn't function under 50 degree Fahrenheit.
In the bike that I'll may build in the future I will use an atomizing burner with diesel or kerosene as the main fuel because the ease of refilling and increased fuel milage. I would pressurize the fuel with a had.
The boiler is amazing though. It's make out of an inner and outer set of coils of 1/8" pipe and it steams well. I have pressure within 10 seconds and full pressure in 1 minutes. What's your boiler design like? Why does it take 10 minutes to start?
As for a water pump my bike uses a ram type pump basically there's no piston head it's a rod which has a pivot near the bottom and that connects to an eccentric on the drive shaft and that's the only pump. I know that the other bike like mine existence has a Coles Power Models pump in addition to a mechanical water pump and that water would leak backwards through checks at pressures like 500psi it's understandable. I just push mine or pedal mine around and it works fine to pump water in.
At the moment I am having problems with my manual water bypass, which is a swaglok toggle switch. For the first time since I've had the bike, I couldn't get it to close so no water was getting to the boiler.
As far as pressures go with my bike it is designed to operate up to 350psi as a system because the engine would be in danger above that pressure. I like to run it 250 to 300 but I don't get much power to the wheel, but otherwise you lose the efficiency in producing steam.
Temperature peaks around 700 degrees @ around 800 degrees standard 1/8" pipe turns red hot that was a problem in the minibike's boiler it would run 500psi, 800 degrees and it would glow red and that has caused leaking problems for it apparently, but that boiler is a more complex version than the boiler on my bike, but roughly the same size and would produce 30-40lb/hr more I believe.
As far as heat safety goes all the hot components are behind the rider, which solves issues with burns for the most part and I put on insulation good to 1000 degrees.
For oiling I use steam cylinder oil mixed into the water with a dispersant and this is actually working well even with super heated steam. It's good for the boiler and engine and all the steel tubing because it keeps everything from rusting and I have had no problems with it the dispersant I use is SC Gunk. I am gonna get a heater to use as a condenser on the bike in the next week or two and I can use this to recycle the water, but more importantly the oil so I don't have to keep adding it.
Friction though is definitely a problem and I have given though to using an engine that would run at almost human like rpms, but it would be heavy. It would likely be a large 1/8" scale steam train engine just one cylinder peaking at around 100 rpms. Friction's always been a problem with the high speed engines and the faster it goes the louder it gets as well. The seals don't seem to last terribly long.
As far as extra weight goes for a condenser like I said for me anyways I can not only reuse water, but oil so if when I stop for water all I need is water instead of water and oil that's a bonus and to be fair the bike doesn't care about an extra 5-10lbs for a condenser. Plus I plan on redoing my whole water circuit adding automatics and I want to run the water intake tubing coming out of the tank back and forth across the back of the condenser to cool the condenser and act as a feed water heater. The minibike had it's condenser running sideways to the wind with a fan to draw air through, but it wasn't very successful plus the fan would break due to torsional vibration along with the centrifugal clutch it used. I plan to mount mine underneath the water tank mount so it points the grid into the wind and have the condenser exhaust through a check valve into the bottom of the tank so that if there is steam left coming out of the condenser it has one last chance to condense.
As far as performance on Water milage my bike only gets 5 miles to the gallon and I carry a gallon so adding an extra 8 lbs for a second gallon so I can go 10 doesn't make sense plus I would have to make a tank. I just use a 1 gallon coleman fuel tank as my water tank.
How are you planning to drive your bike?
My current bike uses a friction drive where a spindle sits on top of the rear wheel, but the spindle isn't knurled very well so like I said it just slips and eats the tire away.
In the bike I will build in the future I would use either chains or belts and possible a CVT or dog clutch. I would depend if I use a 25-50 cc gas engine conversion or another engine like my sirius that's high speed or I use a lower speed engine that has variable cutoff.
Why don't you think having gauges is a good idea. More information about what's going on inside you machine is better. My bike only has a steam pressure gauge, but I plan to add a water pump pressure gauge to determine if the bike is pumping into the boiler or is bypassing and a fuel pressure gauge to be able to determine if the tank is running low or is able to maintain the pressure required to operate.
If you don't have a steam pressure gauge you have no clue what pressure's in your boiler although that's why you plan the relief valve, my bike doesn't have one at the moment and the one that was picked out in the 70s to use is no longer available, but what if your relief valve is clogged . You are really relying on that to prevent over pressure. I currently only have a temperature based shutoff fire shut off and a manual water bypass. I want to add automatics which control how much water is going into the boiler based on temperature and pressure and use the manual to force water into the boiler if needed and have an automatic bypass which works off pressure differences in two chambers.
Well I guess that's enough light reading for now, if you have any questions about my bike feel free to ask and search Richard Smith Steam Bike on youtube to see 3 videos about my bike.
Sincerely,
Robert Hopkins
