Build starting on a steam racer.

See cars and bikes being built for the salt

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David Leikvold
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why? why not!

Post by David Leikvold » Sat Feb 13, 2010 12:24 am

People just can't seem to help themselves, every overpowered crazy thing on YouTube started life as a sprint kart. I've seen them with big bike motors, little jets, lots of solid fuel rockets (tuppeny bungers!) a hydrogen peroxide rocket (I think Roscoe did that too) and even water jets. Funnily enough they never seem to handle well when they get out of shape at speed, which they seem to do quite frequently. One guy had 24 solid fuel rockets spread all over the back of his kart, it changed lanes on a public road (!) when some rockets burnt harder than others! What could possibly go wrong?? :shock:

Reece, if your radial steam engine is only going to be about 150 wide why not have a pair of them on a common crankshaft? Or maybe three of them. Never forget; some is good, more is better and too much is just right!
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ReeceJames
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Post by ReeceJames » Sat Feb 13, 2010 7:35 am

Don't get me wrong, I'd love to add more cylinders/expansion room in the engine itself. Where you run into issues is the production of enough steam to feed the engine. The engine may only be 150mm across but the steam generator powering that is the size of a coffee table.

The Pom's car suffered from that exact problem. Their multi tube steam generator (other than conceptually flawed I'll get to in a minute) could not produce enough steam to feed the turbine. Subsequently half the car was steam generator the rest was turbine and transmission. To get it up to the speeds to break the record, they had to run the boiler hotter and keep it cool with dry ice.

I'm taking a different approach. Copper monotube boiler with, depending on how it runs normally, a computer controlled super heater on each steam pipe to the pistons. Copper, unlike stainless, is easy to work with, stores heat well, goes to the temperatures and pressures required and in the event of a disaster, will not shatter. (Copper pipe just folds open and releases pressure, it don't explode into many pieces) Monotube boilers are also simpler to produce and their operation is quite simple. The old put put boats are an example of a monotube boiler.

Multitube boilers, especially out of stainless, are generally larger, more complex and prone to failure due to the convection currents that can cause superheating in parts of the assembly.
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David Leikvold
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what?

Post by David Leikvold » Sat Feb 13, 2010 4:40 pm

That whizzing sound you hear is what you said flying past my head without even slowing down. I really think it's time I did a bit of study on steam engines, especially mono tubes. You have to beat those Pommies :wink: !
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ReeceJames
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Post by ReeceJames » Sat Feb 13, 2010 9:11 pm

Sorry! I'll try and explain a bit below, but I doubt it's much better.

You have a couple of different methods of producing steam in a car, these can be loosely summarised as one of the following;

Fire Tube
Boiler - The traditional boiler used in locomotives, powerplants and the Stanley Steamer.
Water Tube
Mono-tube Steam Generator - Putt Putt boats and most importantly the Doble Steam Cars.
Multi-tube Steam Generator - Maritime boilers and a couple of failed steam locomotives.

All have their pros and cons.
Fire tube boilers take a long time to boil the water and get up steam. (Even my little 5" Blowfly takes 20 minutes to get a head of steam.) They also are the most efficient and are generally pretty safe if designed correctly. Firetube boilers require certification as they are pressure vessels.

Mono-tube Steam Generators consist of a single tube where water enters at one end under pressure, is heated and exits the other end as steam. The drawback is an efficient pump is required to supply water to the generator at all times. In the past these were self-regulating with complex mechanical systems, a small microprocessor will do as good a job and is cheaper. Monotube generators are the safest systems. In the event of a failure, they are not a pressure vessel and do not have the stored energy to explode. Construction of an effective monotube boiler has been elusive. However, 100 years has passed and the materials are better, hydraulics have been developed and we have computerised control.

Multi-tube Steam Generators operate on a similar principal as the monotube, except that the tubes are connected in parallel. This parallel configuration assists in construction as well as operation as the designs can be more elaborate. However, multitube generator suffer from a unique problem, if poorly designed, convection currents between tubes can cause superheated portions of the generator leading to an untimely failure.

Steam engine design hasn't changed much, but that's an explanation for another day. :wink:
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Post by Rob » Sun Feb 14, 2010 10:11 am

G'day Reece,

There's no penalty for a longer wheelbase and it'll improve stability. Same goes for weight, the difference will be minimal to your end result.

I'm guessing you have it covered but...remember to well baffle your water tank(s).

Cheers,
Rob
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ReeceJames
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Post by ReeceJames » Sun Feb 14, 2010 11:57 am

Rob wrote:I'm guessing you have it covered but...remember to well baffle your water tank(s).


Thank you Rob for the pickup!! I had completely forgotten about watertank baffles! (My train has a tall tank instead of a long one so doesn't suffer from the problem)
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Post by Rob » Sun Feb 14, 2010 12:05 pm

Glad it helped Reece,

Maybe a smaller sump at the rear of the tank with the pickup/outlet in there.

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Rob
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no room at the inn

Post by David Leikvold » Sun Feb 14, 2010 12:29 pm

Rob, I love wheelbase too but Reece only has a very small build area and has no room to build a long car. That's a real shame. Maybe design and build a long narrow car in two pieces and bolt it together when it's ready. That would also save building and storing a very long trailer too, so if it's done properly, it isn't as silly as it might first seem.

Reece, have you given any thought to a transmission yet? After my recent post about karts I was thinking about them again, they used to be all direct drive push start with the smarter guys building little trolleys to get the kart up to running pace before the back axle was dropped onto the bitumen. This made them a bit easier to start. If it would be better to run direct drive maybe you could consider a variation on that technique. Perhaps you could build some kind of arrangement like the motorcycle streamliners use, where an extra pair of retractable wheels keep the bike stable until it reaches a safe speed. You could use that to get the already driving back wheels off the ground an inch or so until a push car can get the steam car up to whatever speed you know it can pull away from and then retract those extra wheels to lower the back axle onto the salt.

Alternatively, if the steam engine has a reasonably narrow rev range and bags of torque down low perhaps a 5 or 6 speed big engined motorcycle gearbox might be handy especially with your preferred chain drive. If the bike motor was dead you surely wouldn't pay much for one from a wrecker and then you could remove all the unneeded engine bits including the crankcase and the primary drive gears, use the bike clutch (reinforced as or if necessary) and then everything else I've mentioned in the previous paragraph no longer applies. It could drive itself away from a standing start. Just more food for thought and discussion.
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ReeceJames
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Post by ReeceJames » Sun Feb 14, 2010 12:45 pm

Hey David,

The bolt together also assists with working on it, I can build the entire rear end then just bolt it in place. Certainly makes it cheaper to build and test initially.

With regards to the transmission, a bit more theory on steam engine operation. :)

Steam engines, unlike turbines and the Otto cycle have all of their power from 0rpm. The faster they spin, the more steam they use, the less torque they have. (Also the more force against them, the more torque is delivered up to the pressure of the system) With this in mind, a very high gearing ie 2:1 and maybe as high as 2.5:1 on normal tyres at 1000 rpm should see me up around the 240km/h. 1000rpm is fast for a steam engine, but in an oil bath, on bearings and the rotary nature, it should not present any problems.

This also makes the problem two fold. If the steam generator is not producing enough steam, the engine is starved and can't produce all of its torque. The opposite is also true, too much steam (not normally the case) and the engine is revving too fast and a gearbox becomes a requirement. It means the engine could have a larger capacity, run slower and get more torque as the steam system is keeping up.

So it's an interesting problem! I'm designing the engine to handle 1000rpm without an issue, and the steam system to keep up at that speed. Too much steam is better than not enough! If I get stuck, the gear ratio could always be upped as far as 3:1 depending on the run up.

For reference, no matter what happens, I won't need a push car! :)
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David Leikvold
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baffled

Post by David Leikvold » Sun Feb 14, 2010 12:51 pm

Reece, the water tank could easily be baffled by filling it with car wash sponges or a sized hunk of foam from Clark Rubber or even vertically mounted pieces of PVC plumbing pipe in whatever diameter you like. Both ideas are cheaper than aluminium and both would do the job. I used to run proper fuel tank foam in my sprint kart tank and the fuel never sloshed around and would pick up until it was bone dry.
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choof, choof, choof

Post by David Leikvold » Sun Feb 14, 2010 1:13 pm

1,000 rpm at world record pace? Sounds fabulous! At 240km/h that works out to only one turn of the engine every four metres. The car would be virtually silent from any distance. This thing is getting really intriguing :) !
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ReeceJames
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Post by ReeceJames » Sun Feb 14, 2010 1:49 pm

Baffles are fine, I won't need much water. 20L or so I believe is my guess. (Haven't got any data other than talking to a few people)

I believe the Doble steam motor revved out at 750rpm and was clocked above 100mph. I'm looking at a similar displacement in my engine, but not designing the engine to last over 100 years. (and counting)

Some footage of steam cars as they drove out of Jervis Bay. They were doing about 90km/h restricted by the older one infront. The two Dobles were just cruising.

My first test a while back. The next test is in the car. (Building a better prototype is on par with the cost of building a fully operational system)
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Re: Build starting on a steam racer.

Post by Rob » Wed Dec 12, 2012 2:18 pm

Any progress on this Reece? I just heard frokm the US that George Poteet is looking at a steam car for his next project.

Cheers,
Rob
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