Steam Schwinn concept

[JemmaUK]

If you do a search on the Hudspith steam bicycle you will find a machine that is nicely built and professional - speed is fair and the bike is rideable when you are used to it...

The problem is range - namely that the machine uses a solex type setup with the motor on one side and the boiler and burners on the other over the front wheel.

Given the space that the standard cruiser frame has for fitting engines etc why not fit a custom boiler in that space? or better still mount a water tank along and above the top tube, with the boiler in the upper middle section and condenser towards the bottom of the space..

Then a twin cylinder engine acting on the pedal cranks (in such a way as the bike is still pedal-able) which means that you (in the case of a hub equipped bike) would have a 3/7/8 speed transmission - which could in the case of the shimano nexus 8 and automatic transmission controller give you a fairly fast machine..

If this machine was built and could provide just a small amount more power than me pedalling you could have a top speed of 18-20 mph with a fully variable transmission.

And the best bit.... with a petrol burner you are running on two easily obtainable commodities...

Any comments?

Jemma xx

 

[Bean Oil]

Any comments?

Comments other than, "You have a technically inquisitive and brilliant mind; full of curiosities"? lol.

Steam pressure breaches would be painful.

Other than that, the sheer simplicity of something like the "happy time" 2-cycle is a little more alluring to me fitted to a bicycle rather than a possibly complex system of reservoirs and piping.

Now, a steam-powered motorcycle, something a bit bigger, would be really cool. Steam power can deliver an almost-insane level of torque...

 

[DougC]

...Then a twin cylinder engine acting on the pedal cranks (in such a way as the bike is still pedal-able) which means that you (in the case of a hub equipped bike) would have a 3/7/8 speed transmission - which could in the case of the shimano nexus 8 and automatic transmission controller give you a fairly fast machine..

If this machine was built and could provide just a small amount more power than me pedalling you could have a top speed of 18-20 mph with a fully variable transmission...

...Any comments?

With "traditional" sliding-vane type steam engines...... a transmission is not necessary at all, because the steam engine generates its maximum torque at zero RPM's anyway. That's why on old trans, the pistons connecting rods are connected straight to the wheels. There is no transmission (-for a steam locomotive to reverse, the steam engine actually runs in reverse order-).

Of course for a bicycle use you'd want some way for the engine to "freewheel"; steam locomotives didn't have that. But the engine is going to deliver maximum torque all the time, so you wouldn't even want it running through a geared hub. The hub wouldn't last long.

Also (at least in the USA) if you want to burn a fuel to generate lots of relatively-low-level heat, propane is a better fuel bargain than gasoline is.
~

 

[JemmaUK]

The breach problem is part of the reason for the engine parts to be at the back, which means the feedlines and the overpressure valve for the boiler etc can be directed aft... hot metal up the bum often offends

As to the problem with the hub and the gearing - to get a reasonable speed it will have to be geared because I dont know of many steam engines either single or compound that have rpm figures of 8000+

There is a very easy way to prevent hub munchiness and that is close the regulator...let the bike over-run, change gear, open regulator (...scare patrol car).

Steam locomotives didnt bother with gearing for several reasons - the main of which was that the majority of lines were fairly flat and if you couldnt make a given hill you just slapped another 0-6-4 on the front and that was that.... the mallard was able to run up a figure of 126 because she was streamlined and brute force powered - the same figure could have been achieved by a smaller engine if it had been fitted with a transmission of some description - indeed some prototypes were...

Fuel - propane great but its a gas - pressurised - therefore heavy...

petrol - less energy - liquid - unpressurised - lighter and people have experience with it

parafin - icky - tends to go solid on you - hard to tell quality and apparently causes coking up in short order... add that its hard to find in decent qualities here at least...


so we would need

two tanks - fuel and water + aux tank for engine lubrication

fabbed boiler & condenser linked to water tank - pre heat water and condense stream - best use of heat energy

fabbed burner assembly and associated hardware

2 cylinder reciprocating steam engine horizontally mounted driving pedal cranks through eccentrics

regulator controls for steam/water/fuel to burner and cut off for latter

steam regulator could be a twist open affair located in such a way as the regulator can be closed - hub shifting accomplished - and then regulator re-opened

automatic boiler safety valve venting to rear with manual control

valve system with setting to enable cylinder venting to atmosphere (allows free pedalling)

relevant gauges and monitors - speed/boiler pressure/water level etc.


If the feed water when the machine is started is already boiling (kettle for example) this would shorten the steaming up time...

anything I missed?

It is true I do have quite a mechanical mind and often I dont think of the obvious - just one of my talents I guess

 

[Abeagle]

In some areas you might need a boiler operators license. lol
You find some of the most interest ideas, thanks for sharing them I really enjoy them.

 

[JemmaUK]

You could build one and then let us know how it works. Sound like you have it figured out. For fuel wood and coal is still plentyful.
Norman

The problem with a solid fuel system is feeding it and the size of the required firebox...

With a burner you have an area that acts sort of like a space heater plate - steaming up the boiler with a high energy production in a small space... but it requires a liquid fuel... trying to shovel in coal at 20mph on a pushbike is the easiest way to bury yourself in the side of an SUV (although the resulting boiler explosion would probably help cut CO2 emissions...)

My problem is that I have the brains but I dont have the money/tools/experience to make the things work *sigh*.... making up a boiler would require specialist tooling and expertise and yes, in the uk you would need a boiler safety check....

Additional to the above by the way would be some sort of flue for the boiler - I propose a reward facing horizontal affair somewhat like the twin exhausts on motorbikes - however with the tips angled in such a way as to enhance the 'draw' of the boiler using the vacuum created by passing air and feeding from the bottom back of the boiler to a point alongside the back wheel - venting away from the wheel of course.. running it from the lowest available point means greatest heat transfer.. and therefore better efficiency

Jemma xx

 

[Bean Oil]

With each power stroke, steam is expelled... meaning one may have to have a rather too-large a storage quantity of water on board making the rig a bit too heavy... not to mention the storage of fuel.

Although a steam-powered motored bike would certainly be a novelty even it it had a very short range.

Fascinating, yes; a fun project to build. One could spend months on the plumbing alone... and the end result could be beautiful but I'm afraid it's all a bit too complex to be contained within the confines of a rideable bicycle.

As interesting as this idea is, I also appreciate real simplicity which is why the 2-cycle is so elegant if not obnoxious (or, noxious... lol)

 

[Sianelle]

This is a really fascinating website on practical steam Jemma.

http://www.lynxsteamengines.com/converting.cfm

Basically they've figured out ways to convert IC engines to function as steam engines which is one way to get past the need to own a lathe and machine everything yourself.
Have a look at their designs for flash boilers too. Which again is one way to get around all the heavy engineering and the need to have a machine shop.

 

[DougC]

...As to the problem with the hub and the gearing - to get a reasonable speed it will have to be geared because I dont know of many steam engines either single or compound that have rpm figures of 8000+ ...

I do not see why you need 8000 rpm's, unless you wanted to have a sort of drop-in replacement for a current mini engine.

As far as steam engines not needing transmissions--most steam locomotives never had them because they simply didn't need them. The maximum torque occurs at zero RPM, and decreases as the RPM's rise (because the boiler can never reach a higher pressure than when the RPM's is zero). For this reason, steam engines are most-efficient at lower RPM's and larger displacements; it would work better to change the displacement and drive system so that the engine spins equal to the rear wheel speed.

Steam engines in the past had long stroke:bore ratios up around 8:1 or more, which boosted their thermal efficiency. Most modern engines are square (bore~=stroke); the longest crosshead engines now still only have strokes 4X or 5X their bores. A hydraulic cylinder would seem to be a better starting point than converting an existing engine.

As far as what type of fuel to use goes,,,, since "knocking" isn't an issue and burnt fuel doesn't contaminate the drive system, a steam engine could use any fuel (or combination of fuels) that its fuel delivery system could handle.
~

 

[Sianelle]

A hydraulic cylinder would seem to be a better starting point than converting an existing engine.

The advantage of converting an existing engine lies in the fact that you don't need a well equipped machine shop to do it.