Hot air and stirling engines

[Ian S CParticipant @iansc]

Did the old lathe die in the earth quake, or did you just flog it off, it was a pretty depressing time, we just don't know how lucky we are out here on the plains.

The wee motor above was my last Stirling Engine completed, there is a Rhombic part built on the shelf while I fiddle around with a single cylinder open crank 4 stroke IC motor.

Ian S C

[Mark Smith 3Participant @marksmith3]

No I sold it as I had to go to smaller digs. Had no room for it. Still trying to upload photo can’t seem to find instructions. The motor above looks good.

[John OlsenParticipant @johnolsen79199]

Hi Guys, Those hub dynamos, and indeed most bicycle dynamos, are designed to not need a regulator. The way they do this is by sizing the winding to produce a maximum current that is equal to what is required by the load. If you run one open circuit, the voltage produced will be proportional to the rpm, and at higher speeds can get quite high. When the correct load is connected, the current taken by the load keeps the voltage reasonably within limits. Effectively the load is being supplied with a constant current, once the speed is high enough to work properly. One difficulty with this scheme is that the resistance of the filaments increases as they get hotter, so the voltage does tend to rise with rpm.

One thing this leads to on bikes is a tendency to blow both bulbs at once…if the headlight goes,or comes loose, all the current will go through the tail lamp, which will not survive.

If you want better regulation, the simplest way is to rectify the AC and connect a suitable battery. A bike dynamo is usually rated for about 0.5 Amps if I recall correctly. so a motorcycle size of battery can probably absorb that sort of charge rate without needing any other regulator.

John

[Ian S CParticipant @iansc]

Hi John, I'v got an old Sturmy Archer hub dyno, I rigged it up to use on a wind turbine(live in Canterbury, nor west winds), I only got two types of wind, too much, and too little. I have run it from my Ross Yoke ALPHA motor.

As for regulation, I just load things up until the voltage stays stable at the rate that I want. But I'm going to go electronic and use a LM317K voltage regulator so that I can have an adjustable voltage supply. For most work I need a 12V supply for the fan on the radiator, and 6V for the radio.

Here is an alternator I built from an old 6 pole squirrel cage shaded pole motor that I replaced the armature with a permanent magnet one.

Ian S C

[Mark Smith 3Participant @marksmith3]

Hello, I’m back.

Sad to report that Ian S C has died. He will be missed.

I’m  still interested in stirling/hotair engines but I haven’t built one for a year or so, I’ve had some health issues recently but all good now.

As some of you will remember, I live in Chritchurch New Zealand. I am well retired but volunteer at Ferrymead Historic Park and belong to the Rural history Museum. I’m currently working on a Robinson hot air engine which I’ll  be running at the park Saturday night for our market night.

We get to repair all manner of farm machinery including hit and miss engines.

Mark Smith

[JasonBModerator @jasonb]

Sad to hear about Ian, I had noticed he had not been posting for some time.

If you have any queries about the Robinson then both Geoff from the Anson Engine museum and Graham Corry of Alyn foundry have  agood knowledge of these. Both can be found on teh “Alyn Foundry Models and Engines” Facebook page

I’m at the early stages of a scratch built 1/5th scale Denny Improoved Rider engine

[Mark Smith 3]

On Mark Smith 3 Said:

Hello, I’m back.

Sad to report that Ian S C has died. He will be missed.

I’m  still interested in stirling/hotair engines but I haven’t built one for a year or so, I’ve had some health issues recently but all good now.

As some of you will remember, I live in Chritchurch New Zealand. I am well retired but volunteer at Ferrymead Historic Park and belong to the Rural history Museum. I’m currently working on a Robinson hot air engine which I’ll  be running at the park Saturday night for our market night.

We get to repair all manner of farm machinery including hit and miss engines.

Mark Smith

Welcome back Mark

Sorry to hear Ian SC has died – he helped me with some Stirling problems when I was a total beginner, and I remember thinking it  marvellous that his advice came from the other side of the world!

Dave

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