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Member postings for Mark Smith 3

Here is a list of all the postings Mark Smith 3 has made in our forums. Click on a thread name to jump to the thread.

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Thread: Hot air and stirling engines
28/05/2010 22:21:44
Sounds serious, Ian. I have overheated mine too, and it refuses to run now; as you say I have probably fried the seal. I might make a new one today and try again. The bell crank and rocker does work well and just need better engineering to improve it.
Mark
16/05/2010 20:03:45
The frame is aluminium so no problem there. You have already made a copy of those articles, Ian, I have them here. That is if you are talking about the 35cc rider. My engine ran for two hours then suddenlt stoped I think it probably overheated and changed the piston seal, but at least I know it  is a runner.
Mark
15/05/2010 22:15:32
Here it is, in the raw complete with wet undies. The mechanism is a bit hard to explain without pictures in case someone wants to try this crank drive for themselves.
The main advantage is the very low side loads on the con rods.
As you can see the bell crank was originally a Ross yoke for a Rider type engine but for various unknown reasons not to do with the crank it refused to run so I went back to the Beta design and changed it to what you see, and it works.
 

Edited By Mark Smith 3 on 15/05/2010 22:17:13

Edited By Mark Smith 3 on 15/05/2010 22:20:06

15/05/2010 21:51:31
Well, it's going again, and all I did on reassembly was change the oil to light sewing machine oil; a little heat and wrapped the wet undies for a cooler and away she went. This type of crank, namely a bell crank and a rocker arm give near perfect staight lines to the piston and displacer and not too difficult to build. Now to build the heater, cooler and the engine mounting.
Incidently I put two hard drive magnets that are kidney shaped on the flywheel for balance. I found the best setting was not `absolutely opposite the crank pin but a few degree ahead of it. I will post a pic of it at this stage but remember I am not an engineer and my engines are made of mostly found materials and junk parts, Ala rizzo.
Mark
09/05/2010 20:01:44
That's a good result for such a small motor, It's going to be interesting to see how it performs with a bit of pressure.
I've got mine in bits again, It was running well except the bearing on the yoke which came from a line trimmer gudgen pin caused it to wobble under load so I changed it and guess what, no go. Never mind just had to push on and find the cause.
Mark
30/04/2010 14:30:17
How do you explain that? What changed? By just using the "dyna" type motor as a driver of another engine and then you uncoupled it and it started perfoming as never before.That's amazing.
It might have something to do with that peculiarity that these engine have of being difficult to get started but once they do start they generally get better and better.
Mark
29/04/2010 20:08:32
In Andy Ross's book Stirling Engines he describes a demonstration that the Phillips engineers used to do. They connected a small stirling to a motor generator and motored the stirling with the electric motor until liquid air  formed around the hot cylinder. Then they disconnected the power unit and the motor ran the opposite way until the temperature equalised. Next they again coupled up the motor and  drove the engine in the opposite direction to normal until the hot end glowed red; from there under it' own power, the engine behaved as a stirling until it cooled. Interesting that you drove one stirling with another.
Mark
Thread: Why build a Stirling Engine?
14/04/2010 08:49:24
All very well, but the shortcomings of the Stirling engine will not stop people building them. I'm sure some very knowledgeable person could tell us all the shortcomings of the steam engine and its boiler, most engineers have some idea of what they are but many thousands have built them just the same. I think the point is being missed that model engineering is supposed to be an enjoyable hobby that anyone can enjoy. Of course there are problems with hot-air engines but that knowledge does nothing to diminish the joy of seeing something one has built spring into life, even if it has no practical application. It should be remembered, too, that some of the best hobby engineers have been fascinated by this engine and built some beautiful examples.There might be many reasons for not building a hot-air engine but, unless you are a believer, you might just miss the many reasons to build one.
Mark
Thread: Hot air and stirling engines
12/04/2010 06:41:06
Glad your day was good,  Ian. I am going to use the system Roy Darlington uses for cooler jackets, namely a tube slightly bigger in dia. than the cylinder and sealed at each end with O rings. I have a suitable tube, just need to get a box of O rings to find a suitable size that seals and is reasonably easy to assemble. 
Did you get my emails?
10/04/2010 08:33:22
I have a cheap chinese set of taps and one of them is a taper tap that fits the pressure guage I happen to have just need ptfe tape to seal. Emails working fine now.
Mark

Edited By Mark Smith 3 on 10/04/2010 08:34:14

09/04/2010 20:38:52
Ian, I think the best place for the snifter valve is the top of one of the pistons to ensure quick delivery of pressure from the crankcase to the working cylinders, otherwise the engine will probably stop when you apply any pressure. That may be why your engine slowed down when you fitted the side plate as the piston is now compressing below it like a two stroke.
Can you PM me and print your email address so I can check it against what I have here.
Mark
Thread: Musgrove engine Great Northern Steam Museum
06/04/2010 20:08:41
There is a good article about this engine on wikipaedia just google musgrove engine.
Mark
Thread: Hot air and stirling engines
06/04/2010 06:07:55
Could be this sunday Ian I'll ring. Still can't get your email to work otherwise I'd Chit Chat there instead of on the forum, which I doubt is its purpose; perhaps a general chat thread might be an idea??? By the way my first successful engine was cooled with the wifes underwear seemed to work a treat until I put a waterjacket on it; then I gave them back to her
Mark

Edited By Mark Smith 3 on 06/04/2010 06:11:22

05/04/2010 04:46:01
I finally got the Ross yoke engine to go. But not as a complete ross yoke. I combined the cylinder from my pressurised engine to half of the Ross yoke. I made a new rocker arm that extends to the same level as the the upper arm of the Ross yoke to  drive the displacer, ignoring the bottom half. The engine is now a Beta design and runs well on meths and three times as fast on gas. I think that as an alpha or rider engine the capacity of the cylinders was too small to drive that size of yoke. The engine as it is now is 3cm bore and  two cm stroke. Just have to make a proper cooler and heater instead of a pair of wet underwear wrapped around the cylinder and a simple meths burner for the hot end.
When I make some better looking parts I will post some pics.
Mark

Edited By Mark Smith 3 on 05/04/2010 04:49:36

03/04/2010 20:51:01
Which motor did you drive that with sounds impressive.
My ross yoke engine still refuses to run I am thinking now that the bore and stroke or capacity are too small for the size of the yoke whch is the same size as Andy Ross's 35cc engine. Maybe not enough power to throw the thing over on the compression stroke. I am thinking of bringing it out to your place to see if you spot something I might have missed,
Just looking at the ross yoke engines in  Roy Darlington's  book they are tiny compared to the engine capacity, mine is the other way round.
Mark
Thread: cylinder for hot air engine
25/03/2010 18:11:05
you'll probably find that the cause of the cracks is where the tube was welded in the first place. I salvaged some tube from an old chrome-molly bike frame, it didn't need turning down as it was very thin to start with. Also different parts of the frame were a displacer fit.
Mark
Thread: Hot air and stirling engines
16/03/2010 08:15:11
How is your engine coming along, Ian has it got more power now? Revs?  I have gone back to my pressurised engine and have started to install a bell crank in the bottom of the crankcase. Just have to decide what pins and bearings to use and work out the conrod lengths.
The young fellow I was telling you about has been talked out of his hot air project by his teacher who said it was too ambitious at this point, probably quite right as he  won't make very much of it. His interest has, however, been ignited so to speak.
Mark

Edited By Mark Smith 3 on 16/03/2010 08:17:20

25/02/2010 07:32:15
That is good news, Ian. I wish I could say the same so I have parked it for a while to think about. Meantime getting on with other engine projects. I still can;t reply to your emails as it just gets tossed back address wrong, odd that
Mark
19/02/2010 06:01:48
Hi Gordon, I'm not sure about your intuition, but I think the idea is to keep the power piston as cool as possible so the transfer tube needs to be as far, as the design allows, from the hot end. If you place the tube at the hot end  then the air is heated twice: incoming and outgoing plus the extra dead space involved.
A young man of my aquaintance is going to university next year and entering the Engineering dept of Canterbury University (the one that developed the Whispergen stirling engine). He has asked me to help him build an engine for his entrance project, a task I am happy to oblige him with. I have CAD drawings of the Devon as seen in my album -  which was successful. I will get him to make as many of the parts as he can. I think this is great and he should get every bit of assistance and encouragement as I can give him. You never know what someone like him could achieve in the future. 
Mark

Edited By Mark Smith 3 on 19/02/2010 06:11:25

19/02/2010 05:55:42
Thanks David, all good.
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