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Hot air and stirling engines

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Gordon W18/02/2010 11:25:01
2011 forum posts
Hi all, back again. Finally got started on my engine, now the weather is only -4.
It's based on old designs, seperate power cyl. and hot cyl.
My intention is to make just about everything variable so I can play about and try different settings etc., including pressurisation, well up to 2 or 3 bar.
I have a couple of questions that some more experienced people may help with, - Where is the optimum position along the displacer to take the hot air to power piston? Most designs show it about midway, before cooling section, some show it in the cooling section, my (bad) intuition says should be in the hottest part.  I'm making diffuser bush and gland in a replacable piece ,any sugestions for gland matl. and design? Also am reading Reader and Hooper on Stirling Engines, very useful.  :24:57

Edited By David Clark 1 on 18/02/2010 18:25:51

Martin W18/02/2010 17:13:25
940 forum posts
30 photos
ED
 
Whats up with this thread, and some others??? I am having trouble with the posts going under the 'Ads' on the right hand side!!! This does not happen on all pages of this thread so I don't believe its my system. This page seems the worst so far, anybody else suffering from this on this thread???
 
Sorry to the contributors for straying off topic but it is annoying and needs sorting.
 
Cheers.
 
Martin W
Mark Smith 318/02/2010 18:00:41
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175 forum posts
36 photos
I see what you mean, that hasn't happened on this thread before but I  have seen it on others now and then.
Mark
Les Jones 118/02/2010 18:17:11
2292 forum posts
159 photos
Hi,
         I am having the same problem with the adverts. I have tried Firefox 3.6, IE8
and Google chrome 4.0.249.89 (Latest version I think) 
A temporary way round it is to copy and past the text to notepad etc. To copy put the cursor on the first character. Hold the left mouse button down then drag the cursor  to the end of the text. The text will now be highlighted. Now press the control key and the C key together. This copies the text to the clipboard. now got to notepad and press control and V together. The text will appear in notepad.
Les.
Martin W18/02/2010 19:14:11
940 forum posts
30 photos
I don't know whether somebody has done something but now the posts are OK and terminating before the 'ads' column.
 
ED done anything???
 
 
Martin W
David Clark 118/02/2010 19:56:23
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3357 forum posts
112 photos
10 articles
Hi There
Yes, sorted it out.
regards David
 
Mark Smith 319/02/2010 05:55:42
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175 forum posts
36 photos
Thanks David, all good.
Mark Smith 319/02/2010 06:01:48
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175 forum posts
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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

Ian S C19/02/2010 09:38:25
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7468 forum posts
230 photos
Hello Gordon, I agree with Mark The pressure transfer to the power cylinder should come of the cold end of the displacer cylinder. I have got a plan for aengine model that dates back to the 1930s that taps the pressure from midway down the displacer cylinder, I started building it when I first got into hot air engines, but stopped, and built a V type that ran for many years until pulled apart to make another engine. Mark give your friend my best wishes, and if any help required I'm here. Put some heat on the Ross Yoke engine tonight,but it needs freeing up quite a bit more. It should also get the cooling system hooked up. Ian S C
Gordon W19/02/2010 09:54:10
2011 forum posts
Thanks for all that, will put in 2 tappings, one at cold end, one just before water jacket. Had not realised until recently how much research is being done, its a good thing.
Ian S C19/02/2010 11:26:00
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7468 forum posts
230 photos
Gordon, I found the old artical, its in an old magazene called "Mechanics" incorporating English Mechanics &The World of Science, The Amature mechanic & work, And it was a 1944 edition. The interesting thing about the engine is that the displacer is just under half the length of the displacer cylinder, so that when the displacer is at the cold end, the transfer tube is open to the hot air going to the power piston.When the displacer is at the hot end the transfer tube is open to the cold end. Both piston and displacer have a stroke of 1 1/4",the displacer has a bore of 1" and the power piston is 3/4" dia, It has a 4 1/2" dia flywheel,and the cold end has a water cooling tank. Ian S C
Ian S C24/02/2010 09:28:09
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7468 forum posts
230 photos
It's a runner!! Got the Ross Yoke engine running today, its still a bit stiff so there is not much power yet, but I'v had it up to about 650rpm., it runs a bit rough but I think that when it gets up to 1000+ it should smooth out.Ian S C
Mark Smith 325/02/2010 07:32:15
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175 forum posts
36 photos
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
Ian S C25/02/2010 08:40:27
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7468 forum posts
230 photos
Mark, how heavy is your flywheel? I'm using the 6 1/2" flywheel off the engine I had at Homebush, to start with a bigger one wouldn't hurt, I think that once its run in a smaller one would do,but it does need the weight at first. I take it you got one the other day about a different type of engine. Back to my motor,I'v got to work out a pump system for the water cooling, the water jackets are too small and it won't circulate on its own. I may have to put some fins on the bottom end of the stainless hot tube. Ian S C
Ian S C11/03/2010 10:23:21
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7468 forum posts
230 photos
I was doing some work on my Ross yoke enginge today, and looking at the side rod on the yoke and thinking, now there is a place to drive a pump,either a water pump for cooling, or a compressor for pressurising the engine. Ian S C
Mark Smith 316/03/2010 08:15:11
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175 forum posts
36 photos
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

Ian S C16/03/2010 10:47:12
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7468 forum posts
230 photos
I'v got to give the motor a squirt of CRC every now and then, its still a bit tight. I,ll fit the radiator tomorrow, that'll help a bit. I'v got two sources of pins, chassis of VHS machines etc, and other electronic/electrical stuff that goes round, and needle roller bearings. I would tend to go ahead and help the young lad build a simple engine, perhaps James G.Rizzo's Dolly 1 or 2, or a little V type(only 1 crank needed), think his teacher is a bit of a pessermist. Even if he does'nt make it all he'll have the motor and value it for many years. Ian S C

Edited By Ian S C on 16/03/2010 10:51:04

Ian S C03/04/2010 09:59:15
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7468 forum posts
230 photos
Hi , I'v found quite a good motor to use as a generator, it came from a Braun stick blender, it's a 220v dc motor rated at 500w, the newer ones are 600w. This motor generates a good voltage even at low speeds, I was running it tonight at about 350rpm and 20volts. Ian S C
Mark Smith 303/04/2010 20:51:01
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175 forum posts
36 photos
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
Ian S C04/04/2010 03:49:01
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7468 forum posts
230 photos
Hi Mark, used the Ross Yoke motor, Its slowly comming up in power. I'm starting to prepare it for pressurization. Got to design a seal for the bearing. I want to make a fitting for a pressure gauge, and go to the local tire repare shop for a valve stem and valve, not a lot more than that, although I'll make a flywheel so it can have its own one. come on out , tomorrows good, tuesday on I hope to be busy building bale feeder machines (we'v got one on order, hope for more, mabe half a dozen). Ian S C
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