Forum sponsored by:

Hot air and stirling engines

Search for: in Thread Title in

Mark Smith 3	07/07/2009 09:00:16
175 forum posts 36 photos	I am interested in hot air and stirling engines of which I have built a couple (that work). I would like to read articles by Andy Ross in magazines from the past. How do I access such articles? Edited By Mark Smith 3 on 07/07/2009 09:01:28
Ian S C	08/07/2009 14:38:51
7468 forum posts 230 photos	Hi Mark,I can't help with the Andy Ross articles,but its good to see a fellow stirling engine builder.I'v built about a dozen of various types,none of them pressurised yet.I'll put pictures up when I work out how to do it.My books are two of James G. Rizzo's,I'd like to get his second hard cover book. Ian.S.C
Geoff Theasby	08/07/2009 15:22:23
615 forum posts 21 photos	I built two Stirling engines, one from scratch and one from a pre-machined kit. Neither works! The kit one runs a little longer when fired up, as opposed to being spun with a finger, but I can't work out where the problem is. Regards Geoff
Mark Smith 3	09/07/2009 10:15:12
175 forum posts 36 photos	Thanks for your replies guys. I have James Rizzo's book as well as James senft. There is also a very good book by Roy Darlington and Keith Strong, Stirling and Hot Air Engines (designing and building experimental models). ISBN 978-1-86126-688-0. This an exellent book with many high quality photographs. The text is well presented and easy to read. I would love to get my hands on Andy Ross's book Making Model Stirling Engines, but the price at Amazon for a second hand copy is $800 US! That's about $1300 nz dollars. Geoff, I built several engines before I got one to work. It is very important there are no leaks in the working or power cylinders as even a pin hole will allow the gas to exhaust; though, strangely, some leakage past the piston can be tolerated as the model engines seem to run above and below atmospheric pressure. What air that sneaks passed, sneaks back on the so called compression stroke. Also, as you know, friction is the second biggest killer. I use bearing sets from old hard drives in all the linkages and that helps a lot, Some hard drives have quite big needle bearings that are good for the main shaft. Hope this helps Mark Edited By Mark Smith 3 on 09/07/2009 10:17:13
Ian S C	09/07/2009 15:58:53
7468 forum posts 230 photos	Hi Geoff,if you take your time you'll get them going,get rid of friction and air leaks.you may need to run them in by driving with an electric motor for an hour or two.Check that the displacer does't leak,submerge it in hot water and look for bubbles.This does'nt work on my engines as I make mine with a tube for the shaft,I just put mine in water and feed in air from my compressor. Hey Mark that price for Andy Ross's book is a little steep!I take it you are a Kiwi too,I live in Darfield Canterbury.I too use ball races from computor drives,I used to use ones from the hobby shop for RC cars.
Geoff Theasby	10/07/2009 14:06:43
615 forum posts 21 photos	Thanks for the suggestions about Stirling engines. I will try running the kit built one for a while from one of my Stuart engines running on air from my compressor. That should look suitably Heath Robinson! Regards Geoff
Ian S C	11/07/2009 11:12:52
7468 forum posts 230 photos	Geoff that sounds spot on,maybe it will work as a refrigerator instead,that would be ok.It some times helps if you run it in without compression,you'l use less air from the compressor.
Clive1958	12/07/2009 13:05:37
10 forum posts	Hi folks, its great to see people with an interest in stirling engines, I myself have only built two from kits, a low temperature differential and a thermal lag (both working), I have both James G. Rizzo's books, Roy Darlington and Keith Strongs, stirling and hot air engines and an Andy Ross book called stirling cycle engines which is very good (and only cost 50p at a steam fair), so as you can see ive read a fair bit. Anyway, carry on building and reporting, I am just about to build my own from scratch and hopefully will report the progress as time permits, incidently with regard to minimising dead space, has anyone considered putting the power piston below the displacer piston and filling the power cylinder and dead space with a thin oil which would be virtually non compressible, any comments welcome. Regards Clive
Clive1958	12/07/2009 13:05:55
10 forum posts	sorry folks posted it twice Edited By Clive1958 on 12/07/2009 13:07:37 Edited By Clive1958 on 12/07/2009 13:08:55
Ian S C	12/07/2009 13:53:01
7468 forum posts 230 photos	Clive 1958,how do you propose to keep oil out of the displacer?If your running the diplacer and power piston in the same cylinder ie beta type there should only be perhaps 1mm between the piston and the displacer.Even a gama or V engine doesn't have much dead space in the tube from the displacer to the power cylinder,you'd be better looking at regeneration,and pressurisation.See James Rizzo's "Tuba"or"Prova II",I think there are others in his 2nd hard covered book(I'v only got the 1st one and the paper back),you need to keep oil away!You can always use a diaphragm,and do without a solid piston,there was a bit about this in Model Engineer a few years back.
Clive1958	13/07/2009 11:33:36
10 forum posts	Ian S C, I was thinking of a Gamma engine with the power cylinder below the displacer and partially filling the power cylinder with oil, although if it ran at any great speed, the oil would probably get thrown into the displacer cylinder so maybe not one of my better ideas. Another (probably stupid) idea I had was to use a s/steel displacer cylinder with a lightweight steel displacer/regenerator moved by a magnet driven by the flywheel, along with a diaphragm power cylinder this would allow a totally sealed engine and no friction due to piston rods, although there would be some drag between the displacer and cylinder, I realise I could get similar conditions with a marble engine but was wondering if this might give greater speed althought i'm not sure how the displacer would react at higher speeds, any thought's?
Ian S C	13/07/2009 15:25:39
7468 forum posts 230 photos	Clive,not sure how you'd get rid of friction,I think some of the very early engines had little wheels on the displacer!You'd have to keep the magnet away from too much heat,possibly a guide at the cold end(could be brass or ally and sealed).I'v got 2 engines of the Ringbom type similar toJ.R.Senft's Tapper,they work ok although not over powerful,but they show that you don't have to connect the displacer to the crankshaft.Also got a free piston engine,so you don't even need a crankshaft!The piston on that one has a large magnet(came from the magntron of a dead microwave oven)on the bottom end this moves inside a coil and generates a small voltage-2-3volts ac,I don't know if this sort of thing could be reversed,maybe the magnet replaced with an iron core and a current to the coil,a switch could be opperated by the piston.The piston and displacer rest on springs,these replace the action of the flywheel of a normal engine.oops the coil and iron core would have to be attached to the displacer,could work but you would need a power supply. Edited By Ian S C on 13/07/2009 15:31:09
Clive1958	14/07/2009 12:15:50
10 forum posts	Ian S C, thanks for your reply, it has given me a few things to think about, I think my first engine will be either a Beta or Gamma and will be built as a test bed for experimenting, I intend to try pressurisation, regeneration and diaphragm pistons, although i dont think i'll use pressurisation and a diaphragm on the same engine. Clive
Ian S C	14/07/2009 14:39:09
7468 forum posts 230 photos	Clive,start with a simple V engine get it going well,my first one was a little V water cooled engine,when ok.Its now rebuilt as the smaller of my 2 versions of Tapper.Please could you tell me what the piston in your LTD motor is made of,if its carbon I don't know if I can get it although there is an outfit in Christchurch that makes brushes for electric motors so I could try them.
Clive1958	14/07/2009 19:46:22
10 forum posts	Ian, The piston on my ltd is a plastic diaphragm, have you thought about the carbon rods used for carbon arc welding, or possibly the ferrite rod used in old radio tuners, other than that motor brushes should work fine. Clive
Mark Smith 3	15/07/2009 11:33:35
175 forum posts 36 photos	Hello Ian, yes I am a kiwi and I live in Christchurch. My email address is [email protected] if you feel like getting in touch. Clive has some good ideas that seem to filter through my mind as well. The idea of using oil to reduce dead space is probably doomed to failure because oil would carbonise and fill up the gap between the displacer and its cylinder not to mention what it would do to any regenerator in place. Water, however, is a possibility as described by Graham Walker in his very comprehensive book on stirling engines. Some water, like the oil, will find its way to the hot end as vapour and act as a two component compound fluid that has the potential to be more efficient at absorbing heat and rejecting it. The water also acts as a lubricant and helps seal the piston from passing air. The idea of using magnets to drive the displacer ,too, has merit but there is a danger that the displacer could go out of phase as the engine reaches higher revs. Someone will have to try it out. I am working on a design that uses a diaphram made of leather and rubber combo(stroke 2cm). The displacer cylinder and power cylinder are at 90degrees to each other and the displacer is driven from a rod that passes down the centre of the diaphram connecting rod which in turn passes through a gimbled yoke. The crank angle moves the displacer in the correct phase. This allows for a sealed system as the displacer rod is contained within the pressure space of the engine and nothing is open to the atmosphere. This is a little hard to describe without diagrams but I will let you know how well it works, if it works. We are full of ideas aren't we. Mark
Ian S C	15/07/2009 11:43:43
7468 forum posts 230 photos	The carbon rods for carbon arc welding are only about 8-10mm dia,ferrite rods are not carbon.A diaphragm sounds a good 2nd choice.Started cutting metal for the motor just before tea time tonight,changed my mind,too cold!Do it tomorrow(why do today what you can put off until tomorrow),i'mcutting the bottom out of a large frying-pan,13"dia.I'v got two of them,one for top other for bottom.I'v got some 6" plastic pipe,foam for displacer,6"diax3/8" perspex disc for the flywheel,plenty of small ball races.I,ll just have to work out the power piston/diaphragm. Thanks for the info.Ian.s.c..ps you'v proberbly noticed I'm a bit of a night owl.
Mark Smith 3	15/07/2009 12:07:21
175 forum posts 36 photos	Ian to upload photos just go to my photos in the left column and create an album. Mark
Ian S C	15/07/2009 12:24:24
7468 forum posts 230 photos	Hi mark,motor looks good,should be reasonably powerful(hot air- mouse power),What is bore and stroke?
Mark Smith 3	15/07/2009 12:32:42
175 forum posts 36 photos	Hi Ian, Bore is 2cm Stroke is 2cm. Reasonable power on Meths much better with Gas. On gas it runs so fast I think something might break.

1 2 3 4 5 6 Next > Last >>

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts

*Oct 2023: FORUM MIGRATION TIMELINE*
05/10/2023 07:57:11
Making ER11 collet chuck
05/10/2023 07:56:24
What did you do today? 2023
05/10/2023 07:25:01
Orrery
05/10/2023 06:00:41
Wera hand-tools
05/10/2023 05:47:07
New member
05/10/2023 04:40:11
Problems with external pot on at1 vfd
05/10/2023 00:06:32
Drain plug
04/10/2023 23:36:17
digi phase converter for 10 machines.....
04/10/2023 23:13:48
Winter Storage Of Locomotives
04/10/2023 21:02:11
More Latest Posts...
View All Topics

Support Our Partners

Shopping Partners

Subscription Offer

Latest "For Sale" Ads

Reeves** - Rebuilt Royal Scot by Martin Evans
by John Broughton
£300.00
BRITANNIA 5" GAUGE James Perrier
by Jon Seabright 1
£2,500.00
Drill Grinder - for restoration
by Nigel Graham 2
£0.00
WARCO WM18 MILLING MACHINE
by Alex Chudley
£1,200.00
MYFORD SUPER 7 LATHE
by Alex Chudley
£2,000.00
More "For Sale" Ads...

Latest "Wanted" Ads

D1-3 backplate
by Michael Horley
Price Not Specified
fixed steady for a Colchester bantam mark1 800
by George Jervis
Price Not Specified
lbsc pansy
by JACK SIDEBOTHAM
Price Not Specified
Pratt Burnerd multifit chuck key.
by Tim Riome
Price Not Specified
BANDSAW BLADE WELDER
by HUGH
Price Not Specified
More "Wanted" Ads...

Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues