Searching for design by George Punter in ME
|51 forum posts|
On YTube there are 2 Diesel Engine videos of model Diesel engines made by George Punter; a Lister single cylinder and a freelance 4 cylinder.
I believe he did a write-up ME at some time in the past. The videos were dated for the Lister in 2012 and the 4 cylinder scratchbuild in 2009.
Does any one have memories of these models, and even better, can tell me which magazine one or other was in or can lend me copies odr photocopies.
I want to build a 3 cylinder Diesel to power a model I am currently building, the full-size version of which was powered by a Ruston VQBN 54 bhp.
If anyone has any advice, other than 'dont bother' I would most appreciative.
1107 forum posts
Model Diesel engines are apparently quite difficult. I have never tried and offer no advice but *** Find Hansen *** has built plenty. His models are real works of art well worth a look.
2904 forum posts
Do you mean that 4-stroke diesels are difficult to make? The very simplest possible model engines to make are 2-stroke diesels.
For a 4-stroke, I expect the challenge of making a functioning injection system would be the critical issue. Camshaft operated injectors might be a vaguely achievable solution.
Edited By Muzzer on 13/01/2018 14:29:11
|349 forum posts|
This index should help you search for relevant articles in principal UK model engineering mags.
Lister single cylinder information on this site:
This Thread on this site may assist. Unfortunately Ennech hasn't been on-line here for some months.
Issues with drawings referred to here.
Hobbynuts build here. Hobbynut hasn't been on-line here for nearly two years.
Jasonb may be able to give you further information and 'leads'.
+ suggest that you search this site if you haven't already done so.
Apologies if you already know all this 'stuff'.
1107 forum posts
Yes, I was thinking of 4-stroke Diesel with injectors rather than the aero engine type. I assumed (probably incorrectly) that the Ruston engine refered to by the OP is a 4-stroke, it is definitely not like a mini aero engine!
Edited By Journeyman on 13/01/2018 14:51:00
|51 forum posts|
I should have provided a picture, this one from the Ruston-Bucyrus literature. This engine was developed around 1940 and was supplied for the war effort. For itrs primary application it was required to run at its rated speed 950rpm for a full working day, being started at clocking-on time, revved up to its working speed and kept there conmstantly unti kn=bocing-off time.
Reliabilty was the name of the game.
I have much of the currently available data about this workhorse but as some of you have remarked there are some difficult items to produce, especially the fuel delivery mechanism.
Thanks Phil for the ME Index. I will implement a search.
|51 forum posts|
Here is the picture -
|Neil Wyatt||14/01/2018 13:40:52|
18888 forum posts
To be pedantic, without a high-pressure injection system it's not a diesel although it may well be a compression ignition engine, whatever the RC flyboys call them
|51 forum posts|
Thanks for your interest, pedantic or not
My question has nothing whatsoever to do with model aircraft, radio controlled or otherwise. The power to weight ratio of these machines would probably preclude them from any form of flight.
If you have any knowledge of Ruston Diesels would you mind sharing it?
You will know of course that Rudolf Diesel was not the actual inventor of these engines which now are now known by his name. He should though be credited with considerable advances in the technology; his patent was 1897.. Barrton at Hornsbys built the first compression ignition engine in 1892, Akroyd held the patent. Hornsbys amalgamated with Rustons to become Ruston andHornsby Ltd. and the engine in which I am interested is one of a long line of very successful products.
Perhaps the matter of injection presure has always separated the generality of compression ignition engines from what you may be thinking of as a Diesel. Aren't desinitions always an object of debate?
Rustons always called them diesels and that's good enough for me.
|542 forum posts|
Akroyds engine was a hot bulb oil engine but I was told by a Hornsby trained fitter circa 1900 that a true diesel engine had been developed but the complexity and cost of retooling the factory was too great as they were selling lots of oil engines which could run on any oil that would go through the injector and any untrained labour could work them.The Statue Of Liberty used one to power the light.
|Mark Rand||14/01/2018 16:50:27|
|1123 forum posts|
haven't got any links other than Find Hansen, who is extremely reticent about sharing his techniques in any way other than selling his models.
As to arguments about what is a Diesel, there aren't any:- The Diesel cycle is constant pressure fuel injection and combustion as opposed to constant volume combustion. There again, modern engines merrily use constant pressure combustion for spark ignition engines. Bl**dy electronics. Bah Humbug!
21967 forum posts
I don't think the lister in George's video was running as a true diesel as he was using model aircraft fuel and got it going as a compression diesel.
Our forum member Johan Van Zantan has made a very good true diesel and I think the injector runs at something like 150bar, it was featured in ME a few years back
There are some more photos in his album
Edited By JasonB on 14/01/2018 17:43:34
2904 forum posts
Still not sure where these definitions are coming from. Is a "compression diesel" not a "true diesel"? I suspect when you talk of "true diesel" you simply mean "4-stroke" diesel. Of course, most marine diesels are actually 2-stroke. Apart from the lack of a camshaft, you might struggle to tell which they are externally.
|1054 forum posts|
Surely any internal combustion which uses the heat generated by the compression of air in the cylinder to ignite the fuel adheres to the diesel principle and is therefore a 'true diesel' engine ? Discuss
|John Olsen||14/01/2018 20:46:35|
|1223 forum posts|
There is a guy in Auckland NZ building a model of a three cylinder opposed piston Commer engine. Last time I saw him, making working injectors was pretty much the only remaining obstacle. They are not something that scales easily!
As far as definitions go, I would regard a Diesel as one that scavenges the cylinder with air, and injects the required amount of fuel after compression at the right moment to time the ignition. That covers both the two stroke and four stroke versions in full size. Some types may need a separate blower to scavenge them.
The model aircraft engines are compression ignition, but do not use fuel injection so are not actually a Diesel. Incidently the model type can be built in four stroke form, but generally this isn't done because you need a means of varying the compression to control the ignition timing, and this is hard to arrange with a four stroke head. (You use a small cylinder with an adjustable piston built into the head along with the valves, makes things a bit crowded!)
Full size engines have been used in aircraft, see Junkers Jumo for example. They are heavier than the equivalent petrol engine, but use less fuel, so for long range can work out Ok,
|Ian S C||15/01/2018 08:29:55|
7468 forum posts
We have a Ruston Hornsby HR 6 at our museum, and no where do Ruston call it a diesel engine, these compression ignition engines are described as "Cold starting oil engines". The HR 6 is a rather large 28hp single cylinder, horizontal engine.
Ian S C
|Mark Rand||15/01/2018 09:50:56|
|1123 forum posts|
There is no debate.
In the Diesel cycle, energy is added at constant pressure. Hence fuel injection controlled by cams or electricity.
In the Otto cycle, energy is added at constant volume. Hence the spark plugs.
Technically, the model aero engine 'Diesel' is actually an Otto cycle engine with ignition performed by compression. But it isn't a Diesel cycle.
Note:- I'm an electrical engineer, but was beaten upside the head regularly by thermodynamicists. Other cycles are available, see your local mad inventor for details .
Edited By Mark Rand on 15/01/2018 09:59:51
|Neil Lickfold||15/01/2018 10:56:03|
|750 forum posts|
There was a guy in England some where , making 4 stroke model diesel engines, that use the ether, kero,oil type model diesel fuel. So where a glow plug would go, was a contra piston that could be adjusted to increase or decrease the compression slightly. Worked quite well and they had a fairly specific fuel mix to get them to work well.
I think they only made 1 batch of the diesel's. Here is a picture of the 70 or 80 size engine a couple of pics down from the top. https://www.rcgroups.com/forums/showthread.php?1054975-Model-Diesel-Engines/page109
|Roger B||15/01/2018 11:13:32|
172 forum posts
I am very slowly developing a high pressure injection system for cylinders of around 20-25cc. The injection pump bore is 2mm as is the maximum working stroke. The injector needle is 1.5mm diameter.
The system has operated on petrol as a manifold injection system and trials using alcohol (less smelly than petrol and diesel) have reached pressures of around 60 Bar.
The details are in a thread on MEM:
I believe that you need to be a member to see the pictures.
|Howard Lewis||15/01/2018 12:49:18|
|5733 forum posts|
I agree that credit should be given to Ackroyd Stuart and Hornsby for their work on the Compression Ignition engine.
The originals used air blast injection rather than solid injection by jerk type pump.
If you want to see an example of Dr Rudolph Diesel's engine, made by Sulzer in 1913, visit The Museum of Internal Fire, near Aberystwyth. If you are lucky, they may even set it running, (takes about 10 minutes to build up air pressure for starting and injection).
Making scale injectors and injection pumps will not be easy. In full size (down to 6mm plungers) the plunger and barrel are lapped fits, ditto for the injector needle and its body, and the needle lift can be as small as 0.15mm, so you are dealing with absolutely miniscule sizes in a model.
2mm x 2mm is probably about one quarter scale for the F I E used on the subject engine, and many produced about that time, so may be achieveable.
A lot of excavators, cranes, and road rollers were powered by three cylinder engines (also tractors and gensets - still are) where the mass of the installation can cope with the natural unbalance.
(Six cylinder engines are smooth because the unbalance from one set of three cylinders is offset by that from the other) Modern three cylinder car engines employ balancer shafts and weights to deal with the problem.
The Commer TS3 was a blower scavenged three cylinder, opposed piston two stroke, so it may be possible to cheat a bit and use similar techniques for fuel supply to model aircraft two stroke engines. The port timing possible with opposed pistons and the blower,may make life easier than loop scavenge.
The Rolls Royce K Range engines were similar, but used used two crankshafts (like the Fairbanks Morse engines used in U S Submarines and Locomotives), intended for military vehicles, as was the larger Leyland engine intended for tanks. The object was to have an engine capable of running on a wide variety of fuels, by altering the phasing of the two crankshafts, via the gear train, to adjust the compression ratio.
The ultimate in multi crankshaft two strokes was probably the Napier Deltic, with three, used by the Admiralty and to power rail locomotives. This delivered 1,650 bhp from an engine about the same length as a Perkins 6.354, Ford 6D or Bedford 330, but much wider.
Good luck! and show us the results.
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