Jawfin Posted June 21, 2013 Share Posted June 21, 2013 Hello,I'm mainly asking larger scale modellers here (hopefully this is the right section), but are there any live diesel producing companies still out there, and has anyone built their own? Link to post Share on other sites More sharing options...
ZiderHead Posted June 22, 2013 Share Posted June 22, 2013 Although I like the idea of it I think theres a fundamental problem with live diesel as opposed to live steam, and that is the sound. Whereas most real diesel engines in locos work at under 1000rpm, RC aircraft engines buzz around at, what 15,000rpm? and that just destroys the illusion. It literally screams model. I'm not sure if its even possible to build low rpm/ high torque miniature engines that would fit the bill, perhaps long stroke and a slow but clean burning fuel oil might do it, but you'd have to have multiple cylinders. A flat 4 might give a good dieselly throb but packaging would be a problem ... all in all its quite the engineering challenge. edit: that said this is the best sounding live diesel Ive heard, would like to know more about the engine used: Link to post Share on other sites More sharing options...
DavidB-AU Posted June 22, 2013 Share Posted June 22, 2013 Here's another one, built by the legendary Bob Symes in the 1970s and still running. CheersDavid Link to post Share on other sites More sharing options...
Titan Posted June 22, 2013 Share Posted June 22, 2013 Even a small RC engine will develop way more power than is required for a loco, so it is possible to run it at much lower rpm than would be necessary with an aeroplane. Having said that it is still going to be quite high, even at tickover they will probably run at a couple of thousand. I would expect for the slowest speed and best sounding engine, see if you can get a four stroke engine that will fit, give it a larger flywheel, and change the glowplug for a hotter running one, so at low speed it does not get too cold and stop working, Should at least stop it sounding like a demented chainsaw! Link to post Share on other sites More sharing options...
ZiderHead Posted June 22, 2013 Share Posted June 22, 2013 That sounds about right, I suspect that western has a 4-stroke and a rather heavy flywheel. I bet someone on rmweb knows the guy who built engineered it and could tell us Link to post Share on other sites More sharing options...
PatB Posted June 22, 2013 Share Posted June 22, 2013 The Bob Symes 47 had a Taplin Twin, a homebuilt two pot, two stroke compression ignition engine designed in the 50s/60s, with water cooling and running at, by modern standards, fairly mdest rpm. I forget exactly what but it was driving a Lucas 6V motorcycle dynamo which I wouldn't expect to be happy much above ~6000. Better generator technology is now easily available. Many motorcycles have had small, permanent magnet alternators which could probably be suitably mounted and squeezed into something in, say 16 mm scale or above, making an IC-electric an entirely practical proposition. RC car and helicopter engine installations are designed to operate at high power outputs with limited natural cooling air flow so engine technology is easily and relatively cheaply available. Might need a big box of a muffler to make the noise bearable, though. As an alternative powerplant, for those with considerable skill in the model engineering field, this might be suitably thumpy and torquey and may just about be shoehorned into a reasonable loading gauge for something eccentricly narrow-gauge. Link to post Share on other sites More sharing options...
Titan Posted June 22, 2013 Share Posted June 22, 2013 And don't forget, any dc permanent magnet motor will also work as a generator, but the voltage will be a little less i.e. a 12V motor when spun at its no load speed will generate a little less than 12V. A 12V motor used as a generator to power 6V motor(s) might work quite well. Link to post Share on other sites More sharing options...
nathan9117 Posted June 23, 2013 Share Posted June 23, 2013 I am a multi model man and what I mean by that is I have model trains as well as model cars. The short answer is Yes there is "Live Diesel" but the long answer is a bit of both. You can get working model engines as you know and you can modify them to run on different types of fuels. I have seen rc nitro engines converted into diesels before but as stated above they run at significantly higher rpm than a large engine does and this is due to the fact the engine needs to stay spinning fast enough to keep turning. With a large engine in your car it has a much larger and heavier flywheel of course and so that means more centrifugal force when it spins to keep it going. You could probably get a nitro engine to tick over at about 12,000 rpm but it would take alot of work and a heavier flywheel as well as fuel mods and finding a small enough diesel glow plug to work in the engine. I would say the smallest gauge diesel you could use to make it sound and operate realistically would be a 2 stroke diesel engine from a generator or a garden lawn mower or strimmer that sized engine would fit inside the garden gauge trains like the ride on ones. 7 inches to the foot i think they are ? anyone ? Anyway if you had the time and money you could make a small 0 scale diesel but it would be a long process of trial and error. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted June 24, 2013 Share Posted June 24, 2013 ...I'm not sure if its even possible to build low rpm/ high torque miniature engines that would fit the bill, perhaps long stroke and a slow but clean burning fuel oil might do it, but you'd have to have multiple cylinders. A flat 4 might give a good dieselly throb but packaging would be a problem ... all in all its quite the engineering challenge. A challenge alright. The primary problem is obtaining the necessary compression at slow revs. As cylinder diameter reduces, the leakage rate round the piston rings rises: this can be overcome by high revs (easier) or precision engineering (expensive, problematic). And these low revs won't yield the bass end of the prototype sound output; simple audio physics, the 'organ pipe' of cylinder/exhaust duct length defines the bottom fundamental. (Same applies to steam of which there are plenty of running examples to hear, the 'whoomph' at around 100Hz of a big loco starting, is reproduced as a high pitched 'whiffle' circa 4kHz by a true scale O gauge model. Very disappointing. We need to operate in a very rarefied atmosphere for scale sound.) I loved the fellow with the Warship in the first vid clip at 1.30. He went for a fix, but honestly he didn't inhale, despite appearances... Link to post Share on other sites More sharing options...
nathan9117 Posted June 25, 2013 Share Posted June 25, 2013 Ill see what i can do with a bit of pipe as an exhaust for a model engine to see if i can muffle it and make it sound bassy lol Link to post Share on other sites More sharing options...
ZiderHead Posted June 26, 2013 Share Posted June 26, 2013 The smallest OS 4-stroke would juuust about squeeze into a 10mm loco and they run up to 10-12,000 rpm. A CL37 V12 runs up to 900rpm? so thats in the ballpark, the key would be to tune the exhaust as mentioned above ... maybe its not impossible to get a live diesel-electric sounding good ... Link to post Share on other sites More sharing options...
Titan Posted June 26, 2013 Share Posted June 26, 2013 If a class 37 v12 runs at 900rpm, then a single cylinder four stroke would have the same number of power strokes per minute running at 10,800 rpm. Link to post Share on other sites More sharing options...
ZiderHead Posted June 26, 2013 Share Posted June 26, 2013 Indeed Link to post Share on other sites More sharing options...
nathan9117 Posted June 27, 2013 Share Posted June 27, 2013 If you can get the correct resonance to create enough pressure in the exhaust then you will be able to keep it idling at low rpm thats the main problem with the engines the small model ones need enough rpm to idle other than that problem you would have no issues . Link to post Share on other sites More sharing options...
jessy1692 Posted August 19, 2013 Share Posted August 19, 2013 Ive always wondered what the model t9 29 baby deltic model in the railway museum would sound like, looks to be a very well crafted deltic angine plus generator i think in guage one Link to post Share on other sites More sharing options...
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