lkydvl

I am looking for an engine to use in constructing a G scale locomotive. It will be used to drive a small motor as a generator to power the motor blocks. What engine 2 stroke or 4 stroke will run smoother with less vibration at under 12000 -15000 RPM?

Is a diesel any smoother running ?

Thanks

Andre'

pikebishop

doesn't saito make steam engine replicas?

loading

Very cool idea. A glow genset for your train. In general, a 4 stroke has more vibration than a 2 stroke. I am not sure about diesel. I would think that the 4 stroke would sound much closer to what you would want. And, again generally they produce more tourque at lower RPM's. So, it would sound even better with the right gearing. You might also want to tap the car guys for info. For the size of motor you need and your application, a car motor would be probably be what you want. I can't remember where (Tower maybe) but I thought I saw a 4 stroke car motor from OS. Are you going to use some sort of helicopter governer on it? I just kinda rammbled on here, but I just thought the idea was so neat, that I had to respond with what little I know.

Motorboy

The dieselengines has more power than the glowengines, less fuel consumption.

Jens Eirik

shain

My Feedback: (1)

The diesel runs pretty smoothly and has great amount of torque. However a diesel and 4 stroke runs at lower rpm than a 2 stroke glow.

William Robison

My Feedback: (3)

Andre':

Your biggest problem will be cooling. This argues in favor of a helicopter engine set, and two stroke as they generally are the coolest running.

The engine itself, unless you use an engine intended for ducted fan, isn't going to run the 25K to 30K you'll need for efficient power generation. Pick the engine you want, check it's torque peak rpm, and gear it to run the generator around 30K rpm.

Then if you use a "Brushless" motor feeding into a full three phase rectifier you'll have a pretty good generator set. You can select the motor (generator) to get the voltage and current you want. Bearing in mind the engine power being available to turn the generator at that output.

I suggest using a brushless motor, it will give you the high current through a lot longer life than a brushed motor would, as well as having a higher current capability.

Bill.

lkydvl

Bill,

Thanks for the info. I have installed cooling fans into the top of the long hood of the SD45 and planned on haveing another inside blowing past the engine. Your info on motor speed specs and the use of a brushless motor were new to me. I have NO knowledge in brushless motors.

However the standard brushed motor mfgs cautioned me to not try exceeding 12000 RPM with a standard motor as they wouldn't last long before throwing and armature or self destructing by other means.

I have located several DC brushed motors that will produce the voltages and amperage I want at RPMs from 5000 to 11000 RPM. That should allow me to run the .15 engine I have at something less than full speed.

This eliminates a gearbox requirement and I can connect it with a standard clutch setup from a car/truck.

If you could provide me with a recommendation on a brushless motor to provide up to 24 volts and 5 amps I will look into that also. I have not purchased the DC motor yet so am still open to other choices.

Thanks

Andre'

bob27s

My Feedback: (19)

To package something like that inside of a G scale might be tough.

But let me suggest maybe using the OS30 FS. Its small, smooth, quiet.... and with a proper governor/throttle you can set what ever rpm you want. I have a OS26FS that is over 10 years old, and it still runs like a watch.

[link=http://www.osengines.com/engines/osmg0830.html]os 30 engine[/link]

You will want to run it below 10000 rpm, so you will need to govern it somehow.
Maybe use something small and lightweight like a [link=http://www.modelavionics.com/pro/]throttle jockey[/link]

If the genset does not have a lot of mass, perhaps add a steel marine-type flywheel on the engine... maybe incorporate a fan/flywheel combination for cooling ?? usually the marine flywheels were cut with a groove for a starting belt...which may come in handy as well.

Chances are with the type of electrical load you will likely utilize, you will never have to run that thing above 1/2 throttle. It will run all day on 6oz of fuel And running at that power setting, it will run fairly cool as long as you keep some air moving over it.

Saito has a small 30 size 4 stroke too. check that one out as well.

If you need higher RPM on the generator..... gear up from the engine rpm. There is pleanty of power available, and with a flywheel you will not have any torque problems under load. For your application, this is likely a whole bunch more practicle, and a lot quieter, than having a screaming engine in the cab.

Good luck with your project

(edits, added links)

rmh

A spring?
I got a spring powered train set -for Christmas in 1943 - it was quiet and dependable -till my little brother did an analysis of it's innards--

William Robison

My Feedback: (3)

Andre':

Your last post mentioned 24v at 5A current. This 100W is over the maximum sustained power for a can motor, and your 10K rpm limit suggests that is what you had in mind. Additionally, I don't know of any that operate at 24v, you'd have to go with 12v at 10A current. And that is too much for the brushes in a can motor. A good "Cobalt" brushed motor could easily take 10A through it, but you can also get one would for 24v with no trouble. And it will operate happily all day long at 20K rpm or higher with its ball bearing support of the armature. Staying at a 10K limit will lower the efficiency also. But the self rectification through the commutator and brushes will be the biggest loss. By eliminating the brushes you also eliminate the items of greatest wear.

If you are at all familiar with AC electric motors you know about three phase motors, and their greater efficiency compared to single phase motors. The "Brushless" model motors are three phase units, the ESC converts the DC th 3P ac to run it. Since the model motors use permanent magnets instead of induction in the armature, they can be used as three phase generators, just like the alternator in your car other than the DC feed to the rotor in your car's unit. A similar six-diode bridge will convert the 3P generator output to a really clean DC, rather than the "Notchy" peaked output of a brushed DC generator. Each diode in the rectifier pack will have to be rated for the maximum system current, and probably be mounted on a heat sink as well. Both these will add to the cost, but just a small amount.

You will have to have some form of voltage regulation. The alternator in your car is controlled by varying the power into its rotor, changing the strength of the rotating magnetic field. Using permanent magnets you'll have to use external regulation, independent of the generator.

The only disadvantage, when compared to a 550 or similar "Can" motor is the cost. Compared to a cobalt brushed motor though, there's not that much difference in the cost of the generator set. Either one will need some form of voltage regulation.

Just a thought - If you replace the truck motors with 3P motors as well you could then use a battery set as part of your voltage regulation, and with some radio controlled jiggery-pokery in switching you could operate the "Generator" as an on board starter for the engine, then switch things back and drive the truck motors with the same ESC.

As Bob27 said, you will need a throttle controller for the engine, you could use an ordinary RC servo in parallel with the ESC for the truck motors to throttle the engine up when you call for more power to the trucks.

Hope I've made my thoughts clear.

Bill.

William Robison

My Feedback: (3)

Andre":

Sorry, forgot to mention one point. There is no need for a clutch, the generator load will be almost nil at idle.

Bill.

bilou

Rotary engine O.S is certainly a non-vibrating engine, but it runs hot and drinks far much then the other engines. Lowest T° DIESEL, then 4 stroke, then 2 strokes. I uses all so i know what i'm taking about.