RC Locomotive 'Diesel-Electric'

[tudordewolf]

A battery loco is very much my fall back position, but the reason why I am pursuing this is because I know it’s possible and at a smaller scale than I am building it. 1 7/8” gauge, the model was a British diesel electric loco built by a fellow called Bob Symes, he featured in a number of UK TV programmes on model making in the 70’s and 80’s many of which are viewable on YouTube. His model used a genuine diesel engine, a now vintage Taplin twin running on castor oil and ether, of around 8cc I think. He later converted it to a glow plug engine and made it Radio controlled.

Watch from 3:26

Another one I've found is another UK locomotive a ‘Hymek’ at 3 1/2” gauge, this one uses a home made multi cylinder engine and I believe its hydraulic drive, which would be correct for the real loco type, very unusual as I have not seen another use this drive system.

So you can see, it must be done! :0)

And if I fail, then I can always fill it with batteries. :0(

Both those locos are amazing. I love the tiny, real fuse panel on the second one.

I'm realizing I may have misunderstood the overall scale of yours, I thought you might be working towards something ride-able or able to pull people on a small gauge railway. If it's just going to be moving itself and pulling a few cars, it won't need anywhere near the power we've been talking about. I think you could consider something a lot smaller, maybe even the 8cc "Enjomor GS DK01" - (video)

 

[Roog]

Both those locos are amazing. I love the tiny, real fuse panel on the second one.

I'm realizing I may have misunderstood the overall scale of yours, I thought you might be working towards something ride-able or able to pull people on a small gauge railway. If it's just going to be moving itself and pulling a few cars, it won't need anywhere near the power we've been talking about. I think you could consider something a lot smaller, maybe even the 8cc "Enjomor GS DK01" - (video)

An interesting comparison are the 3 1/2” gauge steam powered locos do haul passengers at the club, I doubt if they make more than 600 to 800 watts power, given that my loco will be RC I would be content with hauling carriages, but it should be capable of passenger movement.

I built a 56” long RC steam tug with my father back in the 70’s, that used a twin cylinder Stuart turner engine, gas power input maxed out at 3000W, 9000BTU, and we only used that when first raising steam, I very much doubt that the power conversion factor to the propeller was even 10%, which means our steam tug probably made 300W at best and that easily towed a couple of people in a rowing boat behind it.

At the end of the day, if the IC generator partially recharges the batteries during a run I’ll be content.

 

[Roog]

Both those locos are amazing. I love the tiny, real fuse panel on the second one.

I'm realizing I may have misunderstood the overall scale of yours, I thought you might be working towards something ride-able or able to pull people on a small gauge railway. If it's just going to be moving itself and pulling a few cars, it won't need anywhere near the power we've been talking about. I think you could consider something a lot smaller, maybe even the 8cc "Enjomor GS DK01" - (video)

I like that the DK01 has electric start , that’s living it up! :0) I've noticed quite a lot of four stroke engines for sale, they are clearly the preferred motive force behind large RC planes.

 

[tudordewolf]

I like that the DK01 has electric start , that’s living it up! :0) I've noticed quite a lot of four stroke engines for sale, they are clearly the preferred motive force behind large RC planes.

There's really no comparison to the putter of a purring 4-stroke, I flew mine today; the one in my profile pic.

I'm starting to think that the DK01 may be a really good candidate, it even runs on gas (or glow, if you want) and won't break the bank. Looks like it comes with a "standard" nitro pull-start, you could go electric or shaft start with various options, or the VESC method you mentioned.

The dimensions are pretty compact, too, looks like the flywheel sticks out more than anything else - you could probably machine a smaller one from brass to match the rotational inertia:

 

[Roog]

There's really no comparison to the putter of a purring 4-stroke, I flew mine today; the one in my profile pic.

I'm starting to think that the DK01 may be a really good candidate, it even runs on gas (or glow, if you want) and won't break the bank. Looks like it comes with a "standard" nitro pull-start, you could go electric or shaft start with various options, or the VESC method you mentioned.

The dimensions are pretty compact, too, looks like the flywheel sticks out more than anything else - you could probably machine a smaller one from brass to match the rotational inertia:
View attachment 271279

Cheers @tudordewolf I'll check it out.

 

[Roog]

Currently contemplating buying a honda gx25, and strip it back to its bare bones engine. Will hopefully be more refined if less powerful.

 

[Roog]

Today i have been making belt tensioner arms. These pivot crudely about a screw and a set screw which i can tighten and lock off to set the tension. The belt runs on three ball bearing races side by side acting as a roller mounted on a brass ‘pin’.

Ill put it together and photograph it in situ.

I roughed out the shape from rectangular bar using the mill, then cut the circular hub using my boring tool in reverse, (outside in as it were), not great but got me the shape I needed, and it was better after sanding!

Then on to the bearing ‘Pin’

Cutting a slot in the head with a tiny end mill, very satisfying and much neater than sawing and filling

Finishing off with a bottoming tap for the thread.

Now looking forward to finishing the two locomotive trucks complete with motor mounting platform ready for motors.

Then i can get on with the chassis

 

[Roog]

Ill stick em on the truck, when i get all of the parts together.

They do look a bit chunky, looked good on the drawing!

 

[CertifiedMike]

Ill stick em on the truck, when i get all of the parts together.

View attachment 272016

They do look a bit chunky, looked good on the drawing!

I need to build a mini version of these for my Kyosho Lazer belt. Mine won't be quite as pretty or chunky tho!

Will these be spring loaded or tensioned by the screws alone?

 

[Roog]

I need to build a mini version of these for my Kyosho Lazer belt. Mine won't be quite as pretty or chunky tho!

Will these be spring loaded or tensioned by the screws alone?

My experience with my electric belt drive tether car suggests that the belts are actually very stable and setting the tension mechanically works fine, however I agree with your 'leading question' (0: is that the proper engineering solution is of course a spring loaded arm and this can be incorporated.

 

[Roog]

Some pictures of the nearly complete trucks at roughly the correct distance apart on the track (probably slightly too close together)

A look at the tensioner underneath

 

[CertifiedMike]

My most favorite RC (Kyosho Optima Mid) is 4wd, timing belt driven, just like yours. This one doesn't really need a tensioner (yet) but I have a Kyosho Lazer that does need one installed. It helps to function as a guide so the belt doesn't hit the gear case at high rpm.
The Kyosho TF3 in front of me also uses a couple tensioners.

I have had great luck with belt drives. I think its a good idea. It will be nice and smooth, quiet too! No gobs of grease to deal with... Very smart!

The trucks look amazing! You are exceptionally tallented! I wish I were able to machine parts like that.


Seeing the parts all come together is awesome!

 

[Roog]

My most favorite RC (Kyosho Optima Mid) is 4wd, timing belt driven, just like yours. This one doesn't really need a tensioner (yet) but I have a Kyosho Lazer that does need one installed. It helps to function as a guide so the belt doesn't hit the gear case at high rpm.
The Kyosho TF3 in front of me also uses a couple tensioners.

I have had great luck with belt drives. I think its a good idea. It will be nice and smooth, quiet too! No gobs of grease to deal with... Very smart!

The trucks look amazing! You are exceptionally tallented! I wish I were able to machine parts like that.


Seeing the parts all come together is awesome!

Thanks Mike, I’ve said it before, the encouragement, critique and advice I have received in this place is a credit to the members, thanks to all. I was initially sceptical re using ‘timing belts’ for transmission but following my experience with my very high reving electric tethered car it has turned out to be the least troublesome part of my car and it makes alignment less critical and allows easy gear ratio changes. I had little hesitation in choosing toothed belts for my loco. I can see some kick back likely from the model engineering club members who believe in metal gears and chains, rubber belts are going to be a step too far.

It’s good to get a couple of key assemblies built, I should be able to get on to the chassis soon, then the full scale of the thing should begin to be apparent. Then I can start to complain about the difficulty of making the scale body work.

 

[Roog]

Trucks stored in their ‘oil proof’ box, the carpet in my office has taken a hit or two, which reminds me I’m going to have to paint this lot black soon before it goes rusty!

 

[CertifiedMike]

Thanks Mike, I’ve said it before, the encouragement, critique and advice I have received in this place is a credit to the members, thanks to all. I was initially sceptical re using ‘timing belts’ for transmission but following my experience with my very high reving electric tethered car it has turned out to be the least troublesome part of my car and it makes alignment less critical and allows easy gear ratio changes. I had little hesitation in choosing toothed belts for my loco. I can see some kick back likely from the model engineering club members who believe in metal gears and chains, rubber belts are going to be a step too far.

It’s good to get a couple of key assemblies built, I should be able to get on to the chassis soon, then the full scale of the thing should begin to be apparent. Then I can start to complain about the difficulty of making the scale body work.

If dragsters can use belts on 3000hp big block blowers and Harley Davidsons use them on primary and final drives, your train should be just fine I believe.

 

[WRM]

In the lates 80s my only RC car was an Optima (pre "Mid") that I bought used. I used it a bunch for indoor carpet and ovals and had a set of MT tires w/buggy body for bashing. Never had a single issue with that belt drive....

 

[Roog]

In the lates 80s my only RC car was an Optima (pre "Mid") that I bought used. I used it a bunch for indoor carpet and ovals and had a set of MT tires w/buggy body for bashing. Never had a single issue with that belt drive....

Yup @WRM and @CertifiedMike I agree belts and toothed belts in particular are a mature technology, although I do like a chain on my bicycle and I was relieved to find that my car has a timing chain!

 

[WickedFog]

Kyosho belt drives are sweet! The Javelin with the chain drive sounded like Dennis the Menace coming down the road.

 

[Roog]

Kyosho belt drives are sweet! The Javelin with the chain drive sounded like Dennis the Menace coming down the road.

@WickedFog What you have”Dennis the Menace” in the US? :0)

 

[HPIguy]

The only place I ever had belt drive issues was on-road in dirty parking lots. One tiny pebble at 70+ mph will really ruin your day.