Hi Colin
Now that is interesting as it has set my mind off on a different thought path, model azipods. But that is a different story for a different thread another day.
While it will do the same job, its design is different in that we are looking at putting the motor around the prop blades as opposed to motor in the centre. Thus mimicking the real world that RR and Voith market solutions for with their Tunnel Thrusters.
I am guessing Doug is correct with his workshop capabilities and cost observations on the tunnel drive. Maybe one day when the kit is available....... Who knows what is possible?

Maybe this will help, found on Web.

Was just pulling your chain Ian 😉
Anyway you're gonna need a damn well equipped workshop to clone that stator,
And wind so many small, but balanced windings!!
There must be a reason why they're so expensive.

Cheers, Doug 😎

Err!! Not my intention.
Clone the motor design and wind a waterproof one then add the scimitar blades into the centre of the brushless, and you would have the tunnel drive??

318.40 € !! Phew 😮
Voith Schneider in a tunnel!!??
Wie geht denn dass??
😎

Guys It is a different beast, but is this a potential start point for the direct drive tunnel thruster. It is a thin direct connected brushless motor !

Many a true word spoken in Jest!!

And now to the next issue to natter about

Doug, yeah, leaving them in water to see if the VP will shrink is obviously a non starter. I guess you could nip down the road an hour or two and see if you can find a Swiss Watch Maker who could get it down to 30mm Dia. If you do find one, I will order a couple of 40mm for my tug and a further on for my trawler.
As to the Magnetic Motors, for me its about space in the model to fit enough generation capacity to meet the full load requirements.
Assuming the load current can be generated, a method of switching in or out the magnetic gen sets as the load varies will be required. I am assuming that you will need more than one unit.
Then, as you say we need a direct reversing ESC that will handle both the load and the power from the magnetic get sets as opposed to the nice smooth supply from a battery.
Big Boys Toys like ships and rail locos have a Thyristor Bridge to do it, We could use suitable transistors or high current power micro circuits to build a DIY one.
Having said all this, is it a value solution to save the fitting of a battery? Loads of different views and issues to weigh up for each modeller to reach there own conclusion. For now I have to much invested in batteries, not only as power sources but also as ballast!

That was a joke DG.
Remember those?

"Must have a look to see if it's got a Variable Pitch Drum!"

If it's direct drive the pulley which drives the drum will actually be a brushless motor built directly onto the shaft. Which should improve bearing wear no end, as the old belt used to give a lot of side load...

My machine is pretty quite as well.
Must have a look to see if it's got a Variable Pitch Drum!😁
😂🤣

Much like what they have done with washing machines. I'm amazed at how quiet a direct-drive machine is on full spin....

That is a fantastic bit of engineering.
Very clever.

Martin.

Brilliant Ian 😮
Now if he can get that down to 30 to 35mm diameter for me .......😉
Doug
PS "you could mimic big ship practice"
Hm! You'd still have the speed control / reverse problem though.
Constant voltage charger for the drive battery maybe?
Would need a bit more electronickle to regulate the charging though.

Morning Doug
Yeah if they have enough grunt to turn a generator you could mimic big ship practice, diesel electric or in our case magnetic electric. Anybody good with numbers to see if it will work
As to variable or controllable pitch props, take a look at this You Tube Clip, great model engineering.
Ian

I agree Doug,
Early days, who knows what the future will bring.

Martin.

Hi Martin,
"This type of motor would be good if you could control the speed."
Since the motor uses permanent magnets on both stator and rotor the speed will also be permanent and unalterable, as both magnetic fields are constant.
To alter the speed of the vessel (or go astern!) you would need to alter the pitch of the prop and hence the thrust. 'Variable pitch propellers!'
This is the operating principle of constant speed turbo-prop aero engines for example.
VP props are also used on many ships these days.
Needs some intricate gearing built into the prop hub, and controlled by !? 🤔
Control shaft running inside a hollow prop shaft?
Don't know of any model versions on the market so if you find one, or come up with a way to DIY one I'd be MOST interested.😉
A constant speed version driving a generator might be useful though👍 IF it has enough torque. Might work with a decent gearbox?
Cheers, Doug 😎

Hi `Doug

To be absolutely correct the ship I was on did not have Kort Nozels as it has a pair RR Azipulls, which have an inboard electric motor driving what is in effect a 360 deg rotating Schcttel Drive. The props aways face clean water as they face the direction of travel, un like a conventional shaft drive where they face aft and have loads of boat in the water flow.
As with most electric ships 2 engines give normal cruising speeds of around 12 knots, for 15 you need another diesel on the line!
It was interesting to see the actual controls. A knob about the size of a tennis ball with a small lever that moved through 90deg per Prop .Top dead centre was stop, all the way to horizontal was full power.
The ship is MS Fram and she took us to 68deg 17 South !! An absolutely awesome voyage!! But this is maybe a tad off point for this thread.

Guys, while I am a RR fan as always there is someone else out there doing the same. Voith have some great real world bits of kit too.
Ian

Now that's a great idea!👍

Cheers, Ed

Hi Guys,
This type of motor would be good if you could control the speed.
There will be no need for a main battery for the model, you could also drive a motor generator to keep the receiver battery charged.



Maybe one day!


Martin.

G'night Doug!

I'm putting her on auto pilot!

Night all!🙈🙉🙊

Mornin' Commodore,
You have command Ed.
I'll be in my stateroom.
G'night all 😎😴

No sweat Ed 😉
ALL you have to do is take a brushless Inrunner apart,
build the stator coils into an aerofoil section nozzle ring
(same cross section as an aircraft wing) with the "underside of the wing" on the inside of the nozzle and the blunt end up front,*
then JUST graft some neodymium magnets onto the ends of your prop blades 😮 balance and polish.
Then just install your nozzles where you would normally fit the rudders.
Use a 360° servo for steering control.
Easy peasy 😁
Interested to see who does it first😁
Cheers, Doug 😎
* Effect of this is to increase the water pressure inside the ring and decrease it on the outside. Thus improving the efficiency of the prop / impeller.

Great Idea!

Wonder how long before.
we'll have one for our models!

Cheers, Ed

Absolutely agree Ian,
That's why my comment about pods refers only to the elimination of the separate motor / gearing and came before the comment about nozzles!
BTW What ship was that?
Cheers, Doug 😎

Hi Doug Nice advert spot as you say.

When used as a Tunnel Thruster the argument you raise about foil shape and astern running may apply.
However when fitted to a fully Azmuthing Pod, one that turns through 360 degrees the problem goes away as to go astern you just turn the pod the other way.
Well that was how a Chief Engineer explained it to me a couple of years ago. The other point he made was the prop is always turning in it's optimum direction, you just turn the pod and therefore the thrust!
The ship was very quiet indeed as all the power plants are Gen Sets on resilient sound deadening mounts, just a power station of 4 MaK straight six turbo charged diesels.
Ian

A nice advertising spot Martin👍
In essence what they've done, and quite neatly apparently, is to take a Kort nozzle and eliminate the engine inside the hull, and associated gearing, and build the essential elements of a brushless (induction!) motor into the nozzle shroud and the propeller, or impeller or rotor depending on form factor and purpose. The scimitar blades are typical low noise sub screws.
You could equate it to an inrunner brushless!

Same applies to the so called motor pods. This design eliminates the separate motor and propeller in the pod and combines them in one unit.

Disadvantage of nozzles is that they loose their advantages at speeds above about 10 knots or so, and are not very effective when going astern. Main reason for that being that the shrouds have a section like an aerofoil section to achieve their effect, so when going astern the foil is the wrong way round🤔 Maybe RR found a solution to that, but they didn't elaborate on it in the advert.
Cheers, Doug😎

I have been thinking with the idea of magnetic motors and trying to get away from normal propellers.
At the moment I am unable to spend much time in my little workshop (health reason)
So I have had these crazy ideas buzzing around in my head.
Normal this leads to me making something different.

Martin.

I have been making mould tools for Stators and Rotors for years. Wonder what they have been used for. Much smaller scale though.😎

Hi JB,
Perhaps he means very little cavitation or less friction.
I have been trying to look for some sort of propulsion that is not water jet or standard propeller.
As you know I like to tinker.
Maybe it is something that I will have to try and design.
Some years ago I seem to remember that China or Japan had a system that was so different to all other normal propulsion systems, but I cannot find it anywhere.
Perhaps I dreamt it!

Martin.

Hi Martin, That guy better brush up on his English, (hardly no cavitation - does he mean there is or there isn't any !???) I don't know why we went to school. The standard of English in some of the ads and papers here is pathetic (TV and billboard ads). Nobody seems to proof read any more
I don't know if you remember back to the 60s where Hornby came up with a 'ring field motor' which was a very thin, large diameter motor for their engines. It could run on DC for high speed and AC for low speed, and even though not the same as the motor in the vid it had a similar profile. Reminded me of it immediately.

So now you know how our brushless motors work as well Martin 👍
Giant versions must be driving HMS Queen Elizabeth and the T-45s.
😎