Thor

[lnvisiblemanParticipant @lnvisibleman]

Or this one with metal gears, –

**LINK**

Mike

[Dave MilbournParticipant @davemilbourn48782]

A small question just occurred to me. If by "continuous rotation" they mean that the thing will do just that i.e. carry on rotating for as long as you hold the stick over, then maybe that's not what's required. There are others which don't use that phrase – I wonder if they are restricted to 360° end-to-end? Might be worth investigating.
DM

[Dave MilbournParticipant @davemilbourn48782]

Result of investigations:

I can't find a proportional servo whose rotation stops at each end of a 360° path. All of the so-called 360° servos I've found have the magic word "continuous" somewhere in their blurb, which means they are basically just variable-speed motors-and-gearboxes.

I can only suggest a sail-winch servo like this one **LINK** with its overall travel reduced to 1 turn using something like an ACTion P96 or one of these **LINK**

As Paul's super-duper JR radio no doubt has computerised end-point adjustment (aka travel volume) then that should do the job without an add-on gizmo. It has to beat mucking about with stepper motors and controllers, innit?

We aim to please……………….

Edited By Dave Milbourn on 28/08/2014 14:44:59

[Bob Abell 2Participant @bobabell2]

Our club member….Geoff Garside, an Electronic whizz kid, had on show at Haydock, a gadget that allows a standard servo to rotate through any angle up to 360 and has six other modes

The modes are selected by blipping the trannie stick somehow

He even makes his own trannies and recievers

Paul had a chat with him at Ellesmere Port

Bob

[Paul TParticipant @pault84577]

The subject of the thrusters did occupy a lot of time over the weekends events as I explained the principals and engineering to all of the interested modellers (and there were far more than I expected)

The basis of the design is that all of the thrusters move in unison so that the thrust vectoring can be concentrated in any direction over the flat 360deg

The system has to be simple enough to operate with a basic 4 channel radio system, I appreciate that 4 channels might not be considered as basic by some but its the minimum number of channels needed for this boat.

As Dave says it would be a fairly simple task to programme a super-duper radio set to perform the task but that becomes self defeating if the prospective builders cant afford such equipment.

The following drawing shows my thoughts so far but as we all know there can be a gulf between design and installation

The main problem is knowing the direction that the thrusters are pointing especially when out of sight underwater, a stepper motor would move the thrusters in predictable stages but the operator would need a fiendish memory to remember the exact positions.

It is entirely possible to fit micro switches on the drive chain to light up LED indicators that could be positioned high up on the superstructure, these LEDs would provide a visible guide to which way the thrusters are pointing.

Paul

[Trevor HollowayParticipant @trevorholloway99134]

Personally I'd try to have a piece of equipment on deck or a flag connected to the thrusters to show the direction, could be a fire monitor for example.

[lnvisiblemanParticipant @lnvisibleman]

I'm with Trevor here. LEDs may be hard to see on a bright sunny day ( rare up north I know )

How about a couple of the crew members pointing ?

Mike

BTW this design is starting to look very tempting. Get thee behind me Paul.

Edited By lnvisibleman on 28/08/2014 17:22:03

[Paul TParticipant @pault84577]

Hi Trevor

A moving piece of superstructure is a good idea, a decca radar would be a nice unobtrusive indicator and all I would need is a flexdrive from the rear of the motor.

Hi Mike

Tempting it might be, powerful enough to pull 5t and impressive on the water…….but it wont do 50mph 30mph as per your wish…….. however a tilting catamaran with Brutus type bows (including bow mounted rudders) powered by twin 750w brushless motors will. get thee into the queue Mike

[lnvisiblemanParticipant @lnvisibleman]

PUT ME DOWN FOR TWO !!!!!

 

P S it was 40mph actually but 50 will do.  powered by a pair of these perhaps ?

http://www.hobbyking.co.uk/hobbyking/store/__29489__NTM_Prop_Drive_Series_35_36A_1800Kv_875w_UK_Warehouse_.html

Edited By lnvisibleman on 28/08/2014 18:01:28

Edited By lnvisibleman on 28/08/2014 18:05:51

[Dave MilbournParticipant @davemilbourn48782]

Paul

Do the thrusters replace the motors and rudders/Korts or are you fitting both systems?

Dave M

[Paul TParticipant @pault84577]

Dave

Both systems are being fitted so the boat will have stupendous forward power.

Paul

[ashley needhamParticipant @ashleyneedham69188]

It will also have a stupendous bow wave and would probably wash all the streering comp markers into the next county…

Invisib. Calm down plse.

Ashley

[Gareth JonesParticipant @garethjones79649]

Paul,

My practical experience of real tug control systems is virtually nil. However I have watched a few Mighty Ship TV programmes and one thing I have noticed is that the ships which have clever steering and positioning systems also have clever inceptors to control them, typically a power lever that rotates and translates, so that operation of the system is natural and instinctive. Many years ago I did do a small amount of work on the Harrier jump jet, trying to integrate aileron, rudder, tailplane, throttle and nozzle controls in a way that would reduce pilot workload. After our intial studies about 30 years ago a lot of work was done which eventually led to the VAAC Harrier, if you want to look it up on the web. One lesson I learned in my career is that systems work best if they do what is necessary. Problems often arise when people start designing systems which do lots of other things, just because they are possible.

Based on my own ability to operate a multi channel radio system I think people are going to struggle to operate a complicated control system. I am a great believer in KISS. Having stupendous forward power might seem like a good idea but in my experience of towing using a 1:24 scale TID tug, having good directional control is just as important. Getting the tow moving in a straight line is fairly easy, changing its direction is less so.

Can I offer a suggestion for you to have a look at the review of Velox in the Aug 2013 edition of Model Boats magazine. It has a completely different propulsion system but it might give you some idea how you could integrate all the systems you are planning to put in Thor but still control them from a 4 channel radio system. I am looking forward to seeing how this model propulsion system develops. it might not be the way I would do things buts its interesting and I applaud your enthusiasm to give it a go and experiment.

Good luck,

Gareth

Edited By Gareth Jones on 28/08/2014 20:55:15

[CookieOldParticipant @cookieold]

Hi Paul , I notice on your drawing that you intend to use a washing machine seal on the base of the hull at the thruster end of the system . In my opinion the seal may struggle to cope with the side load that the thruster will put apon it , It may be better to machine the housing for the seal accuratly so you could incorperate a stainless steet roller bearing and a proper spring loaded oil seal to keep the water out of the hull.It would not be a issue for me to machine up the housings for this and supply the stainless bearings and seals if required.

All The Best

Dave

[Bob Abell 2Participant @bobabell2]

Good idea, Dave, but I would keep it simple and build in a good sump pump?

Bob

[lnvisiblemanParticipant @lnvisibleman]

I thought the idea was to sell these plans to as many boat modelers as possible ?

That won't happen if a full engineering workshop is needed to build one. If I am wrong then why not go the whole hog and form the hull from vacuum moulded Kevlar and carbon fibre composites ? I am sure that Ron Dennis can come up with a price for the job.

Get real Dave.

Mike

[Bob Abell 2Participant @bobabell2]

Well said, Mike……But Dave`s an Engineer and he likes quality……and has access to it

Carry on Dave…..Ignore the Luddites!…..lol

This is a special hi-tech quality boat

Bob

[CookieOldParticipant @cookieold]

Hi Mike and Bob, I understand what you are saying , But i am concerned that the load from the trusters and also the load from the chain drive will in a very short period of time cause the seal to fail . I surpose i forget this is my field and i have full access to the kit to manufacture parts like this. It,s like when i hear Dave M and you guys going on about complex electronics i think bloody hell can we just not use a simple switch HA HA . Anyway it,s Pauls design and i am sure he will cross that bridge if he needs to in a far simpler way than mine.It,s good to be able to give some input to a thread for once instead of just asking for advice.

Regards Dave

[Dave MilbournParticipant @davemilbourn48782]

Mike

From a practical point of view I imagine that few modellers would want the complication of 360° vectored thrusters as well as the main motors and Korts. It will require a special electronic mixer of some sort to control the two thruster servo motors from one dual-axis stick (in order to keep within the 4-channel rule) and, with the cost of the four bilge pumps (and speed controllers?), stepper motors or modified servos and all the copper fittings and seals, will be prohibitively expensive for all but the most well-healed. There is also the sheer size of the thing!

I would imagine that most models will be made with just the two main motors and Korts, and perhaps a bow-thruster. As Gareth says, it will be interesting to see how things develop – but largely academic.

Dave M

[lnvisiblemanParticipant @lnvisibleman]

I suppose it all boils down to whether you want to build a boat to enjoy on the water or an engineering marvel only to be admired on an exhibition stand.

All the high cost and high tech equipment is in danger of making this just another elitist hobby for only the wealthy and well connected.

Am I the only one that wants to enjoy a nice looking model for a reasonably priced build ? I ask myself why there are so many Ford Focuses ( Foci ? ) around when Verons are available? Probably because most of the population are more realistic. My view is that this also has a bearing on why there was a noticeable lack of under 50s at Haydock Park. The hobby is in general terms much more costly than it needs to be. Whilst I am not decrying the abilities of our more skilled friends in the modelling world, or the amazing models that they produce, but my feeling is that there is far too little available, in the way of Kits/advise/tech articles etc that is aimed at the younger members of our race. If we want to encourage more younger boat modellers then this really needs to change.

Mike ( cat and pigeons comes to mind )

[Trevor HollowayParticipant @trevorholloway99134]

Talking of cats pigeons :

Wouldn't 180º thrusters and reverse work well enough – OK reverse may not be as efficient but would be easier to build and keep track of whats going on underwater.

[Paul TParticipant @pault84577]

It seems that I have inadvertently put the cat amongst the pigeons with my little project.

Dave is absolutely correct in saying that a basic washing machine seal would fail under the lateral forces and it was silly of me to title the seal in this misleading way.

The seal is actually a double lip oil seal and made from metal and nitrile rubber, it is also reinforced with a metal garter spring that maintains a constant pressure on the copper tube

On the drawing I have also reinforced the entire seal by encapsulating it within a metal frame.

Mike: The idea is to sell as many plans as possible, the problem with designing is making the subject attractive to prospective builders whilst keeping it easy for the less experienced to build. Thor will be a challenging build but certainly well within the realms of the average model builder both in experience and equipment.

Trevor: The initial design was drawn up with 180deg thrusters but I decided to go the 'whole hog' and set myself the challenge of designing a 360deg thruster system that could be built from easily available materials.

Dave: There will be a need for speed controllers for both the thrusters and motors, all within the four channel rule, for which I am going to ask for your guidance (when I know what the current draw will be)

Paul

[CookieOldParticipant @cookieold]

Hi Paul, The seal you intend to us will be fine to keep out the water , however it is not designed to take any lateral load what so ever , The housing you are locating the seal in as you know will have to be machined on the I.D to a tight tolerance ( +/- 0.05mm of the nominal spec) to accepted the seal so you may as well design the housing to take a bearing to take all the lateral load at the same time but the bore to accept the bearing will be a tighter tolerance PS the bearing are cheap as chips . Or you could see how it performs and retro fit a bearing later.

All The Best Dave

[ashley needhamParticipant @ashleyneedham69188]

This issue is getting complicated with machining being talked about.. Perhaps making the exit nozzles from ABS tube may suffice and use a sliding fit ABS sleeve over this, greased up? or even a neoprene rubber packing arrangement…and a bilge pump as suggested? off the shelf engineering.

A machined nylon sleeve and "o" ring would be my suggestion for lathe work.

Bearings are also available with built in seals one or both sides.

Ashley

[lnvisiblemanParticipant @lnvisibleman]

Ashley/Paul

Is this the sort of thing you are talking about ?

**LINK**

Mike

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