mini models power units and control

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Dear All,

 

I am anticipating two models which will require miniature power supplies and controls. The first is a Thames barge of about 5 1/2″ in length which will require receiver (2.4Ghz) 6V supply (two 3V digital camera batts wired together) and two servos rudder and sail arm. The batteries are intended to be attached to a small fin for stability and sailing purposes.

The second is a small “fishcutter” based on a card model again 6″ maximum overall length, requiring receiver (2.4 Ghz) 6Vsupply, an ESC and rudder servo. I have mini ESC used for flight but it is forward only (very light weight) could this be re configured like the Mtroniks Viper units to forwards and backwards?

There should be images attached to this.

 

Any suggestions, sources for mini systems etc please. I do anticipate using a servo motor for the power unit on the FV, but still need to source shaft and propeller, or make my own.

 

Thanks Kimosubby.

 

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

6″ models and less

[TelstarParticipant @telstar]

Hi Wow thats small.

I fitted rc to a 11″ model and I thought that was small.

At first I used a dismantled standerd servo with the circuit board slightly modified driving the servo motor, while this worked I had little speed control (It was either off or full ahead/astern).

In a further itteration of the boat, I used a ACTion micro esc

http://www.action-electronics.co.uk/pdfs/P52A.pdf

it is better.

The servo for rudder is approx 3/4″ x 3/4″ x 1/4″ including shaft, and I got them on Ebay.

The prop shaft I think was Graupner 2mm shaft dia , 4mm tube dia ,100mm long, (you would have to put the motor in the figurehead)

Also the smallest prop, fits the 2mm shaft but is 25mm 3 bladed,.

 

Hope this is of some use Tom

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hello Tom,

thanks for your thoughts.

 

I’ve sourced some really micro servos on the servo shop web-site and have a power unit idea from the component shop. There are some really small receivers too, so its really an ESC and shaft/prop which I think I’ll make myself. I’m sticking with the servo motor for drive, but removing everything else from it.

Looked at the P52A, its bigger than all the other gear together, I might get one and try and shrink its size – at least loose the cover!

The sailing micro barge should present fewer problems – no speed control, no motor, just receiver, 2 x servos and a power pack currently 52g all together!

 

I’ll keep this post posted!

 

Kim

 

 

[Dave MilbournParticipant @davemilbourn48782]

The P68A is quite a bit smaller than P52A, especially if you leave it out of the (substantial) ABS case. Weight without that is 9g. Just put a piece of heat-shrink tube around it to insulate the board from anything else live.

Suit yourself.

Dave M

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Dave,

that sounds good – saves another few g and more importantly is a fair bit smaller to fit in the space available.

I see you’re into tugs/fire fighters what with all that water spraying about!

Kim

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Well I’ve taken the plunge and ordered bits and pieces for these two small craft. Without being able to handle the goods before purchase, I dealt only with trusted suppliers I’d dealt with before, and tried to get the lightest items available.

 

Requirements for the barge: two mini servos (sail and rudder), receiver, 4.8V power source.

 

For the FV: one mini servo for rudder, receiver, 4.8V power source and a speed control with forward and reverse function if possible, motor.

 

Calculated available mass for the barge was assumed to be half the total – about 50g. All the bits for her, without making further savings came to 47g – success

 

 

For the FV, although seemingly bigger, and probably is with the curved hull shape etc, allowed a guess at 75g – all the bits came to 72g again without any trimming, though a shaft is needed which I hope to be nylon and a nylon prop too.

 

For those interested, the power units will be 4 x 1/4 AAA batteries (12g total) with a rating of 120mAh. I do have another set of 1/3 AAA (18g) rated at 150mAh.

 

I now have scale endurance as well as scale speed and scale size. I don’t anticipate sailing them too far out – they look small on the table!!

 

Kimosubby

 

[ashley needhamParticipant @ashleyneedham69188]

I was in a model shop a week ago and asked after small brushless motors, and the chap pulled a box out of the cabinet with an out-runner brushless motor in it the size of 3 pennies stuck together….and it was 40watts worth. truly outstanding. And very light.

 

Forget which model, but it a “Park” motor of some sort.

 

I have a Park370 a 3600Kva in-runner on one model,….20mm diameter by 30mm long….takes 12V and delivers at 10A…..oo er.

 

Ashley

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Ashley,

 

that sort of power for something so small leads to an idea – could we scoop out a Li-po and make it the hull? That would keep things quite small!

 

Kimosubby

[ashley needhamParticipant @ashleyneedham69188]

OOOOh no no no…dont li-po`s blow up if short circuited or something !!! I would leave them well alone.

 

Your best bet for small and light would be to make the hull out of solid, and then get a vacform moulding off it. You could use possibly 0.5mm plastic and it would weigh almost nothing. Trim and paint, all that would need doing to it…

 

it might also be possible, at this very small size, to make a propshaft tube out of Plastruct tube…the tubes telescope into one another, and you could use 2mm internal diameter tube bits as the bearings and whatever these bits slot into as the actual tube.

 

Ashley

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Just joking about carving a battery, wouldn’t float anyway.

 

The vessels are actually 100g grade recycled paper! Made this way, they can be just a static display. OR just varnish inside and out for proofing, and voila! The FV is a kit from Marcle models, but the barge is my own concept, so to speak.

 

Dave at Action has come up with v small rec units and suggested v small motors. I have their P68A already for control.

 

I was going for a 1mm shaft with integral 3 blade prop, have thought of using the aeroplane control linkages, they’re quite small diameter – I use the larger type as rudder linkages in 1OM yachts as they can be curved, if the ends are secured, which gives greater choice of location for the rudder servo. Greased they should be water tightish.

 

Thanks for the interest, I’ll keep you up to date with developments.

 

Kimosubby

 

 

[TelstarParticipant @telstar]

Hi Kimosubby

Am I being too ambitious with size

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=370484110355&ssPageName=STRK:MEWAX:IT

or

http://cgi.ebay.co.uk/Micro-Vibration-Motor-Replacement-Apple-iPhone-4-4G-/300524938056?pt=UK_Mobiles_Accessories_RL&hash=item45f8aea348

 

I’m glad your not proposing modifying lipo’s the lithium in them dosn’t like water so if opened it can go bang

 

I’ll keep watching with interest

Cheers Tom

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Telstar and Ashley

 

thanks for the motor info, have intention to get some buy nows from first reference, they seem small enough!

 

Ashley, nice car, can you do a ford anglia and an air drop LR, my wife used to have one of each.

 

ALSO thanks for the mast tip – spring loading the base for tensioning – I’ve a project where I’m converting a static to water and it has masts that need removing for transport, so hooks on the shrouds and a sleeved mast base with a spring inside should de nicely .

 

Kimosubby.

 

 

[ashley needhamParticipant @ashleyneedham69188]

Kimo. Thanks for that.

 

I had a Ford Anglia 105e for about 18 years. There`s not much I don`t know about them, but I`m not sure it would make a good boat though…

 

Don`t know if the spring loaded mast is a “normal” or “much used” method of tensioning stays, it just came to me. I have not built a sailing boat before. The stays on the Triumph are stainless steel of course, and so will not stretch under tension, but a longer travel but lighter spring would probably be better for natural fibre rigging.

 

Ashley

[Author]

Posts