Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Little Rascal]

Can anyone suggest a cheap set up for my first RC boat?

She'll be 23" Loa and 5" beam (584 x 127mm)
She's a fast launch/MTB type built in simple scale from balsa and card.
The original did 40kts.

I need to choose the whole caboodle - single motor, esc, battery pack, prop.

I have a couple of bits I might be able to use: an 'off the shelf' prop/shaft/tube bought from a generic model shop and a small MFA 260 motor on a mount with worm gear.

Specificly I need to know:
What size motor? Would a 260 be enough?
How many cells will I need?
Which ESC?

I'm trying to keep the budget low so any suggestions would be welcome!

Many thanks

Jon

[malcolmfrary]

7.2 volt 380, 6 cell nicad pack, Viper 15.

[cos918]

This is the ESC I use M tronic micro viper

http://www.mtroniks.net/details1.asp/ProductID/185/MicroViper-marine10.htm

Best place to buy them is Howes models Oxford.
http://www.howesmodels.co.uk/RadioControl/viewProduct.php?ProdID=2693

John
Ps I have 4 of them in my models.

[Little Rascal]

Thanks very much guys.

I guess with a 7.2V set up I'd be running at less than 10A then?

I subsequently found Dodgy Geezers thread here: http://www.modelboatmayhem.co.uk/forum/index.php?topic=19215.0

I was impressed with the prices of the ESC's he is using from this site:
http://www.r2hobbies.com/eng/proddetail.php?prod=rcps51601

Obviously they are for planes (no reverse) but at that price I'm tempted!
Anyone forsee any problems?

[cos918]

one problem ,like you said no reverse . go to close to a far bank on a pond cant turn and you don,t have reverse. avoiding collision on ponds no reverse no brake  etc. I would not use it

John

[DickyD]

I'm with John, no reverse is not a good idea.

[malcolmfrary]

Reverse is your brakes.  The ability to back out of a tight corner thats out of reach is a great idea.  The extra cost of the reversing ESC far outweighs the cost of replacing the entire model.
Even though the motor will be pulling less than 10A, with the right (small) prop, it will have scale performance plus a comfortable bit of extra.

[Little Rascal]

Obviously they are for planes (no reverse) but at that price I'm tempted!

Maybe not then!

What about smaller set ups? If the boat was smaller, say 18" x 4"

[barriew]

You could always try this if you really want the cheapest. The last one on this page - the others are for brushless motors - http://www.r2hobbies.com/eng/products.php?cat=160

Don't be fooled by the 110Amps - these are Chinese amps and have been found to be about half UK amps (not literally - but effectively)

You may find these or similar on Ebay which would save on high postage (and possible VAT surcharges) if you buy from China

Barrie

PS The size of ESC is determined by the motor and its power consumption in Amps per hour. The size of the model has some bearing on the size of motor required, but a 20in speed boat needs a different set-up to a 20 in tug!

[cos918]

The size of the boat does not relay come in to it to much. The esc is dependent on the current pull of the motor under max load. Remember the smaller the boat the higher the rpm the prop will have to be as the prop general get smaller. Make sure the esc can  take a good voltage and not max out a 4.8v. I fined  in small boats 4.8v is not enough 6v is better . Then you have weight of the battery to think about . LIPO battery are nice and light but only come in increment of 3.7V so 7.4V is a nice voltage that give the motor a good bit of rpm.Those Mtronics go up 12v  , which will cover most set ups.

John

[Little Rascal]

Thanks for the link - that one works out at just over a tenner with postage.

I realise that it's not just size that counts (planing/displacement etc)
I've looked at various RTR models of this size and type to compare set ups but there's usually little info given or just too many variables.

This isn't your typical speed boat model. She's a high speed WWII launch. She's 64' loa and semi-planing. She doesn't drag her behind around at low speed like a proper planing type and she has a fairly high beam/length ratio (4.5) so I was thinking she'd need less power than an out and out speed boat.

At 40 kts she travels her own length in one second so scale speed is relatively low.

Anyone recommend a source of Nicads? Although I might try 2S lipos to keep the weight down.

I have no idea where to start with propellers size or pitch or revs!

[cos918]

general brass props are better that plastic ones. Give Simon at prop shop a call he is a very knowledgeable person. There props are not cheap  but you are getting the best money can buy.
john

http://www.prop-shop.co.uk/

[sailorboy61]

This is the ESC I use M tronic micro viper

http://www.mtroniks.net/details1.asp/ProductID/185/MicroViper-marine10.htm

Best place to buy them is Howes models Oxford.
http://www.howesmodels.co.uk/RadioControl/viewProduct.php?ProdID=2693


or Mtronics website - demo items...good value, cheaper than Howes on this occasion.
John
Ps I have 4 of them in my models.

[dodgy geezer]

What about smaller set ups? If the boat was smaller, say 18" x 4"

I should point out that I am using these ESCs in boats which are around 12"-18" long, with a typical all-up weight of around 8oz including batteries. The boats don't go incredibly fast, and stop pretty rapidly when you cut the power, so I have never found the lack of reverse to be a great problem. As well as the cost, the other advantage is that they're a fraction of an ounce in weight, and measure 1"x1/2"x1/8". They can be attached directly to the back of a micro motor as if they were a suppressor...

Of course, if your requirement includes maneuverability, delicate speed control, or you have a big, high-speed boat, then these are probably not the ESCs for you. The boats I am fitting them on could be driven at full speed into something and no damage would be incurred by either party...   

[Little Rascal]

Thanks DG. That's the sort of boat I'd like to get into but I think I'm going to start a little bigger so I don't struggle with the weight and available space issues.

I'm now looking at a 22" model with a 380 5 pole motor, Viper 10 or 15 ESC and 6 cell nicad/nimh or 2 cell lipo. I'm estimating that that should kick out up to around 60 watts?

Can anyone recomend a prop? Plastic for price I should think...

Thanks for the input.

Jon