Brushless motor suggestions

[Empire ParkstoneParticipant @empireparkstone]

[Empire ParkstoneParticipant @empireparkstone]

can anyone advise as to which brushless motor might be suitable for a 1/24 S-boot.. I am aiming to run on just one motor . Have asked on the Other forum but the motor suggested Turnigy 3648 Brushless Motor 1450kv is no longer available other than in HobbyKing Oz and they do not ship to the UK.

[Dave MilbournParticipant @davemilbourn48782]

That sounds like Harry "Canabus" Smith's favourite beast. He is not noted for under-powering his models, to put it mildly. How big is the model, bearing in mind that the motor suggested puts out over 2 BHP?

Dave M

[Empire ParkstoneParticipant @empireparkstone]

Thanks Dave she is 57'' and at present on 3x mfa 850 45mm Raobesch Props Top speed is probably about scale but has to be flat out and run time about 15mins 2x3s 5500 and no it was not Harry but the Guy runs the same boat on the suggested motor.Not to mention he was the only one to reply

[ashley needhamParticipant @ashleyneedham69188]

Really this is just guesswork. Unless you find someone who has a boat the same and his/her setup produces the desired results you can only guesstimate what you might need.

​Replacing the 850`s might be the way to go perhaps with brushless equivalents, albeit of a bit more power.

​Kv to reproduce or better the theoretical 9000 rpm (ish, loaded) on 3s, and of a rating to up the power a bit. The lesser weight and better efficiency should make a difference.

​I am not suggesting that this may be suitable. but for instance a 1300Kv Fusion 3529/10 motor on perhaps smaller props would give a reasonable rev and power increase without going over the top.

Ashley

[Dave MilbournParticipant @davemilbourn48782]

I have a great respect for the Leopard range of brushless motors; they are beautifully made and very smooth running. I have three of them. This one would probably be a suitable choice for your S-Boat if you use at least a 5S pack (18.5v). **LINK** Remove the ali airscrew driver and use the plain 6mm shaft at the other end of the motor for coupling to the prop shaft. For advice about a suitable prop contact Simon Higgins at Protean Design – he used to be "Prop Shop". I'd imagine something along the lines of a 50mm 3-blade fast scale type. PM me with your regular E-Mail address for Simon's details if required.
BTW leaving two props to freewheel adds nothing but drag, and you can't see them when the model is on the water anyway.

Dave M

Edited By Dave Milbourn on 20/03/2017 09:57:00

[Empire ParkstoneParticipant @empireparkstone]

Thanks Ashley and Dave I am hopefully going to get the Turnigy one in my link from OZ and that is proven in the same scale boat Dave I will come back If the Prop situation arises I dealt with Simon a while back when he was Prop shop good man to deal with

Thanks again

[Mark Jarvis 2Participant @markjarvis2]

Have a look at Airtec, they are one of the site sponsors, there range of motors is very good, plus they are a UK in the flesh modelshop, not many left now!!!

[Dodgy Geezer 1Participant @dodgygeezer1]

Posted by ashley needham on 20/03/2017 09:20:27:

Really this is just guesswork. Unless you find someone who has a boat the same and his/her setup produces the desired results you can only guesstimate what you might need.

……….

Ashley

 

It is hard to provide precise advice for a boat motor unless you have a matching model, because each hull is really an individual case. But brushless motors are a bit easier to deal with, since a brushless seems to be suitable for a much wider range of outputs than its nominal brushed equivalent.

Brushed motor design is severely limited by the commutator. Getting power through a sliding, switching contact is difficult, and keeping the cost down makes it more so. Brushgear is usually designed for a specific voltage, and exceeding that rapidly brings erosion and heating problems.

By contrast, the brushless motor will have a much wider working voltage range, and hence a much wider power output capability. They are heat-limited by the coil wire gauge and the magnet Curie Point – but it is much easier to cool the broad body of a brushless than the contact point of a brush. So you can buy quite a small brushless and get quite a lot of power out of it, just by upping the voltage. It would not be unusual to have the same brushless running at 7.2v, or 18v.

Of course, if you want the most out of a brushless you will have to arrange full cooling services! In practice, it is easier to overspec the motor and not worry about heat at all.

The BIG difference between boats is usually down to the propeller. I have seen startling differences in speed from just changing the prop. In an ideal world, we should keep a wide variety of props available to tune each boat to an optimum, but cost and availability mean that we are lucky if we can have two to compare…

 

Edited By Dodgy Geezer on 21/03/2017 13:45:33

[harry smith 1Participant @harrysmith1]

Thank you Empire for defending me!!!

Gee Dave you put your foot in this one, mate!!!

Dave likes stirring me, but, he is OK!!!

I maybe thought of 3 three 3639-1100kv's (about 12,000 rpm) with three 3S batteries as I did not know boat or prop sizes at the other forum site.

The Larrikin aka Canabus aka Harry Smith.

PS We are testing a 3648-1450 with a 2 blade 40mm prop in a 46" Vosper fire tender, only because I had the motor, ESC, battery and prop in my little store.

[Dave MilbournParticipant @davemilbourn48782]

Harry

DM

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