12V motor choice

[MzeeParticipant @mzee]

Good day all,

I have a scratch build 1:20 scale RTTL, based on Vic Smeed's drawings. She is single screw driven by a Graupner Speed 900 BB.and X50 prop (the optimal choice after trying a number of sizes and pitches). The model runs well (though the motor gets pretty hot) but does not quite look scale at full ahead. Anyone know if I could get more 'grunt' from a MFA Torpedo 850? Both on 12v and I can't feed more to the Speed 900 as the Viper ESC won't handle more than 12V

BTW, have just returned home from a glorious 4 weeks in England/Wales – thanks for the suntan!

Robin

[MzeeParticipant @mzee]

[Dave MilbournParticipant @davemilbourn48782]

The Speed 900 is the far superior motor but the only way you will get more speed out of it is to increase the voltage. I've had customers using 20 cells on these but your little Mtroniks ESC would melt and the motor should be water-cooled. You'd be better with an ACTion P98 or Microgyros FR40 ESC. More speed always costs more money, I'm afraid.
DM

[Ian GardnerParticipant @iangardner62867]

Bite the bullet and get an esc that will take more voltage is my advice too- been there, done that. With faster boats I will always want to give myself the headroom of higher voltage if it proves necessary. Some pictures would be nice, especially as we have recently had a bit of a VIc Smeed theme.

Funny, I had my St Canute file out today and thought of you- you are the same gent aren't you?

Ian

[ashley needhamParticipant @ashleyneedham69188]

An 850 on this prop would run all day and not get hot. The 900 is a fairly slow revving thing if memory serves, and so an 850 giving (approx) 8000rpm may be a bit better.

BUT not a lot of chaps like the 850.

Ashley

Edited By ashley needham on 27/07/2013 18:46:24

[Dave MilbournParticipant @davemilbourn48782]

The 900 is a fairly slow revving thing if memory serves

Not on 24v, Ashley! Imagine a big Perkasa with just the last 12" of its hull in contact with the water. Speed 900, X55, 20 cells, P98 ESC. Madness!

Dave M

[ashley needhamParticipant @ashleyneedham69188]

Gosh! Ashley

[Dave MilbournParticipant @davemilbourn48782]

**LINK**

Believe………… MMB900 is identical in spec to Speed 900.
Dave M

[MzeeParticipant @mzee]

Posted by Dave Milbourn on 28/07/2013 17:23:41:

**LINK**

Believe………… MMB900 is identical in spec to Speed 900.
Dave M

Impressive

[Author]

Posts