Taming my brushless Mini V

[G1ST]

I know many here have "been there done that" but I recently got a brushless Mini V from the swap shop here, It has a 380 size 3100 kv motor, seaking 35 esc and 3s 1000mah batteries. I added a water pickup on the transom just left of the driveshaft to cool the esc. For now I am using the stock outdrive and prop. It also has 3/4"w X 1-1/2"l trim tabs.
When I run it I can't give it any throttle beyond about 1/2. Even at steady 1/2 throttle it has a ton of list to the right. If I crack the throttle at any speed it flips. (clockwise).
I'm gathering parts to go to .098 flex and strut and rudder system.
Any ideas to get me more driveability until I can make the conversion?
I've done a couple of searches but didn't find a magic bullet.
Thanks in advance for the help.
Greg

Sorry for the long post

[tim v]

try 2 cell

[martin]

Do you know what hull it is & what size is it, Is it sub surface drive & what props are you using. Martin.

[martin]

Just realized its a surface drive as you stated you added a water pick up to one side of the shaft. Martin.

[G1ST]

Sorry
It's a Proboat Mini V. About 14".


All I have right now is 3 cell batteries.

Greg

[TomM]

3100 kv is very high. Chances are that could be attributimg to your problems. With mine i have a 2700kv on 3 cell and even then it starts to get a little bit hairy as higher speeds. The .098 flex cable conversion should help because it will give you a greater selection of props to choose from.

[martin]

Sounds like the motor has been replaced with to powerfull motor, Arnt the original fitted with a 3000kv to run on 7.4v. Martin.

[TomM]

Originally it comes with a brushed motor. The stock esc can handle the 7.4v lipo, but the outdrive normally melts the u-joints when you hook up a 3s lipo.

[martin]

A 380 brushless motor on 3s is way to much on this size boat. Martin.

[G1ST]

I figured it was probably way too much motor.
Hopefully I'll get to order a 2 cell battery and some small props when payday rolls around.
Thanks fpr the input
Greg

[G1ST]

3100 kv is very high. Chances are that could be attributimg to your problems. With mine i have a 2700kv on 3 cell and even then it starts to get a little bit hairy as higher speeds. The .098 flex cable conversion should help because it will give you a greater selection of props to choose from.

Tom what prop are you running on yours?
Greg

[TomM]

I run a x430. Temps are very mild. Never has a problem at all, i could prop it up a little bit, but then I'd be risking torque rolling

[G1ST]

I probably should go with a X427 since I have 3100 kv to contend with.
I can always prop up.
I just want to get up into the correct rev range.
Greg

[TomM]

Anything under around 27,000 would be okay. Just watch temperatures and torque roll. Be gentle, its a small boat and requires finess to drive

[G1ST]

Yeah torque roll has been my nemesis with this boat.
It'll all fall in to place.
The fun is in the process.
thanks
Greg

[wparsons]

Make sure the prop is sharpened and balanced well, that will help with torque roll a bit too. You could also shift your battery to the left to help fight it rolling right.

[G1ST]

Today I converted the boat to a .098 flex drive and added an X427 prop.
Saturday will be my first opportunity to test it out. I'll post my results
Greg

[G1ST]

Tried to make a run today but the wind was howling and made fit pretty choppy.
I'll try another day
Greg

[Pete32200]

A steerable outdrive with no u-joint?

[Dustin Sontag]

A steerable outdrive with no u-joint?

Thats what i was just looking at.....

[G1ST]

It has a .098 flex shaft now. No U-Joint at either end.

[679alex]

Anyone got a part list to upgrade to Brushless ?
i got a stock mini-V and i wanna go Brushless ...
Shoul i upgrade or get aquacraft mini mono or Proboat impulse (small one) ?
Thanks for the help in advance =D

[G1ST]

I'm anxiously awaiting the Minimono

Right now in my Mini V I am using a 3100kv 380 sized motor
.098 flex shaft to 1/8 stub shaft
1/8 to .098 motor coupler
X427 prop
All of the above can be purchased here at OSE.
35A Seaking ESC
11.1 volt 1000 mah lipo.
This set up is too much for the mini V hull but it's what I have. Very challenging to drive.
2 cell lipo or lower kv motor would make more sense.
IMO the hull is not really up to high speed brushless use. Too short and narrow. I've flipped it with just the throttle.
I think a hull about 18" would be ideal for the gear I have.
I will say I really have a lot of fun with my Mini V. Certainly not boring.
Hope this helps you
Greg

[679alex]

How much did it cost to build it?
Thanks :biggrin:

[G1ST]

Including the boat (bought here in the swap shop) I'm in it about 125 minus batteries. I was lucky, mine was already set up and had a BL moter and a standard servo. I changed the ESC, added the water cooling and changed to flex drive and smaller prop. The brushless motor with the stock prop had wicked torque roll.

You can do it in stages,
1 Motor and ESC and add the water cooling. +/- 75.00 depending on motor.
2 Flex, coupler and prop. 30.00

Watch the swap shop for used stuff and you may save some dough.
Have fun
Greg

[679alex]

okay but,
Do the stock Tx,Rx can be used ?
Thanks =3

[G1ST]

Unfortunately no
The stock Rx is combined with the brushed ESC. Also the stock servo is 4 wire.

[679alex]

okay :crying:

[G1ST]

Don't be discouraged
Half the fun for me is finding the stuff you need to assemble your project into something unique.
It just doesn't always happen instantly unless you are buying new.
Greg

[679alex]

i will try to use futaba Tx&Rx i found somewhere at 39$ ... Cant remember where but i will find it back or maybe the tactic from aquacraft and use your build :)

[679alex]

Shoul i switch the Mini-V Hull for the Mini-C hull for less torque rolling ?

[G1ST]

i will try to use futaba Tx&Rx i found somewhere at 39$ ... Cant remember where but i will find it back or maybe the tactic from aquacraft and use your build :)
Perfect
You will have a lot of fun. Make sure you ask lots of questions. There are many experts on this forum.

[G1ST]

Shoul i switch the Mini-V Hull for the Mini-C hull for less torque rolling ?
I don't have any experience with the Mini C hull but I'm sure others will chime in.
I will finally get a chance to run mine again Sunday. We are trying a new pond. Our regular pond is overgrown with duckweed. That is some nasty stuff.
I'm hoping that the change to the smaller X427 prop will make the torque roll manageable.
I will report.
Greg

[G1ST]

I did get to run my mini V Sunday. Great fun. I ran 2 packs through it without incident.
It never saw 100% throttle but after a long slow run up to speed I was close. Still had torque roll and I'm sure I could have flipped it if I was careless with the throttle.5638756388

[679alex]

Nice ;)

[679alex]

Look what i found :]

http://www.youtube.com/watch?v=2lsbsIvdWmc&feature=related

Forum link:

http://www.rcuniverse.com/forum/m_6275803/anchors_6277675/mpage_1/key_/anchor/tm.htm#6277675

That mini-V is fast :)

[G1ST]

NICE! I like it. Looks like torque roll isn't much of a problem.

I was thinking of getting a Proboat duck jet drive and playing around with that.

[679alex]

Its fast ^^
Ima try to find these part ... the one from website they say are discontinued ;(

[679alex]

MiniJet :
http://www.v-eastonline.com/products/Mini%252dJet-.html

motor:500-600 Brushed (required)

i dont know if this work :)

[wparsons]

If they're actually in stock, that's the drive you want. It's the same as the NQD Tear Into drive, just the original made by graupner not the cheap knock off. Dimensions are the same, other than the graupner one uses a 3mm shaft instead of a 2mm shaft.

Stick a 28mm brushless motor on it (inrunner or outrunner) and you'll be set. Just aim to keep the rpm's in the 25k range tops since above that the drive loses efficiency.

[679alex]

If they're actually in stock, that's the drive you want. It's the same as the NQD Tear Into drive, just the original made by graupner not the cheap knock off. Dimensions are the same, other than the graupner one uses a 3mm shaft instead of a 2mm shaft.

Stick a 28mm brushless motor on it (inrunner or outrunner) and you'll be set. Just aim to keep the rpm's in the 25k range tops since above that the drive loses efficiency.

21 500 RPM enought ? (speed 600 BB 7.2v)


There a mini-V whit the Proboat Duck jet drive:
http://www.youtube.com/watch?v=z4EQAESJpMM
in a river ... we cant really see the real speed :/

[wparsons]

A jet drive is never going to be as fast as the same power system with a surface drive, but it'll be more maneuverable and accelerate WAY faster.

I would suggest a brushless motor over a speed 600, but that should give you decent thrust as well.

[679alex]

Do the stock mini-V esc can handle the 600 speed ?

[wparsons]

No clue, not sure how many amps the stock ESC can handle at all.

If you run it on the stock electronics with the jet drive, it will likely be slower than stock though. At the very best, I would say it might be the same speed as stock.

[G1ST]

wparsons
Do you think the smaller Duck jet drive is enough for he mini V? I was going to try it with the 380 sized brushless motor.

[wparsons]

I think someone else already tried it? IIRC it was slow on the stock brushed motor but was decent with a brushless motor.

You definitely don't need a 380L for that drive though, you could use a 2040 motor on it just fine, it's a really small impeller.