Wheelnut

My Feedback: (81)

I know the motor could handle it but it would shorten the life of the motor. It gets pretty hot on 7.2V. The esc could also probably handle it for a while, but since the esc does not have a voltage output regulator to the servo, I am betting that the servo would burn out quickly. That happened to me on my mini-t. Cheap servo's don't last long anyway I guess.

Stinger9d9

Now that is a possibility. If the wire had a little too much carbon in it, you may have inadvertently hardened it, and made it brittle. I have complete faith in your soldering skills, but bad wire is just that...bad.

If you try that loctite stuff from OSE, it would allow you to assemble a wire drive with no heat at all.

That way, once and for all, you could prove whether an 0.047" wire (completely unaffected by heat) is too weak or not.

Nina Roses Dad

In the mod thread for the Reef Racer (which has the same electrics) I've heard it works great. Even a 2000mah AA 6-cell makes a difference in the RR over the stock pack (in my own experience) though the 2x3 one I have won't fit inside the MR. The motor in the Reef Racer runs cool because it has a cooling coil wrapped around the motor, but the MR doesn't, it just has that plate and a short piece of tubing (even though Aquacraft's website would still have you beleive that "The factory-installed 380 motor features a water-cooling jacket for efficient performance even at high speeds." [&o]

But, those 7 little cells are going to overheat because the motor will draw more current because it's turning the prop faster against the resistance of the water. Runtime will be reduced. I've decided to go with LiPo in my MR and install a cooling coil around the motor's can.

I was thinking about 7 cells or LiPo myself and so I took some amps readings in the bathtub from a Reef Racer just to get an idea of what the difference might be with the extra cell (same electrics, subsuface drive, different prop (the MR is surface drive and I'd have to fool around too much with whether the boat was on plane, how much the prop was submerged and all that BS). On the 6 cell stock pack the draw was about 4.75, on 7 sub-c cells, it was close to 10 (and the ReefRacer wanted to take off like a raped ape). Of course, you'd never fit 7 sub-c cells into either boat, but I was more interested in what the motor might draw and how much more thrust it could deliver rather than explore the limits of what a 2/3A pack could deliver.

So, my next trip to the LHS will be to get a piece of 3/16" tubing so I can make a cooling coil like the one in the RR. When I install that, I'm going to rotate the motor can 90 degrees so the oval-shaped holes next to the brushes are at 12 and 6'oclock so the brushes can run a little cooler (there's no fan in the can but warm air rises and if the holes are at the top & bottom of the can instead of at the sides it can only help). Next comes a bracket (to hold a 2000mah LiPo over the driveline) that I'll attach to the cooling plate on the motor (using the holes that used to hold the little cooling tube). I'll probably put heavier wires on the ESC's battery lead and change over to Deans mini plugs.

I keep thinking that if I go LiPo I might as well go brushless too. Not so much for all-out speed that's going to give me driveline headaches, but for just enough speed to get the boat on plane quickly, and the higher efficiency that's going to give more runtime. So I'm thinking a lower Kv brushless motor on 2C would make the boat more fun for my 7yo daughter and then I could put in a 3C pack and have my fun almost like having 2 boats in 1...

Nina Roses Dad

Dumb question (possibly) but what would be the difference in strength between a carbon steel wire and a stainless steel one?

Wheelnut

My Feedback: (81)

That is a great idea, but $13.75 plus shipping, that is a little high for me. I would rather upgrade the wire and drill the holes out larger.

Wheelnut

My Feedback: (81)

Carbon is stronger, but will rust. But I think for this application, Stainless steel is better because the tensil strengh is better and it is more elastic. So I think Stainless would work better as a prop shaft. But it will be harder to solder. So for this application the loc603 that stinger was talking about would be the easiest way to join the stainless shaft and prop shaft.
For me, I am going to try and make this simple. I like simple I have a stock prop shaft and cable assembly on the way. When it gets here, I am going to pull the cable out and use some larger wire, like .067. I am going to drill out the prop shaft and the coupler and solder the wire in the prop shaft and test it out.

Nina Roses Dad

I'm thinking of ordering up a 7-cell, sticking it in a Reef Racer, and having it surf waves at the beach.

Then I'll try it in the MR (with the water cooling coil) just for the heck of it and let you guys know the runtime

sussur

Hey guys,

I just tested my MR with the the 7 cell batt.. heck... its like on sterionds! the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGBM3&P=0]7 cell[/link] batt will fit the MR in a diagonal position. I ran it for 2mins just easing on the throttle... Then tried giving it a burst max power.. it ran really fast probably 15 - 20% faster and it planes instantly. Although I notice the servo vibrating in the neutral position... anyway I will do some more testing and probably make a batt pack similar setup to the stock one to balance the COG.

Nina Roses Dad

Thanks for that info. Was the runtime a lot shorter than w/the stock pack? After I put in a cooling coil I'm going to try the 7-cell pack in the config. in this photo.

It might work better for the COG and getting on plane and I can put more weight on one side to offset the torque roll I'd have with the extra power due to the extra cell. Maybe the cells will run cooler since they're split up and sitting directly on the bottom of the hull.

Our pond is huge, so you pretty much have the throttle wide open all the time.

Try my diode trick a few posts back and it should help the quivering of the steering servo.

Wheelnut

My Feedback: (81)

Do not use the stock battery with any type of motor upgrades with out upgrading the wires on the pack. Here is what happened when I ran it with my AMMO brushless motor.

Nina Roses Dad

Yeah, they look like 22ga. good for 5 or 6 amps.

I think the pins in the Tamiya connectors are only rated for 8 amps. If you are going to change the battery leads, change those out too[sm=idea.gif]

Wheelnut

My Feedback: (81)

I was running deans. I should have known to change the wires also

Chuck E. Cheese

My Feedback: (2)

why dont you guys set it up with .098 flexshaft and the stock mini rio prop shaft. just unwrap one wind of the flexshaft and solder it on. this way no liner is needed and it keeps the water out. mine runs a ammo 24-45-2900, 30amp esc, .098 flexshaft, 34mm prop and 3 cell lipo. i used a homemade motormount to mount the motor and got 3 wraps of cooling around it. estamated speed in the low 30's (about as fast as a stock super-vee) and runs well. the only adjustments are prop shaft (stinger) down a hair and weight in the center. i recomend using this flexshaft setup in all mini-rio's (even stock). just drill the stock coupler or use a 2.4mm and solder both ends. you will never buy a shaft again.... oh yeah, when running this fast it is necessary to remove one rudder to get less drag and proper ride angle and height.
i have built 2 this was and they work.

PS: deagio, dig the rudders! how much? (you can sell me the ones from the Hawaii boat, i won't tell)

Stinger9d9

Yikes! 3S and a 34mm prop! How much more can you fit inside this little thing?

A cooling coil too! I'd like to see a video of that one running!

Chuck E. Cheese

My Feedback: (2)

this one is just a first try. i am just a backyard builder (actually i live in a tiny apartment with no yard or garage) with a drill and a dremel. i am super scared of water b/c my reciever and esc are each worth more than this boat.... i am planning on building another one that will be alot cleaner. i have a fiegao 380 3800kv to go in my next one. these are just toys we play with after running real fe boats. i figure with a higher kv maybee i can get away with a 2 cell making it lighter and less likley to come apart during high speed crashes. the only problem with my current one is that i keep breaking rudder brackets just from the speed (not hitting anything) and they are on back order. i will most likley fabricate some aluminum rudders and brackets to duplicate the stock set-up. my worry is that this extra stregnth in the rudders just transfers to the hull. as i saw with one of diego's mini-v's the big minicat rudder and strut is too heavy and puts stress on the hull, craking it..

my current one is fast and usually is driven about 1/2 throtle, but smooth water and a little creative use of the throtle and steering and the thing flys. the key to the 3 cell is driving it. the one i built for a friend runs a 2 cell 28-35-2700 ammo with 35mm prop and is verry controable compared to mine.. both of them have real cooling coils and get 5 minute plus run times without overheating.

also for anyone looking to make big improvements to the STOCK mini rio's here are a few simple mods that improve the speed and maintain reliability: the first necessary mod is the flexshaft, anything other than stock works. the bigest cheapest improvement is to use a minicatracingusa 35mm prop from the micro hydro (the motor will not overheat or even get warm). then move the battery as far back as possable. the 2 cell 1250 15c lipo's dont make near as big a difference as a $5 (for 2) prop. also taking one rudder off is a good speed increase, just remember it only turns good when you are on the gas.

Wheelnut

My Feedback: (81)

I went to minicatracing and I hate to say it, but that is not exactly the easiest site to navigate. I did not even see a 35mm prop there.
I am interested in the possibility of upgrading to a .098 flex cable. To spell it out, I am guessing you are saying to drill out the stock prop shaft and then remove one strand of the cable, then solder it into the prop shaft. Also the motor coupler will need to be drilled out for the .098 flex coupler.
Anyone know of anymore sites with a wider choice of 3/16 plastic props in the 31 to 35mm range?

Chuck E. Cheese

My Feedback: (2)

dont drill the stock prop shaft.... just unwind the .098 cable, i think in total i took 8 strands, 1 or 2 layers, about the last 1/2 inch and it fits right in. then solder it and grind or file it to fit into the stock stuffing tube.. once again, no need to drill the prop shaft, just the coupler. minicatracingusa.com and go to "enter site" then "more" bottom of page, then "parts and accessories. 35x36 mm plastic props right there. another alteritave is the plastic octura y434 (i think, small purple plastic ending in 34, this is mm on octura) but minicat's are better

wamf

OSE has the minicat props in 35mm but it say's 3mm not 3/16" He also has the minicat flex cables, which should fit the mini rio tube.
http://www.offshoreelectrics.com/products.php?cat=51

Chuck E. Cheese

My Feedback: (2)

the prop shaft from the micro hydro will not fit, i tried the stock shaft. the only thing that works is the stoock mini rio prop shaft soldered onto a biger flexshaft. also the stock prop is not 3/16, it is 1/8 and 3mm converts to 1.89/16 so the .11/16" difference is not an issue. i have tried these props and shafts straight from a minicat micro hydro and the props work, shafts dont.... ose does have the props and also caries the .098 cable. the only isssue is the stock prop shaft, driveshafts are on backorder and i'm running out of shafts wuick because i keep making shafts for friends. i also actually lost one because my shaft broke due to misalignment at the motor.

i'm looking for help with the rudder. does anyone know of a small, light rudder other than the minicat one. it does not have to be watercooled, just small and light..

Wheelnut

My Feedback: (81)

The only micro rudder I know of is the one from OSE. He now has it listed seperatley.

Could you please explain this a little better
"i also actually lost one because my shaft broke due to misalignment at the motor"
What shaft was that?

Chuck E. Cheese

My Feedback: (2)

well as you can see in the pictures above, i made a motor mount to accomade the 24mm (not the stock size, 28mm) brushless. i had the motor a little higher in the hull and it put excessive presure on the shaft where it went through the stuffing tube. over time the stuffing tube cut into the flexshaft (this is a common problem with misalignment of motors) and weakened the shaft at the point where it entered the stuffing tube. thus, the shaft broke about one inch from the motor and the rest of it fell out. it happened when i hit a leaf in the water under full throtle. the fix to the problem was to bend the stuffing tube angle at the motor end to get a straight alignment with the motor shaft, install a new homemade shaft and i was running in minutes. the reason i didn't bent the stuffing tube originally and let the build go misaligned was that i was scared to bend the stuffing tube because the hull and servo mounting tray are weak and i thought the presure required to bend the tube might crack the hull or the glue that mounts the servo mounting tray covering it. the solution was using the short end of an allen wrench and being carefull (applying presure to the tube and covering tray) to bend the tube.

i already know about the octura mini rudder and it is still to large, both that one and the minicat rudder mounting brackets are to large for the small trandsom on this boat. i think the solution to the problem is going to be either a homemade version of the stock one. this can be pertty simple by bending a small piece of brass and soldering a short section of stuffing tube, then fabricating a rudder of brass and soldering a straight solid round stick (prob 1/8" in size, i/d of stuffing tube and o/d of solid stock). just cut a slot in the rudder and solder the stock, cut to legnth and find a control arm (or make) that fits the round stock. this type of assembly and fabrication is very common with dumas boat kits. the other solution (and my favorite choice) is to have about 10 sets of stock rudder brackets and control arms in your toolbox. i broke the control arm yesterday and ended up using ca glue to repair it, worked fine for another battery, we will see how long it holds up. also i think i can get away with ca'ing the port side bracket to the rudder as well to hold me over untill the control arms are back in stock. i dont mind spending a little cash on the parts, my problem is that they arent available....

suzukiboy

Do you get stainless steel props for the Mini Cats over there?
I brought some Mini Cats 36mm one's here in OZ last week.

nitro evader bx

nice boats guys. i was wondering if there is anyting wrong with this boat stock. what is .098 flexshaft and what do you do with the strand you unwind? thanks

Chuck E. Cheese

My Feedback: (2)

it is a great boat stock, you just have to know what the micro thing is all about. they are not fast, but they are fun. all the mods make them fast and even more fun. the only thing wrong with the stock one is the flexshaft, it falls apart after time. when you unwind 1/2 inch of the .098 you just cut it off.

Chuck E. Cheese

My Feedback: (2)

here are a couple of video's of my brushless. i added a homemade rudder and bracket and also made a new motor mount. this is 11.1v ammo 24-45-2900 with a y534 prop. keep in mind that i really can't run it full throttle. it is alot more controable on a 32mm prop but i dont have video.... i'm pretty sure this is how grim wanted to build this boat. next experiment will probablly be turn fing and trim tabs.
ENJOY



http://www.youtube.com/watch?v=KayiWUPbHQQ
http://www.youtube.com/watch?v=FE0kCCTuDX4