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Thread: Brushless Wild Cat?

  1. #1
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    Default Brushless Wild Cat?

    I have a 500' body of water really close to me that's small for a fast boat, but fun in the wild cat.

    What I want is to use my standard transmitter/receiver setup...

    ... 5+ more MPH and 20 minutes of run time.

    It's pretty clear that the mounts can be taken out and the motors can be changed and there's room for an ESC, maybe two...

    What I don't know is the Kv of the stock motors and the size?
    What kind of brushless setup would work?

    Much smaller than I've worked with in the past and probably best to ask before tearing in to it. =)
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    Last edited by FighterCat57; 02-14-2011 at 11:13 PM.

  2. #2
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    Still looking for the Kv of the stock motors. They are Aquacraft T270
    Can Diameter: 24mm (0.95")
    Can Length without capacitor and shaft: 30.5mm (1.20")
    Overall length including capacitor and shaft: 57mm (2.25")
    Shaft Length: 10mm (0.40")
    Shaft Diameter: 2mm 0.08")


    I think it could be a fun little boat with twin brushless.


    If I can get enough power out of it, I'll make it my rescue boat!
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    Last edited by FighterCat57; 02-14-2011 at 11:17 PM.

  3. #3
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    OK. Parts ordered! This is going to be a crazy little thing!

    The next question, is prop size. Tiny little guys, anyone know if I can find a counter rotating pair?

    Looks to be an M3 nut. I'm guessing a 1/8th prop will work.
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    Last edited by FighterCat57; 02-14-2011 at 11:52 PM.

  4. #4
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    How about the octura x430 left and right??

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    Quote Originally Posted by forescott View Post
    How about the octura x430 left and right??
    Hmm. I think those would work.

    I did find out that these are 3mm shafts, so again, I think a 1/8th is in tolerance (.17mm)

    I'd really like to stick with plastic and cheap though. I have a set of 32mm counter rotating props that I think would work, however they are for 4mm shaft. I think I can find a 4mm OD, 3mmID tube, but haven't looked yet.
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    Last edited by FighterCat57; 02-14-2011 at 11:54 PM.

  6. #6
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    Quote Originally Posted by FighterCat57 View Post
    Hmm. I think those would work.

    I did find out that these are 3mm shafts, so again, I think a 1/8th is in tolerance (.17mm)

    I'd really like to stick with plastic and cheap though. I have a set of 32mm counter rotating props that I think would work, however they are for 4mm shaft. I think I can find a 4mm OD, 3mmID tube, but haven't looked yet.
    AAAAAH! venom props!

  7. #7
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    Quote Originally Posted by forescott View Post
    AAAAAH! venom props!
    Yep. Cheap $3 props. That reminds me, I have to look up 3-4mm tubing.
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    Last edited by FighterCat57; 02-14-2011 at 11:55 PM.

  8. #8
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    Perhaps a #128 inside of a #129 brass tubing?
    http://www.offshoreelectrics.com/pro...dh-ks-brass-tb
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    Last edited by FighterCat57; 02-14-2011 at 11:55 PM.

  9. #9
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    OK, got the prop thing figured out. Just waiting on Hong Kong Post!

    Have the coupler thing all set as well.

    In case of failure, I have an alternate configuration in mind... HobbyHot has a 60a esc/motor combo with a water cooled inrunner that is very similar in dimensions, but has a larger motor shaft. Looks like it will bolt right up. My biggest worry then would be controlling it. Way too much motor for this little guy. Who knows though, it might make it really fun! It's about $80 bucks though, so will try the bolt in $30 Turnigy solution first.

    My speed/time goal is 30 mph with 15 minutes of run time. Either the Turnigy or the Hobbywing setup will do the trick for sure!
    ________
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    Last edited by FighterCat57; 02-15-2011 at 12:03 AM.

  10. #10
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    care to provide some links of the parts you are using?

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    Quote Originally Posted by turboed13b View Post
    care to provide some links of the parts you are using?
    Sure!

    Plan A:

    2900Kv Inrunner drop in replacement
    http://www.hobbyking.com/hobbyking/s...idProduct=4197

    35-40a ESC for 2900Kv inrunner (2-3s Lipo)
    http://www.hobbyking.com/hobbyking/s...idProduct=6461

    Plan B:

    SwangHobby(HobbyHot) 60a ESC/Water Cooled motor Combo:
    http://www.hobbyhot.com/swanghobby-m...1-pr-2307.html


    I plan on using the 32mm Counter Rotating Venom Propellers with a #128 brass tubing insert to fit as 1/8th props. I'll experiment with both rotating inwards for performance and outwards for stability.
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    Last edited by FighterCat57; 02-15-2011 at 12:05 AM.

  12. #12
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    Ha! Swang's out of the 60a/Inrunner combo! Guess it was a good deal!

  13. #13
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    The drop in HK motors should be here tomorrow!

    Nothing fancy, 2s and little 32mm props to start. The goal isn't massive speed runs, rather a good increase in speed and a nice long run time.

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    The babies are heeeeeeeeeere!

    So tiny!

    Looks like I'll have to shave in a flat spot on the shafts, but otherwise, good to go!

    I'll get some photos of the mounting/installation process. The aluminum cooling coils should fit right on.

    The special instructions on these ESC's say 2s only if over 2000Kv, which I'm at 2900Kv on these lil guys. So, 2s it is. There's room for two 2s 2200kv lipo packs, so will see how the power/run time situation goes.
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    OK, parts in! However, in a 50/50 chance I setup the props spinning outward.

    Hmmm, should I set them up counter rotating in or out?

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    Good question! I thought of reversing the rotation on my ekos to see how it performs.

  17. #17
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    This little mofo is awesome! I may go up to the 36mm props!

    Didn't manage to get any heat out of it messing around on 2s w/32mm props. None, temps in the 80's.

    I left the props counter rotating outwards. This is supposed to help keep the tail planted in the water and will hopefully help with a more forward COG as the motors and ESC's put the COG forward more than I wanted.

    Didn't have time to put it in real water, just the pool, but it literally jumped on plane and launched like a hole shot!

    Don't know if I can get a GPS on it, but I'll try sometime.

    Very cool project!

    Parts list:

    2 x 35a HobbyKing ESC's
    2 x 2445 2900Kv Inrunners
    2 x 32mm Venom 32mm CR Props (Venom Racing 3 Blade Prop D32 P1.4 CR EKOS VNR1982 & D32 P1.4 EKOS VNR1981)
    2 x 2s1p 2200Mah 20c Lipo Cells
    1 x #128 brass tubing to shim the props

    Total upgrade cost including Lipos: $95 plus Rx...
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  18. #18
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    how do you put the esc's into the reciever? real boats have their props rotating outward. are you running two batteries or just using one as an extra?

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    Quote Originally Posted by turboed13b View Post
    how do you put the esc's into the reciever? real boats have their props rotating outward. are you running two batteries or just using one as an extra?
    I used a Y adapter with the red wire pulled on one of the ESC sides. (prevent BEC overlap)

    The battery packs are in parallel, 2s2p 40c 4400Mah total configuration. A full size 150 x 50mm battery would not fit, so I used two smaller format lipos instead.

  20. #20
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    OK, one of you smart guys should have told me that the cables lay in the same direction and switching them to counter rotation, I would need to get a cable laid in the opposite direction!

    I noticed a change in drive sound and quickly pulled the drives, the cable is OK, but I quickly noticed it was laid in the opposite direction as I was using it.

    So, add a new drive cable to the list!

    I think Jeff can make me a pair. His cables are top notch. =)

  21. #21
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    The cables, notice the odd looking one.
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    Approximate measurements:

    3mm hard shaft, 1.2mm cable, 18mm long

    Or... 1/8th & 5/64ths 7 inches long

  23. #23
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    ...or I could just get some .047 music wire, some silver solder and build a set myself... =)

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    will the .098 flex cable work?

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    That's like double the size. The current cable is .047 and the couplers are setup likewise.

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    a lot of people use them in the mini rio's i will check later to see if the tubes are the same size.

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    Quote Originally Posted by turboed13b View Post
    a lot of people use them in the mini rio's i will check later to see if the tubes are the same size.
    I'm pretty sure they will fit in the tubes, they are #128 sized tubing.

    It's the couplers, they would need to be larger to accept the larger wire.

    Although, that's easy to drill out if there's Left/Right or wire drives already available for 3mm (#128) brass stuffing tubes.

  28. #28
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    anything new?

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    Yeah, I got the 047 wire and soldered up a set of drives!

    The only problem is the stock tubing is bent like and "S" and the wires bind up too much.

    I have to make a decision to either scrap the wire drives and go back to the cables without counter rotating props... or... straighten out the brass tubing for a clear shot for the wires.

    Which... I'm most likely to heat up the epoxy and replace the brass with a straighter tube. Since it's #128 brass, I happen to have a couple of pieces of it right here.

    Just time now... My other half is off for a few days, so busy doing other stuff. =)

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