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Thread: Largest Motor/ESC Combo In JAE Mini Sprint

  1. #1
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    Default Largest Motor/ESC Combo In JAE Mini Sprint

    I am looking to find out what the largest physical motor and ESC has been fit inside of a Mini Sprint. I have read a few different places/posts about selecting ESCs to fit when running 3S and how it can be tight. I have a 2845 that I would like to run on 3S, but don't know if it is possible.

    Any info and photos of Mini Sprints with electronics installed is appreciated.

    Thanks,
    Chris

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    A 28/29mm diameter 45mm long motor is the largest that will fit in the stock position without any mods to the hatch, if you make a bubble canopy or move the motor mount back when building you could fit more in.

    I run Castle Ice Lite 50 with extra caps in mine at the moment, but I have tried an Ice Lite 100 for size and it fits too, much bigger than that and it would severely limit your LiPo selection.

    If you planned out the servo, ESC, battery and RX placements, I think you could probably fit a 120A watercooled ESC and 3000mAh LiPo in it. If you want to work it out the space available between the transom and the boom tube is 206mm long, 54mm wide and 32mm high, but the lip is only 39mm wide, so if you want to get extreme smome may have to be built in. The stuffing tube encroaches in this space starting to come up through the floor about half way down and rising to about 11mm. The middle of the hatch angles up from about 30mm forward of the transom and rises to give 9mm extra space over the centre 28mm by the boom tube, there is plenty of space in front of even the longest motors for a RX, but most suitable servos will need an extension lead to reach that far forward. There is room for the servo up front too, if you want to think outside the box with a 350mm+ linkage. If you do take the time to find the most capable parts that can be shoehorned in post the combo and where it goes as I am sure many will want to know.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Thanks for the reply Paul! Do you have photos of yours?

    I may just buy the kit and figure out what I have that will fit in it.

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    I have a few photos




    This is with 28x36 motor, 50A ESC and 1100mAh LiPo (not really enough LiPo)
    Paul Upton-Taylor, Greased Weasel Racing.

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    That is very impressive! Do you have a photo with the hatch removed?

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    No, but I can take one tomorrow.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Here you go.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Here is mine. It's not as pretty as Paul's though. https://forums.offshoreelectrics.com/...p?albumid=1346

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    I would have to disagree, that has to be the neatest interior I have ever seen, and I would bet that your 3 bearing prop stub will have less wobble than my stock no bearing stub has after 4 years.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Quote Originally Posted by NativePaul View Post
    I would have to disagree, that has to be the neatest interior I have ever seen, and I would bet that your 3 bearing prop stub will have less wobble than my stock no bearing stub has after 4 years.
    Thank you Paul. I'm very picky and everything I do reflects it. You can do bearings in the strut also, it's super easy to do. I'm sure you know how to do it, why don't you?

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    I wanted to see if it would work, to start off with, and it did, better than I imagined for the first 2 seasons, by the third it wasn't ideal but not bad enough to bother with and I have not been very active this season and it will not be the boat I am using next season.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Heys guys, thank you for sharing the photos. This is the first time I have ever seen motors all the way to the front of the tub? I'm shocked that the CG works ok with the battery so far back behind the rear after plane of the front sponsons. It must be ok because your carrying some of the battery weight on the rear ski? I'm sure you could not run this configuration without the rear ski?

    Allen
    Last edited by kacordy; 09-07-2015 at 10:46 PM. Reason: Misspelling

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    Paul, what ESC is that and what is the CoG supposed to be on these riggers?

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    SweetAccord, that is a sweet looking setup! Is it common to jot run water cooling on these riggers? I don't see Paul's hooked up either.

    Is mounting these motors so far forward a custom setup? I think the original Mini Sprint that I ran had the motor mount as a bulkhead located more to the rear...

    -Chris

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    Quote Originally Posted by cjs View Post
    SweetAccord, that is a sweet looking setup! Is it common to jot run water cooling on these riggers? I don't see Paul's hooked up either.

    Is mounting these motors so far forward a custom setup? I think the original Mini Sprint that I ran had the motor mount as a bulkhead located more to the rear...

    -Chris
    Thank you. The original design by JAE called for a 50A ESC with no water cooling but I'm using a 60A ESC so it will not need watercooling. It's not worth adding either as there's not a lot of room in the hull and the run times are not long enough to benefit from it. In additon, I don't wish to add additional unecessary weight, but sure you can always add it if so desired. I have two of these riggers, and the first one I built does not have water cooling either and it runs a 50A ESC with a 30mm prop with a 3500 KV Outrunner 2223 5 Turn and the whole system hardly gets warm.

    Actually, if you look again at Paul's pic's his first post, it has water cooling but he apparently removed it later. I'm sure he can tell you why.

    No, these are not custom setups for the motor location, these are stock motor locations as designed by JAE. I'm not familiar with any other version of the JAE Mini Sprint other than the one originally released by zippkits.com, so maybe you have some other type or design or if you bought it second hand it may have been modified previously? Have any pics?
    Last edited by SweetAccord; 09-07-2015 at 10:39 PM.

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    I doubt I have any pics floating around of it, it was a couple months after the kits came out. I thought the batts were in front of the motor, but I could be completely mistaken too, it was a while ago.

    I am going to pick up one of these kits and see what I come up with.

    I appreciate all of the info coming from everyone in this thread.
    -Chris

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    That is a Castle Creations Ice Lite 50 ESC, with 2 added Panasonic extra low ESR 105C capacitors, I have also run a Castle Phoenix 35 modded for watercooling, but upgraded for the datalogging and it doesn't get hot enough to worry about.

    I recently switched motors form my 3000kv Mega 16/15/3 that I use for 5 minute Naviga mini hydro oval racing to the 4400kv 16/15/2 for SAWs, and as I sometimes wreck Orings taking jackets off, and with the limited run time of SAWs I thought I would just disable the water cooling, which was fine, but when I tested the same setup for the new Mini Hydro Sprint class with its 6 lap minute or so runtime it did get uncomfortably hot so I have ordered another jacket for the 2 turn motor, it (or the new boat) will be getting a water cooled motor again.

    Mine was from the first batch of kits and the motor is in the stock location, I have seen the JAE plans and they have it in the same place. I think the instructions call for 60% of the weight on the sponsons and 40% on the ski, I probably weighed it the first time, but just hang it from the turn fin now.

    Don't be so sure, I run my JAE.21FE with the battery right against the servo in the back and no ski.

    Paul Upton-Taylor, Greased Weasel Racing.

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    Do you also have to use a PiStix since it is an aircraft ESC? Did you have to make program changes to accomodate the inrunner motor?

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    No PixStix, I use an aircraft radio as they are cheaper than ground ones for the same features, I don't use reverse on my boats anyway so having the full stick for forward throttle is an advantage over the half to 2/3rds stick you get on a ground set. Castle ESCs are good and will handle almost any motor, but you will have to try different timings on any ESC to see what suits your setup best.
    Paul Upton-Taylor, Greased Weasel Racing.

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    Thanks again for the information.

    -Chris

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    Quote Originally Posted by cjs View Post
    Do you also have to use a PiStix since it is an aircraft ESC? Did you have to make program changes to accomodate the inrunner motor?
    I use a PiStix as I can't use anything but a pistol radio as stick is not as comfortable to use and hold even with a strap for me. I come from a 1/10 car background so pistol comes naturally, others come from aircraft background or just like stick either way, which is all good.

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    Do your super tiny RXs work with Futaba TXs?

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    Paul, I want to try the wire drive. Can you give us more detail on the center strut that is supporting the wire. It appears that the wire is just running through a bronze bushing? I would assume that the water keeps it cool and there is no need for lubrication?

    Thanks, Allen
    Attached Images Attached Images

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    Quote Originally Posted by kacordy View Post
    Paul, I want to try the wire drive. Can you give us more detail on the center strut that is supporting the wire. It appears that the wire is just running through a bronze bushing? I would assume that the water keeps it cool and there is no need for lubrication?

    Thanks, Allen
    X2...

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    Quote Originally Posted by cjs View Post
    Do your super tiny RXs work with Futaba TXs?
    It works with any FM radio. I happen to use it with a Futaba, yes.

  27. #27
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    My super tiiny RX? It's not really super tiny a regular 607 or 617 7 channel full range RX, the sockets are at 90 degrees to the board which often takes up too much space in minis, so I have a couple like this that I have opened up, soldered a couple of short extension leads to pins on the channels I use, masked off the bind button and covered in electronics grade silicone sealant to waterproof, then put back in the case it weighs a bit more than stock, but can fit in places that pins on the side or on the end wont and will run underwater.

    For the wire support I cut a slot in the bottom of the hull and fitted a piece of oak I think it is 1.5mmx7mm, I cut a divot along one end of it,, pushed it through the hull until it hit the wire, backed it off a touch glued it to the hull, removed the wire, cyanoed a 7mm long length of brass stuffing tube into the divot, cut off the oak flush inside the hull, fitted the wire again passing it through the support. I never tried it without the support, maybe it is not needed, but it is 20" if wire with less than 3" of stuffing tube, about 14" would have been unsupported, and it looked like that would be too much to me. Neither that or the stuffing tube touch the wire at rest and thrust is taken at the strut so it shouldn't be touching much if the time under way either, I can see that it does touch at times but hopefully just to bring it back into line when it starts whipping, i do oil it at the start of a race day, but frankly I think the friction would be less than a flex even if I filled it with sand. I thought I would be breaking the little 1.5mm struts pretty regularly and wasn't really expecting the cynano to hold the stuffing tube on at all, I thought I would probably have to solder something together out of brass sheet, but that is the original unbroken wood strut and I have only had to re-glue the brass on once and that was after a buoy strike, there must be virtually no load on it.
    Paul Upton-Taylor, Greased Weasel Racing.

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    No where near your guys setups and am just starting to build this model, already studied the manual and cant wait to get started, just need to make a tub jig.

  29. #29
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    Take the time to make the jig perfect and straight. It will make a big difference in the end. Make it adjustable also. Measure in MM to get it precise.

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    heres what we got so far, some of the steps weren't too clear but fianally figured it out. now comes the sponsons
    Attached Images Attached Images

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