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Ive got a Major Prop Issue

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Old 07-24-2018, 03:34 AM
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joshreynolds777
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Default Ive got a Major Prop Issue

I have a 43" mono converted from gas to electric running a 1/4" shaft. Well, there is NOTHING available the smaller size I need that accommodates a large 1/4" opening. So my 12S rig still gets a little too hot even running on 6S2P. dont get me wrong.. It hauls on 6S, but I really need to run a smaller prop so I can experiment further. I really want to be able to go up on voltage. Is there an adapter or something ? I feel like my only option is to keep boring out the holes larger like i did on the last one. Even still the prop is too big. I think mine is something like a 50mm now. and It seem Is need smaller. running the Swardfish Pro 300A Lite 4-16S I believe. and a TP 1050kv. Esc stays cool, but motor and motor wires are hot!
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Old 07-29-2018, 09:26 AM
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I know nothing about electrics - but Props I know my share. What size prop are you using? there are some quite small 1/4" props - there are also propshafts with a 3/16" stub shaft and 1/4" flex that will open the door to all the 3/16" props.

Could certainly reduce the blade area on a prop you have (de-tongue it some) which will free up the motor. I have done so on gassers to get a prop to hit the right RPM.
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Old 07-30-2018, 01:55 AM
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I did exactly that actually. I ordered and installed a step down shaft. From 1/4" to 3/16". And Ive got MANY props that will fit now. First test I ran tiny plastic 42mm and it ran about like I thought... horrible bottom end, and top end wasn't great. So today I got a real nice looking 50mm aluminum prop on there (nice looking because the prop nut, prop and drive dog all the same exact size and color) and My damn shaft spun out in the coupler. Never had this happen before.. I thought I made that thing about as tight as i could get it. Y'all ever have that issue. I guess I'll take a shot of go go juice and try it again. Im really hoping that 50mm will be the ticket. Although Im a little worried because everything was cool after that short 2 minute run with that 42mm prop except for the motor. I keep forgetting the damn temp gun, but you'd want to take your hand off it after 4-5 seconds. Not good it seems. I can't believe it got that warm with that tiny prop. Debating going down much lower KV. But I feel like i paid a small fortune for the motor thats in there. I could rob a 440KV out of a heli of mine, but then id have to deal with mounting and cooling and all that crap. But and heres another thing.. how much could the water cooling actually be doing to a motor? I mean the heat is generated from inside the thing, and we're running 90 degree water over the very outside skin of the motor. Im not so sure its really doing a damn thing to be honest. I realize this might be like three different topics in one here but oh well. You guys please chime in!
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Old 08-02-2018, 04:18 PM
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Originally Posted by joshreynolds777 View Post
1) I ordered and installed a step down shaft. From 1/4" to 3/16". This is a good thing
2) First test I ran tiny plastic 42mm and it ran about like I thought... horrible bottom end, and top end wasn't great. Your mistake was using a plastic prop. The blades tend to flex, causing some of the issues you noticed
3) So today I got a real nice looking 50mm aluminum prop on there and My damn shaft spun out in the coupler. If it spun out of the engine end, that means you have a serious misalignment or bind someplace.
3) I thought I made that thing about as tight as i could get it. Although Im a little worried because everything was cool after that short 2 minute run with that 42mm prop except for the motor. I keep forgetting the damn temp gun, but you'd want to take your hand off it after 4-5 seconds. You're right, it's hot. Either too much power or too much load. BTW, what size wires are you using from the ESC to the motor?
4) Debating going down much lower KV. But I feel like i paid a small fortune for the motor thats in there. In our 1/8th scale hydroplanes, we run a NEU 1527 1.5Y 850KV with Octura 457/1457 sized props at 8S between 30 and 65C. Since our boats are similar in size, I doubt it's a KV issue. In fact, if you're running a 42 sized prop on it and the motor is getting hot, that says it's not the prop size unless it's over-speeding the motor
5) How much could the water cooling actually be doing to a motor? I mean the heat is generated from inside the thing, and we're running 90 degree water over the very outside skin of the motor. I'm not so sure its really doing a damn thing to be honest. Actually it is. Even with the water at 90, if you're burning your hands in less than 5 seconds, the motor is considerably hotter than 90. Unless you are using the same size water lines as you were with the gas engine, you might want to increase the size of the lines to increase the amount of water going to the electronics
I'm not an electrical wizard either but I broke down your post and put my thoughts after your comments/questions

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Old 08-02-2018, 11:35 PM
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Wow Thank you very much for that Hydro Junkie. That probably took some time indeed ! Love what you said. I thought Id respond som e and add some thought.

on the plastic yah, i agree, I've been told to start plastic because they're cheap to get the size then go metal, so I've got a good bit gathered. really its hard to imagine the blades bending when I can't even get them to bend at all for me... there sharp as hell too ! any who,,,

The coupler, I got it tightened, should be good to go now ! It was loose off the shaft end... I just didn't get it tight enough .

Now the wires from the motor to the ESC.... this I really think Is an issue.... The guy that build my boat just soldered the wires,, and they get very hot.. meting in fact in some areas. I want to say after a very short run once before even the motor heated up those wires were hot hot. I think something needs to be done about that for sure. They are thin where the two wires were joined. I dont know what size the wires are, they came with the motor and esc.

Th4 water lines are all large.. larger than whats in my DF29. and they're double set.. one to the motor and one to esc.

I was really hoping to throw that 440Kv in there for a true 12s Machine, but the heli I have that motor in sold on me last night.
So I guess Its back to tampering with this thing.

I do have a set of 5S packs Im gonna try Im hoping might be the ticket on that 50mm prop and some better soldering.
Im going to redo it all anyway so i can switch things over to my eC5 connectors the rest of my lipos are on.

So what motors are people running 12S on? I dont see a whole lot of them on youtube it seems. Ive seen some 600kv and 800 some odd thats about it.



This might be a silly question.... but is a boat getting more power running 6S2p (which is (2) 6S packs in parallel right?) than a single 6S? Its got to be right ?
Otherwise more people would be running single packs... Ive just never tested it I guess.
Run tim eI know is the parallel advantage... but Not too worried bout run time, Im used to most of what I have only running for 5 minutes anyway
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Old 08-03-2018, 05:28 AM
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Not a silly question at all.
Think of twin packs as twin fuel tanks. Both have in internal fuel pump so pressure isn't an issue.
In a parallel system, both tanks have been connected to the motor by the ESC. Think of it as a throttle body in a fuel injected engine. Since both tanks have the same pressure going to the throttle body, they both push the same amount of fuel and any excess goes back to the appropriate tank. The effect is that you double your run time while keeping your pressure(AKA voltage) roughly the same through out the run.
In a series system, this all changes. You have one tank force feeding the second. The fuel then goes to the throttle at double the pressure, with all excess fuel returning to the first tank. The effect is like installing fuel injectors with larger nozzles, more fuel goes to the motor so you have more power and only one tank worth of run time. The issue with running packs in series is the higher voltage increases the heat generated and wears out ESCs and motors faster.
Hope this all makes sense
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Old 08-03-2018, 06:07 AM
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yeppers! Good explanation ! so the answer is NO !? correct ? not more power. Got it. For me, since run time has never been an issue. Really Ive been running all my parallel runs for no reason then. ...... But.... Maybe eI am because for Proper CG I really need equal weight about mid engine, and can't get that using one lipo.

Anyway. Im about to have two Zonda Cats show up.. so I'll be distracted with those a years prob. lol. I'll get back on the mono soon enough. Hopefully the 1090kv will work fine on 10S. I hope.. or a small meal prop on 12. cause I really want more juice than 8S !! lol I want a ******* out of Hell ruthless lake water thrasher
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