Hello, new guy here...could use some help

Hello All!
I have been lurking around here for a few weeks now researching how to convert my old Miss Circus Circus to brushless. I built the boat 25 years ago and put a Picco 80 in it. I never could get it to run right in the water ...lost interest and put it on the shelf. So recently, got it down and gutted it in preparation for new power. It's amazing what can be accomplished with these new brushless motors. I don't plan on racing it, only running it around on a lake in northern WI. It doesn't have to be wicked fast, in fact I would rather keep it under control so I don't trash the hull. 50mph is good
I don't want to step on any toes here, but I have been in contact with Steve about what setup to use and he suggested Leopard 5698 910kv, on 8S with swordfish x+200A
After measuring the tub and the stuffing tube height, I don't think the 5698 will fit without major work. I don't want to keep pestering Steve with questions, I'm sure he is a busy guy, so I thought I would ask the other experts.
In reading posts, I am wondering if a TP4070 would power the hull. Not sure whether 910kv or 1090kv on 8S. I already have the two 4S revo packs. The boat weighs 9lbs without the nitro motor and pipe
The 4070 will fit easily with an off the shelf motor mount too.
Any help would be appreciated
Thanks

Attachment 163655 This is my Dumas Circus Circus. HET Typhoon 840kv on 8s.

Thanks for the info, that is what I am looking for...someone that has done the same conversion.
Looks like you have more room in your hull than the one I built. Will yours plane out from a standstill? Do you know what prop size prop you are running? Have any idea the top speed you get?
Thanks
This is what I am working withAttachment 163665

TP4070/10D on 10s. I don't know anybody that's run this personally but I do know a guy that has one with plans to test it. If you really want to do 8s for convenience sake I would try the 4y. 10s was the norm for an 1/8 scale until NAMBA changed it's rules.

If you intend to race it anywhere it's worth looking into what those potential venue are running etc. NAMBA is 8s with a list of 3 legal motors and 57mm maximum prop diameter. IMPBA is 10s with a different list of 3 motors. No other limitation. IMPBA does have an allowance for some trial motors. Both of those 4070's and the HET would fit the trial set.

A boat built for NAMBA racing would likely be allowed at an IMPBA event under the trial set. A boat built for IMPBA can only race IMPBA. NAMBA has no place for IMPBA boats today. Unless they happen to be 8s and have the listed motor.

By the book the 4070 isn't legal for either organization. Accept that it IS allowed by the IMPBA trial set.

If yer not race'n who gives rats behind! Don't get any of these. Try TP5670/4Y on 8s and hang on to yer butt.

I've been reading about the rule changes and every ones thoughts. Doesn't sound like people are fans of the new rules. I don't plan on racing it, just running it around on a lake up north, I have a vee bottom nitro boat also.
I like the idea of a large format motor, but the problem is, it won't fit without major work....I was trying to avoid messing with the original setup.

If you're not concerned about racing it you might even consider a Leopard motor.

My affinity to the 56mm TP motors is that they are 6 pole. Little better torque. Big rotor. More mass.

The scale rule set debate is lengthy and varied.

You should be able to get a 40mm motor to push that. The lower kv on 8s will give you larger diameter options on props before you start heating things up but they might not be as fast. You don't want it to be a dog but if you're just looking to have fun with it maybe all out top speed isn't really the goal. Look cool at speed and fun to run.

Thanks for your help. I will probably try a TP4070, just not sure whether 910 or 1090KV is better suited.

Try the speed calculator on the OSE website. I use the last calculator on the page. You can learn a lot about setups(motors and batteries) and props on different hulls without spending any money.

Here's the link...

https://www.offshoreelectrics.com/conversion.php

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A few tips I learned using the calculator are...

- For Prop Pitch Ratio enter the pitch in inches
- Leave the volts per cell at 3.7 nominal
- Be sure to fill in the recommended hull slippage
- Prop diameter is in millimeters
- If anything is off, it's motor efficiency. Manufacturers claims are slightly exaggerated...

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A ratio can't be in inches. It's a ratio.

Quote:

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Originally Posted by T.S.Davis

A ratio can't be in inches. It's a ratio.

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You are right.

I was trying to point out you don't use "pitch" or "total pitch". That's in inches. I know how to get the number I need, I just didn't think thru what I said.

So pitch divided by diameter is the number for that box. And it's a ratio. Enter "prop pitch ratio" the box says.

Prather only gives pitch and diameter for their props.

And some prop manufacturers only give diameter and ratio. Like ABC props.

And they say... Availible in three different pitches
1.4, 1.6 or 1.8 Pitch Ratio

Available in three different "pitches". Then they call it a ratio.

It can confuse the newcomer...

Did I get it right?



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1.6 Pitch Ratio

EX- octura 645 - 45mm X 1.6 P= 72mm of travel per revolution with out slippage.

EX - 4516 ABC - 45mm X 1.6 P= 72mm of travel per revolution with out slippage.

EX - GrimRacer L45 - 68 = 45mm X 1.5P = 68mm of travel per revolution with out slippage

Larry

I did see the calculator, but kind of ignored it... I will look into it closer and try to run some different setups. Also thanks for clarifying the prop ratio entry.

Quote:

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Originally Posted by sammyha

A few tips I learned using the calculator are...

- For Prop Pitch Ratio enter the pitch in inches
- Leave the volts per cell at 3.7 nominal
- Be sure to fill in the recommended hull slippage
- Prop diameter is in millimeters
- If anything is off, it's motor efficiency. Manufacturers claims are slightly exaggerated...

Sent from my SM-G950U1 using Tapatalk

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I'm glad you suggested the calculator, I have been playing around with different setups...looks like it will help hone in on what I should be running

I was comfortable enough to buy three props for my virgin rigger using the calculator.

One for starting out on 6s that should put me close to eighty. And two for 8s that should give me mid nineties and 105ish after I trim it and get a feel for driving it.

So yes, that calculator is a nice tool. No way could I figure all that without it...

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