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Author Topic: 46inch RAF crash tender  (Read 365 times)

Mach1

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46inch RAF crash tender
« on: November 13, 2021, 06:57:39 pm »

I have just obtained a completed model of the 46 inch RAF crash tender which was driven by a single electric motor. I am keen to alter this model to be powered by two electric motors. I already have two spare motors that I would like to install, they are Multiplex Roxy BI Outrunners C42-50-06 Brushless Motors 800KV.  I will also have two speed controllers, ZTW Seal 130A SBEC Marine ESC (2-6 Cells). I would greatly appreciate any members advice about my idea.
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madwelshman

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Re: 46inch RAF crash tender
« Reply #1 on: November 15, 2021, 03:46:53 pm »

Yes, you could use those two and just not run them anywhere near full potential, as I would have thought that will be way more than enough power for that size of model.

In fact, just one of those motors would probably be enough on it's own, let alone two of them.


I would say that a pair of 35mm outrunners of around 1000kv would be somewhere near right for that and can be picked up cheaply enough (Around 18-28 each).


Will



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Mach1

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Re: 46inch RAF crash tender
« Reply #2 on: November 15, 2021, 04:35:22 pm »

Thank you for your advice, and yes it does seem that with two of these motors it will be overpowered.
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Dave_S.

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Re: 46inch RAF crash tender
« Reply #3 on: November 15, 2021, 05:45:46 pm »

I bought a second-hand 46" Crash tender recently, it came fitted with a single brushed motor. I am planning to change that for a brushless 4258 500kv running on 16 NiMH or 6S Lipo. I prefer the NiMH option as I object to paying for expensive Lipos only to have to add ballast.


Once I get my bench back up and running, the engine swap will only take a day or two, so I am hoping to get it on the water before the end of the year.

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Mach1

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Re: 46inch RAF crash tender
« Reply #4 on: November 15, 2021, 06:14:27 pm »

Good luck with your motor swap. I really should have just stuck to one motor rather than two. I will have to go easy on the throttle.
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Dave_S.

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Re: 46inch RAF crash tender
« Reply #5 on: November 15, 2021, 06:18:37 pm »

I'll let you know how it goes with the single outrunner, twin motors are more fun, though. I have a Robbe police boat with two and have them mixed so I can rotate on the spot at low speed and back up to a mooring point - adds to the interest of operating. If I was building the Crash Tender I'd probably use two motors, but the one I bought was a just a quick and easy way to get on the water, so I don't want to do anything too radical to it.
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ChrisF

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Re: 46inch RAF crash tender
« Reply #6 on: November 15, 2021, 06:24:56 pm »

I don't think that two motors will affect top speed much, more the acceleration, so as you say easy on the throttle!

And if your transmitter supports it adjust the throttle for a gentler curve.
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canabus

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Re: 46inch RAF crash tender
« Reply #7 on: November 16, 2021, 05:36:15 am »

Hi All


I am using a Scorpion S4020-450kv (1850Watts) on 6S Lipo (12150rpm) with a 120Amp ESC and a 52mm 2 blade CNC prop.


At 80% throttle scale speed with plenty of power left.


Used twin 3S 4500mah batteries (in series) and mounted each side of the rudder to get the boat to plane and turn right.


Canabus

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Dave_S.

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Re: 46inch RAF crash tender
« Reply #8 on: November 16, 2021, 07:42:40 am »

Very similar to my set-up (not yet installed) - how many amps are you drawing at full throttle with this?


Not quite sure where your revs are coming from, 450 kv on 6s Lipo should be just under 10,000 RPM maximum, less in practice.


(I'll get those Waverider plans sorted out soon!)
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canabus

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Re: 46inch RAF crash tender
« Reply #9 on: November 16, 2021, 10:07:05 am »

Hi Dave
the rpm should be 10150, but just got a new pair of Nanotech Lipo batteries which are 15.2 volts !!!


Canabus
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Circlip

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Re: 46inch RAF crash tender
« Reply #10 on: November 16, 2021, 10:29:17 am »

" I am keen to alter this model to be powered by two electric motors. "

  Why? Is it going to be a shelf queen.  Would be inclined to thrash it about before damaging the hull.

   Regards  Ian.
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Mach1

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Re: 46inch RAF crash tender
« Reply #11 on: November 16, 2021, 12:39:30 pm »

Thank you all for your advice and shared experience with one or two motors.  I am pressing on with my two motor installation and will report on the performance. The throttle curve idea sounds a good plan.
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