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Author Topic: Has anyone got a 49" Perkasa with a single Brushless outrunner in?  (Read 382 times)

madwelshman

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Hi guys,

Has anyone got a Perkasa, the 49 1/2" version, running a single brushless outrunner?

If you have, what motor and ESC are fitted?

I have a fibreglass hulled 49" version I'm going to be restoring/rebuilding, that was originally fitted with a 22cc Kawasaki strimmer motor, I want to convert it to brushless power instead.


There are so many different motors out there, I'd just like to know of a set up that works successfully.

I'm not after a rocket ship, but it must be at least capable of scale speed, preferably twice scale speed too. 



Thanks in advance for any info.

Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

Subculture

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #1 on: January 03, 2021, 11:40:44 am »

So you want 11 knots and preferably 22 knots?

Running what size prop 2"/50mm diameter perhaps 1.2-1.4 pitch? So I would look at a motor capable of spinning at about 10-20000RPM and rated around 750-1000watts. A 50mm diameter outrunner around 500-1000KV depending on the voltage you run at.

I would go for a higher voltage set-up at the very least 6S lipo to keep the current in reasonable territory, although at the upper end you could still be pulling 45A, so you'll need very good batteries. Better still would be 12s which would halve the current requirements, and the batteries will have an easier time of it, plus you can use cheaper cells which will make up for the higher cost of the ESC's capable of handling the higher voltage.



madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #2 on: January 03, 2021, 12:17:01 pm »

Thanks for your input Subculture.


I was hoping to stick with 3s or 4s, partly because of cost and I already have a couple.


I do have a 4260 - 500kv, so not as big as the 50mm you have suggested and I appreciate it would only be running at 5500 or 7400 rpm on 3s or 4s. I have a course pitch 50mm prop that I used to run it on with the 22cc petrol motor. Yes the petrol motor revved higher, but it absolutely flew, so maybe those rpm with that prop might be enough.
It's something I intend trying, just out of interest.
The other motor I already have (bought for planes originally) is a 3548 900kv. Again, I was planning on giving it a run, just out of interest.


Thank you again for the advice.
Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

Subculture

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #3 on: January 03, 2021, 12:22:32 pm »

With a 4s set-up and the 4260 motor, I think scale speed is achievable e.g. about 11 knots, but not double scale speed.

The other motor maybe a bit too small IMO.

Bear in mind you can easily series two or more packs up to achieve your final voltage.

madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #4 on: January 03, 2021, 12:32:53 pm »

I was beginning to think that too.
I'm not looking for it to perform like it used to on the petrol, so as long as it will get up on the plane and do at least scale speed, that would be a start.
What I find confusing is seeing people fitting considerably smaller, inrunners to quite large boats, 35"+ with good results, yet a more torquey outrunner motor, swinging quite a bit larger prop doesn't seem as common.
Or maybe I'm just looking in the wrong places.
I don't want a screaming motor, hense wanting to go for an outrunner. I'd ideally like half decent run times too, so trying to keep rpm/voltage down as much as possible, because from what I have read, higher voltage makes for shorter run times, but obviously higher rpm and speed.


Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

Subculture

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #5 on: January 03, 2021, 12:54:05 pm »

'Higher voltage makes for shorter run times.'

No. It's wattage that matters. Watts is voltage x current. 12volts at 2A gives the same watts as 6volts at 4A.

Inrunners versus outrunners- it all depends on the application really. I find there is a lot more choice with outrunners, and they're cheaper and do the job well. I don't tend to go for big stuff though.

I'm afraid you'll have to balance running time with performance.

madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #6 on: January 03, 2021, 12:55:41 pm »

Yeah, in going to have to experiment a fair bit I think.


Thank you.


Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #7 on: January 03, 2021, 01:15:57 pm »

I should add that if you add more voltage to the same motor, it will obviously use more current. Naturally the cheapest set-up is the one you already have. Bigger motors tend to operate a bit more efficiently I find, and with boats you can afford the weight (to a point) unlike aeroplanes where everything needs to be as optimised as possible for best performance.

madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #8 on: January 03, 2021, 01:40:14 pm »

Definitely a bit of trial and error then I think.
I'll give the larger of the two motors that I already have a go and see how it performs.
I may well give the smaller motor a go as well, just out of interest.
I have 5 other boats to restore/rebuild and convert to brushless, I may well be able to use the smaller motor in one of them if it's too small for the Perkasa.


Thank you.
Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #9 on: January 03, 2021, 05:41:16 pm »

It'll pull the prop round, no doubt about that, but expect it to pull some juice on 4s, dropping it to 3s would calm things sown a bit, but it'll still be considerably hotter than the lower revving motor.

madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #10 on: January 03, 2021, 06:12:41 pm »

I have an ammeter, so I can test how much both are pulling with various props and see how they perform on various packs.
I've got a few 3s, a 4s and a 5s 5000 as well, so a few options.

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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

red181

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #11 on: January 14, 2021, 10:32:47 pm »

I did a four foot crashtender, but converted single screw to twin screw, why not do that?


I used 2 x 3 cell lipos wired for 6 cells, actually running one motor, to one esc, to both batts, performance was great, and 5000mah that you have will be fine. You could use that config with a single motor also, you will need more than 3 cells to get anything out of that size hull


these motors where about 20 each, in this pic its two x two cell packs per motor, and it was a heavy ply boats, gps speed was 23mph, well fast enough!


what's that lurking under the spitfire! :embarrassed:
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madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #12 on: January 14, 2021, 11:25:20 pm »

As the Perkasa is already single screw, I would prefer to stick with that, for now at least, the same with the similar sized Huntsman 31 and slightly smaller (42") Huntsman 28 too. Whether I deviate from this and go twin screw in the future, I don't know yet, but I'd like to try with what's already there, but electric rather then petrol/i.c.


The plane under the Spitfire is a Chris Foss Wot4 and to it's left, also buried under there is also my low wing Champion 45s that you can also see the wings from in the picture. There are two profile planes, Saab Draken and an F22.


Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"

mikew

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #13 on: January 15, 2021, 09:02:50 pm »

Hi red181 (Paul)
Reading this with interest but is there a method by which you came to the correct positioning of the twin motor set up?
Mike
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Mike

red181

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #14 on: January 15, 2021, 09:19:31 pm »

thought it was a wot4!


Single screw then, you need something like this,


https://hobbyking.com/en_us/turnigy-t600-brushless-outrunner-for-600-heli-880kv.html?queryID=6da9f5ea43188e658bf327dd03a15c6c&objectID=18629&indexName=hbk_live_magento_en_us_products


52.5mm to 55mm "x" prop, 5mm or 6mm shaft. I got one of these motors second hand, so Ive used it with this set up, on 6 cells (2 x x3 cell 5000mah lipos), Watch out for the amp draw, so start with 50mm and work up,


It needs a decent size propshaft or it will whip and bend, and you need to be able to use  bigger lipos , sub 1000kv motor or as near to that as poss, lower kv gives torque, the high kv motors rev high and are great for race lightweight boats, when built up, and with the lipos, there will be some weight


I've done this, and with gps onboard, I was getting over 20mph, and about 15mins runtime. With a high amp esc you can easily end up spending a lot!
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red181

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #15 on: January 15, 2021, 09:35:46 pm »

Quote
correct positioning of the twin motor set up?
Quote


Hi Mike


Ill try not to take over the thread, but changing from single screw to twin can seem very daunting, but once done, its very satisfying, as it can be more scale, also you then have the option of counter rotation screws which on a faster boat can offset torque roll, or have them same direction  Hope you are ok with this in your thread madwelshman


I made two plywood discs, slightly over the size of my largest size propellers, have a flat on the discs, and rested them on the hull. Attached the props to the discs in the [postilion I wanted them and made holes in the hull where the shafts would enter (scarey bit)


I spent ages getting the shafts straight, and making the angle as shallow as possible, as thsi gives the best propulsion, the prop pushing back, not down. Used a former in the hull to asdd strength, and a ply plate inside the hull where both shafts went, filling the gap with epoxy, anfd thenm made some shaft supports, then just filled the holes where the single screw was. Pictures tell a story better, hope these help!
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mikew

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #16 on: January 15, 2021, 10:18:23 pm »

Thanks for that Paul, and many thanks to Madwelshman for a loan of your topic.
Cheers
Mike
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Mike

madwelshman

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Re: Has anyone got a 49" Perkasa with a single Brushless outrunner in?
« Reply #17 on: January 15, 2021, 10:26:55 pm »

Hi Paul, thanks for the recommendation, much appreciated.


Mike, no problem.


Will
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Precedent Perkasa - 49 1/2"
Precedent Fairey Huntsman 31 - 47"
Veron Fairey Huntsman 28 - 42"
Precedent Fairey Huntsman 31 - 34"
Aerokits Sea Commander 34"
Aerokits Sea Rover - 29 1/2"
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