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Author Topic: speedcontroller for a 49"perkasa?  (Read 6476 times)

gyronuts

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speedcontroller for a 49"perkasa?
« on: October 03, 2009, 07:38:53 am »

Hi,
 I have a 49" perkasa pt boat and  recently fitted a torpedo 850 running on a 12V gel cell.
What size speedcontroller should I use with this setup?
Should I use a circuit breaker or fuse and if so what capacity?
thanks. Bill
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FullLeatherJacket

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Re: speedcontroller for a 49"perkasa?
« Reply #1 on: October 03, 2009, 08:50:43 am »

There are plenty around (e.g. ACTion P98, Electronize FR30HX, MTroniks Viper 40A) but ignore that 11A rating on the motor's box; I've seen these things blow a 25A ESC with no bother. Avoid anything in a blue case with a claimed 110A continuous rating - they have a very dodgy reputation! Note that the P98 and FR30HX will work over 12v while the MTroniks is limited to that value.
For what it's worth, I'd not recommend using a lead-acid battery in a performance boat. It's too heavy and probably won't be able to deliver the current you'd need for a reasonable performance. Use 4.6AH or 9AH NiMH cells instead, and put a 30A fuse in the positive line between battery and ESC.
The MMB900 is a far superior motor and draws much less current - it also fits the same mount as a Torpid 850.
Suit yourself.
FLJ
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barryfoote

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Re: speedcontroller for a 49"perkasa?
« Reply #2 on: October 03, 2009, 09:01:28 am »

gyronuts,

look no further than ACTion. Thney do exactly what they claim. Superb equipment. :-) :-)

http://www.action-electronics.co.uk/

I, like many others am just a happy customer...
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das boot

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Re: speedcontroller for a 49"perkasa?
« Reply #3 on: October 03, 2009, 09:16:23 am »

gyronuts,

look no further than ACTion. Thney do exactly what they claim. Superb equipment. :-) :-)

http://www.action-electronics.co.uk/

I, like many others am just a happy customer...


Same as  that Barry...


Rich
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Shipmate60

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Re: speedcontroller for a 49"perkasa?
« Reply #4 on: October 03, 2009, 10:14:21 am »

gyronuts,
And I would consider changing the motor to a MMB 900.
There is a video on the website showing what 1 of these motors can do in a 49 inch Perkassa.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=19623.0

Mark is a member on here too.

Bob
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #5 on: October 03, 2009, 11:21:04 am »

thanks guys. Having bought the 850 I really need to persevere with it so next question is what size and diameter prop do you all recommend. It presently has a x50 but 2" diameter. Suspect it a bit big? Bill
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Shipmate60

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Re: speedcontroller for a 49"perkasa?
« Reply #6 on: October 03, 2009, 11:40:22 am »

I have to agree with FLJ, the gell cell will be to heavy for her on a single motor.
Unfortunately there are lots of the large Perkassa's that dont perform very well.
They are a big heavy boat to get moving so weight is important.
This means cost, lighter batteries are more expensive, a 12 volt 5 amp gell cell battery will save weight but cut down on run times but still struggle to supply the required current.
850's are quite power hungry so you will need a highly rated ESC.
Sorry, but there just isnt a cheap way to get these large models planing cheaply.
The 850 will take a higher voltage but that would mean a higher rated ESC.

Bob
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Seaspray

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Re: speedcontroller for a 49"perkasa?
« Reply #7 on: October 03, 2009, 11:57:40 am »

gyronuts   What is it wood or fibreglass constrution ?

Seaspray
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #8 on: October 03, 2009, 12:03:45 pm »

its a wooden hull. Having played with electric flight for some years i accept that the boat is to heavy for high performance and I am not looking for spectacular performance as I have a 26" brushless mono hull setup for that , just for it to go a little bit faster than when fitted with the contina fan motor. A club member has a 12v gel cell and an 850 motor and his goes very well. I hope to see him tomorrow to confirm his speedcontroller rating and prop size. thanks for the responses. Bill
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Shipmate60

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Re: speedcontroller for a 49"perkasa?
« Reply #9 on: October 03, 2009, 12:14:48 pm »

What size prop is on the Cortina motor.
These run at about 5000 rpm but with the power available can take quite large props and give reasonable performance.

Bob
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #10 on: October 03, 2009, 12:20:18 pm »

Hi,
   Its a 2"(50mm) x50.
The situation is that I started with the cortina motor on a 12v gel cell which was quite good. Saw my clubmates boat fitted with an 850 on 12v and was impressed. Decide to try upping the voltage with the cortina motor..plan was 16 cell, 18 cell and then 24v if necessary. I had previously hit the prop on a rock and had stripped the plastic universal joint but had glued it back as a temporary measure. Tried 16 cells and the uv stripped again. Thought that changing batteries to get duration and performance was a bit counterproductive so elected to buy and fit the torpedo 850 and accept similar performance that I had observed on my clubmates boat. Bought a new UV and there we are. presently a new 850, 12v gel,new UV,50mm x50 prop and a mktronics 25 amp speedcontroller waiting to sail. Bill
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Seaspray

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Re: speedcontroller for a 49"perkasa?
« Reply #11 on: October 03, 2009, 12:38:04 pm »

gyronuts   I was thinking if you could remove some of the wood from the inner parts frames it might give you less weight and more speed. Big job if the deck is on. Props are a suck it n see job but big slow revving motors don't like to come up against too much torque. They'll eat the gell cell's power.

shipmate60 Got a fiesta fan motor on the KG5 (72inchrs long) and a 2 inch 3 blade prop fitted but its long and thin in the water with a flat bottom. Lasts all day on 12v 7amps

Seaspray
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Klunk

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Re: speedcontroller for a 49"perkasa?
« Reply #12 on: October 03, 2009, 12:51:02 pm »

mine  was a ripmax seasprint esc with water cooling running with 2 x12v 7amp batteries running as 12v 14amp with an 850, this would get on the plane for about 5-7 mins but would quite happily poodle around for 2-3 hours just running at half speed!
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Re: speedcontroller for a 49"perkasa?
« Reply #13 on: October 03, 2009, 12:54:54 pm »

I certainly wouldn't go much bigger than 55mm, so you wont gain a lot.
The MFA 850 on 12 volts will run free at about 9000 rpm and on your load at about 7500 so no great gains.

Bob
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #14 on: October 03, 2009, 02:03:47 pm »

SEASPRAY
I think that the simple way for me to reduce weight is to remove the 12v 7ah gel battery and fit my 3s 3700 lipo pack or even both packs such that it gives 3s 7400.
KLUNK
your setup seems ideal. Any idea how many amps the motor is drawing at high power?

Thanks for the comments/advice.
I have fitted a fuse holder and have some 25 and 30 amps fuses so will see what happens sunday.
Bill
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Re: speedcontroller for a 49"perkasa?
« Reply #15 on: October 03, 2009, 02:22:16 pm »

Slow blow fuses I hope.

FullLeatherJacket

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Re: speedcontroller for a 49"perkasa?
« Reply #16 on: October 03, 2009, 03:00:31 pm »

I think that the simple way for me to reduce weight is to remove the 12v 7ah gel battery and fit my 3s 3700 lipo pack or even both packs such that it gives 3s 7400.

Not advisable to use LiPo cells without a voltage monitor/auto cut-off. None of the speed controllers suggested above has this essential feature. Without it you risk discharging the batteries to below their critical level - then they will likely do a very passable impersonation of napalm. In any event you shouldn't connect LiPo packs in parallel; there's more than just the maths to consider.

Ten 4.6AH Sub-C sized NiMH cells would be my choice. When the speed drops off then replace with a fresh pack and stick the flat one on to fast-charge. Simple and safe.

You have been warned!!

FLJ
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Seaspray

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Re: speedcontroller for a 49"perkasa?
« Reply #17 on: October 03, 2009, 03:01:08 pm »

If you've got lipo packs thats one way to go as the gels can be heavy, I us them for ballast at times.

Not knowing much about the lipo batteries. Would that mean you would have to change the motor, chargers, ESC etc,etc. to accommodate these lipos.

I would prefer the old Ni-cads or Ni-MH


Seaspray
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Klunk

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Re: speedcontroller for a 49"perkasa?
« Reply #18 on: October 03, 2009, 06:40:30 pm »

mine blew a 50 amp esc so thats why i got the sea sprint,which I think I read somewhere it took a load of 238amps, but don't quote me. I never had ANY fuses in line and never blew another esc after the first one! It had a 50mm prop, i did some experimenting with different props, but there was not much in it.! I would go with the mmb motor above if you can afford it. \That seems like a good strong motor that piles out the power (SEE youtube).
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Re: speedcontroller for a 49"perkasa?
« Reply #19 on: October 03, 2009, 10:47:42 pm »

you can buy a separate lipo alarm there are plenty of them about just get one that suits the number of cells, they are only about 3.0 each and you need one a pack look on any Helli site or plane boys use them.so you can use ANY speed controller then.

Peter
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #20 on: October 04, 2009, 01:53:40 pm »

right then. Took the model and wattmeter to the pond. Torpedo 850 with a 2" (50mm) x50 prop and a 12v 7ah gel battery gave 147 watts and 14 amps at full power in the water ...but being held stationary so unloaded current probably about 12 amps.
Model performance good so replaced 12v gel battery with a 3s 3700 lipo to reduce the weight and performance much better.
Photos of gel and lipo attached.
Next question... what propellor should I try now? x45...x50...three blader? clearly want to keep amps at full power less than 20.
thanks. bill
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Klunk

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Re: speedcontroller for a 49"perkasa?
« Reply #21 on: October 04, 2009, 02:41:38 pm »

mine had 3 blade 55mm prop, but tried 2 blade 45 and 50 mm.
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Re: speedcontroller for a 49"perkasa?
« Reply #22 on: October 05, 2009, 10:49:07 am »

As was mentioned earlier props sizes and types are trail and error. Looks like the prop is spinning too much in the water if the pictures are of the boat cruising along, and no just open up the throttle  to get up to speed

Seaspray
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gyronuts

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Re: speedcontroller for a 49"perkasa?
« Reply #23 on: October 05, 2009, 04:06:44 pm »

all photos are at full power. Bill
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JAS54

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Re: speedcontroller for a 49"perkasa?
« Reply #24 on: December 05, 2010, 08:07:06 pm »

Hi, just picked up on this subject and I have a recently restored 1960s Aerokits Sea Queen and have fitted tandem MFA850s (one motor did not have enough torque and revs to get it onto the planewith an X50 prop with a 20 in M5 shaft. Using a Tornado 50A speed controller with 30 amp in line fuse. No problem and planes gently - good for two s/hand motors at 10 !
12v 4600 cellpack is best and quicker onto plane than with gel cell





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