Model Boat Mayhem
Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: Lancejsy on October 29, 2012, 11:27:03 am
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Hello all. I have always asked any questions on mayhem as I always get good sound advice, Rokbottom wants some advice about a brushless and esc for his Perkasa 48" which will be running on one motor and propshaft. [size=78%]Can you help us with any [/size][size=78%]suggestions on which way to go with this.[/size]
[size=78%]Thank you[/size]
[size=78%]Lance [/size]
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do you want scale speed or ludicrous speed?
Low KV high voltage outrunners (6s 22.2v) seem to be the order of the day with this kind/size of boat
RED181 has a 48" Huntsman running on a single brushless outrunner on 6S lipos
My 36" Huntsman runs an 800Kv Outrunner on 6s.... That has enough power to put the hull almost vertical :o
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Thank you very much for your reply and I will pass it to Rokbottom asap. Once again mayhem members come up with the goods.
Cheers
Lance
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Thanks guys,
I did ask on another post but got no answer.
I would like it to go with a little oomph but not mental as we are restricted speedwise on our lake.
I have some 3cell lipos or I could use a 12v brick as the boat is very light and will need ballast.
Regards,
Len.
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you can link 2 3cell lipos to give a 6cell
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Hi Essex...,
Thanks for that, what ESC goes with that sort of Power, any suggestions of where to buy, I have time as am still licking and sticking the bits back on it.
Len
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Going for higher voltages like a 6s pack reduces the current requirment on the batteries, however not really necessary for sport use, and the esc's tend to be more expensive. I'd go with a motor rated for between 1000-1500kv on 3S lipo.
Andy
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Thanks Andy, and what size ESC?.
Len.
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I would go for a model that can supply 40-50A.
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I would go for a model that can supply 40-50A.
Bear in mind that chinese amps are somewhat smaller than those used in th EU so its best to go for something with at least 30-30% more than you think you need, so I would say go for something in the 70A range.
I have a 200A in my 36" Huntsman. For the extra few quid I think it was worth it
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Well to be honest I'd expect the brushless set-up in such a craft to pull no more than 15-20A e.g. 200W. So I doubled the current rating of the controller. Should be adequate even with Chinese amps, unless you're buying some real rubbish.
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Thanks guys,
I am finding looking through G Cods site confusing as some Boat ESCs dont have reverse!.
Please could you help out a aged numpty by suggesting a suitable setup and Please a link to them, I would be forever in your debt.
Len.
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Do you know the size and pitch of propeller you want to use?
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I can get a 55mm one on in the space.
Len.
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I would say something around 1000KV on 3S lipo would give you a quick boat.
Here's a motor that should do the job easily-
http://www.hobbyking.com/hobbyking/store/__16232__NTM_Prop_Drive_Series_35_48A_1100kv_640w.html (http://www.hobbyking.com/hobbyking/store/__16232__NTM_Prop_Drive_Series_35_48A_1100kv_640w.html)
Forwards only ESC- http://www.hobbyking.com/hobbyking/store/__18462__Birdie_50A_Brushless_ESC_w_3A_BEC.html (http://www.hobbyking.com/hobbyking/store/__18462__Birdie_50A_Brushless_ESC_w_3A_BEC.html)
A reversible controller. Reverse is only really useful as a brake in these kinds of models-
http://www.hobbyking.com/hobbyking/store/__13445__HobbyKing_Brushless_Car_ESC_45A_w_Reverse.html (http://www.hobbyking.com/hobbyking/store/__13445__HobbyKing_Brushless_Car_ESC_45A_w_Reverse.html)
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Thanks Sub,
That ESC with reverse, I couldnt get the video of it to work, is that a fan on it?, is it a plug in and go, or does it need setting up?, sorry about the daft questions mate.
Thanks.
Len.
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I don't know if that controller is plug and play. Usually most controllers benefit from a bit of tweaking, the controller can be supplied with a programming card.
Yes it's a fan on there. It's a car esc, they're a lot cheaper than the marine types. If you want water cooling just run a couple of bits of pipe around the heatsink.
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Bung a 900 motor in it water cool it run on 24v stick packs will last you well over 40 mins using the 55mm prop you have got far cheaper and the same power as the motors suggested
Dave
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Bung a 900 motor in it water cool it run on 24v stick packs will last you well over 40 mins using the 55mm prop you have got far cheaper and the same power as the motors suggested
Dave
But that's not brushless %)
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Wasn't it George Orwell that said "two wires good, three wires better" ? ;D
Richard
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Bung a 900 motor in it, far cheaper
Dave
A 900 with a decent controller is going to rush you what £30-35? The set-up's I linked to are about £25-30.
Few years ago the price differential was high between the two technologies, but not any more.
For sporty/fast running applications, there's no contest between brushed motors and brushless. You have pretty much zero maintenance with a brushless motor, save for a drop of oil on the bearings now and again, they far cleaner electrically, are lighter, more efficient, run cooler and can deliver power outputs that brushed motors can only dream of.
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I don't know if that controller is plug and play. Usually most controllers benefit from a bit of tweaking, the controller can be supplied with a programming card.
Yes it's a fan on there. It's a car esc, they're a lot cheaper than the marine types. If you want water cooling just run a couple of bits of pipe around the heatsink.
How would I use a Programming card?.
Len.
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Programming cards are specific to a series of ESC's so the Turnigy car card wont program the turnigy aquastar series, so first you need the correct card for the ESC, then its as simple as plugging in the ESC to the card and 5 volts (usually from a receiver pack fro example) and either setting a series of jumpers or using a combination of menus accessed through buttons.
Its difficult to provide more specific info due to the many different cards but once you have the card its self explanatory.
Nick
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You can usually program ESC's without a card, by using the transmitter sticks. It's a bit more fiddley though, so people tend to go for the cards.
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Hi
(http://farm9.staticflickr.com/8365/8387395646_22763dd16d_n.jpg) (http://www.flickr.com/photos/len_in_kent/8387395646/)
Vosper Perkasa set up 16.1.13 002 (http://www.flickr.com/photos/len_in_kent/8387395646/) by LEN in Kent (http://www.flickr.com/people/len_in_kent/), on Flickr
(http://farm9.staticflickr.com/8361/8387396314_80154b140f_n.jpg) (http://www.flickr.com/photos/len_in_kent/8387396314/)
Vosper Perkasa set up 16.1.13 003 (http://www.flickr.com/photos/len_in_kent/8387396314/) by LEN in Kent (http://www.flickr.com/people/len_in_kent/), on Flickr
This is how far I have got, I know its not pretty, I did not build it!, I am tarting it up and hoping to surprise a few with its speed.
My questions for you are, as it needs a good bit of ballast I think I will use a Gel Cell Battery, looking at the size of the cable coming out of the ESC, will I be able to use one of the switches shown?. also can I add enough wire to fit the switch in that oblong hole at the bottom of the 1st photo?.
I had thought of using LIPOS, I have some, but Didn't I read somewhere about if you use different length wires you can cause problems?
Thanks,
Len.
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OK I'm curious about what motor you have used, KV size ect, It looks too small for the boat.
Gel batteries are useless for fast boats, I would run it at light trim, remember the full sized boats probably have a foot or more difference in draft from beginning of patrol to end so its not out of scale to have a bit of antifouling exposed.
You can run into problems with longer wire lengths between battery and ESC (and this is regardless of battery chemistry), its safer to run "extended" wire lengths from ESC to motor or alternatively the high power guys run extra input capacitors to solve the issue, unless your extending more than 8-12 inches over the wires already attached to the battery and ESC then there wont be an issue IMO .
The only suitable switch is the largest one but I wouldn't use any switch, use the plug on the battery to isolate power, shouldn't be leaving the batteries in the boat anyway ok2
Cheers
Nick
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Hi Nick,
Its a 3000kv one, I was not planning on leaving the Battery in it, the switch was for isolating the Battery before I lift the boat out of the water.
Regards,
Len.
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You asked for a recommendation above, and you've purchased something completely different. I'm going to assume you know what you're doing.
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You keep asking the questions and ill can read all the answers as they will be use full to me as well bud ;D ;D ;D
Cheers Len :-))
Lance
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Well the first thing you need to bear in mind, is that a 3000 KV motor is going to wind 36000RPM on 12 volts, assuming the battery can supply the necessary juice, which is unlikely from a gel battery. Lipos will supply the required juice provided they're of the correct C rating.
On a 55mm prop, which is probably going to be in the 1-1.4 pitch range, you're looking at over 50mph with 25% slip on the mildest pitch.
Doubtful it'll do that, but the motor will have a good try at trying to, and pull a tremendous amount of amps in the process. I don't think the hardware in the boat looks upto the task, and those chocolate block connectors are likely to be a source of problems.
The 1000-1500KV range I mentioned before was much more suitable for this type of boat, and would have provided ample performance. The motor shown in the install will need to geared down about 2.5-3:1 or run with a smaller prop (less efficient) e.g. 30mm.
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You asked for a recommendation above, and you've purchased something completely different. I'm going to assume you know what you're doing.
Absolutely Not, so how do I get what I have bought to work, sorry I did not follow your suggestions, I got side tracked over availability in the UK store.
I just want the boat to go forwards and in reverse, so do I just add Lipos, I have some Turnigy 3 cell 2200.
I can change the prop,.
Len. <:(
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Very small pack for a boat that size. You'll only get a short running time.
What sort of duration are you after?
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I bought these for a motorised Kite that I made, I have 4 of them.
What sort of duration would I get from one, I do not expect to use full throttle all the time, could I link two together or is that dodgy with lipos.
Thanks
Len.
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I would estimate about 10 minutes on a boat that size, maybe slightly more, or less, depending on what sort of prop you're using.
But that's all immaterial- the motor you have fitted is grossly mismatched for that type of boat- you should follow the link I gave earlier, that shows a motor far better suited.
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you should follow the link I gave earlier, that shows a motor far better suited.
I have one winging its way to me at this moment.
Just what would the one in the boat suit, An Air Boat, A Hovercraft, both of which I am interested in building ( I have built an Airboat ).
Thanks Subculture.
Len.
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You could use it on either of those. You want to run a fairly small prop, a two blade say 5-7" maximum diameter, so as not to bog the motor down.
You'll have to experiment with prop pitch, can't be more specific, as I don't have that motor.
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Thanks for that. I am planning to use the water cooled one as planned, so what sized ESC should I use for the 3000kv job now destined for Airboat or Hovercraft?.
Thanks for your help.
Regards.
Len.
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Don't build a hovercraft mate that's how this forum started, anyway I will be building one soon bud LOL!!
Cheers Len