Model Boat Mayhem
Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: CJ on June 06, 2012, 10:44:40 pm
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Evening all,
Well after tinkering to mass expense with my Fairmile, I decided my garage was looking too tidy so impulse bought a Robbe PT15 off e-bay !!
(http://s16.postimage.org/ovm4vji75/039.jpg) (http://postimage.org/image/ovm4vji75/)
Was looking for a partner for my Fairmile so gonna look at a "loose" model of a Vosper MTB - probably the 55th flotilla cos I love the shark teeth !!
Anyway - as you can probably tell from the pics new electrics are needed - so......I would love to get her to plane nicely along, anyone have one or any ideas on what to use
Motor
Battery - I have easy access "free" to SLA but NIMH an or anything else an option
ESC
Propeller size
As always any thoughts appreciated, will try and put a "rennovation" build in warships too !!
Cheers
CJ
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I put a stock 540 from MarksModelBits, a 32 mm 2 blade prop and a 7.2 volt battery pack.
I can get her 3/4 out of the water but on turns she "falls over" and the inside shoulder digs in.
I also have another one which I will fit with 2 of these motors, yes faster, but should be far more stable with 2 props in the water.
Bob
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(http://i124.photobucket.com/albums/p8/DickyD_photos/PT%2015/DSCF2226-Copy.jpg)
(http://i124.photobucket.com/albums/p8/DickyD_photos/The%20Fleet/061-Copy.jpg)
Motor is a Deans Marine Kestral
Battery 9.6v racing pack cross wise behind motor.
35mm 2 blade prop.
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Wow, thanks for the pics Richard, yeah looking real nice :-))
Not sure I want to tip her over Bob !! {:-{ hope nothing too disastrous ?
Richard I can't find the kestrel ? Is it bigger or smaller than the 540 ?
Cheers Gents
CJ
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Kestral motor. http://www.deansmarine.co.uk/shop/product_info.php/cPath/5_13/products_id/200
Forgot to mention, I watercooled mine, simple enough job. :-))
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Thanks for that Richard,
Is she watercooled cos you "need" to - does she run that hot ? Also what ESC are you using to run that ?
Cheers
CJ
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Has anyone tried with 12v SLA at all ?? {:-{
CJ
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A 'lead acid' battery may be a bit heavy for the PT-15.....
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Has anyone tried with 12v SLA at all ?? {:-{
CJ
SLA much to heavy CJ
Mtronics Viper 20 Esc
Warmish motor, thought better to be safe than sorry.
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Thank you both,
I did think that this would be too heavy but was canvassing for opinions and experience, will go with Richard's suggestion and run up a 9600 then.
Will let you know how she gets on :D
Cheers
CJ
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Richard,
Sorry :embarrassed: - where do you get your batteries from, I've just had a look around my local shops and everyone looks wierd at me %%
A link would be great please !!
CJ
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CJ loads of us use The Component Shop.
Excellent prices for goods and P&P
Excellent service, often next day delivery if ordered early enough.
They also do chargers etc.
http://www.component-shop.co.uk/html/large_packs.html
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I put a stock 540 from MarksModelBits, a 32 mm 2 blade prop and a 7.2 volt battery pack.
I can get her 3/4 out of the water but on turns she "falls over" and the inside shoulder digs in.
I also have another one which I will fit with 2 of these motors, yes faster, but should be far more stable with 2 props in the water.
Bob
you MAY be able to get 3 motors in there, full size one is a tripple screw i think
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Thanks for that Richard, those prices certainly are impressive - will be placing an order tmrw so thank you :-))
Ghost - sounds impressive but not sure my pilots license allows low flying boats locally :}
Also not sure I can get 3 in there plus my hands to do any work !! {-)
CJ
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Hi CJ, my PT15 runs off a car fan motor with a 3 blade 35mm prop and a 8.4v NiMh it probably planes to much
I was thinking of weighing the front down a bit so she turns safer at full speed.
Will post some photo,s After sailing her Sunday. Weather permitting. {:-{
john
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Hi CJ.
what size is the voltage of the geared motor you have in the hull at the moment. Can`t make it out but is it a robbe speed motor. ??
cheers Frank
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John,
Cheers for that, yeah would love to see a pic - fingers crossed weather allows you, weather permitting !!
Frank, yeah it is a Robbe 600....also had a Graupner in the box - will bench test them and see if they work at all, but really want her to get her out the water so happy to spend the money and get it right :-))
Why did you want it if it works ??
CJ
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Hi CJ.Many thanks for the p/m. If i can find the picture of mine i will send it to you via e/mail.
Stan :-)) :-)) :-)) :-)) :-))
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Hi CJ.
Ok I would take the geared end off the motor and make it direct drive. The motor is rated for up to 9.6v which is what you will run it on. I run a 36in perkassa on a pair on 9.6v
packs joined together to increase amps / running time. The motor is a 9.6v BB turbo and it planes. I have upped a pix of the harness I put together to join the packs and the boat on
the plane. The prop is a 50mm X racing prop. You could do the same on yours make it fly. Single motor is all you need.
cheers Frank.
(http://s14.postimage.org/ipg1nah65/S5000170.jpg) (http://postimage.org/image/ipg1nah65/)
(http://s17.postimage.org/t09kdobaz/S5000046.jpg) (http://postimage.org/image/t09kdobaz/)
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Thanks again Stan, yeah would love to see a pic :-))
Frank, thank you for the info...funny enough the 50mm X racing prop seems to be the recommended from the messages here and the p/m's too.
Yes I am going to rip the geared motor and I have a deans marine kestrel en route based on the majority vote, again 9.6v battery back on its way too based on what is recommended. :}
Interesting though that you recommend two batteries, thanks for the pic I may set it up to try....out of interest where have you got those both placed in your perkasa ?
Cheers
CJ
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CJ I had a larger prop on mine to start with, kept blowing fuses and not enough speed.
2 blade smaller prop far better and more speed.
Quite often smaller 2 blade prop will give more speed than 3 blade larger prop. :-))
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%% Richard is yours a standard 2 blade, X or S ....may try both see which one gets her airborne :-))
Cheers
CJ
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CJ,
If she is too fast you will get the symptoms of mine.
On turns she will fall away and the front shoulder will dig in.
You need a bit of hull in the water to give her stability.
Bob
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Thanks Bob, yeah I'm somewhere between planing and airborne....think as I've got the motor and battery set en route they seem to make sense, will try a few props and see with trial and error what happens :-))
Cheers
CJ
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If you want her fast trim tabs on the transom would keep the bow down a little so more of the hull in the water.
Bob
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%% Richard is yours a standard 2 blade, X or S ....may try both see which one gets her airborne :-))
Cheers
CJ
Very fine set 2 blade CJ
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Hi CJ.
RE: Interesting though that you recommend two batteries, thanks for the pic I may set it up to try....out of interest where have you got those both placed in your perkasa ?
Here either side of the hull so its balanced... The old school of thought was keep the model light and the weight aft so the nose lifts easily. Your PT fittings are plastic so there`s no
added top -weight. There is no additional ballast in the perky whatsoever yet it sits on its WL.
pic 1 showing rest of wiring, pic2 the packs in situ either side of hull, pic 3 an overview of battery position
(http://s13.postimage.org/ti8hfmjxf/S5000171.jpg) (http://postimage.org/image/ti8hfmjxf/)
(http://s15.postimage.org/twml6sldj/S5000173.jpg) (http://postimage.org/image/twml6sldj/)
(http://s18.postimage.org/55o9vy4x1/S5000176.jpg) (http://postimage.org/image/55o9vy4x1/)
If you want to go planing round the pond for 30mins you need hi capacity batteries.
cheers Frank
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Hi Frank,
Thanks for that, had my single 9.6v pack turn up and have easily modified the tray mount so gonna trial a single pack for now and see how she goes, but yeah I can see two may be quite a simple viable option.
Have posted in the warships builds and rennovations http://www.modelboatmayhem.co.uk/forum/index.php?topic=37569.0 if anyone is interested to see how I get on %%
Thanks as always for all the input :-))
CJ