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Author Topic: Help brushless edf motor in a boat, ?  (Read 3520 times)

dazzle

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Help brushless edf motor in a boat, ?
« on: August 26, 2013, 11:54:57 AM »

Am back to boats for a while as have 4 to finish,  been flying r c panes for 3 years,  though  may give up and sell up planes.

Have just bought an early wood veron/aerokits 35" crash tender, that am going to rebuild/ repair etc
Thinking of powering it with  a brushless inrunner motor and 30 amp controller from my crunched  f-15 eagle edf jet that  run on a 2200mah 12 volt lipo, can use two lipos in  parallel for a longer run time.

A water cooling coil for the motor and also the controller which has aluminum  heatsink would be easy to fit plus motor has a 4 b a ouput thread.
As the motor spun the ducted fan at approx 30,000  plus rpm would it have enough torque without using a gearbox to power the boat ? and what prop size would I need ?

I do not know if above has ever been tried,  If not feasable, could someone suggest a suitable brushless motor for the controller which supplys 30 amps constant I do not know it's peak max amps, I wanted the motor to run at about 20 amps.

Or,  plan b is to do my normal and fit a  glow motor , as am  used to nitro engines in multi boats and planes, only want crash tender up on the plane with some extra speed in hand.

Ta Bob
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Mad_Mike

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Re: Help brushless edf motor in a boat, ?
« Reply #1 on: August 26, 2013, 02:39:03 PM »

whats needed is the kv of the motor, im guessing at 12v at 30k its a 2500kv motor. 30k is too fast for a submerged propeller, thats the surface drive rev range.
Without knowing the size of prop though or what kind of rpm will be needed to get this boat to go i cant really suggest a motor. Hopefully someone will chip and ill fill in the blanks.
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Netleyned

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Re: Help brushless edf motor in a boat, ?
« Reply #2 on: August 26, 2013, 04:05:16 PM »

Glow motor would be OK if your local water allows it.
Fitting a Glow severely restricts the waters available
in the UK.

Ned
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spearfish99

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Re: Help brushless edf motor in a boat, ?
« Reply #3 on: August 26, 2013, 06:20:40 PM »

Hi Dazzle,
 I have a 35" Crash Tender to renovate , bought unfinished off of Ebay.  I was stuck for a motor combination and looked around the forum on the model fireboats web site for some help.
The consensus seemed to be to use a brushless outrunner of about 1100kv and the one linked below was recommended.
  http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=35192
   This should work with your 30A ESC and can easily be mounted on a watercooled mount like this.
 https://astecmodels.co.uk/catalog/product_info.php?products_id=182&osCsid=3f920cd51554b75bfaff19e57d753a01
 While it is meant to be an aircraft motor, it works very well in this mode and being an outrunner has bags of torque for a boat prop. Using 4s lipos , you get just over 16000 rpm and the users on the web site reckon that a 35mm prop ( try 2 or 3 blade) is just right for the small tender
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dazzle

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Re: Help brushless edf motor in a boat, ?
« Reply #4 on: August 26, 2013, 10:20:14 PM »

Thanks guys for your help,

And thanks ever so much spearfish99,  am going to get the turnigy outrunner and w/cooled mount you suggested.

The motor sounds  ideal,  I will try a 3cell 2200mah li po  first and if need more power/speed,  noticed  the motor can take a 4 cell 14.8volt  lipo probably needed for its max 22amps rating,  I just happen to have a brand new 3200mah 14.8v 4s lipo was going to use  in t-20 tigershark plane a  replacement for my f-15,  is now bye bye t-20.

Maybe we can keep in touch as to how we are getting on with our crash tender renovations, I wanted to use epoxy resin on inside of hull to waterproof it, but cannot get access to the front 2 compartments, so have been sanding down the outside, am  not going back to bare wood, just until smooth, then will spray halfords primer and top coat, then brush over with marine yacht varnish and hope it don't leak
when leave in the bath for an hour.

Thanks again for your help.


 
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red181

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Re: Help brushless edf motor in a boat, ?
« Reply #5 on: August 27, 2013, 12:01:49 AM »

I have a brushless setup in this hull, and did extensive testing with eagle tree data logging, ..its  a heavy hull, you need the torque, and the linked motor imo is too high revving and no torque, ideal for light planes etc, not really suitable for a heavy ply boat, you wont get the speed (if thats what you want) and or run time, it will be working hard.
if speed is not required, go brushed, 700bb torque will be great, if brushless, I have a turnigy t600 880kv direct drive, 2 x 5000mah lipos (two cell packs), so I can tell you the performance I have, 19mph, 15 mins running flat out, I can up the cells, but would rather have the speed, 40mm 3 blade cleaver prop
be carefull with stated amps on chinese esc's, they are generally well overstated, I use the turnigy 60amp marine, it has water cooling, reasonably easy to set up and is reversing,
these hulls arenotorious for leaking at the front due to knocks etc, cut out a section of the front bulkhead, some tape on the outside to stop the mess, stand it on its nose, pour some resin in, make sure the front deck is solid or it will delaminate in timespoiling your paintwork.
Its a very different ball game planes to boats, particularly submerged props, you need a good c rating on the lipos or they will discharge very quickly, I am sure you will get more advice, this is what works for me! good luck :-))
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Circlip

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Re: Help brushless edf motor in a boat, ?
« Reply #6 on: August 27, 2013, 10:31:04 AM »

A 35" Crash Tender was never on the Veron books, and if Veron, it wood (?) be made from Balsa. Best powerplant for the Aerokits Crash tender was an ED Hunter, 3 1/2cc Diesel.
 
   Regards  Ian.
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Subculture

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Re: Help brushless edf motor in a boat, ?
« Reply #7 on: August 27, 2013, 11:12:33 AM »

You could run a toothed belt drive on your existing combination- quiet and efficient, and will be less expensive than changing motors and ESC's. I would think about 3:1 to give you an unloaded shaft speed of about 10000RPM. I would expect a 40mm prop of 1.4 pitch should to get the boat up and on the plane on 3S lipo.

SHG do a fairly comprehensive toothed belt range at very competitive prices

pompebled

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Re: Help brushless edf motor in a boat, ?
« Reply #8 on: August 27, 2013, 11:13:24 AM »

Hi Dazzle,

I'd read up on Red181' topics regarding this boat and follow his motorsuggestions, the 1100Kv motor that was suggested to you won't cut it.

Regards, Jan.
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spearfish99

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Re: Help brushless edf motor in a boat, ?
« Reply #9 on: August 27, 2013, 05:05:38 PM »

Hi Dazzle,

I'd read up on Red181' topics regarding this boat and follow his motorsuggestions, the 1100Kv motor that was suggested to you won't cut it.

Regards, Jan.
Have I missed something, but I thought RED181's blog was about the bigger and much heavier 46" version?
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red181

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Re: Help brushless edf motor in a boat, ?
« Reply #10 on: August 27, 2013, 09:52:02 PM »

ive got the 3 footer also! :}  Jan knows me from ages ago when the 3 footer was being built/refurbished
 
Circlips right, its aerokits, not Veron
 
Subculture is spot on, I have (only recently removed as I like tinkering) a belt drive gearbox, using a graupner 700bb torque 7.4v motor, on 12v, ran really well, but a bit hot, and a bit heavy. THe brushless setup isnt really any faster, but what you have to understand with my boats, they always end up stupidly over scale speed. I buy the gears from MFA direct, have a look at the website, the difficult bit is choosing the correct belt length. I have detailed this on my Huntsman build, I know different boat, but the belt drive is discussed a lot. I can change the ratio to suit the lake, small lake, faster acceleration, big lake better top speed, ott I know :embarrassed:   Might not be the answer you need, and ther is a wealth of talent on this forum, so my recommendations might not be the best, but they are tested,
Paul
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dazzle

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Re: Help brushless edf motor in a boat, ?
« Reply #11 on: August 28, 2013, 01:29:59 AM »

Have been looking at motors there are hundreds different,  also am even more confused when looking at brushless boat motors, most are watercooled  inrunners approx  3000 - 3900kv, also found my  brushless edf which is 4300kv, all these are high reves, low torque.
did see a low kv turnigy aquastar that needs a 128 amp controller  add on  a couple of lipos  = 200 total or more,  will take all the fun out of my cheap bargain buy.

Paul,  I would love  to have put resin on inside of front of boat,  but as I said I cannot as there are 2 bulkheads in the way, see pics with 2 roes of pins going into the 2  ply formers/ bulkheads, I do not want to use 2 inch hole cutter and make two large holes through the top deck  in it, 
then apply the resin evenly with a brush, smaller holes and a shake of the hull the resin may not cover evenly or go all over the inside, plus you would have to use a large amount in the hope that it did.

Hand sanding paint on outside of hull back to bare wood, is risky, plus too tricky to use electric sander on thin ply skins,
I also do not want to cover outside of hull in fibreglass mat and resin,  I will use epoxy glue on outside around the front where top deck joins hull, as is a weak point on most boat hulls and also epoxy on inside in places I can access.

Ian I did say veron/aerokits, as always get the two mixed up, it is an aerokits 34" one, yep an ed  hunter would make it move, though never did get the hang of the comp lever on an ed bee in fast patrol launch I had,  wow over 50 years  ago time flys,  I did fit a 5cc glow in similar size 35" fibreglass mtb once, result was a very fast right hand circle then it dived to the bottom of  the pond on a crowded bank
holiday, I waded in fully clothed  and recieved a big cheer when I found it,  the main reason want to fit electric this is a very old wood hull, vibration from a glow motor might shake it to bits so my plan b just gone out the window.

All your help guys and any suggestions  is much appreciated,  have  built and had  boats and all types engines,  scale, sail, speed etc ages ago,  but   woodwork, electric motors  and me do not get on,  more used to, see  pic of my last rebuild/renovation, excuse the light reflections making paint look yeuk in places.

I like a bit of extra speed above scale as well  paul,  i e warp factor 10 mr sulu.

Bob











 






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dazzle

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Re: Help brushless edf motor in a boat, ?
« Reply #12 on: August 28, 2013, 01:36:50 AM »

Site did not upload  2 pics of crash tender ?,  will try again.
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red181

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Re: Help brushless edf motor in a boat, ?
« Reply #13 on: August 28, 2013, 07:25:03 AM »

ok I see where you are up to, so, it was hard for me to do this, but my front deck was warping due to water ingress, We cut out  a section of the bulkhead you can see under the rear windows of the wheelhouse with a dremell, then there is another behind it, that was real hard to do, thats how we poured the resin in to seal it up, with masking tape on the outside to stop it coming out it didnt affect the outer side of the hull, if the boat isnt that bad, maybe just use glass cloth and resin (not big heavy halfords stuff, try delux materials) with the plane experience you have I am sure you can do this.
 
Here is a rock solid motor, on direct drive it will go well, I am using this now in my fireboat, with 3 blade 40mm cleaver prop, but a similar size two blade plastic one will work. Its an outrunner, so no need for water cooling, I run 2 x 2 cell 5000mah lipos so 14 something volts, goes very well, without the gearbox, and a turnigy 60amp marine watercooled reversing esc,
 
http://www.hobbyking.co.uk/hobbyking/store/__44019__Turnigy_T600_Brushless_Outrunner_for_600_Heli_880kv_EU_warehouse_.html
 
I just picked up a spare as I intend to use two of these when I refurb my Huntsman and change to twin screw, they do come up on ebay from time to time, so are much cheaper, make sure its the 880kv one or another similar to this, see how much bigger it is?
 
 
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dazzle

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Re: Help brushless edf motor in a boat, ?
« Reply #14 on: August 29, 2013, 01:26:07 AM »

Thanks paul all noted,

I was looking at the wood care posts on mayhem and found one on aliphatic resin, strong and waterproof, so going to hand sand outside of hull as smooth as I can get it, even if theres still some paint left on it, then brush resin on,  then primer and paint.

As regards motor, now have a plan c to try, came across cornwall models who do, rb gearboxes at different ratios, also gears as well at a good price plus gears are easy to change, will also buy 2 of their props a 30mm and a 35mm, as have a 40mm 3 blade that came with the boat, this may or may not work, but will be interesting to find out.

If it does not, then I will buy a hefty speed controller and turnigy motor.

bob

 

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pompebled

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Re: Help brushless edf motor in a boat, ?
« Reply #15 on: August 29, 2013, 04:15:33 PM »

Hi Bob,

Your plan to 'brush on' resin will only add weight and does nothing for structural strength.
If you cover the outside with one or two layers of 80 Gr glasscloth, than the resin would serve a purpose.

Check out my MAS thread for pictures on how to go about glassing a harde chined hull.

Regards, Jan.
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dazzle

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Re: Help brushless edf motor in a boat, ?
« Reply #16 on: August 30, 2013, 04:17:25 AM »

Hi jan 2 layers of fibreglass cloth will add weight as well,

I have said previous I will not put glass fibre over the outside of hull, a wood hull needs to flex, due to tempreture, conditions etc, also after a good few years fibreglass cloth and resin goes brittle and comes away from wood.

I only want to glue and waterproof the hull,  see mayhem,  wood care,  restoring aerokits, where aliphatic resin is mentioned, which seems the best idea so am going with that, as have read nearly all mayhem posts on, painting finishing and care, grp & epoxy, and other forum subjects that were related, by the way I could not find your mas thread.

Anyway thanks to you all for your help.

Also again to you subculture re the motor, am going to get the 3: 1 gearbox.











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red181

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Re: Help brushless edf motor in a boat, ?
« Reply #17 on: August 30, 2013, 12:52:34 PM »

Hi Dazz,
 
jan is right, all my ply hulls are glass clothed, the inside is left untreated, its obviously your choice, but a lightweight cloth from deluxe materials is dirt cheap, you dont have to cover all the hull if you dont want to, just the front, it will sand back fine and will provide years of service. If you werer not painting the hull then I can see your reluctance, but as you are, its well worth reconsidering your decision. When this was first suggested to me on my 3 footer, I really resisted, but was so glad I did it, it wasnt a hard job to do. The wood will still breathe, on the inside. The glass cloth will not go brittle and come away, trust me I have done it!
 
Alphatic resin is a glue, as the wood flexes over time, this will not flex, and will leak again, check out my build thread, there is a section regarding the glass cloth, in the end its up to you, what ever you do best of luck with it :-))
 
http://www.modelboatmayhem.co.uk/forum/index.php/topic,39278.0.html
 
http://www.deluxematerials.com/
 
Paul
 
 
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