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Author Topic: Huntsman 28 going from brushed to brushless, advice please!  (Read 7487 times)

red181

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Hi all, here we go again with the brushless mystery! :embarrassed:
I have been reading the great posts from various forum members, and looking at the pics of mrfixit's award winning fairy swordsman at wicksteed and want to convert my 4foot Huntsman 28.

Currently running a graupner 9.6v motor, on two 9.6v 4600 nimh's, with 50mm 2 blade x prop, all through a 2:1 gearbox. Its a heavy old girl, all ply, just put it on the kitchen scales, with graupner motor still fitted and it went off the scale, I guess its 3kg or more.

Now, please please no suggestions regarding other brushed setups, only brushless. The boat was tested last wed, then sunday at New Brighton, I have spent a long time trying various props, ranging from 4 blade cleaver 50mm, all the way back to 35mm x props, and tried 3 different motors, this combo gave the best speed, and an acceptable run time, the bench mark beimng 20 mins, mostly flat out.

So, has anybody got a brushless setup, in a similar hull, anybody got a video of the swordsman at wicksteed running, ???

I have sort of set my mind on a hobbywing 60amp esc, this has water cooling, 120amp burst, and reverse, but the different motors available are mind blowing! I think a high kv motor is all revs, no torque, and low kv is loads of torque, no speed. I would like to keep my gearbox set up as its a perfect drive train without weak couplings, and is belt driven, so I do have the option of changing the gear ratio, even going to 1:1 I suppose, giving direct drive.

It has to be fast, like the lifeboat of Lifeboatpauls (mayhem member), so if you know of a good performing brushless large scale fast electric, please share the info! :-))
If you are not familiar withn this boat, here is a picture so you can see the size I need to push along, its unfinished, I want to get the running gear sorted before all the fittings etc go on



Many thanks
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #1 on: July 01, 2009, 01:35:16 PM »

come on guys!!!! I am itching to get this boat finished, anybody got any ideas???? I spent hours last night looking at youtube videos, but came up with nothing, please help!! :-))
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andyn

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #2 on: July 01, 2009, 06:03:36 PM »

You could get a MEGA or Feigao motor from Astec models, and go very fast...

This would probably be best posted on the 'fast' electric forum, on Astec models' site. I'm not by any means an electric person, but you will probably get better answers there.

I would get one of these for it...
http://www.astecmodels.co.uk/catalog/product_info.php/cPath/24_46_85/products_id/658
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DickyD

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #3 on: July 01, 2009, 06:15:39 PM »

Can someone tell me why people spend ages making a scale model getting everything just right, and then put a motor or motors in it so that it travels at a scale speed of 200 knots ? We have a chap at our club who has Perkasa which does this and although it looks impressive it also looks ridiculous.
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andyn

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #4 on: July 01, 2009, 06:18:19 PM »

I have always said you have a left thumb for a reason...
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DickyD

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #5 on: July 01, 2009, 06:26:20 PM »

Dirty boy !  ok2
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #6 on: July 02, 2009, 12:47:15 AM »

I was thinking of Astec Andy, and someone else has mentioned those motors, its the kv/rpm thing that I dont understand, have you seen anybody with an electric brushless setup with a similar hull? The brushless motors just seems so small! :}

Dicky, dont really know what relevence you post has, but in my case, I want it to work like the real thing, and as you can see, the Huntsman 28 was a seriously fast boat in its day




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Perkasaman2

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #7 on: July 02, 2009, 01:25:25 AM »

Like you, I have trawled the brushless posts but info on here is patchy. I found out more on Wickipedia by simply typing'brushless motors' - the info on types and their characteristics is very well explained and probably sufficient for you to make  a list of featurs etc from which a real contender could be tracked down through a supplier and ensure their offering has your required spec. sufficient to drive your deep v hull/single prop. I am researching for a 2 prop installation for a fast hull, similar length. You are probably a pathfinder on this forum.  :-)
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andyn

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #8 on: July 02, 2009, 10:58:58 AM »

Like you, I have trawled the brushless posts but info on here is patchy.

Don't ever say that around Andrewh, his footy squadron will attack...

Try : http://www.modelboatmayhem.co.uk/forum/index.php?topic=13538.0

Basically the k/v rating is how many revs you get per volt, so at 1100kv, at 11.1 volts, my Shockie's brushless will produce 12,210rpm. At 6200kv, my Feigao will produce 68820rpm also on 11.1 volts. Meanwhile the absolutely lunatic motor I have around here somewhere, which is 9200kv, if I could get a speed controller with oscillations fast enough would produce 102,120rpm on 11.1 volts.

In theory, the lower the kv rating you have, the more torque you have, and anything above about 2500kv is considered a fast or 'hot' motor. But it more depends on the setup you have, the prop you are turning and purely how well you can set up a boat.
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Perkasaman2

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #9 on: July 02, 2009, 12:19:04 PM »

Many thanks for the link andyn  :-)), I  missed this excellent thread completely - apologies to Andrewh.  :embarrassed: (I don't think the forum 'search' facility like's my keyboard.) It's understandable that members are anxious to make the right choices 'going brushless' when you consider the cost. I'm not interested in 'racing' speeds, rather, 'scale' planing with loads of endurance, mind you, the odd 'blast' would be great. %)   
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andrewh

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #10 on: July 02, 2009, 12:58:05 PM »

Paul,

Here goes with the andrewh reply in the usual form:
I don't know the exact answer (which depends to some extent on depth of pocket and whether you want to achieve Fast!  AWESOME :-)) or mental!

The Huntsman - solid, fairly heavy, planing hull.  Not unlike a lifeboat in style  - only single screw and more efficient (lifeboats have to hide their screws from rocks). 

How much power do you need to get satisfactory performance?  My guess is 750W to 1000W transmitted thru a suitable screw
(you presently have a 50mm, 2-blader)
Gearbox - if we had a clean sheet of paper I would strongly suggest  - lose the gearbox.
  Bl motors are best run direct - especially the type we are going to finish up with - the provide STONKING torque. 
If you are going to stay with the box then all the KV figures need to be doubled at the motor - for example if 1000Kv seems to give the right prop performance, with a 2:1 gearbox you will need a 2000KV motor

Way to find an answer: 
Look at the 1/10 lifeboats - se what they are using - especially the props. 
See what Alan suggests  - usually an Overlander motor
Stavros has a single-prop Huntsman with a Turnigy rat-motor in it - I think it runs on 12 or 14 Nimh cells

All these are instructions to myself  more than you
more as I uncover it
andrew
 
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Proteus

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #11 on: July 02, 2009, 01:08:02 PM »

Paul,

Here goes with the andrewh reply in the usual form:
I don't know the exact answer (which depends to some extent on depth of pocket and whether you want to achieve Fast!  AWESOME :-)) or mental!

The Huntsman - solid, fairly heavy, planing hull.  Not unlike a lifeboat in style  - only single screw and more efficient (lifeboats have to hide their screws from rocks). 

How much power do you need to get satisfactory performance?  My guess is 750W to 1000W transmitted thru a suitable screw
(you presently have a 50mm, 2-blader)
Gearbox - if we had a clean sheet of paper I would strongly suggest  - lose the gearbox.
  Bl motors are best run direct - especially the type we are going to finish up with - the provide STONKING torque. 
If you are going to stay with the box then all the KV figures need to be doubled at the motor - for example if 1000Kv seems to give the right prop performance, with a 2:1 gearbox you will need a 2000KV motor

Way to find an answer: 
Look at the 1/10 lifeboats - se what they are using - especially the props. 
See what Alan suggests  - usually an Overlander motor
Stavros has a single-prop Huntsman with a Turnigy rat-motor in it - I think it runs on 12 or 14 Nimh cells

All these are instructions to myself  more than you
more as I uncover it
andrew
 


are there any charts that give an equivalent to brushed   like a 700bbturbo 8.4 and what the brushless would be for the same power and say a 27 turn standard buggy motor  or say a speed 600 or 500 this would help people get an idea for having a dabble in brushless knowing they will prob get a bit longer run time and what would up there speed a bit

thanks for the info up to now.


Proteus
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #12 on: July 02, 2009, 02:39:53 PM »

many thanks for replies:

Andy, makes more sense now, so I took the align 430l 3350kv motor out of my trex 450 heli, it revs its nuts off, but I was almost able to stop the shaft with my fingers, so with what you are saying, high kv, speed, but no torque? so I need a compromise with this big boat, torque to get going, and speed to keep going!

Andrew, thanks for the comparison, so I now know what sort of boat to be looking for, wasnt there a  chap on here that got blistering performance with a large lifeboat sometime ago? I see what you mean re the gearbox, it does however mean no coupling weak joint, so I could modify for 1:1 or change the ratio and drive belt for 1:1, its that flexible. We truied a vast number of props, the only other one that was good was a 3 blade "steamer" design, I think it was 50mm, it was "borrowed" I will have to ask the owner! :embarrassed:

Proteus, great idea if we can compare spec of "known" brushed motors with spec of brushless, it would give us a benchmark,

keep tyhe posts coming guys1
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Martin [Admin]

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #14 on: July 04, 2009, 01:42:00 PM »


""Forward" mode and "Forward/Backward" mode" sometimes doesn't mean it is a "Reversing" ESC.
 I'd confirm that first.

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MRZIPPYXXXX

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #15 on: July 04, 2009, 11:18:54 PM »

Hello,
I am the Wicksteed Swordsman owner, originally she ran with a watercooled 8.4volt Graupner 700BB Turbo on 14x3300nimhs 40mm graupner hydro prop quite fast,
through various sets of cells, eventually 18nimhs very fast (modernday 1.5hp OS 40 glow territory) but lots of heat, brush gear dust everywhere and short run times.

Decided to go brushless with an Overlander Thumper outrunner 4250 600kv motor, initially a huge disappointment slow!
Then met Alan Noble at last years Warwick show, and it was his advice that made all the difference - fit a huge 50mm scale steam prop!
The model was much faster, nearer 700BB speed, but greater efficiency, no heat/smoke etc, longer running times.
Have since changed to a smaller higher revving outrunner 1050kv motor 20 from Giant Cod result more speed and even longer running times.

Brushless is a whole new ball game - lower revs, huge torque, cool running etc, Alan worked out the Thumper is rated at 1hp.

Strongly recommend you get in touch with Debsnal he knows how to make big heavy models move quickly, where to get the goodies etc,
especially after having witnessed his twin waterjet powered lifeboat at Wicksteed in action ( this has 2 Thumpers in it, video on Youtube).

I am cooking up ideas of a big 56", full blown scale Huntsman 28 in round Britain livery etc, with twin brushless and lots of cells,
have you considered twin in your 42", that should make her sit up and go!
Regards Paul
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #16 on: July 05, 2009, 12:27:18 AM »

High Paul, many thanks for your reply, I saw the pics of your Hunts, very impressive, I am at a standstill now with mine (its a refurb, not complete from scratch). I decided to get it running right before all the fiddly bits went on, and thats the problem.

Ran it last week for the first time, with set up similar to your original, with the graupner, great motor, we also tried a 12v 700. and a 9.6v 700, with various props, and different gear ratios. The 12v, which was great for direct drive, but very inefficient was awful, 9.6 and 8.4, virtually no difference, infact the 9.6 ran a bit cooler, but the 8.4 just revved that little bit more. Funnily enough, on a borrowed 40mm (I think!) steam prop was equally the best, but it was borrowed, and the  "x" was mine, thats the only reason I stuck with it!.

People that saw the boat run where impressed, but it just needs that bit more speed to get the hull working. I have to buy a new esc, so was thinking lets just go brushless and have done with it, but the motor thing is confusing. What do you think of the 2 motors listed? It was interesting seeing your comments, what motors have you had any success with, I would imagine my boat is heavier than yours?

I did try and contact debsnal by pm, but no reply, and I am hoping andrew has some findings soon because I would like to get this sorted soon. I have started putting the fittings on now so its almost completed. I thought about twin screw, but have left ity too late, I thought it would be faster  than it is, and now dont want to start ripping apart the hull, and the additional expense of 2 esc's, 2 motors, packs etc. If you can offer any further advice please let me know,

Martin, good call re the reversing esc,. I would like reverse on this boat, thanks :-))
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malcolmfrary

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #17 on: July 05, 2009, 10:05:13 AM »

Looking at a downloaded pdf for the ESC originally mentioned, it looks like the reverse is got by double dabbing the stick into reverse - 1st dab stops the motor by using the "brakes" and the 2nd dab engages reverse.  This is great for cars, where stopping the motor stops the vehicle, but could be a bit fraught with a hull with plenty of inertia approaching either the bank or another hull.  On a boat, reverse is the brakes.
 If an ESC was to be sold as a marine item, I would have thought it possible to program the brake to a stop function into the ESC so that it would happen transparently, making the control like a normal ESC.
What happens when coming OUT of reverse? Is that a double dab as well?
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #18 on: July 05, 2009, 12:54:37 PM »

good point malc, you are right regarding the reverse acting as a brake, on the water trial last week, I noticed that this hull seems to carry a lot of forward inertia and I needed the reverse to slow it down, so a esc without reverse is a none starter, I will have to look into that, I just assumed with it being water cooled, and listed as a boat esc, reverse would have been as normal, more info digging needed!
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monarch

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #19 on: July 05, 2009, 06:46:42 PM »

Try this esc plenty of power, so should run cool on most boat motors - http://cgi.ebay.co.uk/Hobbywing-EZRUN-150A-SD-BLSESC-for-1-5-1-8-Car-x1_W0QQitemZ110410066639QQcmdZViewItemQQptZUK_ToysGames_RadioControlled_JN?hash=item19b4f3eacf&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1688%7C240%3A1318%7C301%3A0%7C293%3A2%7C294%3A50.
It also has proper forward and reverse.
As for as brushless motors are concerned used with boats I think about 1000rpm/v is ideal and re prop as required to give required speed, hope that helps.
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MRZIPPYXXXX

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #20 on: July 07, 2009, 10:19:05 PM »

Hi Paul
Firstly must point out my model is the Hunts little brother, the 33" Swordsman and is built deliberately light, too light in fact and needs ballasting,
you can imagine how quick it is with the same power as your larger and heavier Huntsman, and pulling a 50mm 4 blade scale brass prop!

My motors are all of the Outrunner type IE. spinning outer case, lower revving with monster torque,
the motors mentioned above are of the Inrunner type IE normal static case, high revs, low torque not really what we want in a big heavy model.
Inrunners are really for suited for my other passion, lightweight silly-fast electric racers, using surface piercing props, again your Hunts is submerged drive.

I think Debsnal has posts re Huntsman power earlier in this section on the Mayhem site, and as AndrewH has mentioned the lifeboat route would seem
a good starting point, anyone who can make one of those half cwt monsters move, has to be doing something right!
There are posts on this site from Lifeboat Paul re what powered his model, after his success at the 2 years ago Wicksteed Mayhem bash.

Also my fellow Leiester club pal runs the big old heavy 46" Aerokits Crash Tender with a French "Plug & Fly" brand aircraft tiny brushless
approx the size of a 600 brushed motor with the speed controller built onto the back end of the motor case to form a square bulkhead mounting,
this goes really well, about as quick as its original Merco 61, available from GeeDee Models Nottingham, although I think more speed and cheaper is the Lifeboat
route.
Hope this is a help Ia m struggling with a broken MAC keyboard at present if thers a system for passing phone numbers over the Forum it would be so much easier
than trying to type what ones thinking.
Regards Paul
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red181

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Re: Huntsman 28 going from brushed to brushless, advice please!
« Reply #21 on: July 15, 2009, 12:58:19 AM »

after lots and lots of research, its time to be brave and get a motor. I have decide to go for a feigao 540XL (Exra long), 10 turn, this gives revs just short of 1700/volt, is a reputable brand,  will take up to 24 cells, and gives up 1000w max, so its should at least be as good as the 700bb turbo (I hope!) as the power poutput is increased,  and should offer the flexability to try different gearbox ratios, and prop sizes, then when the bank has recovered, lipo batteries. I wil have to go for a 90amp esc, looks like from fleabay, the motors are only found in 2 places, one is UK, but quite expensive. If anyone can suggest a retailer for these motors, pref UK, please let me know

If all fails, then the motor and esc will end up on fleabay!! The boat is almost completed now, so hopefully this set up will give the speed that I want. Info for brushless on this sort of size boat is very scarce, so its really going to be trial and error, what this space :D
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