Model Boat Mayhem
Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: LarryW on October 01, 2011, 05:35:43 pm
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HI i have now completed HDML ......but stuck on how to control the 2 540 motors , the duel ESC are quite dear , so are 30mm brass props , to drive the model ,
the question is there cheaper way to control the motors and drives monies is tight LARRY...
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http://www.action-electronics.co.uk/pdfs/Twin%20Motors.pdf (http://www.action-electronics.co.uk/pdfs/Twin%20Motors.pdf)
DM
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You can use two Esc,s one for each motor.Or use one Esc of sufficient capacity to run both motors.All should be fine as long as your rudder is big enough.If using two Esc,s then later when funds permit you could add a mixer.John.
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THANK YOU DAVE, i will be in touch , CHEERS Larry....
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Good choice Larry (http://i124.photobucket.com/albums/p8/DickyD_photos/drinking25.gif)
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John: What would you recommend for a good mixer please? I have a lean 1.34m hull, 20mm props 60mm apart and a large brass rudder between. Motors are JP400's with two Mtroniks Marine 20A ESC's.
I tried one mixer but at low speeds the props kept flicking forward / reverse with almost any rudder movement making it hard to control, so I have reverted to a Y lead. Would be nice to be able to limit it to say 30% or more rudder with 10% or less motor.
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Bob,
On twin shafts the best mixer is the one between your ears.
With a little practice you can get this model to spin on the spot with just 2 x Speed Controllers.
Bob
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Bob,
I should of said I am running on one channel for the motors and one channel for the rudder. I originally had each motor on a separate stick both drives seem not exactly the same from the ESC's, steering a slow straight line was as sensitive as a helicopter. I have seen other boats that do this really well at very low speeds.
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There are still other ways to improve the steering.
If the motors overpower the model and you only use about 1/2 or 3/4 throttle fit a microswitch in the motor circuit which is operated by the steering mechanism/servo.
This will cut out the inner motor and if you go full ahead wont have much of a speed drop.
On my HDML I just have 1 ESC for both motors and she handles quite well.
The other option of course is a mixer, but I prefer these on 3 shaft applications.
What radio set are you using?
Bob
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"What radio set are you using?"
A Planet T5. The Y lead works reasonably well, and she turns in about 2 x length provided I have sufficient way on her. Just asked to find out if I can further improve low speed control by using a mixer.
On my current build, a WW1 destroyer, I have twin motors with a single ESC.
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http://www.action-electronics.co.uk/pdfs/P94.pdf
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That spec is certainly exotic, especially if you want bowthrusters too, but far too large to fit in my boat - and £79.
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hi ya Larry W
Another alternative which everybody seems to forget about, is that ACTion also do a dedicated mixer and when I get time, I will find out the number & price for you. Dave might have the up-to-date price.
This doesn't have the same facilities though built into it as the P94, e.g. tank steering and soforth. It just deals with mixing the 2 speed controllers and the rudder; I have tried several speed controllers with this mixer - e.g. Electronize and a couple of home-made mixers - and it works really well with them. So you shouldn't have any problems using MTroniks speed controllers with them.
The other advantage of this dedicated mixer is, over the Y-tail mixers which can be bought from companies such as MTroniks is that these do the correct mixing of rudder and prop direction when going into reverse - the Y-tail ones apparently dont.
http://www.action-electronics.co.uk/pdfs/P40C.pdf aprox £30
Aye
john
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That spec is certainly exotic, especially if you want bowthrusters too, but far too large to fit in my boat - and £79.
Just to correct any misunderstandings, P94 is NOT designed to run a bow thruster in addition to the two main motors. As the instructions state, the connection (at pins H2) for a third speed controller is straight-through from the throttle stick and is intended for a central motor or a P100 Noisy Thing. The bow-thruster in a conventional twin-motor model is controlled from a third channel via a separate speed controller. You can't run throttle, steering and a bow thruster properly from just two connections to the receiver. P94 can be used (in Mode 2) to operate a pair of stern- and bow-thrusters but you would need another unit for the main motors.
As regards the price, two 20A speed controllers and a W-Tail mixer from another well-known manufacturer will cost £73 at current list prices. The footprint of these three units together is very little less than one P94. You then have to connect and set-up three separate electronic units and you'll finish up with two high-frequency ESCs (which have been known to make some motors squeal) and a mixer with none of P94's different operational modes and adjustments. You've saved yourself six quid.
As someone used to say, suit yourself. BTW P40C is £28 to UK+EU customers.
Dave M
Forgot to mention that P94 will shortly be available with Autoset, which means no fiddling about with transmitter trim levers to get the motors to stop and start together - and, of course, no flashing LEDs and buttons to push................. 8)
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You will not go wrong with ACTion & the P94, on top of that if you ask Dave nicely he will at no cost to you do you a wiring diagram so save yourself a lot of headache & get the MAN on the job. Mick B.
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Sorry guys, but I am unlikely to "saved yourself six quid" by chucking out two almost new 20A Mtroniks, and even if I did the unit will not fit in the space between motors and my big battery. Maybe a good idea for a new build or a larger ship.
I will however check out the P40C. It was a mixer we were discussing when the link to the P94 was posted . . .
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Bob,
On twin shafts the best mixer is the one between your ears.
Bob
I Have to say, i completely agree with this. I run several boats with three shafts / props and enjoy the challenge.
Problem with mixers - they are good for set pieces but do not take into account wind / stream / prop position or other variables.
Being a powerboat instructor (amongst other things) i do enjoy the challenges / understanding it gives me ..... I have been known to use model boats in my training courses ... especially when explaining paddle wheel effect.
Regards,
Kim
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Thanks Kim. I can turn the boat in just under twice its length provided I have sufficient way on her, but do not expect to 'spin' it like a Springer, even with a large rudder between the props. I was just interested in what other modellers did for low speed turn control - But as stated nothing beats practice O0
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HI ALL, thank you all for input, all very useful thanks again .....LARRY..... :-))
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might be a bit late but i have 2of these in a mfa attack running 850's
http://www.ebay.co.uk/itm/Mtroniks-Super-E-Trucker-Hi-Power-RV-ESC-Speed-Control-/180730675302?pt=UK_ToysGames_RadioControlled_JN&hash=item2a14634066