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Author Topic: twin motors  (Read 3552 times)

stag

  • Guest
twin motors
« on: November 15, 2010, 12:09:37 am »

i am thinking of building a bait boat and only want to use 2 channels for power and steering, I'm going to use a jr3810 transmiter. it will have a motor in each hull but no rudders so will be using the motors to steer it with. can this be done with  esc`s
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TomTheKraut

  • Guest
Re: twin motors
« Reply #1 on: November 15, 2010, 08:57:11 am »

Yes.
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50mm

  • Guest
Re: twin motors
« Reply #2 on: November 15, 2010, 09:16:11 am »

3am sucks on nightshifts its so slow!

Tomthekraut, your answer to dudes question aint really helpful is it? the word yes.... don't explain much, and leaves a load to be desired...

Stag. lets give you some right info on this topic..

Using 2 channels can be used to control two motors with the use of micro switches that control the 2 esc's (one for each motor) attached to a servo.
this is commonly know as skid steering or tank steering so no rudders are needed.

The down side it that it is quite complicated electrically to setup, and using only 2 channels how are you going to control the hopper to drop your bait?

Here's a better suggestion which can do the job better and be less complicated.

Take 2 motors each should have there own esc' probably around the 15A mark (motor size pending) now you need a minimum of 4 channel radio for this set-up im sure you can pick one up pretty cheap where you are the 2.4ghx are pretty good value.

Okie attach the port esc to one stick on your TX through the RX channel (normally be forward and back on a 2 channel) then the starboard esc to the other channel ( which would have been the left and right stick , but in this case its also have forward and reverse)

Plug your batteries into each esc to power that motor or link then power up using a 6v cell or something, remove the BEC from ONE of the esc so not to over power the rx and blow it up!

To go forwards push both stick forward, to go back pull both sticks back, to go left or right one stick forward and one stick back.

Hopefully if you chose this method you have a 2 spare channels in which one of the left/right functions can be used to control the bait hopper servo to drop your load and close the hatch again.

This should get ya started  :-))
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ACTion

  • Guest
Re: twin motors
« Reply #3 on: November 15, 2010, 09:40:57 am »

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TomTheKraut

  • Guest
Re: twin motors
« Reply #4 on: November 15, 2010, 10:32:41 am »

Sorry, didn't think of stating the obvious.
"Yes" means "when using one motor with appropriate ESC in each hull - as was described in the question - then yes, steering through independent motor control will work."

The simplest way to achieve the desired control would be:
- One motor plus one ESC in each hull (as is stag's plan)
- One motor/ESC-combo to be connected per channel (e.g. ch.1 = port combo, ch.2 = starboard combo).
- On the transmitter, turn the "steering stick" by 90 degrees so it moves not left/right but up/down (makes life easier but is technically not necessary).

Resuilt:
Both sticks forward = boat moves forward.
Both sticks back = boat moves back.
Left stick forward, right stick neutral = turn to starboard.
Left stick back, right stick forward = turn to port sharply.
And all states in between.


The whole principle (two sticks controlling two independent motor/esc-combos) is sometimes called "Tank control" and - according to the way the question was asked - seems to be the thing Stag had in mind.

The Action gizmo does basically the same thing but in a more elegant and electronic way of handling the transmitter sticks (standard stick layout can be kept).


As for the dimensioning of motors, ESCs, props etc. we can't make nominal suggestions because we lack any information about the installed motors.
The only reliable figure I would venture to give is: dimension the ESC for 2*(max current of the motor) at least - and don't use the peak figure for that but the constant current figure of the ESC. That should eliminate the "advertising risk" ...
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Lord Bungle

  • Guest
Re: twin motors
« Reply #5 on: November 15, 2010, 01:58:30 pm »

I am contemplating something similar on my next boat, but will be using a rudder. this would make your life easier and should make contoll a lot better (IMO).
just a query if you are going to use a JR 3810 as a transmiter (as I just looked the specs up) what are you going to do with the other 7 channels?
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stag

  • Guest
Re: twin motors
« Reply #6 on: November 15, 2010, 05:34:30 pm »

the other 7 are for lights, hoppers, spot light on the front and 2 hook pins on the back.
the tank way is good but is there a way of using the fwd and rev stick to power both motors at the same time so each would have the same rev`s then use the l and r stick to some how slow the left or right motor down and steer it that way
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ACTion

  • Guest
Re: twin motors
« Reply #7 on: November 15, 2010, 05:54:14 pm »

is there a way of using the fwd and rev stick to power both motors at the same time so each would have the same rev`s then use the l and r stick to some how slow the left or right motor down and steer it that way
Yes - just read the whole article as per my earlier link. It explains exactly how this can be done.
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stag

  • Guest
Re: twin motors
« Reply #8 on: November 15, 2010, 06:06:55 pm »

got it action, thanks will read it tonight.
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787Eng

  • Guest
Re: twin motors
« Reply #9 on: November 15, 2010, 06:26:33 pm »

Use the KISS (Keep It Simple S****d) approach with that nice 8103 you have all the mixers you need. There is absolutely no need to use fancy external mixers.
I use the elevon mix with a bit of aileron differential dialed in....and ALL my dual prop models will spin on the spot....And I have 3 of them, by just using one stick (ELV/AIL).

Mark

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