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Old Jan 25, 2011, 04:34 PM
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Help!
Using an aircraft-style radio for a submarine, programming advice requested

For a project, some peers and I are designing a submarine. My role in the project is powering the propulsion motors and enabling (completely wireless) remote control.

I want to propel 4 motors (positioned around the submarine) using this wireless remote controller. I am sticking with 75MHz because 2.4GHz's high frequency would not propagate well in water and I believe 75MHz is a legal surface frequency. The motors are a bilge pumps motors (with the bilge pump casing removed, leaving just the motor). The motors will have propellers attached to the motor shaft. It is a two-wire motor, and Ive been able to reverse it by connecting 9 1.5V D batteries in series in each polarity combination. I want to attach a 2-wire ESC to each motor.

My question is this: would I be able to program this transmitter to operate the motors according to the attached logic table? x represents forward spinning, I would just do some tabletop testing and see which way I need to wire +/-. CW and CCW are arbitrarily chosen to represent opposite directions. I have left out major details about the project; my main concern (at the moment) is the feasibility in programming this transmitter/receiver package but I will provide additional details where necessary. Im completely unfamiliar with hobbyist controllers; this is all new to me. Thank you.

6-channel 75MHz radio (capable of mixing) http://www.robotshop.com/hitec-laser-6-1.html
Brushed ESC http://hobbyking.com/hobbyking/store...idProduct=6468
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Old Jan 25, 2011, 05:18 PM
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Miami Mike's Avatar
Miami Lakes, Florida, USA
Joined Mar 2003
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I think what you'll need is car ESCs with reverse. I didn't see any for brushed motors on that HobbyKing site though.

By the way, I think your "Turning Left" and "Turning Right" entries in your table are mixed up. For example, if you have only the left motor forward spinning, you'll turn right, not left.
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Old Jan 26, 2011, 09:48 PM
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Oops, you are very correct on the left/right mix up.

Brushed ESC with reverse: http://www.rcplanet.com/HPI_EN-1_ESC...v_p/HPI340.htm
This will work?

How easy is programming a transmitter? Would those functions be possible?
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Old Jan 26, 2011, 10:46 PM
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Miami Lakes, Florida, USA
Joined Mar 2003
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I'm trying to understand how you're setting that thing up, but I'm not sure that I fully get it. Apparently you have a left motor and a right motor that propel the model forward. You won't need ESCs with reverse for those two motors unless you want to be able to back up. Otherwise, ordinary ESCs like the one you originally linked to will work.

Question #1: Do you want to be able to back up?

You also have a forward motor and an aft motor that apparently each deliver thrust up or down, depending upon the direction of rotation. If the two motors are independently controlled, you'll be able to pitch the model nose-up or nose-down, like the planes do on a real submarine. If you can't control them separately then you'll have no control over pitch, but it'll be possible to run both motors with a single speed controller that has reverse. This can be done with brush motors but can't be done with brushless motors.

Question #2: Do you want pitch control?

I think what you want to do may be possible with that Hitec Laser 6 radio, and it may not even require any fancy computer mixing. I picture the forward and reverse functions working sort of like the two levers that control a tank or bulldozer, and the up and down functions would be controlled by moving the sticks left and right. You'd have to make some minor mechanical modifications to one of the sticks inside the radio so that the left and right sticks work the same way, but I suspect that won't be too difficult.

Disclaimer: I'm not promising that you'll be able to get this to work, so my advice has a money-back guarantee limited to the amount you paid me for it.

P. S. - Make sure the ESCs you get can handle both the voltage and current you'll be using to power your motors, especially if you're going to run two motors with one ESC. The ESC with reverse that you linked to is limited to 8.4 volts and can't handle the 9 1.5V D batteries in series that you mentioned in your first post.
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Old Jan 28, 2011, 02:10 PM
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We will have 4 motors, one mounted on each side (oriented "forward"?, along the longitudinal axis) and one each on the front and back (oriented either up or down, I need to double check with the mechanical fellows). I don't care about variable speeds; as long as it is moving forward at some speed, it's fine by me. I also don't care too much about pitch control, as long as I can keep it stable with the controls. It does not need to back up, so for the side motors, I will use the original ESCs I linked. We can try using the ones with reverse for the forward/aft motors?

The bilge pumps (I'm trying to find a more informative website): http://www.westmarine.com/webapp/wcs...4&ci_sku=34144
They are brushless, but only have two wires. We've speculated that inside the motor, there is an internal speed controller, negating the need for a third wire.

I can purchase a few components first, to test with the motor.

Your help is much appreciated!
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Old Jan 28, 2011, 03:32 PM
AndyKunz's Avatar
Illinois
Joined Sep 2001
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Have you tried posting on the Submarines forum?

http://www.rcgroups.com/submarines-60/

Andy
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Old Jan 28, 2011, 04:33 PM
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Joined Jun 2005
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I don't think the bilge pump motors are brushless, they are just
12 volt dc motors. they don't need any type of speed control, they run at a constant rpm .
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Old Jan 29, 2011, 02:28 PM
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I've posted on a few of the other boards here, and some other forums, but I just had a radio-specific concern, so I decided to pose my question here.

The guys in charge of motor selection assured me that the motors were brushless (although there are only two wires). Regardless, I'm not interested in variable speed control; motor spinning and motor not spinning are good enough for me. I just need the ESCs for interfacing between the radio receiver and the motors (right?)

Attached is what I envisioned.
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Old Jan 29, 2011, 04:37 PM
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Joined Mar 2003
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If the motors are brushless but only have two wires, that means that they have electronic circuits instead of brushes inside the motors to switch the electromagnetic polarity, just like the fans inside a computer. That means two things:
  1. You probably can't connect the motors to ESCs because if they receive anything other than ordinary direct current, the control circuits inside the motors might behave unpredictably. (An ESC pulses current on and off at a high frequency to control motor speed.) You might have to connect one of the motors to an ESC to find out for sure what will actually happen.
  2. You won't be able to reverse the motors no matter what you do, so there goes your rising and diving functions.
If you want to use those motors in an on/off mode and you don't need reverse, you might have to use R/C switches similar to this one, although you may need switches with a higher current rating.

Maybe you should dump those motors and get some ordinary can motors with brushes, or better, three-wire brushless motors.
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Old Jan 30, 2011, 10:55 PM
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The motors only have a 1.9A draw, so these should be fine. Is the actual name just "R/C switch"? I searched "R/C switch" and "RC switch" and couldn't find anything else like that basic switch.
2 options now
1. Rethink amount/placement of motors. Place additional motors forward/aft for a total of 6, or maybe move dive/rise motors to top and bottom (on CG).
2. All new motors. The mechanical team bought a sample one of these bilge pump motors, and told me several times that it was brushless. When it arrived, I was VERY surprised to only find 2 wires. I had thought that the norm was brushed=2, brushless=3. I can see if the mechanical team can change their motor choice to a motor with three wires.

(Sorry this is now off-topic)
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