Internal Workings of an R/C Submarine

[He Who Shall Not Be Named]

An excellent observation as to the receiver bus needs of our submarines, John. Clearly the stock ESC's (specifically, they're BEC circuit) are not up to the task of supplying device current load at the 5-volt needed off the receiver bus. Other than 'robots' I can't think of any other r/c vehicle out there that presents a higher current draw off the bus than r/c submarines. It has been through Andy's and your prodding that finally convinced Mike and me to secure, offer, and promote use of a dedicated BEC within our SD's. Thanks, guys.

David

[Slats]

It would be helpful if some manufacturers of ESC's were a little more forthcoming about the current capacity of the built in regulators used for the BEC's. Some will give out an arbitary figure like 5 volt 1A BEC. But 1A at what main voltage? The regulator might supply 1A of current from say a 6 or 7 volt system, but what if you hook it upto 12 volts. Then the regulator is working much harder.

Unfortunately I see a lot of devices used which are barely capable of supplying a single servo, let along two or three. Some ESC's are equipped with pretty good regulators. The Mtroniks 'sub' range of ESC's have a decent linear regulator mounted externally to the main case. This should be enough to supply a reliable feed for about three normal analogue servos, provided you don't go too high on the voltage (no more than 12 volts and preferably lower).

Switchmode BEC's are capable of supply large amounts of current fairly efficiently. They are electronically 'dirtier' than linear BEC's, but I know of a few people using them with no problems to report.

The BEC issue is something that I have been banging on about for years.
Since I have been running Switchmode BECs I have had zero glitches on the water.
I totally agree with Andy on this - whom has been instrumental in providing generous and always on the mark information.

A rule of thumb I use for those wanting to know the limits of the on-board or linear type BECs of ESCs is that whatever the manufacturer states the amperage to be - accept that amperage is only ever available at the lowest input voltage and more to the point, accept that the figure stated is a peak rather than continuous amperage available. If the ESC with the BEC has an input voltage of 6 to 12 volts, and you running 12 volts - halve the available amperage. That is set up a linear equation - starting from the lower input voltage and incrementally and proportionately reduce the the stated amp peak on the ESC for every additional volt you are inputting above the minimum input voltage. But with the widespread low cost switchmode BECs now available far better rule of thumb is to simply buy a 3amp or higher unit and neutralise the on board BEC of the ESC but removing the red wire going between the ESC and the RX.

The only thing I'd disagree with is my experience of using the Mtroniks ESC's BEC is I have had a string of BEC failures. And this was running 7.2v input. It might be the fact I prefer fullsize servos, but even with just three in operation + the small servo for the SD vent / blow operation I have had more glitches than any other ESC. Neutralising the BEC from the ESC and running the switchmode type separate unit has been the key to rectification and success. Mtroniks make a fine ESC. I use them, but its SOP for me to fit the separate BEC.


J

[Anuci]

Thank you again for your input, Subculture. Although I've read some of your comments and input on a variety of subject matter, I don't believe I've actually seen any postings relating to the models you may presently own or have owned in the past. Then again, I may have simply missed that information. I'm sure we would all enjoy learning of some of your past projects, or at least one by which you may have regarded as your favorite R/C model submarine. The rc equipment you had personally found most functionable and reliable enough to have installed within your own submarine would certainly be interesting reading, and obviously useful to many of us in the hobby, for certain.

Regards,
Al

[Subculture]

Andy has long advocated the stand-alone, high current BEC.

It would be helpful if some manufacturers of ESC's were a little more forthcoming about the current capacity of the built in regulators used for the BEC's. Some will give out an arbitary figure like 5 volt 1A BEC. But 1A at what main voltage? The regulator might supply 1A of current from say a 6 or 7 volt system, but what if you hook it upto 12 volts. Then the regulator is working much harder.

Unfortunately I see a lot of devices used which are barely capable of supplying a single servo, let along two or three. Some ESC's are equipped with pretty good regulators. The Mtroniks 'sub' range of ESC's have a decent linear regulator mounted externally to the main case. This should be enough to supply a reliable feed for about three normal analogue servos, provided you don't go too high on the voltage (no more than 12 volts and preferably lower).

Switchmode BEC's are capable of supply large amounts of current fairly efficiently. They are electronically 'dirtier' than linear BEC's, but I know of a few people using them with no problems to report.

[greenman407]

Welcome back Al! Good to hear from you. You owe me a phone call.

[He Who Shall Not Be Named]

Andy has long advocated the stand-alone, high current BEC. I, only recently, came to appreciate the utility of the device -- it solving many of my randum 'glitching' problems. A device we now advocate being used within all 2.5 and 3.5 SD's (and our soon to be released 3" SD).

David

[Anuci]

Hello All,

Thanks Caswell, for introducing this new catagory into the Sub-Driver Forum. Hopefully some may find the info. posted here useful, providing if nothing more, food for thought, this while setting up their own R/C submarine application.
Obviously, the more folks who share their personal experiences, relating to their set-up, and particular type of electronics they have used in the past, or have presently installed within their model, the more comprehensive and informative the subject matter in this forum catagory will become. The success of this catagory is up to you the membership, as well as with the many readers out there who have been there, done that, and have found solutions to electronics issues respective to model submarines by which they woud like to share with others in the R/C submarine community who may have exhaustively been looking for help.

Positive results, and a well running sub should be at the fore-front of the information provided.
Having said that, it is well known that issues occur from time to to time which may affect radio reception and such, particularly while running submerged in various pools and ponds, by which the water quality may become a major factor in this regard. These projects have long been said to be, " A work in progress".

Allow me to start the ball rolling here by first saying, with each and every application comes a different set of circumstances.
However, given an opportunity to simply reference the various applications as posted, we may hopefully increase the probablity of success when mixing and matching the various components within the confines of your model submarines motor compartment.
I have personally found good success with the following basic set-up of electronics, by that I mean( No Glitching ) etc. when bench testing, and out on the water.
IMO, and as previously mentioned, the boat runs reasonably well out on the pond, as I'm hoping continued success with the latest instalation of a stand alone BEC , which has recently been incorporated into the electronics and suggested by (Subculture)-Andy Lawrnce, Dave Meriman, and others on this site, this to further avert the posibility of electrical issues relating to the draw of power off the various electronic devises within the model itself, and rather than depending on a bec which simply may have a low Amp output. Some ESC's on the market today do not specify the output amperage of the BEC incorporated within or made to handle multiple devises operating at the same time, rudder, stern planes, dive planes, and possibly a pump or ballast servo.


Model Description: 1:48 scale WWII Gato class Submarine
Sub-Driver: Meriman/Caswell 3.5 Mod. 2 = (Twin Drive motor)
Basic ( Gas ) Ballast System

Motors: Twin- Traxxas- Titan Marine-550 air-cooled 14.4V
ESC: Mitronics- Viper Marine-40
Receiver: Sombra Labs 8 - 8 channel RX ( no longer available)
Pitch Controll: Mike's Sub Work's - UPC-1 controller
Servos: Caswell- BT100 (Standard servos)
Battery: Venom- 5000Mah Lipo
UBEC: RCTimer- Output 5V- 3A continuous
Failsafe: Mitronics- Micro failsafe
Transmitter: Polk's- Tracker- lll (8) channel transmitter- This radio is no longer available