RC for Submarines

Hello. I am new to both this website and submarines.
It has been suggested by Fred that I seek out david f, who is the man with most of the answers.
I have been told that 2.4ghz will not penetrate water so it is no good, but Fred disagrees.
I have a Taranis FrSky x9d which I use for my surface fleet and my question is, can I modify this for subs?
Thanks
Steve

Those that are using 2.4GHz must keep a part of the antenna above the surface. Usually it is put in a scope or semi scale sub antenna to hide it. If you want to travel completely underwater, you will need to go with a MHz frequency legal in your area.

Anyways, Welcome aboard. What sub are you looking to build?

Ah, not as easy as I thought then. Best I go for 40mhz?
I had my heart set on a Uboat type VIIc, but it's now a toss up between that and the British 'S' class - I'm siting for details of a second hand 'S' class.
I have, up to now, built surface warships, but my wife says my fleet is clogging up the garage so I must get rid of a few, hence the VIIc.
BTW, what's a BBCode?

BBCode is a bulletin board markup code. So any formatting (like making letters bold) uses BBCode.

Cormorant,

the FrSky Taranis x9d does have one option available to it that i have been using for the last two years. it works well, but not as good as a 40mhz setup would work.

FrSky makes a transmitter module that plugs into the back of the x9d, as well as several different receivers...

these are made for long range drone flying, but, as i have said, i have been using them exclusively for my model submarines for the last two years (everything else r/c uses 2.4ghz)

https://www.frsky-rc.com/product/r9m-2019/
https://www.frsky-rc.com/product-category/receivers/900mhz-r9/

these use 915mhz for USA, and 868mhz for europe.

I personally own two of the r9m modules, and the following receivers:
2 original r9 receivers
2 original r9 slim
3 original r9 mini

although most of these receivers have been replaced with newer models, I don't think there is a direct replacement for the basic r9 receiver, which is kind of a shame.

Hello,

due to my own experience the "historical" 40MHz frequency band is still recommended for Radio control of model submarines when you want to dive somewhat deeper and not only to submerge close beneath the surface. Depending opon the electrical conductivity of the water (sweet water) Radio control contact can be maintained up to several metres depth, mostly sufficient to go down to the bottom of pools of public swimming baths as you can see in the following Videos taken of my class 212a submarine and from on board of my old class 206a submarine.




In seawater of course it is quite different and contact will be lost very soon when the model is beneath the surface.

27MHz is an alternative but I don't know whether these "historical" RC frequency bands will be longer allowed for RC purpose in future as the majority of RC modellers has changed to 2.4GHz since years.

Hi Hermann,

Good to hear from you and I hope you are all well in these difficult times.

You are right. Technically the lower the frequency the better, with 40 Mhz coming a close second to 27 Mhz.

In practice the selection is a compromise between technology, available equipment and regulations.

Tim Senecal has offered up more choice by pioneering openLRS on 433/458 and 900 MHz. I have been using openLRS on 458 for several years now and I wouldn't use anything else now. The availability of telemetry is a considerable bonus (now that I have got it working reliably for me.) (See other thread posted today.)

Lovely pool shots, by the way. I can confirm that 459MHz gives up the struggle at the bottom of a typical swimming pool. (Don't forget to set your failsafes!)

Keep well!

David

Hi David,

and thank you for your kind reply. Yes, my family and I are still well in these difficult times and we try to stay healthy. I am still on work and not retired yet and also kept very busy at home by the family, house and garden so there is not much time left to be very active in the AMS forum

You are absolutely right, the choice of the frequency is a compromise between technology, availability of equipment and regulations. Up to now I have retained my 40MHz RC system and although there is no telemetry I will use it further as long as possible since the higher frequencies on 433MHz or 458MHz as well as 900MHz are not allowed to be used here.

How is your experience about deep diving using these higher frequencies?

Kind regards and keep also well and stay healthy
Klaus-Dieter

Cormorant wrote:Hello. I am new to both this website and submarines.
It has been suggested by Fred that I seek out david f, who is the man with most of the answers.
I have been told that 2.4ghz will not penetrate water so it is no good, but Fred disagrees.
I have a Taranis FrSky x9d which I use for my surface fleet and my question is, can I modify this for subs?
Thanks
Steve

I feel that I must just clear up a few points in the above quote, Steve and I did talk for some time on this, and as we talked I did say about the open R/S system for a full working sub and to talk to David for more details, I mention that one of the members in my local club has used 2.4ghz in his surface only sub this is where I think Steve may have got his wires crossed with regards to the 2.4ghz. Steve also asked if an Open R/S module would fit his TX as I have never used a Frsky I have no idea if one would.

Keep safe

Fred

Hi Fred,

Thanks for clearing that up. Lot's of experience and trials have shown that 2.4 is no good for subs other than surface running.

To answer Herman. Using 958 Mhz (Later edit - a typo should read 458!) over the last few years is good. It is hard to say, but I don't think it is very good for controlling at depth,  though. I have controlled a sub in a measured 1m of water with the TX directly above it. At any horizontal distance the control depth is probably less than that but you do get a very useful visual and audio signal of falling signal strength. You do need to make sure that you set the fail safes.

So all in all it is very practical and low-cost system and the Telemetry (now working again for me - thanks Tim S!) is a considerable bonus.

David

david f wrote:Hi Fred,

Thanks for clearing that up. Lot's of experience and trials have shown that 2.4 is no good for subs other than surface running.

To answer Herman. Using 958 Mhz over the last few years is good. It is hard to say, but I don't think it is very good for controlling at depth,  though. I have controlled a sub in a measured 1m of water with the TX directly above it. At any horizontal distance the control depth is probably less than that but you do get a very useful visual and audio signal of falling signal strength. You do need to make sure that you set the fail safes.

So all in all it is very practical and low-cost system and the Telemetry (now working again for me - thanks Tim S!) is a considerable bonus.

David

david, small typo... you wrote 958mhz, and should have written 458mhz for the equipment you are using.


as to the original OP, david and i are the ones that originally investigated these newer freqs (i started looking into 433mhz, and david did all the legwork for 458mhz)... i switched to the 915mhz equipment when most of the manufacturers of the 433mhz equipment gave up and stopped making it. I haven't kept up on availability since switching, but i do think that hobbyking is the only company making 433/458mhz equipment now.

Thanks for pointing out the typo.

In these "lockdown" days I've been spending a  bit more time in the workshop and I reached down my converted openLRS TX  gathering dust:

https://www.theassociationofmodelsubmariners.com/t1553-using-an-old-tx-with-458mhz-openlrs

I switched it on and it works fine.

I don't know why more people don't have a go at converting an old TX to openLRS?

All you need is an old TX you can gut. An Arduino Nano and a Hobbyking TX module and receiver. (Both still available at Hobbyking for about £25 and £11 respectively. Not sure about delivery times at the moment though?)

The instructions and software are all available (My thanks to John Wrennall for finding this and Phil Green for doing all the hard work) at:

http://www.singlechannel.co.uk/

(Go to the archive page and and find " P17]  Sketch for 7 channel proportional encoder using the Arduino, with Single-Channel mix [Superseded - see below]" for the Arduino sketch I think I used.)

More information form John Wrennall is in the middle of this thread on Page 5:
https://www.theassociationofmodelsubmariners.com/t83p100-openlrs-and-2-4-ghz-and-submarines?highlight=openlrs

Just to clarify, you can use the existing transmitter electronics for the Hobbyking modules via the trainer socket. If you choose to gut the electronics you will need the elegantly programmed Arduino from Phil Green,

A good way to spend ones "Covid 19 isolation days?!

Keep well!

David