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[clockworks]

New to all this, so need some help.


I've bought a scratchbuilt Riva speedboat. It's fitted out, except for the radio gear. Twin brushless motors, twin rudders. I'm using a Futaba T7C Tx and Futaba 7ch Rx.
Rudder on ch1, throttle on ch3 for the RH motor/ESC. The LH motor/ESC is on ch5, and I'm using a programmable mix with ch3 as master, ch5 as slave. So far, so simple.


To improve handling at low speed I'd like to try and add some power to one or other motor along with the rudder input - RH motor (ch3) with left rudder, LH motor (ch5) with right rudder.
Is it just a case of creating a mix to add ch3 as a slave on ch1 left stick, and ch5 as a slave on ch1 right stick? Would that need 2 separate mixes, one for each direction?


How would this mix interact with the first mix that links ch3 to ch5?  If the rudder is turned left, increasing the throttle on the right motor, would the throttle mix automatically increase the speed of the left motor as well? Obviously that wouldn't be what I wanted.


Basically, do mixes interact, or are they completely separate?


Or, am I doing this totally the wrong way

[Howard]

Hello,
 If am right and someone on here will tell me if am wrong but ACTion  at component model shop on here look in the Traders section do just what your looking for.
         Regards Howard.

[morley bill 1]

Hi you could try tank steering I find it better than any electric mixers Bill..

[clockworks]

I spent an hour playing with the Tx this morning, got everything working as I hoped it would.


Mix1 adds ch5 to ch3, so both motors work from the throttle stick, mix permanently active.


Mix2 adds between 0 and 25% right motor to left rudder


Mix3 adds between 0 and 25% left motor to right rudder


Mix2 and mix3 are both activated by the same switch, so that I can disable them for higher speed running. I believe that newer, high-end, Txs can use "conditions" so that mixes are only active in certain circumstances, for instance mixes disabled (or enabled) above a certain percentage of throttle stick.
Mix2 and mix3 motor power is added to the motor power called for by the throttle stick, so at 50% throttle input from the stick, and hard right rudder, the right motor will run at 50%, left motor at 75%.


All works fine on the bench, will have to see how it goes at the lake.

[DJW]

Hi CW


I see this post is a year old...  So was wondering whether you had success with the described TX Setup..?


I'm building an Amati Riva Aquarama and am hoping to use a similar RC setup rather than the dedicated 'Action' hardware, build log here:  [size=78%]https://www.modelboatmayhem.co.uk/forum/index.php/topic,64276.0.html[/size]


I have the Futaba T6EX Tx, using the V-Tail function and Mode 1 to get the motor / rudder mixing.


Best regards
David.

[clockworks]

Yes, it worked perfectly on the lake. Best thing was - it's free if you have a computerised Tx. No extra modules, so one less thing to fail.

I tried explaining it to a few club members, but it was like I was speaking a foreign language. One member did suggest it might be a good idea to hold a "how to program a computer radio" session. Something to consider when we are allowed out to play again.

[DJW]

Great to know the plan worked..! And I guess easier to tweak the percentages on the Tx while the boat is on the water. (Compared to dedicated hardware)


Here's short video of my initial mixing: https://youtu.be/wmmUGpZXJyA

[Big E]

DJW and Clockworks:-
Thanks for your notes on mixing (apologies for leaving my response so long!) for multi-engined models, in particular the excellent video on YouTube from DJW.  I have two three-engined boats (Vosper MTB and BPB Whaleback at 1/12 scale, so BIG) and have tried to get the things to turn using Action Electronics P40 units.  The Whaleback (brushed) works ok but the MTB (brushless) is a handful, especially at slow speed.  This isn't the P40's fault, just my inability to get the best out of my Spektrum dx6i.
I particularly like the manoeuvring trick on the left stick and I am very impressed that just by careful mixing this can be achieved.  At the end of the video you said that you could give mixing notes if required.  Well, I would love to see them if at all possible.
The average model boater seem to struggle with getting the best out of their radios and treat them as a necessary evil, whereas flyers seem to revel in playing tunes on their transmitters (just my opinion, no offence intended!) and I for one would love to read more on setting up radios to match boats.  Any guidance gratefully accepted.  A typical radio manual assumes a certain degree of understanding of things like mixing and rates which is absolutely essential when flying a helicopter or an acrobatic plane, but all the average boat requires is steering and throttle, so the radio manual doesn't help much when it comes to setting up. I even have trouble with binding!  However, you seem to have cracked all the problems I am experiencing, so I for one would love to hear more.......please.
Thanks and regards.

[DJW]

Hi Big E


Can I confirm that you have three motors on three shafts with 3 ESCs..?  And whats the setup with the rudders, three rudders and three servos..?


Thanks
David.

[Big E]

Wow, that was a quick response!  Thanks David. In short response, yes, both boats have three individual drives and three rudders each.
The Vosper has three brushless Propdrive 5060 380KV outrunners driving individual 55mm racing props, with individual Turnigy 120A ESCs. These are mixed via an Action Electronics P40E mixer in mode 1, i.e. the inner motor is reduced in speed on a turn (it's not clear by how much and I have noticed that the outer motor accelerates at the same time. I'm pretty sure it isn't supposed to but I haven't yet got round to finding out why.)  The middle motor is unaffected in a turn.  There is clearly something wrong with this setup at the moment (my fault) as even at idle, if a turn is initiated the outer motor accelerates madly and spins the boat around. Not conducive to gentle manoeuvres!  I should say that I have only just finished the Vosper and tried it out on open water for the first time this Tuesday.  It is VERY quick, even at 72.5" long.
The Vosper rudders (outboard on the transom) are mechanically linked and driven by a single servo, so no differential steering or capability to add it.  As it happens, it steers very well, even at high speed, so no real requirement for improvement here, although I am sure that the existing mixer unit throttling back the inner motor is necessary when turning.
The Whaleback (68") has three brushed MFA torpedo 850 motors, 157W each on 12 volts (LiPo), driving three 45mm racing props independently.  I have used an Action Electronics P94 dual ESC mixer on the outer motors and an A.E. P80, 20A ESC on the middle motor.  I made a differential rudder linkage for the three rudders (one servo) and with the mixer unit on the outer motors it turns very well (better than the real thing apparently which had to be throttled by hand in order to make it steer!).  This boat seems well set up and I am happy with the handling except at slow speed, I would love to be able to use the throttle (left) stick as you do to be able to reverse the inner motor and forward the outer at slow speed only.
In conclusion, the Vosper is the one that I would like to sort out and I would be very happy to learn how to set the Spektrum dx6i a) to de-sensitise the throttle at low speed, b) to progressively throttle the inner motor in reverse and slightly increase speed on the outer only at slow speed on the left stick (Mode 2) during turns and c) probably cut the top off the speed.  When I first tried it in a test tank I slammed the throttle from full forward to full astern.  One prop shed its blades, one prop unscrewed itself and one prop managed to survive.  Consequently, I tend to be very careful when opening the throttle now and I daren't slam it into reverse suddenly; not conducive to careful manoeuvres near the bank! 
If I could only sort out how to reduce the size of the photos I've got of both boats, I could send you some shots.  I'll try again.
Thanks in advance for any advice you can offer, I look forward to hearing from you and good luck with your boat, its looking superb.

[Big E]

David, I think I've managed to reduce the file size of my boat photos, so here they are.  You should be able to make out the internals and externals of both.  The Vosper MTB is grey overall and the BPB Whaleback has the black hull and grey superstructure.  I have a couple more photos too, so I'll stick them on another post.
Regards,


Chris.

[Big E]

Two more of the Whaleback, but now I can reduce file size I'm just showing off!


Chris.

[DJW]

Morning Chris


Wow, those boats are awesome, great work..!  Must look great being towed to the lake behind your car...!


 


So, I'm really not an expert when it comes to radio programming, I just try to figure out what I'm trying to achieve then break it down into steps that might help me get toward a solution.  I think I have it a bit easier too with just two motors, that centre motor makes it more complicated. But to start down the track here are my thoughts....


As I understand it you're wanting to set up the TX (and not use the AE devices) to keep rudders on the Vosper on the normal (horizontal) right stick with a single servo, and throttle of all three motors on the normal (vertical) left stick.  Then get the two outer motors mixed on the left (horizontal) stick.


So before looking at the detailed steps, I think a bench test rig would be an ideal start at your end, some testing without disturbing the pristine current layout of the boats in case it doesn't work.  This would require a spare receiver and three servos (labelled up to imitate the ESCs) plus maybe a fourth to make sure the rudder is behaving, do you have those available..?


Another prerequisite is changing the TX to Mode 1...  This is detailed here for the Spektrum:


https://www.spektrumrc.com/ProdInfo/Files/SPM6630-Manual_Addendum_Mode_Change_EN.pdf


Its potentially a bit painful as one boat might end up being Mode 1 and the other Mode 2...  If it works it might be worth a separate TX.


So as I understand it, the V-Tail on an aircraft is a V 'rudder' controlled by 2 channels / servos, and on my Futaba in Mode 1 it operates on channels 2 and 4 (with rudder on channel 1). So if you have your outer ESCs on channels 2 and 4, the left stick moved left and right would increase one and decrease the other when initiating a turn.  And as mode 1 puts the 'elevator' on the left (vertical) stick, moving up or down would increase or decrease the outer ESCs in the same direction.  Then its a case of swapping leads / reversing the channels if they're in the wrong direction, and playing with the mixing amount to adjust sensitivity. With this combination the boat should be able to spin on the spot, or in a controlled radius.


That leaves the centre ESC.... It can't be slaved to the inner or outer. We'd need to figure out with some manual reading whether another channel can be slaved to the 'elevator' (vertical left stick), assuming you have a spare channel.  If this can be done you could put centre ESC on it. This is the part I'm really not sure about.


I think that might just work, but I do think a test rig is best way to play / experiment with it.


What do you think..?


Best regards
David.

[clockworks]

It's been a while since I used a Spektrum Tx, so I have no idea if this is possible (might not have enough programmable mixes available):


Centre motor on channel 3 left stick.
Rudder servo on channel 1 right stick


Left motor on channel 5, right motor on channel 6.


Mixes to add ch5 and ch6 as direct slaves of ch3. This makes the 2 outer motors work the same as the centre motor for straight running.


2 more mixes to add ch5 and ch6 to ch1.  One mix would make the ch5 motor turn faster when the rudder stick is moved one way, slower when the rudder stick is moved the other way. The other mix would do the opposite for the ch6 motor. This way, the outer motor would speed up on a turn, while the inner motor would slow down (or reverse if there was no throttle stick input at the time).


You would need to have 4 programmable mixes available for this to work, but it would mean you could use your normal stick layout (mode), and not be reliant on using the standard V-tail or other mixes - it wouldn't matter if you moved the left stick side to side, or the right stick up and down inadvertently, because ch2 and ch4 aren't actually doing anything. It would be like running the boat on a normal 2 channel setup, but with added manouevrability.

[DJW]

Hi Clockworks


That sounds like a viable approach, I don't run Spektrum so not sure about the available number of mixes.


I think building a test setup would be a great start to check out what works.


Regards
David.

[clockworks]

I just had a look at the DX6i manual online, and it only has 2 programmable mixes, so my suggestion won't work.....


My Futaba 7C has 3 programmable mixes, so I can only use that setup for twin motors.
My "new" Futaba 14 has 5 mixes though, so I could do it with that transmitter

[Big E]

Sorry chaps, I did write a response to both of you yesterday but it doesn't seem to have reached MBM (probably my fault) so I will try again.  Now I've had some time to consider all your suggestions, for which many thanks, I do begin to understand them and am plucking up the courage to have a go at initiating them.  First job is to build a test rig (good suggestion Dave) and this is underway.  Second job is to decide which channels to mix with which.  With my existing Spektrum dx 6i, I only have two mixes available, as 'clockworks' noted, so I think I could add the 'spinning on the spot' modification to the left stick left/right command (mode 2, i.e. rudder on an aircraft) by slaving the port and starboard ESCs to the left stick left/right (aircraft rudder), retaining the P40E for normal mode 2 running, meanwhile learning the characteristics of the P40E so it isn't quite so wild under normal steering inputs.  During such manoeuvres under control of the left stick left/right, the middle motor would remain stationary. I am sure I can also modify the present throttle curve so that the boat is not so sensitive to throttle input at low speeds.  I think this is all possible, but as all transmitters seem to only understand aeroplane or helicopter controls, it might be quite tricky to achieve.  Isn't it about time radio manufacturers admitted that model boats exist and add a boat alternative to the menu?
Now, the alternative to all this is to buy a new transmitter with more mixes.  This would give me the opportunity to really play about with my new test rig. 
I think what is needed is rudder-directed throttle response on the port and starboard motors (replacing the effects of the P40E) controlled by the mode 2 throttle stick (left stick up/down), requiring two mixes, plus left stick left/right directed response to port and starboard motors (as Dave has achieved) controlled by the left stick left/right action, requiring two more mixes.  To this end I am presently after either a dx6 (5 mixes available) or a dx9 (10 mixes available but requiring a mortgage to purchase).
So, there we are, that's the current situation, but only arrived at by your encouragement and support.  I would really like to see both the Vosper and the Whaleback performing as they should, so I am determined to do whatever it takes to sort out.  Time to get on eBay I suppose.
Thanks again for your help, I will let you know the results eventually.


Regards,  Chris.

[clockworks]

Buying a new transmitter with more mixes is probably going to be the best bet in the long run, even if it costs you more to get these 2 boats working as you want. With a more flexible transmitter, you won't need to buy any extra hardware for future models, and you can get them all working exactly the way you want with a few button presses once you get your head around how it all works - it can be a steep learning curve!


How "locked in" are you to your Spektrum kit? Might be worth looking at other manufacturers' equipment. Some of the Chinese brands are producing good kit at relatively low prices now. I know that some forum members are using FrSky radios, but I've never seen one myself.


I still have a Spektrum DX6i to use with my crawler, but I ripped it apart and fitted the electronics into an old KO Propo wheel transmitter with some extra buttons and switches.


I got into using Futaba for flying, as that was what the guy who taught me used. The Futaba T7C that I've been using for boats is about 12 years old I think, and works fine. I've got about 12 Futaba-compatable receivers, so when I wanted a more "powerful" transmitter, I decided to stick with Futaba. Genuine receivers are very expensive, so I just buy them secondhand (half price), or use a Chinese clone.
I found a secondhand 14SG on eBay, for £205.  Best price I could find for a new one was more than double that. It should do everything I will ever need for a boat.


As for why the manufacturers don't make boat-specific "computer" radios, I guess the market is just too small for them to bother. Most of the guys at my club are perfectly happy using older, simpler, radios. They only need 2 channels, and to some of them a servo reverse switch would be a luxury. Seems crazy to me that they spend many hundreds of pounds and months of work building boats, then use a £20 radio without something as basic as model memories to sail them.


Pretty much the same with radios for use with cars - if you want "computer" features, you have to buy a wheel radio, or use one designed for aircraft.

[Big E]

I must admit that the reason I am thinking Spektrum is that I have a friend who is a radio wizard, and although he suggested replacing my dx6i with a dx6 to give me the necessary 5 mixes, he is also strongly recommending the dx9 to give me more channels AND 10 mixes.  He is convinced that I will build more complicated models in the future and that I might even consider turning to "the dark side", aircraft! Who am I to argue, especially as he is the one who has solved my radio problems in the past.  He is away at the moment, so I am struggling to make sense of my problems by myself, hence my calls for help to MBM.  Success, you and DJW have been more than helpful.  Besides, I really ought to be able to master a radio tx myself, I'm just being lazy.
Anyway, I will look at other makes and reviews and report back.  Thanks for being so patient and helpful, you've given me the determination to keep trying.
Incidentally, I've just tried to turn on my tx after unsuccessfully trying to bind it to the Whaleback.  Blow me if it won't even turn on!  Definitely time for a new one.

[JimG]

If you are looking for a new transmitter then you should seriously consider the FrSky Taranis. This uses the OpenTx operating system and is completely open as far as setup. There will be a lot more work involved in getting the controls you want but as far as mixing controls the sky is the limit.
Jim

[Big E]

Thanks for the thought Jim and I had previously had open tx suggested to me, but it's just a step too far for me. I know it's capabilities are limitless, but that is more than you can say for my capabilities!  Maybe one day, after all, they are much cheaper than many transmitters.


Chris.

[Akira]

Chris, Don't be put off by Open TX. This is coming from someone who, just this year, bought his first 2.4g radio and it is a Taranis. It is my first computer radio and,all independently, I still am doing long math with a pencil and paper! LOL. No only is the radio intuitive, but there are numerous video series on YouTube that take one by the hand and very clearly explain how to get from point A to point B without having to call Emergency Services to help you find out where you are.I am using mine on a destroyer, a PT boat, an icebreaker and soon another destroyer. The mixing in indispensable, both for throttles and animation functions, not to mention being able to set servo slew speed and end points,all independently, all without buying and installing extra hardware. Lastly, the ability to do so on so many models saves many $'s in hardware costs. (my apologies to those selling such hardware, I loved it when that was the only choice.I do really like the Taranis(does it show?), but there are other radios that use OpenTX so I don't think you are restricted there.Jonathan

[DJW]

Hi Jonathan and all


I commented earlier on this thread about my tweaking of a Futaba 6EX system to get the mixing needed for my Aquarama, I pretty much managed it but now I'm running out of channels for operation of lights / vapour and so on.  So I'm going for the FrSky Taranis Q X7S paired with a FrSky Archer R8 Pro RX.  I really like the flexibility it offers and the price is very good for the functionality.


Regards to all.
David.

[Akira]

David,
best of luck. I am sure that you will enjoy it.here are a couple of links to help with your Taranis set up.https://www.rcgroups.com/forums/showthread.php?1914834-FRSKY-Taranis-How-to-Threadhttps://www.youtube.com/watch?v=WpYO7HkjxGQThere are many more videos on YouTube that make the radio set up quite easy. I have found the manuals to be quite useless.cheersJonathan

[Akira]

Sorry, but there are two links in my last. Sleepy fingers.