First timer help please

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First timer help please

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31 December 2016 at 11:27 #69193
Rumration
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@rumration
Hi to all,

I am about to embark on my first ever boat build. It's an Aeronaut Pilot. As I peruse the project ahead, there some things I need your help with please.

ŶIt's a twin screw, so do both motors rotate in the same direction, or opposite, and do I need a left and right propeller for either? I think left and right for opposite rotation.

Secondly I Have both a spectrum DX 6i, and a DX 9, I can use either. Now I'm assuming you boaters have your throttle stick in neutral at the centre of its movement. When I fly my aircraft it is obviously at its lower position, as I do not require any reverse function. So I'm just wondering which is the best way for me to set up this stick. Do you have a auto spring return to neutral, or just fiddle about until you find zero revs?

Final question for now! Brushed or brushless. Does it matter, apart from the motor efficiencies.

Hope you can kindly advise,

Kind regards,

Glyn.
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31 December 2016 at 11:27 #2640
Rumration
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@rumration
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31 December 2016 at 12:57 #69197
ashley needham
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@ashleyneedham69188
Hi Glyn. As a general principle it is best to have the props counter-rotate (ie one goes clockwise, the other counterclock) as this will help the steering.

Secondly, brushless seems to be the way to go nowadays, and for this size of boat I would say a 28mm outrunner would do the job, Kv depending on your battery voltage, but something in the 1000-1300 range would probably do. There is no hard and fast rule as to what Kv or size of motor is required, at present is personal taste. Speed of prop rotation depends largely on how fast you want to go and how large a prop is going to be fitted. On a 2s or 7.2 Nimh battery a motor(s) as suggested will turn up to a 40mm prop easily at between 6000-9000 rpm which is a decent rate for brisk performance depending on prop size and so on.

Thirdly, if reverse is not required then an aircraft type ESC can be used, and these are very cheap (get a program card for whatever make of ESC you get…even better,use an ESC of the same make as installed in your aircraft), and the throttle would then be set as per your aircraft use, ie at the bottom.

Good luck, Ashley

Edited By ashley needham on 31/12/2016 13:07:56
31 December 2016 at 13:29 #69198
Dave Milbourn
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@davemilbourn48782
Glyn

Firstly here's an article about controlling twin motors **LINK**

Your transmitter will need a spring-return for the throttle stick to make sure that the motors stop when the stick is centred. If you use split throttles (i.e. two sticks) then both will need a spring-return.

Most people use counter-rotating props on twin motors; usually the starboard prop rotates clockwise when viewed from the stern.

CMB suggest using two MFA 380 motors with 7.2v NiMH packs. I'd go along with that. You can always refit the model with brushless motors and ESCs later if you wish. They are more efficient and will make the model quite a bit quicker, but you might chose to learn how to steer the model first before you start breaking speed records with it!

Dave M
31 December 2016 at 16:10 #69202
Rumration
Participant
@rumration
Hi thanks for your replies. I can see that contra rotation is preferable so a left and right handed props requires. I'm going to go with brushless outrunners as I have them and two ESC's in stock. I also have lipo's to run them with. That will, of course, save me buying NiMH packs. I also have 4, 6 channel receivers to hand and a computer transmitter, so mixing and throttle curves not a problem, (That statement will no doubt come back and bite me!)

I think the problem will be the ESC as I'm sure mine will not have a reverse function. So I will try a set up on the bench, if it works fine if not I shall try to find a reversing Unit that will work. If that fails I'll have to buy the whole shebang.

Anyway going to start the build tomorrow hopefully.
31 December 2016 at 21:28 #69209
Kev.W
Participant
@kev-w
If you sail on a purpose built pond, with access to retrieve the boat around the entire pond, you can do without reverse.

However, if like myself, the water you sail on is a natural lake, where access to a vast amount of the waters edge is impossible, then reverse is a necessity.
31 December 2016 at 21:37 #69210
Rumration
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@rumration
Hi Kip,

It will be a lake with a mile circumference. I have seen it, but not with any club members sailing. I have not met anyone from the club as yet. This is my local, and only club within a sensible distance. What happens if a model maroons itself out of reach I have no idea.

But I want reverse, just to learn handling and manoeuvring etc. If it's possible then why not have it.

Thanks, Glyn.
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