It's entirely possible that the antenna is a dipole.

If you look at the picture attached which is the anatomy of a "rubber duck" antenna you can see that the wire going into the bottom of the black plastic is coaxial (non radiating) and the 2 poles of the antenna are 180 degress apart from each other.

If you apply this concept to the FlySky antenna it is plausible (likely) that the thicker red part is the 2nd pole and the thin wire at the end the other pole

A scapel would confirm 😊

Regards

Jonathan

Re aerial length. A single whip antenna can be brought to resonance when it is only a 1/4 wavelength PR about 3.5 cm at 2.4 GHz. The next best would normally be 3/4 wavelength.
Any length can be made to work with tuning.
But its a bit like a tuning fork.
One end is fixed and the other end gets hit and goes to and fro. And that, in nature, happens at multiples of 1,3,5 etc of quarter wavelengths

Hi Doug, I have just measured the aerial wire from the box to the tip which is hidden inside the red tube and it is 144mm . This is the same on both of my flysky units.
Cheers Colin.

I did a lot of RFI work. The whip antenna was always tuned to resonance using an aerial tuning unit. But it remained unidirectional, which is what we want.
The crude equivalent is a loading coil at the bottom of the aerial. You see similar on the roof of some older cars, a sort of spring that can double as an aerial support. For us, the value of that would be fixed at manufacture so no need to worry about it.
The point of tuning the aerial to resonate at the required frequency is that wanted signal increases and interference then gets rejected by the aerial circuit, so the rubbish does not get in by that route. Which is ideal. But as remarked earlier, gremlins creep in by any gap, just like a rat...

When I read all the highly technical stuff about radio and the associated complications on here, it makes me realise how lucky I am to have Alice who when I finish the building of a boat just gets on and does the radio and electrical bits. She knew nothing about models until I started building but built TV sets and computers when she was in school and passed her amateur radio licence exam when she was 18.

Cheers, Nerys

"somebody told me that the extra thick part of the aerial was a booster,"
Booster! My left big toe!
As far as I can tell from your photo the wire coming out of the RX case is the usual single core stranded wire like all other RC RX antennas.
Thus the most that that thick bit could be is a kind of passive loading coil for impedance matching and/or adjusting the effective electrical length of the antenna to the wavelength of the frequency band of interest, e.g. 2.4GHz, 12.5cm wavelength.
But why? When the whole length seems to be near 12cm anyway.
What is the actual length from the antenna case to the tip of the red bit?
In my opinion that 'thick bit' is simply a joint between the flexible wire and a stiffer upper part inside the red covering. So I stand by my previous post😉
Make the vertical part (the piano wire) about 6cm, which approximates to a scale VHF IMM Marine band whip antenna, and the horizontal part in the cabin roof also 6cm.
Then you have the best of both worlds; vertical and horizontal polarisation!
I note that the rubber duck antenna on the TX is on a ball joint so you can position it vertically, horizontally or anywhere in between. So there's most likely no second horizontal antenna in the handle.
Always keep the axis of the TX antenna at right angles to a line between you and the boat. Never point the tip of the antenna of the boat, although it may seem logical to do so it ain't.
Why?
The maximum signal is radiated, in all directions (omnidirectional), from the centre of antennas of this type. Virtually nothing comes directly out of the end of the antenna.

Ref the 'Booster': there are only two ways to boost, i.e. amplify a received antenna signal or increase the sensitivity of an antenna.
1 An RF amplifier in the RX immediately after the antenna input.
2 Antenna shape and dimensions to provide antenna gain, with respect to a simple omnidirectional wire or rod/whip. This always makes the antenna directional, i.e. it needs to be pointed at the TX to receive the maximum or nay signal.
The most common version of this is the Yagi antenna.
Nip outside and take a look at your TV antenna, that's a Yagi.😉
A central carrier with a number of short elements at right angles to it. These are the actual receiving elements. The more elements there are the higher the gain wrt the simple whip, from 6dB to about 20dB i.e. times 2 to times 10 in voltage terms, but also the smaller/narrower the angle of reception, i.e. the more accurately the antenna needs to be pointed at the TX. Not terribly practical for RC models of any type; land sea or air!
The spacing between these elements varies slightly to enable reception of a specific bandwidth. At the back of the antenna you will see a reflector grid, looks like it's been nicked from someone's garden grill😋 it may be flat or bent into a 90° angle.
In front of that is a slightly longer element. This is the one that actually feeds the signal down to your TV. All the others in front of it are the so called guide elements which 'funnel' the signal along to the feeder element. That's where the antenna gain comes from, the more the merrier😊
Now you'll tell me that you only use cable or internet TV anyway and have long since removed the old TV antennas🙄 Anyway, I hope you've at least learned a little more about radio and antennas.
My first boss always called it 'A Black Art'! Gave me some leverage and freedom of action😊
I never made it to Uni. Came close to getting in to Liverpool but my pure maths A level wasn't good enough, although I got 1s in Applied maths and physics. Was always more practically minded than theoretical!
So I went to Twickenham College of Technology (closer to Mama Hotel in Staines😁😋) where I took a sandwich course,~ 6 months college / 6 months industrial training.
Learnt much more practical and useful stuff, that actually stuck, in industry.
My interest in radio was sparked by my Dad, he was an Electronics / Avionics Officer in the RAF and one of the first wave of radar technicians in WW2.
Funny when I think about it; what he used to do for aircraft, from Spitfires to the Victor Tanker conversions and finally MRCA Tornado. I ended up doing for all classes of naval ships, from Fast Patrol Boats and small diesel subs up to Light Fleet Aircraft Carriers😉
On the way I also spent some time programming the automatic test equipment for the Radio Type Approval Lab of the then GPO later Home Office, and the monitoring / scanning equipment that they used to survey the first Cellular Radio (mobile phone) sites in UK.
Happy times😊
Ramble ramble🙄
G'night all 💤💤💤
😎

I havethe same rudder as you and a standard prop shaft, however the prop sits closer to the rudder. I will experiment as I get more familiar with the boat and maybe change for a smaller diameter brass prop. that will not flex. Being old and plastic, mine possibly will flex under load.

All part of the fun.

I have the same radio and am using a 3 channel receiver. I have that, including the aerial, completely enclosed below a false deck in the aft cabin together with all the electrics. No issues at all and when out yesterday, I was approx 60m from shore with no issues.

The same with my other boats, also using the same Flysky TX units, the aerial is below decks with no issues. The transmitters have a great range and were well priced when I bought mine. Mind you, since Covid and the exchange rate change, they have almost doubled in price.

Thanks Doug, yes only 1 wire out of the flysky rx's that I have, somebody told me that the extra thick part of the aerial was a booster, but nothing mentioned in the instructions booklet about it.
There is 26 mm above the thick section, none of the other makes of rx's I own have this type of aerial, most have either a single thin wire or 2 thin wires I even have one with a loop aerial ,but i don't have a tx for that one.(yet).
I wish I had Learnt something about radios when at university, but thats along while ago.
But having a reliable source of understandable instructions, from you makes it easier for me to get to grips with it.
Good night Fleet, cheers Colin.

Is that Luke Skywalker?
With him as pilot you can't go wrong👍
Watch out for the X-Wing hydrofoils though😁😂🤣
May The Force be with you both🤞

Aerial:
First off; DO NOT PUT AN AERIAL WIRE INSIDE A CARBON FIBRE TUBE😮
Carbon is conductive (that's why it's used for motor brushes etc😉) and will effectively screen your aerial making your RX deaf!
If you want to use that peculiar red thingy just mount it so that it pokes through the roof and paint it white or silver.
Otherwise you can just chop it off and use the piano wire etc as described, which would be more to scale, maintaining the 12.5cm total length, OR whatever the length of the original is from the case to the tip of the red bit.
The 'red bit' seems to be only the end of the wire sheathed in heat-shrink or plastic tube.
Do the instructions say anything about the TX having two aerials?
One being the rubber duck for vertical polarisation and the other built into the handle for horizontal? If so install the RX aerial so that half (ca 6cm) is vertical, e.g. the piano wire, and half runs horizontally inside the cabin roof.
The RX only seems to have the one aerial wire?
Cheers, Doug 😎

And re the aerial as a flagstaff. In some parts of the UK, radio amateurs needed planning permission for their aerials. But not for a flagstaff....

The star wars figure sounds fun! But on a similar note, figures in 1/36 or at a pinch 1/32 seem incredibly expensive and in short supply.
Do I feel a 3D printer coming on? Can anyone suggest a source of basic figures that does not cost the earth?

Grandson gave me a star wars figure to use as helmsman today.
I've also managed to start rebuilding the cockpit window.
The flysky radio set will be the one for the job. I have read the instructions and it seems that I only need the top 30mm of the red aerial unit to be outside the boat.
Question for Doug, how would I go about disguising it, would your metal aerial idea work with this unit. I thought maybe to use a carbon fibre tube as a flagstaff with the aerial inside it.
Cheers Colin.

Rudder to prop position??
I believe that would depend on shape and type of rudder, most of my vintage boats have standard shop bought brass rudders which seem to be between half an inch to 1 inch from the prop.
It seems like all the ones at 1 inch are the ones with a water pickup between prop and rudder.
Surely your rubber seals wouldn't work very well on high speed shafts.
Using Teflon washers allows the thrust of the prop to stop water ingress. And the same on the motor end will seal it when in reverse. I allow approximately 10 thou end float.
Both of my commanders have 40mm brass 4 blade props.
Cheers Colin.

Yes, I have glazed the windows and maybe was a bit exuberant in my turns. I do think though that the issue is the prop tube. It is sealed each end with a rubber grommet however these could be better. I assume the tubes would suck the water up and will see if i need to top up the marine grease.

Question for you, what is the optimum distance between the prop and the rudder?

With the placement of my motor and the length of the prop. shaft I have to have the propellor roughly a half inch from the rudder. Get too much closer forward and it strikes the hull. I have a 3 blade plastic prop. Thanks.

Looks nice and level, I think you may get wash over turning at speed, are your windows glazed.
That's a lot of water in such a short run check your prop tube to prop nut seal, i use a talon washer each end, I also fill the tube with marine grease .
Cheers Colin.

Colin, no decent photos but have put one up. Sits well in the water and comes to the plane very easily.

Took 1/3 cup of water in about 5-6 minutes so will have to investigate the prop shaft seals as that is the only way i can see for ingress.

I know, I was thinking the same. The only difference was that my battery was vertical which should nI ot make a difference as it is a weight issue.

I could have laid mine down by removing a brace i had put on the back of the tray i built but I had secured it too well.

Good try, she planes very well and I only have to work out what endurance i will get with the battery & 700 brushed motor. I expect better than 10 to 15 minutes but have also been told the motor is very power hungry. Maybe next time a brushless and LiPos.

Probably primarily designed for aircraft Colin.
But, as long as your boat is not made of metal and the RX is well above the waterline it should still work.
😎

But surely if you don't have external aerials then it will limit the useability in side a boat.
Cheers Colin.

Nicely done shipmate, how does it sit at standstill and low speed.
Cheers Colin.

Ooh er!😮 Did they drop off in the post Ian🤔
Interesting.
I have a stock of Spektrum AR610s and Tgy i6 RXs so haven't bought any for ages.
I can only assume that they have started using the PCB tuned Stripline technique that we were using for professional UHF personal radios back in the 70s. Police, Fire and rescue Service etc.
Wonder what took 'em so long to reinvent that particular wheel?
Cheers, Doug 😎

Hi Peter glad you came right.
Funny Mine planes like that with the battery forward of the motor!👍👍

Just a remark, the new Flysky and Spectrum 2.4Ghz receivers don't have any wires outside the case!😊😊

Supplement to antenna!
I've noticed that some RXs have a much shorter antenna wire.
These appear to be tuned for half wave reception, approx 6.25cm.
They may also have a coil inside the case to make up the total effective length of 12.5cm.
Whatever. The same principle applies. Keep your whip antenna total length the same as the original length of wire outside the case👍
Enjoy your reception Colin, slurp a glass of champers for me😁😋
Cheers, Doug 😎

I managed to locate my existing 4.5 amp battery under the cockpit by raising the deck 3/8 inch. Put the electrics below the aft cabin. Took it to sailing today and cracked the champagne. Very happy and what a difference that made by moving the battery back. Only issue is that I forgot to top up the battery first and only had about 5-10 minutes on the water. Better luck next week. A few images attached showing the improvement.

Thank you gents for your assist in this build. A few small fixups plus a windscreen to keep actionman dry and I will be ready for the next build - if allowed.

"then drill a small hole and fit a tube for the aerial."
RX position sounds good Colin👍 as long as you have easy access to the servo / ESC plugs!
But rather than a silly looking tube why not make it look like a typical VHF Marine whip antenna? A length of 1mm piano wire (with a safety knob on the tip!), brass fitting as a through connector with the antenna wire from the RX soldered or screwed to the end inside the boat.
Just make sure that the total length remains the same as the original antenna wire.
Approx 12.5cm.
BTW: does your RX have two antenna wires like most these days?
If so run the second wire along the inside of the cabin roof so that it is at 90° to the roof antenna, i.e. horizontal. Then you have two possible reception routes and the RX will always automatically use the one providing the strongest signal - so called Antenna Diversity😁
Cheers, Doug 😎

Hi Colin,
Glad that some lubrication improved things😊
Also, loading the prop in the water will limit the revs, dampen any hull resonance and hopefully reduce the noise to the classic Taycol growl, not unlike a small marine diesel😉

Seaman Cook is right about alu foil not necessarily improving matters.
In fact it can make things worse as the interference waves will rattle around reflecting off the foil and meeting and interfering with each other. Sometimes they will meet out of phase and cancel each other out.😁 Sometimes tho they will meet in phase and add together to increase the amplitude🤔
Just like the effect on an FM car radio when driving around town; you may get stopped at the lights and the radio gets very noisy. Shunt forward a few feet (without poking the car in front😮) and the signal clears up again. This is known as the Rayleigh effect, after the engineer who discovered it.
Alu foil could only help if you make a Faraday cage out of it which totally encloses the motor, with ferrite rings fitted to all wires which go in and out of the cage. Not very practical!
SC is also correct when he says that interference must be stopped at source.
Hence the capacitors on the motors should be connected with the leads on the motor terminal side as short as possible. The other side should also be short and the motor frame (or can) earthed via the propshaft tube, as you have done👍
BUT: as I said the diodes in the bridge in the converter box already suppress the brush sparks quite effectively. The capacitors are simply a belt and braces precaution.
When I first test ran your motor before converting it the brushes produced the expected fireworks display. Very pretty, and Oh that lovely smell of ozone😉
Now you should only notice a very tiny ripple of sparks on one brush, on the left looking at the motor from the connector end as I recall. Can be seen in my video of the test, but it's too big to post directly🤔 Careful adjustment of the brush carriers / tension arms, to maximise the contact area of the brush with the commutator disc, is needed to minimise this effect.

You COULD try making brushes out of carbon rod, with tiny holes bored in the end to fit on the carriers, but they will wear out much quicker than the fozzy-bronze and clog up the commutator slots with carbon dust. Also the skin effect SC mentions will come into play whereas it is not a problem with the fine mesh of the existing brushes.
BTW: skin effect is the reason why we should always use multi-strand wire to connect our motors and ESCs, rather than a single thick wire.
I have queries about some of the other comments from SC, e.g. 'big capacitors' and introducing inductance, but that's for another day!
Beddybyes time now 😴💤
Cheers, Doug 😎

If you suspect motor interference is an problem, one has to stop it as near the source as possible. That means on the motor. At these frequencies the electricity travels on the surfaces, not in the material. If you have a hole in a bucket clearing the mess is harder than plugging the hole....Foil will have only a minimal effect, and might make things worse. I can make and supply the filters I describe to any reasonable size at least 30mm diameter and 15-20 mm high.
Before one spends money just see first if anyone complains.

I've been looking at my layout and trying different ideas for the position of the RX.
Well I believe that I have found the right place, mounted on the underside of the rear cabin roof, then drill a small hole and fit a tube for the aerial.
That's the idea anyway, after the grandchildren go home tomorrow evening I will see if its viable.
Cheers Colin.

Thank you Doug, and seaman cook, extremely interesting though it is, I'm still an electrical moron. I can work with basic instructions and pictures, I can usually follow Doug's instructions, with care I manage to get there in the end.
You are right about the rotation being quieter in clockwise, I'll change my prop, also it is better now I've lubricated as well as adding some thin foam under the motor mount.
The noise is much less when in the water, just fits in baby bath.
My neighbour asked if it's possible to change the brushes to carbon.????
If I add a layer of baking foil to the bulkheads would that eliminate any spurious interference .
Prop tube earthed to motor chassis.
I am at present having a break from the kids while the wife has a play with them.
Cheers Colin.

Wow that is an impressive set of numbers. I'd love to have that sort of test gear, but my scope stops at 100MHz. May I add a little. I've spent many unhappy hours sorting RFI problems.
I hear what you say about not seeing anything that is near to 2.4 GHz.
Motor suppression with normal capacitors is chancy. There will be some reduction in noise, but a big capacitor can cause problems to the driving ESC, especially if it is an HF type. Does such a thing exist or are they all at below 200Hz? If very unlucky, a big cap can resonate with the switching edge and cause a blow up.
Another problem is the inductance of the legs. At fairly low frequencies the reactance and resistance of this can be larger than the cap. reactance....Google Skin Depth. And then that means there exists a resonant point. Worse, sometimes the lead length can approach a 2.4 GHz aerial length....
The fix is to use a copper clad PCB type material on the motor terminals. This is easily etched or ground out to take surface mount legless capacitors. If space allows, two small caps fitted pointing in opposite directions on each leg and joining to case is best, plus one across the terminals. Take off minimum copper, and use as much copper as possible as equal to the case. Any common grounds should be doubled as far alert as possible.
With such a PCB you can now add a small 2 winding inductor with the cap arrangement now repeated at the ESC end, but with smaller capacitors. Voila, you have made a proper RFI filter that will work into the GHz range. In extremis pay for GHz rated RF capacitors. But even the cheap 2p types will work well as they are all layered.

Hi Colin,
Re "Doug motor behaves well but extremely noisy in forward,"
If I remember correctly the motor was inherently happier when rotating clockwise, when seen from the output end, i.e. looking from behind the prop.
Remember; the old Taycols always did growl a bit😉
Also, it's been perhaps 18 months or so since the motor last ran on my test bench.
It growled then, and complained with an extra loud growl when, after the conversion, I abruptly switched it from forward to reverse or vice versa. But rapidly settled down to a subdued growl.
I have a video of my final bench tests and running in, but it's 93MB😮 so not easy to post.
I'll see what I can do about that.
You probably also need to oil the ball races I fitted and also the brush gear!!
Don't forget that the brushes are not carbon but wound copper mesh and need frequent lubricating.
Do me favour please, try running the motor with that UJ coupling disconnected.
I've stopped using them cos I find them noisy in themselves.
I now use one piece flexi-spiral couplings. See my Sea Scout restoration blog for details and pics. If the motor is then significantly quieter check the shaft alignment and the amount of fore and aft free play in the coupling.
Ref interference:-
What CB90 writes is quite correct - for a standard Taycol without the conversion I did.
Especially if the brushes have been run dry, i.e. not oiled.
However, my test video clearly shows that the diodes in the converter box effectively suppress any sparking at the commutator😉
Also in my Sea Scout blog you can see, with video of the scope traces of the brush gear voltages, the difference the same conversion made to the Taycol Target that Dad had originally fitted in the Sea Scout.
As 'belt and braces' you could fit a 0.1mF capacitor across the brush connections and 0.047mF from each brush to the motor chassis (frame). Also connect the motor frame to the prop shaft tube to earth it into the wet stuff.
CB is also correct that spark interference should not affect 2.4Gig radio sets.
This is true for interference received at the antenna BUT if the RX is too close to the interference source, i.e. motor, it may directly affect the internal RX circuitry, i.e. the lower intermediate frequencies used to down convert the 2.4Gig RF to something that the decoder can work with.
Just like an FM radio down converts the 88 - 108MHz RF to something that our lug'oles can cope with😊
The peak spark interference is in the LF/HF bands (up to 30MHz) and tails off significantly in the VHF and UHF bands and is insignificant beyond a few hundred MHz.
BUT: it can still affect 40MHz sets - such as still used by submariners, like me for instance, cos 2.4Gig doesn't penetrate water. It just tries to warm it up, just like your microwave oven heats up your nosh! So motor suppression is still needed in case a model sub is operated near your boat!
BTW: I conducted all the bench tests on your motor using both a servo tester box as well as my 40MHz Graupner MC-10 radio.
Cheers and good night, Doug 😎😴💤💤

Thanks CB,
This motor used to work fine with my old radio kit, 27mhz and 40mhz.
Now after Doug rebuilt it for me, and added the converter box for reversing, I have decided it would be better to upgrade my radio.
Its just a matter of positions the rx .
This boat is one of 2 sea commanders that I own and is rather special to me as my dad built it in the late 50's.
Cheers Colin.

Hi Colin,

The old taycol motors can be rather electrically noisy giving off interference, I would worry if you were using 27mhz, but a modern 2.4 ghz should be ok.

http://taycol.tk/index.html

Update on my refurb, I have installed the esc, taycol converter box and rudder servo.
Now I need to find the best place for the reciever.
Had a bit of accident and broke the cockpit window frame, so will have to remake again.
Did a test on the installed items using my servo tester and (Doug motor behaves well but extremely noisy in forward, I am looking at swapping the prop for the opposite rotation) all is working as expected.
Any suggestions on position for rx would be welcome, I'm using a new 2.4ghz set. I did think under the dash as that would allow the aerial to come up the cockpit window frame centre support. But I'm worried that it will be too close to the motor.
Cheers Colin.

Hi Ian and Peter,
My 12v7ah batteries weigh in at 2.218kg and are 150mm long x 95mm high x 63mm wide and lay nicely on my styrene pads to clear prop shaft, still fit below the deck supports.
The motor and mount weigh in at 462grams so I don't think I will need any further ballast.
Cheers Colin.

I will weigh my battery

Thought so, I tried again today only this time put approx. 600g under the cockpit. It did make a small difference before i had an electrical issue. Luckily one of the guys had his pusher tug and was quick to the rescue.

Easy fix and will see how it goes next trip. Getting a lot of attention at the club and all of a sudden more old designs are coming out of the woodwork.

Hi Peter,
My SLA does lay on its side in a tray 4.5Amp Hour Dimensions 90 long x 70 wide 107 high.

And it would last a lot longer. I will investigate. Thanks.

Hi Peter, the 7ah version is slimmer but longer than the 4.5ah so fits under the deck easily.
Cheers Colin.

Hi Colin, I tried that yesterday so would have to raise my deck levels. No great job and might be something I have to attend to. All fun in boating...

Just checked, definitely 4.5....Weighs in at just over 1kg. I do have to admit, yours does look smaller.

Hi guys, sorry I've not been on lately, but have been keeping up with your progress. As for the battery position as I only have sla batteries available I used a 12 volt, 7 amp hour. Located under the open control deck, laying on its side on top of styrene packers.
Cheers Colin.

My Battery is half the size of yours, 4.5 A/H compared to yours at 7A/H

Hi Ian. Exactly the same location. This afternoon i looked at putting it under the cockpit floor but would have to raise that due to the prop shaft. I may go back to putting a piece of lead in the stern.

Looking at yours, the battery is laying down whereas mine is upright. Should not make a difference as it is a weight issue. I have it very secure with and does not move laterally.

Just Checked my SLA is a 12v 4.5A/H and sits in front of the motor see picture (ie towards the bow). Where is your battery located?

Thanks for that. Auto paint and apparently a Ford green - Much to my sons disgust. He is not a Ford enthusiast.

That is good. I might try relocating back under the cockpit and see what happens. Do not want to put extra weight in. Will check out on Friday.......