Second ever build – airboat

[Simon Anderson 1Participant @simonanderson1]

Cool – might give that a go next!

My next step was to add some epoxy resin to help waterproof the boat.

Edited By Simon Anderson 1 on 02/07/2022 17:07:17

[Simon Anderson 1Participant @simonanderson1]

And then once that was dry I put on a coat of grey primer:

[Simon Anderson 1Participant @simonanderson1]

Here's how it's shaping up with a primer coat on most of the boat. I'm not sure whether to glue the deck down earlier (i.e. before any painting) or leave it off in order to make any other adjustments necessary.. In this case I left it off for now and will attach later.

[Simon Anderson 1Participant @simonanderson1]

Starting to paint the deck in a dark blue – I'm using spray paint for everything at the moment, but I'm still far from being any good with a spray can – will need a lot more practice .. and then when you think it's looking ok some flies or leaves land on it !

[Simon Anderson 1Participant @simonanderson1]

… and here's how it looks now – main body of the boat is silver and the motor mount and rudders are white currently while the top is blue. The hatch cover I have painted in silver as well.

[Simon Anderson 1Participant @simonanderson1]

At this stage in the process the main thing I have been thinking is that it has definitely made this much harder by not having any plans or design to work from. For my first boat I used a printable skelton plan and it least defined all the key structural parts, but on this one I'm making it up as I go.

Other than decide to re-start from scratch with the main hull early on, the core of the boat has been pretty much ok, but the steering has been quite tricky for me on this build – I used an off the shelf rudder in the first one, but this one I cut and fitted from scratch which was much more difficult and very fiddly with hinges and so on. I also didn't really know where to put the servo so that it didn't interfere with the prop. Eventually I put the servo under the deck with the servo arm protruding slightly. I found it really fiddly trying to attach the servo arm to the rudder but I think it's working ok now – yet to be seen how it operates on the water though. Then I couldn't fit the deck back on so I had to cut a bigger hole to fit over the servo and now I need to figure out how to plug that hole.

I haven't got round to linking the rudders together, so the servo just moves one of them at the moment.

I also didn't realise the blue paint was gloss, so it gets fingerprints and dust all over it which can be quite frustrating to work with.

I think trying a kit would be a good option at some point to try and get some experience with tried and tested designs.

Some learning points that have come to mind:

• The primer improved the finish, especially on the 'deck'
• The build was much harder without any plan or design to work to
• Gloss paint is quite annoying as it gets marked so easily
• Not fitting the deck until after painting made painting the deck easier, but it was harder to fit and then adding servo meant I had to cut the painted surface and of course I scuffed it and it got covered in glue and fingerprints
• Spray painting is a skill that I need to get a lot more practice with
• I should have figured out the steering design before doing any painting

It looks "OK", so the next step is to see if it floats, and if it floats, does it actually "go"…

[Ray Wood 3Participant @raywood3]

Hi Simon,

I think you have been brave to do your own thing with the airboat, I think you maybe surprised how powerful the brushless motor and prop will be !! Ashley is the expert on boats with propeller's .

You could look up how aeromodeller's hinge the control surfaces on elevators and rudders to make a neat job with inset hinges or Mylar fabric.

Lastly you may want to turn the prop round, at the moment it will go really fast in reverse but not so well forward

Regards Ray

[ashley needhamParticipant @ashleyneedham69188]

Good spot Ray!

Simon, looking forward to seeing it tomorrow.

An extension to the bottom of the rudders in effect adding a couple of small water rudders makes a massive difference to usability and controllability in a breeze.

Peter will bring his airboat tomorrow won’t you Peter so you can see how that has been done. I’m bringing the Hobbies Hydro. AND the fireboat AND the gp1 paddle warship…..AND the ferry (as usual)

Ashley

i May bring the ULTIMATE to show Angela (but no one else and she will be sworn to secrecy)

[Simon Anderson 1Participant @simonanderson1]

Posted by Ray Wood 2 on 02/07/2022 18:36:59:

Hi Simon,

I think you have been brave to do your own thing with the airboat, I think you maybe surprised how powerful the brushless motor and prop will be !! Ashley is the expert on boats with propeller's .

You could look up how aeromodeller's hinge the control surfaces on elevators and rudders to make a neat job with inset hinges or Mylar fabric.

Lastly you may want to turn the prop round, at the moment it will go really fast in reverse but not so well forward

Regards Ray

Thanks Ray – I think doing this challenging project has helped me to improve in a few areas – and I was really keen to get it finished (good or bad) so I can learn from this one off and hopefully do a better job of the next one.

It could just be me not being able to set it up properly, but I don't think my speed controller goes in reverse, so whenever I accelerate it only goes it one direction (I can feel a lot of air being pushed back). I had noticed on some airboats the prop is pointed round the other way, and I still don't really know why that is the case on some airboats and not others. If the current setup is a failure, luckily it shouldn't be too much work to flip it around to go the other way!

Regards,

Simon

[Simon Anderson 1Participant @simonanderson1]

Posted by ashley needham on 02/07/2022 19:20:25:

Good spot Ray!

Simon, looking forward to seeing it tomorrow.

An extension to the bottom of the rudders in effect adding a couple of small water rudders makes a massive difference to usability and controllability in a breeze.

Peter will bring his airboat tomorrow won’t you Peter so you can see how that has been done. I’m bringing the Hobbies Hydro. AND the fireboat AND the gp1 paddle warship…..AND the ferry (as usual)

Ashley

i May bring the ULTIMATE to show Angela (but no one else and she will be sworn to secrecy)

Thanks – very good idea – I hadn't thought of extending them into the water – in my mind I was copying the swamp boats that can go across land/marsh and hence have to be basically flat bottom, but in practice I won't be doing that, so having something below water could be a good call if I decide to do any more work on this one.

I tried again linking the two rudders together and basically got stuck, so will be testing with a single rudder and see how that goes. I tried a piece of stiff wire through a hole in each rudder to connect them, but it seemed to only let me steer in one direction so I took that off for now. Aside from that, all the basics are there for a first working version to test out.

[Ray Wood 3Participant @raywood3]

Hi Simon,

Yes you will still get thrust from a propeller fitted backwards, but if turned round so the convex part of the blade faces forward ie to the front of your boat. so in fact a prop is only designed to produce maximum thrust rotating in one same direction .

If you meeting Ash tomorrow will explain what I'm driving at

I've been flying RC model aeroplanes both with tractor props at the front and pusher props at the back for 50 years trust me on this one

Regards Ray

Edited By Ray Wood 2 on 02/07/2022 20:26:32

[Simon Anderson 1Participant @simonanderson1]

Thanks Ray – I didn’t realise that – i had assumed that because I was getting lots of thrust it was “working”, but if I understand, the current direction will “work”, but it’s not giving the maximum amount of thrust for that prop.

Does that also mean that the airboats with props facing backwards then have a different type/convexity of the propellor so that works optimally ? And by the same logic if I had the other type of prop, it would work with the current orientation of the motor?

I will swap it round when I get a few minutes!

thanks again for the useful information.

[Ray Wood 3Participant @raywood3]

Hi Simon,

I think your over thinking this propeller business, there is nothing wrong with you motor pointing backwards, take the prop off the motor and put it back on the other way round, what's facing backwards now will face forwards, the rotation won't change and you have maximum thrust.

It's an old aeromodelling trick with an IC engine which is producing too much power to put the prop on backwards to reduce thrust.

Good luck

Ray

[Simon Anderson 1Participant @simonanderson1]

Brilliant – thanks very much Ray – I thought I had to turn the whole motor round! I’ve flipped the prop now – took 2 seconds and already I can notice the difference.

regards,

Simon

[Simon Anderson 1Participant @simonanderson1]

First test run today and key outcomes were:

– it floats ok

– it goes forward

– no obvious leaks or water inlets

– the steering doesn’t work at all (I thought maybe the single rudder would work but with the wind it was basically useless)

– the wind blows it away because it’s so light

Next steps are to attach the 2 rudders together and extend them down as mini water rudders to improve the stability.

thanks for all the suggestions and help so far – I think it’s almost there. Ironman struggled with weed today and had to be rescued.

[ashley needhamParticipant @ashleyneedham69188]

No chance really with the wind, but it showed promise and is as yet unfinished.

We had a couple of airboat things for Simon to look at to give alternative views on how to do…stuff…

Ashley

[Simon Anderson 1Participant @simonanderson1]

Thanks Ashley – and thanks to Pete and Trevor for bringing their air boats/tups for me to learn from.

I’ve tried a few alternative steering tweaks which haven’t worked so far. If I can’t get my current design to work I will probably start again from scratch with the steering mechanism. The main problem has been getting one servo to steer both rudders.

Edited By Simon Anderson 1 on 07/07/2022 19:31:56

[ashley needhamParticipant @ashleyneedham69188]

Simon. Glue a bit of very thin tube (upright) to rudders (say, bits 10mm long), at the bottom, on the insides, and link with a bit of bent wire. Operate one rudder with the servo. Easy.

Ashley

[Simon Anderson 1Participant @simonanderson1]

After the initial test run I took the feedback that it really needed a small rudder in the water to keep it more stable, so I cut out 2 small rudders and attached with a piece of metal rod to each of the existing rudders and lined them up so they pointed in the correct direction as the rudder above them.

At this stage I still hadn't got a working solution to the 2 rudders with one servo.

Edited By Simon Anderson 1 on 10/07/2022 18:54:41

[Simon Anderson 1Participant @simonanderson1]

I then tried to get the 2 rudders working together and added another small fin to the left rudder to attach a wire to.

[Simon Anderson 1Participant @simonanderson1]

I bent a piece of wire and put into the hole in each fin to start with. This worked to some degree, but only in one direction – the other way it just didn't turn at all.

[Simon Anderson 1Participant @simonanderson1]

I then tried a different approach connecting them at the back with a piece of wire. I ended up making a horizontal slit in the left rudder so the wire could move along it, and this worked to a degree, but it wasn't a reliable solution.

At this point I decided to abandon the double rudder design and try a simple single rudder design, and at the same time I would give me an opportunity to tidy up the mess of holes in the deck at the back of the boat and also to sort out the paint job on the deck as the blue gloss finish had become a bit of a mess by this stage.

[Simon Anderson 1Participant @simonanderson1]

These are a couple of photos after removing the rudder system, cutting out a piece of the deck and putting a new white undercoat down to cover the blue paint. I think it was the right decision to take the rudders off looking back as sorting out the paint job has left the latest version looking a lot better (at least comparatively!)

[Simon Anderson 1Participant @simonanderson1]

I then started from scratch with the rudder, this time using a thinner 1.5mm piece of ply that I had cut before for the rudder. I then followed Ashley's idea of glueing a tube to one side, but using a longer piece of tubing as it was the main pivot for the rudder rather than just to move the second rudder.

[Simon Anderson 1Participant @simonanderson1]

I then started work on the repaint job, going for a white, blue and red scheme, mainly driven by my limited selection of paint stock rather than anything else!

I painted the rudder first and was quite pleased with the new look (although I should have masked the entire middle section of white which I had to touch up again afterwards).

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