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Dec 10, 2017, 05:05 AM
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New EeZeBilt - free plans for an OSA Missile Boat


A bit off-topic, I know, but I have few places to advertise, so I thought people might like to know that the 'updates' to the 1960s British 'EeZeBilt' starter kits are still continuing. The latest offering is a Warsaw Pact OSA -1 Missile Boat - actually the export version that went to India in the 1970s.

Free plans, instructions and a rather abbreviated (I lost a lot of pictures) build log are available here: http://eezebilt.tk/OSA.html At 32" it's rather large for an EeZeBilt, but that makes it look more impressive.

Now you no longer have to sail boats with Western navy flags on the lake! Take out a boat with Somalian, East German or North Korean markings, and scare all the other sailors!
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Jan 17, 2018, 07:13 AM
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Very nice Dodgy. Can you tell us what motor and components you used?

I've been a fan of your site for a while and have been tinkering around with ideas for a design to contribute

Jon
Jan 17, 2018, 04:42 PM
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it has a 35mm brushless in it - I got a set of them cheap from a closing-down sale. That's probably over the top, but I wanted to see what it was like.

I'm rather busy with work at the moment, so I have little time to model, and for some reason I mislaid the battery and radio I was going to use, so I have not even had it in the bath...er.. test facility to trial it.

The prop-shaft and rudder are made up from piano wire and brass - much cheaper than buying one! The servo is a cheap little 9g TowerPro one and the battery (when I find it) is a standard 6 cell nimh 7.2v. The boat was designed to just fit that across or lengthways - in fact two might be needed to give the boat a bit of weight. Both the main mast radar and the gun-laying dome rotate - again easy to do with cheap geared Chinese motors because there's lots of room in the superstructure.

I hope I can get it completed when work is not so frantic, and get some more shots of it in action. For some reason there seem to be very few of these about - perhaps no one wants to fly the North Korean flag on the boating lake...?
Jan 18, 2018, 07:13 AM
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Quote:
Originally Posted by dodgy
The prop-shaft and rudder are made up from piano wire and brass - much cheaper than buying one!
Yes, I was really taken with the simple fabrication methods shown on the website.

I've not built a propshaft yet but I've been experimenting by cutting down a Tiny Whoop quadcopter prop to make a 20mm marine one. It's a push fit on a 0.8mm shaft so would maybe suit piano wire. The only issue is it's a tractor so the blade camber is wrong with the hub facing aft.

The other pic is a conversion of the innards of a HXT500 servo to give a micro ESC. I might have to try it in one of the smaller Eezebilt designs - or scale one down
Jan 19, 2018, 03:44 PM
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The prototype EeZeBilt kits came with a propeller, shaft and tube that was (presumably) built using the light workshop technology of the 1920s-50s. A simple stamped tinplate prop soldered onto a steel shaft and put in a brass tube. Instruction on how to make an exact copy using scissors, a drill and solder are HERE. I suspect that original manufacture was not that different!


It can be improved using a larger brass tube with two smaller tube segments soldered in the ends acting as bearings.


For the larger boats I have taken to using similar manufacture. A 4-6mm brass tube can be plugged at each end with a brass cap with a 1/8” or 3mm hole. While I use a lathe to turn out well-formed caps, you can make a perfectly acceptable one by drilling a scrap of brass, then turning it in a drill with a bolt through the hole and using a file to shape it so that it fits in your tube. Making one out of Nylon is even easier.


I use commercial-bought M2 or M4 props, and cut a thread on a length of piano wire for the shaft. That’s the only tricky bit – piano wire is the wrong material and is quite hard to cut even after softening the end with heat. Ideally, I would use a softer steel – but piano wire is cheap….. if my small boats had room enough I could use dog connectors and then buy really cheap plastic props…



You should be able to reverse your props by cutting off the ‘spinner’ end, then creating a new one out of filler on the opposite side….


I have occasionally heard of using servo electronics as ESCs for very small boats. Do you actually get variable speeds using this, or is it a simple switch? I found a set of very cheap small brushed ESCs on ebay, so I bought a lot and have not got through them yet. I found one problem to be low voltage operation – small motors sometimes only want a few volts, and the radio wants at least 5v….
Jan 20, 2018, 07:59 AM
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Originally Posted by dodgy
Do you actually get variable speeds using this, or is it a simple switch? .
Yes, you do but there's not much deadband in between so it's hard to totally stop them. I find that if you put the throttle channel on a sprung stick and use some expo they work just fine. One potential issue is that the motor is taking current through the receiver so there's a practical limit to the size of motor you would want to use this for. I was considering using it to run a small coreless underwater as direct drive to make a tiny outboard for a reduced size Cresta

Quote:
Originally Posted by dodgy
I found a set of very cheap small brushed ESCs on ebay, so I bought a lot and have not got through them yet. .
I did try one of the 10A ESCs from Banggood (the ones recommended on your site IIRC) but they aren't compatible with my Spektrum gear (the reverse doesn't work.) There are some others I haven't tried yet.

Quote:
Originally Posted by dodgy
I found one problem to be low voltage operation – small motors sometimes only want a few volts, and the radio wants at least 5v….

Running receivers on 1S is no problem for most of them. We've been doing this is gliders for years. It may vary from brand to brand but the brown out voltage of most receivers is 3.0-3.3V. As long as you have a decent capacity lipo you run out of juice well before the rx dies. The other option is to add a cheap voltage booster to give the receiver 5V.
Jan 21, 2018, 08:54 AM
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I was considering using it to run a small coreless underwater as direct drive to make a tiny outboard for a reduced size Cresta...

I had been playing with making them drive small torpedoes for the EeZeBilt PT boat - but it was hard to make them stay at the right depth. Mind you, that would have exactly matched full-sized practice...

I did try one of the 10A ESCs from Banggood (the ones recommended on your site IIRC) but they aren't compatible with my Spektrum gear

Oh dear! Sorry about that ! They seem to work all right with cheap radios - I use the RadioLink range, as you can see...
Jan 21, 2018, 09:39 AM
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No, don't worry - they do say that on the bangood site. I didn't buy one but had the opportunity to try one belonging to a friend
Jan 21, 2018, 06:36 PM
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I'm ever so sorry - I owe you an apology! I've just looked and it wasn't the ESC recommended on the Eezebilt site - I must have got that from somewhere else
Jan 22, 2018, 03:45 PM
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Ah - that saves me from having to update the site... on a happier note I( have just added the USS Missouri battleship to the Old Boats site - 56 inches of firepower from Sterling, courtesy of Paul Sluce...
Aug 17, 2019, 06:06 AM
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OSA missile boat


Currently building from your plans. What happened to former F6? Missing from pdf file . Some of the instructions are a bit confused. I'll get there in the end . Will go through and send corrections. Will cobble F6 together.
Thanks you for all the trouble you have gone through putting all these plans together.
I've built from scratch many boats and plans but i am enjoying the challenge of this one.
Thanks again. Will post pic and video when finished
regards
Bob Wells,
tried to pm you but your inbox is full
Aug 17, 2019, 08:37 AM
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OSA missile boat


Hi ,
Apologies! Just realised what former F6 is! Sorry.
Aug 22, 2019, 08:29 AM
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Sorry for not replying sooner - I've been travelling. Now I'm back, I'm recovering!

Will be back on the boards reasonably soon. In the meantime, please do point out errors - it's the only way I can get an independent check on things... and photos for the site would be great.

Incidentally, I found that the construction process leaves the transom rather unsupported, and I managed to build a twist into mine. I suggest either adding some sides at the rear, or building on a flat board. I should really modify the design to remove this problem...
Last edited by dodgy; Aug 22, 2019 at 08:51 AM.
Aug 22, 2019, 01:21 PM
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osa missile boat


Got the formers mounted and working on superstructure. Cant do anymore on hull till motor is mounted.
will post pic and video when finished.
regards
Bob
Aug 22, 2019, 02:25 PM
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I'll look forward to seeing it! Which nationality do you fancy kitting it out as?


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