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Author Topic: Nixie  (Read 4211 times)

Andy M

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Re: Nixie
« Reply #25 on: January 24, 2021, 07:12:53 pm »

Someone mentioned Shark
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Andy M

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Re: Nixie
« Reply #26 on: January 24, 2021, 07:15:17 pm »

And a different one
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red181

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Re: Nixie
« Reply #27 on: January 24, 2021, 07:22:51 pm »

does it submerge though?
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TheLongBuild

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Re: Nixie
« Reply #28 on: January 24, 2021, 07:23:43 pm »

Can just see all the news reports now in your area  {-) {-)

red181

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Re: Nixie
« Reply #29 on: January 24, 2021, 09:28:36 pm »

bit more tonight, only prob is its looking too big! need to scale down the coning tower/fin! when completed, I know Jaws was big, but it might be too big sailing next to the boat!
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Andy M

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Re: Nixie
« Reply #30 on: January 24, 2021, 11:21:39 pm »

It doesnt submerge, the fin is carved foam. I was worried it would stick in the river bed. I did think about making it with sheet plastic sides instead with flood/drain holes
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Andy M

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Re: Nixie
« Reply #31 on: January 24, 2021, 11:23:06 pm »

It actually gave me a creepy uneasy feeling seeing it in the river, even though I knew it was just a model.
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Subculture

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Re: Nixie
« Reply #32 on: January 25, 2021, 08:44:02 pm »

If you want it to submerge it's best to make the fin hollow,from material as thin as possible, and free flooding.

This keeps displacement down reducing the size of the ballast tank or the speed required to submerge if you're making it dive dynamically

Fibreglass takes some beating, specifically thin cloth and epoxy resin. You could carve the fin from polystyrene foam, skim over with epoxy and a layer or two of thin 25g glass, and then melt the foam out with some acetone once the resin has cured.

red181

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Re: Nixie
« Reply #33 on: January 25, 2021, 11:24:29 pm »

Ill do my fin that way, I was wondering about exit holes though, so when it surfaces the water will escape?
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Re: Nixie
« Reply #34 on: January 26, 2021, 11:16:31 am »

You'll need a vent right at the tip to avoid trapped air. Minimum size hole 3mm (1/8") or thereabouts, or make a slot of equivalent area if you can't make a circular hole that size. Any smaller and water tends to skin over the hole after the first submergence, and that bungs it up.

Andy M

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Re: Nixie
« Reply #35 on: January 26, 2021, 02:51:32 pm »

And flood holes or slots at the base as well
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Subculture

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Re: Nixie
« Reply #36 on: January 26, 2021, 04:54:18 pm »

It can be left open ended at the bottom, so mount it so it's slightly above whatever structure you're attaching it on to.

Bear in mind if the fin is very large you can expect it to cause significant roll on turns.

red181

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Re: Nixie
« Reply #37 on: February 03, 2021, 06:51:17 pm »

speed controller arrived today, looking at it (and the 10 price tag!) I think the claim of "waterproof" and 320a are a big exaggeration!  %% %% , and the 60a sticker on the case! {-)
those Chinese factories that churn out these cheap products certainly have a sense of humour.


On a similar subject, I'm surprised at how much "decent" makes, such as Mtroniks actually cost, given that brushed technology certainly is the outdated technology, I would have much preferred one of those, but the price is well out of balance compared with brushless, and the fact that the maiden sail might end up at the bottom of a lake I didn't fancy that financial loss
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red181

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Re: Nixie
« Reply #38 on: February 13, 2021, 08:31:03 pm »

plodding on!


I've not done this in a while!
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red181

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Re: Nixie
« Reply #39 on: February 13, 2021, 08:35:27 pm »

because I did a man read of the instructions right at the beginning, I had the water tight box upside down, meaning the internal frame was too big. I ignored this, but had forgotten how much bigger then 40 meg receiver is compared to 2.4 receivers I have been using for the last several years, and the esc is the size of a house brick compared to brushless esc, that's before we start on how much bigger a nimh pack is compared to a same voltage lipo, so I had to remove a lot of internal wood to make things dry fit :embarrassed:
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red181

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Re: Nixie
« Reply #40 on: February 20, 2021, 09:33:12 pm »

Plenty of paint to help stop rotting wood!
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red181

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Re: Nixie
« Reply #41 on: February 20, 2021, 09:37:02 pm »

running gear in, dry run all works, but nowhere near enough elevator (or whatever its called on a submarine!) deflection, need to rethink that as I'm all the way on the horn holes. Also I was hoping to just attach the servos with double sided tape to the hull sides, but they are moving, cant glue them in as they will invariably fail at some time, and I don't want a complicated mount, this was supposed to be an easy quick build {:-{
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red181

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Re: Nixie
« Reply #42 on: February 20, 2021, 09:45:42 pm »

The receiver aerial, I've read the build log that was in the mag 3 years ago over and over, but I'm not sure what to do. I was thinking it would be a plastic hollow tube, with the aerial wire inside it, and out the top with epoxy at the base to stop water getting in. The build says use a plastic coated wire? not sure what this is, and how the aerial wire is attached, I'm very reluctant to cut the wire on the receiver, and suggestions? can the receiver wire just stay inside the water tight box?


So far pretty much nil from the submariner fraternity, so hopefully someone is looking in to help out please!


Next question is the Perspex top to the water tight box, I have some neoprene foam strip, seems a shame to use screws, as the holes themselves will create more opportunity for water leaks, I found some waterproof tape at prestwich models, will this work better, the battery is inside the box, so every time I recharge its a load of screws to take off, and if the neoprene foam fails then its just a thin bead of grease keeping the water out, any suggestions on this please?
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Ralph

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Re: Nixie
« Reply #43 on: February 20, 2021, 10:43:24 pm »

If you keep the aerial bunched up inside the hull this will reduce range.  I have a shark where I've done that, it's fine for up to about 20-25 feet on 27mhz but beyond that I lose signal (I've just changed this to a 40mhz set but haven't been able to test it yet).  What I did on a couple of other models was is one case run the receiver aerial up inside some plastic tubing sticking up above the model, a bit of grease or silicon on the tube to keep water out.  On the other model I used a bit of piano wire as a whip aerial, cut the reciever aerial short so the total length was about the same and soldered the 2 together where the piano wire came inside the hull.


For charging, could you fit a small hatch into the perspex top (maybe 4 bolts to hold it) so you can reach the battery connector without taking the whole top off?


Good luck with the rest of the build,  been enjoying this thread.


Ralph
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red181

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Re: Nixie
« Reply #44 on: February 22, 2021, 09:05:11 am »

Hi Ralph
thanks for the ideas. I've been thinking about the hatch idea, and decided that removing a load of screws from the Perspex plate on the dry box will be a real pain, and then on replacement will need to be re greased to stop water ingress, I'm club fingers so this will get messy, so thinking about the hatch idea, I've made up a charging lead from the battery with a simple two pin connector which will be inside the watertight box. From the top of the box I have two leads that will be permanently hot glued going into the box, so effectively I have a permanent charge lead outside the box. If I do need to remove the Perspex plate, I can simply disconnect from inside. I'm going to use bullet connectors, as these will be easy to make some sort of cap to stop them getting too wet and getting corroded.


Not yet decided on the aerial, I still cant understand what Glynn Guest meant on his description of the aerial fitting in the model boats mag build description, I think the hollow plastic tube is the easiest way, and you then are not cutting the aerial, but there must have been a reason for the way he did it. I've tried to stick to the original plan as much as I can, why deviate as GG has done all the testing etc, and he knows what he is doing :-)) [size=78%] [/size]
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Subculture

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Re: Nixie
« Reply #45 on: February 22, 2021, 09:40:06 am »

I would advise you to test out your hull's watertight integrity with all equipment removed.

red181

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Re: Nixie
« Reply #46 on: February 22, 2021, 09:59:38 am »

ah!


yes good call! :-))
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Re: Nixie
« Reply #47 on: February 22, 2021, 10:50:10 am »

If you're going to charge the batteries in situ, then make sure you have a means of venting the enclosure. Otherwise you have a potential pipe bomb.

Epoxy resin would have been the best choice for sealing the wood. As well as sealing, it also increases the strength. Paint adds no strength, and over time the water tends to permeate through it.

red181

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Re: Nixie
« Reply #48 on: February 23, 2021, 08:07:50 pm »

"most"  :D surfaces did get a coat of ronseal exterior satin varnish, then paint, so too late now to epoxy unfortunately


servos now reinstalled with mounts so fixed better in place, this did mean the servo rods now need to have a bend to mate up nice with the servo horns, deflection on control surfaces is now acceptable.


The frame is now curing that the Perspex plate will go on, not for initial testing, but once its been water /leak tested Ill put a vent hatch on the Perspex plate to allow the fumes out when charging. I want to have as little as possible with potential leaking points at the test stage


I'm still on the fence about the aerial, it would appear that the more solid piano wire or similar actually helps with the diving, so the hollow plastic tube with aerial wire up it might fail. Just got to think of a way of securing it to the Perspex plate, with enough inside to solder the aerial wire to?


With regard to the tower, is that actually functional? I'm thinking does the volume of water that goes inside the tower when submerging actually help, as its eventually going to be a dorsal fin I wasn't going to bother making the tower, just test then if it all works, make the fin


thanks
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Re: Nixie
« Reply #49 on: February 24, 2021, 05:45:59 pm »

It'll be fine inside the hull, that's the way I run them.
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