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Author Topic: cheap and simple RC sub/dorsal fin project  (Read 40559 times)

U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #75 on: August 16, 2014, 07:14:33 AM »

How you getting on with the shark fin, Paul...any updates? I'll be starting an r/c Orca very soon...




Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #76 on: August 16, 2014, 07:58:53 PM »

Hi Rich,

just got back from hols so not allowed into the shed! I intend to work on cog, and secure the leveller tray better, and see what happens then. I think going by previous advice I have concentrated too much on a level hull whilst stationary, and need to get a level hull whilst moving

Tell me more about those pics!

Paul
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #77 on: August 17, 2014, 07:50:10 AM »

Hi Rich,

just got back from hols so not allowed into the shed! I intend to work on cog, and secure the leveller tray better, and see what happens then. I think going by previous advice I have concentrated too much on a level hull whilst stationary, and need to get a level hull whilst moving

Tell me more about those pics!

Paul


Morning Paul,


The killer whales/sharks/assorted wildlife/ in the picture are the work of a Belgian modeller who is a regular on Andy's (Subculture) Facebook page, they are superb creations, and perform exactly like the real creature once in the water.

I want to base mine on the big fella, using styrene sheet for the fins and make them bigger and more realistic, as in the photos. The other Andy, the one who was going to make the shark kit, is so busy at the moment, what with earning a living and building bits and bobs for people, that the kit will be delayed, so I thought I'd have a go at modifying an MMB SubSonic hull/deck and see what I can come up with.
I have a few ideas in mind of what I want to do, so as they say in all the best places....''watch this space''   ;)


You do need a level attitude on your shark, otherwise you'll confuse the leveller and it will be trying to keep the boat level, but it won't know which way up level is! Does that make sense....?




Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #78 on: August 17, 2014, 04:34:55 PM »

Oh god! Not sure really.  I need to get on with this but my pcf refub is getting in the way. Naybe ill take it to haydock show and let sone sub experts see it in action!
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #79 on: August 17, 2014, 06:53:52 PM »

the tail fin over the prop is a nice idea on the shark, I think I will have to do a sneaky copy of that idea!
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #80 on: August 18, 2014, 11:20:26 PM »

more tinkering, with all bits of ballast removed, cog was a mile out, at 55%, so its taken quite a bit of weight to get it to settle at 40%, water tests might show its now too heavy at the front. No mention is made of this with build instructions, if I was building again, I would be mindful of this and keep weight down at rear, and have wtc further forward. I see a problem as its going to be dragging some serious weight on the nose when I want to surface (see pic, its solid Bronze!!)

The leveller is proving to be something that I just cannot understand. After reading the instructions over and over and over, the more I look at them the more confused I get {:-{, and that's also after emails and a lengthy conversation with Mike at Micrgyros!  :embarrassed:
I currently have the two way pin header fitted on the leveller, but reading over Mikes emails, this should not be installed? so last test was with cog way off, header pin installed, and it still had a degree of success. If I take the header pin out, what does this actually do?

Still debating to operate the leveller by a torch, meaning cutting a clear panel out of the wtc. THe tray is a rtelatively tight fit in the wtc, so no worries about it slopping around.

This has been a real pain of a project!! >:-o
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #81 on: August 19, 2014, 12:43:00 AM »

My bits arrived today, Paul...a nice hull/deck moulded in an off white colour, so all I'll have to do is to add the black sections when it's time to paint it.


As for your leveller problem, I don't know the answer to that...every one of Mike's levellers I've had, I've never touched them. I just installed them wherever they would fit, plugged them in, and away we go...maybe I've just been lucky with mine. I find that as long as you have the boat perfectly level in it's stand, and the stand perfectly level, it's just a case of setting the planes dead level, turning the leveller on, and let it do it's own thing. As I say, maybe I've just been lucky...


Rich
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microgyros

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Re: cheap and simple RC sub/dorsal fin project
« Reply #82 on: August 19, 2014, 01:18:14 AM »

...I currently have the two way pin header fitted on the leveller, but reading over Mikes emails, this should not be installed? so last test was with cog way off, header pin installed, and it still had a degree of success. If I take the header pin out, what does this actually do?

Still debating to operate the leveller by a torch, meaning cutting a clear panel out of the wtc. THe tray is a rtelatively tight fit in the wtc, so no worries about it slopping around.

This has been a real pain of a project!! >:-o
There is a dip switch fitted, if I leave that on, the the lights are lit up, but nothing is happening to control the servo, so what is the point of the dip switch then? If removed, the unit works if I simulate a dive or surface, but it takes over from the tx...... I'm confused now!
ME by email about 10 minutes later date=18 July
Quote
You'll confuse folks. There is a two-way pin header  rather than dip switch. Google dip switch and you get pictures of a miniature switch.
Leave these two pins open. If you insert a shorting jumper it nulls the sensor input....
Can you telephone me on 0141 416 2001 or xxxxx..........if you have any difficulty with regard to the operation of the AST2?

And do the side to side roll test I suggested.
The pitch control, from the picture, doesn't look to be aligned true. If it is offset then sideways roll will have an unwanted influence.

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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #83 on: August 19, 2014, 07:24:44 AM »

just for clarity here, its the whole job that has been a pain, not the leveller, and not the model either, its just my misunderstanding of basic submarine principals. What I thought was going to be an easy, cheap, fun project, has proved otherwise , and only really caused by me, not the leveller, not the model . It is a challenge, and something I want to see out to the end, but unfortunately the spend is increasing all the time!

I appreciate your input Mike,  (very much appreciated by the way) it does not help with my understanding. I cannot understand the point of the jumper. If its in place, and nulls the sensor input, what is the purpose? Also, I cannot understand the sideways roll issue and what that means to the sensor.

It will be interesting to put it back in the water with that large weight, I had better use a shallow lake! :}
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #84 on: August 20, 2014, 11:46:05 PM »

unfortunately I have to think about the future of this project, following yet another morning messing around.

Mike afforded me a long conversation (again  :embarrassed:) about the leveller, and I now have a better understanding of what it does, and how it does it.

Its the model I am struggling  with, as thought, the weight to get the cog something like correct is miles out, and much too heavy. My only answer is to move the wtc much further forward, this will mean the weight of the battery comes into play to help with cog, but fundamentally its very tail heavy, so even with ballast as it was two weeks or so ago, its always going to be struggling as its too tail heavy.

Moving the wtc can be done, but its going to mean changing all the pushrods, and remanufacturing the propshaft and mount, which is well and truly epoxied in. This might now call in extra shaft supports etc etc and I have very limited patience left with this "cheap and SIMPLE" project :((

Im going to have a think about it, and some long conversations with sub experts at Haydock (warning to any going!). I would very much like to beat this anf get it working, but the time invested so far, and the money, is proving to be excessive.

Anybody fancy a commission build? !!!  ;)
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Subculture

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Re: cheap and simple RC sub/dorsal fin project
« Reply #85 on: August 21, 2014, 09:59:10 AM »

Fundamentally, the WTC should be positioned so that the centre of the cylinder lines up with the intended C.G. You do have a bit of wiggle room, but generally location in a teardrop shaped hull is dictated by the limited space available.

You should be able to balance the boat using a piece of string made up as a sling. Hold the boat near the ground or above something soft (e.g. water) and see if it balances at the right point. if not adjust the weight until it does, but don't mess with the WTC position, as that will just make things worse (because you then adjust the centre of buoyancy).

If the boat balances at the right point, put it in the test tank. If the boat sits level you're good to go, if not then add some foam polystyrene just below the waterline at the end that is sitting low until it becomes level.

U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #86 on: August 21, 2014, 10:22:10 AM »

Good advice from Andy there, Paul...you don't need to be mucking about altering cylinders and push rod lengths, etc...centre of cylinder = centre of gravity of the boat. Always a good start point, and as Andy said, you do have a bit of 'wiggle room' (technical terminology...)


Ideally, aim to get the waterline just level with the bottom of that little hump on the deck (I'm using that as the base of the dorsal fin on mine) that should allow you to submerge with just a sniff of power.


But first, get everything level with the creature on the surface...add small pieces of foam or lead as needed, but it does need to be level before you go any further.


Rich
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #87 on: August 21, 2014, 10:53:23 AM »

Here's how the fin looks on mine, Paul...


Rich
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #88 on: August 21, 2014, 12:29:18 PM »

Another pic of the hull with the fin fitted...2mm styrene, with the edges sanded similar to an aircraft wing profile. Making the tail at the moment..on the third attempt so far.  >>:-(



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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #89 on: August 21, 2014, 12:54:20 PM »

Third attempt at the tail fin...


Rich
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Re: cheap and simple RC sub/dorsal fin project
« Reply #90 on: August 21, 2014, 02:18:13 PM »

Hi Paul (Red181),

We look forward to talking with you at Haydock Park - the AMS stand.

Bring the sub along, if you can. There are a couple of small pools, just down the Grandstand from us.  The pools will not be used all the time so we can probably help you with trim etc.

We will all be there both days.

See you David (Forrest)
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #91 on: August 21, 2014, 10:49:26 PM »

Hi Rich

If you get yours to work, and I bet you do, I will tie that lump of bronze around my neck and jump in the lake %%

David, thanks for the kind offer, I will say hello with the disaster shark, I bet in the right hands this can be sorted, I'm not after much, just a dive to the height of the fin, and some sort of control as to where it comes up again would be nice, and a degree of turn, that's all!!, and avoid scraping the bottom of a lake and dragging back up old Ford Cortina's and shopping trollies!   :}

Paul
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #92 on: August 22, 2014, 07:08:26 AM »

I'll get it to work, Paul...one way or another I'll get it to work. The problem at the moment is getting the two halves to fit together. I've big enough gaps around the thing to be able to drive a bus through them...   >>:-(


I'll have one more go today at it, then I think I may do away with the hull bottom and just clip the wtc into the deck section, once in the water nobody will see it doesn't have a bottom to it.


Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #93 on: August 22, 2014, 03:28:57 PM »

Inly prob rich the bottom has all the shaft mounts and planes etc
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #94 on: August 22, 2014, 08:10:26 PM »

No problem, Paul...two Terry clips will secure the cylinder in the deck, and attach everything else to the cylinder. Just playing with that at the moment...we'll see what happens.


Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #95 on: August 25, 2014, 12:05:56 AM »

It was a fruitful day at Haydock on Saturday, many thanks to Dave and co on the AMS stand who looked at my Dorsal fin sub. They identified a few problems.

First the fins are all wrong. I had made them from solid depron, covered in glass cloth. It was pointed out, when the sub dives, they then start to act as ballast, which then messes up the whole thing. Whilst things are not working correctly, I was advised to disconnedt the leveller, until things get sorted to a fashion, then reconnect. The "o" rings on the end caps need replacing, they where not tight enough, and when things are sorted seal up the motor end cap.

We discussed ballast and cog at length, and the guys said get a level attitude on the water, using blue foam to ballast, I was using a foam that was holding some water.

After all that, They where confident it should work! :-))

So this morning it was back to the lake at 8.30am.Perfect day, sunny, warm, no wind, and no audience :D Fins removed, all ballast removed, I started to balance the boat. After 3 hours, gave up :(( When level on the water, its a real struggle to maintain surface running. If I induce a dive, even with very gentle change in plane attitude, its an immediate crash dive, so I then have to throttle off and wait for it to surface. Even with a vastly increased surface area, and maximum movement, the rudder still has little effect, so I am bored of it now and need a break from it as I have other jobs to do, so its now in the attic.

I am sure this will work, but I'm too fed up with it now.

Ill say it again, anybody fancy taking this on as a commission build, Ill do it! ok2

For now, its a shelved project
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Re: cheap and simple RC sub/dorsal fin project
« Reply #96 on: August 25, 2014, 11:03:11 AM »

Whether the fins are made from foam or weapons grade plutonium the upthrust created when submerged will be the same. Archimedes principle.  :-))

The fitting of the o-rings is a common complaint on this model. Reason for the problem? The caps are too small for the pipe. You can pack out the endcaps with tape- a bit bodgy but it works, or you could also try some 1/8" thick o-rings which give you a bit more compression than the standard 3mm ones.

The twitchiness sounds like either too high c.g or too far aft or both.

Better steering requires bigger rudder, preferably in the prop wash.

U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #97 on: August 25, 2014, 12:26:44 PM »

Paul, you'd be much better off attempting to trim and ballast the boat (creature?) indoors, in the bath. If I were you, I'd start afresh with it...remove all the foam and ballast, and completely restart the operation. It seems to me that you've reached the point of totally confusing yourself (been there, done that) with bits of foam and lumps of lead in all the wrong places.


Start off by getting the cylinder position and the c of g sorted, with the boat level...then start adding lead and foam until you reach your desired water line, again making sure that the boat is level in all aspects. Once there, give it a push to submerge it and note what attitude it goes under at, and what attitude it surfaces at. Add/remove lead/foam and keep at it...it can be a long drawn out process, hence the suggestion to do it indoors. it'll drive you mad, you'll swear and cuss a lot, but all of a sudden you'll realise you're there with it.


Andy is right re. the end caps...mine don't fit any sense either. I packed mine out with electrical tape...about one and a bit turns if I remember rightly, and I also put a wrap of tape around the outside...belt and braces.


Don't abandon it, leave it for a couple of days or so, then come back to it and start over. You'll get there, trust me...


Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #98 on: August 25, 2014, 01:28:02 PM »

Thanks for comments chaps
my o rings where quite tight to start with. Its been pulled apart so many times I think they are worn now. The bath os a small corner one unfortunately.
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Re: cheap and simple RC sub/dorsal fin project
« Reply #99 on: August 25, 2014, 02:15:37 PM »

Very unlikely you've worn the o-rings. The finish inside of PVC waste pipe is usually quite poor as the fittings are designed to seal to the outside, which has a very good tolerance. I inherited one of the MMB Sub sonic wtc's as part of a job lot of bits, and the fit of the end caps was found wanting. I machined up a replacement pair of PVC caps as a demonstration, but I know not everyone has access to a lathe. Had I been in the position of having to use the supplied caps, I would have gone for some thicker seals.

You must have a very small bath if you can't get a two foot long boat in!
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