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Author Topic: cheap and simple RC sub/dorsal fin project  (Read 40523 times)

red181

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cheap and simple RC sub/dorsal fin project
« on: June 10, 2014, 09:42:08 PM »

After asking for a tx and rx in the wanted section, it seems I need a lot of help, so I have started this thread :embarrassed:

Ok, I have a nice model of the Jaws boat "Orca". It has sound unit, smoke  unit, nav and cabin lights, and so on. I've had it for a number of years, and only really sail it once or twice a year, as its not really my sort of boat, but I do like it and wanted to do more with it. I fly helis, fixed wing, and do boats, submarines are an rc discipline I don't know, so thought it would be a good fun project, something different, but its proving to be more of  a problem than I expected, but now I have started, I would like to see it through, its now I know I need help! so here goes :-))

I looked for some time 12 months ago for a cheap way of converting a rc sub into a dorsal fin. I wanted it to submerge the height of the fin, go forwards and turn, and be able to sail at a slightly below waterline so the fin and top of hull was evident. After trying numerous toys, and searching endlessly for something pre built but cheap, I was lucky enough to have donated by Rich (U33) the two halves of the MMB Subsonic. August 2013 I picked up from MMB the parts kit, and last month finally started the project, with absolutely no Submarine experience.
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #1 on: June 10, 2014, 09:51:23 PM »

so, the build was quite easy, using the dvd provided, pictures tell a story and this made it quite easy. Everything went together quickly, the delays caused by having to wait for  epoxy to cure. I wanted this to be cheap, as it was something of an experiment, if it all works, I can then convert to better components.
First problem, all the brushed motors where thrown away ages ago as I use brushless in all my rc models, I neede a esc, and I have lost count of all the 27 and 40meg gear that I got rid of, all my stuff is 2.4!
I managed to scrounge a motor and esc, but had to buy second hand tx and rx.Futaba FP-T6NL tx and Futaba FP-R103F rx with crystals bought as a pair, I thought this would be fine
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #2 on: June 10, 2014, 10:01:13 PM »

First of all, I realised after the purchase the tx is mode 1 throttle on right, not a biggie, I can get over this. So all installed in the wtc and a water test in the bath, no leaks! Battery in and a bath test for ballast, now it leaks :((
After a lot of trial bath tests, it would seem there is a real small drip but I cant locate the source, although its motor end. I tried a film of bathroom sealant, thinking the motor end cap once on will never haver to come off, this seems to have worked. I have noticed the battery removal and refit, although appears to be in the same place, seems to alter the ballast every time, some times the hull leans over, which is a real pain, but I am sure practise will make perfect.
I tried to set the rear planes level, but the adjustment of the servo links is so difficult as half of it is inside the sealed wtc, and I keep having to take it apart to adjust. I fitted the servo rod links provided on the furthest out horn holes to be adjusted later. The tx has subtrim and endpoint adjustments so this should come in handy later
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #3 on: June 10, 2014, 10:09:12 PM »

Did I range test prior to final fit........................NO >>:-(

Off to the local lake feeling confident, but a few feet away I get all strange cliches, and a wide open throttle, and then nothing, and I am standing downwind, so have to wait ages for it to float in, luckily, it does float! Should have done the range test {:-{

An hour of fiddling, and its back home. Now I am thinking should the aerial wire be outside the WTC, so I do that through a small hole, sealed with cyno. Back to the lake, its still the same, no range. I am able this time to try things close to the bank, and its not great :(( slow speed (very slow!) it seems to sail reasonably level, and at the right depth, anything above 1/3 throttle and it dives at 45 degrees, and the angle of the planes does not seem to have any effect, holing full up elevator it still wants to dive. I tried some extra ballast in the nose, but now the tail is heavy.

After a lot of messing around, in a sudden spark of imagination, I decided to fit the rx, esc and use the tx in a rc boat to see what range I have above the water line, and to my horror, its only two meters, so after all that I have a rx/tx problem <:(
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #4 on: June 10, 2014, 10:15:25 PM »

After posting on the wanted section this week asking for another 40 or 27meg tx and or rx, I have been advised that corona rx are compatible. I suspect the rx is faulty as the aerial has been meddled with, something I didn't see at first, and its pretty obvious, the colour of the wire changes! :embarrassed:

I now have to wait to get  this problem sorted, just about to order a synthesised corona 40meg rx which hopefully will work with the tx. This time I will range test in the boat first. Whilst I wait, any help advise would be appreciated, particularly with the diving problem, and ballast.

Here you can see the idea, I have not yet worked out how I am going to control the shark and Orca, maybe someone in the Wirral area would like to help! By the way, for any New Brighton members, that is where I tested, I did a great job of scraping the weed up from the lake bed!

Thanks

Paul
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #5 on: June 10, 2014, 10:22:11 PM »

I have had to use some "modellers license" with the scale of the shark, its obviously too long, but it does not really matter, its the fins that matter, these too have had to be overscale compared to the boat, otherwise you cannot see it on a relatively small lake.

Its quite unnerving having something that disappears under the water, how do you sub boys cope when its a lot of money going out of sight! :o
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spooksgone

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Re: cheap and simple RC sub/dorsal fin project
« Reply #6 on: June 11, 2014, 08:15:40 AM »

I remember Ron Perrot once said in either, mmi or model boats magazine, the second best feeling known to man is seeing your new model submarine surface!
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Subculture

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Re: cheap and simple RC sub/dorsal fin project
« Reply #7 on: June 11, 2014, 09:39:24 AM »

What sort (if any) of control surfaces are you using to control the attitude of the boat?

Regarding the leaking, I would carefully check the fit of the endcaps to the tubing. I received an MMB sub sonic tube, and the end caps had visible air gaps between the cylinder wall and the o-ring.

There are three ways around this, machine some new endcaps; best but difficult without a lathe. Fit a thicker o-ring, the standard items are 3mm thick, you could try some 1/8" thick o-rings (3.17mm). Or add some bulk to the groove by removing the o-ring and running some thin cyano around the bottom of the groove or packing out with PTFE plumbers tape.

red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #8 on: June 12, 2014, 10:54:06 PM »

Hi Subculture, I think the o ring is now sealed using a thin film of bathroom sealant. With regard to control surfaces, do you mean the two rear planes? if so, that is all, the front planes are static, and have not been fitted as yet, didn't see the point in them, unless you can tell me otherwise. I thought the reap planes, acting like elevators on a plane would have the desired effect, It must just need trimming, any advise appreciated
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Subculture

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Re: cheap and simple RC sub/dorsal fin project
« Reply #9 on: June 13, 2014, 09:45:20 AM »

Silicone caulking is a bit fragile, don't be too surprised if the the leaks reappear at some point.

It sounds like you're using the standard subsonic dive planes- I thought perhaps you might be using something more shark like. The issue may be that you are porpoising near the surface, which is common problem for model subs when they operate at anything past a snails pace. A leveller should sort out these issues. Make sure your rear plane linkages are slop free.

You may also want to consider actuating the front planes in addition to the rear and having the rear planes controlled automatically by the leveller. This should make the shark rise and dive in a very controlled way.

U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #10 on: June 13, 2014, 03:26:18 PM »

Just a thought, Red...you might be interested to learn that my buddy Andy (username 'tattooed' on here) is about to start making a prototype for shark kit. It's going to be one or two steps up from basic, it will be capable of submerging/surfacing at your command, but it won't be loaded with electronic aids. I don't know how far he's got with it, he's been a busy boy at work recently, but knowing Andy as I do, it will be good when it's done. It may well be worth your while sending him a pm (tell him I sent you) and having a chat to him.


It's not going to be a vast manufacturing job (Andy works out of his spare bedroom) but it's just something he's wanted to do for a while now...we've had several long chats on the phone about it over the last few months.


Rich
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Rich

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unbuiltnautilus

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Re: cheap and simple RC sub/dorsal fin project
« Reply #11 on: June 13, 2014, 05:32:45 PM »

Sounds fishy :}
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #12 on: June 13, 2014, 05:54:13 PM »

"groans loudly..."


Rich
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #13 on: June 13, 2014, 06:01:26 PM »

Post office say I have a parcel to be collected, so tomoz should have the rx so its back to the lake. I was wondering how much travel (deflection) I should be looking for with the rear planes? What attitude as a starting point should they be at, I was thinking level, but not sure now.

I was thinking of doing it in bite size chunks, lets get it sailing above the water and go from there. I here you subsonic, but I am really trying to avoid over complicating things (believe me, making the front planes move is overcomplicating!) so should I fit the front planes as static none moving, will they help or hinder?

 Have you got a link to a leveller and will it achieve anything in this very basic project

 I will be interested in the developments of Andys project Rich, sorry for all the questions, don't get much time off work so need to be well prepared when next visiting lake! :-))
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red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #14 on: June 19, 2014, 08:01:40 AM »

I have now matched the receiver to tx, a bit fiddly, but its now done, 8 ch synthesised for 15, its unlocked another couple of channels on the tx, so that is a bonus! Everything is now reinstalled in the subsonic, batts charged, no I didn't do a range test in the boat first, too impatient!  :embarrassed:

No slop in linkages, and a small amount of up attitude on rear planes, I hope this will help in surface running, that is todays task as I am off work.

Now, should I fit the static front planes, do they do anything? and the aerial wire, its very long, should this come out of the wtc via a sealed pin hole, or stay inside the wtc? If so, I assume you cant coil it so does it just float around inside?

Thanks
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #15 on: June 19, 2014, 08:43:10 AM »

Aerial wire is a pain in the proverbial...I confess in all but one of my subs I've just scrunched it up and stuffed it anywhere out of the way. The X craft did get a 'comb' I made to wrap the wire around, but it broke in the end... The choice is yours really what you do with it.


Front planes...if you make them operational from the tx, they will control your depth, then fit a leveller to the rear planes and that will keep the boat level at whatever depth to choose to sail at.


Rich


(PS...did you contact Andy?)
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Subculture

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Re: cheap and simple RC sub/dorsal fin project
« Reply #16 on: June 19, 2014, 02:10:06 PM »

Try it inside the tube, if you experience range issues, then run it through a gland into the wet. Make sure you put a dab of araldite on the end of the aerial wire to stop water working its way up the insulation.

For a leveller try microgyros.com

red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #17 on: June 19, 2014, 05:15:19 PM »

Yeah Andy and I spoke Rich, thanks :-)) he is looking in from a distance, the problem is, I am best part of 100 in with the subsonic, 30 tx, now 20 corona rx, and a few other bits and bobs, and today was a disaster! <:(

Range issue, still only 6 feet or so, so looks like the tx is a problem. A tried some surface running close to bank, anything over a snail pace and it wants to dive, even with a degree of up elevator on the rear planes, so couldn't even manage a surface run. I tried fitting the static front planes, it helped, and looked better, made it more stable. I have a long way to go here, as pulling the wtc out at lake side isnt ideal. I have nowhere near enough travel on either planes, or rudder. Don't have any more room in wtc to extend servo horns, so will have to cobble something up on the planes to give more travel. I was thinking of making the rudder and planes bigger, and fabricating  a linkage from front to rear planers so all 4 work, thinking this might help with surface running.

Its going to be too big a job operating front planes from the servos in the wtc, I would have to buy a new endcap, rods, tubes and seals, then the linkages would run past the battery, which itself will cause problems on battery removal for charging.

I removed all electrics from sub, fitted to a boat, like I should have done in the first place, back to lake, and its got very poor range, so must be the tx. Tried fresh batts in tx, and tried different channels with throttle in case the tx pots where bad, still the same, looks like its another purchase, another tx >:-o. This cheap "fun" project is now becoming a chore!
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #18 on: June 19, 2014, 06:23:41 PM »

Oh my gawd, Paul...it doesn't sound good. I won't tell you that I binned a couple of old 27mhz radios a couple of weeks back.... :embarrassed:


I reckon you'd be better off sorting out the radio problems first before worrying about the way the boat behaves, at least you'll have one problem out of the way. Perhaps you should settle for a shark that just follows your Orca at perisc...sorry, dorsal fin depth. One thought does occur to me...if you were to fit a cheap 2.4ghz radio, the shark would only dive to a depth of a few inches before the radio loses signal, and pops up again. If you watch a shark in the water, they do behave like that a lot of the time. Ebay has loads of cheapie 2.4 radios for less than 20...might be worth a thought?


Rich
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Re: cheap and simple RC sub/dorsal fin project
« Reply #19 on: June 19, 2014, 06:26:55 PM »

Don't think that will work. You need to persevere with 40mhz.

U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #20 on: June 19, 2014, 06:34:47 PM »

It would make the shark look more realistic though.


Rich
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Re: cheap and simple RC sub/dorsal fin project
« Reply #21 on: June 19, 2014, 09:01:01 PM »

If you think it is the TX, then I would have alook inside the set. I have some familiarity with that set, as my Dad owns the same model, and I converted it to 2.4ghz for him.

It's a fairly straightforward analogue unit, the tuner board blugs into the encoder board, and I would be inclined to check the wire feeding to the aerial, making sure it's intact and well attached to both the board and the aerial. Would also check the connector between tunign board and encoder, and also check that the set isn't suffering from dreaded black wire.

red181

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Re: cheap and simple RC sub/dorsal fin project
« Reply #22 on: June 19, 2014, 11:18:55 PM »

Tx looks ok inside. Nothing amiss. I have a  couple of cheap 2.4 sets so could give one  try. I only want to go to height of fin in depth but expect that too be deep enough to loose signal.  I might have
a levelled on the way from another mayhemer so if it is how am I going to transfer control rods from back to front im not sure how a leveller works?  Is it mechanically attached to the rear planes? Can I just run linkages from rear to front?
Thanks
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essex2visuvesi

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Re: cheap and simple RC sub/dorsal fin project
« Reply #23 on: June 20, 2014, 06:59:58 AM »

The leveller sits between the servo and the receiver.  I'll have a look in the shed, might have a 40 txt you can have as well
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U-33

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Re: cheap and simple RC sub/dorsal fin project
« Reply #24 on: June 20, 2014, 08:19:03 AM »

I have an idea that this ''cheap and simple RC sub/dorsal fin project'' has exceeded it's title....   :embarrassed:




Rich
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