RC India

Hello Everyone!

I am a brand new member to this forum. I have been a modelller of sorts for the last 35 years. My areas of interest have been basic aeromodelling, basic RC (read cheap Chinese and not so cheap Japanese toys), ship and boat modelling. I am heavily into scale plastic models, model rocketry and also into model railways (HO Guage). I am originally from Kolkata though I now reside at Guwahati, Assam.

I have taken on the challenge of my life. I am trying to scratch build a 1:125 scale dynamic diving, Akula Class Submarine. The electrics are on a shoe string budget for this particular model. I need 4 chennels and I plan to cannibalise them from Chinese RC Cars. (2 dismantled cars should get me a semi decent 4 channel within Rs.1000/-).

Does anybody have any experience of building anything like this? I would request you to help me with any information that you feel is relevant. Just remember that you are talking to an Idiot, keep it simple. From time to time, I will pester you guys with queries that may seem ridiculously simple to you - please remember, they are of vital importance for me. So please have patience with me.

The basic shape of the sub is made out of pinewood and a lenght of 3" dia PVC water pipe. She will have an overall length of 35".

Gentlemen (and Ladies), I need some suggestions for cheap Servos (Unless you decide to eliminate them altogether!!!), ESC and batteries. I am planning 12V electrics, though I am open to 6V if you think it would be better.

I need to control the following:

A. Forward Dive planes
B. Stern (Rear) Dive Planes
C. Rudder (Top and Botom)
D. Motor speed and Forward / reverse

Since she is a Dry Hull Dynamic Diver, there is no requirement for Ballast tanks as of now. I will think of that if I decide to convert her later to a Wet Hull Static Diver.

Any suggestions/ guides are more than welcome.

Thanks and Regards,

VC

If you use the car motor and power system itself, this should work out without too much pain (assuming it also supports your "reversing" requirement).  You will have to build some kind of DIY setup that brings the 2ch + 2ch transmitters into a single 4channel transmitter.

There are already multiple threads here on making cheap chinese 2ch cars into airplanes, and the associated difficulties. But boats are somewhat simpler to deal with using this setup. 

BTW, I hope you realize that you will have to ensure that all the power system is totally waterproofed. 

If you go for your own ESC, I feel that will complicate things significantly, in terms of compatibility with the Chinese car receiver.

Thanks Mod!

I have figured out a way to combine 2Ch + 2CH into one unit. That is not a problem. Waterproofing has also been taken care of as she is designed to be a Dry Hull Dynamic Diver. Reversing the sub will be easy, though how accurate the reverse movement will be, I am not really sure.

You are right, the ESC may not be compatible with this cheap set up. I may dispense with it altogether. I had built a torpedo boat with a 2 Ch Chinese set up. One Channel for speed and the other for the rudder. It worked just fine.

Since the Akula is a test ( a rather BIG one!) I am willing to experiment. You are not going to believe the kind of research I have done for this Baby. Wish me luck, and pray that she works.

Thanks again for your inputs.

Cheers!

The above mail should read as Thanks Administrator, instead of Thank Mod. My apologies for the oversight.

can u share the procedure u have used
please tell us this detailed with pics if possible

especially if u can tell how to make 2 2ch transmitters into 1

if u know,VC,then please tell us the way to combine two 2ch  tx into one
well whats the current progress report

Hi Ankur.

I tried and accumulated some junked cars to begin the process. However, two members of this forum were kind enough to let me have the Tx and Rx units. One of them actually gave me his Futaba Tx for FREE. Thus the DIY conversion project with Car RC units has now been mothballed. :giggle:

However, I don't see any real problem in doing it. All you need are 2 units that don't interfere and merge them together. You need to create a wooden box to house the 2 Tx units side by side. May look a little bulky/clumsy, but it will work. The 2 Rx units can then be used in tandem inside the model. They don't need to be interconnected other than drawing the same power supply and joined to the same Rx antenna.

The Rx will not be able to power servos but can power small motors or Stepper motors to control direction or any other action. Typically Speed (forward/reverse), Direction, Lights and one more :headscratch:???

Remember, NEVER EVER think of using these on aircraft of any sort. Practcable as this system may be, it is certainly not practical. However, with road vehicles and boats it should be useful.

Hope this helps.

Cheers!

VC

well can two sticks be used to control 4 channels
can u make such a system

I spoke to the person in Chennai who has two working submarines .
He is an NCC ship Modeling instructor  and  does not use them much  as you have to be prepared for high maintenance .
His words of advice were :

1) The car type radio's you are talking about might have range related issues  under water  as they are not  professional good radio's meant for range .
2) What ever the sealing you may do   stopping water  intake into the radio  and battery compartment is physically not possible  as it enters thru the small holes  for servo  control push rods  etc. So be ready to spend for receivers/ batteries   as chances of receiver and battery   failures  is very very high.

The Pressure of water at  5 ft depth as per is around 1 KG hence the water ingress into the dry chamber is under pressure , for a person like him who makes ship models as a part of his job   the water intake is around 1 glass in 10 mins of sailing .

Sai

Dear RCFORALL,

Thank you for your inputs.

There are some basic types of Submarine models.

A. Dry Hull : A sub where the hull interior stays relatively dry as there is very little chance of water entering. The only apertures being for the prop shaft, Stabiliser and rudder linkages.

B. Wet Hull : A sub where large apertures allow the interior of the hull to be flooded and this is controlled by a 2 way pump (or other means) that will draw and eject water to control buoyancy.

C. Positive Buoyancy Subs: This sub will have positive buoyancy and remain afloat, which means the craft will automatically surface once power is cut out. Sits on the water with the water level at the deck level.

D. Negative Buoyancy Subs: A craft that sits in the water with water atleast upto the conning tower/above the sail. Needs a ballast pump to pump out the water from the hull to rise above the surface.

E. Dynamic Divers: Subs that have Positive Buoyancy and dive under the surface using high speed and front/rear diveplanes at an inverted angle of attack. Once the depth is reached, it is used in cruise mode and once power is reduced, it travels back to the surface.

F. Static Divers: The REAL thing! A sub that can dive while in static mode. Takes in water into the hull, dispels air and dives. Pump switched on, water is pumped out, bouyancy increases, sub surfaces. This is the most complex of all models.

All the above need Water Tight Chambers or WTC's which house all the electronics. 5 feet of depth is good, however, for a novice, scratch built sub (like my Akula), I will be happy with an operating depth of 2 feet. Simple rule, if you can't see it, you can't control it! You and your friend are right, WATER WILL ENTER, we can only minimise the ingress.

Radio ranges will diminish in water with high chlorine (swimming pools) and chemical content and reduce drastically in sea water. If you read my earlier post, I have long abandoned the idea of using Toy RC units. I have got myself a couple of 4 Ch sets, they should be sufficient.

Model subs ARE an expensive proposition, just the hull sells for around Rs.30,000/- and complete sets can cost between 50K to 1.5 Lakhs. Even the most experienced sub modellers like David Merriman advises us to follow a simple rule - Dive, Dismantle, Dry, Store - the sub HAS to be thoroughly dried before storage.

I was fully aware of this water seepage problem even before I started planning construction. My initial practical tests show that I am overcoming the issue. CAN BE DONE!

Thank you once again, for your inputs.

I would be grateful if you could revert with 2 pieces of information :

(a) The subs that your friend has, are they scratch built or bought models? What are the specs of these babies?

(b) Could your friend please advise me where to get Ship model kits in India. Since he is a modeller for the NCC, he will definitely know. I have already posted this query on the forum yesterday. I desperately need phone numbers / addresses.

Regards,

VC

I want to see this...

Wow an RC submarine !!  How delightful :o

But unless one is a sheikh with a private pool where does one drive it  :headscratch:

in the sea perhaps? while going in a real boat. with FPV ?

Have you guys observed the date of this post? It was my first contribution on this forum.

:P

yes i have... ;)

Vc riding the nostalgia wave  ;D btw I saw the date too ..Also you are no longer  " brand new" in the forum so one could guess ... 8-)

Two submarines lying mothballed. One will be built soon, hopefully.

May we see some pictures please? ;D