Static and Dynamic Diving

[Subculture]

They might be at school. It's also a good opportunity to experiment with microcontrollers and foster an understanding of how the radio system works, rather than it appearing like a box of black magic.

I'm personally a bit disappointed with the way radio manufacturers have just bolted on computers to radio sets, without passing on a lot of benefits. We're still stuck with old fashioned analogue methods of transmission and decoding first introduced in the 1960's, albeit with micro processed pulses to help remove glitches (in some cases).

I'd like to see radios that only transmit when something has altered, i.e. a stick moved, switch thrown etc. This would save a lot of battery power in the TX, and this is the way TV remotes operate for instance.

I guess the companies producing the kit consider 'if it ain't broke don't fix it'.

[He Who Shall Not Be Named]

You could rig a model submarine for full function with 2-channel R/C by the use of a couple of micro switches and a bistable relay.

The relay can be flicked either way using the microswitches, set-up so they operate on the extremes of throw of either the dive plane servo or the rudder servo (the former makes most sense).

This would enable you to switch the motor for forwards operation only.

Another alternative, if you're comfortable with doing a bit of coding, would be to program a micro controller to intercept the pulse from the receiver, and switch a function depending on certain conditions e.g. two quick forward flicks of the dive plane stick, switch motor forwards, two flicks back switch motor reverse. Using something like a Picaxe would only cost a couple of pounds, and you could add several auxiliary functions to a basic set.

Thankfully, multi channel sets are quite cheap these days, especially if you look around for S/H bargains, as a lot of people are crossing over to 2.4GHZ sets and letting their old equipment go quite cheaply.

I learned r/c flying/operation with rubber wound escapements, went on to reed systems, then pulsed-rudder and elevator (mechanical de-coding), then 'galloping-ghost' (more mechanical de-coding but with a bit more finis), and finally the first digital (somehow I by-passed the analog) proportional systems. AND never looked back!

Why in the hell would anyone be so cheap as to try and built multi-functions into a limited function system. Save your dimes and buy a proper r/c system!

David,

[Subculture]

You could rig a model submarine for full function with 2-channel R/C by the use of a couple of micro switches and a bistable relay.

The relay can be flicked either way using the microswitches, set-up so they operate on the extremes of throw of either the dive plane servo or the rudder servo (the former makes most sense).

This would enable you to switch the motor for forwards operation only.

Another alternative, if you're comfortable with doing a bit of coding, would be to program a micro controller to intercept the pulse from the receiver, and switch a function depending on certain conditions e.g. two quick forward flicks of the dive plane stick, switch motor forwards, two flicks back switch motor reverse. Using something like a Picaxe would only cost a couple of pounds, and you could add several auxiliary functions to a basic set.

Thankfully, multi channel sets are quite cheap these days, especially if you look around for S/H bargains, as a lot of people are crossing over to 2.4GHZ sets and letting their old equipment go quite cheaply.

[toppack]

Actually rick you can dynamically dive anywhere - you don't necessarily need a big operating area. And in fact a big lake I believe is one of the worst places for a Dynamic Diver.

If you will notice I put a laughing face after that statement which means I was joking about the 'big lake'.
What I was saying is, that more room is needed for dynamic than static dives, of which there can be no doubt.
Many factors will determine how much space is needed, such as model-size, flotation-trim, size of DPs, speed of model, etc.

[Slats]

Yes, The main thing you need is a Big Lake for a Lot of Running-Room. :D
Of course it's not a true submarine but can be a lot of Fun doing dynamic dives.
We actually don't Have to have those High Dollar systems to have fun.
But if you're trying to Impress the other RC guys at the lake or you enjoy the technical challenge of a full blown system, then that's another story. :)

Actually rick you can dynamically dive anywhere - you don't necessarily need a big operating area. And in fact a big lake I believe is one of the worst places for a Dynamic Diver.

Since the topic of a dynamic diver (DD) has been raised lets cut through the common myth of operation and why I believe these boats should only be used in controlled waters like a pool.

First many people believe a DD is a boat that simply always pops back to the surface if you throttle off. Not true. The deeper you go the more the water pressure acts upon the reserve bouyancy and subsequenty you might stay exactly where you are.

There are two big pitfalls I believe and have witnessed first hand in blue water ops like a lake with a DD. These should be obvious but are somewhat not well known to the new guy. I mention the new guy as a lot of people come to, or try out the RC sub hobby by going for a DD first. Nothing wrong with that, but I wish the new guy would take heed of these.

(1) First is you get a boat that is very positive and the thinking here is it is so positively bouyant that it requires so much speed to dive dynamically that any reduction in speed will see it rocket to the surface. The big problem with this is that the boat needs to be driven fairly fast, and here in lies a big problems of driving submerged in a lake at high speed. The boat will get away from you and you will get to points where you loose sight of it. At high speed visual contact is far more crucial than lower speeds where you might be able to predict its track. Throttling off might mean you pop back up, but if you are going deeper as you lose sight of it you might be now too deep. Have seen a Robbe Seawolf lost in this manner. It was recovered by a diver in 20 ft of water and when found was completely dry inside!

(2) Making pt (1) above more likely is going for a simply 2 channel setup. If you can plane up (via an extra channel) in that situation do so.

(3) Next you eliminate the high speed requirement to dive dynamically and stay submerged by making the boat still positive but less positive by ballasting it lower in the water. In doing so you now have made the depth at which the reserve bouyancy can be overcome by pressure shallower. - Have seen the Robbe Seawolf lost in (1) recovered and lost again due to this.

(4) The next problem with DD relates to flooding. Whilst flooding can occurr with boats employing a ballast tank, minor flooding can be overcome with blowing the tank and surfacing. Once with a DD you are at a submerged point where the pressure has equalised / negated or is exceeding your positive displacement, any leak will take you negative and given you have no ballast tank to blow you loose the boat. Have seen this with a Robbe U boat that was lost for 5 weeks and found in just 6 feet of water.

I am not being negative - just realistic. DD are a good way to start and learn the basics but the claim they always just pop back to the surface with loss of forward momentum is false.

[toppack]

Yes, The main thing you need is a Big Lake for a Lot of Running-Room. :D
Of course it's not a true submarine but can be a lot of Fun doing dynamic dives.
We actually don't Have to have those High Dollar systems to have fun.
But if you're trying to Impress the other RC guys at the lake or you enjoy the technical challenge of a full blown system, then that's another story. :)

[redboat219]

Would it be possible to control a dynamic diving boat with just 2 channels. 1 for the throttle and the other for rudder control? The diving planes would just be set-up at a fixed angle. Depth control would be dependent on how fast water moves over the dive planes.

[toppack]

Static and Dynamic Diving of a Submarine:

http://www.heiszwolf.com/subs/tech/tech01.html#Static