RCABS The History

[kazzer]

Some years ago I purchased an S Class submarine from Metcalfe Mouldings UK, and was supplied with a drawing of the workings of the boat. This drawing was done by Darnell and is, by my best guess, dated circa 1950.

Here is a section of the drawing/plan -

http://forum.sub-driver.com/picture.php ... tureid=169

Except for the fact that Darnell had designed a box with a bolt-on lid instead of a WTC, this diagram is exactly the same process as the current RCABS systems being touted today.

My question is, who deserves the credit for this 50+ year old system, the Englishman Darnell?

[kazzer]

Actually, isn't that an RCAB-R

Actually, isn't that an RCAB-R system?

Look carefully at the drawing and you can see the bladder (an old soccer ball bladder, I believe) was connected to a tank in the bow of the boat!

Well, well, well!

[Guest]

You're almost right. John Darnell

You're almost right. John Darnell used a small USE steam engine as a pump, air was moved from a bag(s) to a GRP reservoir, usually located in the bow of the submarine. To surface the pump was reversed. So the pump had to be used both ways, and the system was very low pressure and therefore slow in operation.

The USE pumps, not really designed for this application were rather leaky and poor in efficiency, so model submariners in the UK started to modify the basic system.

The USE pump was replaced with a tyre inflater compressor, which can be picked up inexpensively. The motor was usually swapped out with something smaller and less thirsty. A servo controlled valve was installed, and the air was now held under pressure in the GRP tank. To surface the air was released back into the bag via the servo controlled valve.

This is effectively what you folks call RCABS-R, and has been in use here for at least 30 years.

Most submarine modellers here in the UK now use water pump systems with fixed tanks. Why? Well good quality water pumps are easy to obtain off the shelf, the fixed tank doesn't give trim problems, which bags and cuffs sometimes can, and the system is efficient and cheap- you can build a water pump system for most boats for well under £30.

The introduction of the very tiny diaphragm compressors may give a new lease of life to compressed air systems. These weren't easily available until recent times, and their diminutive size makes them suitable for use in smaller boats, something that wasn't feasible years ago, unless you had the tools and skills to make a custom pump.

[kazzer]

What's more, would you believe,

What's more, would you believe, the detail is further enhanced in the drawing here


Well, chaps! this IS a turn-up for the books! Seems like our allies are up to their old tricks again!
Come over to Blighty with their darned nylons, cigarettes and chocolate and steal all our good women, then snaffle all our good ideas too! That's just not British you know!
Never mind men, we'll keep a stiff upper lip and soldier on!

[kazzer]

Seems old Darnell had some

Seems old Darnell had some other neat ideas!

Just look at this 'cork and fishing line' marker buoy!

http://forum.sub-driver.com/picture.php ... tureid=170

[Guest]

There is nothing new under

There is nothing new under the sun. We're just pushing water around from point to point to increase or reduce the density of our vessels.

Here in the UK, you will be regarded as lily-livered if your boat cannot statically submerge. We even have a trophy for the best boat that can hold the best statically submerged trim.

[kazzer]

You're almost right. John Darnell

You're almost right. John Darnell used a small USE steam engine as a pump, air was moved from a bag(s) to a GRP reservoir, usually located in the bow of the submarine. To surface the pump was reversed. So the pump had to be used both ways, and the system was very low pressure and therefore slow in operation.

I wondered what that was in this drawing. As I was going for a D&E Sub-driver, I never paid much attention to this part of the drawing before!

http://forum.sub-driver.com/picture.php ... tureid=172

Yep! There it is, the little piston steam engine!

[Guest]

So, Subculture, what you are

So, Subculture, what you are saying is that Darnell's system used a model steam engine for a pump, and used a pressurized reservoir?
I had not heard of his system when I devised, perfected, helped popularize, and named my system, RCABS, which used a miniaturized electric pump, and recirculated air from the watertight compartment, without an auxiliary pressure vessel. So, Kazzer was almost right? Does that make him wrong?

[Guest]

Yes it would have been

Yes it would have been mildly compressed in the reservoir. Very low pressure though, a few psi at most.

Some people did away with the auxiliary reservoir and used the air space in the box, and if I recall correctly the Darnell Biber did this as it was a smaller boat and lacked the space for a separate reservoir.

Nick Burge later incorporated a recirculating compressed air system in a cylinder. This used a twin cylinder piston compressor which drew air out of a fixed central ballast tank, and stored it under pressure in the forward compartment. The tank was vented at the bottom so as the air was sucked out, water was pushed in. Probes mounted in the tank detected the water level, and shut down the pump before it started taking in water.

To surface the pressurised air was released by a servo operated valve. The main problem with this system was cost.

The purpose built compressor was an expensive item, and the electronics used to monitor the water level added more cost. Nick later worked with Dennis Cater on pressurised water pump system, which is the system used on the Sheerline range of boats. This dispensed with the pricey compressor and electronics, and is widely used here in the UK.

The idea of RCABS pulling a vacuum in the cylinder was something I hadn't seen. Most model submariners over here would shy away from that, because it requires low power to submerge, but a lot of power to surface. The RCABS-R is a better principle in that it reverses this.

[Guest]

These are the images Mike

These are the images Mike was trying to upload. I think the problem may be that the account that you are trying to link to is password protected?

The images show the bag at the front, they usually had a bag at the rear too. This made for an interesting time trimming the boat, so most modellers split the watertight box into two sections, forward and aft, and placed the bag in the middle over the C.G. This worked well.

[bigdave]

I like your comment Andy,

I like your comment Andy, "There is nothing new" No reinvention of the wheel.
When Crazy Ivan told me about using the R system he and I said all along that someone had done a similar system before.
Just a different take on an old system.
It worked then and it works now.
I actually have a few of the Unit steam engines in my hobby collection.
I have been thinking about doing some articles in the SCR about some of the older sub kits and ballast systems. I have quite a collection of model sub info I have collected over the years.
Hey Pete!! You got mail!! BD.

[crazy ivan]

Just to set the record

Just to set the record straight; from The SubCommittee REPORT, Issue 69 June 2007 page 28]While I did arrive at this idea on my own, I cannot claim to be the first one to build a system that moves air from a ballast tank into a pressure vessel to be re-circulated back later. Indeed, I’ve learned that British hobbyists used systems like this for many years. Those systems used converted steam engines or automotive tire inflators to do the job. What makes Reverse RCABS (and original RCABS for that matter) unique is the implementation.[/quote]

[Guest]

I'm just not interested in

I'm just not interested in engaging in a bun fight over who came up with what when and how.

I've just pointed out the development of low pressure compressed air ballast systems here in the UK.

John Darnell is largely credited with popularizing R/C model submarines here in the UK. He was the first to come up with affordable kits which enabled a modeller of reasonable ability to put together a working submarine for a modest cost. Bear in mind this was a long time before the advent of the internet, so individuals were often working in small groups or in isolation- information was very difficult to obtain, limited to a few articles in magazines etc.

[bigdave]

Don't ever stop Andy. http://www.subcommittee.com/forum/icon_wink.gif

Don't ever stop Andy.
It is always good to know where we came from in the world of R/C subs.
History Rules!! BD.

[chuck chesney]

Andy, you are spot on

Andy, you are spot on regarding the utter futility of trying to assign historical precedence to any model submarine technology. I have an issue of Model Airplane News from 1957 that talks about a balsa wood hulled, dry hulled, one channel, RC model submarine, built by a man named "Brother Otto". It was a pump boat, much like the so called "snort boats"...but who cares? The whole discussion is really sort of like debating how many angels can dance on the head of a pin...a total waste of time.
Also, you are absolutely correct about the Dark Ages before the Internet. There were isolated individuals and very small groups toiling away like mad monks, with virtually zero communication between them, and re-inventing the wheel.