RCABS I'm over it

[redboat219]

OK.
Mike posted a query while back asking instead of blowing gas into the ballast tank can you use Propel blow up bladders. Well here's mine, why not use the snort system instead, with the badders located outside the subdriver akin to RCABS together with an internal non vented tank?

[Albion]

OK.
Mike posted a query while back asking instead of blowing gas into the ballast tank can you use Propel blow up bladders. Well here's mine, why not use the snort system instead, with the badders located outside the subdriver akin to RCABS together with an internal non vented tank?

Thats basically the same as the Propel / snort system but without the propel. plus smaller WTC (ie shorter), minus there needs to be space for the bladder, so its swings and roundabouts.

Vs standard RCABS
Plus, no strain on seals, IE WTC stays neutral pressure, minus needs to be trimmed for the snort to be above surface when dived.

Personally i find that even with a cramped WTC there is enough volume of air to inflate a bladder without putting strain on the seals, and if you have the propel system , you have a backup as well, so doesnt seem to offer any benefit over what is aklready out there.


I think at the end of the day, you build what works for you

[Slats]

......
Personally i find that even with a cramped WTC there is enough volume of air to inflate a bladder without putting strain on the seals....

Albion - I have heard many people state this but my RCABS test found the opposite.

Part of my testing involved using a standard WTC (decked out with gear mtrs etc and push rods) as the bag's air supply. I observed 2 things.

First is the bag inflation caused such significant vacuum that I had a leak in a push rod seal (that had never ever leaked before).

Secondly I am sure quite a lot of people use in the WTCs a valve to release over pressure when closing the WTC end cap and use this valve again to pump in air to release the end cap and open it up post mission. The RCABS vacuum was so strong that a leak occurred through this valve! I might point out the valve leaked first and the push rod leaked second.

If a RCABS air supply is intended to make use of the mechanical WTC section with all of its linkages through the end cap, I cannot see how a valve can be employed to release slight overpressure when sealing the WTC and for the WTC ease of openning later as doing so I believe poses a leak point.

Bottom line is I don't buy the overarching statement "there is enough volume of air to inflate a bladder without putting strain on the seals". I think people who find that this is the case, just happen to have "the right combination" of size of airspace, type of seals, layout, specific pump, and bag size. And this is another fundamental problem with RCABS is I am yet to find where this specific "right" combination is obtainable. That is there seems to be a degree of luck in the engineering setup getting this right.
You could potentially buy all the gear and end up with a mess on your hands.

My final evolution of my RCABS experiment used a separate airspace - nothing inside it except the pump and clippard valve. This was a risk strategy, in my view necessary for this system and a key limitation.

Compare RCABS to a gas boat, there is no luck factor required- you know exactly what quantity of ballast is on board, you know where the ballast is located, you don't put a boat to sea where the engineering space could be compromised by unmeasurable / uncertain internal pressure on seals. And most importantly you know how it will work and that it will work as intended prior to buying.

[redboat219]

What I meant was, instead of using air from inside the WTC (as in standard RCABS) to inflate a bladder you'll use the snort pump. The bag is equipped with a vent valve to release air during submersion. So basically instead of a fixed wall ballast tank you're using a flexible one.

[Slats]

What I meant was, instead of using air from inside the WTC (as in standard RCABS) to inflate a bladder you'll use the snort pump. The bag is equipped with a vent valve to release air during submersion. So basically instead of a fixed wall ballast tank you're using a flexible one.

Gotcha - but my point re Albion's quote still stands.

With this situation you described above your using the snort pump as an onboard aircompressor - that is everytime you are either on the surface or in snorting range (PD with a snorkel) you replenish the air in the air reserve bag right? Its a nifty idea - but you need to place the bag somewhere in its ready inflated stated where it does not displace any water, else the inflation of the bag will make the boat lighter where as you want the opposite,you want the contents of the bag to blow the tank. If you put the bag inside a cylinder so as to not have the inflating or inflated bag acting on displacing water, the cylinder will be under positive pressure as the bag inflates and whilst the bag is inflated.

I can see some good thinking here and some complexity in solving the problems that might make this not as viable as other tested methods.

If you could some how use the snort pump to double duty -that is; blow the tank at snorkel depth; and compress air into a pressure vessel to be used to blow the tank at depth - that would be very cool indeed.



J

[Albion]

Secondly I am sure quite a lot of people use in the WTCs a valve to release over pressure when closing the WTC end cap and use this valve again to pump in air to release the end cap and open it up post mission. The RCABS vacuum was so strong that a leak occurred through this valve! I might point out the valve leaked first and the push rod leaked second.

By valve you are talking Tyre valve, so yes a small vacuum will open that up and leak. Second what seals do you use? or more importantly which way round do the cups face, again that will leak like a sieve

I dont have a valve, it makes closing and opening a bit tough but not a major engineering feat, plus I'm using bellows seals on the push rods. If you want to release the over pressure then a screwed plug or on off type valve would be best. Clearly you have got an issue with this design and are more than happy with Gas/Snort, so i'm not going to try and convince you one is better than another as we all have different objectives and ideas. YMMV :)

My RCABS is on a 1/96 Permit, i had been working on my own piston system which was giving a few problems, and found with what i had lieing around I could quickly produce an RCABS and get it back in the water. This i did and it operates very simply, whats more i found that despite the bag only patially inflating it was giving me a great scale waterline on this vessel. I'm sure it wont work as well for all though. I had planned to use the RCABS as an interim, but it just works so well on this boat, its going to tkae a lot to make we rip it out. I do leave the piston tank sat on my bench so everyday i have to look at it and be reminded i failed so far.

[Slats]

Albion,
I have never denied that RCABS doesn't work - in fact it did for me as per my original post in this thread....its just to me for the reasons I outlined a poor choice of system when I have alternatives.

And heres the main rub - it seems more or less a hit and miss approach.
Get it working fine - great- the reviews are all over the net, but the net does not seem to have a balanced view of the cons of the system.

I don't doubt that some love it - good for them!

Whilst some criticise gas as complicated plumbing the basic principles of free flood tank and expelling the water via gas injection / snort are simple. RCABS I find ain't that simple at its core.

I have been using a sealed tank and different pumps for years - gas /snort works a bit better than the setups I have mucked about with, but both systems IMO are superior to RCABS. I am now revisting pumps in combo with free flood and snort.

As Skip once told me regarding ballast systems - there are many ways to Southern California - so true!

I might also add that the RCABS boats I have seen running well all consist of US type nukes, a 212 and a few U-boats.
I am sure there are others too, but could it be a common theme amongst these boats that they all share perhaps little reserve buoyancy?- When I got recently excited over the very small ballast tank a friend of mine fitted to a 1/72 scale LA that both submerged the boat and achieved a scale water line, David posted about how little reserve bouyancy US nukes have and therefore don't make generalisations to other types. I mention this as you states your 1/96 Permit needs only the bag partially inflated. On my Collins I needed a 9 inch bag at near bursting capacity - quite a difference! Collins class boats have a 32% reserve buoyancy, I understand most US Nukes have around half this.

There seems to be a consensus that RCABS is not suited for all boats. If this latter point is indeed the case then the only logical conclusion that I draw from this is, the RCABS methodology is not simply replicable for all boats.
Gas and other pumps systems are.

I respect your position - I guess we have to just agree to disagree.

[He Who Shall Not Be Named]

Good discussion so far. Lots of good points presented and argued.

But, where's the blood-bath and the name calling ... I want to see bodies, burned black, heads rolling on the floor, guts smeared on the walls, family trees challenged, etc.

What's wrong with you people!? ... can't get it up? DING!

Anyway.

John, sighting my initial observation, hit on RCABS major liability: For a given submarines internal volume, the system is able to provide enough displacement for a low researve buoyancy boat, but can not (without taking up almost every available cubic inch of internal real-estate with a bag or bags) produce the displacement required to get a high freeboard boat to the correct waterline.

As proof of this: Three Revell GATO kits at a SubRegatta, each built by a ****-hot r/c model submariner. Mine had a gas/LPB ballast sub-system, the other two guys used an RCABS ballast sub-system. Only mine would attain the correct surfaces waterline, the other boats, in surface trim, were almost decks-awash -- nowhere near designed waterline.

Prosecution rests, your honor.

David,

[Kazzer]

But, where's the blood-bath and the name calling ... I want to see bodies, burned black, heads rolling on the floor, guts smeared on the walls, family trees challenged, etc.


David,

Yeaaaaa! Wot he said!

[Slats]

Ok you want some blood eh....

To the arseholes who perpetrated the lie that RCABS is the **** hot default system that all should be using: Foxtrot Uniform Charlie Kilo you.

To date I have spent close to $600 on pumps valves, enclosures and what nots -some of which can recycled for other non-RCABS applications such as a helicopter lift on my Krivak III frigate - most is money that is gone now for good. - On the upside least I learnt something - but there are far cheaper classrooms.

I am exceptionally ****ed that I spent money on fundamentally the lie of widespread "net literature" - to this end I blame the masturbating burger flippin morons of the net - and myself for not investigating further. In my defense the weight of the chorus of pro RCABS advocates is rather loud and didactic. It features previously what I thought to be credible long standing players in the RC sub game.

This poor advice to the new guy is nothing short of shameful. There will come a time when some new guy or perhaps someone like me in the future will get burnt and will insist on a refund for the gear that is unworkable in his / her particular sub.. When the vendors - quite rightly say its buyer beware - are you ******s who keep pushing this ****ty dead horse going to step in make good???? I didn't think so. So unless you have something to contribute based on extensive testing and sound physics STFU - (wow I'm learning this 4 letter acroynm stuff).

Enough floggin this horse!

Happy

- Slats!

[roedj]

John,

ROTFLMAO

Dan

[He Who Shall Not Be Named]

Well done, my young sith-loard-in-training.

David,

[Kazzer]

THAT is more like it John!

Thank you for those few kind words!

I guess it's official now -- RCABS sucks!

Damn! I've still got bladders in inventory! (Shot myself in the foot over them eh!)

Maybe we should have a clearance sale on them?

[He Who Shall Not Be Named]

THAT is more like it John!

Thank you for those few kind words!

I guess it's official now -- RCABS sucks!

Damn! I've still got bladders in inventory! (Shot myself in the foot over them eh!)

Maybe we should have a clearance sale on them?

Hang on to those things, Mike. Might use them as trim tanks for the bigger SD's. I've got ideas:

A small bag at each end of the SD, with a tiny, small volume peristaltic pump between 'em, and another low volume peristaltic pump feeding/emptying the bags from sea, that sort of thing. Two bags, two small pumps giving the ability to both change weight (hovering tanks) and shift the c.g. (trim tanks).

Keep 'em in stock, Mike -- those smaller bags are solid gold!

David,

[Slats]

Mike,
re the pumps too - have been mucking around with target stuff....i.e. WW2 depth charge thrower. I won't give you all the details in case someone takes their eye out trying - so don't.

The RCABS pump and bag combination works a treat too at inflating underneath a threaded clear rod connected to a scale chopper with motor inside. Effectively as a gimmick device on a target carrying a helo you power the chopper up with an ESC with pwr leads connected to the on-board motor being very fine brass on the outside of a clear acrylic rod. The rod goes into a sleeve and can move through a vertical plane raising and lowering the chopper via the RCABS bag pushing the rod up and lowering it via inflation deflation cycles.

Other uses involving RCABS principles of getting air from a chamber (not one with push-rods or equipment) are using the pumps to raise and lower scopes - again a gimmick device only - some like it.

Guess what I am saying is there are many uses for these components.

J