sub newbie

[thordesign]

Jason,

First of all, we have

Jason,

First of all, we have earned our "place" in this world the hardway and do not need to apologize or "humble" ourselves to anyone for our accomplishments. Yes, the Europeans have made substantial contributions to the hobby, no arguement there. Enough politics...

Now, to the engle tanks. Ok, lets assume that they have sold these tanks in the numbers that they are professing~30,000 worldwide. If I am not mistaken they have been available for more than 20+ years now. They are not a new invention by any stretch. Figure the numbers yourself 30,000/20=1,500 per year.

Put that in context of years manufactured, that is not a large number at all, because this is not a large market. Those numbers prove that this is not a large market and this never will be a large market. You and I disagree on this point so there is no point in arguing over it.

The American or home grown versions of ballast systems came out of the use of the Engle systems and their inherent weaknesses in certain applications. Please understand I am not bashing them. They certainly have their place and application. I have used a couple myself and was not happy with them. They tend to have some serious drawbacks for some modelers like me.

First, they draw LOTS of amps. You are compressing air, which takes a certain amount of KW to reduce its volume no matter what volumetric displacement system you are using. They are extremely inefficient energy wise as well due to the very tight seal required on the walls of the cylinder which translates into a tremendous amount of drag to overcome no matter if you are using a screw or rack system. It does not matter.

Second, they are not volumetrically efficient. Which means your model must be large to be able to accept the compressed air from the cylinder. This presents its own set of technical difficulties as well trying to contain the air through seals, stuffing boxes, and other pressure hull penetrations. If you are a large model fan, then this is not a problem. If you are a small model fan, like me, than this system is probably not going to work well for you.


Third, due to the above reasons, your model will be fairly heavy due to model weight and battery size. I have had one hernia surgery already. I desire to never have another.

The finest model I have ever seen using this system is Mike Dory's Type IX. It is an absolutely magnificent model. Mike had it working to perfection.


The finest design I have ever seen for a compression system is John Slater's Permit. John, one of our SC members from Australia, has honed his system down to a trouble free system that does not use a cylinder to compress the air, but a water pump, which rids the systems of the enormous amp draws that the engle systems require. Take a look at his article in the SCR a few issues back.

Myself, I prefer the more compact WTC type ballast system first introduced by Dave Merriman as a production item. It fits my style of modeling more than any other sort.

OR

Skip Asays ballast system for his line of kits is a study in simplicity, efficiency, and reliability. I like it very much.


After more than 20 years of active modeling R/C subs and building dozens of subs, I would choose one of the WTCs or Skip's type of system over any of the others. But, that is just my opinion which counts for absolutely nothing...

You asked where is the market going?

Well, the market will go where it will. A few people will buy engle tanks, a few people will buy WTCs, and a few people will build there own. R/C submariners are an extremely small group when compared to the R/C hobby as a whole. It is a bit of an obtuse hobby. I believe it always will be...

Europe is a VERY different place than the United States. If you have been there you probably know what I am talking about. It is not fair to compare the two without discussing LOTS of different cultural issues that lead them to spend more time on hobbies than Americans. That is a seperate discussion and has no place on this forum.


Hobby Shops-Well I was in the hobby shop that I patronize just yesterday. They had 2 Robbe U-47s on the shelf and had a small inventory of the Dumas kits. They, also, have the new Krick U-boat on order. Most large hobby stores I have been to in Texas, Oklahoma, and Kansas in the last year have these kits on the shelf. Most hobby shops stock what sells. They have sold a good handful of the Dumas kits and a number of the Robbe kits over the last several months.

As I said above, that is just my opinion which counts for absolutley nothing...



Edited By ThorDesign on 1084406498

[anonymous]

Matt Thor, bravo for you!

Matt Thor, bravo for you! As a guy who has risked money and time in this hobby, your opinion is very much valued. I have an old (circa 1978) Engles Patrick Henry. It was the only working sub kit that I could find in those pre internet days. It had two piston tanks in it, and was not only VERY heavy, it was a battery hog. The piston tanks took up an inordinate amount of space in the hull, and the need to seal the whole thing was an ongoing pain and problem. Pure and simple, it is thirty year old technology.
I am in the final stages of doing a major rebuild...wet hull, WTC and Art Broders RECABS system (the air pump draws 20ma when pumping). Modern technology.

[Guest]

Chuck,
That little 6V micro air

Chuck,
That little 6V micro air pump is quite efficient, but it is not that stingy. It typically draws from 200ma, up to 380ma at full load. It reaches pressures of about 15lbs/sq" which feels really tight when the bladder is wrapped around your arm in a blood pressure cuff. When used in the RCABS in a model sub, it can easily bring the model up from 10-20 ft. depths.
Art

[safrole]

Thanks for that, Matt! You

Thanks for that, Matt! You act like I don't value your opinion, which is untrue, if a bit dramatic. And if it seems like I'm a piston-only drone, that's also not true. I'm just looking to make some sense of the two schools of thought and you have made your side pretty clear, even if it was a bit dogmatic.

I also don't mean to take away from American advancement of the hobby, which is considerable. My use of the word 'humble' is only meant in the context of overconfidence, not to humble ourselves BEFORE anyone, as a servant. (Pride goes before the fall.) A humble person makes less assumptions about their own importance and SC can sometimes be an unfriendly place for "dissenters". (shocking, I know...)

I do confess I was hoping for some little concession from you on the piston tank's viability, since it must have SOME merit. It's hard for me to swallow a hard-line view in the face of their sales figures. Even if your massaged math is correct, that's a lot of tanks. That's a lot of people who did not believe the "new" technology was necessarily better. Now don't get all worked up - pumps and gas and especially that RCABS are the better choice in many situations. (I fully intend to try that RCABS when I get some time!) I just don't think it's possible to dismiss the piston tank outright as an obsolete relic. This is especially true as Frank comes out with a new generation of depth controller that will do something that none ever has before. I find that very exciting.

Plus there's probably a lot people out there reading this discussion who are not going to post. I hate to see anyone get herded down a path like so many sheep just because there was not a clear and open discussion of the merits of different systems. I'm sure we all agree on that point.

So, throw me a bone, here. Tell me why you think the piston tank, given its shortcomings, is still a strong seller in today's market.

Anyone can answer.

[Guest]

Matt Thor, bravo for you!

Matt Thor, bravo for you! As a guy who has risked money and time in this hobby, your opinion is very much valued. I have an old (circa 1978) Engles Patrick Henry. It was the only working sub kit that I could find in those pre internet days. It had two piston tanks in it, and was not only VERY heavy, it was a battery hog. The piston tanks took up an inordinate amount of space in the hull, and the need to seal the whole thing was an ongoing pain and problem. Pure and simple, it is thirty year old technology.
I am in the final stages of doing a major rebuild...wet hull, WTC and Art Broders RECABS system (the air pump draws 20ma when pumping). Modern technology.

All methods of ballast shifitng have been done to death many times over in the model submarine community. There is nothing new.

They all have advantages and disadvantages, however one area that has remained fairly stagnant is electronics/automated dive control systems.

Typically systems based on pumps, compressed air (with the use of compressors) and pressurised gas are difficult to control in a proportional manner.

Additionally, they generally use an exposed water surface which can lead to instability and shifting of the C.G due to sloshing- use of baffles cuts this effect to a minimum but never completely eradicates it.

If the bottom of the tank is exposed to water pressure via permanently open vents, the air bubble in the tank will compress, making it heavier and hence out of control unless manually corrected. The fitting of kingston valves would eliminate the latter, but I haven't seen this done yet.

The pressure problem is more of an issue when working beyond a couple of feet.

Piston tanks will generally require a little more juice to operate than a pump or compresser- certainly more than a gas system, but then that isn't a fair comparison.

The gas system relies on regular refills from an onshore supply of potential energy (propel), else on the bottom it remains when you wish to blow your tanks- a back up system is essential IMHO if using gas.

This can soon raise the cost and complexity of the simplistic gas system. Not to mention the expense of propel!

In it's favour, the gas system is simple and very inexpensive to produce (initially) and requires virtually no maintenance. Plus dive and surface times are quick (assuming you have enough gas- tee hee) and you get a nice stream of bubbles.

Piston tank, compressor and water pump systems on the other hand are completely self contained, and with the addition of a little cheap circuitry can be made to fail safe by refusing to dive unless there is adequate battery power.

Piston tanks take up more room, because there is a motor and gearbox to accomodate.
The problem with the extending screwed rods was addressed by Ron Perrot some years back- he placed a seal on the piston so that the piston run up and down a fixed thread. Very compact, but I would consider this system was a tad less efficient owing to increased friction, plus there was the additional risk of the seal failing and causing a leak.

A water pump system has a lot of advantages in regard to cost. It is also simple.

However at present no system that I have witnessed is proportional and trimming your boat to a set depth can be a long winded process that you have to repeat for every dive.

Water pump systems with a vented tank should be trimmed to a positively bouyant state unless equipped with a backup system to blow the tank. Otherwise you are playing Russian roulette with your boat.

Compressor systems generally require some workshop skills, in order to fashion a suitable compressor.

Small boats can benefit from off the shelf components, and tyre inflater pumps can be converted fairly simply- but these aren't of very good quality. Generally, the compressed air system either uses an air bag or fixed tank. These can suffer from the same problems as gas and water pump based systems.

I like all the ballast sytems, except for pressurized gas, which I have never considered a viable system due it's lack of a natural failsafe.

However when it comes down to making a boat that can hang at any depth and which can be relied upon to maintain that depth almost regardless of water pressure, I'll go for a piston tank.

Sub Concepts have an innovative and exciting system here that will suit all sizes of boat.

I think some of you should wait and see how it performs before condemning it.

Andy

[thordesign]

Folks,

Help me out here! Does

[color=#000000]Folks,

Help me out here! Does anyone else come up with a different answer than I did on the math. If so, please let me know. That means I have been doing my division wrong for 40+ years now.

The tank has been produced since 1976, lets message that 30,000/28=1071.428571 units per year.

I can't find a single line where I say the engle tank is NOT viable. I believe I said quite the opposite. The same can be said for any of the systems I discussed.

I am NOT taking sides here. I am a engineer first and a modeler second. I look at everything through the mathematics of the particular design. Life is pretty black and white for me. If it where not I could not be a successful engineer. I take no sides, I let the math do that for me. I have preferences just like I tend to prefer 2 ply toilet paper over single ply. There is a difference. In politics and warfare I take sides...


Dogmatic]



Edited By ThorDesign on 1084483123

[thordesign]

Andy,

I am only speaking about

Andy,

I am only speaking about the past Engle systems, not Frank's system. The discussion is about sale of this technology to date. I have no experience with Frank, his company, or his system and am looking forward to seeing what he comes out with. I have heard nothing but good things about Frank. This is not a critique intended at all towards his products. Your explanation of the various systems above is a very good one. You obviously have your preferences just like everyone else.



Edited By ThorDesign on 1084483259

[safrole]

Sorry about the dogmatic comment.

I'm

Sorry about the dogmatic comment.

I'm not attacking your math, but I'm saying that the argument is only as strong as couple assumptions, like steady sales and exact years sold. I doubt the graph is linear.

I know you're not being political - I am. I want to see the tank get a fair shake. I am friends with Frank (of course) and he is a dogmatic piston tank guy. Of course he defends his position quite convincingly, as do you, so maybe the "dogma" term is again inappropriate. I got to be friends because I bought into his philosophy, which clicked with me immediately. I don't feel I'm alone, and I like getting your opinion on it. I think the two camps can agree to disagree. They are apples and oranges, to a certain extent.

[casey thrower]

I'm just looking to make

I'm just looking to make some sense of the two schools of thought and you have made your side pretty clear, even if it was a bit dogmatic.

Dear Safrole,

Although I have enjoyed your relentless banter, your responses have the tendency to be repetitious, (look it up) and predictable. You are quite talented at constructing unique word combinations to formulate a derogatory and demeaning response. However, these responses give the impression that you are an individual severely lacking in maturity, finesse, and creativity. My advice is to think about what you want to type before you type; and then, don't bother typing it. Lastly may I, at the risk of offending you, suggest that although this little "I Want To Be A Real Flamer" project of yours is keeping you off the streets and out of decent folks sights for a few hours, may I suggest that you hand yourself over to the government for deep dive experiments?

I hope this helps

[Guest]

Jason,

It is good to see

Jason,

It is good to see that you are contributing to the growth of the hobby with your after market brass kits. Further more, you seem to be quite active here on the board, always willing to offer advice which can be of help to new members. I myself, have been a member of the SC since 2001 and it was the great advice on found the "board" that lead me to purchase my first sub, a Robbe U-47 followed by a SubTech Albacore. After those I "stepped up to the plate" with a SMW Kilo, and then on to a ThorDesign Permit, Akula (Improved) and Type XXI. So with that said, I have seen a few different ballast systems. Each one has it's own place and function. From my experience the Piston Tanks available on the markets today really only excel in the larger scale subs because of there size.

Unfortunately, I haven't found a commercially available piston tank system for the 1/96, or smaller scales on the market. For those who like the smaller scales because of space constraints or travel limitations, almost anything BUT a piston tank is the solution. Further more, you must admit that the American Pioneers of our hobby have developed a variety of simple, reliable ballast systems that can be used in any scale, large or small.

Now, you have done a great job on the after market brass kits so I would like to encourage you to work with your contacts to develop and produce a piston tank for those using 1/96, or smaller scales.


More innovation in the hobby is a great thing and is always welcomed.

Lyle Jansma

[safrole]

Thanks for your gentle treatment,

Thanks for your gentle treatment, Lyle. It shows a lot of class. You should call to express interest directly. I just soak up what advice I can. You would understandably have more weight than I. Every product request is a "vote".

Casey I'm sorry I rubbed you (and maybe others) the wrong way. I do find your general abuse of me unwarranted. It demonstrates the very characteristics of which you accuse me.

[Guest]

There are some 'almost readymade'

There are some 'almost readymade' piston tanks for small models- they're called hyperdermic syringes!

The larger versions work extremely well, if you can find someone to supply with new stock. You need to be able to mate these with a small motor and gearbox, and either a rack and pinion or threaded spindle.

Perhaps the reason that the likes of Engel haven't built a very small tank, is possibly that they haven't seen a market for it, until now.

The small scales tend to appeal chiefly to US modellers it seems. Most modellers in the UK tend to prefer 1/48th scale or larger scales, and from what I have observed the same goes for other european modellers.

That having been said, the piston tank system can be adapted to very small models indeed.

The only limit is skill and imagination.

Andy

[safrole]

Andy do you have any

Andy do you have any pics of that rack setup you mentioned?

[Guest]

It's under construction.

Will post some

It's under construction.

Will post some pics when finished, okay?

Andy