Gears - Another question

[Guest]

Jonathon,

I don't wish to be

Jonathon,

I don't wish to be rude, however if you already have Norbert's book, and have read it thoroughly, then why are you asking about seals?

There is a whole chapter on seals in that book, and it is straightforward to understand.

I will agree that sections of Norberts book are somewhat 'cryptic' especially if you're from a non-engineering background.

However, most of the book is simple enough to digest, and if you re-read through some of the more difficult sections a few times, it'll sink in eventually, I know I had to do this.

I suggest you get a book out from the library on basic electrical theory, as you seem to be hazy on the relationship between Current (measured in amps) and Voltage.

Power, measured in watt's is a product of Volts x Current(Amps). So in the case of Bob's 12 volt motor, if it's pulling 4 amps at stall then that motor can generate a maximum of 48 watts. A good powerful motor, just what you need in a Disney Nautilus. Incidently, Speed 400 and 500's can pull considerably more power (wattage) but aren't terribly efficient.

To build a successful working submarine from the ground up is a very tricky task, as it encompasses almost all forms of engineering.

It's not to be undertaken lightly, and you need a good grounding in the basics if you're to be successful.

Cheers

Andy

[uss silversides]

Jonathon,

I don't wish to be

Jonathon,

I don't wish to be rude, however if you already have Norbert's book, and have read it thoroughly, then why are you asking about seals?

There is a whole chapter on seals in that book, and it is straightforward to understand.

I will agree that sections of Norberts book are somewhat 'cryptic' especially if you're from a non-engineering background.


However, most of the book is simple enough to digest, and if you re-read through some of the more difficult sections a few times, it'll sink in eventually, I know I had to do this.

[quote]
Well, I've heard that the book is a little outdated (maybe that's not true), so I thought I would ask the board and see what everyone else had to say. I guess you're right though, Norbert already has all I need there. No, I do not have trouble with most of the book, even though it is rather technical.

Now, the motor Bob is using is probably a little too big, isn't it?

I don't know how big his boat is, but most Disney Nautiluses (?Nautilae?) that I have seen are about the same length as my boat, but much wider, etc. So I assume my boat wouldn't need a motor quite that big, right? (I hope not) By the way, I am planning on using a 12 volt, 5.5ah SLA battery.

Jonathan

[Guest]

Bob's boat is about 66"

Bob's boat is about 66" long, quite a chunk of boat to push through the wet stuff!

Too big a motor!?

How so?

He's running direct drive, which means quiet efficient running.

The armature diameter of the motor armature is getting on for the diameter of the prop- which means you have a very good torque moment.

In other words, the motor is going to have an easy time of it cranking that prop around.

You can use a small motor, that revs high and gear it. Personally, I only go down that route when I have no choice i.e. not enough space or reserve bouyancy for a bigger motor.

Model aeroplanes are another genre that benefit from using small motors and gearing- in that application the weight advantage far outweighs the loss of efficiency in the drive train.

Using a 12volt system is good plan for a model sub. Far superior to 6 volts- smaller diameter wiring, better BEC, wider range of possible motor combinations, less taxing on on the batteries (doesn't need to pull as much current for equivalent power). 5.5Ah capacity sounds okay, if a little on the small side.

Mind you with a gas ballast sytem you don't need to worry about any additional drain on the power reserves (i.e. piston tanks or compressers/pumps)
----------------------------------------------------------
Only the electronic side of things in Norberts book are outdated. Plus many of the circuit diagrams and schematics are terrible.

I know a few of the projects don't work at all, as a fair few folk have tried building them and the designs needed several modifications before they would work adequately!

The mechanical side of things is completely up to date- there are only so many ways of keeping a sub watertight after all, and they're all covered in his book.

I personally felt that Norbert dwells too much on Piston tanks as the panacea of model Submarine ballast systems. Undoubtedly the piston tank has the advantage when it comes to proportional control, but it has it's drawbacks too, and those weren't highlighted in the book.

There are a couple of excellent systems that get barely a mention.

Also a lot of the mathmatical formulae are poorly laid out which can make things tricky to work through.

However ,there is no other publication to rival this one, and it still stands as the best reference for scratchbuilders and kit bashers alike, several years after it was first published.

Cheers

Andy



Edited By Sub culture on 1070796801

[seasub88]

A really simple answer to

A really simple answer to your question is to go to page 94 in Micro-Mark catalogue motor and adjustable gear box for $24.95 try Micromark.com for catalogue. Be very carefull
using this catalogue. You could go broke buying all the goodies. luck..Jim

[uss silversides]

Andy- I'm sorry, I should

Andy- I'm sorry, I should have been more clear. I meant that Bob's motor would be too big for my boat; my apologies. As far as the gear drive, I would love to drop it all together and use direct drive if it weren't for a lot of guys telling me the best route is a 3]http://www.subcommittee.com/forum/icon_question.gif[/img]

As you know, one thing hinges on another]http://www.subcommittee.com/forum/icon_question.gif[/img]

I sure am giving you a workout with all these questions!

Seasub88- I've been warned of this before

[bob the builder]

... I changed my mind

... I changed my mind when I found that a 6 volt battery would fit with Greg Sharpe's cylinder much better. ...

Make sure that you don't put a sealed lead-acid battery in a sealed WTC compartment.

I've heard of bad things happening when the battery vents it's gases into the WTC.

KAABLOOOOEY!

I'm sure that others on this board could expand on that statement through first or second hand experience.

[uss silversides]

Yes, I've heard of that

Yes, I've heard of that too. I plan to mount the battery outside the cylinder. Thanks for the warning!

[Guest]

Hi,

Electric motors found in automobiles

Hi,

Electric motors found in automobiles come in a variety of shapes and sizes.

Think of all the things on a modern car that use power-

Wipers
Heating (fans)
Air con
Windows
Radiator cooling fans
Seats.

I would get yourself down to the local bone yard and take a peek at whats on offer.

Cars I would suggest looking at are European, and preferably English or German manufacture (i.e. Austin Rover, Volkswagen, Mercedes, BMW etc.), I can vouch for the electric motors in these brands.

An electric motor from a window winder would probably suit well, they tend to be smaller than others mentioned.

Remember, with regards to gearing, what you are trying to achieve. By gearing a motor, you are converting RPM into torque- effectively you are increasing the leverage of the motor to crank the prop round. At the same time you are optimising the RPM for the size of prop you are using.

With one of the afore mentioned motors, you already have lots of torque and they are designed to rev fairly low, usually in the 2000-5000 RPM range, absolutely perfect for scale marine use (not so good for fast electrics).

Most modellers use Mabuchi motors, and their ilk, because that's what they know is available.

Plus some modellers are not interested in experimenting, they just want something that will work straight off the bat, and so tend to copy what others have done.

Kit manufacturers use these motors (i.e. D & E, OTW etc.), because they need to have a source that can provide a consistent supply of the same type of motor.

When you are 'growing' your own unique WTC, you can afford to be a little more self indulgent.

Go with what you feel most comfortable with.

Cheers

Andy

[anonymous]

Absolutely right - very good

Absolutely right - very good advice.

A suggestion also - do have a look at surplus or secondhand industrial motors. There must be some dealers in the US.

We are well served by a dealer here in the UK - Model Motors Direct. Unfortunately they don't have a website.

These type of surplus motors are often of very high quality and low price and often suitable for direct drive. I've been impressed by Buhler motors, for example.

[uss silversides]

Thanks for the great advice!

Thanks for the great advice! I think that I'll be able to find a good motor quite easily now. Any advice on the battery? I think I want a 12 volt battery, but not sure about capacity. I could always use one small battery, and when that one runs dead, I can use another. Just a thought.

Jonathan

[Guest]

If you use one of

If you use one of the motors suggested, you'll find they only draw about 1/2A under load, so that equates to about 11 hours of running under ideal conditions.

Even if you half that, I think you'll get bored before the battery runs out, don't you?

Personally I size batteries for about an hour or two of running. After that I want a cup of tea!

Andy

[uss silversides]

I think I like the

I think I like the sound of these motors Thanks!