Question from Derek - Motors

[Paulrjordan]

I received an email from Derek in Australia on an admin matter, but in
it he also wrote:

"spending most of this Easter Monday steaming cedar planks &
then gluing & nailing. Planking to Decoy (hull) is about 80% now - I
will get some digital shots after hull is complete - I am sure you
know the old adage "a lady is never to be photographed unless her
below water lines are correct"

I have noted in your comments and web pages your preference for low
speed motors (and method) of spring tension alignment facility (same
as the basic try-pod or wheels from older Renault cars) - prey tell,
what type of motors do you use? "

The selection of the paddle wheel engines for my 30" "Director"
sidewheeler tug was really an easy one. Any pair of matched motors
which didn't rev at more than 10,000 rpm at 6V, since a 5:1 reduction
would deliver the desired paddle shaft speed of 180 -200 rpm at full
throttle. They also needed to fit inside the hull ABEAM of each other
and to not draw a great current under load. I put the word out in our
Club , and a member came up with a perfect little pair of old 12V
printer motors (probably out of two separate printers). My
introduction to belt drives was accidental, since it was virtually
impossible to remove the pulley wheels already on the motor shafts
without the risk of damage to the engine. I therefore set about
looking for appropriate belts and building my own pulley wheels (see a
previous post). The motors I found revved at around 12,000 RPM at 6V
and which didn't make them particularly slow at 12V. I found a unique
way of building my own lightweight pulleys in any diameter and
experimented with a number of different sizes eventually settling on
6:1 reduction.

I'm told that VCR motors and Sony Walkman motors all work well for
paddlewheelers. I really don't think we're talking a lot of torque
here. The motors should be a light as possible.

I'll take some photos of my set-up so you can see how they fit into
the general arrangement of the boat. Anywbody else got thoughts about
ideal electric motors for Paddle boats?

PJ

[Derek Warner]

Thanks PJ - but this is where I am coming from

Ten thousand RPM divided by a 5 : 1 reduction = two thousand RPM - do I miss
a ten fold further ten fold speed reduction to get to 180 > 200 RPM?

As you will have noticed I have finally signed (been accepted by Yahoo) and
that is great and even found myself as a member of paddleducks in the
members listings and constructors etc

In my short time with Paddleducks I sometimes wonder where you get the time
to moderate the group, lest answer many of our many questions?

But for all other paddlebucks, please what sort of electric motors do you
use?

regards - Derek

[Paulrjordan]

OMG, Derek~!!! Something TOLD ME.."don't post that message till next
day"!! it was late and I was far too tired to be thinking about model
paddle ship motors.

REMOVE A ZERO!! . The motors I obtained were 1,000 RPM motors at 6V
and would be approx 2,000 RPM at 12V.

Here is the motor spec:
MATSUSHITA ELECTRIC - 13.2 VDC - MYT-6AE5C 4724OB

From all the Paddlewheel motors I've seen, I like these the
most..good torque, low revving, and low amperage. These will "air
spin" the paddles at max speed for about 7 hours on a pair of 6V
mobile phone batteries before any noticeable voltage drop. They'll
also run about three hours under load at full throttle in fresh water
before significant slowing! However I dare say there are MANY other
low rev motors that that would do the trick.

BENCH TESTING
I believe this is the real secret of a successful model paddler and
should be done ALMOST BEFORE YOU BUILD THE HULL. Run motors
by themselves without paddles to get some idea of battery discharge
rate and duration. Then build a simple two bladed paddle to act as a
rotation speed guide (mine was a bit of carboard stuck through a slot
in a piece of shaft tube. This will enable you to set up your gearing
and judge how fast your paddle shafts are turning. Add the REAL
paddles (always a great occasion), and "air spin" them to
check alignment/symmetry and start working with your optimum
speeds/gearing/efficiency. By the way on a sidewheeler..consider
building your paddle shafts fairly beefy (stubby) they don't need
support at their outboard ends inder the sponsons.

The time spent on a bench tested rig will save you SO MUCH GRIEF when
it comes to installation in the hull. Once you have everything working
at the right efficiencies on the workbench (easy to conduct all your
gearing and drive experiments there) all you have to do is pop the
rig right into the boat. Make EVERYTHING REMOVABLE and MODULAR. I can
strip my entire side paddler to a bare hull in about 5 minutes and
reassemble it in 10.
(Holler if you need more insight into MODULARIZATION!..I call it my
"Plug N' Play" system) REMEMBER the TWO things to keep down...WEIGHT
and WIRING!!

Something I've noticed on model paddlewheelers is that their motors
tend to be a little "heavy duty" for the application. Maybe it's the
size of the paddle wheels that intimidates builders, but it actually
takes very little power to turn them in scale conditions, especially
if your shafts and bearings are well designed and built.

WATER TESTING
When you have the HULL and all its mechanics in place you should
BATH and SEA TEST the heck out of it. I spent literally hours running
the boat without any RC equipment with engines hooked up direct to
batteries and manually set the rudder so I wouldn't lose it! I
recorded copious notes of weight/waterline level/rotation and
plunge/running speeds/battery efficiency and a whole host of things
before I even started on the superstructure. These notes sent me back
to the drawing board many times. (something you WON'T have to do,
because I've MADE ALL THE MISTAKES...right up to getting the boat
stuck in sheet ice for half a day!!! (remember to cover the paddles
with something when you're water testing, as the aquatic fountain
display can be quite impressive!)

WEIGHT and C of F
When you have the ship behaving exactly how you want on the water,
remove all the ballast weights you put in..and weigh them..this will
give you an IDEA (only) of the weight you have left for the r/c
equipment and superstructure..but REMEMBER C of G, it's critical in
ANY Paddler. I'm convinced it HAS to be somewhere below the paddle
shaft axis..but I'm not sure how much lower it can be before causing
other problems. You'll soon know if it's WRONG..if it's too high, your
side paddler will positively waddle through the water and heel
alarmingly on sharp turns!! The "Mt. Washington" sidewheeler kit
(lovely looking model) apparently suffered from this and modelers had
to build the most ridiculous "keel type contraptions" below the water
to stabilize it.

> As you will have noticed I have finally signed (been accepted by
>Yahoo) and that is great and even found myself as a member of
>paddleducks in the members listings and constructors etc

WAY TO GO, Derek....now you can look at all the archived material in
our FILES, BOOKMARKS and DATABASE. Feel free to add to these
yourself..theyre there for EVERYONE to ADD to!!


> In my short time with Paddleducks I sometimes wonder where you get
>the time to moderate the group, lest answer many of our many
>questions?


Late at night, early in the morning, and a few "look ins" during the
day when I'm in the office here at home. HOWEVER, the next 10 days
will be a little hectic for me at work and you won't be hearing too
much from me..but I will be checking in every day. We have so many
knowledgable people here in Paddlducks and also through our "sister"
forum with Mike at Modelboats..there probably is NOT ONE QUESTION
THAT can't get answered!!

So keep on PADDLING!!!

PJ