Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[maninthestreet]

Often I see scale mode boats with twin motors. If a model was convered from single motor operation to twin motor operation, where the motors are identical, would this have the effect of:

1) Increase in top speed of the model

2) Increase in power

3) A bit of both


Assume the battery voltage in twin motor mode is the same as in single motor mode.

[Shipmate60]

maninthestreet,
If you double the single motor set up you will:

Increase the top speed by 50% if you are lucky on a displacement hull.

Double the power, but the transmitted power is dependant on the efficiency of the prop.

Halve the duration of the battery.

It will however "stabilise" the model at speed and make going astern more manageable and steerable.

Bob

[catengineman]

Are you talking 2 motors to 1 shaft and screw
or 2 motors to 2 shafts and screws?

just to clear things up

R,

[Garabaldy]

also if you have enough channels you can set the motors up to be controlled independantly "tank steering.  Hugely improves the handling of a boat.  On my wimpey seahunter i can shove one motor full ahead, the other full astern and she spins on her own axis.

[roycv]

Hi, assuming 'scale' means a displacement type hull, then there is a speed associated with the length and breadth of the hull which governs the maximum efficient speed.  If a displacement hull is over powered then it can be seen in the deep valley of the stern wave. Hope this helps.
regards Roy

[maninthestreet]

Are you talking 2 motors to 1 shaft and screw
or 2 motors to 2 shafts and screws?

just to clear things up

R,

2 motors to 2 shafts and screws, i.e twin props, each powered by  a separate motor.

[catengineman]

Ah ha then the possibilities are endless,

walking, tank steering, no prop walk (or very little) in astern

regarding power if the prop size is the same as for the single then it should be double the thrust if you use the same battery for both  run times are half or less that of the single prop, + battery combo. IMHO

R,

[colin-d]

as catengineman says, the possibilities are endless, also as roycv says, a displacement hull has a top speed, and should not be over powered as the ship would become unstable.

not all motors, propshafts  and props are 100% identical

one thing though: the propshafts, cuplings and motors, have to be lined up the same! normally hard to do!
for example at low rpm's one motor could be turning and the other does not.
thats why i use an amp meter and a max of 2volts while installing each rig

but in answer to your question it would or should increase a little of both, if the battery stays the same then your time on the water will be shortend, its not the voltage that depicts your driving time, its the amps..

but if your talking about fast boats, I'm the wrong person to ask   

[maninthestreet]

Ah ha then the possibilities are endless,

walking, tank steering, no prop walk (or very little) in astern

regarding power if the prop size is the same as for the single then it should be double the thrust if you use the same battery for both  run times are half or less that of the single prop, + battery combo. IMHO

R,

What is 'walking' in this context??

[catengineman]

Driving the boat sideways

one prop forward one prop astern full rudder (basic idea)

to do it you will need practice and the astern prop is slightly faster than that of the forward one if you use full port helm then it is port motor ahead stbd motor astern. (dont need a bow thrust)

on a single prop vessel the term walk relates to the effect the prop rotation has on the stern of the vessel

R,