How much motor does it take?

[Kmot]

I want to spin a 60mm prop on the Atlantic tugboat. I would like to know how much motor it would take to spin it direct drive, and how much motor to spin it with reduction drive of 1.5:1, and 2:1 ratios.

Thanks for your help! :)

[nick_75au]

If it helps, Cols Mariner runs a 700 motor with a 3:1 gearbox and 65 mm prop.

I think you might want deeper gearing than you have for the std can motors. They will spin the prop but want fairly deep reduction to be efficient.

Motors 2500-5000 rpm maximum unloaded for direct drive. Motors that spin in that range will generally be large enough to drive that prop directly ie the American bocsh you have.

The voltage you run at will have some effect as well.

Regards
Nick

[Kmot]

Thanks Nick! I plan on running a 12V SLA.

[Rob_P]

Don't forget to figure in the number of blades and the pitch

[blckgnx]

Hi KMOT,

For what its worth, here's what Harbor Models recomended for my Atlantic power:
Motor: MFA Torpedo 500 w/6:1 gearbox
Prop: Rivabo 4 blade 45mm (pt# 544-46)
Drive line: 4mm drive shaftw/matching stuffing box
Coupler: MFA 4mm x 6mm

I did the same thing your'e doing, and am in the middle of the build now, so I don't have a test of the power yet. Ron
I'll post some pics soon.

[Kmot]

Thanks Ron. Since I have the clearance for a 60mm prop, I am going to use it. I want this thing to pull like a beast. I am going to get a Rivabo 60mm four blade prop. I don't know the pitch because they don't specify it (Harbor Models).

[Hoghappy]

The cheap 550 Bristol motor matched with the 2.5/1 master airscrew box drives my 55mm prop very well...I feel that I could go direct drive with it to get a little more whump out of it if i wanted too...the motor very stays cool.

Capt. Crash

[fgroza]

Kmot,
You can get a inline bolt on gearbox for around $30 that will go on a 500/550 size motor. They come in two different gear ratios and are made of aluminum. Look in the motor section of Hobby Lobby's catalog for it. It's made by MP Jet. They are made for Speed 400 size motors also. Since it is inline, rotation will be the same as the input direction of rotation. I use these on planes with success.
Frank

[Kmot]

Robert, thanks for the info. Those airplane geardrives are nice and they are also inexpensive.

Frank, I have two MP Jet gearboxes mounted on Kyosho Mega motors in my TXT-1 monster truck. I did this conversion about 4 years ago I think.

[Hoghappy]

Tom I forgot to mention I'm running on 6 volts. :rolleyes:
Capt. Crash

[Kmot]

I keep forgetting I have reference books. :rolleyes:

I just finished going through "Scale Model Ship Propulsion" by Tom Gorman and now I know I will for sure be using some sort of reduction.

[Greg Hiltz]

My recommendation would be the Robbe gearmotor, with 5:1 reduction for scale or better speed, with gobs of power, or the same motor with the 3.3:1, for a more speedier tug. These motors are only approx. $50.00, and work very well. I believe, from memory, the Robbe Nos. are 4107 or 4108

-Greg

[Kmot]

Thanks for the info Greg. :)