Let's Make Robots!


GM3/GM9 strength at low voltage?

I need help from someone who owns a solarbotics geared motor type GM3 or GM9, or even better: both!

I wantot to know how strong they are when driven directly from a single AAA 1,5 Volt battery. If you hook it up to the battery and hold on to the axle/output shaft, will the motor be able to spin itself around? Would it be able to keep spinning if you taped the battery onto the motor body, or would the added weight of the battery be to much to keep whole contraption rotating around its own axle?

Windshield wiper motors, have you tried'em?

Have any of you experimented with windshield wiper motors? I know they've been used in budget robotwars fighters. I just need to get an idea what kind of strength they have (with the original gearbox).
Will it be able to pull 20 Kg vwith a 20 cm diameter wheel mounted directly to the output shaft? what abot 50 Kg? -or a 100?

how to calculate motor strength?

Is there a common formula for finding required motor strength?

If I know the total bot weight and wheel diameter, could I find out what kind of motor I need. I know that gearing will come into play, but I dont know anything about these physics thingys so I choose to phrase the question as vaguely as possible.. 

Like, what kind of specs would a motor for a scooter (with me on top of it), doing 35km/Hrs require

or,  an offroader weighting 10K, doing 3km/Hrs with 10cm big wheels in rough terrain?

GM10 motor strength

I've ordered th GM10 geared minimotor from solarbotics.

link: http://www.solarbotics.com/products/gm10/

I know some of you have used it before.

Mine haven't arrived yet, so I'm still dreaming about it.

Here's a quick question for those who know it;

How big a wheel can I connect directly to the output shaft on the GM10 without any significant loss of power. I see they ship it with an optional 25mm wheel, is that the biggest recommended diameter, or can I go bigger without gearing it down further?