Clueless on the basics, help on rpm, torque in order to pull out a succesful engn school project?

i am building a mini prototype that will travel in land and water with great speed. how much rpm do i need and torque. I have been looking on diff kinds of motor and I am clueless. one motor seems to have a high rpm but diff output with load and no load. i don't understand this. In terms of torque what is the hghest possible torque and power need for my propeller

Even though, I love science I have

never been into building models or

anything that has something to do with

mechanical robotics.

My task is to build a miniature model

that will fit in a 4 and 1/2 inches in

diameter water pipe that will have

great speed. The conditions are as

follows: It must travel from one end

to another at a very high speed

powered by up to 8 AAA batteries,

having the pipes empty, filled, half-

filled with water. I have thought of

theories that will make my model

efficient however I am lacking in

resources in which base model to

choose from. One suggested to look

into tamiya miniature

My advise would be to visit a hobbies store. They have everything you need. Use high performance rechargeable batteries, otherwise you´ll run out of batteries all the time! In any case, it is not a lot of juice. Find out how many amp-hours they can deliver and maximize the discharge with the size of the motor.

RPM will decrease with an increasing torque The more torque the better, of course, but it will be limited by the size of the motor, the power source, and the friction coefficient of the wheels/size of the prop.

Props cannot turn faster than 280 rpm, or so. After that, they start to cavitate.

.