I'm new to this hobby and would like some clarification on the numbers on the propeller. I know that the first one is the length of the prop and the second is the pitch. But does pitch increase or dcrease with the number increasing. Thank-you

The first number is the length of the prop and the second number is the pitch.

Roughly speaking and without getting all technical.... A prop with a "5"pitch pulls the prop forward 5 inches with every turn and a prop with a "6"pitch pulls the prop forward 6 inches every turn etc, etc.

So a higher pitched prop will fly the plane faster and a lower pitch prop will fly slower, just make sure you stay with a prop in the correct size range for the engine.

The higher the second number the larger the pitch. So a 12x6 is easier to turn than a 12x10.

In many cases using a lower pitch number is like shifting a car into a lower gear. You won't go as fast but you can make a steeper climb (hill).

Since you are just starting out here are some suggestions. For a 40 size engine use a 10" prop with a pitch of 5 or 6. For a 46 engine go to an 11" with a pitch of 5 or 6. For a 61 size engine go to a 12" prop with a pitch of 5 or 6. For the 40 or 46 engines use a Master Airscrew brand. For the 61 engine use an APC brand. Don't go higher than a pitch of 6 in most cases. The extra pitch will load the engine down too much and you will actually lose speed. For all around good performance i like to use a 5 pitch[8D