Prop Size Comparison - Photo

[dag-nabit]

Since there are so many inquiries here about props I thought I would post a photo of a few different props to help folks visualize the difference between them.

Unfortunately you can't really see the difference in pitch in the photo. Diameter and Pitch is shown under each prop.

Hope some of you will find this helpful.

Kevin

http://i173.photobucket.com/albums/w71/daidavies/RC%20Boats/2e9d4480.jpg

[lenny]

Thanks !!
Still not shore on how the pitch differences work,
like i have 42mm x 55 and what to prop up, or need more pitch for speed.

Thanks for input.

[dag-nabit]

There are many factors to consider, including the shape/size of the individual prop blades, and the ability (power) of your motor to spin a particular size of prop without loosing too much RPM.

Assuming though the design of the props are the same, and your motor will spin them effectively.

This is explanation is rather simplified, and "rule of thumb" so to speak, but it will provide some basics to build on.

Going up in diameter means more prop surface area contacting the water. This will result in better efficiency, or less slippage. You may see a slight increase in speed because of a reduction in slippage, but the real advantage is getting the boat moving, and on plane faster.

Increasing pitch will give you faster speed. If you look at the pitch number, for example 52mm, this means that for every rotation of the prop it will theoretically move ahead 52mm. But that assumes 100% efficiency, which is not possible.

Increasing either diameter or pitch will increase the load on your motor.

So the goal is to find a prop with the right diameter to reduce slippage and the correct pitch to give you the forward speed you want, without overloading the motor.

Sometimes staying with the same diameter but increasing pitch a bit will give you the results you want.

Sometimes, especially if your motor is close to maxed out, you need to reduce diameter a bit and increase pitch to get the best performance. By unloading the motor a bit by reducing diameter, you may gain back some under load RPM. The extra RPM plus the extra pitch can compensate for the efficiency lost by reducing the diameter, and the overall performance will improve.

Other times, if your motor and ESC can handle the load, you can increase both diameter and pitch, and double the bang for your buck.

It is about finding the right balance for your set up.

You can run some calculations to get a ball park idea on what size props to run, but it comes down to trying 2 or 3 or 4 different props to see what works best.

When propping up, always monitor your motor, ESC, and battery temps closely for the first few runs to make sure you aren't over loading the system. If you have the ability to monitor amp draw with a WATTS UP meter, Eagle Tree, or similar system, these are also great tools to evaluate the load on the electronics.

Kevin

[JPriami]

nice work Kevin

[roadrashracing]

The grim racer 3 blade does not work well in stock form, just letting people know.

[JPriami]

The grim racer 3 blade does not work well in stock form, just letting people know.

What batteries were you running?

[JPriami]

And 6S lipo runners with upgraded setups. Watch the X series props like the x445. I tested on out and it seemed to propwalk and the M series doesn't seem to do that as bad.

[roadrashracing]

What batteries were you running?

7 cells, did not get on plane well and just did not run good, it did better with the stock prop