Two or three bladed prop?

[Timmychanga]

I'm designing a P-40, the same wingspan and power setup as the Mighty Mini Mustang (20 inch wingspan, power pack F), But I'm not sure if I should use a two or three bladed propeller. I know the real P-40 has a three-balded prop, but does it really matter at such a small scale?

 

[cranialrectosis]

Love the moniker!

3 bladed props are less efficient but provide more thrust.

2 bladed props provide less thrust but are easier on your power plant and give you longer flight times.

3 blades push your electronics harder. Be sure you can handle them. If going to 3 blades causes your ESC or motor to get hot, use 2 blades.

Welcome to the FliteTest forums!

Got any photos of your P40?

 

[Timmychanga]

So outside of making it look scale on the ground, a 3-blade only makes it go faster? Also, Is thrust angle necessary? I don't have any pictures yet, because The plane it still in the plans stage. But I will post some pictures (maybe an article) once I start construction.

 

[cranialrectosis]

The smaller the plane the more thrust angle will play a part. For a 20" wingspan on a torquey motor I would think thrust angle would be critical to performance.

On a quadcopter 3 bladed props have a more profound impact because the props are the flight surfaces. On a fixed wing, I think, the impact is less.

 

[cvdmaverick]

Just note that typically if you add another blade to your prop you step down by an inch. For example if your motor typically uses a 2 blade 7in prop if you wanted to use a 3 blade you would want to look for a 6in.

 

[Timmychanga]

Got it. If I copied the thrust angle from the Mighty Mini Mustang, do you think that would be about right?

 

[SP0NZ]

That would be a really good place to start. You may have to dial in more or less from there.

Got it. If I copied the thrust angle from the Mighty Mini Mustang, do you think that would be about right?

 

[Timmychanga]

Where would be the best place to post a build log of my p-40?

 

[cvdmaverick]

Where would be the best place to post a build log of my p-40?

The Mad Scratch Builders Corner!

Also, I fly my 60% FT spitfire using the thrust angle provided with the Mighty Mini pod and it flies great!

 

[Timmychanga]

All right. I'll link to the new thread when I start it.

 

[cvdmaverick]

All right. I'll link to the new thread when I start it.

Can't wait to see it!

 

[Timmychanga]

Here is the build log thread http://forum.flitetest.com/showthread.php?36018-Curtiss-P-40b-Warhawk&p=358400#post358400