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[Springboard]

Building my first Springer, got the Spec. but need guidance with prop pitch please. Using  MFA 500 Rocket with integral gearbox on six volts. All from come-in-handy box.  Know prop diameter required but can someone  advise prop pitch please, two or three  bladed. Will not be playing polo brain is too old to keep up.

[hollowhornbear]

just a 35mm three blade scale prop standard on mine.

[Timo2]

Hi

   My unit is   MFA 540motor  with Gearbox 2.5/1   on 6v ,

     38mm 3 blade is good  but  40mm 4 blade is great loads of power  

 Timo2

[CGAux26]

I have been in this hobby only a short time, after a lifetime in full size pleasure boats.  I am still amazed (frustrated)    at the lack of information on the pitch of model boat props.  Diameter X pitch are the two most critical numbers in sizing a prop.  Are there any sources to help this mess?

[dreadnought72]

I think (and I'm more than aware of your frustrations - you're not the only one wondering about the science in all this!) that most model props lean towards a 45 degree pitch.

Andy

[Timo2]

Hi

    1 Link       http://www.raboesch.com


     Timo2

[CGAux26]

DREADNOUGHT 2, I was brought up knowing that pitch was measured as the ideal distance a prop would advance in one revolution.  Thus a prop with 18" pitch will move forward 18" in one turn, ignoring slip.  You speak in terms of blade angle; is that more common on your side of the pond?

And TIMO2, thanks for the Raboesch website.  It appears most of their model props have about the same diameter as pitch.  Not so in big boat props; you can get maybe 6 inches difference in pitch for a given diameter on one style of prop from a give manufacturer (pleasure boat sizes).

[chrise]

Then there is the question of number of blades v blade size v prop design.

There are many designs of prop out there which despite common diameter & pitch might well generate vastly different thrust. There is also no simple link between number of blades & thrust where say a 4 blade prop might well have 4 smaller blades than the 3 of a similar diameter/pitch 3 blade prop from the same manufacturer and the same design range.

Then there is the slight problem of different manufacturers. A flat blade will perform very differently to a airfoil shaped blade of the same size/pitch.

I too would love good comparison data but I cannot find any. I fly electric & if the lack of info was duplicated there I doubt that most fliers would have much success. Fortunately unless you are racing it doesn't matter as much with model boats.

For something that is meant to be simple, like a Springer, & where the last bit of efficiency really doesn't matter much it is a good trouble free idea to do much the same as everyone else.