View Single Post
Old 06-15-2017, 08:23 AM
  #2  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,590
Default

It really comes down to trial and error. Personally I hate SF props even though some swear by them.

As you already know .... diameter will give thrust .... pitch will give speed.

Verticals need diameter ..... flicks need pitch.

The balance of both is always a trade off .... but luckily with electric we have an advantage over wet fuel. Electrics can run slower and even stop ....
So that high pitch prop is less problem with electrics.

Example ...

My Zlin with wet fuel needs a 15x4 --- otherwise she just has too much low speed idle pull. The 15 is needed for vertical / hanging .... but 4 to tame the idle grunt and speed.
My electric Zlin runs a 15x10 ..... because I can stop / run slower than the wet fuel but get same manouevres etc.

I always aim for large diameter with reasonable pitch. Because you are using 3s instead of 4s .... you need to have greater diameter and pitch to compensate. I use a really rough and ready formula for this :

S x KV x pitch x diameter .... EF say 4S on the 800kv with 12x6 .... which gives 4 x 800 x 12 x 6 : 230400

Now you are using 3s on that motor .... so we play with numbers to get similar final result.

Let's say we take the 230400 and reduce it down ... 230400 /800 /3 : 96

96 is our prop factor .... and a 12" prop in that would be 8" pitch.

I would suggest a 13x7 for slow speed and control or a 12x8 for general.

Nigel
solentlife is offline  
 
Page generated in 0.04458 seconds with 8 queries