OS 91 FS Surpass II Prop Size

[Nick Holmes 2]

Hi,  have an OS91 FS which I am about to fit in a Showtime 90 4D,  does anyone have any reccomendations on the best prop size,  have you got an OS91 FS and found the perfect prop?  Thanks Nick

[Phil Claridge]

i use a 15by5 apc on my saito 91fs fitted to a harrier works well

[Tim Mackey]

IDEAL PROP 14 X 7

RANGE 13 X 8-11, 14 X 7-9, 15 X 5-7.

3 BLADER 12 X 8, or 13 X 6

[Nick Holmes 2]

Hi Guys,  thanks for the response so far,  have fitted an APC 14x7,  only problem is noise!  can't get it below 86db which is out of limit for flying!  Any ideas,  have tried a 14 x8 which reduced it to aboiut 84db not enough need 80db.  The engine is fitted with the standard OS  silencer.

[Tim Mackey]

oy! you have cross posted this question

here

[Graham King]

I use a Graupner 14x7 on OS91 fitted to an old Ripmax (Balsacraft) Extreme - the heavyweight one not the Lite version.  Mine came in at 81Db with standard exhaust

[Phil Claridge]

15by5 apc funfly prop no noisier than other 4s at our patch

[ken anderson.]

hello nick,

 iv'e been using a 13*6 on my os 91's for10--15 years--try one you'll be impressed--i used to use 14*6 and 15*6--until i seen a ultimate biplane performing with the same engine(91) but using a 13*6.

         ken anderson.