3 Blade prop size?

[Winco Steve]

Hi all,

Just getting things together (still!) for building up 'The World Models' Tucano 60       ( W/Span 63 ins, Wing Area 627.8 sq.ins, Flying weight 7.4 lbs, Fuselage length 54 ins)

Power will be via Irvine 61 (two stroke) and, as the original has a 3 blade prop, that is what I need advice on! I'm thinking of a 10 x 7 Master Airscrew or maybe a slightly larger 11 x 7. Any advice? Never used a 3 blade set up before. I appreciate the pros and cons of 2 versus 3 blade but would like to get the model to look as realistic as possible.

Thanks all,

Winco Steve

Edited By Winco Steve on 08/09/2013 10:53:43

[John Privett]

Usual advice, Steve, is to go down an inch on the diameter compared to what you'd have used as a 2-blade prop.

[Winco Steve]

Hi John,

Yes, pretty much what I have done ( worked on a 2 blade at 11 x 7 therefore 10 x 7 3 blade). However, I am not 100% sure of suitable prop. size ( 2 blade ) for this particular model as the instructions are silent on this issue.

Thanks,

Winco Steve

[Former Member]

[This posting has been removed]

[Ian Jones]

The reason for using three (or more) blades is normally to acheive ground clearance that would not be available if a 2 blade prop for that particular engine was used.

So yep stick to 2 blades if you can but I have used three bladed props okay - you would really only notice the difference if the available thrust was marginial in the first place.

I agree getting spinners can be a pain.

Ian

[Winco Steve]

Hi Guy's,

Thanks for the advice. I just wanted to keep the model as close as possible to scale. If using a 3 blade prop. is just not worth the hassle then I have a box full of 2 blades and spinners to match!

Regards,

Winco Steve

[PatMc]

A 3 blade wouldn't be more scale than a 2 blade anyway, the full size use 4 blades.

[Winco Steve]

Hi PatMc,

Well, not quite correct I'm afraid! Having trawled the Internet and reference books I have come across variants with 3,4 and even 5 bladed props ( the Brazilian 'smoke squadron' planes being shown with both 3 and 5 bladed which is the model I have). One variant, used by the R.A.F. as a trainer, is clearly using a 3 blade prop. I have just done another search and actually found one with a 2 blade prop (bit of a rarity I think) ! So, pretty much covered all way!

Thanks for your input, much appreciated.

Regards,

Winco Steve

Edited By Winco Steve on 09/09/2013 20:17:23

[Panther1]

I use a 3 blade on my little PC9 and it looks great and performs really well. What more do you want? I found that the last couple of times I bought Master Airscrew props, the manufacturer has guidelines on the packaging for upgrading to a 3 blade prop. From memory it was drop down 1" and up 1" in pitch from a 2 blade. As the prop size increases this rule changes. I found it doesn't matter too much with a model as I had a spare 3 blade with less pitch and the model really sizzles. It is also far less load on the motor and I get good long motor runs and that outweighs any extra performance thay may be perceived by more pitch.