Spinner Size and Prop Performance

[Zahnarzt]

I have had very good success with the Suppo BL-2217/7 motor/APC 6x5SF prop combo recommended as a "high performance" option to power my FT warbirds. I love the Spitfire and the Mustang and have build a few of each already. I currently use a 2 1/4" Dubro spinner on this power combo on all the models, but it looks like the 2 1/2" version looks better. The 2 1/2" spinner really seems to cover up a more prop. Would performance be significantly affected with a 2 1/2" vs. 2 1/4" on setups like this?

Thanks in advance.

Z

 

[quorneng]

The best way to look at it is about 2/3 of the thrust comes from the outer 1/3 of the prop blade so the loss from increasing the spinner diameter is relatively small and in any case may be made up by the better streamlining the spinner gives to the fuselage.