andrewtexas123

What size Spinner will I need for an os65la?

Andrew

Jetdesign

My Feedback: (8)

whatever looks right on the plane. doesn't have much to do with engine size. what plane is it?

Jim Thomerson

In a 1949 Aeromodeller annual there is the statement that the most aerodynamicallly efficient spinner is 1/5 the diameter of the prop.  A 2 inch spinner for a 10 inch prop, for example. 

ppkk

If this is true, then it is a good rule of thumb to know.

Is it common to have to enlarge the spinner's blade openings so that the propeller fits or do you pick the largest spinner that accomodates the propeller withouth having to cut anything?

Jetdesign

My Feedback: (8)

It is common to have to cut. Some manufacturers sell spinners with larger cuts, or even will custom cut a spinner for you. Always try to make your cuts even to avoid throwing things out of balance.

Gray Beard

My Feedback: (-1)

Spinner size depends on the plane itself unless it's an uncowled type, then the rule may or may not be correct??? Ijust haven't heard that one before but it sounds pretty good?
If you have an idea of the prop size you are going to use then you can order the spinner cut for you at TruTurn spinners. They were doing it for free a short while back, Iget mine cut for a bigger pitch then I plan on using so Ican test other props without cutting up my new spinner.

andrewtexas123

Plane will be a Sig Senior Kadet with a 12*7 prop... Let me know what size I need still not 100% sure!

Andrew

Jetdesign

My Feedback: (8)

That plane comes with a 2" plastic spinner in the box.

Try making the profile of a spinner out of a piece of paper and hold it up to the plane to see what it looks like. I did that for my Yak and it worked out really well.

You can to to Tru-Turns website to get dimensions of different shape spinners if you want, or just try to find the diameter and length of the prop and sketch it.

redfox435cat

1/5 the prop length for an open engine sport model. othewise you pick the spinner for the model. Other wise use a 1 inch spinnernut

Gray Beard

My Feedback: (-1)

So Ineed a 5 inch spinner on a 25 inch prop??

richardgerardi

A 2.5 or 2.75 Goldberg spinner should do. This spinner will most likely not be cut since they can accomodate APC props. Good luck

gsoav8r

My Feedback: (6)

^-x2
Fromeverything Ive readover the years it is said that for max aerodynamic efficiency of a prop a spinner may be 1/5 to 1/4 the diameter of the prop. This is because the spinner covers the extreme pitch of the prop near the hub that is most likely producing more drag than thrust.

So having said that, in the real world I match the spinner / prop nutto the plane. IMO the prop efficiency doesnt matter much for typical sport flying.

Cheers.