I have a Super Sportster that calls for a 2 1/2" spinner but all I have is a 2 1/4". It fits the motor and recommended prop size fine with room to spare. Will the 1/4" difference be all that significant? Don't want to buy if I don't have to.

Not on a Super Sportster it won't. Go ahead and use it

Since the Super Sportster is an open cowled plane the smaller spinner won't even be noticed. go ahead and use it.

Ken

You may have to reduce the size of the cowl ring if you want the cowl to really blend with the spinner. You could also leave it as-is, you may not notice the 1/8" difference.

Speaking of Super Sportsters, Ithink I need another one. May hve to put one together.

Spinner size is all about what looks best (to you) on the plane, simple as that.

Oops, forgot you have a cowl on this plane. But it's no big deal. you'll just have to carve the cowl to fit the new spinner. it will still work

Ken

This is not true in many cases. In most planes with cowls the spinner is sized to fit to the cowl, and changing the spinner size will break the lines of the cowl and make the plane look "odd". In this case it doesn't matter because he is building the cowl for the plane and will be carving the cowl to fit the spinner.

Ken

Idon't understand the difference between making the plane look 'odd' and the plane not looking right to you...

There are many things that may make the plane not look right to yourself, for whatever reason. But there are ways a plane is "supposed"to look, and this is what Iam addressing. If the spinner doesn't match the cowl it's fitted on it makes the plane look add as that's not supposed to look like this.

Ken

shd3920, have you mounted the engine and started to build & carve the cowl yet? I've always though these would look really cool if the engine were side mounted like on the Ultra Sport. The cowl might look really good that way, especially from the side.

The engine is mounted but have not started the cowl yet.

in some cases particularly when your talking about scale planes the spinner size makes a big difference in the overall look of a plane, warbirds in particular look funny when the lines are not smooth in transition from the edge of the spinner to the cowl front, it looks odd when the lines are broken up and the spinnertakes away from the looks of the aircraft, rather thancomplement the lines of the plane.
what wouldthe full scale plane use, when fitting a spinner, a small amount like a 1/4" is not a big change in the lines of a super sportster, but can make a scale plane look off enough so that there is something out of sorts,its a matter of choice on what your plane looks like.