Hi Guys. Hope you are all having a great flying season. I need some help selecting a prop. To start with I am 72. At the present time One of my planes is a Hobbico Kaos.. I built it about ten years ago and it has always flown great. It has an OS 40 FP engine in it. The problem is that I am not comfortable with its speed any more. At the present time I am using a 10/6 prop and Red Max 10% nitro. The plane flies great but it is to fast for me. What would be a good prop to put on the plane to keep it flying great vet slow it down?
Thanks for you help.

If it has good takeoff acceleration, and slows down OK for landing, why not just throttle back for cruise? You'll always have the power reserve if you need it. (I'm 54 and sometimes find things a little too fast myself).

The problem is that it lands to fast also.

Try an 11x5 prop. It will slow it down a bit. Good luck!

You may try an APC 11/3 or and 11/4. You may get a better response if you ask the moderator to move the thread to the "glow engine" forum. Most guys here "swing big lumber" :>)

that model is just plain ol heavy -and you can't fly it slow and close in--- easily -
Being only a few years younger - and having had to get special glasses - I understand exactly what you are talking about .
If you can swing it --trade or somehow get a plane with about 2/3 the wing loading - which will fly slower - and give you more time to watch what is going on.
I am currently building some smaller electric stuff - about the same size as your 40 KAOS but 1/4 the weight
so that will fly aerobatics nicely but in close and slow.
I have been flying models since 1949 and built stuff up to and including models used at the TOC by a few contestants.
So I am not trying to sell you on throwing out your Kaos-- I am just saying you might consider another approach.