Props..shuckin' and jivin'
I've been pretty happy with the way the YS .63 has been flying the Sledge with the 13X5 Zinger. Real happy. But it seemed like it would burble a little right in the hover zone..and for a neophyte hoverer like me it was kinda tricky. One of the 3D masters at Houston even mentioned how it had a little catch "right there" but the engine was brand new then and I wasn't too concerned.
So I got some 14X4 Zingers and did a little work on one..sharpened the LE and TE, thinned the airfoil, thinned the tips, swept the tips, left the back alone. These tricks I've picked up here. Well it worked great...turns about 600 more than the stock 14X4, about 400 less than the stock 13X5 I've been running.
But while I was trying it out in the back yard I noticed something...right in the 1/4 ~ 1/3 stick throttle range, the throttle servo was going nuts. This was causing the burble...it wasn't really a burble, but quickly fluctuating throttle settings... I guess a vibration right at that RPM was making the pot wiper jump. Worked smooth at Idle and WOT...the only two settings I usually mess with while running one up. It was a HS-81. I've got a lot of these on throttles and this is the first one that did that, it was new when I built the Sledge.
So I swapped it out...throttle works great again. When I was building this plane I accidently left out one of the center ribs, and the throttle servo is mounted in the center rib. I ran a couple of 1/16" balsa sticks up eack end of the servo cut out, made it stiffer, and I think this must have helped. Too much trouble to only change one thing at a time in true troubleshooting fashion, so it could have been the servo, the mount, or both.
So on to the field..man this re-worked 14X4 wood is sweetness. I only got one flight in after all the servo changing time, but I can do knife edge loops at a lot less throttle, knife edge in general is better. This thing will do some high alpha knife edge!! And the engine sounds great through the entire throttle range. That alone was worth the bother.
And I might not have noticed if not for fooling around with different props.