109JB's Kitfox IV rebuild

[jrevens]

Slightly off topic, I have bent up a few ripper shanks farming and never had any luck re bending them back to original, they always bend again in the same spot usually worse than the first time. Is there a special procedure for bending aircraft tubing during a repair to avoid that.

I don’t think so. 4130 N (normalized) is usually cold bent, and the bending process causes it to get a little harder and stiffer in the bend area (“work hardening”). Go slow to help minimize that. Respect minimum bend radius and use a good bender if needed to maintain concentricity when forming a new piece. When trying to straighten a bent piece during a repair, sometimes heat is required. If heated too much and cooled slowly it can become annealed and will have less strength.

[109JB]

So this one finally flew. Two flight on it so far and it is running well. However, I'm not getting enough RPM. I get 5200 rpm at full throttle in level flight. From what I'm reading it really needs to be up around 5600. So, to gain 400 rpm on a 3-blade GSC wood prop, about how much pitch am I going to need to take out?

[avidflyer]

If it was me, I would try one degree and see what it does. This is with a 912, correct? Static rpm of about 5300 is usually a good place to be. JImChuk

[109JB]

Thanks Jim. Yes it is a 80 hp 912UL. I'll take out one degree and see how that goes.