Constant speed prop question
I just changed the prop on my glastar from a fixed pitch sensenich prop pitched more on the climb side for a hartzell constant speed prop. I have an io320b1a 160hp. My question surrounds the climb performance. While I have a minor adjustment to make on the governor to up the toms from 2610 to hit 2700, the climb performance of my plane is way down. I regularly saw 9-1400 fpm and now the most I can manage is 5-600fpm. The cruise is improved but I could have improved the cruise and sacrificed the climb by have my fixed pitch changed for a cruise pitch. Could that 90rpm adjustment make that much difference? What am I missing, this is really disappointing.Todd
Things I don't think it is
1. Weight. C'mon - 40 pounds makes that much difference? I don't think so.
2. CG - yes, with more weight on the nose there must be more downforce on the elevators, but that sounds insufficient to account for the difference. Gut check, no math.
Let's look at the reported data:
Improved cruise, worse climb. If a CS prop does that when compared to a FP, you have to look at the area and CL of the blades. However, a CS should be able to adjust enough to overcome that. So, is anyone looking at the governor itself?
I took my "transition training" in an RV-6 with CS prop. The takeoffs were dramatic. My 7A with FP prop set up for cruise has a decent climb rate - around 1500 fpm, but that's at least 500 and maybe 1000 fpm less than the -6 on the same 180 HP. These reported results are the exact opposite of what anyone would expect.
And I do agree that you have to compare performance on a similar day. Hot air can make a huge difference. That said, the hot air won't make the cruise any better.