Hartzell Composite Neutral Thrust RPM?

[BillL]

Does anyone know what the neutral thrust RPM is for the Hartzell composite blades? I was just (over) thinking about rpm and thrust at, say, 70 mph. If the prop governor is set to full speed, and the rpm is reduced, there is some point at the positive thrust goes neutral then negative.

Is this known or part of the Phase I testing?

[n82rb]

normally around 11 or 12 inches.

bob burns
rv-4 n82rb

[BillL]

Originally Posted by n82rb

normally around 11 or 12 inches.

bob burns
rv-4 n82rb

Thanks Bob, I will give that a try on first flight and see what rpm that is.

I might just drop a note to Les Doud, for a neutral thrust RPM vs airspeed graph.

[David Paule]

Bill, respectfully I suggest that this be postponed to a later flight.

On the first flight, I think it would be better to keep things very simple and spend most of it just assessing only the systems that are most essential for safe flight, and even then only on a go/no-go basis. Things like temperatures, flow rates and basic functioning. Even then you can postpone serious data collection till later.

The main question to answer, is whether the systems and basic handling would permit another flight or whether you should get it back on the ground pronto.

If the answer is yes, it's safe, or better yet, "oh heck yes!" then take a few minutes to soak in the experience.

Then prep for your very first approach and landing and take it back for a thorough inspection.

All my opinion, of course....

Dave

[flyinga]

Just curious, what is the purpose of finding neutral (zero) thrust on a single engine airplane unless you have a full-feathering prop?

[BillL]

Originally Posted by David Paule

Bill, respectfully I suggest that this be postponed to a later flight.

On the first flight, I think it would be better to keep things very simple and spend most of it just assessing only the systems that are most essential for safe flight, and even then only on a go/no-go basis. Things like temperatures, flow rates and basic functioning. Even then you can postpone serious data collection till later.

The main question to answer, is whether the systems and basic handling would permit another flight or whether you should get it back on the ground pronto.

If the answer is yes, it's safe, or better yet, "oh heck yes!" then take a few minutes to soak in the experience.

Then prep for your very first approach and landing and take it back for a thorough inspection.

All my opinion, of course....

Dave

Thanks for the nudge. You are quite correct, first flight is a bad time to experiment like this. More essential and basic things are much higher priority.

Originally Posted by flyinga

Just curious, what is the purpose of finding neutral (zero) thrust on a single engine airplane unless you have a full-feathering prop?

I was taught to slow to ~70kts and descend with RPM at about 1800 (initially) for the CS prop. Since best glide is close to that, I was just wondering what neutral thrust rpm is to better understand whats happening in the landing process. I have the composite hartzell and expect that it will provide quite a bit of drag when rpm drops. Over thinking for sure, but not an unsafe activity for a couch.