CTSW accident NC

[Ed Cesnalis]

3 hours ago, Jim Meade said:

I try to get to 5200 pretty quickly on take-off, at the expense of a little climb angle, although I like to get high early.

Rotax SL-912-016R1 30 Dec 16 says in 3.1.2: (I'm paraphrasing but not changing meaning)

2.  Take-off at wide-open-throttle should be not less than 5200 RPM

3.  Continuous use of less than 5200 RPM at WOT should be avoided.

I suppose it's all in how one interprets those guidelines.

My interpretation is that is speaking to prop pitch.  Vx and Vy departures are done WOT so the variable is prop pitch not throttle position.

[procharger]

My take off RPM is 4900

[FlyingMonkey]

24 minutes ago, procharger said:

My take off RPM is 4900

Mine's very similar at the start of my takeoff roll, maybe 5050.  My prop is pitched very well, so it sounds to me like you are in the right ballpark for prop pitch (assuming 3-blade Neuform prop), maybe a hair on the coarse side.  I have never talked to anybody who actually gets 5200 until late in the takeoff sequence, and you probably would have to climb pretty shallowly to be at 5200rpm.  I prefer a steeper climb out, basically whatever pitch/rpm combo will give me best climb rate.  The ground is dangerous, and I want to get away from it.

[FlyingMonkey]

18 hours ago, Jim Meade said:

3.  Continuous use of less than 5200 RPM at WOT should be avoided.

I suppose it's all in how one interprets those guidelines.

I don't think you could be at continuous rpm less than 5200 at WOT unless your prop is horribly mis-pitched to the coarse side (as mine was when I first got my CTSW), or if you spent all your time trying to climb to the moon. 

I could be wrong, but I don't think Rotax meant to stay away from rpm below 5200 in all circumstances such as takeoff and normal climbs to altitude.  To me "continuous use" means normal operation over long periods of time (say over 30 minutes or so).  But as you say, that guidance is kind of vague and open to interpretation.