Hi all.

 

How / when am I supposed to use the prop pitch?

 

I kind of understand that pulling the blue prop pitch lever out increases pitch of the prop and therefore slows the prop RPM down, this should also result in a bigger "bite" of air that the prop gets thus resulting in a higher speed, am I correct in this assumption? Because when I do this the plane acutally slows down.

 

Also, are we supposed to decrease manifold pressure / power first, before we decrease (push in) prop pitch, to avoid over revving the enging / prop I keep getting confused about this.

The rule I use is "prop on top", meaning that if you are decreasing your power settings, reduce MP first, then prop, and the reverse order when increasing power settings.

 

The FSX learning center, under Lessons->Commercial Pilot, has a lesson called "Complex Aircraft Checkout" which goes into a lot of detail. Carenado provided performance tables with suggested RPM and MP settings for different cruise altitude/temperatures, depending on what speed and fuel flow (Gallons per hour) you want. On the PFD there is a Lean Assist function that is very handy to get the best performance.

 

What I usually do is take off at max RPM and pitch for Vx to around 500 feet, then reduce MP/RPM to 25/2400 and pitch for Vy until well clear of terrain, then reduce pitch further to around 100kt. See also the normal procedures and reference doc that came with the aircraft. You can leave it at 25/2400 all the way to cruise altitude.

Thanks for the reply mate, that was actually helpfull, I'm off to do some reading.

What I do is climb out of pattern altitude with prop max and throttle max.

 

Changing MP first is absolutely correct. You throttle back for climb, then pitch for climb. I use 25 squared (25 MP, 25 RPM) for climb in the R172K Hawk XP. As you climb, note MP decreases so you may have to increase the throttle to maintain 25 in/HG. I cruise at 23 or 24 squared, though at higher altitudes you can't get that MP with the throttle full forward.

 

Having a CS prop is nice because of the fuel savings and performance you get. You get good climb performance as with planes that have a climb prop installed. But you also get good cruise performance, as with planes that have the cruise prop installed.

 

Feel free to ask me any questions any time.

Changing MP first is just a safe side. At most (normal aspirated) engines, it's unlikely to damage engine by operating prop first. As long as you do not go into extremes, it really doesn't matter which lever you move first.

The best primer on the subject of C/S prop engine management was a series of articles written by John Deakin over on AvWeb.

 

http://www.avweb.com/news/columns/182081-1.html

http://www.avweb.com/news/columns/182082-1.html

http://www.avweb.com/news/columns/182084-1.html

http://www.avweb.com/news/columns/182085-1.html

 

Thanks all, this is very informative, I appreaciate the replies.

 

Rgds

Jason