Sunday, November 8, 2009

Comments on Comments

Flap Switch. Yes, the normal Cessna flap switch has been removed and new switch has been installed. Not only is the location different, but the switch is momentary in both the up and down position, you have to hold it in that position to acctuate the flaps, releasing it stops the flap motor from running. There is also a "flap dump" switch on the yoke. Pressing this button runs the motor to bring the flaps up. The motor only runs when the button it depressed, so you "bump" the flaps up slowly. Advantage? Flaps can be deployed in the pattern with out having to take your hand off of the throttle. A normal pattern in a stock airplane would mean taking your hand off the throttle 3-4 times. Not so with the flap switch right at your fingertips (litterally). This allows you to keep the eyes outside (where they should be) with out having to look inside the cockpit during the landing phase. The flap dump (retract) switch on the yoke allows you to retract the flaps on climb out. Also a very important time to have the eyes outside and the hand on the throttle. The flap indicator system is still the same, but the microswitches with the stock Cessna flap selector are removed. This system was installed under a field approval that was developed by JAARS.

23 Squared and Lean of peak. Yes, we do fly at 23 squared (23 inched manifold pressure (or full throttle if not able to get 23 inches) and 2300 RPM. We shoot for around 65% power. Increasing RPM if MAP drops below 22 inches usually. All climbs are always (and should) be made at full throttle. In cruise we lean to 25-50 lean of peak. The leanest cylinder is about 50 LOP and the "richest" is 25 LOP. Only possible with GAMI injectors or newer Continental "tuned" injectors. As a side note, thank you to GAMI for helping us tune one of our engines to have closer matching EGT spreads on all 6 cylinders. As far as 23 squared goes, the only thing that would be better is wide open throttle (WOT) all the time even at altitudes where this would exceed 23 inches. 65% power could still be maintained by having a lower and quiter RPM setting such as 25 inches 2200 RPM. Still working on getting that one passed. The old habits and old guard die hard. More info at Picture form article #18 by John Deakin, "Mixture Magic" This is very brief as I could go on for hours (days perhaps) about engine opperation. Right Nathan? =)

The View. The view is quite awesome. Its amazing to see the jungle and God's creation from the air.


Kars said...

Hey David, let me know how the WOT discussion goes. Trying to get that one passed at Moody too, some of the younger instructors will let you when you show them the book, some of the ones who have been flying a while won't really go for it although they can't show hard proof that it's bad for the engine.

Steve and Laura said...

I agree with everything you said about engine set up except that Continental has a new SB that says not to fly at 2200 RPM. It's too close to the harmonic frequency where crankshaft fly weights start flying separate from the crankshaft. We don't ever go below 2300 because of that. The lean of peak, full throttle thing works quite well though.

Steve and Laura said...

Pretty cool on the flap handle though. I hadn't seen that before. However, it probably wouldn't work in my 185.