Comments on: The Pitch/Power Debate: It’s the Trim, Stupid

By: Ron

Ron — Fri, 04 Sep 2009 00:41:35 +0000

Interesting. I’ve never noticed that! You learn something new every day eh?

By: Daniel

Daniel — Thu, 03 Sep 2009 17:06:47 +0000

What makes the problem even more interesting is that in a Cessna 172, when you pull the throttle back, the airplane will stabilize at a HIGHER airspeed than it was trimmed for. I believe the reason is that Cessna mounts its engines with the nose pointed slightly up, so engine thrust is slightly off-axis.

By: ian

ian — Mon, 22 Jun 2009 10:20:31 +0000

well thanks for educating me as an avid 17 yr flight enthusiast. my yr 12 engineering teacher taught me that there were 2 common theories adopted for the principle of flight. Bernoulli’s and the down wash principle but that textbooks adopted the Bernoulli’s concept. thanks to cedarfever for teaching me that they are both valid theries

By: Byron

Byron — Mon, 29 Sep 2008 02:41:57 +0000

Ron makes a few excellent points. from my instructing days, one lesson taught prior to instrument training was that any aircraft can be flown at any airspeed, at any pitch, at any power setting and still be in stable flight. I currently fly the Boing 757 and 767. If you don’t trim the aircraft you will get tired very fast, even as light as the controls are. It is common to see trim changes from level flight to landing of around 40 to 60 percent of the entire range of motion. As for the pitch/power debate, the key is knowing when to use one or the other. Newer models of the 737-8/900 and the 767-400 are much longer than earlier models. Upon landing if you attempt to pitch to control rate of descent for touchdown instead of applying a little power you will more than likely have a tail strike. Not very common for private through commercial students to have this problem. But the awareness can be taught. Not all airplanes land well at flight idle. show your students how to land with a little power and at idle. they will see what that does to pitch over the runway. It will be more pronounced.

By: CedarFever

CedarFever — Sun, 28 Sep 2008 19:12:25 +0000

It’s funny how certain bits of aviation ‘common knowledge’ can be so wrong – “dogmatic” almost doesn’t do it justice sometimes. I had someone once insist to me that symmetrical airfoils DO NOT CREATE LIFT. That was a fun conversation. In the R/C world, it’s the same way. I try to drill into my students’ heads the lessons I’ve learned from full scale and it’s always fun to see the light bulb click on when someone finally understands.

Another good one that tends to divide pilots into “less filling/tastes great” camps is to ask if it is the low pressure on the top of a wing or its downwash that creates lift. HA! Trick question – both do. A stalled wing still produces some lift – just not enough to maintain altitude. Just as with the power/pitch relationship, it’s a combination of both that create the effect and it varies from airframe to airframe and with differing ambient conditions.