A very good article on endurance (“Less Power for More Range,” March 2016). I have not flown with an engine for many years. But I am an active, current and employed glider instructor.
It seems to me that power pilots seeking best endurance should avoid using an autopilot. I understand that autopilots operate elevators rather than the throttle. I’ve often wondered why one might slow their plane in sink, using up elevator, and spend more time there. Conversely, speeding up in rising air with pitch down, minimizing their time in lift. Endurance to me means keeping as much total energy (potential and kinetic) as possible.
Is this something useful to consider or are new autopilots switching over to throttle control for maintaining altitude?
Franklin F. Mackenzie
Thanks for the kind words. We tried to focus that article on powered airplanes and intentionally avoided getting into the kinds of tricks glider pilots use to maximize endurance.
Typical general aviation autopilots do not manipulate the engine controls—that’s still something the pilot must do. An autopilot that controls the airplane’s pitch usually does so through the trim tab.
I enjoy and value your magazine, and I usually understand most of your content. But I was completely flummoxed by your use of the word “gouge” as shorthand for a clever saying.
After consulting several dictionaries, I was still at a loss for what it meant. I then researched the Internet and discovered its long-time use in the military (particularly the Navy), not for “clever sayings” but for prepared answers to rote exam or interview questions. Your readers might enjoy an expanded explanation of the use of the noun in this context.
Also, I have found your “rule of three” to be helpful in planning descents. I plan on covering three miles for every thousand feet of descent from cruise altitude (in a pressurized King Air).
CFIT and VNAV
In Robert Wright’s article on CFIT (“Managing CFIT’s Risk,” November 2015), one cause not covered—which is unprovable but seems obvious—is the use of Garmin navigators with a VNAV function. The settings offer the option of agl or msl when setting the altitude for the desired waypoint, be it VOR or airport.
Unfortunately, the default option for is msl. If it was agl, there would be fewer CFIT accidents when using this function to descend to target. As it is, if you are flying into a medium-to-high-altitude airport and have failed to notice the default setting, the device will take you into terrain rather quickly. This is somewhat easy to do if the pilot sets the destination airport VNAV to agl and during flight, changes anything such as descent rate, sets an intermediate waypoint and then returns to the destination airport, etc., as the software then automatically reverts to msl for the destination airport.
I lost a good friend and excellent, high-time pilot to this feature at Livermore Airport about 12 years ago. He had just installed a Garmin 530 and was explaining to me how great this VNAV feature was for a controlled descent from a high altitude without doing the math. A few weeks later he and his wife died on approach to KLVK on a moonless night.
Santa Barbara, Calif.
Trimming For The Flare
Regarding the article “Going Around” in January’s issue, I would like to share with you a perspective different from your statement, “Definitely don’t do what some pilots do: using some additional nose-up trim to help in the flare.”
Let’s agree on a couple of aerodynamic concepts:
1. For every airspeed, there is one and only one trim setting.
2. During the flare, as the aircraft is slowing down for touchdown, increasing back pressure is required to maintain a constant nose-up pitch attitude.
For good landings, pilots need to have what I call a fine pitch control—not too much, not too little back pressure. What is right is up to pilot/airplane combination.
Let’s say one is flying a Cessna 182 trimmed for 85 KIAS on final approach. As it slows for touchdown at, say, 60 KIAS, the plane will be out of trim and back pressure will be substantial. Usually this results in a hard landing due the pilot’s inability to fine tune the ever-increasing back pressure. Worse case is a bent firewall.
As soon as the main wheels touch, the natural reflex is to relax the back pressure and the nose gear hits the runway hard. Try to land an Aztec without trim up—a firm arrival is guaranteed. Same with a Cessna 206. In a Cessna 152, it’s not a big deal, either, but of course the 152 can be flown all day out-of-trim.
There is another issue, when the back pressure during the flare is too much, the natural tendency is to put both hands on the yoke—the “two-handed landing.” I prefer the pilot to have one hand on the yoke and the other hand on the throttle.
I like to teach putting some nose-up trim in short final. This will require some forward pressure, but just for a few seconds. I have taught this and it has been surprising how all of a sudden a pilot improves the smoothness of the touchdowns.
If, on the other hand, King Kong or Queen Kong is flying the airplane, he or she does not even need trim—it is a superfluous control. Brute force is all what is needed to tame the beast.
Luca F. Bencini-Tibo
Thanks, Luca. That article noted, “Definitely don’t do what some pilots do: using some additional nose-up trim to help in the flare. If you over-trim the airplane to a nose-up configuration, and must push on the pitch control to maintain the desired speed on final, you’re doing it wrong.”
Our concern with trim in a go-around is the inevitable pitch up when full power is applied in a conventional airplane. As noted in Tom Turner’s article on trim principles, which begins on page 4 of this issue, “If you don’t push, hard, against the nose-up trim, the angle of attack may become critical, and the airplane may stall.” The graphic on page 7 highlights our concern with using too much trim on final, and that of the NTSB.
Your March cover makes me chuckle every time I look at it. It reminds me of the time my husband couldn’t resist showing off and descended rapidly into a steep and twisty canyon, which he followed down to its outlet at the ocean. The passenger responded by covering the entire back seat and floor with half-digested bison burger and fries!
Hidden Springs, Idaho