Why are we taught to pitch up out of free level in low ground effect energy well before any obstruction? Why are we using the airspeed indicator to manage performance rather than simply using the obstruction itself to manage maximum performance? Does pitching up out of ground effect and leaving a thousand feet or so of runway low ground effect energy unused make good energy management sense? Math wise, energy wise, law of the roller coaster wise, airspeed is altitude and vise versa wise, a couple hundred feet over the obstruction is the same energy potential as cruise airspeed in low ground effect near the obstruction. What are the advantages of airspeed over altitude at this juncture? Does a couple hundred feet of altitude here give us more options and greater glide distance without power than cruise airspeed here? Which allows safe maneuverability, both horizontal and vertical, here?

Vx pitch attitude is appropriate at the point where Vy pitch attitude will no longer clear the obstruction. Vy pitch attitude is appropriate at the point where DMMS pitch attitude will no longer clear the obstruction. But what is the most efficient indicator of the most airspeed over the obstruction? Simply staying level in low ground effect is the way to attain and be sure of the greatest airspeed over the obstruction or beyond the airport. Staying down in low ground effect is the only guarantee of zoom reserve maneuverability once out of ground effect. Zoom reserve airspeed is enough airspeed to safely maneuver horizontally or vertically or both.

Doing the math is fine. Managing all available energy to get the safest outcome is finer. Vx or Vy is not safe unless required to miss the obstruction. How many times could a pilot be startled at too low an altitude for recovery from stall? I can attest to several. I am alive today simply because I always managed to have zoom reserve airspeed until slow and ready to squat.

Sometimes neither are appropriate. I was pitching to 100 mph right after getting off the water with floats to help keep my CHT'S down. I recently had a ATP pilot in front of the cub, went out to do some slow flight and I said go to 3,000 AGL. I noticed we got up to altitude fast then the light went on. He never looked at the CHT temps, just stuck it at VY and climbed. Damm turban jocks! Lots of stuff they don't teach like how to take care of a piston engine!!
DENNY

A long time ago when I flew lots of 65-85 hp tired Continental powered airplanes midday in summer, I would descend from 500' to ground effect in the desert to cool the engine. No CHT but oil temps would run 220, especially with faster turning 85 hp. Finding orographic or thermal lift to get up to cooler air helped as well. Trying to climb in downdraft air rather than managing ups and downs also would heat an engine. Air is thinner than water, but it is still good energy management to go with the flow (up/down as well as fore/aft.)

Awwww commmme onnn DENNY those turbans get hot too…….when the super computer fails to work….or it’s on fire. Besides that ATP pilot in front of the cub probably switched its FMC power selection from ECON to BEST RATE.

TVATIVAK71 wrote:Awwww commmme onnn DENNY those turbans get hot too…….when the super computer fails to work….or it’s on fire. Besides that ATP pilot in front of the cub probably switched its FMC power selection from ECON to BEST RATE.

Wait, I thought turbans were on fire any time they’re running……hence the term: “Let’s light the fire”…….

MTV

With the fast airplanes, making the intake bigger for more ram air seems useful and cool. Making a bigger fire in back to get a bigger suction is how helicopter and turboprops (not so much ram air) work, but the metal in the hot end will only take so much. Starting is a problem because the fire is not getting out the back as well, but we are not fan jets. It's like geometry. I understand the explanation, but can never come up with how it works on my own.

Acceleration in low ground effect is much easier to understand.

My pilot mind likes black and white. The concept of using ground effect to better clear obstacles seems pretty gray. That’s where I get stuck. VY or VX are relatively black and white, calculable, hard numbers. I can’t think of a really good way to learn the site picture and relate it to the airplanes performance in ground effect and then climbing to clear.
I totally get the free energy of ground effect, I just can’t really figure out how to learn to use it.
I’m open to ideas and I do like what you write, Jim. It’s hard to parse through sometimes but it keeps me thinking about flying and I thank you for that!

flyingzebra wrote:My pilot mind likes black and white. The concept of using ground effect to better clear obstacles seems pretty gray. That’s where I get stuck. VY or VX are relatively black and white, calculable, hard numbers. I can’t think of a really good way to learn the site picture and relate it to the airplanes performance in ground effect and then climbing to clear.
I totally get the free energy of ground effect, I just can’t really figure out how to learn to use it.
I’m open to ideas and I do like what you write, Jim. It’s hard to parse through sometimes but it keeps me thinking about flying and I thank you for that!

Ummmm, both Vx and Vy vary significantly with weight AND density altitude. In fact at an aircrafts service ceiling, Vx and Vy are the same.

So, they are NOT “hard numbers”. Not even close.

MTV

The simplicity of low ground effect is that the longer we stay there the faster we go, up to maximum possible airspeed. Mike, do manufacturers still get top airspeed for their POH that way? The variability of Vx or Vy is what Mike said and airspeed indicator variance, greater gust spread influence up there, nearness to stall airspeed, updraft and downdraft issues greater than in six inch ground effect, etc. etc. etc., and farther to fall. Did I say farther to fall?

The Vx or Vy takeoff (no zoom reserve airspeed) fall from a few hundred feet seems to be the more common fatality around the airport. Just ending the training indoctrination that the Vy (best rate of climb) is the safest pitch attitude would help I think. Not having had that indoctrination and not orienting myself that way has saved my life I don't know how many times. Does it take a math imbecile like me to be a safe pilot? I could use a whis wheel and get the estimate for those IFR reporting points before distance measuring, but I still didn't believe that an airplane would necessarily climb at Vy. I think somebody just did the math and didn't fly or care to fly. The airplane certainly doesn't like Vx or Vy as appropriate. Yes, I have had the need for actual Vy as appropriate and couldn't get it. I hit a fence rather than stall the airplane. But I have stayed alive a long time using low ground effect to get zoom reserve before maneuver or climb. Yes, it was mostly maneuver in the kind of work I did.

I understand most pilots have to get up to altitude. Just don't kill yourself trying to get there quickly for safety. Vy is not generally the safe way to do it. Vy is way overrated in aviation.