If Vy is mathematically the most up for the buck, energy wise, why does it kill more pilots than ground effect to cruise and pitch to just over the obstacle?

I really hoped someone would jump on this, because I frankly don't quite understand it. In other threads, people have tried to explain it to me, but I don't quite get it.

The one big thing I had not thought about, is how much the stall AOA changes with altitude, heat and humidity. I mean, I know it, but for some strange reason I didn't think about it in the context of a climbout! But then again, indicated should not change dramatically? So if it is a hot and humid day, taking off from a strip high up in the mountains, when my ASI is showing 60kts, then true airspeed should be much higher and my AOA is more or less the same as 60kts indicated at sealevel, a cold and dry day? Or?

But what I dont get is that if Vy gets us higher by the end of the runway, compared to accelerating and zoooming, then what is the problem with Vy? (I kind of stay a bit away from Vx until it is absolutely necessary) Is it not true? Will zooming get me higher? Is it because Vy is easier to teach? Or maybe when we get used to just always fly Vy, we are less mentally aware and prepared when something goes wrong? The assumption then is that zooming demands more focus, so when the engine dies, you got your head more in the game?...

But maybe this should be in the theory segment and not in the accident analysis? Or is there a connection here to resent events that I have missed? I think I will stay away from that. Very deep waters for me. Do hope people chime in on the Vy-thing though.

I'll add, airspeed is airspeed. The wing doesn't know if you are at SL or 9000'. That doesn't change. But the wing will generate lift either better or worse, meaning you'll either climb better or worse depending on air density. In a climb, it's all about excess thrust. Same as a twin. If an engine(s) quits, excess thrust will dictate if you can climb but the wing will operate the same on same given airspeed.

Lift and drag curves can be moved around to find what you are looking but the FAA does a good job simplifying Vx, Vy enroute climb speeds and so on. Big jets and certification work can produce all kinds of new terminology and in the end really confuse pilots. That's not the intent, to confuse the pilot. K.I.S.S. is my method of teaching. Good luck,

What is more startling to a human, stall or reduction in zoom reserve (the ability to go up or maneuver temporarily)?

contactflying wrote:What is more startling to a human, stall or reduction in zoom reserve (the ability to go up or maneuver temporarily)?

Bingo!

Flight energy in the form of airspeed is THE magic. Airspeed is gained very efficiently in ground effect.

You don't need to know the equations. Practice building energy in ground effect. Practice exchanging altitude for airspeed while maneuvering, and you will see. If you don't see it, keep practicing and eventually you will develop a feel for energy management.

I can't say that in my three decades of flying, that I have once needed Vx. Maybe I'm doing it wrong...

I dont put too much trust in my ability to do maths while flying, so my goal is to keep doing it until I get a feel for it. But I am trying to wrap my head around it so I can have a feel for whats going on. Dont know if that makes much sense… If for nothing else, then to avoid me forming my own, potentially wrong theory that might get me into trouble later.

Nobody seems to dispute that Vy will get us higher up faster. But it is still just potential energy, and for it to be of any use, we need to nose over immediately. Subtract reaction time, and then add the unknown factor of a startled and maybe panicking pilot trying to turn back, and a stall spin might become an increasingly more likely outcome of climbing out at Vy.

Id go out and practice more, and write less here, but the weather is unusually bad. It has been raining cats, dogs and other assorted pets for a while and does not look like it has any plans to stop soon.

I believe the idea is that the survivability of the loss of an engine on take off goes up the higher you are when it occurs. Vy gets you there over the shortest amount of time and Vx gets you there over the shortest amount of distance (somewhat longer amount of time). I think contacts point is valid that height at the loss of engine event isnt the only factor.

I think the FAA has to make its "rules" for all situations, someone flying a bonanza out of a densely populated city or someone flying a cub off a grass strip in the middle of Kansas. I can see an argument for the cub pilot to fly in ground effect to cruise and I can see an argument for Vy with the bonanza pilot in the city.

I see your point Josef. The Bonanza is going to generate more inertia, I guess, so would have more energy from Vy airspeed at engine out to Vy pitch attitude at remaining speed after some seconds reaction time or startle time. Still playing with fire, I would think. The Cub will maneuver better because it has a much slower stall airspeed. The Bonanza, maneuvering less well, may need that extra energy to be able to put the cabin between a couple of houses rather than into one. Altitude is time. How big did you say that town was? Altitude is time that can be traded for airspeed for safer maneuvering. Dumping the nose, so important as both stall prevention and stall recovery, is the obvious school solution if already up. Already up is high altitude orientation. My orientation is totally different. Energy management, developing and keeping rather than recovering kinetic energy or airspeed is low altitude orientation. Leaning regardless of DA is sucking up every drop of kinetic energy. Tail up soon or nose wheel just off soon is sucking up every drop of kinetic energy. Mains off well below Vso when the wing will fly in low ground effect is sucking up every drop of kinetic energy. Staying level in low ground effect as long as runway or desert is still ahead is sucking up every drop of kinetic energy. Pitching up only when forced by obstructions that cannot be rudder turned around wings level is sucking up every drop of kinetic energy. Down drainage egress is sucking up every drop of kinetic energy. Trading even a little altitude for enough airspeed to continue flying is sucking up every drop of kinetic energy.

Do we need all that kinetic energy every time? No. Do we need to at least consider using every bit of that free kinetic energy available that we are comfortable with? Yes. In a Bonanza? Yes, certainly if we need it. Stall is game over.

The basic low ground effect takeoff can decelerate to Vy airspeed by trading zoom reserve airspeed for altitude, still at full power. Once we pitch up out of ground effect, however, pitching back down later to trade altitude for airspeed will never recover the ground effect energy rejected. Unused ground effect over thousands of feet of remaining runway, unrealized safe cruise climb airspeed, is energy management mismanagement. Even IMC takeoff, pitching to one bar width on the AH, trades less airspeed for altitude than does Vy pitch attitude. And IMC takeoff is along a safe and legal procedural track. VFR takeoff may be over terrain with both vertical and horizontal space available limitations requiring maneuver. That is why airspeed, and not altitude, is life down low. Altitude is time. The extra time below safe stall altitude or safe engine failure altitude with the low ground effect takeoff may actually be life giving. The shortness of time below safe stall altitude using Vy is life at, but not before, that safe stall altitude. Airspeed is life when below that safe stall altitude.

The default of Vy climbout over the basic level in low ground effect takeoff and just over the obstruction climbout or even the cruise climb technique is from ACS. The standards are based on V-speeds. V-speeds are arbitrary, not conditional. The default of no zoom reserve, no pull is safer and the very beginning of the energy management turn, the safety turn. The wings level pull rather than yank and bank is also default for the energy management turn. The maneuvering ability to fly the airplane no matter what should be low altitude default. The maintain altitude no matter what is a high altitude default, and unfortunately also dangerous in the mountains or strong down draft. V-speeds can be programmed into the computer along with limits to pitch and bank angle, but the autopilot kicks off in rough going and says, "you have the controls." We err in return to ACS in flight reviews. Flight reviews need to cover the full range of variables encountered in a lifetime of flying. They need to draw on the art of flying based on the principals in "Stick and Rudder" and improved techniques. We have video and computerized data available now to show what is killing us. We need to modify standards based on that data rather than teach poor and inefficient technique where it is shown to be deficient or even unsafe.

To be fair, the ACS says only Vx or Vy as appropriate. Unfortunately the school solution is that one or the other is always appropriate, Neither is generally appropriate.