MidlifeFlyer
Well-Known Member
With all due respect, I think that's nonsense.
Landing Technique Question.
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CoffeeIcePapers
Well-Hung Member
I teach Pitch(AoA, technically) for Airspeed, Power for Altitude for landings and slow. Even though the terminology may be incorrect, when teaching primary students, it seems to work for me.
I know there are other ways to teach it, and realize that other methods may work better for other instructors. To each his own. If I get a student who has learned a different method, but is still able to achieve the same results, I don't try to reteach them my methods.
This is the same type of debate as the wing low vs. crab and kick crosswind landing method. There are different ways to teach it, and each way has its pros and cons.
I know there are other ways to teach it, and realize that other methods may work better for other instructors. To each his own. If I get a student who has learned a different method, but is still able to achieve the same results, I don't try to reteach them my methods.
This is the same type of debate as the wing low vs. crab and kick crosswind landing method. There are different ways to teach it, and each way has its pros and cons.
subpilot
Squawking 7600
Nope. You keep the pitch fixed and advance the throttle. This is when the airplane will accelerate. You retrim when you are done accelerating.
I know I don't have graphs to support this method and it is not scientifically correct. I do know that in the SAAB 340, if I am flying with autopilot and advance the power levers the computer does the same thing I do. Maybe we should get on these autopilot programmers for not using the correct concepts to fly passengers around safely.
tgrayson
New Member
I know. But you make this judgement having expended little effort in mastering the technical knowledge that underlies this subject.
tgrayson
New Member
And thus you prove my point.
By keeping your pitch fixed when you increase thrust, you are decreasing your angle of attack. You're making the same angle of attack change that you would if you merely pushed forward on the yoke without changing the thrust.
If you didn't push forward on the yoke when you increased thrust, you would merely climb, at approximately the same airspeed.
So in reality, you have never demonstrated that the throttle controls airspeed; if you managed to convince anyone that you could, they're under some confusion between pitch and angle of attack.
tgrayson
New Member
One characteristic of successful scientific theories is that they unite a variety of seemingly unrelated phenomenon under one roof.
For crosswind landings, the underlying idea is that the velocity vector of the aircraft needs to be pointed into the wind. Period. Once that concept is established, you can talk about methods of doing that. The wing-low and crab are pretty much the same, conceptually. The only slight difference is where the nose is pointed, which isn't directly related to which way the airplane is moving.
subpilot
Squawking 7600
I never said that your wrong or that angle of attack is not the underlying fundamental that is making everything happen. I think the point of all the debate is that we are all doing the same thing but there is more than one way to skin a cat (explain how to fly an airplane) and I firmly believe that my way is very easy for a student to pick up on and it will not hinder them in the future. I still think this way when I fly. I don't think of what the angle of attack is doing while I fly. I use pitch to control altitude and power to control speed.
meritflyer
Well-Known Member
I believe this is also the way the FAA says to fly an ILS.
tgrayson
New Member
You said, and I quote:
"I then demo that you can also control speed with only pitch or only power."
But I will accept that you now agree the latter part of the sentence is false.Probably is.
As long as they
- don't try to develop a more technical knowlege of aircraft flight,
- never get caught behind the power curve and low to the ground,
- never fly a glider
This works in most flight regimes. If you're doing 121/135 work, then you will probably never experience a regime where it breaks down.
tgrayson
New Member
Most people teach this and so do I. However, I do spend a ground session explaining why this works and why it's not a true aerodynamic explanation.
ILS airspeeds are far on the front side of the thrust curve, so changing your AOA to change your position on the glideslope will work as expected.
MidlifeFlyer
Well-Known Member
No, I make that judgment based on having seen the practical application of it - that pilots trained with either method will either do or not do the correct thing.
I've seen pilots pitch for altitude when low and not add power to stop the decay of airspeed. I've also seen them pitch for altitude when high and not reduce power to control their airspeed.
I've seen pilots power for altitude when low and not make the necessary pitch change to prevent initial ballooning. I've also seen them reduce power for altitude when high and then fail to reduce pitch to maintain their approach speed.
I've seen pilots make appropriate pitch and power inputs in both cases no matter which way they were taught.
subpilot
Squawking 7600
How is that changing my position. Just because I agree that you are scientifically correct does not mean that I am teaching it wrong. Doesn't both changes to pitch and to power affect the AOA? Then I don't understand why our method is wrong to you. 99% of pilots out there do not need to understand aerodynamics as well as you do to safely fly a plane and the 1% that do will learn it. A basketball player doesn't need to understand the physics behind a three pointer to shoot one into the basket.
tgrayson
New Member
That's a proficiency issue and has no bearing on which explanation is correct. You suggested that there is no truth to this topic, yet you have not studied it, nor does it appear that you have any plans to do so.
That attitude is really at odds with the attitude you display on other aviation topics. If you change your mind, I'd be happy to make some reading recommendations.
tgrayson
New Member
Because you said you can change airspeed with power alone.
Let's not use "pitch" here, because pitch is the result of an AOA or thrust change and not causal itself. E.g., pushing on the yoke in slow flight may result in a *higher* pitch attitude eventually, because the drag reduction may enable the aircraft to climb.
Thrust *can* affect your AOA if the thrust line does not go through the CG. If the thrustline is above the CG, then advancing the throttle can produce an airspeed increase. If the thrustline is below the CG, then thrust can produce an airspeed decrease. These are secondary effects and there are others, but they are specific to particular airplanes. For a generic analysis, you assume that the thrustline is in line with the CG. In this case, thrust will not affect the AOA.
I detailed the problems with your model above, nicely numbered, so I won't repeat them. Your method works during normal flight regimes, but for reasons that differ from what you said.
There are a lot of student pilots out there who know you fix airspeed problems by pushing on the yoke, so it obviously doesn't take an aerodynamics degree. If you get very low and very slow on final in an aircraft with limited amounts of thrust, that's the only thing that's going to save you. You've got to push down in order to go up. The pitching for altitude model just won't cut it, even ignoring the possibility of a stall.
tgrayson
New Member
I sorta assumed this was obvious. Surely everyone is familiar with the "U" shaped drag curve?
No, I think this is where you get the "I'm moving the yoke on the ramp and my speed isn't changing" type responses.
If a pilot increases the throttle in level flight, retrims (perhaps without thinking about it), and continues along at the same altitude but a higher airspeed, does he perceive that he has changed his speed with the throttle or the yoke?
See what I mean?
If a pilot increases the throttle in level flight, retrims (perhaps without thinking about it), and continues along at the same altitude but a higher airspeed, does he perceive that he has changed his speed with the throttle or the yoke?
See what I mean?
CoffeeIcePapers
Well-Hung Member
Since he is retrimming, he is lowering his angle of attack. I teach all of my students that if they increase power during straight and level, they will need to reduce the angle of attack to maintain altitude. I also teach them that with a static power setting, if they reduce the angle of attack, they will gain airspeed. They perceive what is going on in both instances.
MidlifeFlyer
Well-Known Member
Ah! We're talking apples and oranges. My position on this is pretty much the same as subpilot's. I am looking at it from a "teaching someone how to fly an airplane safely and proficiently standpoint," not from a "there's no such thing as a curveball" standpoint. I'm thinking in terms of what method of teaching altitude and airspeed control will result in a pilot who handles sudden and significant windshear on final and just don't find the higher physics of the issue in this case particularly important or helpful.
I thought that's what the OP's question addressed and I wouldn't be a bit surprised if neither of the two instructors he was dealing with have a clue of the higher physics involved.
tgrayson
New Member
You don't need the higher physics on final, if they were drilled into you from the very beginning. The power for airspeed model has the flaws I mentioned before, and the reason it has those flaws is that it's incorrect. Won't affect the pilot under most situations, but could under some extreme conditions.
They probably don't, although AOA controlling airspeed is hardly higher physics. However, even if they didn't understand the physics, it still remains that one was aerodynamically correct and the other was not. So correct physics can be taught, even if the teacher doesn't have an engineering degree.
I'm still disappointed that anyone would knowingly teach something that was incorrect, when correct information is readily available, is straightforward to apply, and has a much broader applicability than the somewhat more intuitive model.