Why accelerate to Vy in ground effec w/ soft-field?

[tgrayson]

Does the flight path or flight attitude or both get flatter with altitude increase? I suspect we have been discussing both, interchangeably, throughout this discussion.

Both get flatter. I made that point earlier, based on theoretical considerations and MidlifeFlyer pointed it out based on experience. The increase in AoA due to a slower Vy slightly compensates for the shallower flight path, but not completely.

The angle of climb is described by this formula:

​

So you can see that thrust reductions reduce the angle of climb, as would increases in drag and weight. Our yoke mainly influences this formula through its effect on Drag.

Pitch attitude is the sum of our AoA and climb angle. For a given AoA, we can have a climb, level flight, or descent, depending on what our thrust setting is, which should remove the idea that the yoke "causes" our pitch attitude in a direct fashion.

 

[FDX8891]

I see. I hear you saying that I'm "clogging the forum" and you'd prefer to read responses by people who don't have any better understanding of the subject matter than you do, so that you don't feel intimidated. Do I understand you right?

Yes, I feel intimidated, that's why I gave my opinion amidst your answer(s). I'm sure your 4,000+ posts makes you an authority on a wide array of subjects, so excuse me if you take extreme offense to what I say.

The point I'm trying to make is that your answers to many of the things brought up in this forum are probably correct, but the way in which you describe them is done in such a way that I'm sure leaves many readers saying "huh"? Is that so offensive?

You seem to think I have an inferiority complex, when in all reality, I have absolutely no problem being told I'm flat out wrong. The problem I have is when an explanation is given to me described in radians, pi, and math formulas while using vocabulary which makes minimal effort in bringing the material down at a level at which *most* people can understand clearly and concisely. That's it!

 

[FDX8891]

Pay attention to the person he posts to. When he speaks to someone newer on here, he dumbs it down to be less technical. When he talks with me he will give a formula and explain it, because we understand it that way.

If he talks with fish, I go get a bag of chips and pretend I know what is going on.


Here is a translation, see if I can get this right:



I wouldn't argue this, but I'd be skeptical taking it for face value or presenting it to a student. That said, I have no translation until tgray gives more information into his thinking here.



This might be over simplified for you, but here:

Using a basic formula to demonstrate relationship of lift to speed and AOA we can write:

Lift = speed + AOA

Since lift always equals weight, whenever pitch is constant, we can assume lift to be a constant number. Let us keep them small, don't want to scare anyone with big math numbers, and say lift is 10. We have 5 speed and 5 AOA.

10 lift = 5 speed + 5 AOA

We can change AOA to but now we still have to keep lift at 10, so:

10 lift = some speed + 4

Some speed must be 6 to keep lift at 10. This is a clear demonstration of lifts relationship to speed and AOA. Speed and AOA vary inversely to keep lift constant when pitch is constant.

Knowing for sure now that speed varies inversely with AOA, and changes because AOA changes, we can refer back to this quote. Reread it and now understand the relationships, ignoring lift coefficient.

...did you reread!...? ok...

Lift coefficient = pi * AOA

So all the last part says is that changing AOA will make lift coefficient change. Here:

Remember pi from math class? It equals 3.14, so..

6.28 lift coefficient = 3.14 * 2 AOA

Let's change AOA from 2 to 3 and see what happens:

3 AOA * 3.14 = 9.42 lift coefficient

So we can see that is true.



Finally...


Reread this a few times over, paying attention to the comma that was added and substituting the bold word with: lift. Since lift is merely a difference in pressure, why not use a simpler word to reduce brain strain.




Did you word this funny or did I have too much to drink (my bday in 15 min:beer?



Ok T, a quick thought experiment:

Takeoff at sea level, trim for a perfect 75 knot climb. As you progress through 5,000, have you changed trim? How bout 10,000?

It has been a long time since I have done a progressive climb to 10,000+. However, the last time I did, I don't recall changing trim, even to 11.5 to get over Philadelphia.

Am I wrong? If I am right about this I am right about feeling the pressures on the yoke too. I'll explain after we agree on this though.




Mini - Are we on the same page with use of senses like instruments and such?

Thank you!

 

[shdw]

I'm sure your 4,000+ posts makes you an authority on a wide array of subjects

There is no need to be aggressive bud. Taylor is a wonderful source of information on a wide array of subjects. Like all of us he has more to learn, but the information he provides is well sourced and often highly accurate.

Opinions will always vary, of course.

Yes, I feel intimidated

Don't. Just ask, even if you think it is a dumb question. Tell him you don't understand it and ask for a simpler explanation.

Remember, we are all here trying to learn.

Thank you!

Your welcome! Oh and don't take offense to anything in this post, I'm just trying to offer suggestions.

If you'd like something else translated, ask, I'll do my best.

 

[tgrayson]

The point I'm trying to make is that your answers to many of the things brought up in this forum are probably correct, but the way in which you describe them is done in such a way that I'm sure leaves many readers saying "huh"? Is that so offensive?

Not at all offensive, but your previous post came across as rather belligerant, suggesting you had no interest in acquiring knowledge. If that isn't the case, then why don't you ask questions, rather than remaining silent? How can I know what is not understood unless people tell me? shdw is about the only person who regularly and reliably asks questions and he clearly is not afraid to show that he's ignorant of something, which is why he learns at a rapid pace. The fear of looking stupid is the biggest impediment to knowledge that there is.

 

[shdw]

he clearly is not afraid to show that he's ignorant of something

I resent that.

 

[SpiraMirabilis]

I resent that.

Why? It's a compliment. Whenever someone is learning something he or she will show that he or she is ignorant of it (either to themselves or others) before actually learning it. Those that aren't afraid to show other people this learn the fastest.

 

[tgrayson]

I resent that.

You shouldn't, it's a virtue that you should be able to find in the most learned people in the world. When I find someone who knows stuff that I don't, I ask them lots of questions, trying to steal their knowledge for myself, and I'm not the least bit concerned about appearing ignorant to them.

 

[MidlifeFlyer]

Tgrayson, you probably are the smartest guy alive, but I don't understand how 25% of what you say gets across to your students in the manner you intend it to.

I think that's really unfair. And I'm one who gets lost and phases out with some of the technical information myself.

First, I really doubt that tgrayson takes a fledgling student pilot who had trouble with 9th grade algebra and sticks the firehose of formulas and graphs down his throat any more than I expect my students to have a lawyers' grasp of regulations. People who know a lot fall into two categories: those who can bring it down to the level of the listener and those who don't have that skill to go along with the knowledge. From everything I've seen in tgrayson's posts (and it's not like I agree with him on everything), he has both the knowledge and the skill to teach to his audience.

Second, his "audience" here is CFIs and the fact that you or I may not be able to understand the aerodynamics and physics on the level he's explaining it doesn't mean that others aren't getting the benefit of it. To the contrary, the back and forth between he and others on those technical matters shows that others are in fact getting a lot out of it.

 

[shdw]

You shouldn't

I was joking, sorry figured it would be obvious.

 

[SpiraMirabilis]

I usually use the "Hey!! I resemble that remark!!"

 

[Mike H]

the shortest/best answer to "why accelerate to Vy in ground Effect?"

Because it's easier than if you were out of ground effect.