Scottsdale FSDO

christina3hunt

christina3hunt

New Member
Any of the pilots in the Phoenix area taken a checkride at the Scottsdale FSDO??? Well I took mine and definitly failed within the first 2 hours... He didn't like my discussion of lift and the downward deflection force. And also who knew that the lift vector was perpindicular to the relative wind. Well, I didn't so here I am... He said I wasn't confident at the white board. I've never failed a checkride but I thought they were supposed to ask you if you would like to continue on with the rest. But, apparently not because now I have to go finish everything pretty much and drive an hour again to the FSDO.

Anyone familiar with any of the guys at the scottsdale FSDO???

And also can anyone help me with there understanding of the downward deflection force (as it has to do with lift)???
 
Sorry to hear about the first time round.

I will try to explain the lift question after dinner. Need food.
 
Hi Christina,

The "downward deflection force" can be divided into two components:

1. Downwash produced by the lower air pressure above the wing.

2. The deflection of incoming air from the lower side of the wing.

In either case, Newton's Third law is at work: the airfoil exerts a downward force on the airmass, and in return the airmass exerts an upward force on the airfoil.

Moxie, tgrayson and the others can add or correct the above info...

I hope this helps:).

Reference: PHAK Chapter 2, page 6
 
Its amazing how many pilots view Newtons 3rd law and the diagram where the air particles are hitting the lower surface and bouncing off at an angle. In a continuous flow this simply can not happen. To correctly use the "water ski analogy" you would have to completely submerge the water ski under water and move it at an AOA to the water flow. Having done so you would not find individual water molecules bouncing off the bottom of the ski, but rather a continuous water flow around the ski, in just the same manner as that other fluid, air.
We know that it is the relative slowing down of the airflow on the lower surface due to the continuity principle and the subsequent increase in relative pressure on the lower surface due to the momentum principle that results in part of the lift force. What does happen is that due to the entire effect of the flow field around the wing a change in direction for the airflow does occur as the airflow departs the trailing edge of the wing. This change in momentum for the entire flow field is often quoted as equaling the total lift force produced by the wing. It is easy to make the intellectual jump that this “downward deflection” of the airflow means the same thing as air particles bouncing off the bottom surface. This is not, what is happening.
[FONT=Garamond, Times New Roman, serif]This is a very important point. The downward deflection of the airflow is an effect of the lift produced by the wing, not a cause of it. The wing is capable of “feeling” only the pressure distribution and friction on its surfaces, nothing more and nothing less.[/FONT]
[FONT=Garamond, Times New Roman, serif]Unfortunately, this explanation has been used for so long by so many that you can find it almost anywhere. It can be found in numerous non-aero engineering books and I know of at least one commercially available video course which still uses it. [/FONT]
[FONT=Garamond, Times New Roman, serif]Well, if this “bouncing off the wing” idea is bogus, what is the one exception? Remember our basic definition of pressure, that it is the cumulative impact of the individual molecules vibrating and bouncing into each other or some surface. Also remember that as you go higher in the atmosphere that the air becomes less dense. This is another way of saying that the individual molecules are getting farther and farther apart until, at the very edge of space, they are very few and far between. This means that no matter how each individual molecule vibrates or moves about; it is so far from its nearest neighbor that they never come in contact with each other. If they can not bounce into each then there can be no pressure. It is just that simple.[/FONT]
[FONT=Garamond, Times New Roman, serif]But being so far apart does not mean that each individual molecule has any less mass to it. Granted it is a small amount of mass, but the rules of physics still apply, and to hit one of these molecules and accelerate it in some direction requires a finite amount of force. If you can take some kind of vehicle at the edge of space and fly it fast enough to hit enough of these widely spaced molecules, you just might be able to generate enough force to support the vehicle. This is precisely what happens to the Space Shuttle (or any other space vehicle) as it re-enters the outer edge of the atmosphere traveling at 10,000 miles per hour. [/FONT]
So what Im trying to say is that Bernoulli’s principle is causing most of the lift, you can demonstrate this by doing a stall (removing Bernoulli’s principle) and seeing a major loss in lift

I happened to be studying this in class and writing an essay on this subject, not like I really know
 
Taking a checkride at the Scottsdale FSDO is so tough that ATP started sending their CFI applicants up to Vegas. Or maybe the training at ATP was the problem. Who knows, never did any training there.

That doesn't seem right to me, but the school I work for has had plenty of trouble from Scottsdale as well. Study up on the subject you missed, plan for a long checkride, don't worry about the failure (failing a CFI ride is common) and go in with confidence! Convince the examiner you know what you are talking about with your voice and body language. Pretend he/she is a student who knows next to nothing, not an experienced pilot.

Good luck.
 
And also who knew that the lift vector was perpindicular to the relative wind. Well, I didn't so here I am...

I'm trying not to laugh but if you don't know, you aren't ready to be a CFI. Really.

Now be careful to not blame the examiner, the post just before mine seems to be heading in that direction. Think of it as he did you a favor by giving you cause to dig deeper into the well of true knowledge.

And your sentence construction leaves something to be desired. "And also..." (sound of gnashing of teeth) By chance, are you related to Jr Miss South Carolina?
 
Further elucidation required....

My previous comments do not mean you should be judged solely on that which you don't know even though you are at a level where you are expected to know; after all, you could be very good at other aspects of instructing. For example, you may be very proficient on the FARs or in the actual flying of the aircraft.

However, my point is, to use my example, transferring knowledge of the rules & regs does not make a safe student. Nor does your ability to control the aircraft. Distinctly, the point is the knowledge of how to keep an aircraft in the air is most important. A knowledge of the FARs or proper radio communication techniques will not prevent the student from mismanaging the aircraft. To this end none of these things are as important as a sound understanding of the physics involved in maintaining flight in whatever configuration. And it is highly unlikely the student will perceive value in you if you do not have that understanding.
 
Your right, it is a place for support. That's the great thing about this site. It's an up front, in your face, direct to the point kind of support. There is no sugar coating to make answers come across without......."hurting someone's feelings." You asked for help and advice, and well, that's exactly what you got. These are people who are or have been to where you are trying to reach. If there answers come across in a manner to you don't like, well.....grow so skin. You asked for help and you got it.

On a side note, if I was the examiner and you came in for a CFI initial and couldn't tell me that lift was perp. to the relative wind, I would probably be laughing while filling out the pink slip. Come on now......:banghead:
 
I don't know how it is around here but I do know how it is in the serious business of teaching. And I know I usually come off too brusque but please, for your sake and the sake of your students, try to see the reason for why it is as it is.

Learning to fly is serious business, teaching is a very serious endeavor which carries awesome responsibilities. Quite factually, you can either make or break a student simply by how you respond to certain criteria which dictate the success or failure of you, your students, your employer, and the industry at large. See, the entire industry is founded on the knowledge AND the attitude of the CFIs.

Tell me I'm exaggerating or tell me I'm all washed up, I don't mind. But understand this, the CFI shouldn't linger in the affective domain lest they tuck tail and run. No less than your students are counting on you to fully prepare them to achieve their goals. To that end, it aint about you, it's about them...and much more.

God forbid you should find one of your students died in a crash which you think was preventable. Sound knowledge goes a long way. Their knowledge begins with your understanding. As a CFI you have an amazing ability but with that comes responsibility.

I really do want to see you succeed, but it has to not be predicated on relaxed standards. Literally, be all you can be.
 
Okay- first of all I just want everyone to know that I take being a CFI very seriously. I know it is an extremely important responsibility. CFI's are the building block upon which the aviation community is built. Our success or failure in teaching has a direct effect on our students. But, that being said I do not expect to know everything at this point in my career. Anything that I do not know I try to do my best and understand, but there is always something. I WILL teach my students safety and responsibility in flying.

As far as not knowing that lift was perpindicular to relative wind. I am very knowleable about lift and and the aerodynamics behind it . Somehow through my studying I missed this little detail. I actually went back and looked at a lot of books and It really doesn't come right out and say this in most books. You just have to assume it from the drawing. This is not why the examiner failed me. He just said this is something that I should know without looking up. Which is obvious to me, I realize its an important detail in vector analysis. He failed me because he said once I got up to the white board that I seemed uncomfortable. This is mostly because I like the conversational style of teaching and I am not exactly an artist. I find it sometimes easier to just show a computer generated picture that illustrates what I am trying to convey.

I also was not trying to blame the examiner. The examiner that I have is a very very nice guy. I fully understand why he want me to become more comfortable standing up and talking about a subject. Because in the end I will be a teacher and I should be able to stand up comfortably and teach something to my student. This is what he feels is important and I respect that. When I become a CFI I can employ whatever strategy works for me.

I appreciate all of those who have given me constructive criticism on this site and not made me feel like a failure.;)
 
Christina,

Look, this seems to be a case of good cop bad cop. I am going to be the good cop for just a little while. I am sure you will get your CFI no problem, but you will have to study up some more.

I am very knowleable about lift and and the aerodynamics behind it . Somehow through my studying I missed this little detail
Click to expand...

Well thats not actually such a little detail. Its pretty much the entire shabang about lift. Lets think about this a second. What is the relative wind? Its the same wind you feel as you run across a parking lot, and its the wind going over the wings as an airplane slices through the air. That relative wind goes over the upper camber of the wing and is then turned and deflected downward because it is a fluid. When the wind is deflected downward, it causes and equal and opposite force to act on the wing. And that force acts up obviously right? Keeping the airplane up right? So the relative wind is coming from the front of the aircraft, over the leading edge and is then being deflected at a shallow angle backwards. Don't let my explanation confuse you, its not being deflected straight down, just down at a shallow angle. And since it is come from a horizontal position, and since the lift is acting upward, it is perpendicular to the wind... Something tells me you really did know that.. But in the end it incredibly important that you can explain that to your students! It amazes me how man pilots there are out there that don't know hardly any basic fundamental aerodynamics.

A word to the wise, better study up on your aerodynamics of a turn, adverse yaw, centrifugal force, load factors, the effects of bank angle on stall speed. Know how and airplane turns concerning the loss of the vertical component of lift. Know where the lift vector points in a turn. Know where weight acts (always towards the earth), know where centrifugal force acts. Know how the tail works - its an upside down wing - be able to explain how the air is deflected on the tail. Be able to tell him what happens to the downwash as you put flaps down. Also be able to discuss with him the interaction of lift and drag... As lift increases so does induced drag. Be able to tell him all the diffent kinds of parasite drag. Know your stuff inside and out.

Of course this is beating a dead horse... He failed you on your confidence... However take the above as advice, because if you get the same guy again he made hound you again on this stuff.

Now moving right along to your confidence problem. Does your family live in Phoenix or near by? Significant other? Friends who don't fly? If you said yes to any of the above then here is some more advice. Since it may take your FSDO guy a while to get back with you as it usually does, go find one of the above and teach them everything you know about how a plane flies, how a chart works, how to flight plan, how to work a weight and balance, weather, whatever. Make them an expert and make them ask you questions.

AND, one final thing. Some FSDO's absolutely love their failure rate for initial CFI's... I have heard of FSDO's with 92% initial CFI failure rates... Don't beat your self up too bad.
 
I'll second my earlier post and the above post from skycowboy. Don't beat yourself up about this. Practice in front of the white board and bring plenty of confidence to your next checkride. Some people who aren't even CFI's will try to tell you what you should and shouldn't know. Everyone is an expert until they have to take the checkride themselves. They'll say you should have done better in a situation they have never been in. Don't worry about what they say. This is probably the most difficult checkride you'll ever take, so spend plenty of time re-preparing and go into the next ride ready to kick some ass.
 
Richard, thanks for your input, it's certainly appreciated.

However, the 'tough love' approach doesn't translate well online so it's best to avoid it.
 
Roger, Doug.

One text I highly recommend is Aerodynamics for Naval Aviators, by H.H. Hurt, Jr. Library of Congress Catalog ISBN 1-56027-140-X

ASA publishes, less than $20.00.

Here you will find, "The pressure distribution on the airfoil now provides a net force perpendicular to the airstream--lift."

And, "THE BASIC LIFT EQUATION. Lift has been defined as the net force developed perpendicular to the relative wind. The aerodynamic force of lift on an airplane results from the generation of a pressure distribution on the wing."

You do not have to be a math major to understand the book. Get the book and read it.
 
That's actually a very good suggestion, I think I still have a copy of that in the closet, along with a few skeletons from my ERAU days. ;)
 
Congrats on the Oral portion! Good luck with the flight test. I have my CFI-I initial scheduled with the dreaded OKC FSDO next Wednesday. Almost a guaranteed bust. The fail rate for initials is hovering around 90%. Doesn't make a person to confident going in...............we'll see. :banghead::banghead::banghead:
 
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