Angle, or Vx/Vy on takeoff?

[flyingcheesehead]

Since I was looking at FlySto earlier today, now I'm thinking I should start calculating an expected number and then comparing it with actual performance later.

Looking at a fairly random takeoff - 24ºC, ~3250lb, 5 kt headwind, slightly under 1000 feet pressure altitude. Should be about 1100 feet on the ground and 2450ish to 50 AGL according to performance charts. Should have lifted off at 65 and had 79 KIAS at 50 AGL, alas, I lifted off at 72 and was at 85 at 50' AGL; it was not a performance takeoff.

It looks like liftoff was at around 1400 feet, so 27% longer than book, but at 50' AGL I had traveled about 2400 feet horizontally, so at or even slightly better than book.

People really can't do 150% of book?!?

 

[MauleSkinner]

People really can't do 150% of book?!?

Oddly, in my experience only the people who claimed they used that particular safety factor.

 

[Roger Wilco]

I'm a low hour student pilot. During ground school both Vx and Vy, and their uses, were drilled into us. Now that I'm flying with an instructor, she has told me to add full power, rotate at Vr, and then pitch for 10° after liftoff. I asked her why I shouldn't simply fly Vx or Vy, and she said she has found the aircraft seems to fly better at a 10° pitch. I can easily do what she says, but I don't want to get any bad habits started.

Is this a big deal, or should I just pitch for 10° and go on?

So, Boom!,

Were you able to resolve the matter to your satisfaction?

 

[MauleSkinner]

So, Boom!,

Were you able to resolve the matter to your satisfaction?

OP hasn’t been seen since I asked the question over two weeks ago.

 

[Roger Wilco]

OP hasn’t been seen since I asked the question over two weeks ago.

As so often happens. But I'm genuinely interested in his CFI's explanation, and what he's learned from subsequent training and this thread.

 

[Boom!]

So…how did the conversation with your instructor go?

So, Boom!,

Were you able to resolve the matter to your satisfaction?

Sorry for the delay!

So I talked with my CFI about it and she said it's just easier for new students to give them an angle to fly as opposed to a speed. I told her I'd be more comfortable learning to nail Vx or Vy, and she agreed to keep it to that.

Fast forward a few flights later and I told her I'd be looking for a new instructor. I thanked her for her time and efforts on my behalf. She was demonstrating a lot of things, but we'd get to the end of our flight time and I'd only get in one iteration or so of doing those maneuvers myself. She would probably have adjusted her training so that she could give me more stick time, but I need an instructor that is inclined from the start to instruct me on what I need to do instead of constantly just showing me how it's done.

I'm not a perfect student, and I'm not an expert on what a CFI needs to do, but I know when I'm not learning as well as I should be, and in this case I'm just more comfortable learning with a new cfi than with this one.

 

[Roger Wilco]

Sorry for the delay!

So I talked with my CFI about it and she said it's just easier for new students to give them an angle to fly as opposed to a speed. I told her I'd be more comfortable learning to nail Vx or Vy, and she agreed to keep it to that.

Fast forward a few flights later and I told her I'd be looking for a new instructor. I thanked her for her time and efforts on my behalf. She was demonstrating a lot of things, but we'd get to the end of our flight time and I'd only get in one iteration or so of doing those maneuvers myself. She would probably have adjusted her training so that she could give me more stick time, but I need an instructor that is inclined from the start to instruct me on what I need to do instead of constantly just showing me how it's done.

I'm not a perfect student, and I'm not an expert on what a CFI needs to do, but I know when I'm not learning as well as I should be, and in this case I'm just more comfortable learning with a new cfi than with this one.

Thanks for the update. (I think) you made a good decision for the right reasons. I hope you have a better experience with your new CFI. As your training progresses just remember that, any time you need multiple conflicting opinions and dubious advice, PoA is here for you.

 

[StraightnLevel]

Sorry for the delay!

So I talked with my CFI about it and she said it's just easier for new students to give them an angle to fly as opposed to a speed. I told her I'd be more comfortable learning to nail Vx or Vy, and she agreed to keep it to that.

Fast forward a few flights later and I told her I'd be looking for a new instructor. I thanked her for her time and efforts on my behalf. She was demonstrating a lot of things, but we'd get to the end of our flight time and I'd only get in one iteration or so of doing those maneuvers myself. She would probably have adjusted her training so that she could give me more stick time, but I need an instructor that is inclined from the start to instruct me on what I need to do instead of constantly just showing me how it's done.

I'm not a perfect student, and I'm not an expert on what a CFI needs to do, but I know when I'm not learning as well as I should be, and in this case I'm just more comfortable learning with a new cfi than with this one.

There's nothing wrong with using several instructors. Every CFI has a different approach, and each one may work well with different types of students. Learn as much as you can from each, and know that you won't get to 100% without doing your own studying and solo flying.

 

[dtuuri]

So I talked with my CFI about it and she said it's just easier for new students to give them an angle to fly as opposed to a speed. I told her I'd be more comfortable learning to nail Vx or Vy, and she agreed to keep it to that.

You were right to ditch her. She shouldn't have agreed to teach you what you are "more comfortable with". She should have shown you the door. You'll both be happier.

 

[StraightnLevel]

You were right to ditch her. She shouldn't have agreed to teach you what you are "more comfortable with". She should have shown you the door. You'll both be happier.

Hmm.....what does the ACS say about Vx and Vy?

What is the problem with the student wanting to learn the procedures required for the checkride?

Personally, I would be uncomfortable with a CFI teaching something that doesn't match the standards in the ACS that the DPE will be looking for.

 

[dtuuri]

Hmm.....what does the ACS say about Vx and Vy?
What is the problem with the student wanting to learn the procedures required for the checkride?

Did you not see post #126? This thread was started with a grand total of 4 hours. That should be all the explanation required.

 

[M20K]

RV flying from KIYK

Even from 2400ft, won't the RV climb at least 1000fpm? Will the engine really overheat after the Takeoff roll and 1 min in climb?

 

[Fffflats]

Even from 2400ft, won't the RV climb at least 1000fpm? Will the engine really overheat after the Takeoff roll and 1 min in climb?

It’s (and you are) already hot from start, taxi, runup while density altitude in IYK in summer is more akin to 6K+. And heading west you’ve got serious terrain to get above. If you go north to have a slower climb then turn west, the terrain is even higher. If you go south to climb to go west, you might get a significant wind shear through the hose funnel of the pass. You may also generally have descending air along the whole ridge line. Can’t really circle east because of the restricted areas. Then you have thermal inertia (to which countering is worse with the higher density altitude). In the winter time, however, could point straight at Owen’s Peaks and clear it.

 

[Boom!]

You were right to ditch her. She shouldn't have agreed to teach you what you are "more comfortable with". She should have shown you the door. You'll both be happier.

Assume that I'm not sure why she should have ditched me and please explain.

Also assume that "more comfortable with" weren't the only words I said to her when we talked. By "more comfortable with" I mean I'd be more comfortable with learning to the standard I'd be held to by the DPE. She didn't disagree. The reason why I'm looking for another instructor was not because I'd be "more comfortable with" another instructor - it's because I wasn't getting the type of instruction I felt I needed. You'd know this if you read past the first paragraph in my post.

But please feel free to chalk it all up me knowing nothing about anything because I only had 4 hours at the start of this thread. I come to this point in my life having a lot of experience doing a lot of things, and I'm comfortable with the decision I made.

 

[Jon Wilder]

I'm a low hour student pilot. During ground school both Vx and Vy, and their uses, were drilled into us. Now that I'm flying with an instructor, she has told me to add full power, rotate at Vr, and then pitch for 10° after liftoff. I asked her why I shouldn't simply fly Vx or Vy, and she said she has found the aircraft seems to fly better at a 10° pitch. I can easily do what she says, but I don't want to get any bad habits started.

Is this a big deal, or should I just pitch for 10° and go on?

What speed does it give you at 10°? She may just know off the top of her head how the airplane performs at different attitudes. This is known as "attitude flying", where Pitch + Power = Performance. You really should learn it.

 

[dtuuri]

Assume that I'm not sure why she should have ditched me and please explain.

... I come to this point in my life having a lot of experience doing a lot of things, and I'm comfortable with the decision I made.

Having read all the paragraphs, I doubt you really want an explanation. Here it is anyway.

In, say, a Cessna 150, IIRC the IAS for Vx is 52 MPH, less in knots. Having a 4-hour (actually less than 4 in your case) beginner trying to hang on the prop that close to the stall speed less than 50' AGL is to flirt with death.

 

[Boom!]

Having read all the paragraphs, I doubt you really want an explanation. Here it is anyway.

In, say, a Cessna 150, IIRC the IAS for Vx is 52 MPH, less in knots. Having a 4-hour (actually less than 4 in your case) beginner trying to hang on the prop that close to the stall speed less than 50' AGL is to flirt with death.

Vx is 64mph and Vy is 73mph.

 

[Roger Wilco]

We don't climb with pitch

>snippety snip<

This is known as "attitude flying", where Pitch + Power = Performance. You really should learn it.

Am I the only one who is amused by these contradictory statements?

 

[Roger Wilco]

An unnamed CFI is teaching her students to establish a 10° pitch attitude for initial climb. And then what?

After liftoff, establish a target pitch attitude either visually or, if IMC (or certain big airplanes) by the attitude instrument. Then, cross-referencing the airspeed indicator, adjust the pitch as necessary to maintain the desired airspeed and trim for that speed. It's not complicated, it is universally accepted, and it works the same for a J3 or a 747. That's what I suspect that the Unnamed CFI intended to teach.

 

[dtuuri]

Vx is 64mph and Vy is 73mph.

Those are "normal" climb speeds. Ref: 1967 Cessna 150 Owner's Manual. Vx is 52 MPH at sea level (see page 2-9). Now, I understand you fly a C-152, but it is pretty much the same plane performance-wise. The point is, at 3 to 4 hours total time you should be working at altitude to associate climb attitudes with airspeed control. Heck, at that low of total time, you haven't even mastered P-factor control yet.

 

[Fffflats]

Hmm.....what does the ACS say about Vx and Vy?

What is the problem with the student wanting to learn the procedures required for the checkride?

Personally, I would be uncomfortable with a CFI teaching something that doesn't match the standards in the ACS that the DPE will be looking for.

There is a problem here that the ACS and the Airplane Flying Handbook and the PHAK are all wrong regarding Vx and Vy. Therefore a good CFI will teach something that doesn’t match but unfortunately most CFIs also have these concepts wrong too. For this matter most DPEs also probably don’t understand them.

Though here is CFI and DPE Catherine Cavagnaro with a look to Vx and how it changes with head or tail winds. You might find discussion similar to this in the glider handbook regarding optimum glide but you won’t find such anywhere else in FAA literature. (Even with the glider book, you won’t find adequate distinction as to what is optimum and differences for straight ahead vs turn. A small turn, as another commenter referenced, really could be better than Vx to go over. A zoom reserve really is a maneuver reserve.) Again, I generally avoid Vx. The Fly Onspeed organization recommends using onspeed AOA in lieu of and if you don’t have AOA then Vref (for current flaps) in lieu of.

The mystery of Vx

A pilot’s operating handbook can read like a mystery novel. While there is helpful information for flying an airplane, what they omit can be a real head-scratcher.

www.aopa.org

 

[Fffflats]

That would contradict the law of primacy.

and @Dan Thomas

Aviation Instructor Book may teach this “primacy” thing, but such is junk and not scientific. Exercise being repetition, recency, and intensity have merit. Bloom’s is also crap. And learning styles fit subjects not persons.

 

[Fffflats]

Vy has proved useful for climbing above turbulence or icing conditions.

You know what is better to clear icing layers? Accelerate below icing them zoom through to above. Meanwhile, as Vy has slowed on IAS as you’re at altitude (and now also lighter), did Vy really help you clear these things quickest?

 

[StraightnLevel]

There is a problem here that the ACS and the Airplane Flying Handbook and the PHAK are all wrong regarding Vx and Vy. Therefore a good CFI will teach something that doesn’t match but unfortunately most CFIs also have these concepts wrong too. For this matter most DPEs also probably don’t understand them.

Yes. Stall speed is also wrong, as are some of the basic concepts of physics stated in the PHAK.

Irrelevant.

A PPL student needs to learn the ACS, AFH and PHAK, as written. Trying to explain why the mandatory material is wrong isn't helpful to the student. If you try to explain the errors in the PHAK and POH to the DPE on your checkride, it's not likely to go well. The CFI needs to focus on basic flying skills and the knowledge required to pass the written, oral, and practical exams, and not create landmines with unnecessary contradictions.

 

[Initial Fix]

 

[Fffflats]

A PPL student needs to learn the ACS, AFH and PHAK, as written. Trying to explain why the mandatory material is wrong isn't helpful to the student. If you try to explain the errors in the PHAK and POH to the DPE on your checkride, it's not likely to go well.

Disagree. Best way to show you know the material is to be able to point out the errors. Most aren’t contradictions either, they’re straight up errors. Meanwhile DPEs I’ve talked with would much rather you know it right rather than correct meaning how it actually is over what the book says. They don’t want mere book regurgitations. They have to accept such but they want more.

 

[Dana]

Fast forward a few flights later and I told her I'd be looking for a new instructor. I thanked her for her time and efforts on my behalf. She was demonstrating a lot of things, but we'd get to the end of our flight time and I'd only get in one iteration or so of doing those maneuvers myself. She would probably have adjusted her training so that she could give me more stick time, but I need an instructor that is inclined from the start to instruct me on what I need to do instead of constantly just showing me how it's done.

Good call. My CFI handed me the controls shortly after takeoff on my first flight, and thereafter hardly ever touched the controls.

 

[midlifeflyer]

I'm a low hour student pilot. During ground school both Vx and Vy, and their uses, were drilled into us. Now that I'm flying with an instructor, she has told me to add full power, rotate at Vr, and then pitch for 10° after liftoff. I asked her why I shouldn't simply fly Vx or Vy, and she said she has found the aircraft seems to fly better at a 10° pitch. I can easily do what she says, but I don't want to get any bad habits started.

Is this a big deal, or should I just pitch for 10° and go on?

I think I know where that comes from. When you take off, you don’t want to hunt for, say, Vy by pulling pushing pulling pushing. You want to fly a pitch attitude that results in Vy. Basic pitch + power = performance.

There are a number of light airplanes in which 10° approximates the pitch attitude that will result in a normal climb. Crazy concept? Only if you think Garmin’s TOGA button, 7° in many light airplanes - is a crazy concept.

Two potential mistakes, IMO.
1. Thinking that 10° (or whatever) it is the goal rather than just part of the process of reaching the goal. The goal is Vx, Vy, or other target airspeed.
2. As a low hour student pilot, the approximation should be more out the window than on an attitude indicator

 

[midlifeflyer]

What she should be saying is after you rotate put the cowling on the horizon. This likely roughly equates to 10 degrees of pitch up on your attitude indicator

You might be surprised how many people have takeoff or landing problems transitioning to other aircraft by learning to target features on their trainer.

 

[luvflyin]

You might be surprised how many people have takeoff or landing problems transitioning to other aircraft by learning to target features on their trainer.

I have noticed that the bugs on the windshield do not coordinate with each other

 

[MauleSkinner]

I have noticed that the bugs on the windshield do not coordinate with each other

If pilots would fly the proper pitch attitude, the bugs would hit the right spot.

 

[Jon Wilder]

>snippety snip<

Am I the only one who is amused by these contradictory statements?

That was a quote from someone else, but the quote information got removed somehow. I'm trying to find the original post it came from.

EDIT: I can't find the post it came from and not even sure how that got in there but I never would have intentionally said that. I'm one of the biggest opponents of "pitch for airspeed, power for altitude" mentality.

 

[Jon Wilder]

which is why pitching to an angle instead of an airspeed is improper technique that can get pilots killed.

This is why we don't change pitch without power. They're way too closely related to treat them as if they control separate flight parameters (pitch for airspeed, power for altitude )

 

[MRC01]

This is why we don't change pitch without power. They're way too closely related to treat them as if they control separate flight parameters (pitch for airspeed, power for altitude )

True. But power is more than just the position of the black, red and blue knobs. It also depends on density altitude. On takeoff, full power, all knobs forward, pitch angle is very different at sea level versus 7500 DA. That's why "full power, pitch for indicated airspeed" always works, and "full power, pitch for angle" can kill you.

PS: with experience in a specific plane, you can use pitch angle as a guide if you adjust it for conditions. In my airplane I know the full power Vy pitch angle is roughly 15* at sea level and 5* at 7500 DA. Airspeed is still primary, but this gives a helpful secondary target.

 

[Jon Wilder]

True. But power is more than just the position of the black, red and blue knobs. It also depends on density altitude. On takeoff, full power, all knobs forward, pitch angle is very different at sea level versus 7500 DA. That's why "full power, pitch for indicated airspeed" always works, and "full power, pitch for angle" can kill you.

PS: with experience in a specific plane, you can use pitch angle as a guide if you adjust it for conditions. In my airplane I know the full power Vy pitch angle is roughly 15* at sea level and 5* at 7500 DA. Airspeed is still primary, but this gives a helpful secondary target.

Yes, we pitch for an airspeed at full power for a climb. It's when we get into descents and approach to land that students take it way too literally. They fixate on that airspeed indicator with no regard to the difference between airspeed and indicated airspeed.

Case in point...forward slip to land. The second you turn that airplane sideways, the IAS tanks because the pitot tube is no longer pointed into the wind. The problem is compounded in a plane like a 172 that only has a single static port on the pilot side. You cannot rely on IAS when deciding how much to pitch down during the slip because of this.

On top of that, because pneumatic instruments lag, flying the airspeed indicator leads to chasing the needle, which leads to a dangerous cycle of overcontrolling and lagging reactions.

 

[Dan Thomas]

and @Dan Thomas

Aviation Instructor Book may teach this “primacy” thing, but such is junk and not scientific. Exercise being repetition, recency, and intensity have merit. Bloom’s is also crap. And learning styles fit subjects not persons.

What are your aviation credentials and experience?

 

[MRC01]

... On top of that, because pneumatic instruments lag, flying the airspeed indicator leads to chasing the needle, which leads to a dangerous cycle of overcontrolling and lagging reactions.

Yes that (chasing the needles, causing oscillation) is also bad. Just because airspeed is primary doesn't mean the pilot must focus solely and entirely on airspeed alone, ignoring secondary references. One must use secondary references and apply experience & judgement.

 

[Ed Haywood]

Let the Richard measuring contest begin.

 

[Roger Wilco]

Yes, we pitch for an airspeed at full power for a climb. It's when we get into descents and approach to land that students take it way too literally. They fixate on that airspeed indicator with no regard to the difference between airspeed and indicated airspeed.
..

I was thinking of a way to respond to post #193, but your subsequent posts suggest that you’re hopelessly confused.

 

[geezer]

BOOM, I am a skilled trainer/instructor, but not flight.

First and foremost, the instructor's training methods should match the students learning style.

I have had many instructors, but the first 4 were great. 1 flight with each.
Piper Cubs, full brief before starting the engine by hand (instructor), then I taxied to the runway and onto it. I am sure he had his hand on the stick, but told me when to lift the tail, then raise the nose for takeoff. No VX or VY, just pitch to clear the roof of the building ahead by 50 feet.

Out over some farms, and 2000 feet AGL, he set power just below enough to maintain altitude, and told me to maintain altitude. I spent about 5 minutes slowing through the change of airflow sound, quivers of the plane and stick, nose drop, stick forward to recover, and slow again.
I found the sound and feel that produced the least altitude loss, no breaks.

He said that was the sounds and feel of just before touch down when landing.

Back at the airport, he talked me through the approach, flare, and drift down to the runway.

4 instructors, 4 take offs, 4 landings, without any perceptible input from the instructors.

Moved, went to the nearest airport, terrible instructor.

Went to another airport, Cessna 150, great instructor, rapidly learned a lot more.

The big point is fly with an instructor who teaches the way YOU learn, study all the manuals, and KNOW the details for the plane you are flying. There are no shortcuts.

Keep coming back here, update us on your progress.