Pull the power when turning base.

[Henning]

Not by my understanding of the definition of "backside of the power curve" which is illustrated nicely here:

That's flying the PLANE on the back side, not the approach, the same principle applies. When you can reduce power and still maintain your desired vertical track, you are on the frontside of the power curve, you have excess energy. When you have to add power to maintain your desired vertical path, you are on the backside, you have bare minimum with the engine included. The adjustment lies in that the graph is keyed to level flight and the approach to a descending glide slope.

 

[timwinters]

Whatever...

The only time I've truly been behind the power curve on an approach was purposely when doing a short field landing at an 800' strip. And it's quite obvious.

On a "normal" stabilized power-on approach you are nowhere near being behind the curve because you're well above stall speed...indicated even. The ASI will read below stall speed when truly behind the curve.

 

[Henning]

Whatever...

The only time I've truly been behind the power curve on an approach was purposely when doing a short field landing at an 800' strip. And it's quite obvious.

On a "normal" stabilized power-on approach you are nowhere near being behind the curve because you're well above stall speed...indicated even. The ASI will read below stall speed when truly behind the curve.

Again, that is the plane's stall power curve, not the approach's

 

[timwinters]

Again, that is the plane's stall power curve, not the approach's

Ahh...I get your point now but that is a Henning concept, not an aviation concept.

At least not one that I've ever heard of.

 

[Henning]

Ahh...I get your point now but that is a Henning concept, not an aviation concept.

At least not one that I've ever heard of.

That is an energy management concept with a term widely used. "Behind the power curve" is used in reference to many things including people's ability to think. "That dude is just a bit behind the power curve."

When addition of power is required to meet a referenced goal, one is 'behind the power curve' regardless the reference.

 

[poadeleted20]

If you can't make the runway if the engine quits, you are flying an approach on the back side of the power curve by definition.

I gather you're unfamiliar with the definition of "the back side of the power curve". You can learn about the front/back side of the power curve at Dr. John Denker's excellent "See How it Flies" web site.

http://www.av8n.com/how/htm/power.html#sec-speed-change

To make a long story short, the front side of the power curve is where total drag decreases as speed decreases, so you need less power to maintain altitude as the aircraft slows. The back side of the power curve is the region of the power required curve where due to sharply increasing induced drag at higher AoA, it requires more power to maintain altitude as speed decreases. In a light single, you will not be on the back side of the power curve until you get very close to stall speed -- a lot closer than 1.3 Vs0 or any speed you'd want to be at on final (even down to around 1.15Vs0 for a really short field operation).

Note that this is something you can experiment with yourself, starting at Vy or so, and slowing in small increments seeing how much power you need to hold altitude at each speed. Initially, the airplane will climb as you slow unless you reduce power. Eventually, somewhere near stall, you'll find you need to increase power to keep from descending as you slow further, and that's where the back side of the power curve begins. This is something an instructor can demonstrate to a primary trainee as part of pre-solo training, and I recommend doing that so the trainee understands the concept, and why you don't want to get too slow.

 

[poadeleted20]

That's flying the PLANE on the back side, not the approach, the same principle applies. When you can reduce power and still maintain your desired vertical track, you are on the frontside of the power curve, you have excess energy. When you have to add power to maintain your desired vertical path, you are on the backside, you have bare minimum with the engine included. The adjustment lies in that the graph is keyed to level flight and the approach to a descending glide slope.

You've developed your own personal definition there, and it's one not in any aerodynamics book. And it certainly has nothing to do with whether or not you can make the runway if the engine quits.

 

[poadeleted20]

That is an energy management concept with a term widely used. "Behind the power curve" is used in reference to many things including people's ability to think. "That dude is just a bit behind the power curve."

When addition of power is required to meet a referenced goal, one is 'behind the power curve' regardless the reference.

As Tim said, that is clearly a "Henning definition", and you won't find it in any FAA or aerodynamics reference source.

 

[Henning]

Yet you find it in non aviation context...

 

[poadeleted20]

Yet you find it in non aviation context...

This is not a non-aviation context. BTW, H.H. Hunt's "Aerodynamics for Naval Aviators" might also be a good read for you, and I think you can even find it as a .pdf download on the internet. Might help you with the terminology used to teach people this material.

 

[Henning]

Ok, if you have to maintain power on to maintain your vertical glide path, just what is it that you specify that condition to be? Which semantic phrase would you choose Ron?

 

[mikea]

My instructor had me do that for a whole day

It's pretty awesome. Not sure of many planes that sink faster then a 235 when the power is pulled but I managed just fine. So will you.

Saratoga. Also glides like a rock.

 

[poadeleted20]

Ok, if you have to maintain power on to maintain your vertical glide path, just what is it that you specify that condition to be?

Umm...flight in a heavier-than-air aircraft on a flight path shallower than its power-off glide angle in its current configuration at its current speed? And going from the front side to the back side of the power curve would not change that at all.

 

[warthog1984]

Ok, if you have to maintain power on to maintain your vertical glide path, just what is it that you specify that condition to be? Which semantic phrase would you choose Ron?

Flying a stabilized approach?

 

[poadeleted20]

Flying a stabilized approach?

Thanks for simplifying as well as demonstrating why that's an important concept.

My guess is that the OP's fundamental problem is a lack of understanding of or failure to properly apply the concept of "trim for airspeed, power for vertical speed", and that can best be demonstrated and learned in the less-distracting environment of the practice area than in the traffic pattern. Why do you think every primary flight training syllabus calls for all that slow flight stuff before starting on traffic patterns, approaches, and landings? You know, all that "maintain 75 knots at 2000 feet, now climb to 2500 while holding 75 knots, now accelerate to 90 knots while maintaining 2500 feet, now descend to 2000 t 90 knots, now slow to 75 while maintaining 2000" stuff. Or maintaining 75 knots and a content altitude while running the flaps up and down.

That's where the trainee should be learning the relationship between attitude/power/trim and airspeed/vertical speed, and what I fear was not fully comprehended by the OP before moving on to the traffic pattern to start working on landings. The key to this is the instructor ensuring that the trainee can correlate those concepts to what's happening in the approach to landing, and in my experience, many instructors (even the old heads who learned in Cubs or Stearmans) don't do that well. They often fail to explain why we're doing all that pitch/power stuff out in the practice area first, and how it relates to an approach to landing.

 

[eetrojan]

Ok, if you have to maintain power on to maintain your vertical glide path, just what is it that you specify that condition to be? Which semantic phrase would you choose Ron?

Isn't this the condition called "dragging it in"?

 

[warthog1984]

Isn't this the condition called "dragging it in"?

Dragging a plane in refers to when you are flying very close to or on the back side of the power curve.

A stabilized approach refers to a power-on approach where if you lose power, you will not make the field.

A B-52 pattern refers to a stabilized approach requiring 2 or more counties, and is often seen at pilot mills and student solos.

 

[MAKG1]

Ok, if you have to maintain power on to maintain your vertical glide path, just what is it that you specify that condition to be? Which semantic phrase would you choose Ron?

How does "out of gliding range of the runway" sound?

Getting behind the power curve is not something you see in a normal approach, even with power. But I disagree that it's "only seen near stall." In fact, the short field approach speed is pretty close to max L/D, where the power curve turns over. It doesn't take that much slower to get it behind. That's when you start needing A LOT of power, and it's the real meaning of "dragging it in."

While it's a huge effect in slow flight, you do not need to have the stall warning going off -- or really even be all that close to it -- to get into the region of reversed command. Reversed command is synonymous with being behind the power curve. It means pulling back on the yoke with no power change makes you go down.

I second the Denker book. It has a lot of discussion on this issue.

 

[poadeleted20]

A stabilized approach refers to a power-on approach where if you lose power, you will not make the field.

There is a lot more to the Stabilized VFR Approach than that. See the Airplane Flying Handbook or the pamphlet I linked earlier for details, but it mainly involves maintaining a stable glide path on the desired angle and the stable desired airspeed.

A B-52 pattern refers to a stabilized approach requiring 2 or more counties, and is often seen at pilot mills and student solos.

 

[poadeleted20]

Reversed command is synonymous with being behind the power curve. It means pulling back on the yoke with no power change makes you go down.

I like that. Of course, unless you're right at the stall already, you'll briefly climb until the increased drag overcomes inertia, but a descent will be the eventual result when things stabilize.

 

[Henning]

Flying a stabilized approach?

How do you stabilize it? I can fly a perfectly stabilized approach in a glider, no power needed. Will it cause you to have a bad day if you lost power?

 

[RalphInCA]

Just got back from my lesson. Pulled power back to idle right before turning base, 2nd notch of flaps, turned base, trimmed for 70, called base.

Then final, power still back, last notch of flaps, called final, proper pitch attitude, adjust power as necessary to maintain glide slope.

Worked out well.

Now just need to smooth out my flare a little.

Getting there!

 

[poadeleted20]

How do you stabilize it? I can fly a perfectly stabilized approach in a glider, no power needed. Will it cause you to have a bad day if you lost power?

You can fly a stabilized approach in a glider by using a steeper glide path than max L/D and using spoilers to manage drag to stay on that glide path, but that's not the point under discussion. However, without using the spoilers for drag management, you cannot fly a stabilized approach in a glider unless wind is a constant from TPA to the flare, and that doesn't often happen.

 

[poadeleted20]

Just got back from my lesson. Pulled power back to idle right before turning base, 2nd notch of flaps, turned base, trimmed for 70, called base.

Then final, power still back, last notch of flaps, called final, proper pitch attitude, adjust power as necessary to maintain glide slope.

If you have to pull power to idle before turning base in order to hit your desired final approach speed/altitude/configuration window, you are reaching the base turn too high, too fast, or both. You need to work on managing speed and altitude on downwind so you don't have to go to idle to get down on base.

 

[Henning]

You can fly a stabilized approach in a glider by using a steeper glide path than max L/D and using spoilers to manage drag to stay on that glide path, but that's not the point under discussion. However, without using the spoilers for drag management, you cannot fly a stabilized approach in a glider unless wind is a constant from TPA to the flare, and that doesn't often happen.

It is exactly the point lol. You nailed it exactly. A glider manages a stable approach by adding drag, it has excess energy for the glide path, it is coming in from the front side of the power curve for the approach. The powered plane on an approach that requires it to add 50hp to the kinetic and altitude energy to maintain that target glide slope and make the runway, that is the backside of the curve. If it loses that 50hp input, it can no longer make the runway. When the glider loses its spoiler, it still makes the runway, it just needs to slip off the excess energy. The phrase requires reference, it attaches many places.

 

[MAKG1]

It is exactly the point lol. You nailed it exactly. A glider manages a stable approach by adding drag, it has excess energy for the glide path, it is coming in from the front side of the power curve for the approach. The powered plane on an approach that requires it to add 50hp to the kinetic and altitude energy to maintain that target glide slope and make the runway, that is the backside of the curve. If it loses that 50hp input, it can no longer make the runway. When the glider loses its spoiler, it still makes the runway, it just needs to slip off the excess energy. The phrase requires reference, it attaches many places.

You're right on the dynamics; no one is disagreeing with you there. It's just that being behind the power curve is quite a bit more serious than not being able to make the field if a very unlikely engine failure happens at that particular time.

Being truly behind the power curve means that making only small corrections to one control will push you to a stall. The correct recovery is to apply throttle and push the nose down, both by quite a bit. That's not just turning base too low or too far out. It's being too slow. And this happens with a perfectly working aircraft, that just happens to have been placed too low and slow by the loose nut behind the yoke.

 

[poadeleted20]

It is exactly the point lol. You nailed it exactly. A glider manages a stable approach by adding drag, it has excess energy for the glide path, it is coming in from the front side of the power curve for the approach.

No. Since we're talking about a stabilized approach, we're talking constant airspeed, so it doesn't matter which side of the power curve it's on. Regardless of front or back side, if you add drag while maintaining speed, your descent rate will increase, just as it will for a powered aircraft if you reduce power without changing speed regardless of front or back side of the power curve.

The powered plane on an approach that requires it to add 50hp to the kinetic and altitude energy

You're confusing power with energy to create aerodynamic nonsense. If you're not going to get in the books and learn the terminology and basic theory, I can't teach you via this medium.

:bye:

 

[Johann]

My guess is that the OP's fundamental problem is a lack of understanding of or failure to properly apply the concept of "trim for airspeed, power for vertical speed"

While I understand this, my instructor a lot of times made me "point the nose to the numbers, and maintain the speed at 70 with the power".
70 is best glide so it wasn't behind the power curve.

Do you also teach this?. It confused the hell out of me before solo.

 

[poadeleted20]

While I understand this, my instructor a lot of times made me "point the nose to the numbers, and maintain the speed at 70 with the power".

I don't like that at all, and it's not what the FAA wants us instructors to be teaching since it won't produce a stabilized approach. It might get you to solo faster, but in the long run it's negative training you'll eventually have to overcome, and it's always harder to overcome what you learned early and practiced often.

Do you also teach this?. It confused the hell out of me before solo.

If by "this" you mean "point the nose to the numbers, and maintain the speed at 70 with the power", no, I most certainly do not. I teach trim for speed, then use power to manage descent rate. That normally means loosening the throttle friction, putting your right hand on the throttle, and keeping it there so you can make quick, small throttle movements to keep you on glide path while allowing the trim to move the nose to keep you on trimmed speed while keeping those pitch changes small with your left hand on the yoke/stick (the effect of propwash over the horizontal stab in a single engine airplane being a diverging force on trimmed speed).

 

[Johann]

Actually I think it had the opposite effect and made me take more time to solo because it was really confusing.

Thanks for the explanation!

 

[Hiperbiper]

http://www.youtube.com/watch?v=f6q2VKsvQEQ

"A B-52 pattern refers to a stabilized approach requiring 2 or more counties, and is often seen at pilot mills and student solos."

One of my favorite videos...

 

[CTLSi]

If you have to pull power to idle before turning base in order to hit your desired final approach speed/altitude/configuration window, you are reaching the base turn too high, too fast, or both. You need to work on managing speed and altitude on downwind so you don't have to go to idle to get down on base.

Not true. He wants to maintain 1.3Vso mid base, if he is at idle doing that all the better. On final descend and cross at that speed and the rest should follow. He will have the energy to flare and use his wings as a brake and touch the mains first gently.

Using power on landings should only be needed with a stiff headwind or xwind on final. In calm conditions he needs to be able to land at idle.

 

[poadeleted20]

Not true. He wants to maintain 1.3Vso mid base,

Why on earth would one want to slow that much at that point before extending landing flaps? Depending on the aircraft, that could compromise stall margin in the turn to final.

 

[brian]]

Just got back from my lesson. Pulled power back to idle right before turning base, 2nd notch of flaps, turned base, trimmed for 70, called base.

Then final, power still back, last notch of flaps, called final, proper pitch attitude, adjust power as necessary to maintain glide slope.

Worked out well.

Now just need to smooth out my flare a little.

Getting there!

SWEET!

Let the gurus here fight over terminology. Fact is, you will start to "feel" or "see" it. Just like learning to ride a bike - you gotta just get out and do it... then you will start having real fun

Speaking of which - it's 5PM! Time for me to go fly something

 

[gismo]

If you can't make the runway if the engine quits, you are flying an approach on the back side of the power curve by definition.

Not necessarily although you could end up there if you tried to make the runway with insufficient altitude and speed.

For an example consider flying at the middle of the green ASI arc about 20 feet higher than the runway when you're 5 miles out on final in something draggy like a Great Lakes biplane. At that point you're way into the "front side" of the power curve but there's no way you'd make the runway without power.

 

[Henning]

Not necessarily although you could end up there if you tried to make the runway with insufficient altitude and speed.

For an example consider flying at the middle of the green ASI arc about 20 feet higher than the runway when you're 5 miles out on final in something draggy like a Great Lakes biplane. At that point you're way into the "front side" of the power curve but there's no way you'd make the runway without power.

Right, so as soon as you drop through the required GS plane you transition to the backside and you won't make it unless you get the engine running again.

 

[Silvaire]

...Being truly behind the power curve means that making only small corrections to one control will push you to a stall...

I guess that depends on what you mean by "truly". The backside of the power curve occurs at a specific point and that is a speed at which, if you desire to fly slower than that, then you will have to ADD power.

 

[MAKG1]

I guess that depends on what you mean by "truly". The backside of the power curve occurs at a specific point and that is a speed at which, if you desire to fly slower than that, then you will have to ADD power.

Not really correct without qualification. It works that way if you're trying to maintain a fixed vertical speed, which is indeed the usual scenario. But you can trade airspeed for descent without adding power.

And the transition is rather broad; it's not a "specific" point.

 

[Henning]

Not really correct without qualification. It works that way if you're trying to maintain a fixed vertical speed, which is indeed the usual scenario. But you can trade airspeed for descent without adding power.

And the transition is rather broad; it's not a "specific" point.

Correct, however, the application is the same whether the vertical profile intended is level or sloped. If you cannot maintain it without turning fuel into power, you are behind the curve.

 

[CTLSi]

It is exactly the point lol. You nailed it exactly. A glider manages a stable approach by adding drag, it has excess energy for the glide path, it is coming in from the front side of the power curve for the approach. The powered plane on an approach that requires it to add 50hp to the kinetic and altitude energy to maintain that target glide slope and make the runway, that is the backside of the curve. If it loses that 50hp input, it can no longer make the runway. When the glider loses its spoiler, it still makes the runway, it just needs to slip off the excess energy. The phrase requires reference, it attaches many places.

A powered aircraft has more mass than a glider. Once velocity is achieved, as Newton proves, the aircraft tends to remain in motion.

Combine that with the force of gravity (decent on base/final) and you get the ability to cut power on the numbers or on base and cross the threshold at 1.3 Vso most of the time. Even at idle, the prop will still provide a small amount of thrust, btw.