Pitch. Power. Trim.

[Blackhawk]

The way two teaching techniques that were designed to simplify explaining the pitch/power relationship in flight for new students have become competing gospels with zealous adherents is somehting that I still find somewhat amazing.

And I thought I was the only one.

 

[WApilot]

It's all about trimming for A/S.

 

[azaviator08]

I teach pitch for airspeed, power for altitude. But, I introduce this when starting to work on landings. And I don't use it anywhere else but in the pattern.

 

[mhcasey]

To the OP: If you show up to a lesson with laminated notes on pitch/power/trim, I will tape them to each of your flight instruments just after slapping you in the face. I'll probably laugh about it with friends later. Reread TGrayson's posts and study up on your basic aerodynamics/physics.


Stalls and looking outside: TGrayson, correct me if I'm wrong, but in a power on stall with the ball centered, the airplane will be slipping to the left (assuming clockwise rotating prop), correct? For the same reason a twin with one engine operative will slip in the direction of the inop engine, except that in the single the asymmetric thrust is not as severe?

 

[Approach Control]

Your background in finance will be a handicap as you learn to fly. Engineers can often have the same problems, thinking analog instead of digital.

I’ll keep that in mind and pay attention to my own bias thinking.

As a student pilot, your pitch for straight and level should be using the horizon as the reference. Set the power for cruise to your recommended power setting, pitch the yoke to maintain altitude, trim to relieve your pressure on the yoke and then take a mental picture of what it looks like outside.....

Every reference should be OUTSIDE of the airplane.

Set of the pants handling of the aircraft with visual references as confirmation. I think that is what's being said here.

For most people, learning "seat of the pants" flying builds a better foundation to start with (VFR flying with the Private Pilot certificate). This type of flying stresses all the key points of what is going on with a plane. They can see it and feel it. Then they add in the "by the numbers" method second (with the instrument rating). This increases their precision and deepens their understanding of the intricacies involved. When it's all said and done, skilled pilots use both in equal measure (to fly machines like the jet in your avatar).

Point very well taken. More seat of the pants flying. This method seems to be scoring rather high on this forum, for the private pilot student phase.

Next time your out flying, trim for an airspeed. Then add 300RPM, should give you roughly 300FPM climb and around minus 3-5 kts. Then adjust power for level flight again. Then reduce power by 300 RPM, which should equal 300fpm descent and plus 3-5 knots.

Hence pitch for an airspeed and power for an altitude. And please, keep the rebutal's nice.

Ok, now that logically made sense, but then my "intuition" kicked in and my brain started throwing me yellow caution lights as I read through what you wrote. Help me out here for just a minute: Would this not be a rather difficult task?

First, you say trim for an airspeed. Assuming for a moment that we are just talking about basic climbs and descents (no turning climbs or turning descents), won't this be rather difficult to accomplish with higher airspeeds, given the aerodynamic forces on the trim-controls? At lower airspeeds, won't the trim-control force required to move the surfaces be significantly smaller and at higher airspeeds, significantly larger?

And, won't that gradient of trim-control force required as you move from high airspeeds to lower airspeeds, cause problems with "handling consistency" in maneuvering the aircraft with precision most of the time? I'm just trying to think this all the way through. Certainly, something I could test, with an IP in the right seat, no doubt.

The trim for airspeed, power for altitude technique you described works fine. A person just needs to understand there are equally acceptable ways of thinking about it and doing it.

Are they still equal and acceptable if the force required to trim-to a particular airspeed is greater at higher airspeeds?

Example 1: I trim to 105 kts from 85 kts in a 172, then POWER to a 300 fpm climb by adding 300 bars on the tac according to Mshunter.

Example 2: I trim to 350 kts from 250 kts in jet, then POWER to a 3,000 fpm climb by adding the equivalent shaft rpm to the turbines according to Mshunter.

First, how can you trim to 105 and 350 from 85 and 250 respectively, without trimming down the nose to build-up airspeed? Then, turn right around and put-on more power [either bars or shaft] to establish a rate of descent. Does this mean that the aircraft goes down first in order to go up?

What about the inverse. First, I trim-up the nose to reduce speed from 105 and 350 down to 85 and 250 respectively. Then, I take-off some power [either bars or shaft] to establish a rate of descent. Does this mean that the aircraft goes up first in order to go down?

Clearly pitch and power are two terms in the energy managment equation. Depending on the result you are looking for drives how you make adjustments.

Precisely why I made this thread.

You had an experience with your student where Pitch/Power/Trim [or, just Power in your case] could have produced a different outcome. If that same student came over the numbers too steep, then what would the effect of adding Power -vs- Pitching up have been? Would the aircraft have floated down the runway, then?

This is a great example of why I made this thread. Why did that student feel the need to add more manifold pressure as the solution for arresting what he perceived as being a sink rate that was, too high?

I find this issue of Pitch/Power/Trim, not to be all that "easy" in every circumstance. That's why I'm trying to get more clarity on the subject. When I read Proficient Pilot [Barry Schiff] on this subject, some of what he says seems rather counter intuitive and very dependent upon the situation and what the pilot needs the aircraft to do, at any given time.

...In steady state flight, AOA always controls airspeed (not pitch).

How do you increase/decrease your AOA without also increasing/decreasing Pitch attitude at the same time? [conventional fixed-wing aircraft]

Rate of climb, in steady state flight, depends on excess power, or excess thrust for angle of climb. You can achieve excess power (or thrust) through throttle movements, or by changing your airspeed through AOA changes.

If I maintain "n" EPRs [where, "n" equals some EPR value] and increase/decrease AOA, how does that at the same time increase/decrease power or thrust, as opposed to increasing/decreasing airspeed only?

Throttle never controls airspeed in steady state flight.

If my aircraft is in uncelebrated flight with no pitch, no roll and no yawing moment and I push-up the EPR on both engines, why won't my airspeed increase, if my AOA remains the same?

...Reversing the function of these controls will generally work on the front side of the power curve, but not on the backside. If you get low and slow on short final, thinking of the yoke as the "up" control is a real problem.

Ok, I think I understand that part.

First, do everything you can as a pilot not to get behind the power-curve. However, if you do find your aircraft behind the power-curve, think of the "throttle" as the Pitch control mechanism and the yoke/stick as the "speed" control mechanism [or, the power control].

Yes/No?

So, to get back to MNflyguy’s student, who came in over the numbers with a sink rate that was too fast, you [tgrayson] are saying that MNflyguy’s student should have applied more power. So, as I read what you are saying, the student was correct? But, if you look at what MNflyguy said, the student ended up landing well beyond the numbers. So, is it safe to say that the student made the right decision, but that by doing so, the student shortened the runway and thus the effective landing distance was reduced for this particular landing? Again, trying to understand.

For descents - (prior to descent plane is level, trimmed out for hands free flying at a given power setting).

1. Reduce power until desired descent rate established (still hands free).
2. Power is restored to previous trimmed power setting. (Roughly 50 ft before desired altitude)
3. You do nothing as the nose comes up by itself, and airplane is still trimmed out and you are still hands free in level flight.

A good demonstration makes students realize they don't have to work so hard.

*In all of my dual given, I don't think I have ever said, "Pitch, Power, Trim".

Very interesting, indeed. Does anyone here disagree with this in anyway. Or, have any modification to it?

It seems so simple and so straight forward. However, you covered the descent from unaccelerated straight/level flight. You did not however, cover the climb from unaccelerated straight/level flight. Is it therefore correct to apply the same principle to initiate the climb?

Example: Increase throttle [from hands-off unaccelerated straight/level flight], nose rises [aerodynamic properties of the aircraft], climb to desired altitude, decrease throttle to level off, fly on to your next decision. Do I have that about right?

To the OP: If you show up to a lesson with laminated notes on pitch/power/trim, I will tape them to each of your flight instruments just after slapping you in the face. I'll probably laugh about it with friends later.

JKD teaches me [among many other things] to "intercept" my adversary's strike and embed my own unique offensive strike within the "interception" itself.

The best defense is a good offense and the best offense, is the one your adversary cannot detect until it is too late. Civilian IP’s who play that game probably don’t remain in vogue for very long. Raising your hand, would be the biggest mistake of your life.

Guys, can we please stay civil in this thread – I truly appreciate all the help and insight here, but I fail to see why getting one’s self in a wrist breaking inner-lock is tantamount to teaching a student how to control his aircraft. But, I digress…

Thanks guys! All of you! Even my wrist-lock candidate!

It appears as though this thread has stuck a nerve within the IP community and that is a GOOD thing, not a bad thing. It is ok to disagree without becoming violently disagreeable. Many here tend to be leaning toward the initial phases of flight instruction being done at the SOTP level [seat of the pants]. That seems to be what I take away from this thread.

There is no question that I’m moving towards a single-pilot certified jet and I don’t want to carry any bad habits into that level of flying. Piloting covers many subjects and this is just one of the embedded subjects. Pitch/Power/Trim seems to develop some controversy among some, but my goal is to be efficient and optimize everything I do. That’s why I bring it up and that’s why I seek your opinions. There is a ton of myth, rumor, speculation and innuendo out there when it comes to what an aircraft will or won’t do, can or can’t do. That’s why I need to make sure that I’m always dealing in the reality of flying, not the hype.

a) Most of you would prefer to see your student get good at SOTP flying, first.

b) Most of you would prefer to see your students head outside the cockpit, not hung-up on instruments.

c) Most of you would prefer to see your students get familiar with making control inputs and then observing what effect those inputs had on the flight attitude of the aircraft, as opposed to relying on placing needles on numbers or dashes on lines of an instrument gauge, first.

d) Some of you enjoy slapping your students across the face, if they come up with something creative that they think might help them learn better, even if it means that you get put into an unbreakable inner wrist-lock and the distinct possibility of losing your wrist.

e) All of you are cream of the crop for putting up with my questions!

Thanks.

[I’ll standby for any specific replies from my above questions – if you deem it necessary]

 

[mhcasey]

Holy geeze that is the longest post I've ever seen. I'll just reply to my part.

JKD teaches me [among many other things] to "intercept" my adversary's strike and embed my own unique offensive strike within the "interception" itself.

The best defense is a good offense and the best offense, is the one your adversary cannot detect until it is too late. Civilian IP’s who play that game probably don’t remain in vogue for very long. Raising your hand, would be the biggest mistake of your life.

Guys, can we please stay civil in this thread – I truly appreciate all the help and insight here, but I fail to see why getting one’s self in a wrist breaking inner-lock is tantamount to teaching a student how to control his aircraft. But, I digress…

I have no idea what transpired there. JKD? Embedding unique offensive strikes? Adversaries? Am I an adversary?

I was making a joke and a point - not trying to hurt feelings. You will crash into something or someone one day if you're squirming around in the cockpit looking for your "pitch/power/trim" card on final. My point was that they're worthless and you need to look outside and feel the airplane if you want to be a decent pilot. I've only flown small birds, but I've never been in a single cockpit with marked "trip settings," so I'm really not even sure why you're so worried about it. Are you going to keep track of your spins from the reference line all flight?

My anticipated response: "Ah yes...fly by the pants with a hint of sarcasm approach! Outstanding!" I feel like I'm watching a Geico commercial...

Are you military or civilian? Civilian "IPs" are called CFIs.

Final advice: Read Illustrated Guide to Aerodynamics and everything in the Tech Talk forum. I really think you will be well off to learn some basic aerodynamics before you take this thread in 90 different directions to answer all of your questions.

 

[Blackhawk]

Look, don't overanylize it all. In the words of that famous pilot Ty Webb, "There is a force in the universe that makes things happen...and all you have to do is get in touch with it. Stop thinking...let things happen.... and Be the airplane. Be, the airplane."

 

[tgrayson]

The way two teaching techniques that were designed to simplify explaining the pitch/power relationship in flight for new students have become competing gospels with zealous adherents is somehting that I still find somewhat amazing.

It's not a teaching technique, it's an explanation of physics. And if it appears to be zealotry, it's because nature is a zealot. I'm always a bit pizzled when I see the liberal arts community call the scientific community "arrogant" and "opinionated". Darn right they are, because they have the only certain knowledge that exists in the world.

 

[tgrayson]

correct me if I'm wrong, but in a power on stall with the ball centered, the airplane will be slipping to the left (assuming clockwise rotating prop), correct? For the same reason a twin with one engine operative will slip in the direction of the inop engine, except that in the single the asymmetric thrust is not as severe?

Yes. That's why when one wing drops first, it's usually the right one. Leaving the ball slightly out of center can produce a nice straight stall. Possibly a slight bank might work, too, but I have tried that.

 

[tgrayson]

How do you increase/decrease your AOA without also increasing/decreasing Pitch attitude at the same time? [conventional fixed-wing aircraft]

Generally, you can't. Your pitch attitude is *defined* to be your climb angle plus your AOA. So, in a relative sense, pitch is somewhat of a stand-in for AOA, meaning that raising your nose above where it currently is will represent an increase in AOA.

But not always. If you stall the aircraft in level flight, you may see your pitch drop, yet your AOA is very high. That's the problem with these rules of thumb...they tend to fail at the edges.

If my aircraft is in uncelebrated flight with no pitch, no roll and no yawing moment and I push-up the EPR on both engines, why won't my airspeed increase, if my AOA remains the same?

It can't, other than a brief fluctuation. Why? Consider that your lift is proportional to your AOA and airspeed. In unaccelerated flight, it equals the weight of the airplane. What happens if you increase airspeed at the same AOA? Lift increases and you start to pull a load factor. The aircraft arcs upwards until the flight path is inclined with respect to the horizon and you now have a component of gravity that slows the airplane back down. You have now established yourself in a climb at your original airspeed.

If I maintain "n" EPRs [where, "n" equals some EPR value] and increase/decrease AOA, how does that at the same time increase/decrease power or thrust, as opposed to increasing/decreasing airspeed only?

It doesn't. It changes the amount of power or thrust required for your present flight path. For instance, you can increase your bank account by increasing your income (thrust) or reducing your expenses (thrust required).

First, do everything you can as a pilot not to get behind the power-curve. However, if you do find your aircraft behind the power-curve, think of the "throttle" as the Pitch control mechanism and the yoke/stick as the "speed" control mechanism [or, the power control]. Yes/No?

Absolutely. And the easiest way to do this is to always think of the yoke as your speed control. Mental habits.

So, to get back to MNflyguy’s student, who came in over the numbers with a sink rate that was too fast, you [tgrayson] are saying that MNflyguy’s student should have applied more power.

First, realize that I have been discussing unaccelerated flight. This does not address the concept of zooming, which is the rapid conversion of kinetic energy into potential energy. If I just haul back on the yoke in level flight, I'll get one heck of a climb out of the airplane and can even end up going straight up, with a zero airspeed, or maybe even looping.

The landing flare is sort of like a mini zoom, whereby your descent rate is controlled by the rate at which you convert kinetic energy into potential energy. As long as you have adequate potential energy, you don't need to add any more energy to the airplane (via power). Yes, if you get too slow, then you have no lift reserve that can be used to convert your kinetic energy and you'll need to add power.

 

[MNFlyGuy]

Let me answer the question you asked about my student. How steep the approach is alone would not dictate if power would be added or not. In your sceniro we are over the numbers, assuming we are in a position (altitude and descent rate) that a normal landing could be made we do just that. Round out, flare and land. Using our pitch to control airspeed during this time. If the sink rate was too high, power should be added.

Your instructor should put you in a number of positions on final approch for you to make adjustments and decisions to continue the approach or not. High, low, fast, slow on center line and not. As you experiance these combinations with your instructor you will learn what adjustments to make when. Try not to overthink it.

 

[MidlifeFlyer]

It's not a teaching technique, it's an explanation of physics. And if it appears to be zealotry, it's because nature is a zealot.

I have yet to see the NTSB report where the cause of the accident was having learned one way or the other.

I know. When you look at the accident, you will be absolutely certain that it had to have been one way and not the other. I've had that conversation before when I described a wind shear event I was involved in. Someone tried their best to convince me that I didn't fly it the way I flew it.

I don't find scientists particularly arrogant. Certainly not more than anyone else. But flying requires the application of motor skills to aerodynamics and, since both explanations ultimately result in the same inputs, the best way to explain it is the way it's best understood by both instructor and student.

btw, I've heard people well-versed in physics argue with each other vehemently on this nonsensical issue. Scientist are hardly immune from beliefs that overcome logic.

 

[Approach Control]

But not always. If you stall the aircraft in level flight, you may see your pitch drop, yet your AOA is very high.

Light bulb moment, thanks.

Why? Consider that your lift is proportional to your AOA and airspeed. In unaccelerated flight, it equals the weight of the airplane. What happens if you increase airspeed at the same AOA? Lift increases and you start to pull a load factor.

Another light bulb moment. Of course, push-up the throttle, increase the airflow over the the wings; lift increases. Beautiful.

The aircraft arcs upwards until the flight path is inclined with respect to the horizon and you now have a component of gravity that slows the airplane back down. You have now established yourself in a climb at your original airspeed.

A third light bulb moment in a row. It all makes sense. Aircraft climbs until its new lift load is balanced with gravity given its new [higher] airspeed. Again, beautiful.

It doesn't. It changes the amount of power or thrust required for your present flight path. For instance, you can increase your bank account by increasing your income (thrust) or reducing your expenses (thrust required).

LOL! Yep. Good example. Nice work.

First, realize that I have been discussing unaccelerated flight. This does not address the concept of zooming, which is the rapid conversion of kinetic energy into potential energy.

Ok, now you are speaking my language: Kinetic/Potential transformations.

If I just haul back on the yoke in level flight, I'll get one heck of a climb out of the airplane and can even end up going straight up, with a zero airspeed, or maybe even looping.

Various transformations of KE to PE [in the case of the loop over the top].

The landing flare is sort of like a mini zoom, whereby your descent rate is controlled by the rate at which you convert kinetic energy into potential energy.

Well, since you put it like that! All one has to do is find the KE/PE ratio that lends itself to the smooth transition from known sink rate, to desired touchdown point [location].

As long as you have adequate potential energy, you don't need to add any more energy to the airplane (via power).

Love it! Easy.

Yes, if you get too slow, then you have no lift reserve that can be used to convert your kinetic energy and you'll need to add power.

Perfect.

Very easily understood. The basic language of physics helped me to visualize what you were saying and put it into a mental picture. I need that mental picture. Thank you.

You should move out to Califorinia, or I should move out to TN. (lol)

 

[ppragman]

Pitch for pitch, power for power, trim for trim.

It all depends on what you want to do.

There is no black and white answer for what to do. Trim settings, power settins, and pitch settings will vary wildly with loading, aircraft specifics, and what you're trying to do (e.g. landing vs. takeoff vs. holding etc.). If you're in the 207 and you're not dynamically working trim and power you'll be so far behind the airplane you'll be in some serious trouble. There are some aircraft specific things that can trend towards regularity (e.g. takeoff elevator and rudder trim settings) but those are exceptions to the rule rather than the rule. Flying is a dynamic environment, and while a 172 may be fairly predictable in trim settings when Center of Gravity locations are remaining more or less constant, many airplanes are not so easy to predict.

Example? Well, in the 207 when you have the C.G. loaded to the aft limit the nose down trim required for takeoff tends to be much much closer to the stop. In fact, with flaps 10 and a legal aft limit C.G. for takeoff, you may still run out of trim. Be proactive yes, but recognize that you must be able to adjust.

 

[MNFlyGuy]

btw, I've heard people well-versed in physics argue with each other vehemently on this nonsensical issue. Scientist are hardly immune from beliefs that overcome logic.

You should hear me get going about "centrifigual force" and the forces on a turning airplane. But I will save that for another thread sometime!

 

[tgrayson]

I have yet to see the NTSB report where the cause of the accident was having learned one way or the other.

How they learned is immaterial; what's important is their understanding. And the accident records are full of accidents where people got behind the power curve and mushed the airplane into the ground, or stalled it trying to stretch a glide. These are all errors of understanding. Whether the level of understanding is correlated with their instruction, I do not know, but if instruction has any value whatsoever, then I think the correlation exists.

since both explanations ultimately result in the same inputs

No, they don't.

You get low and slow on final, and the person who thinks the yoke controls altitude will mush the airplane into the ground, or stall it. You've got to *push* in that scenario and that's hard for many pilots to understand.

btw, I've heard people well-versed in physics argue with each other vehemently on this nonsensical issue.

To be precise, knowing physics isn't knowing aerodynamics. You won't hear aeronautical engineers debate this subject any more than you will hear biologists debate whether evolution occurred or hear astrophysicists debate whether the big bang occurred, or geologists debate whether the continents move. Those concepts are fundamental to those disciplines as this one is to ours. There is no debate about this among those with the slightest formal education in the subject. The debate occurs among those who think their intuitions are a sufficient source of information, rather than digesting existing knowledge.

 

[CoffeeIcePapers]

I have to LOL at the JKD standing wrist lock. Good luck against a resisting opponent. I prefer a Seoinage, Harai Goshi, or Kosoto Gari after closing the distance.

That is my contribution to the thread.

 

[Approach Control]

... Round out, flare and land.

Does:

Round out = apply back pressure on stick/yoke = progressive transformations of KE into PE in a smooth linear motion.

Flare = peak of back pressure on stick/yoke = peak of KE to PE transformation process to near stall speed.

Land = aerodynamic stall = KE/PE ratio is zero.

Would that be correct. Or, am I missing something, here?

Your instructor should put you in a number of positions on final approch for you to make adjustments and decisions to continue the approach or not..... Try not to overthink it.

Thanks, I won't and that's the point to all of this. To obtain a framework within which I can place things, so that I don't have to over-think them all the time.

I just need a good mental picture/framework from which to know what "good/correct/appropriate" should look like. That picture will help me to not over-think things too much. I want to be competent, but not schizoid or paranoid about flying because I lack a strong grounding in the fundamentals.

 

[tgrayson]

KE/PE ratio is zero.

Not possible, unless you have a stall speed of zero. But PE will be zero and that makes the ratio undefined.

The limit, of course, as PE trends toward zero will be infinity.

 

[Blackhawk]

Consider that your lift is proportional to your AOA and airspeed.

Really??? Which aerodynamics book did you read this in??? Lift is proportional to Cl and airspeed, not AOA and airspeed. I know it seems convenient to simplify things by equating an increase in lift to an increase in AOA, but you do a dis-service to teaching someone if you teach them something that is not true. I have had more than one CFI applicant spout this nonsense due to the law of primacy.