Pitch controls altitude. Power controls airspeed?
Hope no newbie reads this....you guys are gonna get someone killed.
C152 flaps down and speed decaying and threshold rising in screen. AND you guys want to pull back to go up and power to maintain speed???? Have you forgotten what happens next?
Interesting. DHC4 with all the laundry out doing classic wheel barrow routine. Power increases and Caribou does what?
A lightie should be flown like a lightie. Do not understand the reason for imitating a heavy. I suppose I will learn this whilst trying to master an ILS for my CIR.
C152 flaps down and speed decaying and threshold rising in screen. AND you guys want to pull back to go up and power to maintain speed???? Have you forgotten what happens next?
Interesting. DHC4 with all the laundry out doing classic wheel barrow routine. Power increases and Caribou does what?
A lightie should be flown like a lightie. Do not understand the reason for imitating a heavy. I suppose I will learn this whilst trying to master an ILS for my CIR.
Last edited by OZBUSDRIVER; 8th Jul 2005 at 12:05.
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I have to disagree with you OZBUSDRIVER. I think you will find that while trying to master your ILS you'll find it easier to control your glideslope (ROD) by selecting and maintaining specific powers, which leaves you only one way to control IAS. It's not a case of lighties imitating heavies, I think it's just the best way to fly the aeroplane.
My general philosophy on the original question is that pitch is the most powerful flight control, so it (generally) is used to control the performance you are most concerned about. There are exceptions, and at the end of the day you still need the old "string around the back of your neck", but it is something I find helps in coming to terms with the concept.
It's really as Arm out the window says...
Bottom line: "It depends" :-)
My general philosophy on the original question is that pitch is the most powerful flight control, so it (generally) is used to control the performance you are most concerned about. There are exceptions, and at the end of the day you still need the old "string around the back of your neck", but it is something I find helps in coming to terms with the concept.
It's really as Arm out the window says...
Bottom line: "It depends" :-)
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Primary effect of elevator - Change in pitch and flightpath.
Secondary effect - you will get a change in airspeed.
Primary Effect of adding power/thrust - Change in speed.
Secondary effect - You will get a change in flightpath.
Why - o - why would you start controlling the aircraft with the secondary effects during the approach????
That's what the primary effects are for!!!! The secondary effects are a consideration (and sure,... with some more experience under your belt a combination of the two is possible.)
Pitch for path. Power for speed. Will work in a C152 OZBUSDRIVER!! Push the power in to add speed, pull the nose up to climb (with full flaps!). I know.. I've done it. This rubbish about immitating a heavy.... An aeroplane's an aeroplane. Big, small, fast, slow, heavy, light. They all work the same.
Pitch for path. Power for speed. They are the Primary effects!
Will work in a C152
Will work in a jumbo
and will work in every fixedwing aircraft in between.
Secondary effect - you will get a change in airspeed.
Primary Effect of adding power/thrust - Change in speed.
Secondary effect - You will get a change in flightpath.
Why - o - why would you start controlling the aircraft with the secondary effects during the approach????
That's what the primary effects are for!!!! The secondary effects are a consideration (and sure,... with some more experience under your belt a combination of the two is possible.)
Pitch for path. Power for speed. Will work in a C152 OZBUSDRIVER!! Push the power in to add speed, pull the nose up to climb (with full flaps!). I know.. I've done it. This rubbish about immitating a heavy.... An aeroplane's an aeroplane. Big, small, fast, slow, heavy, light. They all work the same.
Pitch for path. Power for speed. They are the Primary effects!
Will work in a C152
Will work in a jumbo
and will work in every fixedwing aircraft in between.
Bottums Up
Thank the deity Ibol, some common sense.
Mamakim
You said,
Why oh why do you want to subscribe to a belief that changes between base & final? If you stick with Ibol's, power for airspeed & pith for flight path, the belief is a constant through all regimes of flight.
Mamakim
You said,
But I was always told by my instructor that power controls height when on base and that power controls airspeed when on finals and I find that that mindset generally works although its often that I adjusting and fine tuning both all the time.
But with the greatest respect cc, is it that simple?
One of the many complicating factors here, as I mentioned above, is the design of the aircraft. In particular, the interaction of the thrust/drag couple with the lift/weight couple (which is a function of aircraft design) has an impact on the primary effect of thrust.
My understanding is that many training aircraft are deliberately designed so that the interaction between the two couples has the following effects, among others:
First, if power is reduced and no other control is touched, the aircraft automatically pitches down to maintain about the same airspeed and, consequently, the aircraft will begin to descend;
Secondly, the reverse applies – if power is increased and no other control is touched, the aircraft automatically pitches up to maintain about the same airspeed and, consequently, the aircraft will begin to climb.
Thus, in aircraft designed this way, and usually at circuit/approach speeds in particular, it’s not just a case of “add power to get more speed”. If power is added on its own, the aircraft maintains about the same speed and begins to climb, and vice versa. To make it go faster, you have to push or trim nose down, and vice versa.
One of the many complicating factors here, as I mentioned above, is the design of the aircraft. In particular, the interaction of the thrust/drag couple with the lift/weight couple (which is a function of aircraft design) has an impact on the primary effect of thrust.
My understanding is that many training aircraft are deliberately designed so that the interaction between the two couples has the following effects, among others:
First, if power is reduced and no other control is touched, the aircraft automatically pitches down to maintain about the same airspeed and, consequently, the aircraft will begin to descend;
Secondly, the reverse applies – if power is increased and no other control is touched, the aircraft automatically pitches up to maintain about the same airspeed and, consequently, the aircraft will begin to climb.
Thus, in aircraft designed this way, and usually at circuit/approach speeds in particular, it’s not just a case of “add power to get more speed”. If power is added on its own, the aircraft maintains about the same speed and begins to climb, and vice versa. To make it go faster, you have to push or trim nose down, and vice versa.
Last edited by Creampuff; 9th Jul 2005 at 22:31.
Come on you blokes, stop clouding the issue for the poor learners!
There are numerous factors influencing what happens when we fly, but what they need are good ways of organising themselves to get the performance they want.
May I humbly suggest that for a starter (and depending on what you fly and what weight and conditions you're at, but a learner will generally be in a training machine at training weights), we use Power + Attitude = Performance.
Therefore, depending on the phase of flight you're in, set an appropriate power and attitude, trim, look out the front and let it all stabilise.
Next, note performance; is it what you want? Yes / No.
If yes, good.
If no, make a change depending on what's not right (and here's where opinions may differ, but it's all the same result really) -
For example - in a climb, too slow, already at climb power, so we must lower the attitude a bit to speed up.
Or: In a cruise S&L, too slow. We must add power to speed up, but ALSO lower the attitude as the speed increases so we don't climb.
Two situations, both need increased speed, but we use different control inputs to achieve our aim, because we're pilots and we have enough brains to pick the right thing to do in a given circumstance!
Saying that there's only one valid control technique is pointless; as I said before, we just need a way of thinking that works for us.
However, awareness of attitude is a very good thing because it tends to reduce overcontrolling and keeps you looking out the front - a fine habit to develop.
There are numerous factors influencing what happens when we fly, but what they need are good ways of organising themselves to get the performance they want.
May I humbly suggest that for a starter (and depending on what you fly and what weight and conditions you're at, but a learner will generally be in a training machine at training weights), we use Power + Attitude = Performance.
Therefore, depending on the phase of flight you're in, set an appropriate power and attitude, trim, look out the front and let it all stabilise.
Next, note performance; is it what you want? Yes / No.
If yes, good.
If no, make a change depending on what's not right (and here's where opinions may differ, but it's all the same result really) -
For example - in a climb, too slow, already at climb power, so we must lower the attitude a bit to speed up.
Or: In a cruise S&L, too slow. We must add power to speed up, but ALSO lower the attitude as the speed increases so we don't climb.
Two situations, both need increased speed, but we use different control inputs to achieve our aim, because we're pilots and we have enough brains to pick the right thing to do in a given circumstance!
Saying that there's only one valid control technique is pointless; as I said before, we just need a way of thinking that works for us.
However, awareness of attitude is a very good thing because it tends to reduce overcontrolling and keeps you looking out the front - a fine habit to develop.
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Go back to the formula
Arm out of the window has the closest answer to which, IMHO is correct... a combination of both is required and is dependent on what flight regime you are in (as well as what aircraft you are in).
I was taught that on finals: Attitude for IAS, Power for ROD... That way you can 'ride the rails' on your final approach and make your aim point. (Aimpoint, Aspect Airspeed... Aimpoint, Aspect Airspeed.)
Some like it, others don't.
Just remember this from the formula for Lift:
Lift = Coefficient of Lift x 1/2 rho x velocity squared x wing surface area
So if you increase velocity, then CL or something else has to be reduced so that you don't increase lift and begin to climb. Solution, change the angle of attack of the wing to the relative airflow by changing the aircraft's attitude thereby changing CL
Answer: If you change speed (+/-), you must change CL by changing attitude (+/-) to maintain the same amount of lift (unless you can change air density [unlikely] or the wing's surface area [flaps, etc.])
That's my two cents worth, and it may be worth only two cents.
What WILL happen is that one day it will seem natural which sticks to push and pull to make the aircraft do what you want it to and you won't even think about it. (I'm still waiting for that day to arrive for me. ;-)
Safe Flying
CB
I was taught that on finals: Attitude for IAS, Power for ROD... That way you can 'ride the rails' on your final approach and make your aim point. (Aimpoint, Aspect Airspeed... Aimpoint, Aspect Airspeed.)
Some like it, others don't.
Just remember this from the formula for Lift:
Lift = Coefficient of Lift x 1/2 rho x velocity squared x wing surface area
So if you increase velocity, then CL or something else has to be reduced so that you don't increase lift and begin to climb. Solution, change the angle of attack of the wing to the relative airflow by changing the aircraft's attitude thereby changing CL
Answer: If you change speed (+/-), you must change CL by changing attitude (+/-) to maintain the same amount of lift (unless you can change air density [unlikely] or the wing's surface area [flaps, etc.])
That's my two cents worth, and it may be worth only two cents.
What WILL happen is that one day it will seem natural which sticks to push and pull to make the aircraft do what you want it to and you won't even think about it. (I'm still waiting for that day to arrive for me. ;-)
Safe Flying
CB
The RULES...
I'm surprised no one's mentioned the rules:
RULE #1 - Power + Attitude (+ Configuration) = Performance
Got that?!
Ohhhhh hang on
that's Rule #2.
Rule #1 - ALWAYS LOOK COOL!!!!
CR.
RULE #1 - Power + Attitude (+ Configuration) = Performance
Got that?!
Ohhhhh hang on
that's Rule #2.Rule #1 - ALWAYS LOOK COOL!!!!
CR.
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A lot of wise words have been said in this topic, but in IMHO the most important lesson is to abide by the laws of physics which ACTUALLY DO take into account the aerodynamic properties of the aircraft in question. You do not fly a propeller driven aircraft the same way you fly a jet powered aircraft. A propeller driven aircraft is typically very speed stable (as demonstrated during Attitude - Power - Trim exercises early during eberyones flying training) and it works very well indeed to trim the aircraft out for the desired speed while on G/S and use power changes to control the desired trajectory, ie the glideslope. In a jet - that is not the case, as you are on the back side of the power curve and typically unstable in speed.
To quote the classic BOEING compendium "Swept Wing Jet Characteristics":
Basic Rule No. 2:
Control airspeed with the throttles when thrust is variable. (Variable thrust - fixed flight path). Example Terminal area / approach / Holding Pattern / Slow Flight.
Basic Rule No. 3:
Control airspeed with yoke or pitch control when thrust is NOT a variable ( Fixed thrust - variable path)
Example Climb / Descent with idle thrust / Normal or high speed Emergency maneuvers (Engine out situations etc.)
Everyone do of course know what Basic Rule Rule Number 1 is, but as I always make an effort to complete the things I begin I sha
To quote the classic BOEING compendium "Swept Wing Jet Characteristics":
Basic Rule No. 2:
Control airspeed with the throttles when thrust is variable. (Variable thrust - fixed flight path). Example Terminal area / approach / Holding Pattern / Slow Flight.
Basic Rule No. 3:
Control airspeed with yoke or pitch control when thrust is NOT a variable ( Fixed thrust - variable path)
Example Climb / Descent with idle thrust / Normal or high speed Emergency maneuvers (Engine out situations etc.)
Everyone do of course know what Basic Rule Rule Number 1 is, but as I always make an effort to complete the things I begin I sha
Last edited by waav8r; 11th Jul 2005 at 12:02.
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You just get the speed right any way you can and keep the aiming point fixed in the windscreen. Both power and attitude control both speed and rate of descent. How can you say one control input only has one effect?
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I read an article in some flying mag years ago that basically explained how the idea of PITCH controling AIRSPEED was a bad habit introduced to the civil world after WW2 by inexperienced and (sometimes) poorly trained fighter pilot's.
A low hour pilot flying a mustang (for example) with a high speed, low drag, laminar flow wing would find that lowering the nose would result in a rapid increase of speed for a reatively small, or no appreciable, increase in ROD.
David Davies does a good job of explaining what happens if you try this in a large jet transport. You get (initially) a massive increase in ROD with a relatively small increase in speed.
A low hour pilot flying a mustang (for example) with a high speed, low drag, laminar flow wing would find that lowering the nose would result in a rapid increase of speed for a reatively small, or no appreciable, increase in ROD.
David Davies does a good job of explaining what happens if you try this in a large jet transport. You get (initially) a massive increase in ROD with a relatively small increase in speed.
From Aerodynamics for Naval Aviators pp 350-352 by H. H. Hurt, Jr. University of Southern California, published by U.S. Navy 1960, revised 1965:
[Italics and capitals in original text.]
For the conditions of steady flight with a given airplane, each angle of attack corresponds to a specific airspeed. Each angle of attack produces a specific value of [lift coefficient] and each value of [lift coefficient] requires a specific value of equivalent airspeed to provide lift equal to weight. Hence, angle of attack is the primary control of airspeed in steady flight.
Primary control of airspeed in steady flight by angle of attack is an important principle. …
[T]he rate of climb in steady flight is a direct function of the difference between power available and power required. … For this reason, it is apparent that power setting is the primary control of altitude in steady flight. …
FLYING TECHNIQUE. Since the conditions of steady flight predominate during a majority of all flying, the fundamentals of flying technique are the fundamentals of steady flight:
(1) Angle of attack is the primary control of airspeed.
(2) Power setting is the primary control of altitude, i.e., rate of climb/descent.
With the exception of the transient conditions of flight which occur during maneuvers and acrobatics, the conditions of steady flight will be applicable during such steady flight conditions as cruise, climb, descent, takeoff, approach, landing etc. A clear understanding of these two principles will develop good, safe flying techniques applicable to any sort of aeroplane.
Primary control of airspeed in steady flight by angle of attack is an important principle. …
[T]he rate of climb in steady flight is a direct function of the difference between power available and power required. … For this reason, it is apparent that power setting is the primary control of altitude in steady flight. …
FLYING TECHNIQUE. Since the conditions of steady flight predominate during a majority of all flying, the fundamentals of flying technique are the fundamentals of steady flight:
(1) Angle of attack is the primary control of airspeed.
(2) Power setting is the primary control of altitude, i.e., rate of climb/descent.
With the exception of the transient conditions of flight which occur during maneuvers and acrobatics, the conditions of steady flight will be applicable during such steady flight conditions as cruise, climb, descent, takeoff, approach, landing etc. A clear understanding of these two principles will develop good, safe flying techniques applicable to any sort of aeroplane.
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From Handling The Big Jets
In a very slow approach to a stall the incidence can be controlled very accurately, and in this steady slow approach condition, from an initial trimmed- out steady state descent, incidence bears a fixed relationship to airspeed. But only under these strictly defined conditions. If anything at all should disturb the flight path then the assumed relationship between airspeed and incidence is lost.
Ibol, are you trying to get someone killed?
Ever heard of Coffin Corner? Little Sunfish and his instructor went there in a Cessna 150 one day and only just got out.
Jets and light aircraft fly by the same laws, but the "coefficients" are very very different. Light aircraft land relatively fast with no power. Heavies land relatively slow with more power.
In landing a light aircraft, control your speed by pitch attitude and use the throttle to maintain your flight path as you are taught. It's easier that way because the speed will respond quicker to pitch changes than to engine speed changes.
When you get to do short field stuff with full flaps, you are operating more like a heavy (closer to coffin corner) and you will need power to maintain your speed and find yourself adjusting attitude to get exactly on aimpoint.
My limited understanding of Heavy jets is that you are always landing much further down (or is it up?) the lift drag curve(in other words more drag and higher power) than light aircraft for two reasons.
1. To keep landing speeds reasonable.
2. To deliberately keep more power on since jets don't spool up instantaneaously, and you may need that power to go around.
OK all you experts, tear me to shreds.
Ever heard of Coffin Corner? Little Sunfish and his instructor went there in a Cessna 150 one day and only just got out.
Jets and light aircraft fly by the same laws, but the "coefficients" are very very different. Light aircraft land relatively fast with no power. Heavies land relatively slow with more power.
In landing a light aircraft, control your speed by pitch attitude and use the throttle to maintain your flight path as you are taught. It's easier that way because the speed will respond quicker to pitch changes than to engine speed changes.
When you get to do short field stuff with full flaps, you are operating more like a heavy (closer to coffin corner) and you will need power to maintain your speed and find yourself adjusting attitude to get exactly on aimpoint.
My limited understanding of Heavy jets is that you are always landing much further down (or is it up?) the lift drag curve(in other words more drag and higher power) than light aircraft for two reasons.
1. To keep landing speeds reasonable.
2. To deliberately keep more power on since jets don't spool up instantaneaously, and you may need that power to go around.
OK all you experts, tear me to shreds.
Bottums Up
Sunfish,
Coffin corner doesn't apply to C150 et al. It's where, due to compressability, the Vmo and Vs meet.
Most lighties can't get high enough or fast enough when high to have the problem.
You said,
I was taught the same but 2 years later, by the time I became an instructor at the very same flying school, under a different CFI & HoT, I was directed to teach attitude for aim point, power for speed. (which at the time I thought was horse sh!t, because of course I was a grade three instructor and what did these ex military Grade 1 jocks know?? 
, more importantly, it was contrary to what I was taught and what I knew!!!!!!)
So having learned one way and used both as an instructor I can no longer understand why folk want to persist with believeing that attitude controls speed and power controls RoD.
Sure, (presuming you do nothing with the power) if you lower the nose you'll gain speed, or if you raise it, you'll lose speed BUT you'll also alter the flight path.
As stated in an earlier post, IF one subscribes to the belief that the primary effect of power is to control speed, and the primary effect of pitch is to control the flight path then this premise applies to all flight regimes. One must remain cognisant of the secondary effect of pitch and power, but one doesn't have to change one's thinking just because one is in the circuit for a landing.
For example, if cruising along the beech at 500' enjoying the view one became aware that last light was encroaching and one needed to speed up to arrive before last light, would you [list=1][*]Lower the nose to speed up, or[*]open the throttle?[/list=1]
Coffin corner doesn't apply to C150 et al. It's where, due to compressability, the Vmo and Vs meet.
Most lighties can't get high enough or fast enough when high to have the problem.
You said,
In landing a light aircraft, control your speed by pitch attitude and use the throttle to maintain your flight path as you are taught. It's easier that way because the speed will respond quicker to pitch changes than to engine speed changes.
, more importantly, it was contrary to what I was taught and what I knew!!!!!!)So having learned one way and used both as an instructor I can no longer understand why folk want to persist with believeing that attitude controls speed and power controls RoD.
Sure, (presuming you do nothing with the power) if you lower the nose you'll gain speed, or if you raise it, you'll lose speed BUT you'll also alter the flight path.
As stated in an earlier post, IF one subscribes to the belief that the primary effect of power is to control speed, and the primary effect of pitch is to control the flight path then this premise applies to all flight regimes. One must remain cognisant of the secondary effect of pitch and power, but one doesn't have to change one's thinking just because one is in the circuit for a landing.
For example, if cruising along the beech at 500' enjoying the view one became aware that last light was encroaching and one needed to speed up to arrive before last light, would you [list=1][*]Lower the nose to speed up, or[*]open the throttle?[/list=1]
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Hear hear bushy but if ya flying one them pointy jetty things it works all arse backwards.
If ya want to get down the ILS ya point the bugger down and use watever else you got to slow it down, most aces can leave the power at idle from TOD to late final
If it gets a lil slow apply the kero
Bloody simple really but takes a while for old prop jockeys ta get the hang of it.
If ya want to get down the ILS ya point the bugger down and use watever else you got to slow it down, most aces can leave the power at idle from TOD to late final
If it gets a lil slow apply the kero
Bloody simple really but takes a while for old prop jockeys ta get the hang of it.
Yes clarrie, the "or" at the end of 'option' 1 is misleading.
My point (which I am comforted to note the author of Aerodynamics for Naval Aviators appears to support) is that if you just "open the throttle", you'll merely begin to climb without increasing airspeed, you won't get there any quicker (assuming you don't pick up a tailwind as you climb) and you will run out of juice sooner than you otherwise would have.
If you want to go faster, lower the nose. If you want to go faster and not descend, lower the nose and increase power.
My point (which I am comforted to note the author of Aerodynamics for Naval Aviators appears to support) is that if you just "open the throttle", you'll merely begin to climb without increasing airspeed, you won't get there any quicker (assuming you don't pick up a tailwind as you climb) and you will run out of juice sooner than you otherwise would have.
If you want to go faster, lower the nose. If you want to go faster and not descend, lower the nose and increase power.