I am glad to see Kitplanes banging the drum on this. I have long advocated this and am including it in my S-21 build. I appreciate the work Dan Gryder is doing and have tried a few times to get him to get on the bandwagon to no avail. His airspeed indicator placards are just a bandaid. Yes, they are a bigger bandaid than a bare airspeed indicator, but a bandaid nonetheless. AoA is the real solution as it directly measures what matters and isn’t a constantly changing surrogate.
@@LTVoyager As Vy depends on maximum excess power and Vx depends upon maximum excess thrust, and as these curves are not linear, you do not have an AOA value to which to tie to them. It is also a bad habit for when you go to multi-engine planes with concerns for minimum controllability speeds; rudders don’t care about the wings’ AOA. See my other comments to this video.
@@LTVoyager also, what is your AOA just turning onto the runway at three knots? At ten knots as you start your takeoff roll? Forty knots still on the ground roll? Just before rotate? So, seeing how they’re all the same, likely at zero except should your wings have a built in angle relative to longitudinal axis, how would you even use AOA for a takeoff?
@@jimallen8186 Why use absolutely meaningless arguments against a very useful tool like AoA? Trim is useless on the runway also. Does that mean we shouldn’t have trim tabs on airplanes?
This is a great segue to a series on installing, calibrating, understanding and flying AoA. For example, discussing how critical AoA changes with flap extension, etc. Hint, hint…
It is more than AOA, also apply Power Techniques with AOA. Search Medium for “Improve your Landings with AOA and Power Techniques” and the correlating “F-35C Crash into the South China Sea - A Case Study.” Important, try slow flight with constant AOA turns instead of constant airspeed turns. Note you do not have to pull back to turn, add power to maintain desired descent to include staying level. Use power to control the descent, trim to maintain AOA and you won’t need back stick till round out and flare.
The change is relatively small on most GA airplanes and isn’t a significant factor during a normal approach and landing. Larger, faster jets with large Fowler flaps and leading edge slats generally have inputs for flap and slat setting into the AoA instrument so that compensation can be made.
Electronic ones with integrated flap position calibrate each wing configuration. For my pneumatic analog Lift Reserve, however, I have bench marks on the gauge for each flap setting. I also rotated the face 90 clockwise so high is up instead of left.
I’ve a thought experiment for you: consider Vx and Vy meet at your airplane’s ceiling. This means Vy in terms of IAS gets slower while Vx in terms of IAS gets faster till they meet. (In terms of TAS, both get faster but Vx gets faster quicker hence they meet.) So, if you have two values that generally are different in terms of Vx and Vy, how can they each have a distinct correlating AOA seeing how they meet as you climb to your service ceiling? AOA is great, but perhaps not for takeoffs and climbs. You can’t give me an AOA for Vx and another for Vy as we just proved Vx = Vy at some point in your performance profile while they differ at all other points. AOAs cannot be both distinct and also vary so as to permit such to occur by being equal at some point. AOAs are not for going up. They’re for staying level and heading down. Be careful suggesting AOA for takeoffs. You’re under energy if you use “green donut,” or on-speed AOAref to climb. Most airframes have a best glide that is faster than 1.3 Vso and Vref is 1.3 Vso in straight flight meaning AOAref is also 1.3 Vso if neither in an AOB nor applying a pitch rate (aka actively changing pitch) meaning AOAref “green donut” is a higher AOA slower flight than best glide. Better to be at a lower AOA than “best AOA” so as to have margin for startle time if you’re going to use it. Remember also, Climbs are not strictly based on “best lift,” as really they are based on drag versus power and drag versus thrust with power excess for best rate while thrust excess gives best angle. Are your power available and thrust available curves linear? Or linear in the region near L/Dmax? Note what Aerodynamics for Naval Aviators stated regarding L/Dmax: Many important items of airplane performance are obtained in flight at (L/D)max. Typical performance conditions which occur at (L/D)max, are: - maximum endurance of jet powered airplanes - maximum range of propeller driven airplanes [in still air] - maximum climb angle for jet powered airplanes - maximum power-off glide range, jet or prop [in still air] The most immediately interesting of these items is the power-off glide range of an airplane. By examining the forces acting on an airplane during a glide, it can be shown that the glide ratio is numerically equal to the lift-drag ratio. For example, if the airplane in a glide has an L/D of 15, each mile of altitude is traded for 15 miles of horizontal distance. Such a fact implies that the airplane should be flown at L/Dmax to obtain the greatest glide distance. An unbelievable feature of gliding performance is the effect of airplane gross weight. Since the maximum lift-drag ratio of a given airplane is an intrinsic property of the aerodynamic configuration, gross weight will not affect the gliding performance. If a typical jet trainer has an L/Dmax of 15, the aircraft 1 can obtain a maximum of 15 miles horizontal distance for each mile of altitude. This would be true of this particular airplane at any gross weight if the airplane is flown at the angle of attack for L/Dmax. Of course, the gross weight would affect the glide airspeed necessary for this particular angle of attack but the glide ratio would be unaffected. (You can search James Albright with Code 7700 and see the Air Force recognizes and teaches the same stuff here.) What is missing from both Navy and Air Force training? AOA for takeoffs and climbs. L/Dmax is a constant AOA value but it is NOT reference AOA or “on-speed.” Best Glide is not “green donut.” If you take off on green donut, you’re too slow. Your AOA is too high. In addition to this, you may want shallower climbs for visibility over the nose, for getting away from traffic by having faster speed, for engine cooling airflow. Having a limit to go no higher than for AOA in takeoff is a good idea, but you should still use airspeed for takeoff. You should have a rotate speed and a liftoff speed. Think about twins too, you need controllable speed and that has nothing to do with AOA. Vmca has no clue what is your AOA. Neither does Vmcg. Taking off on AOA is dangerous. Do you have a “continuation speed” on your takeoff roll? You should already be looking at speeds to know if you should continue or abort, when to rotate, and oh by the way, AOA gets skewed on the runway and in ground effect while your center of pressure is also shifted in ground effect (see Australian sea skimmer research). Teaching AOA flying is great but DO NOT TEACH ON-SPEED AOA FOR TAKEOFFS. BETTER TO STAY AWAY FROM AOA ON TAKEOFF RESERVING IT FOR SLOW FLIGHT AND LANDINGS. Note AOA is good for maximum endurance, best glide time, max range if no wind, best glide if no wind, and is ideal for AOAref in the pattern and landing though you may still want to fly faster in the pattern for carrying some contingency energy.
Those more familiar with Aerodynamics for Naval Aviators may counter with “During takeoff where the airplane must not be over-rotated to an excessive angle of attack. Any given airplane will have some fixed angle of attack (and Cl) which produces the best takeoff performance and this angle of attack will not vary with weight, density altitude, or temperature.” Yes, the book stated this, but this is strictly aerodynamics of the wing in a context. It fails to account for Vmca. It fails to define with a definition as to what is “best,” is it best angle or best rate or something else entirely. [I’d presume the author meant best angle for jets as this is knowable as L/Dmax with a linear thrust available curve.] It also fails to account for your AOA not changing during your ground roll assuming tricycle gear or after lifting the tail for conventional gear. As your wing chord does not change angle relative to the wheels while you roll and your relative wind is opposite your roll, functionally, how could you use AOA? Your AOA does not change as you accelerate down a runway. The book does, however, provide context after the statement and this context leans more towards using AOA as a limit on takeoff and initial climb not as a sought target value. “An excessive angle of attack produces additional induced drag and may have an undesirable effect on takeoff performance. Takeoff acceleration may be seriously reduced and a large increase in takeoff distance may occur. Also, the initial climb performance may be marginal at an excessively low airspeed. There are modern configurations of airplanes of very low aspect ratio (plus sweepback) which-if over-rotated during a high altitude, high gross weight takeoff-cannot fly out of ground effect. With the more conventional airplane configuration, an excess angle of attack produces a well defined stall. However, the modern airplane configuration at an excessive angle of attack has no sharply defined stall but developes an excessive amount of induced drag. To be sure that it will not go unsaid, an excessively low angle of attack on takeoff creates its own problems-excess takeoff speed and distance and critical tire loads.” You can RUclips Canard Boulevard to see an instance in which he experiences a nose wheel bounce causing early liftoff with excessively high AOA in the IGE to OGE transition preventing him from actually climbing. Limiting AOA in takeoff is good. This is not the same as using an AOA value for takeoff, however. The lighter you are, the less airspeed you’ll have for a given AOA, the more likely you are to be less than Vmca. Note the F/A-18 provides AOA limits for half and full flaps for the sake of ensuring controllability. Unlike most performance measures, these needed to account for empty weight aft cg not max weight forward cg. Weakest rudders with smallest moment arm and least airflow.
More from Naval Aviators: “The thrust curves for the representative propeller aircraft show the typical propeller thrust which is high at low velocities and decreases with an increase in velocity. For the propeller powered airplane, the maximum excess thrust and angle of climb will occur at some speed just above the stall speed. Thus, if it is necessary to clear an obstacle after takeoff, the propeller powered airplane will attain maximum angle of climb at an airspeed conveniently close to-if not at-the takeoff speed.” Do you really want to be at this AOA in initial climb? Didn’t think so. “The power curves for the representative propeller aircraft show a variation of propulsive power typical of a reciprocating engine-propeller combination. The maximum rate of climb for this aircraft will occur at some speed near the speed for L/Dmax. There is no direct relationship which establishes this situation since the variation of propeller efficiency is the principal factor accounting for the variation of power available with velocity. In an ideal sense, if the propeller efficiency were constant, maximum rate of climb would occur at the speed for minimum power required. However, in the actual case, the propeller efficiency of the ordinary airplane will produce lower power available at low velocity and cause the maximum rate of climb to occur at a speed greater than that for minimum power required.” You’ve too much reliance on power production to use bare airframe response hence can’t rely on a hard AOA. Your power available curve is not linear. Nor is thrust.
Speed Keep your speed at 1.5 stall speed in the landing pattern until in final approach. A fatal crash today. a small plane turning in the landing pattern ...ordered by the ATC to make a turn...stalls and spins into the ground
How do you know V stall iot maintain 1.5 of such? Remember at 60 AOB, stall is double straight stall. If, however, you use AOA, you can always see your margin. If you don’t pull back on the stick, your nose may cut down and descent rate increase, but you won’t stall.
So why the hell were we taught to fly only with airspeed in the '80s? I wonder who thought that a good idea, when all military pilots were always taught with AofA....
Because until the last decade or so, AoA instruments were relatively expensive and required frequent calibration. Today’s electronics allow relatively inexpensive AoA instruments. It is the same reason we didn’t have jet engines in 1910.
Can you spell FAA! Everything is slow and expensive ( & because it’s expensive it is slower yet, forward feedback loop) in GA because of control freak bureaucrats!!!
I'm glad someone is finally really pushing AoA. STOL pilots have been using it and trying to get the message out about how great it is for some time now.
I am glad to see Kitplanes banging the drum on this. I have long advocated this and am including it in my S-21 build. I appreciate the work Dan Gryder is doing and have tried a few times to get him to get on the bandwagon to no avail. His airspeed indicator placards are just a bandaid. Yes, they are a bigger bandaid than a bare airspeed indicator, but a bandaid nonetheless. AoA is the real solution as it directly measures what matters and isn’t a constantly changing surrogate.
Except in takeoff. It is a mistake to use it for takeoff and climb.
@@jimallen8186 Why?
@@LTVoyager As Vy depends on maximum excess power and Vx depends upon maximum excess thrust, and as these curves are not linear, you do not have an AOA value to which to tie to them. It is also a bad habit for when you go to multi-engine planes with concerns for minimum controllability speeds; rudders don’t care about the wings’ AOA. See my other comments to this video.
@@LTVoyager also, what is your AOA just turning onto the runway at three knots? At ten knots as you start your takeoff roll? Forty knots still on the ground roll? Just before rotate? So, seeing how they’re all the same, likely at zero except should your wings have a built in angle relative to longitudinal axis, how would you even use AOA for a takeoff?
@@jimallen8186 Why use absolutely meaningless arguments against a very useful tool like AoA? Trim is useless on the runway also. Does that mean we shouldn’t have trim tabs on airplanes?
This is a great segue to a series on installing, calibrating, understanding and flying AoA. For example, discussing how critical AoA changes with flap extension, etc. Hint, hint…
It is more than AOA, also apply Power Techniques with AOA. Search Medium for “Improve your Landings with AOA and Power Techniques” and the correlating “F-35C Crash into the South China Sea - A Case Study.” Important, try slow flight with constant AOA turns instead of constant airspeed turns. Note you do not have to pull back to turn, add power to maintain desired descent to include staying level. Use power to control the descent, trim to maintain AOA and you won’t need back stick till round out and flare.
May also want to try Medium “Back Side of the Power Curve vs Drag Curve”
Surely critical aoa changes with flap settings. How do the various systems deal with this?
The change is relatively small on most GA airplanes and isn’t a significant factor during a normal approach and landing. Larger, faster jets with large Fowler flaps and leading edge slats generally have inputs for flap and slat setting into the AoA instrument so that compensation can be made.
Electronic ones with integrated flap position calibrate each wing configuration. For my pneumatic analog Lift Reserve, however, I have bench marks on the gauge for each flap setting. I also rotated the face 90 clockwise so high is up instead of left.
@@LTVoyagerThanks for the answer. Greatly appreciated
I’ve a thought experiment for you: consider Vx and Vy meet at your airplane’s ceiling. This means Vy in terms of IAS gets slower while Vx in terms of IAS gets faster till they meet. (In terms of TAS, both get faster but Vx gets faster quicker hence they meet.) So, if you have two values that generally are different in terms of Vx and Vy, how can they each have a distinct correlating AOA seeing how they meet as you climb to your service ceiling? AOA is great, but perhaps not for takeoffs and climbs. You can’t give me an AOA for Vx and another for Vy as we just proved Vx = Vy at some point in your performance profile while they differ at all other points. AOAs cannot be both distinct and also vary so as to permit such to occur by being equal at some point. AOAs are not for going up. They’re for staying level and heading down.
Be careful suggesting AOA for takeoffs. You’re under energy if you use “green donut,” or on-speed AOAref to climb. Most airframes have a best glide that is faster than 1.3 Vso and Vref is 1.3 Vso in straight flight meaning AOAref is also 1.3 Vso if neither in an AOB nor applying a pitch rate (aka actively changing pitch) meaning AOAref “green donut” is a higher AOA slower flight than best glide.
Better to be at a lower AOA than “best AOA” so as to have margin for startle time if you’re going to use it. Remember also, Climbs are not strictly based on “best lift,” as really they are based on drag versus power and drag versus thrust with power excess for best rate while thrust excess gives best angle. Are your power available and thrust available curves linear? Or linear in the region near L/Dmax?
Note what Aerodynamics for Naval Aviators stated regarding L/Dmax:
Many important items of airplane performance are obtained in flight at (L/D)max. Typical performance conditions which occur at (L/D)max, are:
- maximum endurance of jet powered airplanes
- maximum range of propeller driven airplanes [in still air]
- maximum climb angle for jet powered airplanes
- maximum power-off glide range, jet or prop [in still air]
The most immediately interesting of these items is the power-off glide range of an airplane. By examining the forces acting on an airplane during a glide, it can be shown that the glide ratio is numerically equal to the lift-drag ratio. For example, if the airplane in a glide has an L/D of 15, each mile of altitude is traded for 15 miles of horizontal distance. Such a fact implies that the airplane should be flown at L/Dmax to obtain the greatest glide distance.
An unbelievable feature of gliding performance is the effect of airplane gross weight. Since the maximum lift-drag ratio of a given airplane is an intrinsic property of the aerodynamic configuration, gross weight will not affect the gliding performance. If a typical jet trainer has an L/Dmax of 15, the aircraft 1 can obtain a maximum of 15 miles horizontal distance for each mile of altitude. This would be true of this particular airplane at any gross weight if the airplane is flown at the angle of attack for L/Dmax. Of course, the gross weight would affect the glide airspeed necessary for this particular angle of attack but the glide ratio would be unaffected.
(You can search James Albright with Code 7700 and see the Air Force recognizes and teaches the same stuff here.) What is missing from both Navy and Air Force training? AOA for takeoffs and climbs.
L/Dmax is a constant AOA value but it is NOT reference AOA or “on-speed.” Best Glide is not “green donut.” If you take off on green donut, you’re too slow. Your AOA is too high.
In addition to this, you may want shallower climbs for visibility over the nose, for getting away from traffic by having faster speed, for engine cooling airflow. Having a limit to go no higher than for AOA in takeoff is a good idea, but you should still use airspeed for takeoff. You should have a rotate speed and a liftoff speed. Think about twins too, you need controllable speed and that has nothing to do with AOA. Vmca has no clue what is your AOA. Neither does Vmcg. Taking off on AOA is dangerous.
Do you have a “continuation speed” on your takeoff roll? You should already be looking at speeds to know if you should continue or abort, when to rotate, and oh by the way, AOA gets skewed on the runway and in ground effect while your center of pressure is also shifted in ground effect (see Australian sea skimmer research).
Teaching AOA flying is great but DO NOT TEACH ON-SPEED AOA FOR TAKEOFFS. BETTER TO STAY AWAY FROM AOA ON TAKEOFF RESERVING IT FOR SLOW FLIGHT AND LANDINGS. Note AOA is good for maximum endurance, best glide time, max range if no wind, best glide if no wind, and is ideal for AOAref in the pattern and landing though you may still want to fly faster in the pattern for carrying some contingency energy.
Those more familiar with Aerodynamics for Naval Aviators may counter with “During takeoff where the airplane must
not be over-rotated to an excessive angle of
attack. Any given airplane will have some
fixed angle of attack (and Cl) which produces
the best takeoff performance and this angle
of attack will not vary with weight, density
altitude, or temperature.” Yes, the book stated this, but this is strictly aerodynamics of the wing in a context. It fails to account for Vmca. It fails to define with a definition as to what is “best,” is it best angle or best rate or something else entirely. [I’d presume the author meant best angle for jets as this is knowable as L/Dmax with a linear thrust available curve.] It also fails to account for your AOA not changing during your ground roll assuming tricycle gear or after lifting the tail for conventional gear. As your wing chord does not change angle relative to the wheels while you roll and your relative wind is opposite your roll, functionally, how could you use AOA? Your AOA does not change as you accelerate down a runway. The book does, however, provide context after the statement and this context leans more towards using AOA as a limit on takeoff and initial climb not as a sought target value. “An excessive angle
of attack produces additional induced drag
and may have an undesirable effect on takeoff
performance. Takeoff acceleration may be
seriously reduced and a large increase in takeoff distance may occur. Also, the initial
climb performance may be marginal at an
excessively low airspeed. There are modern
configurations of airplanes of very low aspect
ratio (plus sweepback) which-if over-rotated during a high altitude, high gross
weight takeoff-cannot fly out of ground
effect. With the more conventional airplane
configuration, an excess angle of attack produces a well defined stall. However, the
modern airplane configuration at an excessive
angle of attack has no sharply defined stall
but developes an excessive amount of induced
drag. To be sure that it will not go unsaid,
an excessively low angle of attack on takeoff
creates its own problems-excess takeoff speed and distance and critical tire loads.” You can RUclips Canard Boulevard to see an instance in which he experiences a nose wheel bounce causing early liftoff with excessively high AOA in the IGE to OGE transition preventing him from actually climbing. Limiting AOA in takeoff is good. This is not the same as using an AOA value for takeoff, however. The lighter you are, the less airspeed you’ll have for a given AOA, the more likely you are to be less than Vmca. Note the F/A-18 provides AOA limits for half and full flaps for the sake of ensuring controllability. Unlike most performance measures, these needed to account for empty weight aft cg not max weight forward cg. Weakest rudders with smallest moment arm and least airflow.
More from Naval Aviators: “The thrust curves for the representative propeller aircraft show the typical propeller thrust
which is high at low velocities and decreases
with an increase in velocity. For the propeller powered airplane, the maximum excess
thrust and angle of climb will occur at some
speed just above the stall speed. Thus, if it
is necessary to clear an obstacle after takeoff,
the propeller powered airplane will attain
maximum angle of climb at an airspeed conveniently close to-if not at-the takeoff
speed.”
Do you really want to be at this AOA in initial climb? Didn’t think so.
“The power curves for the representative propeller aircraft show a variation of propulsive
power typical of a reciprocating engine-propeller combination. The maximum rate of
climb for this aircraft will occur at some speed near the speed for L/Dmax. There is no direct
relationship which establishes this situation
since the variation of propeller efficiency is the
principal factor accounting for the variation
of power available with velocity. In an ideal
sense, if the propeller efficiency were constant,
maximum rate of climb would occur at the
speed for minimum power required. However, in the actual case, the propeller efficiency
of the ordinary airplane will produce lower
power available at low velocity and cause the
maximum rate of climb to occur at a speed
greater than that for minimum power required.”
You’ve too much reliance on power production to use bare airframe response hence can’t rely on a hard AOA. Your power available curve is not linear. Nor is thrust.
Speed
Keep your speed at 1.5 stall speed in the landing pattern until in final approach.
A fatal crash today. a small plane turning in the landing pattern ...ordered by the ATC to make a turn...stalls and spins into the ground
How do you know V stall iot maintain 1.5 of such? Remember at 60 AOB, stall is double straight stall. If, however, you use AOA, you can always see your margin. If you don’t pull back on the stick, your nose may cut down and descent rate increase, but you won’t stall.
So why the hell were we taught to fly only with airspeed in the '80s? I wonder who thought that a good idea, when all military pilots were always taught with AofA....
Because until the last decade or so, AoA instruments were relatively expensive and required frequent calibration. Today’s electronics allow relatively inexpensive AoA instruments. It is the same reason we didn’t have jet engines in 1910.
Can you spell FAA! Everything is slow and expensive ( & because it’s expensive it is slower yet, forward feedback loop) in GA because of control freak bureaucrats!!!
See Medium Improve Your Landings with AOA and Power Techniques and note the anecdote about monkeys.
I'm glad someone is finally really pushing AoA. STOL pilots have been using it and trying to get the message out about how great it is for some time now.
Do they take off and climb with it? Or is it for landing? See my comments above.