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  #1  
Old 11-12-2022, 07:07 PM
Vac Vac is offline
 
Join Date: Jul 2009
Location: Niceville, Florida
Posts: 535
Default Energy Management in Three Minutes

Energy is power from the engine converted into some combination of airspeed and altitude. We control energy with the throttle and “distribute” it with angle of attack (elevator). In simple terms there are three energy states: positive (more thrust than drag and the airplane can go up, speed up or both); neutral (thrust and drag are balanced); and negative (more drag than thrust and the airplane will slow down, go down or both). Neutral energy is associated with minimum power required, which also correlates with onspeed angle of attack. If you know what your angle of attack is relative to an onspeed condition, you know your energy state for a given throttle position, gross weight, and G load. Pretty simple if you know whether you are “fast” or “slow” relative to onspeed AOA. Any “slow” tone and you know you are behind the power curve and must reduce AOA, add power or both: https://youtu.be/hxnwsfCneyc

Chapter 4 in the Airplane Flying Handbook has a great energy management discussion. An electronic version can be downloaded from the FAA here: https://www.faa.gov/sites/faa.gov/fi...0_afh_full.pdf. Worth a read if you haven't already.

May the P sub S be with you,

Vac
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  #2  
Old 11-13-2022, 06:45 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
Join Date: May 2005
Location: Savannah, GA
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Here's what it looks like to fly without reference to airspeed or altitude, only energy, as per Chapter 4 of the Airplane Flying Handbook. And there are no instruments in the plane that directly measure kinetic and potential energy -- those have to be derived from airspeed and altitude.

https://www.youtube.com/watch?v=y7vGaI47SsI
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RV-9A at KSAV (Savannah, GA; dual G3X Touch with autopilot, GTN650, GTX330ES, GDL52 ADSB-In)
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  #3  
Old 11-13-2022, 08:43 AM
Vac Vac is offline
 
Join Date: Jul 2009
Location: Niceville, Florida
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Hi Ed,

Happy Sunday. Sarcasm noted.

Your video is an excellent play by play narration of what’s happening real time. All I’m suggesting is that we make the physics simple, intuitive, and accessible. Not understanding energy state leads to turn, stall, die syndrome.

I use a different technique to fly a closed pattern than you do. I can’t even say what my kinetic energy is in this case since I don’t have any airspeed indication in the cockpit in this example. But I do know precisely what my AOA and specific power are, which makes maneuvering safe and straightforward: https://youtu.be/c7u6AzOQweQ

AOA is the only operational parameter a wing “sees” and controls airspeed: https://www.nar-associates.com/techn...ide_screen.pdf. Knowing my AOA helps a knuckle dragger like me understand my energy state and stall margin. I understand that you aren’t a fan, and your mind appears to be made up regarding its tactical utility. We share a common objective to help reduce handling error that leads to a loss of control or undesired aircraft state and improve resources for pilots. That was also the intent behind adding Chapter 4 to the Airplane Flying Manual. I had the pleasure of serving with the author at Test Ops at Eglin. We still keep in touch as we try to move the safety dial.

Respectfully,

Vac
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Last edited by Vac : 11-13-2022 at 08:47 AM.
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  #4  
Old 11-13-2022, 10:01 AM
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erich weaver erich weaver is offline
 
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Location: santa barbara, CA
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The onspeed system with audio cues seems intuitive to me and I look forward to the day there is a plug and play version that ties in with my GRT EFIS.

Very nice response to Ed’s post as well
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Last edited by erich weaver : 11-13-2022 at 08:39 PM.
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  #5  
Old 11-13-2022, 11:51 AM
Strikhedonia Strikhedonia is offline
 
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Location: Steamboat Springs, CO
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Great videos and demonstration. Thank you for putting these together.
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  #6  
Old 11-26-2022, 10:49 AM
Vac Vac is offline
 
Join Date: Jul 2009
Location: Niceville, Florida
Posts: 535
Default 3-minute read: What is “specific power,” and how does it help us determine energy st

About 60 years ago, John Boyd and his team at Eglin AFB Test developed a method to directly compare the performance of two fighter aircraft. The purpose was to determine areas of the performance envelope where one airplane has a maneuvering advantage or deficit relative to a different type. This work caused a fundamental shift in the fighter community and the way we taught folks to dogfight. It also led to integration of better energy management tools in the cockpit as well as revisions to the training syllabus—i.e., how we taught folks to fly. This shift improved combat efficacy and resulted in reduction in loss of control mishaps.

Before you stop reading because “military flying isn’t general aviation” please consider that airplanes are airplanes and physics is physics

Let’s take a brief look at what “specific power” (abbreviated Ps and pronounced “p sub s”) is and why the pilot cares…

…Ultimately, it’s just an easy way to analyze the four forces that you learned about for your private pilot written test. Technically it’s thrust x velocity minus drag x velocity divided by gross weight x G-load. As stick-actuators, all we need to know is the relationship between thrust and drag for our current G-load as we maneuver the airplane. Using Ps is an easy way to do that if you have a properly calibrated AOA system in the airplane. It eliminates math in public and tells us what to do with the stick and throttle to avoid a negative energy state or optimize performance.

In my initial post, I’m substituting Ps for “energy state." AOA (whether you look at it or listen to it) is the key to knowing where you are on the power required curve since there are specific AOAs associated with minimum power and maximum lift to drag ratio. AOA also tells you exactly how far from a stall you are. Us knuckle-dragging stick apes refer to this situational awareness as “knowing our aerodynamic margin” which makes us sound smart at the bar (and engineers cringe), but just means “how hard can I pull right now?”

Key performance AOAs are built into the airplane and don’t change except during flap deployment. That means your approach and landing reference AOA remains the same regardless of gross weight, density altitude or G-load. The three-tone pattern is just a simple way to convey “onspeed, fast or slow” to the pilot during maneuvering. It allows instantaneous determination of Ps, correlates with Vapp/Vref (1.3 Vs), and Vx. If the objective is to maintain onspeed for approach and landing, the tone is a simple “push/pull” cue. The same is true during maneuvering flight. Unless the intention is to add drag using G, or maneuver at the aerodynamic limit of the airplane, there isn’t any reason for the pilot to spend any time in the slow tone.

We use the throttle to “make energy” and the elevator to manage it. If we know AOA, we know specific power and how we can use the elevator to trade that throttle position for altitude, airspeed, optimum approach or optimum turn performance, real-time. That performance SA and progressive stall warning are what AOA bring to the fight. It's a simple, efficient way to manage energy and maintain control of an airplane with manual flight controls.

Fly safe,

Vac
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RV-4 2112
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Last edited by Vac : 11-26-2022 at 10:51 AM.
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