Talk:Steady flight

Do we really need all the trig?

I got my private license and my dispatch license without ever having to learn trigonometry. This article is about steady flight, which is a relatively simple aeronautical concept. Forces in balance. This article looks uninviting and intimidating. It takes a relatively simple subject and makes it seem very confusing. That is the opposite of teaching. Who are the readers? What are they looking for? How does an article like this serve a typical student pilot? Not every article needs to look like a college physics text, and I think we do that too often in WP. Leave the flight dynamics equations to the flight dynamics article. Dcs002 (talk) 08:45, 6 January 2016 (UTC)

Hello, thanks for the comments. I wrote this article after teaching steady flight to college sophomores and flight dynamics to college juniors at a university aerospace engineering program. I noticed that the flight dynamics page presented the differential equations describing flight dynamics, but there was no scaled-back version with the static equations showing the force balance when airplanes fly in equilibrium. I also noticed that Wikipedia lacked a careful description of the reference frames and angles used for flight dynamics. I added the detailed description of the reference frames to the flight dynamics page and summarized them here to be able to point out the axes and angles used in the steady flight equations. I left the trigonometry in for three reasons:

1. You can't show the mathematical relationship between bank angle, turning, and lift without sin & cos
2. Steady flight assumes small angle of attack, flight path angle, and sideslip angle; some readers will find it useful to see what those assumptions mean mathematically
3. The axes where it's easy to express the force balance are not obvious, so the trig gives a reader trying to recreate the equations in a computer model or a homework assignment a clue as to what rotations were required to express the forces along the specified axes

Steady flight is defined as flight with no net acceleration. This means the forces of lift, thrust, drag, and weight all cancel out and the plane is left to fly at a constant velocity whether this is level flight, a climb or a shallow dive.

I'm also a private pilot and I wholeheartedly agree that knowledge of these equations was only marginally useful during flight training. I'd welcome someone adding a section and citation above the reference frames section that describes what steady flight is without any math. In flight training, you can get by with the diagram and caption that Narkulome added to the lead in 2017 about forces canceling (copied here before my edits to it). However, as soon as you try to write down the equations you realize that the diagram is not accurate:

• It shows lift, weight, and drag on the wrong axes
• Lift and drag are really just components of another force, the aerodynamic force
• The aerodynamic force has a a third component that's not pictured, the side force
• Turns–which require acceleration–can be steady flight maneuvers, so the caption is only true if the airplane isn't turning

Besides a math-free explanation, here are some other steady flight topics that could be added that would be of more interest to pilots:

• Adding the steady flight equation for the pitching moment, which shows how to choose the elevator control input or elevator trim setting
• Showing that drag and lift are functions of velocity, which leads to the link between throttle setting, airspeed, and bank angle
• Constraints on steady flight (stall constraint, thrust constraint, load factor constraint) and the steady flight envelope
• Diagrams showing the reference frames and the angles linking them

I stopped where I did partly because of a time constraint but mainly because those are covered well in McClamroch's textbook and I didn't want to rewrite his entire book on Wikipedia. Error9312 (talk) 03:47, 18 May 2020 (UTC)