Pitch & Power, Altitude & Airspeed Question

[VNugget]

Controlling airspeed in a power off glide is light years beyond what a student needs to know?

 

[FlyBieWire]

I just got home from school and have now read all the replies to my question. Thank you all for your help.

I can see the answer to my question is not cut and dry. I do like UndauntedFlyer's Flight Path Mode (FPM) and Altitude Change Mode (ACM) explanation. I don't think I have read it anywhere else but it seems to make the most sense to me at this point in my training.

I’m sure there are going to be exceptions to any rule but I like the concept of the role reversal of power and pitch as the Modes change.

 

[UndauntedFlyer]

Controlling airspeed in a power off glide is light years beyond what a student needs to know?

Controlling airspeed and angle/rate of descent when beyond the limits of the demand is light years beyond the objectives of this thread.

As for the above question only, then you are in a Altitude Change Mode until the assigned altitude is captured.

 

[UndauntedFlyer]

I’m sure there are going to be exceptions to any rule but I like the concept of the role reversal of power and pitch as the Modes change.

The role reversal concept is the most important difference in this explanation vs. Wolfgang's "Stick & Rudder" explanation. No automatic airplane could possibly fly until the two modes, FLIGHT PATH MODE & ALTIDUDE CHANGE MODE were separated. And I will say that no pilot can fly an airplane until he/she understands this either, consciously or unconsciously.

Your questions or comments are welcome.....

 

[pilotyip]

I only know what I learned landing solo on an aircraft carrier in the T-28C with a total of 125 hours of flt time. If the meatball goes one index high reduce power 1", if the meatball goes low one index add 1" of power. Power effects your descent rate. If airspeed in above 82 Kts, raise the nose, if airspeed is below 82 Kts lower the nose. Nose attitude effects your airspeed. Seemed to work for me.

 

[Alamanach]

rate of climb = (power available - power required) / weight

Can you explain what "power available" and "power required" are?


I agree with FlyBieWire, I like the FPM/ ACM explanation too. And I think the existence FMS is a strong point in favor of Undaunted Flyer's main argument. But...

FLIGHT PATH MODE applies when the airplane is operating on a fixed FLIGHT PATH, such as in cruise or descending on a glide path like an ILS glide slope, VASI or even a VNAV path... ALTITUDE CHANGE MODE applies when the airplane must make LARGE CHANGES IN ALTITUDE either in a climb or in a descent without concern to a particular path.

from an engineering standpoint, what makes the "fixed" flight path of FPM different from the unspecified flight path of ACM? There are similar forces and similar dynamics at play, and it is not obvious what distinguishes one flight mode from the other (in a mathematical/ physical/ engineering sense). Unless the distinction is simply that FPM is a more precise mode of flying. If that is the case... we may be back to square one.

 

[UndauntedFlyer]

Can you explain what "power available" and "power required" are?


I agree with FlyBieWire, I like the FPM/ ACM explanation too. And I think the existence FMS is a strong point in favor of Undaunted Flyer's main argument. But...



from an engineering standpoint, what makes the "fixed" flight path of FPM different from the unspecified flight path of ACM? There are similar forces and similar dynamics at play, and it is not obvious what distinguishes one flight mode from the other (in a mathematical/ physical/ engineering sense). Unless the distinction is simply that FPM is a more precise mode of flying. If that is the case... we may be back to square one.

I would not really want to explain the Power available vs. Power required idea. That is something altogether different from the concept in this thread.

Now regarding the FPM differences from the ACM. Besides what has already been mentioned the answer is that ACM mode always has the throttle in a fixed position such as idle or maybe 1800 RPM for descents. And then the throttle will be at takeoff or climb power for climbs. In the FPM the throttle would normally be somewhere in the middle moving as necesasry for airspeed control.

 

[Alamanach]

...the answer is that ACM mode always has the throttle in a fixed position such as idle or maybe 1800 RPM for descents. And then the throttle will be at takeoff or climb power for climbs. In the FPM the throttle would normally be somewhere in the middle moving as necesasry for airspeed control.

Someone must have paid my electric bill... the lights just went on! Thanks, I'll go think this over.

 

[3BCat]

FlyBieWire

Pitch , Power and Trim. I'm glad you found an explanation that you like. Just remember, its best not to run out of airspeed, altitude and ideas all at the same time!

Keep 'em flyin'!

 

[VNugget]

Can you explain what "power available" and "power required" are?

Power required is the power required to maintain level flight at any given speed. Power available is the actual power produced by the engine/prop at the moment. If the Pavailable = Prequired you're gonna be in level flight. If Pavailable exceeds Prequired, then you have excess power and you're gonna climb. If Pavailable is less than Prequired, then there's a deficiency of power and you're gonna descend.

If you have an engineer's aproach to things, I highly recommend this book: Aerodynamics for Naval Aviators. It may not be easy to digest; I'm not an engineer (I failed out of first year college calculus twice) but each section makes sense after a couple of read-throughs. The more I understood from it, the more I connected the basic underlying flight mechanics principles to how an airplane behaves in real life, thus increasing the connection between man and machine.