I prefer to call it the region of Reverse Demand as opposed to the region of reverse command. It begins at Minimum Power Required for propeller planes, not at Best Glide (no wind) aka L/Dmax. For jets, it begins at L/Dmax which is best glide which is minimum thrust which for jets only is Max E. For both, I view a different sense of Reverse Command in which you use pitch for speed control but change which way you pitch and this point is L/Dmax aka best glide (still air) aka min drag. See Medium searching for “Back Side of the Power Curve vs Drag Curve.” Propeller airplanes minimum power required aka max endurance is the division between normal and reverse demand. You need more power to fly slower than Max E and more power to fly faster than Max E. This Max E point differs propellers versus jets. Note Vref is slower than Vg though typically faster than propeller Vx and faster than propeller Max E. Lastly, the stall speed on the charts is not to proportion as it appears near zero (I’ll guess it is closer to forty or fifty).
@FalconImagery , great video and explanation. Does the Vg then correspond to the Vmd? Can you make a video explaining this in the context of Vmd-VmP (minimum power) and maximum range vs maximum endurance please?
Vmd is the minimum drag speed, where the parasitic and induced drag curves intersect, basically Vg (Best Glide Speed), or also the speed Vbe which gives you the maximum endurance speed.
Try Medium “Back Side of the Power Curve vs Drag Curve.” Note that so long as you are not near your ceiling, and not so high compressibility changes the values, Max E has a specific AOA while Max R in no wind also has a specific AOA. See the glider handbooks regarding best glide in wind and you can apply this to Max R in wind noting Max R with tailwind has a limit of no slower than Max E. Why you’d bother with such, I don’t know. It is the headwind that matters. Why does near the ceiling matter? Because now thrust available and power available come into play as you no longer have excess. Note as Vx and Vy collapse to a point at ceiling, so too do Max E and Max R as at ceiling, you only have one flyable speed one flyable AOA. For Max R on the jet, do the tangent from origin trick on the Drag curve (as you did on the power curve for propeller; yes tangent on power curve lines up with bottom of drag curve).
Very well explained. Great video!
Excellent video!
I prefer to call it the region of Reverse Demand as opposed to the region of reverse command. It begins at Minimum Power Required for propeller planes, not at Best Glide (no wind) aka L/Dmax. For jets, it begins at L/Dmax which is best glide which is minimum thrust which for jets only is Max E. For both, I view a different sense of Reverse Command in which you use pitch for speed control but change which way you pitch and this point is L/Dmax aka best glide (still air) aka min drag. See Medium searching for “Back Side of the Power Curve vs Drag Curve.” Propeller airplanes minimum power required aka max endurance is the division between normal and reverse demand. You need more power to fly slower than Max E and more power to fly faster than Max E. This Max E point differs propellers versus jets. Note Vref is slower than Vg though typically faster than propeller Vx and faster than propeller Max E. Lastly, the stall speed on the charts is not to proportion as it appears near zero (I’ll guess it is closer to forty or fifty).
Great explanation thanks
You're welcome!
@FalconImagery , great video and explanation. Does the Vg then correspond to the Vmd? Can you make a video explaining this in the context of Vmd-VmP (minimum power) and maximum range vs maximum endurance please?
Vmd is the minimum drag speed, where the parasitic and induced drag curves intersect, basically Vg (Best Glide Speed), or also the speed Vbe which gives you the maximum endurance speed.
Try Medium “Back Side of the Power Curve vs Drag Curve.” Note that so long as you are not near your ceiling, and not so high compressibility changes the values, Max E has a specific AOA while Max R in no wind also has a specific AOA. See the glider handbooks regarding best glide in wind and you can apply this to Max R in wind noting Max R with tailwind has a limit of no slower than Max E. Why you’d bother with such, I don’t know. It is the headwind that matters. Why does near the ceiling matter? Because now thrust available and power available come into play as you no longer have excess. Note as Vx and Vy collapse to a point at ceiling, so too do Max E and Max R as at ceiling, you only have one flyable speed one flyable AOA. For Max R on the jet, do the tangent from origin trick on the Drag curve (as you did on the power curve for propeller; yes tangent on power curve lines up with bottom of drag curve).
Great video
tnx