Linked Questions

14 votes
5 answers
6k views

Where is the 'zone of reversed commands...'?

There seems to be some confusion about where the 'zone of reversed commands' really is, i.e. where a decrease of airspeed results in an increase of drag. Some references place that zone to the left ...
xxavier's user avatar
  • 11.1k
15 votes
4 answers
15k views

What is the propeller efficiency, $μ_p$, of modern propellers for light sport aircraft?

Roskam's book on preliminary design gives a value of 0.7 for "homebuilt" aircraft and 0.8 for general aviation. What explains this difference in propeller efficiency? The content of Roskam's book is ...
user26358's user avatar
  • 469
12 votes
2 answers
4k views

Under what conditions can the maximum angle of climb be achieved for jet and propeller aircraft?

I know that the maximum angle of climb is reached at maximum specific excess thrust (S.E.T.) for jet airplanes, or minimum drag or maximum $\frac{L}{D}$. Is this true, and if yes, is this valid also ...
mezzanaccio's user avatar
  • 1,739
6 votes
2 answers
3k views

How does climb-rate vary with density/pressure altitude?

I'm seeking to write a little web or phone app which can help me choose the best cruising altitude based upon winds aloft. I know Garmin Pilot (and probably Foreflight) have a cruising altitude ...
Jemenake's user avatar
  • 309
10 votes
2 answers
1k views

In a jet, are Vy and Vx achieved at a constant AOA at all altitudes?

In terms of IAS, Vx (best climb angle speed) increases with altitude, and Vy (best climb rate speed) decreases with altitude, until they meet at the plane's absolute ceiling. http://cospilot.com/...
Musmus Klapa's user avatar
3 votes
1 answer
897 views

Why isn't Vy lower than the speeds for best L/D ratio and best glide ratio in an airplane with a piston engine and a variable-speed prop?

This answer to a related question implies that if the power available were constant regardless of airspeed, Vy would occur at approximately the angle-of-attack that yields the minimum sink rate with ...
quiet flyer's user avatar
  • 22.7k
-1 votes
4 answers
508 views

How is Vx speed and Vy affected when climbing?

If my speed for best angle of climb is 60 and rate is 79, if I kept a 500 fpm climb to my cruise altitude of let’s say 4500, would those speed change? The flights are being done on separate occasions.
youngpilot's user avatar
0 votes
1 answer
458 views

Is it better to increase speed in a climb? [duplicate]

In straight and level flight, lift is determined by speed and angle of attack. If we are heavier, we must go faster to generate more lift, at the same angle of attack. At the same speed, angle of ...
Robert DiGiovanni's user avatar
3 votes
1 answer
356 views

Is V best endurance configuration the best way to save a heavily overloaded aircraft?

After reading this, we all agree "the experienced pilot takes over, lowers the nose, and the plane is saved". Not bad advice, but what speed offers the greatest amount of excess thrust ...
Robert DiGiovanni's user avatar
1 vote
2 answers
256 views

Density Altitude and Cruise Performance

Obviously higher temperature than standard and lower pressure than standard (high density altitude) hurt takeoff performance. The wings have less air molecules to produce lift with, and a typical ...
Terry's user avatar
  • 335