uwochris
Flightinfo's sexiest user
- Joined
- Dec 21, 2001
- Posts
- 381
Hey guys,
I got a couple of questions regarding airspeeds.
(1) Why does Vy decrease with altitude while Vx increases with altitude?
(2) What are some common factors that affect Vy and Vx? The only ones I am aware of are weight, density altitudes, altitude, and wind (only a factor for Vx). Are there other common factors that I should keep in mind?
(3) Why does Vy decrease with increased weight? Is it because lower weights imply less induced drag, so higher climb rates can be obtained?
(4) When I read about how higher density altitudes and higher weights reduce the angle of climb and the rate of climb, does that mean I should be using a different airspeed? ie) by reduced rate/angle of climb, do my manuals imply that the actual rate and angle are reduced for any given airspeeds, or do they imply the actual airspeeds are reduced? For example, should I use the IAS indicated in my POH, and just accept the reduced performance, or should I try to make an adjustment?
(5) Is there an error in IAS with higher altitudes? That is, since the air at higher altitudes is less dense, isn't there less "ram" air pressure entering the pitot, and hence, IAS will be reduced for any given TAS? I know I read somewhere that the airplane will stall at the same IAS for all altitudes, however, the TAS will be higher above. Essentially, I am asking whether or not IAS decreases consistently with altitude, even if the actual airpseed of the airplane may remain the same.
(6) Why does Range increase with altitude, while Endurance decreases with altitude?
(7) Is there a difference between Best Glide and Best Range speed; or, are both of them the best "lift to drag" ratio?
I hope I didn't ask too many questions
Thanks in advance guys.
Chris.
I got a couple of questions regarding airspeeds.
(1) Why does Vy decrease with altitude while Vx increases with altitude?
(2) What are some common factors that affect Vy and Vx? The only ones I am aware of are weight, density altitudes, altitude, and wind (only a factor for Vx). Are there other common factors that I should keep in mind?
(3) Why does Vy decrease with increased weight? Is it because lower weights imply less induced drag, so higher climb rates can be obtained?
(4) When I read about how higher density altitudes and higher weights reduce the angle of climb and the rate of climb, does that mean I should be using a different airspeed? ie) by reduced rate/angle of climb, do my manuals imply that the actual rate and angle are reduced for any given airspeeds, or do they imply the actual airspeeds are reduced? For example, should I use the IAS indicated in my POH, and just accept the reduced performance, or should I try to make an adjustment?
(5) Is there an error in IAS with higher altitudes? That is, since the air at higher altitudes is less dense, isn't there less "ram" air pressure entering the pitot, and hence, IAS will be reduced for any given TAS? I know I read somewhere that the airplane will stall at the same IAS for all altitudes, however, the TAS will be higher above. Essentially, I am asking whether or not IAS decreases consistently with altitude, even if the actual airpseed of the airplane may remain the same.
(6) Why does Range increase with altitude, while Endurance decreases with altitude?
(7) Is there a difference between Best Glide and Best Range speed; or, are both of them the best "lift to drag" ratio?
I hope I didn't ask too many questions
Thanks in advance guys.
Chris.
